i2c 内核驱动程序 - sysfs kobject 和 i2c_client 之间的绑定

Question

我正在研究 I2C 内核驱动程序，并希望在新文件夹中提供一个 sysfs 文件接口 - /sys/devices/MySensor。但是，当我这样做时，我不知道如何将 i2c 客户端与新的 kobject 相关联。

因此，当调用我的设备属性函数时，传入的设备对象不允许我检索已注册的 i2c 客户端。

我声明我的属性如下：

static ssize_t my_sensor_do_something(struct device *dev, struct device_attribute *attr, char *buf)

{
    struct i2c_client *client;
    struct my_sensor_data *data;
    int size = 0;

    client = to_i2c_client(dev);

    my_sensor_dbgmsg("Client Address:0x%02x\n", client->addr);

    data = i2c_get_clientdata(client);

    return 0
}
static DEVICE_ATTR(do_something, S_IRUGO, my_sensor_do_something, NULL);

static struct attribute *my_sensor_attributes[] = {
    &dev_attr_do_something.attr,
    NULL
};

static const struct attribute_group my_sensor_attr_group = {
    .attrs = my_sensor_attributes,
};

然后，在我的探测功能中，创建我的子文件夹

struct device *my_dev = root_device_register("my_sensor");
err = sysfs_create_group(&my_dev->kobj, &my_sensor_attr_group);

子文件夹和 do_something 文件在 /sys/kernel/ 中创建，但是当调用 do_something() 时，尝试检索 I2C 客户端失败 - client->地址为 0 且 i2c_get_client_data returns 为空。

关于信息，i2c 设备在设备树中定义，我可以成功地将设备属性添加到现有文件夹中

err = sysfs_create_group(client->dev.kobj, &my_sensor_attr_group);
/sys/bus/i2c/devices/i2c-7/7-004c/

如果这个问题含糊不清或缺乏足够的细节，我们深表歉意。我对此比较陌生。

有没有人知道我在创建新的 sysfs 文件夹时遗漏了什么，以便将其与我注册的 i2c 客户端相关联？

谢谢

Answer 1

您可以在初始化时将 client 放在 my_dev 上。

dev_set_drvdata(my_dev, client);

然后在my_sensor_do_something函数中，用dev_get_drvdata把client取出来

client = dev_get_drvdata(dev);

完整示例如下

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>

static ssize_t my_sensor_do_something(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
    struct i2c_client *client;
    void *data;

    client = dev_get_drvdata(dev);
    data = i2c_get_clientdata(client);
    pr_info("Client Address:0x%02x Data:%p\n", client->addr, data);

    return 0;
}

static DEVICE_ATTR(do_something, 0444, my_sensor_do_something, NULL);

static struct attribute *my_sensor_attributes[] = {
    &dev_attr_do_something.attr,
    NULL
};

static const struct attribute_group my_sensor_attr_group = {
    .attrs = my_sensor_attributes,
};

static struct device *my_dev;
static void my_sensor_create(struct i2c_client *client)
{
    int err;

    my_dev = root_device_register("my_sensor");
    dev_set_drvdata(my_dev, client);
    err = sysfs_create_group(&my_dev->kobj, &my_sensor_attr_group);
    if (err)
            pr_info("sysfs_create_group failure.\n");
}

struct test_device {
    struct i2c_client *client;
};

static int test_i2c_probe(struct i2c_client *client,
                      const struct i2c_device_id *id)
{
    struct test_device *dev;

    dev = kzalloc(sizeof(struct test_device), GFP_KERNEL);
    if (dev == NULL)
            return -ENOMEM;

    dev->client = client;
    i2c_set_clientdata(client, dev);
    my_sensor_create(client);

    return 0;
}

static int test_i2c_remove(struct i2c_client *client)
{
    struct test_client *dev = i2c_get_clientdata(client);

    if (my_dev)
            root_device_unregister(my_dev);

    kfree(dev);
    return 0;
}

static const struct i2c_device_id test_i2c_id[] = {
    {"test_i2c_client", 0},
    {}
};

static struct i2c_driver test_i2c_driver = {
    .driver   = { .name = "test_i2c_client", },
    .probe    = test_i2c_probe,
    .remove   = test_i2c_remove,
    .id_table = test_i2c_id,
};

static int __init test_i2c_init_driver(void)
{
    return i2c_add_driver(&test_i2c_driver);
}

static void __exit test_i2c_exit_driver(void)
{
    i2c_del_driver(&test_i2c_driver);
}

module_init(test_i2c_init_driver);
module_exit(test_i2c_exit_driver);

MODULE_LICENSE("GPL");

i2c 内核驱动程序 - sysfs kobject 和 i2c_client 之间的绑定

i2c kernel driver - Binding between sysfs kobject and i2c_client

linux

kernel

i2c

sysfs