【打卡】【Linux的设备驱动管理之内核对象】21天学习挑战赛—RK3399平台开发入门到精通-Day16

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续接上篇继续看看Linux的设备驱动管理之内核对象中的bus,devices和driver的结构定义及说明。

1.device

devices的抽象结构为struct device，定义在kernel/include/linux/device.h

struct device {
    /*父设备*/
	struct device		*parent;
    /*该device的私有变量*/
	struct device_private	*p;
    /*该设备对应的kobject*/
	struct kobject kobj;
	const char		*init_name; /* initial name of the device */
	const struct device_type *type;
 
	struct mutex		mutex;	/* mutex to synchronize calls to
					 * its driver.
					 */
    /*该device所需要注册的总线*/
	struct bus_type	*bus;		/* type of bus device is on */
    /*该设备所绑定的驱动*/
	struct device_driver *driver;	/* which driver has allocated this
					   device */
    /*platform模块相关的参数，device-bus-driver模型不关心该变量*/
	void		*platform_data;	/* Platform specific data, device
					   core doesn't touch it */
    /*电源管理相关的内容*/
	struct dev_pm_info	power;
	struct dev_pm_domain	*pm_domain;
    /*引脚配置相关的内容，可实现对该设备关联的引脚进行初始化与设置操作*/
#ifdef CONFIG_PINCTRL
	struct dev_pin_info	*pins;
#endif
    /*numa相关的内容，本次不涉及*/
#ifdef CONFIG_NUMA
	int		numa_node;	/* NUMA node this device is close to */
#endif
    /*以下为dma 相关的内容*/
	u64		*dma_mask;	/* dma mask (if dma'able device) */
	u64		coherent_dma_mask;/* Like dma_mask, but for
					     alloc_coherent mappings as
					     not all hardware supports
					     64 bit addresses for consistent
					     allocations such descriptors. */
 
	struct device_dma_parameters *dma_parms;
 
	struct list_head	dma_pools;	/* dma pools (if dma'ble) */
 
	struct dma_coherent_mem	*dma_mem; /* internal for coherent mem
					     override */
#ifdef CONFIG_CMA
	struct cma *cma_area;		/* contiguous memory area for dma
					   allocations */
#endif
	/* arch specific additions */
	struct dev_archdata	archdata;
    /*该变量主要用于设备树模块使用，该device_node表示dts中的节点信息，当开启OF宏时，driver会根据该device_node
    中的节点名称以及driver中of相关的节点名称，进行device-driver的匹配检测操作，从而支持设备树*/
	struct device_node	*of_node; /* associated device tree node */
	struct acpi_dev_node	acpi_node; /* associated ACPI device node */
 
    /*设备号，当为block/char设备时，需要设置该值，通过该值会实现该设备对应kobject与/sysfs/dev/char 、/sysfs/dev/block
    对应的kobject的链接关联*/
	dev_t			devt;	/* dev_t, creates the sysfs "dev" */
	u32			id;	/* device instance */
 
	spinlock_t		devres_lock;
	struct list_head	devres_head;
 
    /*链接至系统class模块的kset的链表中*/
	struct klist_node	knode_class;
    /*该设备所属的类*/
	struct class		*class;
    /*该设备的默认属性组*/
	const struct attribute_group **groups;	/* optional groups */
    /*release接口，当对该设备进行释放其kobject时，会通过dev_kobj_type的release接口进行device的释放（
    该接口会调用device->release进行device的释放操作）。*/
	void	(*release)(struct device *dev);
	struct iommu_group	*iommu_group;
};

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2.driver

driver的抽象表现形式为struct device_driver，这里所讲的driver即是设备驱动，即device_driver，定义在kernel/include/linux/device.h

struct device_driver {
	const char		*name;/*驱动名称*/
	struct bus_type		*bus;/*该驱动所依附的总线*/
 
    /*该驱动所属module*/
	struct module		*owner;
    /*模块的名称*/
	const char		*mod_name;	/* used for built-in modules */
 
    
	bool suppress_bind_attrs;	/* disables bind/unbind via sysfs */
 
    /*设备树使用的设备id*/
	const struct of_device_id	*of_match_table;
	const struct acpi_device_id	*acpi_match_table;
 
    /*该驱动的探测接口*/
	int (*probe) (struct device *dev);
    /*该驱动的移除接口*/
	int (*remove) (struct device *dev);
    /*shutdown 、suspend、resume主要是对应电源管理方面的接口*/
	void (*shutdown) (struct device *dev);
	int (*suspend) (struct device *dev, pm_message_t state);
	int (*resume) (struct device *dev);
    /*该驱动所相关的属性接口，主要用于与sysfs模块管理*/
	const struct attribute_group **groups;
    /*性能管理相关的内容*/
	const struct dev_pm_ops *pm;
    /*该驱动模块相关的私有变量，主要包括驱动对应的kobject、所属模块的kobject等*/
	struct driver_private *p;
};

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kernel/drivers/base/base.h

struct driver_private {
    /*该驱动对应的kobject*/
	struct kobject kobj;
    /*用于汇聚该驱动所绑定的所有设备*/
	struct klist klist_devices;
    /*用于链接至xxx_bus_type的klist_drivers链表上*/
	struct klist_node knode_bus;
    /*该驱动所属模块的kobject*/
	struct module_kobject *mkobj;
    /*指向本driver_private类型变量所属的driver变量*/
	struct device_driver *driver;
};
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3.bus

bus是Linux上一个很重要的概念，它搭载着devices和drivers且管理着它们。bus的抽象表现为struct bus_type，定义在kernel/include/linux/device.h

struct bus_type {
	/*总线名称*/
	const char		*name;
	/*总线对应设备名称*/
	const char		*dev_name;
	/*该总线对应的device*/
	struct device		*dev_root;
	struct bus_attribute	*bus_attrs;/*总线属性*/
	struct device_attribute	*dev_attrs;/*设备属性*/
	struct driver_attribute	*drv_attrs;/*驱动属性*/
	/*match接口，用于进行device与driver的匹配*/
	int (*match)(struct device *dev, struct device_driver *drv);
	/*uevent接口，用于发送kobject event，供应用层mdev/udev使用*/
	int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
	/*总线的probe接口，该接口会调用具体驱动的probe接口*/
	int (*probe)(struct device *dev);
	/*总线的remove接口，一般该接口主要是调用具体驱动的remove接口*/
	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 dev_pm_ops *pm;/*pm相关*/
 
	struct iommu_ops *iommu_ops;
	/*该接口包含了该bus对应kobject、device对应的kset、driver对应的kset、
	链接所有设备的链表、链接所有驱动的链表等*/
	struct subsys_private *p;
	struct lock_class_key lock_key;
};
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4.class

关于bus,devices和driver描述完后，还有一个重要的概念叫做class.定义在kernel/include/linux/device.h

struct class {
	const char		*name;
	struct module		*owner;
 
    /*该变量定义了该类别默认的属性*/
	struct class_attribute		*class_attrs;
    /*该变量定义了所有属性该类别的设备所定义的默认的属性*/
	struct device_attribute		*dev_attrs;
	struct bin_attribute		*dev_bin_attrs;
    
	struct kobject			*dev_kobj;
    /*事件接口（用于向应用层发送事件如class设备的添加与移除等）*/
	int (*dev_uevent)(struct device *dev, struct kobj_uevent_env *env);
	char *(*devnode)(struct device *dev, umode_t *mode);
    /*释放接口*/
	void (*class_release)(struct class *class);
	void (*dev_release)(struct device *dev);
 
	int (*suspend)(struct device *dev, pm_message_t state);
	int (*resume)(struct device *dev);
 
	const struct kobj_ns_type_operations *ns_type;
	const void *(*namespace)(struct device *dev);
 
	const struct dev_pm_ops *pm;
 
	struct subsys_private *p;
}

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5.基础抽象结构到具体设备的衍生