mini6410 實現簡單 adc驅動--友善版

在Linux設備驅動學習中，在參考別人的源碼，會達到很好的學習效果。在這篇文章中我列出了友善之臂中的驅動程序和自己寫的注釋。

在後續的章節中會有本人muge0913驅動程序發放，簡單易懂的程序，幫大家向嵌入式步步靠近。

1. #include <linux/kernel.h>
2. #include <linux/module.h>
3. #include <linux/slab.h>
4. #include <linux/input.h>
5. #include <linux/init.h>
6. #include <linux/errno.h>
7. #include <linux/serio.h>
8. #include <linux/delay.h>
9. #include <linux/clk.h>
10. #include <linux/wait.h>
11. #include <linux/sched.h>
12. #include <linux/cdev.h>
13. #include <linux/miscdevice.h>
15. #include <asm/io.h>
16. #include <asm/irq.h>
17. #include <asm/uaccess.h>
19. #include <mach/map.h>
20. #include <mach/regs-clock.h>
21. #include <mach/regs-gpio.h>
22. #include <plat/regs-timer.h>
23. #include <plat/regs-adc.h>
25. #undef DEBUG
26. //#define DEBUG
27. #ifdef DEBUG
28. #define DPRINTK(x...) {printk(__FUNCTION__"(%d): ",__LINE__);printk(##x);}
29. #else
30. #define DPRINTK(x...) (void)(0)
31. #endif
33. #define DEVICE_NAME "adc"
35. static void __iomem *base_addr;
37. typedef struct {
38. wait_queue_head_t wait;
39. int channel;
40. int prescale;
41. } ADC_DEV;
43. #ifdef CONFIG_TOUCHSCREEN_MINI6410
44. extern int mini6410_adc_acquire_io(void);
45. extern void mini6410_adc_release_io(void);
46. #else
47. static inline int mini6410_adc_acquire_io(void) {
48. return 0;
49. }
50. static inline void mini6410_adc_release_io(void) {
51. /* Nothing */
52. }
53. #endif
55. static int __ADC_locked = 0;
57. static ADC_DEV adcdev;
58. static volatile int ev_adc = 0;
59. static int adc_data;
61. static struct clk *adc_clock;
63. #define __ADCREG(name) (*(volatile unsigned long *)(base_addr + name))
64. #define ADCCON __ADCREG(S3C_ADCCON) // ADC control
65. #define ADCTSC __ADCREG(S3C_ADCTSC) // ADC touch screen control
66. #define ADCDLY __ADCREG(S3C_ADCDLY) // ADC start or Interval Delay
67. #define ADCDAT0 __ADCREG(S3C_ADCDAT0) // ADC conversion data 0
68. #define ADCDAT1 __ADCREG(S3C_ADCDAT1) // ADC conversion data 1
69. #define ADCUPDN __ADCREG(S3C_ADCUPDN) // Stylus Up/Down interrupt status
71. #define PRESCALE_DIS (0 << 14)
72. #define PRESCALE_EN (1 << 14)
73. #define PRSCVL(x) ((x) << 6)
74. #define ADC_INPUT(x) ((x) << 3)
75. #define ADC_START (1 << 0)
76. #define ADC_ENDCVT (1 << 15)
78. #define START_ADC_AIN(ch, prescale) \
79. do { \
80. ADCCON = PRESCALE_EN | PRSCVL(prescale) | ADC_INPUT((ch)) ; \
81. ADCCON |= ADC_START; \
82. } while (0)
85. static irqreturn_t adcdone_int_handler(int irq, void *dev_id)
86. {
87. if (__ADC_locked) {
88. adc_data = ADCDAT0 & 0x3ff;
90. ev_adc = 1;
91. wake_up_interruptible(&adcdev.wait);
93. /* clear interrupt */
94. __raw_writel(0x0, base_addr + S3C_ADCCLRINT);
95. }
97. return IRQ_HANDLED;
98. }
100. static ssize_t s3c2410_adc_read(struct file *filp, char *buffer, size_t count, loff_t *ppos)
101. {
102. char str[20];
103. int value;
104. size_t len;
106. if (mini6410_adc_acquire_io() == 0) {
107. __ADC_locked = 1;
109. START_ADC_AIN(adcdev.channel, adcdev.prescale);
111. wait_event_interruptible(adcdev.wait, ev_adc);
112. ev_adc = 0;
114. DPRINTK("AIN[%d] = 0x%04x, %d\n", adcdev.channel, adc_data, ADCCON & 0x80 ? 1:0);
116. value = adc_data;
118. __ADC_locked = 0;
119. mini6410_adc_release_io();
120. } else {
121. value = -1;
122. }
124. len = sprintf(str, "%d\n", value);
125. if (count >= len) {
126. int r = copy_to_user(buffer, str, len);
127. return r ? r : len;
128. } else {
129. return -EINVAL;
130. }
131. }
133. static int s3c2410_adc_open(struct inode *inode, struct file *filp)
134. {
135. init_waitqueue_head(&(adcdev.wait));
137. adcdev.channel=0;
138. adcdev.prescale=0xff;
140. DPRINTK("adc opened\n");
141. return 0;
142. }
144. static int s3c2410_adc_release(struct inode *inode, struct file *filp)
145. {
146. DPRINTK("adc closed\n");
147. return 0;
148. }
151. static struct file_operations dev_fops = {
152. owner: THIS_MODULE,
153. open: s3c2410_adc_open,
154. read: s3c2410_adc_read,
155. release: s3c2410_adc_release,
156. };
158. static struct miscdevice misc = {
159. .minor = MISC_DYNAMIC_MINOR,
160. .name = DEVICE_NAME,
161. .fops = &dev_fops,
162. };
164. static int __init dev_init(void)
165. {
166. int ret;
168. base_addr = ioremap(SAMSUNG_PA_ADC, 0x20);
169. if (base_addr == NULL) {
170. printk(KERN_ERR "Failed to remap register block\n");
171. return -ENOMEM;
172. }
174. adc_clock = clk_get(NULL, "adc");
175. if (!adc_clock) {
176. printk(KERN_ERR "failed to get adc clock source\n");
177. return -ENOENT;
178. }
179. clk_enable(adc_clock);
181. /* normal ADC */
182. ADCTSC = 0;
184. ret = request_irq(IRQ_ADC, adcdone_int_handler, IRQF_SHARED, DEVICE_NAME, &adcdev);
185. if (ret) {
186. iounmap(base_addr);
187. return ret;
188. }
190. ret = misc_register(&misc);
192. printk (DEVICE_NAME"\tinitialized\n");
193. return ret;
194. }
196. static void __exit dev_exit(void)
197. {
198. free_irq(IRQ_ADC, &adcdev);
199. iounmap(base_addr);
201. if (adc_clock) {
202. clk_disable(adc_clock);
203. clk_put(adc_clock);
204. adc_clock = NULL;
205. }
207. misc_deregister(&misc);
208. }
210. module_init(dev_init);
211. module_exit(dev_exit);
213. MODULE_LICENSE("GPL");
214. MODULE_AUTHOR("muge0913");