第一個Linux驅動-流水燈

本節介紹如何利用板載的Led和Linux的內核定時器實現一個簡單的流水燈的驅動，所使用的開發板是TQ2440，內核版本2.6.30.4。

程序比較簡單，也沒涉及到什麼機制，直接上代碼了！關於定時器的使用模板可以參考<<Linux設備驅動開發詳解>>（見http://www.linuxidc.com/Linux/2011-07/38211.htm）.

驅動程序：

1. #include<linux/module.h>
2. #include<linux/init.h>
3. #include<linux/types.h>
4. #include<linux/fs.h>
5. #include<linux/mm.h>
6. #include<linux/cdev.h>
7. #include<linux/slab.h>
8. #include<linux/timer.h>
9. #include<linux/jiffies.h>
10. #include<asm/io.h>
11. #include<asm/uaccess.h>
12. #include<mach/regs-gpio.h>
15. #define LED_MAJOR 244
18. #define LED_ON 0
19. #define LED_OFF 1
21. #define LED1_PIN S3C2410_GPB5
22. #define LED2_PIN S3C2410_GPB6
23. #define LED3_PIN S3C2410_GPB7
24. #define LED4_PIN S3C2410_GPB8
26. static unsigned long led_major = LED_MAJOR;
28. struct led_dev
29. {
30. struct cdev cdev;
31. struct timer_list s_timer;
32. atomic_t led_no; //LED編號
33. atomic_t sec_counter; //秒計時數
34. };
36. struct led_dev *led_devp;
40. void led_control(int led_no)
41. {
42. switch(led_no)
43. {
44. case 1:s3c2410_gpio_setpin(LED1_PIN,LED_ON);
45. s3c2410_gpio_setpin(LED2_PIN,LED_OFF);
46. s3c2410_gpio_setpin(LED3_PIN,LED_OFF);
47. s3c2410_gpio_setpin(LED4_PIN,LED_OFF);
48. break;
49. case 2:s3c2410_gpio_setpin(LED1_PIN,LED_OFF);
50. s3c2410_gpio_setpin(LED2_PIN,LED_ON);
51. s3c2410_gpio_setpin(LED3_PIN,LED_OFF);
52. s3c2410_gpio_setpin(LED4_PIN,LED_OFF);
53. break;
54. case 3:s3c2410_gpio_setpin(LED1_PIN,LED_OFF);
55. s3c2410_gpio_setpin(LED2_PIN,LED_OFF);
56. s3c2410_gpio_setpin(LED3_PIN,LED_ON);
57. s3c2410_gpio_setpin(LED4_PIN,LED_OFF);
58. break;
59. case 4:s3c2410_gpio_setpin(LED1_PIN,LED_OFF);
60. s3c2410_gpio_setpin(LED2_PIN,LED_OFF);
61. s3c2410_gpio_setpin(LED3_PIN,LED_OFF);
62. s3c2410_gpio_setpin(LED4_PIN,LED_ON);
63. break;
64. default:break;
66. }
67. }
70. //定時器處理函數
71. static void sec_timer_handler(unsigned long arg)
72. {
73. int num;
75. mod_timer(&led_devp->s_timer,jiffies+HZ);
77. num = atomic_read(&led_devp->led_no);
78. if(num == 4)
79. {
80. atomic_set(&led_devp->led_no,1);
81. }
82. else
83. {
84. atomic_inc(&led_devp->led_no);
85. }
87. num = atomic_read(&led_devp->led_no);
88. led_control(num);
90. atomic_inc(&led_devp->sec_counter);
91. num = atomic_read(&led_devp->sec_counter);
92. printk(KERN_INFO "sec_count:%d\n",num);
94. }
97. static int led_open(struct inode *inode,struct file *filp)
98. {
99. struct timer_list *timer;
101. timer = &led_devp->s_timer;
102. init_timer(timer);
103. timer->function = sec_timer_handler;
104. timer->expires = jiffies+HZ; //計時頻率為HZ
106. add_timer(timer);
107. atomic_set(&led_devp->sec_counter,0);
108. atomic_set(&led_devp->led_no,0);
110. return 0;
112. }
116. static int led_release(struct inode *inode, struct file *filp)
117. {
118. del_timer(&led_devp->s_timer);
119. return 0;
120. }
124. static ssize_t led_read(struct file *filp, char __user *buf,
125. size_t size, loff_t *ppos)
126. {
127. int count,led_no;
128. int result;
130. count = atomic_read(&led_devp->sec_counter);
131. led_no = atomic_read(&led_devp->led_no);
132. result = (count<<3)+led_no;
134. if(put_user(result,(int*)buf))
135. {
136. return -EFAULT;
137. }
138. else
139. {
140. return sizeof(int);
141. }
142. }
147. static const struct file_operations led_fops =
148. {
149. .owner = THIS_MODULE,
150. .read = led_read,
151. .open = led_open,
152. .release = led_release,
153. };
158. static void led_setup_cdev(struct led_dev *dev, int index)
159. {
160. int err,devno = MKDEV(led_major,index);
161. cdev_init(&dev->cdev,&led_fops);
162. dev->cdev.owner = THIS_MODULE;
163. err = cdev_add(&dev->cdev,devno,1);
165. if(err)
166. {
167. printk(KERN_NOTICE "Error %d adding %d\n",err,index);
168. }
169. }
174. static int led_init(void)
175. {
176. int result;
178. dev_t devno = MKDEV(led_major,0); //獲取設備號
180. /*注冊設備*/
181. if(led_major)
182. result = register_chrdev_region(devno,1,"led");
183. else
184. {
185. result = alloc_chrdev_region(&devno,0,1,"led");
186. led_major = MAJOR(devno);
187. }
189. if(result<0)
190. {
191. printk("register failed!");
192. return result;
193. }
196. led_devp =(struct led_dev*)kmalloc(sizeof(struct led_dev),GFP_KERNEL);
198. if(!led_devp)
199. {
200. result = -ENOMEM;
201. unregister_chrdev_region(devno,1);
202. }
203. memset(led_devp, 0 ,sizeof(struct led_dev));
205. led_setup_cdev(led_devp,0);
207. /*配置IO口*/
208. s3c2410_gpio_cfgpin(LED1_PIN,S3C2410_GPIO_OUTPUT);
209. s3c2410_gpio_cfgpin(LED2_PIN,S3C2410_GPIO_OUTPUT);
210. s3c2410_gpio_cfgpin(LED3_PIN,S3C2410_GPIO_OUTPUT);
211. s3c2410_gpio_cfgpin(LED4_PIN,S3C2410_GPIO_OUTPUT);
213. /*初始化IO電平*/
214. s3c2410_gpio_setpin(LED1_PIN,LED_OFF);
215. s3c2410_gpio_setpin(LED2_PIN,LED_OFF);
216. s3c2410_gpio_setpin(LED3_PIN,LED_OFF);
217. s3c2410_gpio_setpin(LED4_PIN,LED_OFF);
219. return 0;
220. }
224. static void led_exit(void)
225. {
226. cdev_del(&led_devp->cdev);
227. kfree(led_devp);
228. unregister_chrdev_region(MKDEV(led_major,0),1);
229. }
233. MODULE_LICENSE("GPL");
234. MODULE_AUTHOR("Vanbreaker");
236. module_init(led_init);
237. module_exit(led_exit);