Linux I2C总线控制器驱动(S3C2440)，i2cs3c2440

Linux I2C总线控制器驱动(S3C2440)，i2cs3c2440

 s3c2440的i2c控制器驱动(精简DIY)，直接上代码，注释很详细：

  1 #include <linux/kernel.h>
  2 #include <linux/module.h>
  3 
  4 #include <linux/i2c.h>
  5 #include <linux/init.h>
  6 #include <linux/time.h>
  7 #include <linux/interrupt.h>
  8 #include <linux/delay.h>
  9 #include <linux/errno.h>
 10 #include <linux/err.h>
 11 #include <linux/platform_device.h>
 12 #include <linux/pm_runtime.h>
 13 #include <linux/clk.h>
 14 #include <linux/cpufreq.h>
 15 #include <linux/slab.h>
 16 #include <linux/io.h>
 17 #include <linux/of_i2c.h>
 18 #include <linux/of_gpio.h>
 19 #include <plat/gpio-cfg.h>
 20 #include <mach/regs-gpio.h>
 21 
 22 #include <asm/irq.h>
 23 
 24 #include <plat/regs-iic.h>
 25 #include <plat/iic.h>
 26 
 27 //#define PRINTK printk
 28 #define PRINTK(...) 
 29 
 30 enum s3c24xx_i2c_state {
 31     STATE_IDLE,
 32     STATE_START,
 33     STATE_READ,
 34     STATE_WRITE,
 35     STATE_STOP
 36 };
 37 
 38 //i2c控制器寄存器
 39 struct s3c2440_i2c_regs {
 40     unsigned int iiccon;
 41     unsigned int iicstat;
 42     unsigned int iicadd;
 43     unsigned int iicds;
 44     unsigned int iiclc;
 45 };
 46 
 47 //i2c数据传输载体
 48 struct s3c2440_i2c_xfer_data {
 49     struct i2c_msg *msgs;
 50     int msn_num;
 51     int cur_msg;
 52     int cur_ptr;
 53     int state;
 54     int err;
 55     wait_queue_head_t wait;
 56 };
 57 
 58 static struct s3c2440_i2c_xfer_data s3c2440_i2c_xfer_data;
 59 
 60 
 61 static struct s3c2440_i2c_regs *s3c2440_i2c_regs;
 62 
 63 
 64 static void s3c2440_i2c_start(void)
 65 {
 66     s3c2440_i2c_xfer_data.state = STATE_START;
 67     
 68     if (s3c2440_i2c_xfer_data.msgs->flags & I2C_M_RD) /* 读 */
 69     {
 70         s3c2440_i2c_regs->iicds         = s3c2440_i2c_xfer_data.msgs->addr << 1;　
 71         s3c2440_i2c_regs->iicstat      = 0xb0;    // 主机接收，启动
 72     }
 73     else /* 写 */
 74     {
 75         s3c2440_i2c_regs->iicds         = s3c2440_i2c_xfer_data.msgs->addr << 1;
 76         s3c2440_i2c_regs->iicstat    = 0xf0;         // 主机发送，启动
 77     }
 78 }
 79 
 80 static void s3c2440_i2c_stop(int err)
 81 {
 82     s3c2440_i2c_xfer_data.state = STATE_STOP;
 83     s3c2440_i2c_xfer_data.err   = err;
 84 
 85     PRINTK("STATE_STOP, err = %d\n", err);
 86 
 87 
 88     if (s3c2440_i2c_xfer_data.msgs->flags & I2C_M_RD) /* 读 */
 89     {
 90         // 下面两行恢复I2C操作，发出P信号
 91         s3c2440_i2c_regs->iicstat = 0x90;
 92         s3c2440_i2c_regs->iiccon  = 0xaf;
 93         ndelay(50);  // 等待一段时间以便P信号已经发出
 94     }
 95     else /* 写 */
 96     {
 97         // 下面两行用来恢复I2C操作，发出P信号
 98         s3c2440_i2c_regs->iicstat = 0xd0;
 99         s3c2440_i2c_regs->iiccon  = 0xaf;
100         ndelay(50);  // 等待一段时间以便P信号已经发出
101     }
102 
103     /* 唤醒 */
104     wake_up(&s3c2440_i2c_xfer_data.wait);
105     
106 }
107 
108 //i2c总线数据传输处理函数
109 static int s3c2440_i2c_xfer(struct i2c_adapter *adap,
110             struct i2c_msg *msgs, int num)
111 {
112     unsigned long timeout;
113     
114     /* 把num个msg的I2C数据发送出去/读进来 */
115     s3c2440_i2c_xfer_data.msgs    = msgs;
116     s3c2440_i2c_xfer_data.msn_num = num;
117     s3c2440_i2c_xfer_data.cur_msg = 0;
118     s3c2440_i2c_xfer_data.cur_ptr = 0;
119     s3c2440_i2c_xfer_data.err     = -ENODEV; //确认是否有ack应答
120 
121     s3c2440_i2c_start();　//发出start信号，判断read or write
122 
123     /* 休眠-等待i2c读写状态改变 */
124     timeout = wait_event_timeout(s3c2440_i2c_xfer_data.wait, (s3c2440_i2c_xfer_data.state == STATE_STOP), HZ * 5);　//等待状态成立或5s
125     if (0 == timeout)
126     {
127         printk("s3c2440_i2c_xfer time out\n");
128         return -ETIMEDOUT;
129     }
130     else
131     {
132         return s3c2440_i2c_xfer_data.err;
133     }
134 }
135 
136 static u32 s3c2440_i2c_func(struct i2c_adapter *adap)
137 {
138     return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
139 }
140 
141 
142 static const struct i2c_algorithm s3c2440_i2c_algo = {
143 //    .smbus_xfer     = ,   //smbus是i2c传输的一个子集,支持的话可以在这里指定处理函数
144     .master_xfer    = s3c2440_i2c_xfer,　//传输函数
145     .functionality    = s3c2440_i2c_func,
146 };
147 
148 /* 1. 分配/设置i2c_adapter
149  */
150 static struct i2c_adapter s3c2440_i2c_adapter = {
151  .name             = "s3c2440_sheldon",
152  .algo             = &s3c2440_i2c_algo,　//算法函数
153  .owner          = THIS_MODULE,
154 };
155 
156 static int isLastMsg(void)
157 {
158     return (s3c2440_i2c_xfer_data.cur_msg == s3c2440_i2c_xfer_data.msn_num - 1);
159 }
160 
161 static int isEndData(void)
162 {
163     return (s3c2440_i2c_xfer_data.cur_ptr >= s3c2440_i2c_xfer_data.msgs->len);
164 }
165 
166 static int isLastData(void)
167 {
168     return (s3c2440_i2c_xfer_data.cur_ptr == s3c2440_i2c_xfer_data.msgs->len - 1);
169 }
170 
171 static irqreturn_t s3c2440_i2c_xfer_irq(int irq, void *dev_id)
172 {
173     unsigned int iicSt;
174         
175      iicSt  = s3c2440_i2c_regs->iicstat;  //读取i2c控制器的状态寄存器，判断是否读写成功
176 
177     if(iicSt & 0x8){ printk("Bus arbitration failed\n\r"); }
178 
179     switch (s3c2440_i2c_xfer_data.state)
180     {
181         case STATE_START : /* 发出S和设备地址后,产生中断 */
182         {
183             PRINTK("Start\n");
184             /* 如果没有ACK, 返回错误 */
185             if (iicSt & S3C2410_IICSTAT_LASTBIT)
186             {
187                 s3c2440_i2c_stop(-ENODEV);
188                 break;
189             }
190 
191             if (isLastMsg() && isEndData())
192             {
193                 s3c2440_i2c_stop(0);
194                 break;
195             }
196 
197             /* 进入下一个状态 */
198             if (s3c2440_i2c_xfer_data.msgs->flags & I2C_M_RD) /* 读 */
199             {
200                 s3c2440_i2c_xfer_data.state = STATE_READ;
201                 goto next_read;
202             }
203             else
204             {
205                 s3c2440_i2c_xfer_data.state = STATE_WRITE;
206             }    
207         }
208 
209         case STATE_WRITE:
210         {
211             PRINTK("STATE_WRITE\n");
212             /* 如果没有ACK, 返回错误 */
213             if (iicSt & S3C2410_IICSTAT_LASTBIT)
214             {
215                 s3c2440_i2c_stop(-ENODEV);
216                 break;
217             }
218 
219             if (!isEndData())  /* 如果当前msg还有数据要发送 */
220             {
221                 s3c2440_i2c_regs->iicds = s3c2440_i2c_xfer_data.msgs->buf[s3c2440_i2c_xfer_data.cur_ptr];
222                 s3c2440_i2c_xfer_data.cur_ptr++;
223                 
224                 // 将数据写入IICDS后，需要一段时间才能出现在SDA线上
225                 ndelay(50);    
226                 
227                 s3c2440_i2c_regs->iiccon = 0xaf;        // 恢复I2C传输
228                 break;                
229             }
230             else if (!isLastMsg())
231             {
232                 /* 开始处理下一个消息 */
233                 s3c2440_i2c_xfer_data.msgs++;
234                 s3c2440_i2c_xfer_data.cur_msg++;
235                 s3c2440_i2c_xfer_data.cur_ptr = 0;
236                 s3c2440_i2c_xfer_data.state = STATE_START;
237                 /* 发出START信号和发出设备地址 */
238                 s3c2440_i2c_start();
239                 break;
240             }
241             else
242             {
243                 /* 是最后一个消息的最后一个数据 */
244                 s3c2440_i2c_stop(0);
245                 break;                
246             }
247 
248             break;
249         }
250 
251         case STATE_READ:
252         {
253             PRINTK("STATE_READ\n");
254             /* 读出数据 */
255             s3c2440_i2c_xfer_data.msgs->buf[s3c2440_i2c_xfer_data.cur_ptr] = s3c2440_i2c_regs->iicds;            
256             s3c2440_i2c_xfer_data.cur_ptr++;
257 next_read:
258             if (!isEndData()) /* 如果数据没读写, 继续发起读操作 */
259             {
260                 if (isLastData())  /* 如果即将读的数据是最后一个, 不发ack */
261                 {
262                     s3c2440_i2c_regs->iiccon = 0x2f;   // 恢复I2C传输，接收到下一数据时无ACK
263                 }
264                 else
265                 {
266                     s3c2440_i2c_regs->iiccon = 0xaf;   // 恢复I2C传输，接收到下一数据时发出ACK
267                 }                
268                 break;
269             }
270             else if (!isLastMsg())
271             {
272                 /* 开始处理下一个消息 */
273                 s3c2440_i2c_xfer_data.msgs++;
274                 s3c2440_i2c_xfer_data.cur_msg++;
275                 s3c2440_i2c_xfer_data.cur_ptr = 0;
276                 s3c2440_i2c_xfer_data.state = STATE_START;
277                 /* 发出START信号和发出设备地址 */
278                 s3c2440_i2c_start();
279                 break;
280             }
281             else
282             {
283                 /* 是最后一个消息的最后一个数据 */
284                 s3c2440_i2c_stop(0);
285                 break;                                
286             }
287             break;
288         }
289 
290         default: break;
291     }
292 
293     /* 清中断 */
294     s3c2440_i2c_regs->iiccon &= ~(S3C2410_IICCON_IRQPEND);
295 
296     return IRQ_HANDLED;    
297 }
298 
299 
300 /*
301  * I2C初始化
302  */
303 static void s3c2440_i2c_init(void)
304 {
305     struct clk *clk;
306 
307     clk = clk_get(NULL, "i2c");
308     clk_enable(clk);
309     
310     // 选择引脚功能：GPE15:IICSDA, GPE14:IICSCL
311     　　　　s3c_gpio_cfgpin(S3C2410_GPE(14), S3C2410_GPE14_IICSCL);
312     s3c_gpio_cfgpin(S3C2410_GPE(15), S3C2410_GPE15_IICSDA);
313 
314     /* bit[7] = 1, 使能ACK
315      * bit[6] = 0, IICCLK = PCLK/16
316      * bit[5] = 1, 使能中断
317      * bit[3:0] = 0xf, Tx clock = IICCLK/16
318      * PCLK = 50MHz, IICCLK = 3.125MHz, Tx Clock = 0.195MHz
319      */
320     s3c2440_i2c_regs->iiccon = (1<<7) | (0<<6) | (1<<5) | (0xf);  // 0xaf
321 
322     s3c2440_i2c_regs->iicadd  = 0x10;     // S3C24xx slave address = [7:1]
323     s3c2440_i2c_regs->iicstat = 0x10;     // I2C串行输出使能(Rx/Tx)
324 }
325 
326 static int i2c_bus_s3c2440_init(void)
327 {
328     /* 2. 硬件相关的设置 */
329     s3c2440_i2c_regs = ioremap(0x54000000, sizeof(struct s3c2440_i2c_regs));//映射功能寄存器
330     
331     s3c2440_i2c_init(); //初始化i2c控制器
332 
333     request_irq(IRQ_IIC, s3c2440_i2c_xfer_irq, 0, "s3c2440-i2c", NULL);　//申请中断源,加载中断处理函数－s3c2440_i2c_xfer_irq
334 
335     init_waitqueue_head(&s3c2440_i2c_xfer_data.wait); //初始化一个等待队列头
336     
337     /* 3. 注册i2c_adapter */
338     i2c_add_adapter(&s3c2440_i2c_adapter);
339     
340     return 0;
341 }
342 
343 static void i2c_bus_s3c2440_exit(void)
344 {
345     i2c_del_adapter(&s3c2440_i2c_adapter);    
346     free_irq(IRQ_IIC, NULL);
347     iounmap(s3c2440_i2c_regs);
348 }
349 
350 module_init(i2c_bus_s3c2440_init);
351 module_exit(i2c_bus_s3c2440_exit);
352 MODULE_LICENSE("GPL");

附一份测试程序：

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #include <sys/types.h>
 5 #include <sys/stat.h>
 6 #include <fcntl.h>
 7 #include "i2c-dev.h"
 8 
 9 
10 /* i2c_usr_test </dev/i2c-0> <dev_addr> r addr
11  * i2c_usr_test </dev/i2c-0> <dev_addr> w addr val
12  */
13 
14 void print_usage(char *file)
15 {
16     printf("%s </dev/i2c-0> <dev_addr> r addr\n", file);
17     printf("%s </dev/i2c-0> <dev_addr> w addr val\n", file);
18 }
19 
20 int main(int argc, char **argv)
21 {
22     int fd;
23     unsigned char addr, data;
24     int dev_addr;
25     
26     if ((argc != 5) && (argc != 6))
27     {
28         print_usage(argv[0]);
29         return -1;
30     }
31 
32     fd = open(argv[1], O_RDWR);
33     if (fd < 0)
34     {
35         printf("can't open %s\n", argv[1]);
36         return -1;
37     }
38 
39     dev_addr = strtoul(argv[2], NULL, 0);
40     if (ioctl(fd, I2C_SLAVE, dev_addr) < 0)
41     {    
42         /* ERROR HANDLING; you can check errno to see what went wrong */    
43         printf("set addr error!\n");
44         return -1;
45     }
46 
47     if (strcmp(argv[3], "r") == 0)
48     {
49         addr = strtoul(argv[4], NULL, 0);
50         
51         data = i2c_smbus_read_word_data(fd, addr);
52             
53         printf("data: %c, %d, 0x%2x\n", data, data, data);
54     }
55     else if ((strcmp(argv[3], "w") == 0) && (argc == 6))
56     {
57         addr = strtoul(argv[4], NULL, 0);
58         data = strtoul(argv[5], NULL, 0);
59         i2c_smbus_write_byte_data(fd, addr, data);        
60     }
61     else
62     {
63         print_usage(argv[0]);
64         return -1;
65     }
66     
67     return 0;
68 }

Make File:

KERN_DIR = /work/system/linux-3.4.2

all:
    make -C $(KERN_DIR) M=`pwd` modules 

clean:
    make -C $(KERN_DIR) M=`pwd` modules clean
    rm -rf modules.order

obj-m    += i2c_bus_s3c2440.o