Framebuffer子系统
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本文转载自:http://blog.csdn.net/av_geek/article/details/40897115
本文将介绍Framebuffer子系统
目标平台:TQ2440 CPU:s3c2440
LCD设备:3.5英寸,分辨率320X240
1. 概述
Framebuffer,中文名字是帧缓冲,这个帧也就是一副图像所需要的数据。因此,帧缓冲其实就是LCD设备的驱动程序。Linux中,framebuffer子系统框架如下:
核心层的代码以fbmem.c为主,核心层包括许多与具体硬件无关的代码,并且提供了API给用户空间。用户空间使用系统调用,系统调用会使用相应的API函数,最后会调用驱动层实现功能。对于不同的设备,驱动层的代码将有所不同。
接下来的内容中,首先给出framerbuffer使用的数据结构;随后简单描述framerbuffer核心层;最后,针对S3C2440,对驱动代码进行分析。
2. 数据结构
2.1 fb_info 结构
该结构是内核用于描述一个特定framebuffer设备。其中包含了几个重要的结构,将在下面介绍。
下列代码位于include/linux/fb.h
- struct fb_info {
- int node;
- int flags;
- struct mutex lock; /* Lock for open/release/ioctl funcs */
- struct fb_var_screeninfo var; /* Current var */
- struct fb_fix_screeninfo fix; /* Current fix */
- struct fb_monspecs monspecs; /* Current Monitor specs */
- struct work_struct queue; /* Framebuffer event queue */
- struct fb_pixmap pixmap; /* Image hardware mapper */
- struct fb_pixmap sprite; /* Cursor hardware mapper */
- struct fb_cmap cmap; /* Current cmap */
- struct list_head modelist; /* mode list */
- struct fb_videomode *mode; /* current mode */
- #ifdef CONFIG_FB_BACKLIGHT
- /* assigned backlight device */
- /* set before framebuffer registration,
- remove after unregister */
- struct backlight_device *bl_dev;
- /* Backlight level curve */
- struct mutex bl_curve_mutex;
- u8 bl_curve[FB_BACKLIGHT_LEVELS];
- #endif
- #ifdef CONFIG_FB_DEFERRED_IO
- struct delayed_work deferred_work;
- struct fb_deferred_io *fbdefio;
- #endif
- struct fb_ops *fbops;
- struct device *device; /* This is the parent */
- struct device *dev; /* This is this fb device */
- int class_flag; /* private sysfs flags */
- #ifdef CONFIG_FB_TILEBLITTING
- struct fb_tile_ops *tileops; /* Tile Blitting */
- #endif
- char __iomem *screen_base; /* Virtual address */
- unsigned long screen_size; /* Amount of ioremapped VRAM or 0 */
- void *pseudo_palette; /* Fake palette of 16 colors */
- #define FBINFO_STATE_RUNNING 0
- #define FBINFO_STATE_SUSPENDED 1
- u32 state; /* Hardware state i.e suspend */
- void *fbcon_par; /* fbcon use-only private area */
- /* From here on everything is device dependent */
- void *par;
- };
- struct fb_info {
- int node;
- int flags;
- struct mutex lock; /* Lock for open/release/ioctl funcs */
- struct fb_var_screeninfo var; /* Current var */
- struct fb_fix_screeninfo fix; /* Current fix */
- struct fb_monspecs monspecs; /* Current Monitor specs */
- struct work_struct queue; /* Framebuffer event queue */
- struct fb_pixmap pixmap; /* Image hardware mapper */
- struct fb_pixmap sprite; /* Cursor hardware mapper */
- struct fb_cmap cmap; /* Current cmap */
- struct list_head modelist; /* mode list */
- struct fb_videomode *mode; /* current mode */
- #ifdef CONFIG_FB_BACKLIGHT
- /* assigned backlight device */
- /* set before framebuffer registration,
- remove after unregister */
- struct backlight_device *bl_dev;
- /* Backlight level curve */
- struct mutex bl_curve_mutex;
- u8 bl_curve[FB_BACKLIGHT_LEVELS];
- #endif
- #ifdef CONFIG_FB_DEFERRED_IO
- struct delayed_work deferred_work;
- struct fb_deferred_io *fbdefio;
- #endif
- struct fb_ops *fbops;
- struct device *device; /* This is the parent */
- struct device *dev; /* This is this fb device */
- int class_flag; /* private sysfs flags */
- #ifdef CONFIG_FB_TILEBLITTING
- struct fb_tile_ops *tileops; /* Tile Blitting */
- #endif
- char __iomem *screen_base; /* Virtual address */
- unsigned long screen_size; /* Amount of ioremapped VRAM or 0 */
- void *pseudo_palette; /* Fake palette of 16 colors */
- #define FBINFO_STATE_RUNNING 0
- #define FBINFO_STATE_SUSPENDED 1
- u32 state; /* Hardware state i.e suspend */
- void *fbcon_par; /* fbcon use-only private area */
- /* From here on everything is device dependent */
- void *par;
- };
2.2 fb_fix_screeninfo结构
该数据结构是不可改变的,也就是说用户空间不能改变该结构中的任何成员,在核心层我们将会看到这点。
下列代码位于include/linux/fb.h
- struct fb_fix_screeninfo {
- char id[16]; /* identification string eg "TT Builtin" */
- unsigned long smem_start; /* Start of frame buffer mem */
- /* (physical address) */
- __u32 smem_len; /* Length of frame buffer mem */
- __u32 type; /* see FB_TYPE_* */
- __u32 type_aux; /* Interleave for interleaved Planes */
- __u32 visual; /* see FB_VISUAL_* */
- __u16 xpanstep; /* zero if no hardware panning */
- __u16 ypanstep; /* zero if no hardware panning */
- __u16 ywrapstep; /* zero if no hardware ywrap */
- __u32 line_length; /* length of a line in bytes */
- unsigned long mmio_start; /* Start of Memory Mapped I/O */
- /* (physical address) */
- __u32 mmio_len; /* Length of Memory Mapped I/O */
- __u32 accel; /* Indicate to driver which */
- /* specific chip/card we have */
- __u16 reserved[3]; /* Reserved for future compatibility */
- };
- struct fb_fix_screeninfo {
- char id[16]; /* identification string eg "TT Builtin" */
- unsigned long smem_start; /* Start of frame buffer mem */
- /* (physical address) */
- __u32 smem_len; /* Length of frame buffer mem */
- __u32 type; /* see FB_TYPE_* */
- __u32 type_aux; /* Interleave for interleaved Planes */
- __u32 visual; /* see FB_VISUAL_* */
- __u16 xpanstep; /* zero if no hardware panning */
- __u16 ypanstep; /* zero if no hardware panning */
- __u16 ywrapstep; /* zero if no hardware ywrap */
- __u32 line_length; /* length of a line in bytes */
- unsigned long mmio_start; /* Start of Memory Mapped I/O */
- /* (physical address) */
- __u32 mmio_len; /* Length of Memory Mapped I/O */
- __u32 accel; /* Indicate to driver which */
- /* specific chip/card we have */
- __u16 reserved[3]; /* Reserved for future compatibility */
- };
2.3 fb_var_screeninfo结构
该数据结构是可以改变的,也就是说用户空间可以改变该结构中的成员。该数据结构中的很多成员就由板级信息复制而来,在驱动代码中我们将会看到这点。
下列代码位于include/linux/fb.h
- struct fb_var_screeninfo {
- __u32 xres; /* visible resolution */
- __u32 yres;
- __u32 xres_virtual; /* virtual resolution */
- __u32 yres_virtual;
- __u32 xoffset; /* offset from virtual to visible */
- __u32 yoffset; /* resolution */
- __u32 bits_per_pixel; /* guess what */
- __u32 grayscale; /* != 0 Graylevels instead of colors */
- struct fb_bitfield red; /* bitfield in fb mem if true color, */
- struct fb_bitfield green; /* else only length is significant */
- struct fb_bitfield blue;
- struct fb_bitfield transp; /* transparency */
- __u32 nonstd; /* != 0 Non standard pixel format */
- __u32 activate; /* see FB_ACTIVATE_* */
- __u32 height; /* height of picture in mm */
- __u32 width; /* width of picture in mm */
- __u32 accel_flags; /* (OBSOLETE) see fb_info.flags */
- /* Timing: All values in pixclocks, except pixclock (of course) */
- __u32 pixclock; /* pixel clock in ps (pico seconds) */
- __u32 left_margin; /* time from sync to picture */
- __u32 right_margin; /* time from picture to sync */
- __u32 upper_margin; /* time from sync to picture */
- __u32 lower_margin;
- __u32 hsync_len; /* length of horizontal sync */
- __u32 vsync_len; /* length of vertical sync */
- __u32 sync; /* see FB_SYNC_* */
- __u32 vmode; /* see FB_VMODE_* */
- __u32 rotate; /* angle we rotate counter clockwise */
- __u32 reserved[5]; /* Reserved for future compatibility */
- };
- struct fb_var_screeninfo {
- __u32 xres; /* visible resolution */
- __u32 yres;
- __u32 xres_virtual; /* virtual resolution */
- __u32 yres_virtual;
- __u32 xoffset; /* offset from virtual to visible */
- __u32 yoffset; /* resolution */
- __u32 bits_per_pixel; /* guess what */
- __u32 grayscale; /* != 0 Graylevels instead of colors */
- struct fb_bitfield red; /* bitfield in fb mem if true color, */
- struct fb_bitfield green; /* else only length is significant */
- struct fb_bitfield blue;
- struct fb_bitfield transp; /* transparency */
- __u32 nonstd; /* != 0 Non standard pixel format */
- __u32 activate; /* see FB_ACTIVATE_* */
- __u32 height; /* height of picture in mm */
- __u32 width; /* width of picture in mm */
- __u32 accel_flags; /* (OBSOLETE) see fb_info.flags */
- /* Timing: All values in pixclocks, except pixclock (of course) */
- __u32 pixclock; /* pixel clock in ps (pico seconds) */
- __u32 left_margin; /* time from sync to picture */
- __u32 right_margin; /* time from picture to sync */
- __u32 upper_margin; /* time from sync to picture */
- __u32 lower_margin;
- __u32 hsync_len; /* length of horizontal sync */
- __u32 vsync_len; /* length of vertical sync */
- __u32 sync; /* see FB_SYNC_* */
- __u32 vmode; /* see FB_VMODE_* */
- __u32 rotate; /* angle we rotate counter clockwise */
- __u32 reserved[5]; /* Reserved for future compatibility */
- };
2.4 fb_ops结构
该结构描述了用于fb_info的方法,这些方法中有些是要驱动程序提供的,而有些可以使用内核提供的方法。
下列代码位于include/linux/fb.h
- /*
- * Frame buffer operations
- *
- * LOCKING NOTE: those functions must _ALL_ be called with the console
- * semaphore held, this is the only suitable locking mechanism we have
- * in 2.6. Some may be called at interrupt time at this point though.
- */
- struct fb_ops {
- /* open/release and usage marking */
- struct module *owner;
- int (*fb_open)(struct fb_info *info, int user);
- int (*fb_release)(struct fb_info *info, int user);
- /* For framebuffers with strange non linear layouts or that do not
- * work with normal memory mapped access
- */
- ssize_t (*fb_read)(struct fb_info *info, char __user *buf,
- size_t count, loff_t *ppos);
- ssize_t (*fb_write)(struct fb_info *info, const char __user *buf,
- size_t count, loff_t *ppos);
- /* checks var and eventually tweaks it to something supported,
- * DO NOT MODIFY PAR */
- int (*fb_check_var)(struct fb_var_screeninfo *var, struct fb_info *info);
- /* set the video mode according to info->var */
- int (*fb_set_par)(struct fb_info *info);
- /* set color register */
- int (*fb_setcolreg)(unsigned regno, unsigned red, unsigned green,
- unsigned blue, unsigned transp, struct fb_info *info);
- /* set color registers in batch */
- int (*fb_setcmap)(struct fb_cmap *cmap, struct fb_info *info);
- /* blank display */
- int (*fb_blank)(int blank, struct fb_info *info);
- /* pan display */
- int (*fb_pan_display)(struct fb_var_screeninfo *var, struct fb_info *info);
- /* Draws a rectangle */
- void (*fb_fillrect) (struct fb_info *info, const struct fb_fillrect *rect);
- /* Copy data from area to another */
- void (*fb_copyarea) (struct fb_info *info, const struct fb_copyarea *region);
- /* Draws a image to the display */
- void (*fb_imageblit) (struct fb_info *info, const struct fb_image *image);
- /* Draws cursor */
- int (*fb_cursor) (struct fb_info *info, struct fb_cursor *cursor);
- /* Rotates the display */
- void (*fb_rotate)(struct fb_info *info, int angle);
- /* wait for blit idle, optional */
- int (*fb_sync)(struct fb_info *info);
- /* perform fb specific ioctl (optional) */
- int (*fb_ioctl)(struct fb_info *info, unsigned int cmd,
- unsigned long arg);
- /* Handle 32bit compat ioctl (optional) */
- int (*fb_compat_ioctl)(struct fb_info *info, unsigned cmd,
- unsigned long arg);
- /* perform fb specific mmap */
- int (*fb_mmap)(struct fb_info *info, struct vm_area_struct *vma);
- /* save current hardware state */
- void (*fb_save_state)(struct fb_info *info);
- /* restore saved state */
- void (*fb_restore_state)(struct fb_info *info);
- /* get capability given var */
- void (*fb_get_caps)(struct fb_info *info, struct fb_blit_caps *caps,
- struct fb_var_screeninfo *var);
- };
- /*
- * Frame buffer operations
- *
- * LOCKING NOTE: those functions must _ALL_ be called with the console
- * semaphore held, this is the only suitable locking mechanism we have
- * in 2.6. Some may be called at interrupt time at this point though.
- */
- struct fb_ops {
- /* open/release and usage marking */
- struct module *owner;
- int (*fb_open)(struct fb_info *info, int user);
- int (*fb_release)(struct fb_info *info, int user);
- /* For framebuffers with strange non linear layouts or that do not
- * work with normal memory mapped access
- */
- ssize_t (*fb_read)(struct fb_info *info, char __user *buf,
- size_t count, loff_t *ppos);
- ssize_t (*fb_write)(struct fb_info *info, const char __user *buf,
- size_t count, loff_t *ppos);
- /* checks var and eventually tweaks it to something supported,
- * DO NOT MODIFY PAR */
- int (*fb_check_var)(struct fb_var_screeninfo *var, struct fb_info *info);
- /* set the video mode according to info->var */
- int (*fb_set_par)(struct fb_info *info);
- /* set color register */
- int (*fb_setcolreg)(unsigned regno, unsigned red, unsigned green,
- unsigned blue, unsigned transp, struct fb_info *info);
- /* set color registers in batch */
- int (*fb_setcmap)(struct fb_cmap *cmap, struct fb_info *info);
- /* blank display */
- int (*fb_blank)(int blank, struct fb_info *info);
- /* pan display */
- int (*fb_pan_display)(struct fb_var_screeninfo *var, struct fb_info *info);
- /* Draws a rectangle */
- void (*fb_fillrect) (struct fb_info *info, const struct fb_fillrect *rect);
- /* Copy data from area to another */
- void (*fb_copyarea) (struct fb_info *info, const struct fb_copyarea *region);
- /* Draws a image to the display */
- void (*fb_imageblit) (struct fb_info *info, const struct fb_image *image);
- /* Draws cursor */
- int (*fb_cursor) (struct fb_info *info, struct fb_cursor *cursor);
- /* Rotates the display */
- void (*fb_rotate)(struct fb_info *info, int angle);
- /* wait for blit idle, optional */
- int (*fb_sync)(struct fb_info *info);
- /* perform fb specific ioctl (optional) */
- int (*fb_ioctl)(struct fb_info *info, unsigned int cmd,
- unsigned long arg);
- /* Handle 32bit compat ioctl (optional) */
- int (*fb_compat_ioctl)(struct fb_info *info, unsigned cmd,
- unsigned long arg);
- /* perform fb specific mmap */
- int (*fb_mmap)(struct fb_info *info, struct vm_area_struct *vma);
- /* save current hardware state */
- void (*fb_save_state)(struct fb_info *info);
- /* restore saved state */
- void (*fb_restore_state)(struct fb_info *info);
- /* get capability given var */
- void (*fb_get_caps)(struct fb_info *info, struct fb_blit_caps *caps,
- struct fb_var_screeninfo *var);
- };
3. frambuffer核心层
首先来看下frmaebuffer子系统的初始化函数。
3.1 fbmem_init和fbmem_exit
下列代码位于drivers/video/fbmem.c
- /**
- * fbmem_init - init frame buffer subsystem
- *
- * Initialize the frame buffer subsystem.
- *
- * NOTE: This function is _only_ to be called by drivers/char/mem.c.
- *
- */
- static int __init
- fbmem_init(void)
- {
- proc_create("fb", 0, NULL, &fb_proc_fops);
- if (register_chrdev(FB_MAJOR,"fb",&fb_fops)) /*注册字符设备,major=29*/
- printk("unable to get major %d for fb devs\n", FB_MAJOR);
- fb_class = class_create(THIS_MODULE, "graphics"); /*创建类*/
- if (IS_ERR(fb_class)) {
- printk(KERN_WARNING "Unable to create fb class; errno = %ld\n", PTR_ERR(fb_class));
- fb_class = NULL;
- }
- return 0;
- }
- #ifdef MODULE
- module_init(fbmem_init);
- static void __exit
- fbmem_exit(void)
- {
- remove_proc_entry("fb", NULL);
- class_destroy(fb_class);
- unregister_chrdev(FB_MAJOR, "fb");
- }
- module_exit(fbmem_exit);
- MODULE_LICENSE("GPL");
- MODULE_DESCRIPTION("Framebuffer base");
- #else
- subsys_initcall(fbmem_init);
- #endif
- static const struct file_operations fb_fops = {
- .owner = THIS_MODULE,
- .read = fb_read,
- .write = fb_write,
- .unlocked_ioctl = fb_ioctl,
- #ifdef CONFIG_COMPAT
- .compat_ioctl = fb_compat_ioctl,
- #endif
- .mmap = fb_mmap,
- .open = fb_open,
- .release = fb_release,
- #ifdef HAVE_ARCH_FB_UNMAPPED_AREA
- .get_unmapped_area = get_fb_unmapped_area,
- #endif
- #ifdef CONFIG_FB_DEFERRED_IO
- .fsync = fb_deferred_io_fsync,
- #endif
- };
- /**
- * fbmem_init - init frame buffer subsystem
- *
- * Initialize the frame buffer subsystem.
- *
- * NOTE: This function is _only_ to be called by drivers/char/mem.c.
- *
- */
- static int __init
- fbmem_init(void)
- {
- proc_create("fb", 0, NULL, &fb_proc_fops);
- if (register_chrdev(FB_MAJOR,"fb",&fb_fops)) /*注册字符设备,major=29*/
- printk("unable to get major %d for fb devs\n", FB_MAJOR);
- fb_class = class_create(THIS_MODULE, "graphics"); /*创建类*/
- if (IS_ERR(fb_class)) {
- printk(KERN_WARNING "Unable to create fb class; errno = %ld\n", PTR_ERR(fb_class));
- fb_class = NULL;
- }
- return 0;
- }
- #ifdef MODULE
- module_init(fbmem_init);
- static void __exit
- fbmem_exit(void)
- {
- remove_proc_entry("fb", NULL);
- class_destroy(fb_class);
- unregister_chrdev(FB_MAJOR, "fb");
- }
- module_exit(fbmem_exit);
- MODULE_LICENSE("GPL");
- MODULE_DESCRIPTION("Framebuffer base");
- #else
- subsys_initcall(fbmem_init);
- #endif
- static const struct file_operations fb_fops = {
- .owner = THIS_MODULE,
- .read = fb_read,
- .write = fb_write,
- .unlocked_ioctl = fb_ioctl,
- #ifdef CONFIG_COMPAT
- .compat_ioctl = fb_compat_ioctl,
- #endif
- .mmap = fb_mmap,
- .open = fb_open,
- .release = fb_release,
- #ifdef HAVE_ARCH_FB_UNMAPPED_AREA
- .get_unmapped_area = get_fb_unmapped_area,
- #endif
- #ifdef CONFIG_FB_DEFERRED_IO
- .fsync = fb_deferred_io_fsync,
- #endif
- };
我们看到,如果不是作为模块,那么该初始化程序将在subsys_initcall阶段被调用。初始化时,仅仅注册了一个字符设备,并创建了一个类。通过字符设备,提供了API给用户空间,包open,release,write,read等。
随后我们看看如何分配一个fb_info结构。
3.2 framebuffer_alloc
下列代码位于drivers/video/fbmem.c
- /**
- * framebuffer_alloc - creates a new frame buffer info structure
- *
- * @size: size of driver private data, can be zero
- * @dev: pointer to the device for this fb, this can be NULL
- *
- * Creates a new frame buffer info structure. Also reserves @size bytes
- * for driver private data (info->par). info->par (if any) will be
- * aligned to sizeof(long).
- *
- * Returns the new structure, or NULL if an error occured.
- *
- */
- struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
- {
- #define BYTES_PER_LONG (BITS_PER_LONG/8)
- #define PADDING (BYTES_PER_LONG - (sizeof(struct fb_info) % BYTES_PER_LONG))
- int fb_info_size = sizeof(struct fb_info);
- struct fb_info *info;
- char *p;
- if (size)
- fb_info_size += PADDING;
- p = kzalloc(fb_info_size + size, GFP_KERNEL);
- if (!p)
- return NULL;
- info = (struct fb_info *) p;
- if (size)
- info->par = p + fb_info_size;
- info->device = dev;
- #ifdef CONFIG_FB_BACKLIGHT
- mutex_init(&info->bl_curve_mutex);
- #endif
- return info;
- #undef PADDING
- #undef BYTES_PER_LONG
- }
- EXPORT_SYMBOL(framebuffer_alloc);
- /**
- * framebuffer_alloc - creates a new frame buffer info structure
- *
- * @size: size of driver private data, can be zero
- * @dev: pointer to the device for this fb, this can be NULL
- *
- * Creates a new frame buffer info structure. Also reserves @size bytes
- * for driver private data (info->par). info->par (if any) will be
- * aligned to sizeof(long).
- *
- * Returns the new structure, or NULL if an error occured.
- *
- */
- struct fb_info *framebuffer_alloc(size_t size, struct device *dev)
- {
- #define BYTES_PER_LONG (BITS_PER_LONG/8)
- #define PADDING (BYTES_PER_LONG - (sizeof(struct fb_info) % BYTES_PER_LONG))
- int fb_info_size = sizeof(struct fb_info);
- struct fb_info *info;
- char *p;
- if (size)
- fb_info_size += PADDING;
- p = kzalloc(fb_info_size + size, GFP_KERNEL);
- if (!p)
- return NULL;
- info = (struct fb_info *) p;
- if (size)
- info->par = p + fb_info_size;
- info->device = dev;
- #ifdef CONFIG_FB_BACKLIGHT
- mutex_init(&info->bl_curve_mutex);
- #endif
- return info;
- #undef PADDING
- #undef BYTES_PER_LONG
- }
- EXPORT_SYMBOL(framebuffer_alloc);
在进行分配时,根据参数size的大小,分配了b_info_size + size的空间,然后让fb_info->par指向size的空间。因此par所指向的空间可视为设备特有的数据。
在分配了fb_info结构之后,需要将它注册到内核中。注册由register_framebuffer完成。我们来看下。
3.3 register_framebuffer
下列代码位于drivers/video/fbmem.c
- /**
- * register_framebuffer - registers a frame buffer device
- * @fb_info: frame buffer info structure
- *
- * Registers a frame buffer device @fb_info.
- *
- * Returns negative errno on error, or zero for success.
- *
- */
- int
- register_framebuffer(struct fb_info *fb_info)
- {
- int i;
- struct fb_event event;
- struct fb_videomode mode;
- if (num_registered_fb == FB_MAX) /*最多32个FB*/
- return -ENXIO;
- if (fb_check_foreignness(fb_info))
- return -ENOSYS;
- num_registered_fb++; /*对注册的FB计数*/
- /*寻找第一个空位*/
- for (i = 0 ; i < FB_MAX; i++)/*FB_MAX=32,也就是最多32个framebuffer*/
- if (!registered_fb[i]) /*struct fb_info *registered_fb[FB_MAX]*/
- break;
- fb_info->node = i;
- mutex_init(&fb_info->lock); /*初始化互斥体*/
- fb_info->dev = device_create(fb_class, fb_info->device,/*创建设备节点,节点名为fbx*/
- MKDEV(FB_MAJOR, i), NULL, "fb%d", i);
- if (IS_ERR(fb_info->dev)) {
- /* Not fatal */
- printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ld\n", i, PTR_ERR(fb_info->dev));
- fb_info->dev = NULL;
- } else
- fb_init_device(fb_info); /*初始化,在class/graphics/fbx/下创建设备属性*/
- if (fb_info->pixmap.addr == NULL) {
- fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);/*分配内存,1024 * 8字节*/
- if (fb_info->pixmap.addr) {
- fb_info->pixmap.size = FBPIXMAPSIZE;
- fb_info->pixmap.buf_align = 1;
- fb_info->pixmap.scan_align = 1;
- fb_info->pixmap.access_align = 32;
- fb_info->pixmap.flags = FB_PIXMAP_DEFAULT;
- }
- }
- fb_info->pixmap.offset = 0;
- if (!fb_info->pixmap.blit_x)
- fb_info->pixmap.blit_x = ~(u32)0;
- if (!fb_info->pixmap.blit_y)
- fb_info->pixmap.blit_y = ~(u32)0;
- if (!fb_info->modelist.prev || !fb_info->modelist.next) /*该链表没有指向其他节点*/
- INIT_LIST_HEAD(&fb_info->modelist); /*初始化链表头*/
- fb_var_to_videomode(&mode, &fb_info->var);/*转换fb_var_screeninfo成fb_videomode*/
- fb_add_videomode(&mode, &fb_info->modelist);/*添加mode至链表中*/
- registered_fb[i] = fb_info;
- event.info = fb_info;
- if (!lock_fb_info(fb_info))
- return -ENODEV;
- fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);/*???*/
- unlock_fb_info(fb_info);
- return 0;
- }
- /**
- * register_framebuffer - registers a frame buffer device
- * @fb_info: frame buffer info structure
- *
- * Registers a frame buffer device @fb_info.
- *
- * Returns negative errno on error, or zero for success.
- *
- */
- int
- register_framebuffer(struct fb_info *fb_info)
- {
- int i;
- struct fb_event event;
- struct fb_videomode mode;
- if (num_registered_fb == FB_MAX) /*最多32个FB*/
- return -ENXIO;
- if (fb_check_foreignness(fb_info))
- return -ENOSYS;
- num_registered_fb++; /*对注册的FB计数*/
- /*寻找第一个空位*/
- for (i = 0 ; i < FB_MAX; i++)/*FB_MAX=32,也就是最多32个framebuffer*/
- if (!registered_fb[i]) /*struct fb_info *registered_fb[FB_MAX]*/
- break;
- fb_info->node = i;
- mutex_init(&fb_info->lock); /*初始化互斥体*/
- fb_info->dev = device_create(fb_class, fb_info->device,/*创建设备节点,节点名为fbx*/
- MKDEV(FB_MAJOR, i), NULL, "fb%d", i);
- if (IS_ERR(fb_info->dev)) {
- /* Not fatal */
- printk(KERN_WARNING "Unable to create device for framebuffer %d; errno = %ld\n", i, PTR_ERR(fb_info->dev));
- fb_info->dev = NULL;
- } else
- fb_init_device(fb_info); /*初始化,在class/graphics/fbx/下创建设备属性*/
- if (fb_info->pixmap.addr == NULL) {
- fb_info->pixmap.addr = kmalloc(FBPIXMAPSIZE, GFP_KERNEL);/*分配内存,1024 * 8字节*/
- if (fb_info->pixmap.addr) {
- fb_info->pixmap.size = FBPIXMAPSIZE;
- fb_info->pixmap.buf_align = 1;
- fb_info->pixmap.scan_align = 1;
- fb_info->pixmap.access_align = 32;
- fb_info->pixmap.flags = FB_PIXMAP_DEFAULT;
- }
- }
- fb_info->pixmap.offset = 0;
- if (!fb_info->pixmap.blit_x)
- fb_info->pixmap.blit_x = ~(u32)0;
- if (!fb_info->pixmap.blit_y)
- fb_info->pixmap.blit_y = ~(u32)0;
- if (!fb_info->modelist.prev || !fb_info->modelist.next) /*该链表没有指向其他节点*/
- INIT_LIST_HEAD(&fb_info->modelist); /*初始化链表头*/
- fb_var_to_videomode(&mode, &fb_info->var);/*转换fb_var_screeninfo成fb_videomode*/
- fb_add_videomode(&mode, &fb_info->modelist);/*添加mode至链表中*/
- registered_fb[i] = fb_info;
- event.info = fb_info;
- if (!lock_fb_info(fb_info))
- return -ENODEV;
- fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);/*???*/
- unlock_fb_info(fb_info);
- return 0;
- }
从这个函数我们可以看出,framebuffer子系统只支持32个设备。在创建了设备节点以后,建立设备属性节点,随后将fb_var_screeninfo转换成fb_videomode,最后添加fb_videomode至链表中。
我们看下其中调用的函数,首先是fb_init_device。
下列代码位于drivers/video/fbsysfs.c
- int fb_init_device(struct fb_info *fb_info)
- {
- int i, error = 0;
- dev_set_drvdata(fb_info->dev, fb_info);
- fb_info->class_flag |= FB_SYSFS_FLAG_ATTR;
- /*建立设备属性*/
- for (i = 0; i < ARRAY_SIZE(device_attrs); i++) {
- error = device_create_file(fb_info->dev, &device_attrs[i]);
- if (error)
- break;
- }
- if (error) {
- while (--i >= 0)
- device_remove_file(fb_info->dev, &device_attrs[i]);
- fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR;
- }
- return 0;
- }
- /* When cmap is added back in it should be a binary attribute
- * not a text one. Consideration should also be given to converting
- * fbdev to use configfs instead of sysfs */
- static struct device_attribute device_attrs[] = {
- __ATTR(bits_per_pixel, S_IRUGO|S_IWUSR, show_bpp, store_bpp),
- __ATTR(blank, S_IRUGO|S_IWUSR, show_blank, store_blank),
- __ATTR(console, S_IRUGO|S_IWUSR, show_console, store_console),
- __ATTR(cursor, S_IRUGO|S_IWUSR, show_cursor, store_cursor),
- __ATTR(mode, S_IRUGO|S_IWUSR, show_mode, store_mode),
- __ATTR(modes, S_IRUGO|S_IWUSR, show_modes, store_modes),
- __ATTR(pan, S_IRUGO|S_IWUSR, show_pan, store_pan),
- __ATTR(virtual_size, S_IRUGO|S_IWUSR, show_virtual, store_virtual),
- __ATTR(name, S_IRUGO, show_name, NULL),
- __ATTR(stride, S_IRUGO, show_stride, NULL),
- __ATTR(rotate, S_IRUGO|S_IWUSR, show_rotate, store_rotate),
- __ATTR(state, S_IRUGO|S_IWUSR, show_fbstate, store_fbstate),
- #ifdef CONFIG_FB_BACKLIGHT
- __ATTR(bl_curve, S_IRUGO|S_IWUSR, show_bl_curve, store_bl_curve),
- #endif
- };
- int fb_init_device(struct fb_info *fb_info)
- {
- int i, error = 0;
- dev_set_drvdata(fb_info->dev, fb_info);
- fb_info->class_flag |= FB_SYSFS_FLAG_ATTR;
- /*建立设备属性*/
- for (i = 0; i < ARRAY_SIZE(device_attrs); i++) {
- error = device_create_file(fb_info->dev, &device_attrs[i]);
- if (error)
- break;
- }
- if (error) {
- while (--i >= 0)
- device_remove_file(fb_info->dev, &device_attrs[i]);
- fb_info->class_flag &= ~FB_SYSFS_FLAG_ATTR;
- }
- return 0;
- }
- /* When cmap is added back in it should be a binary attribute
- * not a text one. Consideration should also be given to converting
- * fbdev to use configfs instead of sysfs */
- static struct device_attribute device_attrs[] = {
- __ATTR(bits_per_pixel, S_IRUGO|S_IWUSR, show_bpp, store_bpp),
- __ATTR(blank, S_IRUGO|S_IWUSR, show_blank, store_blank),
- __ATTR(console, S_IRUGO|S_IWUSR, show_console, store_console),
- __ATTR(cursor, S_IRUGO|S_IWUSR, show_cursor, store_cursor),
- __ATTR(mode, S_IRUGO|S_IWUSR, show_mode, store_mode),
- __ATTR(modes, S_IRUGO|S_IWUSR, show_modes, store_modes),
- __ATTR(pan, S_IRUGO|S_IWUSR, show_pan, store_pan),
- __ATTR(virtual_size, S_IRUGO|S_IWUSR, show_virtual, store_virtual),
- __ATTR(name, S_IRUGO, show_name, NULL),
- __ATTR(stride, S_IRUGO, show_stride, NULL),
- __ATTR(rotate, S_IRUGO|S_IWUSR, show_rotate, store_rotate),
- __ATTR(state, S_IRUGO|S_IWUSR, show_fbstate, store_fbstate),
- #ifdef CONFIG_FB_BACKLIGHT
- __ATTR(bl_curve, S_IRUGO|S_IWUSR, show_bl_curve, store_bl_curve),
- #endif
- };
我们可以在/sys/class/graphics/fb0下发现这些属性文件。
[[email protected] fb0]#pwd
/sys/class/graphics/fb0
[[email protected] fb0]#ls
bits_per_pixel cursor mode pan state uevent
blank dev modes power stride virtual_size
console device name rotate subsystem
接着看下fb_var_to_videomode和fb_add_videomode函数。
下列代码位于drivers/video/modedb.c和drivers/video/fb.h
- struct fb_videomode {
- const char *name; /* optional */
- u32 refresh; /* optional */
- u32 xres;
- u32 yres;
- u32 pixclock;
- u32 left_margin;
- u32 right_margin;
- u32 upper_margin;
- u32 lower_margin;
- u32 hsync_len;
- u32 vsync_len;
- u32 sync;
- u32 vmode;
- u32 flag;
- };
- /**
- * fb_var_to_videomode - convert fb_var_screeninfo to fb_videomode
- * @mode: pointer to struct fb_videomode
- * @var: pointer to struct fb_var_screeninfo
- */
- void fb_var_to_videomode(struct fb_videomode *mode,
- const struct fb_var_screeninfo *var)
- {
- u32 pixclock, hfreq, htotal, vtotal;
- mode->name = NULL;
- mode->xres = var->xres;
- mode->yres = var->yres;
- mode->pixclock = var->pixclock;
- mode->hsync_len = var->hsync_len;
- mode->vsync_len = var->vsync_len;
- mode->left_margin = var->left_margin;
- mode->right_margin = var->right_margin;
- mode->upper_margin = var->upper_margin;
- mode->lower_margin = var->lower_margin;
- mode->sync = var->sync;
- mode->vmode = var->vmode & FB_VMODE_MASK;
- mode->flag = FB_MODE_IS_FROM_VAR;
- mode->refresh = 0;
- if (!var->pixclock)
- return;
- pixclock = PICOS2KHZ(var->pixclock) * 1000;
- htotal = var->xres + var->right_margin + var->hsync_len +
- var->left_margin;
- vtotal = var->yres + var->lower_margin + var->vsync_len +
- var->upper_margin;
- if (var->vmode & FB_VMODE_INTERLACED)
- vtotal /= 2;
- if (var->vmode & FB_VMODE_DOUBLE)
- vtotal *= 2;
- hfreq = pixclock/htotal;
- mode->refresh = hfreq/vtotal;
- }
- /**
- * fb_add_videomode: adds videomode entry to modelist
- * @mode: videomode to add
- * @head: struct list_head of modelist
- *
- * NOTES:
- * Will only add unmatched mode entries
- */
- int fb_add_videomode(const struct fb_videomode *mode, struct list_head *head)
- {
- struct list_head *pos;
- struct fb_modelist *modelist;d
- struct fb_videomode *m;
- int found = 0;
- /*遍历所有的fb_modelist,查找mode是否存在*/
- list_for_each(pos, head) {
- modelist = list_entry(pos, struct fb_modelist, list);
- m = &modelist->mode;
- if (fb_mode_is_equal(m, mode)) { /*比较两个fb_videomode*/
- found = 1; /*该fb_videomode已存在*/
- break;
- }
- }
- if (!found) { /*不存在*/
- modelist = kmalloc(sizeof(struct fb_modelist), /*分配fb_modelist*/
- GFP_KERNEL);
- if (!modelist)
- return -ENOMEM;
- modelist->mode = *mode; /*保存mode*/
- list_add(&modelist->list, head);/*添加mode至链表中*/
- }
- return 0;
- }
- /**
- * fb_mode_is_equal - compare 2 videomodes
- * @mode1: first videomode
- * @mode2: second videomode
- *
- * RETURNS:
- * 1 if equal, 0 if not
- */
- int fb_mode_is_equal(const struct fb_videomode *mode1,
- const struct fb_videomode *mode2)
- {
- return (mode1->xres == mode2->xres &&
- mode1->yres == mode2->yres &&
- mode1->pixclock == mode2->pixclock &&
- mode1->hsync_len == mode2->hsync_len &&
- mode1->vsync_len == mode2->vsync_len &&
- mode1->left_margin == mode2->left_margin &&
- mode1->right_margin == mode2->right_margin &&
- mode1->upper_margin == mode2->upper_margin &&
- mode1->lower_margin == mode2->lower_margin &&
- mode1->sync == mode2->sync &&
- mode1->vmode == mode2->vmode);
- }
- struct fb_videomode {
- const char *name; /* optional */
- u32 refresh; /* optional */
- u32 xres;
- u32 yres;
- u32 pixclock;
- u32 left_margin;
- u32 right_margin;
- u32 upper_margin;
- u32 lower_margin;
- u32 hsync_len;
- u32 vsync_len;
- u32 sync;
- u32 vmode;
- u32 flag;
- };
- /**
- * fb_var_to_videomode - convert fb_var_screeninfo to fb_videomode
- * @mode: pointer to struct fb_videomode
- * @var: pointer to struct fb_var_screeninfo
- */
- void fb_var_to_videomode(struct fb_videomode *mode,
- const struct fb_var_screeninfo *var)
- {
- u32 pixclock, hfreq, htotal, vtotal;
- mode->name = NULL;
- mode->xres = var->xres;
- mode->yres = var->yres;
- mode->pixclock = var->pixclock;
- mode->hsync_len = var->hsync_len;
- mode->vsync_len = var->vsync_len;
- mode->left_margin = var->left_margin;
- mode->right_margin = var->right_margin;
- mode->upper_margin = var->upper_margin;
- mode->lower_margin = var->lower_margin;
- mode->sync = var->sync;
- mode->vmode = var->vmode & FB_VMODE_MASK;
- mode->flag = FB_MODE_IS_FROM_VAR;
- mode->refresh = 0;
- if (!var->pixclock)
- return;
- pixclock = PICOS2KHZ(var->pixclock) * 1000;
- htotal = var->xres + var->right_margin + var->hsync_len +
- var->left_margin;
- vtotal = var->yres + var->lower_margin + var->vsync_len +
- var->upper_margin;
- if (var->vmode & FB_VMODE_INTERLACED)
- vtotal /= 2;
- if (var->vmode & FB_VMODE_DOUBLE)
- vtotal *= 2;
- hfreq = pixclock/htotal;
- mode->refresh = hfreq/vtotal;
- }
- /**
- * fb_add_videomode: adds videomode entry to modelist
- * @mode: videomode to add
- * @head: struct list_head of modelist
- *
- * NOTES:
- * Will only add unmatched mode entries
- */
- int fb_add_videomode(const struct fb_videomode *mode, struct list_head *head)
- {
- struct list_head *pos;
- struct fb_modelist *modelist;d
- struct fb_videomode *m;
- int found = 0;
- /*遍历所有的fb_modelist,查找mode是否存在*/
- list_for_each(pos, head) {
- modelist = list_entry(pos, struct fb_modelist, list);
- m = &modelist->mode;
- if (fb_mode_is_equal(m, mode)) { /*比较两个fb_videomode*/
- found = 1; /*该fb_videomode已存在*/
- break;
- }
- }
- if (!found) { /*不存在*/
- modelist = kmalloc(sizeof(struct fb_modelist), /*分配fb_modelist*/
- GFP_KERNEL);
- if (!modelist)
- return -ENOMEM;
- modelist->mode = *mode; /*保存mode*/
- list_add(&modelist->list, head);/*添加mode至链表中*/
- }
- return 0;
- }
- /**
- * fb_mode_is_equal - compare 2 videomodes
- * @mode1: first videomode
- * @mode2: second videomode
- *
- * RETURNS:
- * 1 if equal, 0 if not
- */
- int fb_mode_is_equal(const struct fb_videomode *mode1,
- const struct fb_videomode *mode2)
- {
- return (mode1->xres == mode2->xres &&
- mode1->yres == mode2->yres &&
- mode1->pixclock == mode2->pixclock &&
- mode1->hsync_len == mode2->hsync_len &&
- mode1->vsync_len == mode2->vsync_len &&
- mode1->left_margin == mode2->left_margin &&
- mode1->right_margin == mode2->right_margin &&
- mode1->upper_margin == mode2->upper_margin &&
- mode1->lower_margin == mode2->lower_margin &&
- mode1->sync == mode2->sync &&
- mode1->vmode == mode2->vmode);
- }
fb_var_to_videomode函数只是将fb_var_screeninfo结构转换成fb_videomode结构。而fb_add_videomode函数查找是否该fb_videomode已经存在,如果不存在则添加到列表中。
3.4 字符设备方法
在看过framebuffer子系统建立和注册过程后,我们看下framebuffer留给用户空间的API是怎样实现的。
本小结只分析5个常用的方法,即open,release,read,write和ioctl。
因为所有的方法和struct fb_ops定义的方法有紧密的联系,而该结构的定义由驱动程序给出,在这里我们提前看下在驱动中是如何定义的。
下列代码位于drivers/video/s3c2410fb..c
- static struct fb_ops s3c2410fb_ops = {
- .owner = THIS_MODULE,
- .fb_check_var = s3c2410fb_check_var, /*检查变量的合法性*/
- .fb_set_par = s3c2410fb_set_par, /*将参数写入LCD控制器,该函数由帧缓冲核心调用*/
- .fb_blank = s3c2410fb_blank, /*该方法支持显示消隐和去消隐*/
- .fb_setcolreg = s3c2410fb_setcolreg, /*设置颜色寄存器*/
- .fb_fillrect = cfb_fillrect, /*用像素行填充矩形框,通用库函数*/
- .fb_copyarea = cfb_copyarea, /*将屏幕的一个矩形区域复制到另一个区域,通用库函数*/
- .fb_imageblit = cfb_imageblit, /*显示一副图像,通用库函数*/
- };
- static struct fb_ops s3c2410fb_ops = {
- .owner = THIS_MODULE,
- .fb_check_var = s3c2410fb_check_var, /*检查变量的合法性*/
- .fb_set_par = s3c2410fb_set_par, /*将参数写入LCD控制器,该函数由帧缓冲核心调用*/
- .fb_blank = s3c2410fb_blank, /*该方法支持显示消隐和去消隐*/
- .fb_setcolreg = s3c2410fb_setcolreg, /*设置颜色寄存器*/
- .fb_fillrect = cfb_fillrect, /*用像素行填充矩形框,通用库函数*/
- .fb_copyarea = cfb_copyarea, /*将屏幕的一个矩形区域复制到另一个区域,通用库函数*/
- .fb_imageblit = cfb_imageblit, /*显示一副图像,通用库函数*/
- };
最下面的三个方法使用的是内核提供的库函数,而上面4个则是由驱动提供。
3.4.1 open方法
下列代码位于drivers/video/fbmem.c
- static int
- fb_open(struct inode *inode, struct file *file)
- __acquires(&info->lock)
- __releases(&info->lock)
- {
- int fbidx = iminor(inode);
- struct fb_info *info;
- int res = 0;
- if (fbidx >= FB_MAX)
- return -ENODEV;
- info = registered_fb[fbidx]; /*在register_framebuffer函数中已经设置了元素*/
- if (!info)
- request_module("fb%d", fbidx); /*加载模块,这里不加载*/
- info = registered_fb[fbidx];
- if (!info)
- return -ENODEV;
- mutex_lock(&info->lock); /*加锁互斥体*/
- if (!try_module_get(info->fbops->owner)) { /*增加模块引用计数*/
- res = -ENODEV;
- goto out;
- }
- file->private_data = info; /*保存info*/
- if (info->fbops->fb_open) { /*这里fb_open方法为空*/
- res = info->fbops->fb_open(info,1);
- if (res)
- module_put(info->fbops->owner);
- }
- #ifdef CONFIG_FB_DEFERRED_IO
- if (info->fbdefio)
- fb_deferred_io_open(info, inode, file);
- #endif
- out:
- mutex_unlock(&info->lock); /*解锁互斥体*/
- return res;
- }
- static int
- fb_open(struct inode *inode, struct file *file)
- __acquires(&info->lock)
- __releases(&info->lock)
- {
- int fbidx = iminor(inode);
- struct fb_info *info;
- int res = 0;
- if (fbidx >= FB_MAX)
- return -ENODEV;
- info = registered_fb[fbidx]; /*在register_framebuffer函数中已经设置了元素*/
- if (!info)
- request_module("fb%d", fbidx); /*加载模块,这里不加载*/
- info = registered_fb[fbidx];
- if (!info)
- return -ENODEV;
- mutex_lock(&info->lock); /*加锁互斥体*/
- if (!try_module_get(info->fbops->owner)) { /*增加模块引用计数*/
- res = -ENODEV;
- goto out;
- }
- file->private_data = info; /*保存info*/
- if (info->fbops->fb_open) { /*这里fb_open方法为空*/
- res = info->fbops->fb_open(info,1);
- if (res)
- module_put(info->fbops->owner);
- }
- #ifdef CONFIG_FB_DEFERRED_IO
- if (info->fbdefio)
- fb_deferred_io_open(info, inode, file);
- #endif
- out:
- mutex_unlock(&info->lock); /*解锁互斥体*/
- return res;
- }
主要的一个工作就是增加模块引用计数。还有,程序会判断是否fb_open在驱动中给出,如果有则调用该方法。我们已经知道fb_open没有给出。
3.4.2 release方法
下列代码位于drivers/video/fbmem.c
- static int
- fb_release(struct inode *inode, struct file *file)
- __acquires(&info->lock)
- __releases(&info->lock)
- {
- struct fb_info * const info = file->private_data;
- mutex_lock(&info->lock);
- if (info->fbops->fb_release) /*这里fb_release为空*/
- info->fbops->fb_release(info,1);
- module_put(info->fbops->owner); /*减少模块引用计数*/
- mutex_unlock(&info->lock);
- return 0;
- }
- static int
- fb_release(struct inode *inode, struct file *file)
- __acquires(&info->lock)
- __releases(&info->lock)
- {
- struct fb_info * const info = file->private_data;
- mutex_lock(&info->lock);
- if (info->fbops->fb_release) /*这里fb_release为空*/
- info->fbops->fb_release(info,1);
- module_put(info->fbops->owner); /*减少模块引用计数*/
- mutex_unlock(&info->lock);
- return 0;
- }
和open相反,减少模块引用计数。
3.4.3 write方法
通过调用该方法,LCD将显示画面。
下列代码位于drivers/video/fbmem.c
- static ssize_t
- fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
- {
- unsigned long p = *ppos;
- struct inode *inode = file->f_path.dentry->d_inode;
- int fbidx = iminor(inode);
- struct fb_info *info = registered_fb[fbidx];
- u32 *buffer, *src;
- u32 __iomem *dst;
- int c, i, cnt = 0, err = 0;
- unsigned long total_size;
- if (!info || !info->screen_base) /*screen_base在驱动中给出*/
- return -ENODEV;
- if (info->state != FBINFO_STATE_RUNNING)
- return -EPERM;
- if (info->fbops->fb_write) /*没有fb_write方法*/
- return info->fbops->fb_write(info, buf, count, ppos);
- total_size = info->screen_size; /*screen_size没有给出*/
- if (total_size == 0)
- total_size = info->fix.smem_len;/*153600字节,驱动probe方法中计算*/
- if (p > total_size)
- return -EFBIG;
- if (count > total_size) { /*要写入的字节数大于153600*/
- err = -EFBIG; /*file too big*/
- count = total_size;
- }
- if (count + p > total_size) {/*偏移量加上字节数超出了缓冲区*/
- if (!err)
- err = -ENOSPC;
- count = total_size - p;
- }
- /*分配buffer,GFP_KERNEL*/
- buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
- GFP_KERNEL); /
- if (!buffer)
- return -ENOMEM;
- dst = (u32 __iomem *) (info->screen_base + p);/*修改目的指针*/
- if (info->fbops->fb_sync) /*没有定义fb_sync*/
- info->fbops->fb_sync(info);
- while (count) {
- c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
- src = buffer;
- /*从buf(用户空间)拷贝数据到src中,一开始为1页,最后为count字节*/
- if (copy_from_user(src, buf, c)) {
- err = -EFAULT;
- break;
- }
- /*一次for循环,写入4个字节数据到dst处*/
- for (i = c >> 2; i--; )
- fb_writel(*src++, dst++);
- /*最后还有3个,2个或者1个字节*/
- if (c & 3) {
- u8 *src8 = (u8 *) src;
- u8 __iomem *dst8 = (u8 __iomem *) dst;
- /*一次写入一个字节*/
- for (i = c & 3; i--; )
- fb_writeb(*src8++, dst8++);
- dst = (u32 __iomem *) dst8;
- }
- *ppos += c; /*用户空间偏移量增加*/
- buf += c; /*用户空间指针增加*/
- cnt += c; /*修改已发送字节数*/
- count -= c; /*减去1页*/
- }
- kfree(buffer); /*释放buffer*/
- return (cnt) ? cnt : err;
- }
- static ssize_t
- fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
- {
- unsigned long p = *ppos;
- struct inode *inode = file->f_path.dentry->d_inode;
- int fbidx = iminor(inode);
- struct fb_info *info = registered_fb[fbidx];
- u32 *buffer, *src;
- u32 __iomem *dst;
- int c, i, cnt = 0, err = 0;
- unsigned long total_size;
- if (!info || !info->screen_base) /*screen_base在驱动中给出*/
- return -ENODEV;
- if (info->state != FBINFO_STATE_RUNNING)
- return -EPERM;
- if (info->fbops->fb_write) /*没有fb_write方法*/
- return info->fbops->fb_write(info, buf, count, ppos);
- total_size = info->screen_size; /*screen_size没有给出*/
- if (total_size == 0)
- total_size = info->fix.smem_len;/*153600字节,驱动probe方法中计算*/
- if (p > total_size)
- return -EFBIG;
- if (count > total_size) { /*要写入的字节数大于153600*/
- err = -EFBIG; /*file too big*/
- count = total_size;
- }
- if (count + p > total_size) {/*偏移量加上字节数超出了缓冲区*/
- if (!err)
- err = -ENOSPC;
- count = total_size - p;
- }
- /*分配buffer,GFP_KERNEL*/
- buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
- GFP_KERNEL); /
- if (!buffer)
- return -ENOMEM;
- dst = (u32 __iomem *) (info->screen_base + p);/*修改目的指针*/
- if (info->fbops->fb_sync) /*没有定义fb_sync*/
- info->fbops->fb_sync(info);
- while (count) {
- c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
- src = buffer;
- /*从buf(用户空间)拷贝数据到src中,一开始为1页,最后为count字节*/
- if (copy_from_user(src, buf, c)) {
- err = -EFAULT;
- break;
- }
- /*一次for循环,写入4个字节数据到dst处*/
- for (i = c >> 2; i--; )
- fb_writel(*src++, dst++);
- /*最后还有3个,2个或者1个字节*/
- if (c & 3) {
- u8 *src8 = (u8 *) src;
- u8 __iomem *dst8 = (u8 __iomem *) dst;
- /*一次写入一个字节*/
- for (i = c & 3; i--; )
- fb_writeb(*src8++, dst8++);
- dst = (u32 __iomem *) dst8;
- }
- *ppos += c; /*用户空间偏移量增加*/
- buf += c; /*用户空间指针增加*/
- cnt += c; /*修改已发送字节数*/
- count -= c; /*减去1页*/
- }
- kfree(buffer); /*释放buffer*/
- return (cnt) ? cnt : err;
- }
这里,做了一系列的检查之后,开始拷贝数据。这里一个有三个buffer,一个是用户空间提供的buf,一个是在这里新开辟的buffer,还有就是驱动层提供的screen_base。
数据流如下:
用户空间的数据首先被复制到buffer中,然后从buffer中复制到screen_base中,最后被映射到LCD上,LCD就显示响应的画面了。
3.4.4 read方法
该方法用于读取屏幕画面的数据。
read和write类似,只是数据流是反响的,就不多做介绍了。
下列代码位于drivers/video/fbmem.c
- static ssize_t
- fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
- {
- unsigned long p = *ppos;
- struct inode *inode = file->f_path.dentry->d_inode;
- int fbidx = iminor(inode);
- struct fb_info *info = registered_fb[fbidx];
- u32 *buffer, *dst;
- u32 __iomem *src;
- int c, i, cnt = 0, err = 0;
- unsigned long total_size;
- if (!info || ! info->screen_base)
- return -ENODEV;
- if (info->state != FBINFO_STATE_RUNNING)
- return -EPERM;
- if (info->fbops->fb_read) /*没有定义fb_read*/
- return info->fbops->fb_read(info, buf, count, ppos);
- total_size = info->screen_size;
- if (total_size == 0)
- total_size = info->fix.smem_len;
- if (p >= total_size)
- return 0;
- if (count >= total_size)
- count = total_size;
- if (count + p > total_size)
- count = total_size - p;
- buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
- GFP_KERNEL);
- if (!buffer)
- return -ENOMEM;
- src = (u32 __iomem *) (info->screen_base + p);
- if (info->fbops->fb_sync)
- info->fbops->fb_sync(info);/*没有定义fb_sync*/
- while (count) {
- c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
- dst = buffer;
- for (i = c >> 2; i--; )
- *dst++ = fb_readl(src++);
- if (c & 3) {
- u8 *dst8 = (u8 *) dst;
- u8 __iomem *src8 = (u8 __iomem *) src;
- for (i = c & 3; i--;)
- *dst8++ = fb_readb(src8++);
- src = (u32 __iomem *) src8;
- }
- if (copy_to_user(buf, buffer, c)) {
- err = -EFAULT;
- break;
- }
- *ppos += c;
- buf += c;
- cnt += c;
- count -= c;
- }
- kfree(buffer);
- return (err) ? err : cnt;
- }
- static ssize_t
- fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
- {
- unsigned long p = *ppos;
- struct inode *inode = file->f_path.dentry->d_inode;
- int fbidx = iminor(inode);
- struct fb_info *info = registered_fb[fbidx];
- u32 *buffer, *dst;
- u32 __iomem *src;
- int c, i, cnt = 0, err = 0;
- unsigned long total_size;
- if (!info || ! info->screen_base)
- return -ENODEV;
- if (info->state != FBINFO_STATE_RUNNING)
- return -EPERM;
- if (info->fbops->fb_read) /*没有定义fb_read*/
- return info->fbops->fb_read(info, buf, count, ppos);
- total_size = info->screen_size;
- if (total_size == 0)
- total_size = info->fix.smem_len;
- if (p >= total_size)
- return 0;
- if (count >= total_size)
- count = total_size;
- if (count + p > total_size)
- count = total_size - p;
- buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count,
- GFP_KERNEL);
- if (!buffer)
- return -ENOMEM;
- src = (u32 __iomem *) (info->screen_base + p);
- if (info->fbops->fb_sync)
- info->fbops->fb_sync(info);/*没有定义fb_sync*/
- while (count) {
- c = (count > PAGE_SIZE) ? PAGE_SIZE : count;
- dst = buffer;
- for (i = c >> 2; i--; )
- *dst++ = fb_readl(src++);
- if (c & 3) {
- u8 *dst8 = (u8 *) dst;
- u8 __iomem *src8 = (u8 __iomem *) src;
- for (i = c & 3; i--;)
- *dst8++ = fb_readb(src8++);
- src = (u32 __iomem *) src8;
- }
- if (copy_to_user(buf, buffer, c)) {
- err = -EFAULT;
- break;
- }
- *ppos += c;
- buf += c;
- cnt += c;
- count -= c;
- }
- kfree(buffer);
- return (err) ? err : cnt;
- }
3.4.5 ioctl方法
这里只是简单的看下ioctl方法,这个函数调用很多其他的函数,详细的请自己看吧。
下列代码位于drivers/video/fbmem.c
- static long fb_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
- {
- /*获取inode,再获取对应的fb_info*/
- struct inode *inode = file->f_path.dentry->d_inode;
- int fbidx = iminor(inode);
- struct fb_info *info = registered_fb[fbidx];
- return do_fb_ioctl(info, cmd, arg);
- }
- static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
- unsigned long arg)
- {
- struct fb_ops *fb;
- struct fb_var_screeninfo var;
- struct fb_fix_screeninfo fix;
- struct fb_con2fbmap con2fb;
- struct fb_cmap cmap_from;
- struct fb_cmap_user cmap;
- struct fb_event event;
- void __user *argp = (void __user *)arg;
- long ret = 0;
- switch (cmd) {
- /*获取fb_var_screeninfo*/
- case FBIOGET_VSCREENINFO:
- if (!lock_fb_info(info)) /*加锁互斥体info->lock*/
- return -ENODEV;
- var = info->var; /*复制var*/
- unlock_fb_info(info);
- ret = copy_to_user(argp, &var, sizeof(var)) ? -EFAULT : 0; /*复制var到用户空间*/
- break;
- /*设置fb_var_screeninfo*/
- case FBIOPUT_VSCREENINFO:
- if (copy_from_user(&var, argp, sizeof(var))) /*从用户空间获取var*/
- return -EFAULT;
- if (!lock_fb_info(info))
- return -ENODEV;
- acquire_console_sem();
- info->flags |= FBINFO_MISC_USEREVENT;
- ret = fb_set_var(info, &var); /*设置var*/
- info->flags &= ~FBINFO_MISC_USEREVENT;
- release_console_sem();
- unlock_fb_info(info);
- if (!ret && copy_to_user(argp, &var, sizeof(var)))
- ret = -EFAULT;
- break;
- /*获取fb_fix_screeninfo*/ /*fix为不可改变信息,只能获取,不能设置*/
- case FBIOGET_FSCREENINFO:
- if (!lock_fb_info(info))
- return -ENODEV;
- fix = info->fix;
- unlock_fb_info(info);
- ret = copy_to_user(argp, &fix, sizeof(fix)) ? -EFAULT : 0;
- break;
- /*设置fb_cmap*/
- case FBIOPUTCMAP:
- if (copy_from_user(&cmap, argp, sizeof(cmap)))
- return -EFAULT;
- ret = fb_set_user_cmap(&cmap, info); /*设置fb_cmap*/
- break;
- /*获取fb_cmap*/
- case FBIOGETCMAP:
- if (copy_from_user(&cmap, argp, sizeof(cmap)))
- return -EFAULT;
- if (!lock_fb_info(info))
- return -ENODEV;
- cmap_from = info->cmap;
- unlock_fb_info(info);
- ret = fb_cmap_to_user(&cmap_from, &cmap);/*获取fb_cmp*/
- break;
- case FBIOPAN_DISPLAY:
- if (copy_from_user(&var, argp, sizeof(var)))
- return -EFAULT;
- if (!lock_fb_info(info))
- return -ENODEV;
- acquire_console_sem();
- ret = fb_pan_display(info, &var);
- release_console_sem();
- unlock_fb_info(info);
- if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))
- return -EFAULT;
- break;
- case FBIO_CURSOR:
- ret = -EINVAL;
- break;
- case FBIOGET_CON2FBMAP:
- if (copy_from_user(&con2fb, argp, sizeof(con2fb)))
- return -EFAULT;
- if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
- return -EINVAL;
- con2fb.framebuffer = -1;
- event.data = &con2fb;
- if (!lock_fb_info(info))
- return -ENODEV;
- event.info = info;
- fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event);
- unlock_fb_info(info);
- ret = copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : 0;
- break;
- case FBIOPUT_CON2FBMAP:
- if (copy_from_user(&con2fb, argp, sizeof(con2fb)))
- return -EFAULT;
- if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
- return -EINVAL;
- if (con2fb.framebuffer < 0 || con2fb.framebuffer >= FB_MAX)
- return -EINVAL;
- if (!registered_fb[con2fb.framebuffer])
- request_module("fb%d", con2fb.framebuffer);
- if (!registered_fb[con2fb.framebuffer]) {
- ret = -EINVAL;
- break;
- }
- event.data = &con2fb;
- if (!lock_fb_info(info))
- return -ENODEV;
- event.info = info;
- ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event);
- unlock_fb_info(info);
- break;
- case FBIOBLANK:
- if (!lock_fb_info(info))
- return -ENODEV;
- acquire_console_sem();
- info->flags |= FBINFO_MISC_USEREVENT;
- ret = fb_blank(info, arg); ?*最后调用驱动提供的s3c2410fb_blank*/
- info->flags &= ~FBINFO_MISC_USEREVENT;
- release_console_sem();
- unlock_fb_info(info);
- break;
- default:
- if (!lock_fb_info(info))
- return -ENODEV;
- fb = info->fbops;
- if (fb->fb_ioctl) /*fb_ioctl为空*/
- ret = fb->fb_ioctl(info, cmd, arg);
- else
- ret = -ENOTTY;
- unlock_fb_info(info);
- }
- return ret;
- }
- static long fb_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
- {
- /*获取inode,再获取对应的fb_info*/
- struct inode *inode = file->f_path.dentry->d_inode;
- int fbidx = iminor(inode);
- struct fb_info *info = registered_fb[fbidx];
- return do_fb_ioctl(info, cmd, arg);
- }
- static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
- unsigned long arg)
- {
- struct fb_ops *fb;
- struct fb_var_screeninfo var;
- struct fb_fix_screeninfo fix;
- struct fb_con2fbmap con2fb;
- struct fb_cmap cmap_from;
- struct fb_cmap_user cmap;
- struct fb_event event;
- void __user *argp = (void __user *)arg;
- long ret = 0;
- switch (cmd) {
- /*获取fb_var_screeninfo*/
- case FBIOGET_VSCREENINFO:
- if (!lock_fb_info(info)) /*加锁互斥体info->lock*/
- return -ENODEV;
- var = info->var; /*复制var*/
- unlock_fb_info(info);
- ret = copy_to_user(argp, &var, sizeof(var)) ? -EFAULT : 0; /*复制var到用户空间*/
- break;
- /*设置fb_var_screeninfo*/
- case FBIOPUT_VSCREENINFO:
- if (copy_from_user(&var, argp, sizeof(var))) /*从用户空间获取var*/
- return -EFAULT;
- if (!lock_fb_info(info))
- return -ENODEV;
- acquire_console_sem();
- info->flags |= FBINFO_MISC_USEREVENT;
- ret = fb_set_var(info, &var); /*设置var*/
- info->flags &= ~FBINFO_MISC_USEREVENT;
- release_console_sem();
- unlock_fb_info(info);
- if (!ret && copy_to_user(argp, &var, sizeof(var)))
- ret = -EFAULT;
- break;
- /*获取fb_fix_screeninfo*/ /*fix为不可改变信息,只能获取,不能设置*/
- case FBIOGET_FSCREENINFO:
- if (!lock_fb_info(info))
- return -ENODEV;
- fix = info->fix;
- unlock_fb_info(info);
- ret = copy_to_user(argp, &fix, sizeof(fix)) ? -EFAULT : 0;
- break;
- /*设置fb_cmap*/
- case FBIOPUTCMAP:
- if (copy_from_user(&cmap, argp, sizeof(cmap)))
- return -EFAULT;
- ret = fb_set_user_cmap(&cmap, info); /*设置fb_cmap*/
- break;
- /*获取fb_cmap*/
- case FBIOGETCMAP:
- if (copy_from_user(&cmap, argp, sizeof(cmap)))
- return -EFAULT;
- if (!lock_fb_info(info))
- return -ENODEV;
- cmap_from = info->cmap;
- unlock_fb_info(info);
- ret = fb_cmap_to_user(&cmap_from, &cmap);/*获取fb_cmp*/
- break;
- case FBIOPAN_DISPLAY:
- if (copy_from_user(&var, argp, sizeof(var)))
- return -EFAULT;
- if (!lock_fb_info(info))
- return -ENODEV;
- acquire_console_sem();
- ret = fb_pan_display(info, &var);
- release_console_sem();
- unlock_fb_info(info);
- if (ret == 0 && copy_to_user(argp, &var, sizeof(var)))
- return -EFAULT;
- break;
- case FBIO_CURSOR:
- ret = -EINVAL;
- break;
- case FBIOGET_CON2FBMAP:
- if (copy_from_user(&con2fb, argp, sizeof(con2fb)))
- return -EFAULT;
- if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
- return -EINVAL;
- con2fb.framebuffer = -1;
- event.data = &con2fb;
- if (!lock_fb_info(info))
- return -ENODEV;
- event.info = info;
- fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event);
- unlock_fb_info(info);
- ret = copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : 0;
- break;
- case FBIOPUT_CON2FBMAP:
- if (copy_from_user(&con2fb, argp, sizeof(con2fb)))
- return -EFAULT;
- if (con2fb.console < 1 || con2fb.console > MAX_NR_CONSOLES)
- return -EINVAL;
- if (con2fb.framebuffer < 0 || con2fb.framebuffer >= FB_MAX)
- return -EINVAL;
- if (!registered_fb[con2fb.framebuffer])
- request_module("fb%d", con2fb.framebuffer);
- if (!registered_fb[con2fb.framebuffer]) {
- ret = -EINVAL;
- break;
- }
- event.data = &con2fb;
- if (!lock_fb_info(info))
- return -ENODEV;
- event.info = info;
- ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event);
- unlock_fb_info(info);
- break;
- case FBIOBLANK:
- if (!lock_fb_info(info))
- return -ENODEV;
- acquire_console_sem();
- info->flags |= FBINFO_MISC_USEREVENT;
- ret = fb_blank(info, arg); ?*最后调用驱动提供的s3c2410fb_blank*/
- info->flags &= ~FBINFO_MISC_USEREVENT;
- release_console_sem();
- unlock_fb_info(info);
- break;
- default:
- if (!lock_fb_info(info))
- return -ENODEV;
- fb = info->fbops;
- if (fb->fb_ioctl) /*fb_ioctl为空*/
- ret = fb->fb_ioctl(info, cmd, arg);
- else
- ret = -ENOTTY;
- unlock_fb_info(info);
- }
- return ret;
- }
正如2.2小结所说的,fb_fix_screeninfo只能获取不能设置,因此,ioctl只提供了获取fb_fix_screeninfo的方法,而没有提供设置fb_fix_screeninfo的方法。
3.5 小结
本节对frambuffer的核心层进行了介绍。包括frambuffer子系统的创建,frambuffer的注册和提供给用户空间的5个API函数。下面开始介绍驱动层。
4. 驱动层
本节将开始介绍S3C2440的frambuffer驱动,该驱动源码位于drivers/video/s3c2410fb.c
首先来看下驱动模块的初始化和清除函数。
4.1 s3c2410fb_init和s3c2410fb_cleanup
- static struct platform_driver s3c2410fb_driver = {
- .probe = s3c2410fb_probe,
- .remove = s3c2410fb_remove,
- .suspend = s3c2410fb_suspend,
- .resume = s3c2410fb_resume,
- .driver = {
- .name = "s3c2410-lcd",
- .owner = THIS_MODULE,
- },
- };
- int __init s3c2410fb_init(void)
- {
- int ret = platform_driver_register(&s3c2410fb_driver);
- if (ret == 0)
- ret = platform_driver_register(&s3c2412fb_driver);;
- return ret;
- }
- static void __exit s3c2410fb_cleanup(void)
- {
- platform_driver_unregister(&s3c2410fb_driver);
- platform_driver_unregister(&s3c2412fb_driver);
- }
- module_init(s3c2410fb_init);
- module_exit(s3c2410fb_cleanup);
- static struct platform_driver s3c2410fb_driver = {
- .probe = s3c2410fb_probe,
- .remove = s3c2410fb_remove,
- .suspend = s3c2410fb_suspend,
- .resume = s3c2410fb_resume,
- .driver = {
- .name = "s3c2410-lcd",
- .owner = THIS_MODULE,
- },
- };
- int __init s3c2410fb_init(void)
- {
- int ret = platform_driver_register(&s3c2410fb_driver);
- if (ret == 0)
- ret = platform_driver_register(&s3c2412fb_driver);;
- return ret;
- }
- static void __exit s3c2410fb_cleanup(void)
- {
- platform_driver_unregister(&s3c2410fb_driver);
- platform_driver_unregister(&s3c2412fb_driver);
- }
- module_init(s3c2410fb_init);
- module_exit(s3c2410fb_cleanup);
当platform_driver_register调用的最后会调用probe方法。接下来就来看看probe方法。
4.2 probe方法
- struct s3c2410fb_info {
- struct device *dev;
- struct clk *clk;
- struct resource *mem;
- void __iomem *io; /*虚拟地址*/
- void __iomem *irq_base;
- enum s3c_drv_type drv_type;
- struct s3c2410fb_hw regs;
- unsigned int palette_ready;
- /* keep these registers in case we need to re-write palette */
- u32 palette_buffer[256];
- u32 pseudo_pal[16];
- };
- struct s3c2410fb_mach_info {
- struct s3c2410fb_display *displays; /* attached diplays info */
- unsigned num_displays; /* number of defined displays */
- unsigned default_display;
- /* GPios */
- unsigned long gpcup;
- unsigned long gpcup_mask;
- unsigned long gpccon;
- unsigned long gpccon_mask;
- unsigned long gpdup;
- unsigned long gpdup_mask;
- unsigned long gpdcon;
- unsigned long gpdcon_mask;
- /* lpc3600 control register */
- unsigned long lpcsel;
- };
- /* LCD description */
- struct s3c2410fb_display {
- /* LCD type */
- unsigned type;
- /* Screen size */
- unsigned short width;
- unsigned short height;
- /* Screen info */
- unsigned short xres;
- unsigned short yres;
- unsigned short bpp;
- unsigned pixclock; /* pixclock in picoseconds */
- unsigned short left_margin; /* value in pixels (TFT) or HCLKs (STN) */
- unsigned short right_margin; /* value in pixels (TFT) or HCLKs (STN) */
- unsigned short hsync_len; /* value in pixels (TFT) or HCLKs (STN) */
- unsigned short upper_margin; /* value in lines (TFT) or 0 (STN) */
- unsigned short lower_margin; /* value in lines (TFT) or 0 (STN) */
- unsigned short vsync_len; /* value in lines (TFT) or 0 (STN) */
- /* lcd configuration registers */
- unsigned long lcdcon5;
- };
- static int __init s3c24xxfb_probe(struct platform_device *pdev,
- enum s3c_drv_type drv_type)
- {
- struct s3c2410fb_info *info;
- struct s3c2410fb_display *display;
- struct fb_info *fbinfo;
- struct s3c2410fb_mach_info *mach_info;
- struct resource *res;
- int ret;
- int irq;
- int i;
- int size;
- u32 lcdcon1;
- /*dev.platform_data由函数s3c24xx_fb_set_platdata(mach-smdk2410.c)设置,指向s3c2410fb_mach_info*/
- mach_info = pdev->dev.platform_data;
- if (mach_info == NULL) {
- dev_err(&pdev->dev,
- "no platform data for lcd, cannot attach\n");
- return -EINVAL;
- }
- /*在mach-smdk2440.c中,default_display=0, num_displays=1*/
- if (mach_info->default_display >= mach_info->num_displays) {
- dev_err(&pdev->dev, "default is %d but only %d displays\n",
- mach_info->default_display, mach_info->num_displays);
- return -EINVAL;
- }
- display = mach_info->displays + mach_info->default_display;
- irq = platform_get_irq(pdev, 0); /*获取IRQ号,16号中断*/
- if (irq < 0) {
- dev_err(&pdev->dev, "no irq for device\n");
- return -ENOENT;
- }
- /*分配struct fb_info 其中包括sizeof字节的私有数据区*/
- fbinfo = framebuffer_alloc(sizeof(struct s3c2410fb_info), &pdev->dev);
- if (!fbinfo)
- return -ENOMEM;
- platform_set_drvdata(pdev, fbinfo); /*让platform_device->dev.driver_data指向struct fb_info*/
- info = fbinfo->par; /*par指向s3c2410fb_info*/
- info->dev = &pdev->dev;
- info->drv_type = drv_type;
- res = platform_get_resource(pdev, IORESOURCE_MEM, 0);/*获取平台资源*/
- if (res == NULL) {
- dev_err(&pdev->dev, "failed to get memory registers\n");
- ret = -ENXIO;
- goto dealloc_fb;
- }
- size = (res->end - res->start) + 1; /*IO内存申请*/
- info->mem = request_mem_region(res->start, size, pdev->name);
- if (info->mem == NULL) {
- dev_err(&pdev->dev, "failed to get memory region\n");
- ret = -ENOENT;
- goto dealloc_fb;
- }
- info->io = ioremap(res->start, size); /*IO内存映射,获取lcd第一个寄存器的映射地址*/
- if (info->io == NULL) {
- dev_err(&pdev->dev, "ioremap() of registers failed\n");
- ret = -ENXIO;
- goto release_mem;
- }
- /*irq_base对应的物理地址是0X4D00 0054(寄存器LCDINTPND)*/
- info->irq_base = info->io + ((drv_type == DRV_S3C2412) ? S3C2412_LCDINTBASE : S3C2410_LCDINTBASE);
- dprintk("devinit\n");
- strcpy(fbinfo->fix.id, driver_name); /*复制名字*/
- /* Stop the video */
- lcdcon1 = readl(info->io + S3C2410_LCDCON1);
- writel(lcdcon1 & ~S3C2410_LCDCON1_ENVID, info->io + S3C2410_LCDCON1); /*禁止LCD*/
- fbinfo->fix.type = FB_TYPE_PACKED_PIXELS;
- fbinfo->fix.type_aux = 0;
- fbinfo->fix.xpanstep = 0;
- fbinfo->fix.ypanstep = 0;
- fbinfo->fix.ywrapstep = 0;
- fbinfo->fix.accel = FB_ACCEL_NONE; /* no hardware accelerator */
- fbinfo->var.nonstd = 0;
- fbinfo->var.activate = FB_ACTIVATE_NOW;
- fbinfo->var.accel_flags = 0;
- fbinfo->var.vmode = FB_VMODE_NONINTERLACED;
- fbinfo->fbops = &s3c2410fb_ops;
- fbinfo->flags = FBINFO_FLAG_DEFAULT;
- fbinfo->pseudo_palette = &info->pseudo_pal;
- for (i = 0; i < 256; i++)
- info->palette_buffer[i] = PALETTE_BUFF_CLEAR;
- ret = request_irq(irq, s3c2410fb_irq, IRQF_DISABLED, pdev->name, info); /*申请IRQ,快速中断*/
- if (ret) {
- dev_err(&pdev->dev, "cannot get irq %d - err %d\n", irq, ret);
- ret = -EBUSY;
- goto release_regs;
- }
- info->clk = clk_get(NULL, "lcd"); /*获取时钟信息*/
- if (!info->clk || IS_ERR(info->clk)) {
- printk(KERN_ERR "failed to get lcd clock source\n");
- ret = -ENOENT;
- goto release_irq;
- }
- clk_enable(info->clk); /*使能时钟*/
- dprintk("got and enabled clock\n");
- msleep(1);
- /* find maximum required memory size for display */
- /*在多个屏幕中,找出需要的最大memory*/
- for (i = 0; i < mach_info->num_displays; i++) {
- unsigned long smem_len = mach_info->displays[i].xres;
- /*所需的memory空间 = xres * yres * bpp / 8*/
- smem_len *= mach_info->displays[i].yres;
- smem_len *= mach_info->displays[i].bpp;
- smem_len >>= 3;
- if (fbinfo->fix.smem_len < smem_len)
- fbinfo->fix.smem_len = smem_len;
- }
- /* Initialize video memory */ /*根据上面fix.smem_len的大小,获取DMA映射内存,一致性映射方式*/
- ret = s3c2410fb_map_video_memory(fbinfo);
- if (ret) {
- printk(KERN_ERR "Failed to allocate video RAM: %d\n", ret);
- ret = -ENOMEM;
- goto release_clock;
- }
- dprintk("got video memory\n");
- fbinfo->var.xres = display->xres; /*320*/
- fbinfo->var.yres = display->yres; /*240*/
- fbinfo->var.bits_per_pixel = display->bpp; /*16*/
- s3c2410fb_init_registers(fbinfo); /*LCD寄存器初始化*/
- s3c2410fb_check_var(&fbinfo->var, fbinfo);
- ret = register_framebuffer(fbinfo); /*注册framebuffer*/
- if (ret < 0) {
- printk(KERN_ERR "Failed to register framebuffer device: %d\n",ret);
- goto free_video_memory;
- }
- /* create device files */
- ret = device_create_file(&pdev->dev, &dev_attr_debug); /*添加设备属性*/
- if (ret) {
- printk(KERN_ERR "failed to add debug attribute\n");
- }
- printk(KERN_INFO "fb%d: %s frame buffer device\n",
- fbinfo->node, fbinfo->fix.id);
- return 0;
- /*一旦某个步骤发生错误,以注册的相反顺序开始注销*/
- free_video_memory:
- s3c2410fb_unmap_video_memory(fbinfo);
- release_clock:
- clk_disable(info->clk);
- clk_put(info->clk);
- release_irq:
- free_irq(irq, info);
- release_regs:
- iounmap(info->io);
- release_mem:
- release_resource(info->mem);
- kfree(info->mem);
- dealloc_fb:
- platform_set_drvdata(pdev, NULL);
- framebuffer_release(fbinfo);
- return ret;
- }
- struct s3c2410fb_info {
- struct device *dev;
- struct clk *clk;
- struct resource *mem;
- void __iomem *io; /*虚拟地址*/
- void __iomem *irq_base;
- enum s3c_drv_type drv_type;
- struct s3c2410fb_hw regs;
- unsigned int palette_ready;
- /* keep these registers in case we need to re-write palette */
- u32 palette_buffer[256];
- u32 pseudo_pal[16];
- };
- struct s3c2410fb_mach_info {
- struct s3c2410fb_display *displays; /* attached diplays info */
- unsigned num_displays; /* number of defined displays */
- unsigned default_display;
- /* GPIOs */
- unsigned long gpcup;
- unsigned long gpcup_mask;
- unsigned long gpccon;
- unsigned long gpccon_mask;
- unsigned long gpdup;
- unsigned long gpdup_mask;
- unsigned long gpdcon;
- unsigned long gpdcon_mask;
- /* lpc3600 control register */
- unsigned long lpcsel;
- };
- /* LCD description */
- struct s3c2410fb_display {
- /* LCD type */
- unsigned type;
- /* Screen size */
- unsigned short width;
- unsigned short height;
- /* Screen info */
- unsigned short xres;
- unsigned short yres;
- unsigned short bpp;
- unsigned pixclock; /* pixclock in picoseconds */
- unsigned short left_margin; /* value in pixels (TFT) or HCLKs (STN) */
- unsigned short right_margin; /* value in pixels (TFT) or HCLKs (STN) */
- unsigned short hsync_len; /* value in pixels (TFT) or HCLKs (STN) */
- unsigned short upper_margin; /* value in lines (TFT) or 0 (STN) */
- unsigned short lower_margin; /* value in lines (TFT) or 0 (STN) */
- unsigned short vsync_len; /* value in lines (TFT) or 0 (STN) */
- /* lcd configuration registers */
- unsigned long lcdcon5;
- };
- static int __init s3c24xxfb_probe(struct platform_device *pdev,
- enum s3c_drv_type drv_type)
- {
- struct s3c2410fb_info *info;
- struct s3c2410fb_display *display;
- struct fb_info *fbinfo;
- struct s3c2410fb_mach_info *mach_info;
- struct resource *res;
- int ret;
- int irq;
- int i;
- int size;
- u32 lcdcon1;
- /*dev.platform_data由函数s3c24xx_fb_set_platdata(mach-smdk2410.c)设置,指向s3c2410fb_mach_info*/
- mach_info = pdev->dev.platform_data;
- if (mach_info == NULL) {
- dev_err(&pdev->dev,
- "no platform data for lcd, cannot attach\n");
- return -EINVAL;
- }
- /*在mach-smdk2440.c中,default_display=0, num_displays=1*/
- if (mach_info->default_display >= mach_info->num_displays) {
- dev_err(&pdev->dev, "default is %d but only %d displays\n",
- mach_info->default_display, mach_info->num_displays);
- return -EINVAL;
- }
- display = mach_info->displays + mach_info->default_display;
- irq = platform_get_irq(pdev, 0); /*获取IRQ号,16号中断*/
- if (irq < 0) {
- dev_err(&pdev->dev, "no irq for device\n");
- return -ENOENT;
- }
- /*分配struct fb_info 其中包括sizeof字节的私有数据区*/
- fbinfo = framebuffer_alloc(sizeof(struct s3c2410fb_info), &pdev->dev);
- if (!fbinfo)
- return -ENOMEM;
- platform_set_drvdata(pdev, fbinfo); /*让platform_device->dev.driver_data指向struct fb_info*/
- info = fbinfo->par; /*par指向s3c2410fb_info*/
- info->dev = &pdev->dev;
- info->drv_type = drv_type;
- res = platform_get_resource(pdev, IORESOURCE_MEM, 0);/*获取平台资源*/
- if (res == NULL) {
- dev_err(&pdev->dev, "failed to get memory registers\n");
- ret = -ENXIO;
- goto dealloc_fb;
- }
- size = (res->end - res->start) + 1; /*IO内存申请*/
- info->mem = request_mem_region(res->start, size, pdev->name);
- if (info->mem == NULL) {
- dev_err(&pdev->dev, "failed to get memory region\n");
- ret = -ENOENT;
- goto dealloc_fb;
- }
- info->io = ioremap(res->start, size); /*IO内存映射,获取lcd第一个寄存器的映射地址*/
- if (info->io == NULL) {
- dev_err(&pdev->dev, "ioremap() of registers failed\n");
- ret = -ENXIO;
- goto release_mem;
- }
- /*irq_base对应的物理地址是0X4D00 0054(寄存器LCDINTPND)*/
- info->irq_base = info->io + ((drv_type == DRV_S3C2412) ? S3C2412_LCDINTBASE : S3C2410_LCDINTBASE);
- dprintk("devinit\n");
- strcpy(fbinfo->fix.id, driver_name); /*复制名字*/
- /* Stop the video */
- lcdcon1 = readl(info->io + S3C2410_LCDCON1);
- writel(lcdcon1 & ~S3C2410_LCDCON1_ENVID, info->io + S3C2410_LCDCON1); /*禁止LCD*/
- fbinfo->fix.type = FB_TYPE_PACKED_PIXELS;
- fbinfo->fix.type_aux = 0;
- fbinfo->fix.xpanstep = 0;
- fbinfo->fix.ypanstep = 0;
- fbinfo->fix.ywrapstep = 0;
- fbinfo->fix.accel = FB_ACCEL_NONE; /* no hardware accelerator */
- fbinfo->var.nonstd = 0;
- fbinfo->var.activate = FB_ACTIVATE_NOW;
- fbinfo->var.accel_flags = 0;
- fbinfo->var.vmode = FB_VMODE_NONINTERLACED;
- fbinfo->fbops = &s3c2410fb_ops;
- fbinfo->flags = FBINFO_FLAG_DEFAULT;
- fbinfo->pseudo_palette = &info->pseudo_pal;
- for (i = 0; i < 256; i++)
- info->palette_buffer[i] = PALETTE_BUFF_CLEAR;
- ret = request_irq(irq, s3c2410fb_irq, IRQF_DISABLED, pdev->name, info); /*申请IRQ,快速中断*/
- if (ret) {
- dev_err(&pdev->dev, "cannot get irq %d - err %d\n", irq, ret);
- ret = -EBUSY;
- goto release_regs;
- }
- info->clk = clk_get(NULL, "lcd"); /*获取时钟信息*/
- if (!info->clk || IS_ERR(info->clk)) {
- printk(KERN_ERR "failed to get lcd clock source\n");
- ret = -ENOENT;
- goto release_irq;
- }
- clk_enable(info->clk); /*使能时钟*/
- dprintk("got and enabled clock\n");
- msleep(1);
- /* find maximum required memory size for display */
- /*在多个屏幕中,找出需要的最大memory*/
- for (i = 0; i < mach_info->num_displays; i++) {
- unsigned long smem_len = mach_info->displays[i].xres;
- /*所需的memory空间 = xres * yres * bpp / 8*/
- smem_len *= mach_info->displays[i].yres;
- smem_len *= mach_info->displays[i].bpp;
- smem_len >>= 3;
- if (fbinfo->fix.smem_len < smem_len)
- fbinfo->fix.smem_len = smem_len;
- }
- /* Initialize video memory */ /*根据上面fix.smem_len的大小,获取DMA映射内存,一致性映射方式*/
- ret = s3c2410fb_map_video_memory(fbinfo);
- if (ret) {
- printk(KERN_ERR "Failed to allocate video RAM: %d\n", ret);
- ret = -ENOMEM;
- goto release_clock;
- }
- dprintk("got video memory\n");
- fbinfo->var.xres = display->xres; /*320*/
- fbinfo->var.yres = display->yres; /*240*/
- fbinfo->var.bits_per_pixel = display->bpp; /*16*/
- s3c2410fb_init_registers(fbinfo); /*LCD寄存器初始化*/
- s3c2410fb_check_var(&fbinfo->var, fbinfo);
- ret = register_framebuffer(fbinfo); /*注册framebuffer*/
- if (ret < 0) {
- printk(KERN_ERR "Failed to register framebuffer device: %d\n",ret);
- goto free_video_memory;
- }
- /* create device files */
- ret = device_create_file(&pdev->dev, &dev_attr_debug); /*添加设备属性*/
- if (ret) {
- printk(KERN_ERR "failed to add debug attribute\n");
- }
- printk(KERN_INFO "fb%d: %s frame buffer device\n",
- fbinfo->node, fbinfo->fix.id);
- return 0;
- /*一旦某个步骤发生错误,以注册的相反顺序开始注销*/
- free_video_memory:
- s3c2410fb_unmap_video_memory(fbinfo);
- release_clock:
- clk_disable(info->clk);
- clk_put(info->clk);
- release_irq:
- free_irq(irq, info);
- release_regs:
- iounmap(info->io);
- release_mem:
- release_resource(info->mem);
- kfree(info->mem);
- dealloc_fb:
- platform_set_drvdata(pdev, NULL);
- framebuffer_release(fbinfo);
- return ret;
- }
这里使用了三个新的数据结构。s3c2410fb_info是驱动程序使用的,里面将保存所有驱动程序所要使用的资源等。而s3c2410fb_display和s3c2410fb_mach_info,是由板级信息,通过platform总线添加到内核中。
s3c2410fb_display中的成员将被复制到fb_var_screeninfo结构中。
该板级信息的定义在arch/arm/mach-s3c2440/mach-smdk2440.c中,来看下
- static struct s3c2410fb_display smdk2440_lcd_cfg __initdata = {
- .lcdcon5 = S3C2410_LCDCON5_FRM565 |
- S3C2410_LCDCON5_INVVLINE |
- S3C2410_LCDCON5_INVVFRAME |
- S3C2410_LCDCON5_PWREN |
- S3C2410_LCDCON5_HWSWP,
- .type = S3C2410_LCDCON1_TFT,
- .width = 320,//240,
- .height = 240,//320,
- .pixclock = 149000,//166667, /* HCLK 60 MHz, divisor 10 */
- .xres = 320,//240,
- .yres = 240,//320,
- .bpp = 16,
- .left_margin = 20,
- .right_margin = 38,//8,
- .hsync_len = 30,//4,
- .upper_margin = 15,//8,
- .lower_margin = 12,//7,
- .vsync_len = 3,//4,
- };
- static struct s3c2410fb_mach_info smdk2440_fb_info __initdata = {
- .displays = &smdk2440_lcd_cfg,
- .num_displays = 1,
- .default_display = 0,
- #if 0
- /* currently setup by downloader */
- .gpccon = 0xaa940659,
- .gpccon_mask = 0xffffffff,
- .gpcup = 0x0000ffff,
- .gpcup_mask = 0xffffffff,
- .gpdcon = 0xaa84aaa0,
- .gpdcon_mask = 0xffffffff,
- .gpdup = 0x0000faff,
- .gpdup_mask = 0xffffffff,
- #endif
- //no
- // .lpcsel = ((0xCE6) & ~7) | 1<<4,
- };
- static struct s3c2410fb_display smdk2440_lcd_cfg __initdata = {
- .lcdcon5 = S3C2410_LCDCON5_FRM565 |
- S3C2410_LCDCON5_INVVLINE |
- S3C2410_LCDCON5_INVVFRAME |
- S3C2410_LCDCON5_PWREN |
- S3C2410_LCDCON5_HWSWP,
- .type = S3C2410_LCDCON1_TFT,
- .width = 320,//240,
- .height = 240,//320,
- .pixclock = 149000,//166667, /* HCLK 60 MHz, divisor 10 */
- .xres = 320,//240,
- .yres = 240,//320,
- .bpp = 16,
- .left_margin = 20,
- .right_margin = 38,//8,
- .hsync_len = 30,//4,
- .upper_margin = 15,//8,
- .lower_margin = 12,//7,
- .vsync_len = 3,//4,
- };
- static struct s3c2410fb_mach_info smdk2440_fb_info __initdata = {
- .displays = &smdk2440_lcd_cfg,
- .num_displays = 1,
- .default_display = 0,
- #if 0
- /* currently setup by downloader */
- .gpccon = 0xaa940659,
- .gpccon_mask = 0xffffffff,
- .gpcup = 0x0000ffff,
- .gpcup_mask = 0xffffffff,
- .gpdcon = 0xaa84aaa0,
- .gpdcon_mask = 0xffffffff,
- .gpdup = 0x0000faff,
- .gpdup_mask = 0xffffffff,
- #endif
- //no
- // .lpcsel = ((0xCE6) & ~7) | 1<<4,
- };
这里NOTE:每个LCD屏幕的参数不一样,因此上面的参数会有所不同,这是需要移植的地方。
随后,我们看下在probe方法中调用的几个函数。首先是s3c2410fb_map_video_memory。
- /*
- * s3c2410fb_map_video_memory():
- * Allocates the DRAM memory for the frame buffer. This buffer is
- * remapped into a non-cached, non-buffered, memory region to
- * allow palette and pixel writes to occur without flushing the
- * cache. Once this area is remapped, all virtual memory
- * access to the video memory should occur at the new region.
- */
- static int __init s3c2410fb_map_video_memory(struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par;
- dma_addr_t map_dma;
- unsigned map_size = PAGE_ALIGN(info->fix.smem_len);
- dprintk("map_video_memory(fbi=%p) map_size %u\n", fbi, map_size);
- /*分配DMA缓冲区,并保存DMA缓冲区虚拟地址*/
- info->screen_base = dma_alloc_writecombine(fbi->dev, map_size,
- &map_dma, GFP_KERNEL);
- if (info->screen_base) {
- /* prevent initial garbage on screen */
- dprintk("map_video_memory: clear %p:%08x\n",
- info->screen_base, map_size);
- memset(info->screen_base, 0x00, map_size); /*DMA缓冲区清0*/
- info->fix.smem_start = map_dma; /*保存DMA缓冲区物理地址*/
- dprintk("map_video_memory: dma=%08lx cpu=%p size=%08x\n",
- info->fix.smem_start, info->screen_base, map_size);
- }
- return info->screen_base ? 0 : -ENOMEM;
- }
- /*
- * s3c2410fb_map_video_memory():
- * Allocates the DRAM memory for the frame buffer. This buffer is
- * remapped into a non-cached, non-buffered, memory region to
- * allow palette and pixel writes to occur without flushing the
- * cache. Once this area is remapped, all virtual memory
- * access to the video memory should occur at the new region.
- */
- static int __init s3c2410fb_map_video_memory(struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par;
- dma_addr_t map_dma;
- unsigned map_size = PAGE_ALIGN(info->fix.smem_len);
- dprintk("map_video_memory(fbi=%p) map_size %u\n", fbi, map_size);
- /*分配DMA缓冲区,并保存DMA缓冲区虚拟地址*/
- info->screen_base = dma_alloc_writecombine(fbi->dev, map_size,
- &map_dma, GFP_KERNEL);
- if (info->screen_base) {
- /* prevent initial garbage on screen */
- dprintk("map_video_memory: clear %p:%08x\n",
- info->screen_base, map_size);
- memset(info->screen_base, 0x00, map_size); /*DMA缓冲区清0*/
- info->fix.smem_start = map_dma; /*保存DMA缓冲区物理地址*/
- dprintk("map_video_memory: dma=%08lx cpu=%p size=%08x\n",
- info->fix.smem_start, info->screen_base, map_size);
- }
- return info->screen_base ? 0 : -ENOMEM;
- }
该函数根据fix.smem_len的大小,分配了一个DMA缓冲区,保存了该缓冲区的物理地址和虚拟地址。
接着是s3c2410fb_init_registers:
- /*
- * s3c2410fb_init_registers - Initialise all LCD-related registers
- */
- static int s3c2410fb_init_registers(struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par; /*par指向s3c2410fb_info*/
- struct s3c2410fb_mach_info *mach_info = fbi->dev->platform_data;
- unsigned long flags;
- void __iomem *regs = fbi->io;
- void __iomem *tpal;
- void __iomem *lpcsel;
- if (is_s3c2412(fbi)) {
- tpal = regs + S3C2412_TPAL;
- lpcsel = regs + S3C2412_TCONSEL;
- } else {
- tpal = regs + S3C2410_TPAL;
- lpcsel = regs + S3C2410_LPCSEL;
- }
- /* Initialise LCD with values from haret */
- local_irq_save(flags); /*禁止所有中断*/
- /* modify the gpio(s) with interrupts set (bjd) */ /*初始化io管脚*/
- modify_gpio(S3C2410_GPCUP, mach_info->gpcup, mach_info->gpcup_mask);
- modify_gpio(S3C2410_GPCCON, mach_info->gpccon, mach_info->gpccon_mask);
- modify_gpio(S3C2410_GPDUP, mach_info->gpdup, mach_info->gpdup_mask);
- modify_gpio(S3C2410_GPDCON, mach_info->gpdcon, mach_info->gpdcon_mask);
- local_irq_restore(flags); /*恢复中断*/
- dprintk("LPCSEL = 0x%08lx\n", mach_info->lpcsel); /*设置TCONSEL,禁止LPC3600*/
- writel(mach_info->lpcsel, lpcsel);
- dprintk("replacing TPAL %08x\n", readl(tpal));
- /* ensure temporary palette disabled */
- writel(0x00, tpal); /*禁止调色板*/
- return 0;
- }
- static inline void modify_gpio(void __iomem *reg,
- unsigned long set, unsigned long mask)
- {
- unsigned long tmp;
- tmp = readl(reg) & ~mask;
- writel(tmp | set, reg);
- }
- /*
- * s3c2410fb_init_registers - Initialise all LCD-related registers
- */
- static int s3c2410fb_init_registers(struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par; /*par指向s3c2410fb_info*/
- struct s3c2410fb_mach_info *mach_info = fbi->dev->platform_data;
- unsigned long flags;
- void __iomem *regs = fbi->io;
- void __iomem *tpal;
- void __iomem *lpcsel;
- if (is_s3c2412(fbi)) {
- tpal = regs + S3C2412_TPAL;
- lpcsel = regs + S3C2412_TCONSEL;
- } else {
- tpal = regs + S3C2410_TPAL;
- lpcsel = regs + S3C2410_LPCSEL;
- }
- /* Initialise LCD with values from haret */
- local_irq_save(flags); /*禁止所有中断*/
- /* modify the gpio(s) with interrupts set (bjd) */ /*初始化io管脚*/
- modify_gpio(S3C2410_GPCUP, mach_info->gpcup, mach_info->gpcup_mask);
- modify_gpio(S3C2410_GPCCON, mach_info->gpccon, mach_info->gpccon_mask);
- modify_gpio(S3C2410_GPDUP, mach_info->gpdup, mach_info->gpdup_mask);
- modify_gpio(S3C2410_GPDCON, mach_info->gpdcon, mach_info->gpdcon_mask);
- local_irq_restore(flags); /*恢复中断*/
- dprintk("LPCSEL = 0x%08lx\n", mach_info->lpcsel); /*设置TCONSEL,禁止LPC3600*/
- writel(mach_info->lpcsel, lpcsel);
- dprintk("replacing TPAL %08x\n", readl(tpal));
- /* ensure temporary palette disabled */
- writel(0x00, tpal); /*禁止调色板*/
- return 0;
- }
- static inline void modify_gpio(void __iomem *reg,
- unsigned long set, unsigned long mask)
- {
- unsigned long tmp;
- tmp = readl(reg) & ~mask;
- writel(tmp | set, reg);
- }
最后是s3c2410fb_check_var:
- /*
- * s3c2410fb_check_var():
- * Get the video params out of ‘var‘. If a value doesn‘t fit, round it up,
- * if it‘s too big, return -EINVAL.
- * 检查变量的合法性
- */
- static int s3c2410fb_check_var(struct fb_var_screeninfo *var,
- struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par; /*par指向s3c2410fb_info*/
- struct s3c2410fb_mach_info *mach_info = fbi->dev->platform_data;/*指向s3c2410fb_mach_info*/
- struct s3c2410fb_display *display = NULL;
- struct s3c2410fb_display *default_display = mach_info->displays +
- mach_info->default_display;
- int type = default_display->type; /*S3C2410_LCDCON1_TFT*/
- unsigned i;
- dprintk("check_var(var=%p, info=%p)\n", var, info);
- /* validate x/y resolution */
- /* choose default mode if possible */ /*var中的成员在probe中设置*/
- if (var->yres == default_display->yres &&
- var->xres == default_display->xres &&
- var->bits_per_pixel == default_display->bpp)
- display = default_display;
- else
- for (i = 0; i < mach_info->num_displays; i++)
- if (type == mach_info->displays[i].type &&
- var->yres == mach_info->displays[i].yres &&
- var->xres == mach_info->displays[i].xres &&
- var->bits_per_pixel == mach_info->displays[i].bpp) {
- display = mach_info->displays + i;
- break;
- }
- if (!display) {
- dprintk("wrong resolution or depth %dx%d at %d bpp\n",
- var->xres, var->yres, var->bits_per_pixel);
- return -EINVAL;
- }
- /* it is always the size as the display */
- var->xres_virtual = display->xres;
- var->yres_virtual = display->yres;
- var->height = display->height;
- var->width = display->width;
- /* copy lcd settings */
- var->pixclock = display->pixclock;
- var->left_margin = display->left_margin;
- var->right_margin = display->right_margin;
- var->upper_margin = display->upper_margin;
- var->lower_margin = display->lower_margin;
- var->vsync_len = display->vsync_len;
- var->hsync_len = display->hsync_len;
- fbi->regs.lcdcon5 = display->lcdcon5;
- /* set display type */
- fbi->regs.lcdcon1 = display->type;
- var->transp.offset = 0;
- var->transp.length = 0;
- /* set r/g/b positions */
- switch (var->bits_per_pixel) {
- case 1:
- case 2:
- case 4:
- var->red.offset = 0;
- var->red.length = var->bits_per_pixel;
- var->green = var->red;
- var->blue = var->red;
- break;
- case 8:
- if (display->type != S3C2410_LCDCON1_TFT) {
- /* 8 bpp 332 */
- var->red.length = 3;
- var->red.offset = 5;
- var->green.length = 3;
- var->green.offset = 2;
- var->blue.length = 2;
- var->blue.offset = 0;
- } else {
- var->red.offset = 0;
- var->red.length = 8;
- var->green = var->red;
- var->blue = var->red;
- }
- break;
- case 12:
- /* 12 bpp 444 */
- var->red.length = 4;
- var->red.offset = 8;
- var->green.length = 4;
- var->green.offset = 4;
- var->blue.length = 4;
- var->blue.offset = 0;
- break;
- default:
- case 16:
- if (display->lcdcon5 & S3C2410_LCDCON5_FRM565) { /*使用565格式*/
- /* 16 bpp, 565 format */
- var->red.offset = 11;
- var->green.offset = 5;
- var->blue.offset = 0;
- var->red.length = 5;
- var->green.length = 6;
- var->blue.length = 5;
- } else {
- /* 16 bpp, 5551 format */
- var->red.offset = 11;
- var->green.offset = 6;
- var->blue.offset = 1;
- var->red.length = 5;
- var->green.length = 5;
- var->blue.length = 5;
- }
- break;
- case 32:
- /* 24 bpp 888 and 8 dummy */
- var->red.length = 8;
- var->red.offset = 16;
- var->green.length = 8;
- var->green.offset = 8;
- var->blue.length = 8;
- var->blue.offset = 0;
- break;
- }
- return 0;
- }
- /* Interpretation of offset for color fields: All offsets are from the right,
- * inside a "pixel" value, which is exactly ‘bits_per_pixel‘ wide (means: you
- * can use the offset as right argument to <<). A pixel afterwards is a bit
- * stream and is written to video memory as that unmodified.
- *
- * For pseudocolor: offset and length should be the same for all color
- * components. Offset specifies the position of the least significant bit
- * of the pallette index in a pixel value. Length indicates the number
- * of available palette entries (i.e. # of entries = 1 << length).
- */
- struct fb_bitfield {
- __u32 offset; /* beginning of bitfield */
- __u32 length; /* length of bitfield */
- __u32 msb_right; /* != 0 : Most significant bit is */
- /* right */
- };
- /*
- * s3c2410fb_check_var():
- * Get the video params out of ‘var‘. If a value doesn‘t fit, round it up,
- * if it‘s too big, return -EINVAL.
- * 检查变量的合法性
- */
- static int s3c2410fb_check_var(struct fb_var_screeninfo *var,
- struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par; /*par指向s3c2410fb_info*/
- struct s3c2410fb_mach_info *mach_info = fbi->dev->platform_data;/*指向s3c2410fb_mach_info*/
- struct s3c2410fb_display *display = NULL;
- struct s3c2410fb_display *default_display = mach_info->displays +
- mach_info->default_display;
- int type = default_display->type; /*S3C2410_LCDCON1_TFT*/
- unsigned i;
- dprintk("check_var(var=%p, info=%p)\n", var, info);
- /* validate x/y resolution */
- /* choose default mode if possible */ /*var中的成员在probe中设置*/
- if (var->yres == default_display->yres &&
- var->xres == default_display->xres &&
- var->bits_per_pixel == default_display->bpp)
- display = default_display;
- else
- for (i = 0; i < mach_info->num_displays; i++)
- if (type == mach_info->displays[i].type &&
- var->yres == mach_info->displays[i].yres &&
- var->xres == mach_info->displays[i].xres &&
- var->bits_per_pixel == mach_info->displays[i].bpp) {
- display = mach_info->displays + i;
- break;
- }
- if (!display) {
- dprintk("wrong resolution or depth %dx%d at %d bpp\n",
- var->xres, var->yres, var->bits_per_pixel);
- return -EINVAL;
- }
- /* it is always the size as the display */
- var->xres_virtual = display->xres;
- var->yres_virtual = display->yres;
- var->height = display->height;
- var->width = display->width;
- /* copy lcd settings */
- var->pixclock = display->pixclock;
- var->left_margin = display->left_margin;
- var->right_margin = display->right_margin;
- var->upper_margin = display->upper_margin;
- var->lower_margin = display->lower_margin;
- var->vsync_len = display->vsync_len;
- var->hsync_len = display->hsync_len;
- fbi->regs.lcdcon5 = display->lcdcon5;
- /* set display type */
- fbi->regs.lcdcon1 = display->type;
- var->transp.offset = 0;
- var->transp.length = 0;
- /* set r/g/b positions */
- switch (var->bits_per_pixel) {
- case 1:
- case 2:
- case 4:
- var->red.offset = 0;
- var->red.length = var->bits_per_pixel;
- var->green = var->red;
- var->blue = var->red;
- break;
- case 8:
- if (display->type != S3C2410_LCDCON1_TFT) {
- /* 8 bpp 332 */
- var->red.length = 3;
- var->red.offset = 5;
- var->green.length = 3;
- var->green.offset = 2;
- var->blue.length = 2;
- var->blue.offset = 0;
- } else {
- var->red.offset = 0;
- var->red.length = 8;
- var->green = var->red;
- var->blue = var->red;
- }
- break;
- case 12:
- /* 12 bpp 444 */
- var->red.length = 4;
- var->red.offset = 8;
- var->green.length = 4;
- var->green.offset = 4;
- var->blue.length = 4;
- var->blue.offset = 0;
- break;
- default:
- case 16:
- if (display->lcdcon5 & S3C2410_LCDCON5_FRM565) { /*使用565格式*/
- /* 16 bpp, 565 format */
- var->red.offset = 11;
- var->green.offset = 5;
- var->blue.offset = 0;
- var->red.length = 5;
- var->green.length = 6;
- var->blue.length = 5;
- } else {
- /* 16 bpp, 5551 format */
- var->red.offset = 11;
- var->green.offset = 6;
- var->blue.offset = 1;
- var->red.length = 5;
- var->green.length = 5;
- var->blue.length = 5;
- }
- break;
- case 32:
- /* 24 bpp 888 and 8 dummy */
- var->red.length = 8;
- var->red.offset = 16;
- var->green.length = 8;
- var->green.offset = 8;
- var->blue.length = 8;
- var->blue.offset = 0;
- break;
- }
- return 0;
- }
- /* Interpretation of offset for color fields: All offsets are from the right,
- * inside a "pixel" value, which is exactly ‘bits_per_pixel‘ wide (means: you
- * can use the offset as right argument to <<). A pixel afterwards is a bit
- * stream and is written to video memory as that unmodified.
- *
- * For pseudocolor: offset and length should be the same for all color
- * components. Offset specifies the position of the least significant bit
- * of the pallette index in a pixel value. Length indicates the number
- * of available palette entries (i.e. # of entries = 1 << length).
- */
- struct fb_bitfield {
- __u32 offset; /* beginning of bitfield */
- __u32 length; /* length of bitfield */
- __u32 msb_right; /* != 0 : Most significant bit is */
- /* right */
- };
该函数主要将板级信息s3c2410fb_display复制到对应的地方,然后根据RGB的模式设置位域。
4.3 fb_ops方法
在驱动程序中,定义了fb_ops,如下:
- static struct fb_ops s3c2410fb_ops = {
- .owner = THIS_MODULE,
- .fb_check_var = s3c2410fb_check_var, /*检查变量的合法性*/
- .fb_set_par = s3c2410fb_set_par, /*将参数写入LCD控制器,该函数由帧缓冲核心调用*/
- .fb_blank = s3c2410fb_blank, /*该方法支持显示消隐和去消隐*/
- .fb_setcolreg = s3c2410fb_setcolreg, /*设置颜色寄存器*/
- .fb_fillrect = cfb_fillrect, /*用像素行填充矩形框,通用库函数*/
- .fb_copyarea = cfb_copyarea, /*将屏幕的一个矩形区域复制到另一个区域,通用库函数*/
- .fb_imageblit = cfb_imageblit, /*显示一副图像,通用库函数*/
- };
- static struct fb_ops s3c2410fb_ops = {
- .owner = THIS_MODULE,
- .fb_check_var = s3c2410fb_check_var, /*检查变量的合法性*/
- .fb_set_par = s3c2410fb_set_par, /*将参数写入LCD控制器,该函数由帧缓冲核心调用*/
- .fb_blank = s3c2410fb_blank, /*该方法支持显示消隐和去消隐*/
- .fb_setcolreg = s3c2410fb_setcolreg, /*设置颜色寄存器*/
- .fb_fillrect = cfb_fillrect, /*用像素行填充矩形框,通用库函数*/
- .fb_copyarea = cfb_copyarea, /*将屏幕的一个矩形区域复制到另一个区域,通用库函数*/
- .fb_imageblit = cfb_imageblit, /*显示一副图像,通用库函数*/
- };
其中s3c2410fb_check_var在4.2节中已经分析过了,最后三个方法是通用库函数,在这里不作分析。
剩余三个也是驱动程序提供的,现在对这三个程序进行分析。
4.3. 1 s3c2410fb_set_par
- /*
- * s3c2410fb_set_par - Alters the hardware state.
- * @info: frame buffer structure that represents a single frame buffer
- * 根据var中的值设置LCD控制器的寄存器
- */
- static int s3c2410fb_set_par(struct fb_info *info)
- {
- struct fb_var_screeninfo *var = &info->var;
- switch (var->bits_per_pixel) {
- case 32:
- case 16:
- case 12:
- info->fix.visual = FB_VISUAL_TRUECOLOR;
- break;
- case 1:
- info->fix.visual = FB_VISUAL_MONO01;
- break;
- default:
- info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
- break;
- }
- info->fix.line_length = (var->xres_virtual * var->bits_per_pixel) / 8; /* 320*16/8 = 640Bytes */
- /* activate this new configuration */
- s3c2410fb_activate_var(info);
- return 0;
- }
- /*
- * s3c2410fb_set_par - Alters the hardware state.
- * @info: frame buffer structure that represents a single frame buffer
- * 根据var中的值设置LCD控制器的寄存器
- */
- static int s3c2410fb_set_par(struct fb_info *info)
- {
- struct fb_var_screeninfo *var = &info->var;
- switch (var->bits_per_pixel) {
- case 32:
- case 16:
- case 12:
- info->fix.visual = FB_VISUAL_TRUECOLOR;
- break;
- case 1:
- info->fix.visual = FB_VISUAL_MONO01;
- break;
- default:
- info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
- break;
- }
- info->fix.line_length = (var->xres_virtual * var->bits_per_pixel) / 8; /* 320*16/8 = 640Bytes */
- /* activate this new configuration */
- s3c2410fb_activate_var(info);
- return 0;
- }
该函数根据像素的位数设置了视觉模式,本例为16为,使用真彩色。然后计算了每行的数据元素大小。共240行。
然后调用了s3c2410fb_activate_var来设置控制器并激活LCD。
s3c2410fb_activate_var函数如下:
- /* s3c2410fb_activate_var
- *
- * activate (set) the controller from the given framebuffer
- * information
- */
- static void s3c2410fb_activate_var(struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par;
- void __iomem *regs = fbi->io;
- int type = fbi->regs.lcdcon1 & S3C2410_LCDCON1_TFT; /*regs.lcdcon1在s3c2410fb_check_var设置*/
- struct fb_var_screeninfo *var = &info->var;
- int clkdiv = s3c2410fb_calc_pixclk(fbi, var->pixclock) / 2;
- dprintk("%s: var->xres = %d\n", __func__, var->xres);
- dprintk("%s: var->yres = %d\n", __func__, var->yres);
- dprintk("%s: var->bpp = %d\n", __func__, var->bits_per_pixel);
- if (type == S3C2410_LCDCON1_TFT) {
- s3c2410fb_calculate_tft_lcd_regs(info, &fbi->regs);/*根据var,计算出控制寄存器需要设置的值*/
- --clkdiv;
- if (clkdiv < 0)
- clkdiv = 0;
- } else {
- s3c2410fb_calculate_stn_lcd_regs(info, &fbi->regs);
- if (clkdiv < 2)
- clkdiv = 2;
- }
- fbi->regs.lcdcon1 |= S3C2410_LCDCON1_CLKVAL(clkdiv);/*设置CLKVAL*/
- /* write new registers */
- dprintk("new register set:\n");
- dprintk("lcdcon[1] = 0x%08lx\n", fbi->regs.lcdcon1);
- dprintk("lcdcon[2] = 0x%08lx\n", fbi->regs.lcdcon2);
- dprintk("lcdcon[3] = 0x%08lx\n", fbi->regs.lcdcon3);
- dprintk("lcdcon[4] = 0x%08lx\n", fbi->regs.lcdcon4);
- dprintk("lcdcon[5] = 0x%08lx\n", fbi->regs.lcdcon5);
- /*把计算好的值填入LCD控制器中*/
- writel(fbi->regs.lcdcon1 & ~S3C2410_LCDCON1_ENVID,
- regs + S3C2410_LCDCON1); /*仍然禁止LCD*/
- writel(fbi->regs.lcdcon2, regs + S3C2410_LCDCON2);
- writel(fbi->regs.lcdcon3, regs + S3C2410_LCDCON3);
- writel(fbi->regs.lcdcon4, regs + S3C2410_LCDCON4);
- writel(fbi->regs.lcdcon5, regs + S3C2410_LCDCON5);
- /* set lcd address pointers */
- s3c2410fb_set_lcdaddr(info); /*设置LCD帧缓冲起始地址*/
- fbi->regs.lcdcon1 |= S3C2410_LCDCON1_ENVID,
- writel(fbi->regs.lcdcon1, regs + S3C2410_LCDCON1); /*使能LCD*/
- }
- /* s3c2410fb_activate_var
- *
- * activate (set) the controller from the given framebuffer
- * information
- */
- static void s3c2410fb_activate_var(struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par;
- void __iomem *regs = fbi->io;
- int type = fbi->regs.lcdcon1 & S3C2410_LCDCON1_TFT; /*regs.lcdcon1在s3c2410fb_check_var设置*/
- struct fb_var_screeninfo *var = &info->var;
- int clkdiv = s3c2410fb_calc_pixclk(fbi, var->pixclock) / 2;
- dprintk("%s: var->xres = %d\n", __func__, var->xres);
- dprintk("%s: var->yres = %d\n", __func__, var->yres);
- dprintk("%s: var->bpp = %d\n", __func__, var->bits_per_pixel);
- if (type == S3C2410_LCDCON1_TFT) {
- s3c2410fb_calculate_tft_lcd_regs(info, &fbi->regs);/*根据var,计算出控制寄存器需要设置的值*/
- --clkdiv;
- if (clkdiv < 0)
- clkdiv = 0;
- } else {
- s3c2410fb_calculate_stn_lcd_regs(info, &fbi->regs);
- if (clkdiv < 2)
- clkdiv = 2;
- }
- fbi->regs.lcdcon1 |= S3C2410_LCDCON1_CLKVAL(clkdiv);/*设置CLKVAL*/
- /* write new registers */
- dprintk("new register set:\n");
- dprintk("lcdcon[1] = 0x%08lx\n", fbi->regs.lcdcon1);
- dprintk("lcdcon[2] = 0x%08lx\n", fbi->regs.lcdcon2);
- dprintk("lcdcon[3] = 0x%08lx\n", fbi->regs.lcdcon3);
- dprintk("lcdcon[4] = 0x%08lx\n", fbi->regs.lcdcon4);
- dprintk("lcdcon[5] = 0x%08lx\n", fbi->regs.lcdcon5);
- /*把计算好的值填入LCD控制器中*/
- writel(fbi->regs.lcdcon1 & ~S3C2410_LCDCON1_ENVID,
- regs + S3C2410_LCDCON1); /*仍然禁止LCD*/
- writel(fbi->regs.lcdcon2, regs + S3C2410_LCDCON2);
- writel(fbi->regs.lcdcon3, regs + S3C2410_LCDCON3);
- writel(fbi->regs.lcdcon4, regs + S3C2410_LCDCON4);
- writel(fbi->regs.lcdcon5, regs + S3C2410_LCDCON5);
- /* set lcd address pointers */
- s3c2410fb_set_lcdaddr(info); /*设置LCD帧缓冲起始地址*/
- fbi->regs.lcdcon1 |= S3C2410_LCDCON1_ENVID,
- writel(fbi->regs.lcdcon1, regs + S3C2410_LCDCON1); /*使能LCD*/
- }
其中调用的三个函数如下:
- static unsigned int s3c2410fb_calc_pixclk(struct s3c2410fb_info *fbi,
- unsigned long pixclk)
- {
- unsigned long clk = clk_get_rate(fbi->clk); /*获取当前时钟频率(Hz)*/
- unsigned long long div;
- /* pixclk is in picoseconds, our clock is in Hz
- *
- * Hz -> picoseconds is / 10^-12
- */
- div = (unsigned long long)clk * pixclk;
- div >>= 12; /* div / 2^12 */
- do_div(div, 625 * 625UL * 625); /* div / 5^12 */
- dprintk("pixclk %ld, divisor is %ld\n", pixclk, (long)div);
- return div;
- }
- /* s3c2410fb_calculate_tft_lcd_regs
- *
- * calculate register values from var settings
- */
- static void s3c2410fb_calculate_tft_lcd_regs(const struct fb_info *info,
- struct s3c2410fb_hw *regs)
- {
- const struct s3c2410fb_info *fbi = info->par;
- const struct fb_var_screeninfo *var = &info->var;
- switch (var->bits_per_pixel) {
- case 1:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT1BPP;
- break;
- case 2:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT2BPP;
- break;
- case 4:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT4BPP;
- break;
- case 8:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT8BPP;
- regs->lcdcon5 |= S3C2410_LCDCON5_BSWP |
- S3C2410_LCDCON5_FRM565;
- regs->lcdcon5 &= ~S3C2410_LCDCON5_HWSWP;
- break;
- case 16:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT16BPP;
- regs->lcdcon5 &= ~S3C2410_LCDCON5_BSWP;
- regs->lcdcon5 |= S3C2410_LCDCON5_HWSWP;
- break;
- case 32:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT24BPP;
- regs->lcdcon5 &= ~(S3C2410_LCDCON5_BSWP |
- S3C2410_LCDCON5_HWSWP |
- S3C2410_LCDCON5_BPP24BL);
- break;
- default:
- /* invalid pixel depth */
- dev_err(fbi->dev, "invalid bpp %d\n",
- var->bits_per_pixel);
- }
- /* update X/Y info */
- dprintk("setting vert: up=%d, low=%d, sync=%d\n",
- var->upper_margin, var->lower_margin, var->vsync_len);
- dprintk("setting horz: lft=%d, rt=%d, sync=%d\n",
- var->left_margin, var->right_margin, var->hsync_len);
- /*
- 所有时序参数必须减1,因为在公式中:
- Frame Rate = 1/ [ { (VSPW+1) + (VBPD+1) + (LIINEVAL + 1) + (VFPD+1) } x {(HSPW+1) + (HBPD +1)
- + (HFPD+1) + (HOZVAL + 1) } x { 2 x ( CLKVAL+1 ) / ( HCLK ) } ]
- */
- regs->lcdcon2 = S3C2410_LCDCON2_LINEVAL(var->yres - 1) |
- S3C2410_LCDCON2_VBPD(var->upper_margin - 1) |
- S3C2410_LCDCON2_VFPD(var->lower_margin - 1) |
- S3C2410_LCDCON2_VSPW(var->vsync_len - 1);
- regs->lcdcon3 = S3C2410_LCDCON3_HBPD(var->right_margin - 1) |
- S3C2410_LCDCON3_HFPD(var->left_margin - 1) |
- S3C2410_LCDCON3_HOZVAL(var->xres - 1);
- regs->lcdcon4 = S3C2410_LCDCON4_HSPW(var->hsync_len - 1);
- }
- /* s3c2410fb_set_lcdaddr
- *
- * initialise lcd controller address pointers
- */
- static void s3c2410fb_set_lcdaddr(struct fb_info *info)
- {
- unsigned long saddr1, saddr2, saddr3;
- struct s3c2410fb_info *fbi = info->par;
- void __iomem *regs = fbi->io;
- saddr1 = info->fix.smem_start >> 1; /*帧缓冲区起始地址*/
- saddr2 = info->fix.smem_start;
- saddr2 += info->fix.line_length * info->var.yres;
- saddr2 >>= 1; /*帧缓冲区结束地址*/
- saddr3 = S3C2410_OFFSIZE(0) |
- S3C2410_PAGEWIDTH((info->fix.line_length / 2) & 0x3ff); /*offset = 0, pagewidth = 320*/
- dprintk("LCDSADDR1 = 0x%08lx\n", saddr1);
- dprintk("LCDSADDR2 = 0x%08lx\n", saddr2);
- dprintk("LCDSADDR3 = 0x%08lx\n", saddr3);
- writel(saddr1, regs + S3C2410_LCDSADDR1);
- writel(saddr2, regs + S3C2410_LCDSADDR2);
- writel(saddr3, regs + S3C2410_LCDSADDR3);
- }
- static unsigned int s3c2410fb_calc_pixclk(struct s3c2410fb_info *fbi,
- unsigned long pixclk)
- {
- unsigned long clk = clk_get_rate(fbi->clk); /*获取当前时钟频率(Hz)*/
- unsigned long long div;
- /* pixclk is in picoseconds, our clock is in Hz
- *
- * Hz -> picoseconds is / 10^-12
- */
- div = (unsigned long long)clk * pixclk;
- div >>= 12; /* div / 2^12 */
- do_div(div, 625 * 625UL * 625); /* div / 5^12 */
- dprintk("pixclk %ld, divisor is %ld\n", pixclk, (long)div);
- return div;
- }
- /* s3c2410fb_calculate_tft_lcd_regs
- *
- * calculate register values from var settings
- */
- static void s3c2410fb_calculate_tft_lcd_regs(const struct fb_info *info,
- struct s3c2410fb_hw *regs)
- {
- const struct s3c2410fb_info *fbi = info->par;
- const struct fb_var_screeninfo *var = &info->var;
- switch (var->bits_per_pixel) {
- case 1:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT1BPP;
- break;
- case 2:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT2BPP;
- break;
- case 4:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT4BPP;
- break;
- case 8:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT8BPP;
- regs->lcdcon5 |= S3C2410_LCDCON5_BSWP |
- S3C2410_LCDCON5_FRM565;
- regs->lcdcon5 &= ~S3C2410_LCDCON5_HWSWP;
- break;
- case 16:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT16BPP;
- regs->lcdcon5 &= ~S3C2410_LCDCON5_BSWP;
- regs->lcdcon5 |= S3C2410_LCDCON5_HWSWP;
- break;
- case 32:
- regs->lcdcon1 |= S3C2410_LCDCON1_TFT24BPP;
- regs->lcdcon5 &= ~(S3C2410_LCDCON5_BSWP |
- S3C2410_LCDCON5_HWSWP |
- S3C2410_LCDCON5_BPP24BL);
- break;
- default:
- /* invalid pixel depth */
- dev_err(fbi->dev, "invalid bpp %d\n",
- var->bits_per_pixel);
- }
- /* update X/Y info */
- dprintk("setting vert: up=%d, low=%d, sync=%d\n",
- var->upper_margin, var->lower_margin, var->vsync_len);
- dprintk("setting horz: lft=%d, rt=%d, sync=%d\n",
- var->left_margin, var->right_margin, var->hsync_len);
- /*
- 所有时序参数必须减1,因为在公式中:
- Frame Rate = 1/ [ { (VSPW+1) + (VBPD+1) + (LIINEVAL + 1) + (VFPD+1) } x {(HSPW+1) + (HBPD +1)
- + (HFPD+1) + (HOZVAL + 1) } x { 2 x ( CLKVAL+1 ) / ( HCLK ) } ]
- */
- regs->lcdcon2 = S3C2410_LCDCON2_LINEVAL(var->yres - 1) |
- S3C2410_LCDCON2_VBPD(var->upper_margin - 1) |
- S3C2410_LCDCON2_VFPD(var->lower_margin - 1) |
- S3C2410_LCDCON2_VSPW(var->vsync_len - 1);
- regs->lcdcon3 = S3C2410_LCDCON3_HBPD(var->right_margin - 1) |
- S3C2410_LCDCON3_HFPD(var->left_margin - 1) |
- S3C2410_LCDCON3_HOZVAL(var->xres - 1);
- regs->lcdcon4 = S3C2410_LCDCON4_HSPW(var->hsync_len - 1);
- }
- /* s3c2410fb_set_lcdaddr
- *
- * initialise lcd controller address pointers
- */
- static void s3c2410fb_set_lcdaddr(struct fb_info *info)
- {
- unsigned long saddr1, saddr2, saddr3;
- struct s3c2410fb_info *fbi = info->par;
- void __iomem *regs = fbi->io;
- saddr1 = info->fix.smem_start >> 1; /*帧缓冲区起始地址*/
- saddr2 = info->fix.smem_start;
- saddr2 += info->fix.line_length * info->var.yres;
- saddr2 >>= 1; /*帧缓冲区结束地址*/
- saddr3 = S3C2410_OFFSIZE(0) |
- S3C2410_PAGEWIDTH((info->fix.line_length / 2) & 0x3ff); /*offset = 0, pagewidth = 320*/
- dprintk("LCDSADDR1 = 0x%08lx\n", saddr1);
- dprintk("LCDSADDR2 = 0x%08lx\n", saddr2);
- dprintk("LCDSADDR3 = 0x%08lx\n", saddr3);
- writel(saddr1, regs + S3C2410_LCDSADDR1);
- writel(saddr2, regs + S3C2410_LCDSADDR2);
- writel(saddr3, regs + S3C2410_LCDSADDR3);
- }
s3c2410fb_calc_pixclk用于计算时钟频率。
s3c2410fb_calculate_tft_lcd_regs设置了LCD的控制寄存器。
s3c2410fb_set_lcdaddr设置了LCD的地址寄存器,该寄存器的设置请参考datasheet。
4.3. 2 s3c2410fb_blank
该方法完成消隐功能。
- /*
- * s3c2410fb_blank
- * @blank_mode: the blank mode we want.
- * @info: frame buffer structure that represents a single frame buffer
- *
- * Blank the screen if blank_mode != 0, else unblank. Return 0 if
- * blanking succeeded, != 0 if un-/blanking failed due to e.g. a
- * video mode which doesn‘t support it. Implements VESA suspend
- * and powerdown modes on hardware that supports disabling hsync/vsync:
- *
- * Returns negative errno on error, or zero on success.
- *
- */
- static int s3c2410fb_blank(int blank_mode, struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par;
- void __iomem *tpal_reg = fbi->io;
- dprintk("blank(mode=%d, info=%p)\n", blank_mode, info);
- tpal_reg += is_s3c2412(fbi) ? S3C2412_TPAL : S3C2410_TPAL;
- if (blank_mode == FB_BLANK_POWERDOWN) { /*消隐*/
- s3c2410fb_lcd_enable(fbi, 0); /*禁止LCD*/
- } else {
- s3c2410fb_lcd_enable(fbi, 1); /*启动LCD*/
- }
- if (blank_mode == FB_BLANK_UNBLANK) /*去消隐*/
- writel(0x0, tpal_reg); /*禁止temporary palette*/
- else { /*消隐*/
- dprintk("setting TPAL to output 0x000000\n");
- writel(S3C2410_TPAL_EN, tpal_reg); /*使能temporary palette,颜色为黑色*/
- }
- return 0;
- }
- /*
- * s3c2410fb_blank
- * @blank_mode: the blank mode we want.
- * @info: frame buffer structure that represents a single frame buffer
- *
- * Blank the screen if blank_mode != 0, else unblank. Return 0 if
- * blanking succeeded, != 0 if un-/blanking failed due to e.g. a
- * video mode which doesn‘t support it. Implements VESA suspend
- * and powerdown modes on hardware that supports disabling hsync/vsync:
- *
- * Returns negative errno on error, or zero on success.
- *
- */
- static int s3c2410fb_blank(int blank_mode, struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par;
- void __iomem *tpal_reg = fbi->io;
- dprintk("blank(mode=%d, info=%p)\n", blank_mode, info);
- tpal_reg += is_s3c2412(fbi) ? S3C2412_TPAL : S3C2410_TPAL;
- if (blank_mode == FB_BLANK_POWERDOWN) { /*消隐*/
- s3c2410fb_lcd_enable(fbi, 0); /*禁止LCD*/
- } else {
- s3c2410fb_lcd_enable(fbi, 1); /*启动LCD*/
- }
- if (blank_mode == FB_BLANK_UNBLANK) /*去消隐*/
- writel(0x0, tpal_reg); /*禁止temporary palette*/
- else { /*消隐*/
- dprintk("setting TPAL to output 0x000000\n");
- writel(S3C2410_TPAL_EN, tpal_reg); /*使能temporary palette,颜色为黑色*/
- }
- return 0;
- }
在消隐时,屏幕将全黑。
4.3.3 s3c2410fb_setcolreg
该函数的功能用于设置LCD的调色板。调色板的概念请看我的转帖:LCD调色板。
- static int s3c2410fb_setcolreg(unsigned regno,
- unsigned red, unsigned green, unsigned blue,
- unsigned transp, struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par; /*par指向s3c2410fb_info*/
- void __iomem *regs = fbi->io;
- unsigned int val;
- /* dprintk("setcol: regno=%d, rgb=%d,%d,%d\n",
- regno, red, green, blue); */
- switch (info->fix.visual) {
- case FB_VISUAL_TRUECOLOR: /*使用真彩色*/
- /* true-colour, use pseudo-palette */
- if (regno < 16) { /*16种颜色,为什么只用16种颜色???????????*/
- u32 *pal = info->pseudo_palette;
- val = chan_to_field(red, &info->var.red);
- val |= chan_to_field(green, &info->var.green);
- val |= chan_to_field(blue, &info->var.blue);
- pal[regno] = val; /*保存颜色值*/
- }
- break;
- case FB_VISUAL_PSEUDOCOLOR:
- if (regno < 256) {
- /* currently assume RGB 5-6-5 mode */
- val = (red >> 0) & 0xf800;
- val |= (green >> 5) & 0x07e0;
- val |= (blue >> 11) & 0x001f;
- writel(val, regs + S3C2410_TFTPAL(regno));
- schedule_palette_update(fbi, regno, val);
- }
- break;
- default:
- return 1; /* unknown type */
- }
- return 0;
- }
- /* from pxafb.c */
- static inline unsigned int chan_to_field(unsigned int chan,
- struct fb_bitfield *bf)
- {
- /*下面用到的length和offset在s3c2410fb_check_var函数中设置*/
- chan &= 0xffff; /*取低16位*/
- chan >>= 16 - bf->length; /*取第length为到16位为有效位*/
- return chan << bf->offset; /*移动到相应的位置。*/
- }
- static int s3c2410fb_setcolreg(unsigned regno,
- unsigned red, unsigned green, unsigned blue,
- unsigned transp, struct fb_info *info)
- {
- struct s3c2410fb_info *fbi = info->par; /*par指向s3c2410fb_info*/
- void __iomem *regs = fbi->io;
- unsigned int val;
- /* dprintk("setcol: regno=%d, rgb=%d,%d,%d\n",
- regno, red, green, blue); */
- switch (info->fix.visual) {
- case FB_VISUAL_TRUECOLOR: /*使用真彩色*/
- /* true-colour, use pseudo-palette */
- if (regno < 16) { /*16种颜色,为什么只用16种颜色???????????*/
- u32 *pal = info->pseudo_palette;
- val = chan_to_field(red, &info->var.red);
- val |= chan_to_field(green, &info->var.green);
- val |= chan_to_field(blue, &info->var.blue);
- pal[regno] = val; /*保存颜色值*/
- }
- break;
- case FB_VISUAL_PSEUDOCOLOR:
- if (regno < 256) {
- /* currently assume RGB 5-6-5 mode */
- val = (red >> 0) & 0xf800;
- val |= (green >> 5) & 0x07e0;
- val |= (blue >> 11) & 0x001f;
- writel(val, regs + S3C2410_TFTPAL(regno));
- schedule_palette_update(fbi, regno, val);
- }
- break;
- default:
- return 1; /* unknown type */
- }
- return 0;
- }
- /* from pxafb.c */
- static inline unsigned int chan_to_field(unsigned int chan,
- struct fb_bitfield *bf)
- {
- /*下面用到的length和offset在s3c2410fb_check_var函数中设置*/
- chan &= 0xffff; /*取低16位*/
- chan >>= 16 - bf->length; /*取第length为到16位为有效位*/
- return chan << bf->offset; /*移动到相应的位置。*/
- }
我们使用的是真彩色,可以设置16种颜色,颜色的位域值通过调用chan_to_field获得,然后保存了颜色的值。但是比较奇怪的是,这里并没有将值保存到0x4d000400为起始的内存中,不知为何。 反而倒是在伪彩色模式下, 使用了writel(val, regs + S3C2410_TFTPAL(regno))写到内存中,然后调用schedule_palette_update函数来更新palette表。我们来看下。
- static void schedule_palette_update(struct s3c2410fb_info *fbi,
- unsigned int regno, unsigned int val)
- {
- unsigned long flags;
- unsigned long irqen;
- void __iomem *irq_base = fbi->irq_base;
- local_irq_save(flags);
- fbi->palette_buffer[regno] = val;
- if (!fbi->palette_ready) {
- fbi->palette_ready = 1;
- /* enable IRQ */
- irqen = readl(irq_base + S3C24XX_LCDINTMSK);
- irqen &= ~S3C2410_LCDINT_FRSYNC;
- writel(irqen, irq_base + S3C24XX_LCDINTMSK);
- }
- local_irq_restore(flags);
- }
- static void schedule_palette_update(struct s3c2410fb_info *fbi,
- unsigned int regno, unsigned int val)
- {
- unsigned long flags;
- unsigned long irqen;
- void __iomem *irq_base = fbi->irq_base;
- local_irq_save(flags);
- fbi->palette_buffer[regno] = val;
- if (!fbi->palette_ready) {
- fbi->palette_ready = 1;
- /* enable IRQ */
- irqen = readl(irq_base + S3C24XX_LCDINTMSK);
- irqen &= ~S3C2410_LCDINT_FRSYNC;
- writel(irqen, irq_base + S3C24XX_LCDINTMSK);
- }
- local_irq_restore(flags);
- }
这个函数的作用就是开启了LCD的帧同步中断,这个中断在VSYNC信号从无效变成有效时产生。当中断产生时,会调用在probe方法中注册的ISR。ISR如下:
- static irqreturn_t s3c2410fb_irq(int irq, void *dev_id)
- {
- struct s3c2410fb_info *fbi = dev_id;
- void __iomem *irq_base = fbi->irq_base;
- unsigned long lcdirq = readl(irq_base + S3C24XX_LCDINTPND);
- b
- if (lcdirq & S3C2410_LCDINT_FRSYNC) {
- if (fbi->palette_ready)
- s3c2410fb_write_palette(fbi);
- writel(S3C2410_LCDINT_FRSYNC, irq_base + S3C24XX_LCDINTPND);
- writel(S3C2410_LCDINT_FRSYNC, irq_base + S3C24XX_LCDSRCPND);
- }
- return IRQ_HANDLED;
- }
- static void s3c2410fb_write_palette(struct s3c2410fb_info *fbi)
- {
- unsigned int i;
- void __iomem *regs = fbi->io;
- fbi->palette_ready = 0; /*清除ready标志*/
- for (i = 0; i < 256; i++) {
- unsigned long ent = fbi->palette_buffer[i];
- if (ent == PALETTE_BUFF_CLEAR)
- continue;
- writel(ent, regs + S3C2410_TFTPAL(i));
- /* it seems the only way to know exactly
- * if the palette wrote ok, is to check
- * to see if the value verifies ok
- */
- if (readw(regs + S3C2410_TFTPAL(i)) == ent)
- fbi->palette_buffer[i] = PALETTE_BUFF_CLEAR;
- else
- fbi->palette_ready = 1; /* retry */
- }
- }
- static irqreturn_t s3c2410fb_irq(int irq, void *dev_id)
- {
- struct s3c2410fb_info *fbi = dev_id;
- void __iomem *irq_base = fbi->irq_base;
- unsigned long lcdirq = readl(irq_base + S3C24XX_LCDINTPND);
- b
- if (lcdirq & S3C2410_LCDINT_FRSYNC) {
- if (fbi->palette_ready)
- s3c2410fb_write_palette(fbi);
- writel(S3C2410_LCDINT_FRSYNC, irq_base + S3C24XX_LCDINTPND);
- writel(S3C2410_LCDINT_FRSYNC, irq_base + S3C24XX_LCDSRCPND);
- }
- return IRQ_HANDLED;
- }
- static void s3c2410fb_write_palette(struct s3c2410fb_info *fbi)
- {
- unsigned int i;
- void __iomem *regs = fbi->io;
- fbi->palette_ready = 0; /*清除ready标志*/
- for (i = 0; i < 256; i++) {
- unsigned long ent = fbi->palette_buffer[i];
- if (ent == PALETTE_BUFF_CLEAR)
- continue;
- writel(ent, regs + S3C2410_TFTPAL(i));
- /* it seems the only way to know exactly
- * if the palette wrote ok, is to check
- * to see if the value verifies ok
- */
- if (readw(regs + S3C2410_TFTPAL(i)) == ent)
- fbi->palette_buffer[i] = PALETTE_BUFF_CLEAR;
- else
- fbi->palette_ready = 1; /* retry */
- }
- }
在中断函数中调用了s3c2410fb_write_palette,该函数对写入内存的颜色值进行检查。如果确认其已经写入,则将palette_buffer中的清除,否则retry。
5. 总结
本文对frambuffer子系统做了简单的介绍。frambuffer子系统的函数相当之多,在这里是不可能一一介绍的。本文首先介绍了主要的数据结构,
随后分析了frambuffer核心层,在核心层简单的分析了5个API函数,接着,对驱动层做了介绍,驱动层的大多数函数都给出了分析。
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