在linux驱动中调用I2C的方法

最新推荐文章于 2022-09-28 23:05:18 发布

luckymxq

最新推荐文章于 2022-09-28 23:05:18 发布

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分类专栏： linux

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本文介绍了如何在Linux驱动程序中注册和使用I2C。首先，通过创建`i2c_board_info`结构体并注册I2C总线，接着在驱动中初始化`tda_client`结构体，实现`tda_probe`和`tda_remove`函数以进行设备探测和移除。然后，提供了读写函数`tda_i2c_write`和`tda_i2c_read`用于I2C传输。最后建议参考Linux内核中的I2C例子进行学习。

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一、在相应的平台文件中添加I2C的注册信息

1）、创建一个i2c_board_info结构体（平台文件目录Arch\arm\mach-xxx）

struct tda_platform_data //这可以随便定义自己想要的结构
{
unsigned char register0;
unsigned char register1;
unsigned char register2;
};

struct tda_platform_data tda_pdata

static struct i2c_board_info __initdata tda_i2c2_boardinfo[] =

{
{
I2C_BOARD_INFO("tda", 0x48),
.platform_data = &tda_pdata,
},
};

2）、注册

omap_register_i2c_bus(2, 400, tda_i2c2_boardinfo,ARRAY_SIZE(tda_i2c2_boardinfo)); //第一个参数是通道，第二个参数是速率(400KHz)

二、在驱动中以下信息

struct tda_client
{
struct i2c_client *client;
struct i2c_msg xfer_msg;
};
static struct tda_client tda001;

static int tda_remove(struct i2c_client *client)
{
struct tda_client *tda = &tda001;
if (tda->client && tda->client != client)
{
i2c_unregister_device(tda->client);
tda001.client = NULL;
}

return 0;
}

static int tda_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
struct tda_client *tda = &tda001;
if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C) == 0)
{
printk("can't talk I2C2\n");
return -1;
}
tda->client = client;
return 0;
}

static const struct i2c_device_id tda_ids[] =
{
{"tda",0},
{ },
};
MODULE_DEVICE_TABLE(i2c, tda_ids);

static struct i2c_driver tda_driver =
{
.driver.name = "TDA_DRIVER",
.id_table = tda_ids,
.probe = tda_probe,
.remove = tda_remove,
};

int Init_I2C2(void)
{
return i2c_add_driver(&tda_driver);
}

void Deinit_I2C2(void)
{
i2c_del_driver(&tda_driver);
}

三、添加读写函数

int tda_i2c_write(unsigned char reg,unsigned char value)
{
struct tda_client *tda = &tda001;
struct i2c_msg *msg;
int ret = 0;
msg = &tda->xfer_msg;
msg->addr= reg;
msg->len = 1;
msg->flags = 0;
msg->buf = &value;

ret = i2c_transfer(tda->client->adapter, &tda->xfer_msg, 1);
if(ret!=1)
return -1;
else
return 0;
}

int tda_i2c_read(unsigned char reg,unsigned char *value)
{
struct tda_client *tda = &tda001;
struct i2c_msg *msg;
int ret = 0;

msg = &tda->xfer_msg;
msg->addr= reg;
msg->len = 1;
msg->flags = 1;
msg->buf = value;

ret = i2c_transfer(tda->client->adapter, &tda->xfer_msg, 1);
if(ret!=1)
return -1;
else
return 0;
}