mini2440 LED驱动程序

alleincao

    mini2440中提供的内核自带了LED的驱动程序，但该驱动是以杂项设备的形式编写，不太适合初学者，作者因为教学工作需要，花了一点时间，根据LDD3第三章内容将代码进行了修改，希望对一些初学者有所帮助。

    注意：本案例中采用了mdev设备文件管理系统以自动生成设备节点，有兴趣的同仁可以参考本博客关于mdev的相关介绍，对于初学者，不理解的可以手动创建设备节点进行本程序的测试。

    硬件连接如下，依次对应CPU上的GPB5～GPB8引脚：

    驱动程序：

2. #include <linux/miscdevice.h>
3. #include <linux/delay.h>
4. #include <asm/irq.h>
5. #include <mach/regs-gpio.h>
6. #include <mach/hardware.h>
7. #include <linux/kernel.h>
8. #include <linux/module.h>
9. #include <linux/init.h>
10. #include <linux/mm.h>
11. #include <linux/fs.h>
12. #include <linux/types.h>
13. #include <linux/delay.h>
14. #include <linux/moduleparam.h>
15. #include <linux/slab.h>
16. #include <linux/errno.h>
17. #include <linux/ioctl.h>
18. #include <linux/cdev.h>
19. #include <linux/string.h>
20. #include <linux/list.h>
21. #include <linux/pci.h>
22. #include <linux/gpio.h>
23. #include <asm/uaccess.h>
24. #include <asm/atomic.h>
25. #include <asm/unistd.h>
26. 
    
27. #include <linux/device.h> //用于mdev操作
28. 
    
29. 
    
30. #define DEVICE_NAME "leds"
31. 
    
32. 
    
33. unsigned int gpio_major_number=0;
34. struct cdev gpio_dev;
35. struct class *gpio_class;
36. dev_t dev_nr;
37. 
    
38. 
    
39. static unsigned long led_table [] = {
40. S3C2410_GPB(5),
41. S3C2410_GPB(6),
42. S3C2410_GPB(7),
43. S3C2410_GPB(8),
44. };
45. 
    
46. static unsigned int led_cfg_table [] = {
47. S3C2410_GPIO_OUTPUT,
48. S3C2410_GPIO_OUTPUT,
49. S3C2410_GPIO_OUTPUT,
50. S3C2410_GPIO_OUTPUT,
51. };
52. 
    
53. static int sbc2440_leds_ioctl(
54. struct inode *inode, 
55. struct file *file, 
56. unsigned int cmd, 
57. unsigned long arg)
58. {
59. switch(cmd) {
60. case 0:
61. case 1:
62. if (arg > 4) {
63. return -EINVAL;
64. }
65. s3c2410_gpio_setpin(led_table[arg], !cmd);
66. return 0;
67. default:
68. return -EINVAL;
69. }
70. }
71. 
    
72. static struct file_operations gpio_fops = {
73. .owner = THIS_MODULE,
74. .ioctl = sbc2440_leds_ioctl,
75. };
76. 
    
77. static int __init dev_init(void)
78. {
79. int ret,i;
80. 
    
81. for (i = 0; i < 4; i++) { //引脚初始化
82. s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);
83. s3c2410_gpio_setpin(led_table[i], 0);
84. }
85. 
    
86. ret = alloc_chrdev_region(&dev_nr,0,1,DEVICE_NAME); //动态分配设备号
87. gpio_major_number = MAJOR(dev_nr);
88. printk(KERN_INFO "Major Num ->%d\n",gpio_major_number);
89. if (ret<0) 
90. {
91. printk(KERN_WARNING "gpio:can't get major number %d/n",gpio_major_number);
92. return ret;
93. }
94. 
    
95. cdev_init(&gpio_dev,&gpio_fops); //初始化并向系统添加字符设备
96. gpio_dev.owner = THIS_MODULE;
97. // gpio_dev.ops   = &gpio_fops;
98. ret = cdev_add(&gpio_dev,dev_nr,1);
99. if (ret) 
100. {
101. unregister_chrdev_region(dev_nr,1);
102. printk(KERN_NOTICE "Error %d adding gpio device/n",ret);
103. return ret;
104. }
106. gpio_class = class_create(THIS_MODULE, "gpio_class"); //mdev相关，用于自动创建设备节点
107. if(IS_ERR(gpio_class)) 
108. {
109. printk("Err: failed in creating class./n");
110. return -1;
111. }
112. /* register your own device in sysfs, and this will cause mdev to create corresponding device node */
113. device_create(gpio_class,NULL,dev_nr, NULL, "gpio_dev%d" ,0);//设备节点名称gpio_dev0
114. 
     
115. return 0;
116. }
117. 
     
118. static void __exit dev_exit(void)
119. {
120. cdev_del(&gpio_dev);
121. device_destroy(gpio_class,dev_nr);
122. class_destroy(gpio_class);
123. unregister_chrdev_region(dev_nr,1);
124. }
125. 
     
126. 
     
127. module_init(dev_init);
128. module_exit(dev_exit);
129. MODULE_LICENSE("GPL");
130. MODULE_AUTHOR("Allein.Cao");

测试程序：

1. #include <stdio.h>
   
2. #include <stdlib.h>
   
3. #include <unistd.h>
   
4. #include <sys/ioctl.h>
   
5. 
   
6. int main(int argc, char **argv)
   
7. {
   
8.         int on;
   
9.         int led_no;
   
10.         int fd;
    
11.         if (argc != 3 || sscanf(argv[1], "%d", &led_no) != 1 || sscanf(argv[2],"%d", &on) != 1 ||
    
12.             on < 0 || on > 1 || led_no < 0 || led_no > 3) {
    
13.                 fprintf(stderr, "Usage: leds led_no 0|1\n");
    
14.                 exit(1);
    
15.         }
    
16. 
    
17.         fd = open("/dev/gpio_dev0", 0); //打开设备节点，需与驱动程序对应起来
    
18.         if (fd < 0) {
19.                 perror("open device leds");
    
20.                 exit(1);
    
21.         }
    
22.         ioctl(fd, on, led_no);
    
23.         close(fd);
    
24.         return 0;
    
25. }