Linux使用設備樹的i2c驅動與設備匹配方式

Linux使用設備樹的i2c驅動與設備匹配有3種方式：

• of_driver_match_device
• acpi_driver_match_device
• i2c_match_id

源碼：

static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
        struct i2c_client       *client = i2c_verify_client(dev);
        struct i2c_driver       *driver;

        if (!client)
                return 0;

        /* Attempt an OF style match */
        if (of_driver_match_device(dev, drv))
                return 1;

        /* Then ACPI style match */
        if (acpi_driver_match_device(dev, drv))
                return 1;

        driver = to_i2c_driver(drv);
        /* match on an id table if there is one */
        if (driver->id_table)
                return i2c_match_id(driver->id_table, client) != NULL;

        return 0;
}

一、of_driver_match_device

這種方式是所有驅動匹配通用的，使用of_device_id 的compatible部分字符

struct of_device_id
{
    char    name[32];
    char    type[32];
    char    compatible[128];
    const void *data;
};

dts ：

        i2c0: i2c@01c2ac00 {  /* 控制器的設備節點 */
        ...
            mydht12 {   /* 增加的設備子節點  */
                compatible = "mydht12";
                reg = <0x5c>; /* 設備地址 */
            };

        };

驅動 ：

struct of_device_id ids[] = {
    {.compatible = "mydht12"},
    {},
};

struct i2c_driver mydrv = {
    .probe_new = probe, 
    .remove = remove,

    .driver = {
        .owner = THIS_MODULE,
        .name = "mydrv",
        .of_match_table = ids,
    },
};

二、acpi_driver_match_device

主要用於電源管理，很少用到，這裏不做介紹。

三、i2c_match_id

I2C設備特有匹配方式，使用i2c_device_id ：

struct i2c_device_id {
    char name[I2C_NAME_SIZE];
    kernel_ulong_t driver_data;    /* Data private to the driver */
};

struct i2c_device_id ids2[] = {
    {"mydht12"},
    {},
};

struct i2c_driver mydrv = {
    .probe_new = probe,
    .remove = remove,

    .driver = {
        .owner = THIS_MODULE,
        .name = "mydrv",
//      .of_match_table = ids,
    },
    .id_table = ids2,  //使用id_table匹配
};