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 write122 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5s125 if (0 == timeout)126 {127 printk("s3c2440_i2c_xfer time out\n");128 return -ETIMEDOUT;129 }130 else131 {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_adapter149 */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 else204 {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 else242 {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ACK263 }264 else265 {266 s3c2440_i2c_regs->iiccon = 0xaf; // 恢复I2C传输,接收到下一数据时发出ACK267 } 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 else282 {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:IICSCL311 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ACK315 * bit[6] = 0, IICCLK = PCLK/16316 * bit[5] = 1, 使能中断317 * bit[3:0] = 0xf, Tx clock = IICCLK/16318 * PCLK = 50MHz, IICCLK = 3.125MHz, Tx Clock = 0.195MHz319 */320 s3c2440_i2c_regs->iiccon = (1<<7) | (0<<6) | (1<<5) | (0xf); // 0xaf321 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_irq334 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 addr11 * i2c_usr_test </dev/i2c-0> <dev_addr> w addr val12 */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 else62 {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
原标题:Linux I2C总线控制器驱动(S3C2440)
关键词:linux