linux device model
Linux设备模型是一个很大的概念，这里就借着这篇(pdf)[https://bootlin.com/pub/conferences/2019/elce/opdenacker-kernel-programming-device-model/opdenacker-kernel-programming-device-model.pdf]稍微介绍一下。
主要的数据结构
bus_type
主要的数据结构涉及三类： struct bus_type,which was defined in include/linux/device.h.这个结构体就是定义了设备的bus类型,包括USB、PCI、I2C等总线类型。
实例化这个结构体,就代表了其中的一种协议。
struct bus_type {
const char *name;
const char *dev_name;
struct device *dev_root;
const struct attribute_group **bus_groups;
const struct attribute_group **dev_groups;
const struct attribute_group **drv_groups;
int (*match)(struct device *dev, struct device_driver *drv);
int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
int (*probe)(struct device *dev);
void (*sync_state)(struct device *dev);
int (*remove)(struct device *dev);
void (*shutdown)(struct device *dev);
int (*online)(struct device *dev);
int (*offline)(struct device *dev);
int (*suspend)(struct device *dev, pm_message_t state);
int (*resume)(struct device *dev);
int (*num_vf)(struct device *dev);
int (*dma_configure)(struct device *dev);
const struct dev_pm_ops *pm;
const struct iommu_ops *iommu_ops;
...
}
device_driver
该结构体同样定义在上述头文件中，代表了在某一种总线上控制的一种特定设备。
struct device_driver {
const char *name;
struct bus_type *bus; //继承上面的一种类型
struct module *owner;
const char *mod_name; /* used for built-in modules */
bool suppress_bind_attrs; /* disables bind/unbind via sysfs */
enum probe_type probe_type;
const struct of_device_id *of_match_table;
const struct acpi_device_id *acpi_match_table;
int (*probe) (struct device *dev);
void (*sync_state)(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 attribute_group **dev_groups;
const struct dev_pm_ops *pm;
void (*coredump) (struct device *dev);
struct driver_private *p;
};
device
该结构体同样在上述头文件中，代表了一个连接到总线的设备。根据内核的注释，这里有一个问题就是在linux的设备模型中，kobject代表了一个很重要的含义。
struct device {
struct kobject kobj;
struct device *parent;
struct device_private *p;
const char *init_name; /* initial name of the device */
const struct device_type *type;
struct bus_type *bus; /* type of bus device is on */
struct device_driver *driver; /* which driver has allocated this
device */
void *platform_data; /* Platform specific data, device