c语言，结构体里面的函数

以linux-3.2内核代码为例，结构体里面的函数的用法：

例，在某驱动文件中，定义了一个平台设备驱动：

static struct platform_driver s3c24xx_led_driver = {
    .probe        = s3c24xx_led_probe,
    .remove        = s3c24xx_led_remove,
    .driver        = {
        .name        = "s3c24xx_led",
        .owner        = THIS_MODULE,
    },
};

对struct platform_driver而言，probe平台设备注册时需要的函数，remove是平台设备移除时时需要的函数。对于不同的硬件，其注册和移除的时候，有各自不同的部分操作，比如硬件上拉下拉、特殊寄存器cfg配置等。这些不同的操作就体现在例子中的s3c24xx_led_probe, s3c24xx_led_remove中。

static int s3c24xx_led_remove(struct platform_device *dev)
{
	struct s3c24xx_gpio_led *led = pdev_to_gpio(dev);

	led_classdev_unregister(&led->cdev);
	kfree(led);

	return 0;
}

static int s3c24xx_led_probe(struct platform_device *dev)
{
	struct s3c24xx_led_platdata *pdata = dev->dev.platform_data;
	struct s3c24xx_gpio_led *led;
	int ret;

	led = kzalloc(sizeof(struct s3c24xx_gpio_led), GFP_KERNEL);
	if (led == NULL) {
		dev_err(&dev->dev, "No memory for device\n");
		return -ENOMEM;
	}

	platform_set_drvdata(dev, led);

	led->cdev.brightness_set = s3c24xx_led_set;
	led->cdev.default_trigger = pdata->def_trigger;
	led->cdev.name = pdata->name;
	led->cdev.flags |= LED_CORE_SUSPENDRESUME;

	led->pdata = pdata;

	/* no point in having a pull-up if we are always driving */

	if (pdata->flags & S3C24XX_LEDF_TRISTATE) {
		s3c2410_gpio_setpin(pdata->gpio, 0);
		s3c2410_gpio_cfgpin(pdata->gpio, S3C2410_GPIO_INPUT);
	} else {
		s3c2410_gpio_pullup(pdata->gpio, 0);
		s3c2410_gpio_setpin(pdata->gpio, 0);
		s3c2410_gpio_cfgpin(pdata->gpio, S3C2410_GPIO_OUTPUT);
	}

	/* register our new led device */

	ret = led_classdev_register(&dev->dev, &led->cdev);
	if (ret < 0) {
		dev_err(&dev->dev, "led_classdev_register failed\n");
		kfree(led);
		return ret;
	}

	return 0;
}

利用struct，我们实现了一种面向对象的思想，实例化的结构体对象中，有描述这个对象的行为方式（函数），有描述对象特征值或者对象组成的变量（变量，结构体变量等）。

下面是设备结构体定义供参考：

struct platform_driver {
    int (*probe)(struct platform_device *);
    int (*remove)(struct platform_device *);
    void (*shutdown)(struct platform_device *);
    int (*suspend)(struct platform_device *, pm_message_t state);
    int (*resume)(struct platform_device *);
    struct device_driver driver;
    const struct platform_device_id *id_table;
};

/**
 * struct device_driver - The basic device driver structure
 * @name:    Name of the device driver.
 * @bus:    The bus which the device of this driver belongs to.
 * @owner:    The module owner.
 * @mod_name:    Used for built-in modules.
 * @suppress_bind_attrs: Disables bind/unbind via sysfs.
 * @of_match_table: The open firmware table.
 * @probe:    Called to query the existence of a specific device,
 *        whether this driver can work with it, and bind the driver
 *        to a specific device.
 * @remove:    Called when the device is removed from the system to
 *        unbind a device from this driver.
 * @shutdown:    Called at shut-down time to quiesce the device.
 * @suspend:    Called to put the device to sleep mode. Usually to a
 *        low power state.
 * @resume:    Called to bring a device from sleep mode.
 * @groups:    Default attributes that get created by the driver core
 *        automatically.
 * @pm:        Power management operations of the device which matched
 *        this driver.
 * @p:        Driver core‘s private data, no one other than the driver
 *        core can touch this.
 *
 * The device driver-model tracks all of the drivers known to the system.
 * The main reason for this tracking is to enable the driver core to match
 * up drivers with new devices. Once drivers are known objects within the
 * system, however, a number of other things become possible. Device drivers
 * can export information and configuration variables that are independent
 * of any specific device.
 */
struct device_driver {
    const char        *name;
    struct bus_type        *bus;

    struct module        *owner;
    const char        *mod_name;    /* used for built-in modules */

    bool suppress_bind_attrs;    /* disables bind/unbind via sysfs */

    const struct of_device_id    *of_match_table;

    int (*probe) (struct device *dev);
    int (*remove) (struct device *dev);
    void (*shutdown) (struct device *dev);
    int (*suspend) (struct device *dev, pm_message_t state);
    int (*resume) (struct device *dev);
    const struct attribute_group **groups;

    const struct dev_pm_ops *pm;

    struct driver_private *p;
};

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