设备模型元素----
总线
驱动
设备
总线是处理器和设备之间的通道，在设备模型中，所有的设备都通过总线相连，甚至是内部的虚拟总线。（platform）在linux设备模型中，总线由bus_type结构表示，定义在linux/device.h
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;驱动属性
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 dev_pm_ops *pm;
struct bus_type_private *p;
};
总线注册------
bus_register(struct bus_type *bus)
若成功，新的总线将被添加进系统，并可在sysfs的/sys/bus下看到。
总线的删除使用
void bus_unregister(struct bus_type *bus)
总线方法----
int (*match)(struct device *dev,struct device_driver *drv)
当一个新设备或者驱动添加到这个总线时，该方法调用。用于判断指定的驱动程序是否能处理指定的设备。若可以，则返回非零值。
int (*uevent)(struct device *dev,char **envp,int num_envp,char *buffer,int buffer_size)
在为用户空间产生热插拔事件之前，这个方法允许总线添加环境变量。
总线属性------
struct bus_attribute
{
struct attribute attr;
ssize_t (*show)(struct bus_type *,char *buf);
ssize_t (*store)(struct bus_type *,const char *buf,size_t conunt);
}
int bus_create_file(struct bus_type *bus,struct bus_attribute *attr)
创建属性
void bus_remove_file(struct bus_type *bus,struct
bus_attribute *attr)
删除属性
#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>
MODULE_AUTHOR("David Xie");
MODULE_LICENSE("Dual BSD/GPL");
static char *Version = "$Revision: 1.0 $";
static int my_match(struct device *dev, struct device_driver *driver)
{
return !strncmp(dev->bus_id, driver->name, strlen(driver->name));
}
struct bus_type my_bus_type = {
.name = "my_bus",目录名
.match = my_match,
};
static ssize_t show_bus_version(struct bus_type *bus, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%s\n", Version);
}
static BUS_ATTR(version, S_IRUGO, show_bus_version, NULL);
static int __init my_bus_init(void)
{
int ret;
/*注册总线*/
ret = bus_register(&my_bus_type);
if (ret)
return ret;
/*创建属性文件*/
if (bus_create_file(&my_bus_type, &bus_attr_version))
printk(KERN_NOTICE "Fail to create version attribute!\n");
return ret;
}
static void my_bus_exit(void)
{
bus_unregister(&my_bus_type);
}
module_init(my_bus_init);
module_exit(my_bus_exit);
#define BUS_ATTR(_name, _mode, _show, _store) \
struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store)
#define __ATTR(_name,_mode,_show,_store) { \
.attr = {.name = __stringify(_name), .mode = _mode }, \
.show = _show, \
.store = _store, \
}
#define DEVICE_ATTR(_name, _mode, _show, _store) \
struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)
设备描述
struct
device {
struct klist klist_children;
struct klist_node knode_parent; /* node in sibling list */
struct klist_node knode_driver;
struct klist_node knode_bus;
struct device *parent;
struct kobject kobj;
char bus_id[BUS_ID_SIZE]; /* position on parent bus */
在总线上唯一标识该设备的字符串
unsigned uevent_suppress:1;
const char *init_name; /* initial name of the device */
struct device_type *type;
struct semaphore sem; /* semaphore to synchronize calls to
* its driver.
*/
struct bus_type *bus; /* type of bus device is on */
设备所在总线
struct device_driver *driver; /* which driver has allocated this device */
管理该设备的驱动
void *driver_data; /* data private to the driver */
该设备驱动使用的私有数据成员
void *platform_data; /* Platform specific data, device
core doesn't touch it */
struct dev_pm_info power;
#ifdef CONFIG_NUMA
int numa_node; /* NUMA node this device is close to */
#endif
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 */
/* arch specific additions */
struct dev_archdata archdata;
dev_t devt; /* dev_t, creates the sysfs "dev" */
spinlock_t devres_lock;
struct list_head devres_head;
struct klist_node knode_class;
struct class *class;
struct attribute_group **groups; /* optional groups */
void (*release)(struct device *dev);
};
通常的注册和注销函数在
int device_register(struct device *dev);
void device_unregister(struct device *dev);
一条总线也是个设备，也必须按设备注册
sysfs 中的设备入口可有属性. 相关的结构是:
struct device_attribute { struct attribute attr; ssize_t (*show)(struct device *dev, char *buf); ssize_t (*store)(struct device *dev, const char *buf, size_t count); }; 创建 删除属性int device_create_file(struct device *device, struct device_attribute *entry); void device_remove_file(struct device *dev, struct device_attribute *attr);
驱动描述
struct device_driver {
const char *name;驱动程序的名字---体现在sysfs中。
struct bus_type *bus;驱动程序所在的总线struct module *owner;
const char *mod_name; /* used for built-in modules */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);
struct attribute_group **groups;struct dev_pm_ops *pm;
struct driver_private *p;
};调用时机---------int (*probe) (struct device *dev);
当驱动找到与它匹配的设备的时候就会调用。
int driver_register(struct device_driver *drv)
注册驱动
int driver_unregister(struct device_driver *drv)
注销驱动
驱动属性---
struct driver_attribute {
struct attribute attr;
ssize_t (*show)(struct device_driver *driver, char *buf);
ssize_t (*store)(struct device_driver *driver, const char *buf,
size_t count);
};int driver_create_file(struct device_driver *drv,struct driver_attribute *attr)
创建属性
void driver_remove_file(struct device_driver *drv, struct driver_attribute *attr)
删除属性
总结-----
当一个新设备或者驱动添加到这个总线时，该方法调用。用于判断指定的驱动程序是否能处理指定的设备。若可以，则返回非零值。通过设备的bud_id和驱动的名字来匹配。
当驱动找到与它匹配的设备的时候就会调用。