[RK3288][Android6.0] 调试笔记 --- 测试I2C设备正常传输方法【转】

本文转载自：http://blog.csdn.net/kris_fei/article/details/71515020

Platform: Rockchip
OS: Android 6.0
Kernel: 3.10.92

rk在驱动层做了一个通用i2c测试代码提供给上层快速测试i2c外设是否传输正常.

测试使用方法:
#echo [0-5] > /dev/i2c_detect //0-5表示i2c number号,不过i2c5需要修改下驱动,默认只支持到i2c4.
例如我的i2c2接的是audio codec:

[plain] view plain copy

&i2c2 {

status = "okay";

rt5631: rt5631@1a {

compatible = "rt5631";

reg = <0x1a>;

};

};

root@rk3288:/ # echo 2 > /dev/i2c_detect
kernel log出打印:
I2c2 slave list: 0x1a
而audio codec的地址就是0x1a.

驱动关键点说明:
kernel/drivers/i2c/buses/i2c-rockchip.c:

[cpp] view plain copy

static ssize_t i2c_detect_write(struct file *file,

const char __user *buf, size_t count, loff_t *offset)

{

char nr_buf[8];

int nr = 0, ret;

/*只支持到i2c4, 如果要支持i2c5,那么要改成5.*/

if (count > 4)

return -EFAULT;

ret = copy_from_user(nr_buf, buf, count);

if (ret < 0)

return -EFAULT;

sscanf(nr_buf, "%d", &nr);

/*这里得改成6. */

if (nr >= 5 || nr < 0)

return -EFAULT;

slave_detect(nr);

return count;

}

static void slave_detect(int nr)

{

int ret = 0;

unsigned short addr;

char val[8];

char buf[6 * 0x80 + 20];

struct i2c_client client;

memset(buf, 0, 6 * 0x80 + 20);

sprintf(buf, "I2c%d slave list: ", nr);

do {

/*扫描0x01~0x80地址范围的设备.*/

for (addr = 0x01; addr < 0x80; addr++) {

detect_set_client(&client, addr, nr);

/*读取一个字节.*/

ret = detect_read(&client, val, 1);

if (ret > 0)

sprintf(buf, "%s 0x%02x", buf, addr);

}

/*打印扫描到的设备地址.*/

printk("%s\n", buf);

}

while (0);

}

static int detect_read(struct i2c_client *client, char *buf, int len)

{

struct i2c_msg msg;

msg.addr = client->addr;

msg.flags = client->flags | I2C_M_RD;

msg.buf = buf;

msg.len = len;

/*以100kHz的速率读取*/

#ifdef CONFIG_I2C_ROCKCHIP_COMPAT

msg.scl_rate = 100 * 1000;

#endif

return i2c_transfer(client->adapter, &msg, 1);

}

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