I2C設備驅動框架

#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/of.h>
#include <linux/of_device.h>

struct foobar_i2c_device_data {
    
    struct i2c_client *client;
    struct i2c_adapter *adap;
};

static int foobar_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
    
    struct i2c_adapter *adap = client->adapter;
    struct foobar_i2c_device_data *device;
    dev_info(&client->dev, "probe\n");

    device = devm_kzalloc(&client->dev, sizeof(*device), GFP_KERNEL);

    if (!device)
        return -ENOMEM;

    device->client = client;
    device->adap = adap;

    dev_info(&client->dev, "addr:%x\n", client->addr);

    i2c_set_clientdata(client, device);

    return 0;
}

static int foobar_i2c_remove(struct i2c_client *client)
{
    
    struct foobar_i2c_device_data *device = i2c_get_clientdata(client);
    return 0;
}

static const struct of_device_id foobar_of_match[] = {
    
    {
    
        .compatible ="dummy,foobar-device"
    },
    {
    
        /* */
    }
};

MODULE_DEVICE_TABLE(of, foobar_of_match);

const struct i2c_device_id foobar_id[] = {
    
    {
    
        .name = "foobar",
    },
    {
    
        /* */
    }
};

static struct i2c_driver foobar_driver = {
    
    .driver = {
    
        .name = "foobar",
        .of_match_table = of_match_ptr(foobar_of_match),
    },
    .probe = foobar_i2c_probe,
    .remove = foobar_i2c_remove,
    .id_table = foobar_id,
};

module_i2c_driver(foobar_driver);
MODULE_LICENSE("GPL");

	I2C設備驅動框架本身比較簡單，重要的是相對的子系統驅動		
I2C設備的設備樹有點特別的地方，在probe的參數裏的client裏的addr在設備樹裏設置reg屬性，		
設置了REG屬性之後，在ADAPTER驅動PROBE的時候會自動填充client，如下圖：

    i2c3:[email protected] {
    
        compatible = "s5pv210,i2c-adapter";
        #address-cells = <1>;
        #size-cells = <1>;
        mode = "i2c";
        reg = <0xe1800000 0x10>;
        [email protected]0x46 {
    
            compatible = "dummy,foobar-device";
            reg = <0x46>;
        };  
    };