九编写led驱动

Posted 2021-02-05 suzkfly

led.c

 1 #include <linux/init.h>
 2 #include <linux/module.h>
 3 #include <linux/cdev.h>
 4 #include <linux/fs.h>
 5 #include <linux/io.h>
 6 
 7 #define GPMCON    0x7F008820
 8 #define GPMDAT    0x7F008824
 9 
10 static int * __gp_gpmdat;
11 
12 static int led_open (struct inode *p_inode, struct file *p_file)
13 {
14     int *p_gpmcon = NULL;
15 
16     p_gpmcon = ioremap(GPMCON, 4);
17     writel(0x1111, p_gpmcon);
18 
19     __gp_gpmdat = ioremap(GPMDAT, 4);
20 
21     return 0;
22 }
23 
24 static long led_ioctl (struct file *p_file, unsigned int cmd, unsigned long arg)
25 {
26     switch (cmd) {
27     case 0:
28         writel(0x0, __gp_gpmdat);
29         break;
30     
31     case 1:
32         writel(0xF, __gp_gpmdat);
33         break;
34 
35     default:
36         return -1;
37     }
38     return 0;
39 }
40 
41 static struct cdev led_dev;
42 static struct file_operations fops = {
43     .open = led_open,
44     .unlocked_ioctl = led_ioctl,
45 };
46 dev_t devno;
47 
48 static __init int led_init (void)
49 {
50     cdev_init(&led_dev, &fops);
51     alloc_chrdev_region(&devno, 0, 1, "myled");
52     cdev_add(&led_dev, devno, 1);
53 
54     return 0;
55 }
56 
57 static __exit void led_exit (void)
58 {
59     cdev_del(&led_dev);
60     unregister_chrdev_region(devno, 1);
61 }
62 
63 module_init(led_init);
64 module_exit(led_exit);
65 
66 MODULE_LICENSE("GPL");

led_app.c

 1 #include <unistd.h>
 2 #include <sys/ioctl.h>
 3 #include <stdio.h>
 4 #include <sys/types.h>
 5 #include <sys/stat.h>
 6 #include <fcntl.h>
 7 
 8 int main(int argc, const char *argv[])
 9 {
10     int fd, cmd;
11 
12     if (argc != 2) {
13         printf(".example: ./led_app 0
");
14         return;
15     }
16 
17     cmd = atoi(argv[1]);
18 
19     fd = open("/dev/myled", O_RDWR);
20 
21     ioctl(fd, cmd);
22     
23     return 0;
24 }

Makefile

 1 obj-m := led.o
 2 KDIR = /home/linux/zkf/6410/urbetter-linux2.6.28-v1.0/
 3 
 4 all:
 5     make -C $(KDIR) $(objs) M=$(PWD) modules CROSS_COMPILE=arm-none-linux-gnueabi- ARCH=arm
 6     arm-none-linux-gnueabi-gcc led_app.c -o led_app
 7     sudo cp led.ko ~/zkf/6410/rootfs/home/test
 8     sudo cp led_app ~/zkf/6410/rootfs/home/test
 9 clean:
10     rm *.o *.symvers *.mod.c *.order

　　make之后会生成led.ko和led_app两个要用到的文件，在Makefile中已经将他们复制到了开发板挂载目录中。在开发板终端中输入命令：insmod led.ko 之后输入命令：cat /proc/devices 可以看到myled主设备号为251

　　输入命令：mknod /dev/myled c 251 0

　　之后便能执行应用程序led_app了，执行 ./led_app 0 则点亮所有LED，执行 ./led_app 1 则熄灭所有LED。