platform_set_drvdata(struct platform_device *pdev, void *data)
platform_get_drvdata(const struct platform_device *pdev):
驱动中常用到platform_set_drvdata 和 platform_get_drvdata这两个函数,用于保存局部变量:
include/linux/platform_device.h中:
static inline void *platform_get_drvdata(const struct platform_device *pdev)
{ return dev_get_drvdata(&pdev->dev); }
static inline void platform_set_drvdata(struct platform_device *pdev, void *data)
{ dev_set_drvdata(&pdev->dev, data); }
static inline void
dev_set_drvdata (struct device *dev, void *data) { dev->driver_data = data; }
就是吧data赋值给dev->driver_data,pdev是平台总线设备,对于整个驱动是可见的,所以可以通过platform_get_drvdata来获取data。
marvell sd驱动eg:
chip是在probe函数中定义的局部变量,如果想在其他地方使用它怎么办呢? 这就需要把它保存起来。内核提供了这个方法,使用函数platform_set_drvdata()可以将chip保存成平台总线设备的私有
数据。以后再要使用它时只需调用platform_get_drvdata()就可以了。
static int sdhci_mv_probe(struct platform_device *pdev) { struct sdhci_mv_chip *chip; struct sdhci_mv_slot *slot;
chip = kzalloc(sizeof(struct sdhci_mv_chip), GFP_KERNEL);
if (!chip) { ret = -ENOMEM; goto err; }
chip->fixes = (sdhci_mv_get_interface(pdev) == INTERFACE_SDIO0)? &sdhci0_fixes : &sdhci1_fixes;
if (chip->fixes) chip->quirks = chip->fixes->quirks;
platform_set_drvdata(pdev, chip);
} chip是局部变量,在驱动其他函数使用时,eg: static int __devexit sdhci_mv_remove(struct platform_device *pdev) { int i; struct sdhci_mv_chip *chip; chip = platform_get_drvdata(pdev); if (chip) { for (i = 0;i < chip->num_slots; i++) sdhci_mv_remove_slot(chip->slots[i]); platform_set_drvdata(pdev, NULL); kfree(chip); } return 0; }
container_of(ptr,
type, member)
问题:如何通过结构中的某个变量获取结构本身的指针???
container_of(ptr, type, member)宏的作用是 传入结构体类型type的域member的地址ptr,返回该结构体变量的首地址。
member是结构体类型type的成员,ptr是成员member的实例,返回ptr的入口地址;即通过结构体中一个成员的地址来得到此成员所在结构体的地址。
关于container_of见kernel.h中: /** * container_of - cast a member of a structure out to the containing structure * @ptr: the pointer to the member. * @type: the type of the container struct this is embedded in. * @member: the name of the member within the struct. * */ #define container_of(ptr, type, member) ({ / const typeof( ((type *)0)->member ) *__mptr = (ptr); / (type *)( (char *)__mptr - offsetof(type,member) );}) container_of在Linux Kernel中的应用非常广泛,它用于获得某结构中某成员的入口地址.
/* sprd keypad backlight */
struct sprd_lcd_led { struct platform_device *pdev; struct mutex mutex; struct work_structwork; spinlock_t value_lock; enum led_brightness value; struct led_classdev cdev; int enabled; int suspend; struct early_suspend sprd_early_suspend_desc; };
static void led_work(structwork_struct*work)
{ // 传入的参数是结构体类型sprd_lcd_led 的成员work的实例的地址 structsprd_lcd_led*led =container_of(work, struct sprd_lcd_led, work); unsigned long flags; mutex_lock(&led->mutex); spin_lock_irqsave(&led->value_lock, flags); if (led->value == LED_OFF || led->suspend) { spin_unlock_irqrestore(&led->value_lock, flags); sprd_led_disable(led); goto out; } spin_unlock_irqrestore(&led->value_lock, flags); sprd_led_enable(led); out: mutex_unlock(&led->mutex); }
static void sprd_lcd_led_shutdown(structplatform_device*pdev)
{
//传入的参数为platform_device 类型,所以使用platform_get_drvdata()来获取platform_device->device->driver_data
struct sprd_lcd_led*led =platform_get_drvdata(pdev); mutex_lock(&led->mutex); led->value = LED_OFF; led->enabled = 1; sprd_led_disable(led); mutex_unlock(&led->mutex); }
static int sprd_lcd_led_probe(structplatform_device*pdev)
{ struct sprd_lcd_led*led;//局部变量 int ret;
...............................................
led = kzalloc(sizeof(*led), GFP_KERNEL);
platform_set_drvdata(pdev,
led);//局部变量保存到pdev->dev->driver_data (platform_device->device->driver_data)
...............................................
}
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来自: hutashenzhou > 《linux》