Linux内核模块和Linux fs 与 sysfs 二

主要参考整理《Linux设备驱动开发详解》

2. kobject 内核对象----设备模型的核心部分：

    kobject 结构体： 间： /linux/include/linux/kobject.h

struct kobject {const char*name; //对象名称struct krefkref; //对象引用计数struct list_headentry; //用于将kobject 挂接到kset链表struct kobject*parent; //指向kobject的父指针struct kset*kset; //指向kset的指针struct kobj_type*ktype; //指向kobject 的类型struct sysfs_dirent*sd;unsigned int state_initialized:1;unsigned int state_in_sysfs:1;unsigned int state_add_uevent_sent:1;unsigned int state_remove_uevent_sent:1;};

   

    kobj_type 结构体：

   struct kobj_type {void (*release)(struct kobject *kobj); //release 释放函数struct sysfs_ops *sysfs_ops; //sysfs 属性操作struct attribute **default_attrs; //默认的属性}

  

    sys_ops 结构体 ：

     struct kobj_attribute {struct attribute attr; //属性ssize_t (*show)(struct kobject *kobj, struct kobj_attribute *attr,char *buf); //显示属性ssize_t (*store)(struct kobject *kobj, struct kobj_attribute *attr, const char *buf, size_t count); //保存属性}

   操作 kobject 的函数 ：

   初始化kobject：

                void kobject_init(struct kobject *kobj, struct kobj_type *ktype)；

   设置kobject 的名称：

                int kobject_set_name(struct kobject *kobj, const char *name, ...)
       __attribute__((format(printf, 2, 3)))；

   清除 kobject :

                 void kobject_del(struct kobject *kobj);

  。。。。。。。。。

   具体的操作可以在使用的时候参考。

 

3. kset 结构体 ： kset 是具有相同类型的kobject的集合，其结构体如下：

struct kset {struct list_head list; //用于链接该kset中所有kobject 的链表头spinlock_t list_lock; //struct kobject kobj; //链接的kobject 个体struct kset_uevent_ops *uevent_ops; //事件操作}

    注： 形象地来说： kset 类似于一个具有相同属性的链表集合，kobject  则是一个个单独的个体；而当koject 进入链表或者退出链表是会产生一些事件（kset_uevent_ops）

    kset_uevent_ops 结构体；

struct kset_uevent_ops {int (*filter)(struct kset *kset, struct kobject *kobj); //用于过滤一些事件 const char *(*name)(struct kset *kset, struct kobject *kobj); //int (*uevent)(struct kset *kset, struct kobject *kobj, struct kobj_uevent_env *env);}； //环境变量的设置

 

  4. subsystem内核对象子系统： subsystem是一系列kset的集合，描述系统中某一类设备子系统。

 

  5. Linux设备模型组件：

           1） 系统中的任一设备在设备模型（udev）中都是通过一个 device 对象描述，其结构如下：

struct device {struct klistklist_children; //设备列表中的孩子列表struct klist_nodeknode_parent;/* node in sibling list */struct klist_nodeknode_driver; //驱动节点struct klist_nodeknode_bus; //总线节点struct device*parent; //父指针struct kobject kobj;charbus_id[BUS_ID_SIZE];/* position on parent bus */struct device_type*type;unsigneduevent_suppress:1;struct semaphoresem;/* semaphore to synchronize calls to * its driver. */struct bus_type*bus;/* type of bus device is on */struct device_driver *driver;/* which driver has allocated this device */void*driver_data;/* data private to the driver */void*platform_data;/* Platform specific data, device core doesn't touch it */struct dev_pm_infopower;#ifdef CONFIG_NUMAintnuma_node;/* NUMA node this device is close to */#endifu64*dma_mask;/* dma mask (if dma'able device) */u64coherent_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_headdma_pools;/* dma pools (if dma'ble) */struct dma_coherent_mem*dma_mem; /* internal for coherent mem override *//* arch specific additions */struct dev_archdataarchdata;spinlock_tdevres_lock;struct list_headdevres_head;struct list_headnode;struct class*class;dev_tdevt;/* dev_t, creates the sysfs "dev" */struct attribute_group**groups;/* optional groups */void(*release)(struct device *dev);}

       device描述了系统中设备的相关信息以及相互间的关系，以及使用到的总线和使用到得驱动程序。

       Linux中还提供了一些操作device设备的方法：
extern int __must_check device_register(struct device *dev);
extern void device_unregister(struct device *dev);
extern void device_initialize(struct device *dev);
extern int __must_check device_add(struct device *dev);
extern void device_del(struct device *dev);
extern int device_for_each_child(struct device *dev, void *data,
       int (*fn)(struct device *dev, void *data));
extern struct device *device_find_child(struct device *dev, void *data,
    int (*match)(struct device *dev, void *data));
extern int device_rename(struct device *dev, char *new_name);
extern int device_move(struct device *dev, struct device *new_parent);

  注意： 在linux中， device结构体一般不会单独使用，而是结合device使用： 例如在wm8350中 见：linux/include/linux/mfs/wm8350/core.h

 struct wm8350 {int rev;/* chip revision */struct device *dev; //device 结构体/* device IO */union {struct i2c_client *i2c_client;struct spi_device *spi_device;};int (*read_dev)(struct wm8350 *wm8350, char reg, int size, void *dest);int (*write_dev)(struct wm8350 *wm8350, char reg, int size, void *src);u16 *reg_cache;/* Interrupt handling */struct work_struct irq_work;struct mutex irq_mutex; /* IRQ table mutex */struct wm8350_irq irq[WM8350_NUM_IRQ];int chip_irq;/* Client devices */struct wm8350_codec codec;struct wm8350_gpio gpio; struct wm8350_hwmon hwmon;struct wm8350_pmic pmic;struct wm8350_power power;struct wm8350_rtc rtc;struct wm8350_wdt wdt;}

  

    2）系统中的每个驱动程序都有一个device_driver对象描述：

struct device_driver {const char*name; //设备驱动程序的名称struct bus_type*bus; //总线struct module*owner;const char *mod_name;/* used for built-in modules */int (*probe) (struct device *dev); //设备的探测函数int (*remove) (struct device *dev);void (*shutdown) (struct device *dev);int (*suspend) (struct device *dev, pm_message_t state);int (*resume) (struct device *dev);struct attribute_group **groups;struct driver_private *p;}

 

       3） 系统中的总线用 struct bus_type 表示

 struct bus_type {const char*name; //总线名称struct bus_attribute*bus_attrs; //总线属性struct device_attribute*dev_attrs; //设备属性struct driver_attribute*drv_attrs; //设备驱动程序属性int (*match)(struct device *dev, struct device_driver *drv);int (*uevent)(struct device *dev, struct kobj_uevent_env *env);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 (*suspend_late)(struct device *dev, pm_message_t state);int (*resume_early)(struct device *dev);int (*resume)(struct device *dev);struct bus_type_private *p;}

 

      4） 系统中的设备类用 struct class ,表示某一类设备。

       struct class {const char*name; //类名struct module*owner;struct ksetsubsys; //struct list_headdevices; //class_device 链表struct list_headinterfaces; // class_interface 链表struct ksetclass_dirs;struct semaphoresem; /* locks children, devices, interfaces */struct class_attribute*class_attrs; //类属性struct device_attribute*dev_attrs; //设备属性int (*dev_uevent)(struct device *dev, struct kobj_uevent_env *env); //事件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);};

        5)  设备类的驱动程序： struct class_device :

        6)  当发生设备加入或者删除时会调用 class_interface 的成员函数：

            struct class_interface {struct list_headnode;struct class*class;int (*add_dev)(struct device *, struct class_interface *);void (*remove_dev)(struct device *, struct class_interface *);};

       7） 属性：