linux-2.6内核驱动学习——jz2440之按键

Posted 2021-02-03 Jason_linux

//以下是学习完韦东山老师视屏教程后所做学习记录


  1 #include <linux/module.h>
  2 #include <linux/kernel.h>
  3 #include <linux/fs.h>
  4 #include <linux/init.h>
  5 #include <linux/delay.h>
  6 #include <linux/irq.h>
  7 #include <asm/uaccess.h>
  8 #include <asm/irq.h>
  9 #include <asm/io.h>
 10 #include <asm/arch/regs-gpio.h>
 11 #include <asm/hardware.h>
 12 
 13 
 14 static struct class *thirddrv_class;
 15 static struct class_device    *thirddrv_class_dev;
 16 
 17 volatile unsigned long *gpfcon;
 18 volatile unsigned long *gpfdat;
 19 
 20 volatile unsigned long *gpgcon;
 21 volatile unsigned long *gpgdat;
 22 
 23 
 24 static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
 25 
 26 /* 中断事件标志, 中断服务程序将它置1，third_drv_read将它清0 */
 27 static volatile int ev_press = 0;
 28 
 29 
 30 struct pin_desc{
 31     unsigned int pin;
 32     unsigned int key_val;
 33 };
 34 
 35 
 36 /* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 */
 37 /* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */
 38 static unsigned char key_val;
 39 
 40 struct pin_desc pins_desc[4] = {
 41     {S3C2410_GPF0, 0x01},
 42     {S3C2410_GPF2, 0x02},
 43     {S3C2410_GPG3, 0x03},
 44     {S3C2410_GPG11, 0x04},
 45 };
 46 
 47 
 48 /*
 49   * 确定按键值
 50   */
 51 static irqreturn_t buttons_irq(int irq, void *dev_id)
 52 {
 53     struct pin_desc * pindesc = (struct pin_desc *)dev_id;
 54     unsigned int pinval;
 55     
 56     pinval = s3c2410_gpio_getpin(pindesc->pin);
 57 
 58     if (pinval)
 59     {
 60         /* 松开 */
 61         key_val = 0x80 | pindesc->key_val;
 62     }
 63     else
 64     {
 65         /* 按下 */
 66         key_val = pindesc->key_val;
 67     }
 68 
 69     ev_press = 1;                  /* 表示中断发生了 */
 70     wake_up_interruptible(&button_waitq);   /* 唤醒休眠的进程 */
 71 
 72     
 73     return IRQ_RETVAL(IRQ_HANDLED);
 74 }
 75 
 76 static int third_drv_open(struct inode *inode, struct file *file)
 77 {
 78     /* 配置GPF0,2为输入引脚 */
 79     /* 配置GPG3,11为输入引脚 */
 80     request_irq(IRQ_EINT0,  buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]);
 81     request_irq(IRQ_EINT2,  buttons_irq, IRQT_BOTHEDGE, "S3", &pins_desc[1]);
 82     request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "S4", &pins_desc[2]);
 83     request_irq(IRQ_EINT19, buttons_irq, IRQT_BOTHEDGE, "S5", &pins_desc[3]);    
 84 
 85     return 0;
 86 }
 87 
 88 ssize_t third_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 89 {
 90     if (size != 1)
 91         return -EINVAL;
 92 
 93     /* 如果没有按键动作, 休眠 */
 94     wait_event_interruptible(button_waitq, ev_press);
 95 
 96     /* 如果有按键动作, 返回键值 */
 97     copy_to_user(buf, &key_val, 1);
 98     ev_press = 0;
 99     
100     return 1;
101 }
102 
103 
104 int third_drv_close(struct inode *inode, struct file *file)
105 {
106     free_irq(IRQ_EINT0, &pins_desc[0]);
107     free_irq(IRQ_EINT2, &pins_desc[1]);
108     free_irq(IRQ_EINT11, &pins_desc[2]);
109     free_irq(IRQ_EINT19, &pins_desc[3]);
110     return 0;
111 }
112 
113 
114 static struct file_operations sencod_drv_fops = {
115     .owner   =  THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
116     .open    =  third_drv_open,     
117     .read     =    third_drv_read,       
118     .release =  third_drv_close,       
119 };
120 
121 
122 int major;
123 static int third_drv_init(void)
124 {
125     major = register_chrdev(0, "third_drv", &sencod_drv_fops);
126 
127     thirddrv_class = class_create(THIS_MODULE, "third_drv");
128 
129     thirddrv_class_dev = class_device_create(thirddrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */
130 
131     gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
132     gpfdat = gpfcon + 1;
133 
134     gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
135     gpgdat = gpgcon + 1;
136 
137     return 0;
138 }
139 
140 static void third_drv_exit(void)
141 {
142     unregister_chrdev(major, "third_drv");
143     class_device_unregister(thirddrv_class_dev);
144     class_destroy(thirddrv_class);
145     iounmap(gpfcon);
146     iounmap(gpgcon);
147     return 0;
148 }
149 
150 
151 module_init(third_drv_init);
152 
153 module_exit(third_drv_exit);
154 
155 MODULE_LICENSE("GPL");

测试用例

 1 #include <sys/types.h>
 2 #include <sys/stat.h>
 3 #include <fcntl.h>
 4 #include <stdio.h>
 5 
 6 /* thirddrvtest 
 7   */
 8 int main(int argc, char **argv)
 9 {
10     int fd;
11     unsigned char key_val;
12     
13     fd = open("/dev/buttons", O_RDWR);
14     if (fd < 0)
15     {
16         printf("can‘t open!
");
17     }
18 
19     while (1)
20     {
21         read(fd, &key_val, 1);
22         printf("key_val = 0x%x
", key_val);
23     }
24     
25     return 0;
26 }

以上是采用中断方式的写法。

下面学习了poll机制后，做了改进：