Linux驱动开发-OK6410-LED字符设备驱动实现过程

操作系统：ubuntu 10.04

交叉编译环境：arm-linux-gcc 4.3.2 ，安装位置 /usr/local/arm/4.3.2/

6410板子内核源码路径：~/Desktop/linux-3.0.1

目标板环境 ：OK6410-A linux3.0.1

driver_led.c

1. #include <linux/module.h>
2.
3. #include <linux/kernel.h>
4. #include <linux/fs.h>
5. #include <asm/uaccess.h>
6. #include <linux/miscdevice.h>
7. #include <linux/pci.h>
8. #include <mach/map.h>
9. #include <mach/regs-gpio.h>
10. #include <mach/gpio-bank-m.h>
11. #include <plat/gpio-cfg.h>
12.
13. #define LED_MAJOR 240
14.
15. int led_open (struct inode *inode,struct file *filp)
16.
17. {
18. unsigned tmp;
19. tmp = readl(S3C64XX_GPMCON);
20. tmp = (tmp & ~(0x7U<<1))|(0x1U);
21. writel(tmp, S3C64XX_GPMCON);
22. printk("#########open######\n");
23. return 0;
24. }
25.
26. ssize_t led_read (struct file *filp, char __user *buf, size_t count,loff_t *f_pos)
27. {
28. printk("#########read######\n");
29. return count;
30. }
31.
32.
33. ssize_t led_write (struct file *filp, const char __user *buf, size_t count,loff_t *f_pos)
34. {
35. char wbuf[10];
36. unsigned tmp;
37. printk("#########write######\n");
38. copy_from_user(wbuf,buf,count);
39. switch(wbuf[0])
40. {
41. case 0: //off
42. tmp = readl(S3C64XX_GPMDAT);
43. tmp |= (0x1U);
44. writel(tmp, S3C64XX_GPMDAT);
45. break;
46. case 1: //on
47. tmp = readl(S3C64XX_GPMDAT);
48. tmp &= ~(0x1U);
49. writel(tmp, S3C64XX_GPMDAT);
50. break;
51. default :
52. break;
53. }
54. return count;
55. }
56.
57. int led_release (struct inode *inode, struct file *filp)
58. {
59. printk("#########release######\n");
60. return 0;
61. }
62.
63. struct file_operations led_fops ={
64. .owner = THIS_MODULE,
65. .open = led_open,
66. .read = led_read,
67. .write = led_write,
68. .release = led_release,
69. } ;
70.
71. int __init led_init (void)
72. { int rc;
73. printk ("Test led dev\n");
74. rc = register_chrdev(LED_MAJOR,"led",&led_fops);
75. if (rc <0)
76. {
77. printk ("register %s char dev error\n","led");
78. return -1;
79. }
80. printk ("ok!\n");
81. return
82. }
83.
84. void __exit led_exit (void)
85. {
86. unregister_chrdev(LED_MAJOR,"led");
87. printk ("module exit\n");
88. return ;
89. }
90.
91. module_init(led_init);
92. module_exit(led_exit);

Makefile

1. obj-m := driver_led.o
2. KDIR := ~/Desktop/linux-3.0.1
3. all:
4. make -C $(KDIR) M=$(shell pwd) modules
5. install:
6. cp driver_led.ko /tftpboot/
7. clean:
8. make -C $(KDIR) M=$(shell pwd) clean

test.c

1. #include <stdio.h>
2. #include <sys/types.h>
3. #include <sys/stat.h>
4. #include <fcntl.h>
5. int main (void)
6. {
7. int fd;
8. char buf[10]={0,1} ;
9. fd = open("/dev/my_led",O_RDWR);
10. if (fd < 0)
11. {
12. printf ("Open /dev/my_led file error\n");
13. return -1;
14. }
15. while(1)
16. {
17. write(fd,&buf[0],1);
18. sleep(1);
19. write(fd,&buf[1],1);
20. sleep(1);
21. }
22. close (fd);
23. return 0;
24.
25. }

源码下#make生成.ko文件

编译测试程序 #arm-linux-gcc test.c -o test 交叉编译器最好放在/usr/local/arm/.. 解压时加上参数-C/即可。

然后加载驱动 #insmod 系统内核和编译出驱动的内核要一致，不然报错invalid format

创建设备#mknod /dev/my_led c 240 0

运行应用程序

./test

观察到闪烁LED灯。