i2c client驱动

最新推荐文章于 2024-02-04 18:27:29 发布

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最新推荐文章于 2024-02-04 18:27:29 发布

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分类专栏： linux kernel driver 文章标签：驱动开发 linux 学习

本文链接：https://blog.youkuaiyun.com/baidxi/article/details/125861235

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本文介绍了Linux内核中的I2C设备驱动框架，包括关键的探针函数`foobar_i2c_probe`和移除函数`foobar_i2c_remove`。通过设备树配置，驱动能够匹配到指定的I2C设备，并在`probe`中分配和初始化设备数据结构。设备树示例展示了如何为I2C设备设置地址。

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I2C设备驱动框架

#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设备驱动框架本身比较简单，重要的是相对的子系统驱动		
I2C设备的设备树有点特别的地方，在probe的参数里的client里的addr在设备树里设置reg属性，		
设置了REG属性之后，在ADAPTER驱动PROBE的时候会自动填充client，如下图：

    i2c3:i2c@e1800000 {
        compatible = "s5pv210,i2c-adapter";
        #address-cells = <1>;
        #size-cells = <1>;
        mode = "i2c";
        reg = <0xe1800000 0x10>;
        foobar@0x46 {
            compatible = "dummy,foobar-device";
            reg = <0x46>;
        };  
    };