内存文件系统 sys device设备(二)
设备描述结构体
struct device {
...... ...... ...... ...... ...... ......
struct kobject kobj;
char bus_id[BUS_ID_SIZE]; /*在总线上唯一标识该设备的字符串 */
struct bus_type /* 设备所在总线 */
*bus;
struct device_driver *driver; /*管理该设备的驱动*/
void *driver_data;
/*该设备驱动使用的私有数据成员 *
struct klist_node knode_class;
struct class *class;
struct attribute_group
**groups;
void (*release)(struct device *dev);
}
设备注册
1）int device_register(struct device *dev)
注册设备
2）void device_unregister(struct device *dev)
注销设备
**一条总线也是个设备,也必须按设备注册**
设备属性
struct device_attribute
{
struct attribute attr;
ssize_t (*show)(struct device *dev, struct device_attribute
*attr,char *buf);
ssize_t (*store)(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count);
}
1）int device_create_file(struct device *device, struct device_attribute * entry)
创建属性
2）void device_remove_file(struct device * dev, struct device_attribute * attr)
删除属性
bus模块
#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>
MODULE_AUTHOR("cicue");
MODULE_LICENSE("Dual BSD/GPL");
static char *Version = "$Revision: 1.0 $";
/*当一个新设备或者驱动被添加到这个总线时,该方法被调用。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。*/
static int my_match(struct device *dev, struct device_driver *driver)
{
return !strncmp(dev->kobj.name, driver->name, strlen(driver->name));
}
static void my_bus_release(struct device *dev)
{
printk(KERN_DEBUG "my bus release\n");
}
struct device my_bus = {
.kobj.name = "my_bus0",
.release = my_bus_release
};
/*声明总线*/
struct bus_type my_bus_type = {
.name = "my_bus", //总线名字
.match = my_match, //总线match函数指针
};
EXPORT_SYMBOL(my_bus); //导出my_bus
EXPORT_SYMBOL(my_bus_type); //导出my_bus_type
/*
* Export a simple attribute.
*/
static ssize_t show_bus_version(struct bus_type *bus, char *buf)
{
return snprintf(buf, PAGE_SIZE, "%s\n", Version);
}
/*内核代码中如此定义：#define BUS_ATTR(_name, _mode, _show, _store) \
struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store),
它将bus_attr_作为给定的name的前缀来创建总线的真正名称。对应下面的是bus_attr_version*/
static BUS_ATTR(version, S_IRUGO, show_bus_version, NULL);
/*模块加载函数*/
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");
/*注册总线设备*/
ret = device_register(&my_bus);
if (ret)
printk(KERN_NOTICE "Fail to register device:my_bus!\n");
return ret;
}
/*模块卸载函数*/
static void my_bus_exit(void)
{
device_unregister(&my_bus);
bus_unregister(&my_bus_type);
}
module_init(my_bus_init);
module_exit(my_bus_exit);
device模块
#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>
MODULE_AUTHOR("cicue");
MODULE_LICENSE("Dual BSD/GPL");
extern struct device my_bus;
extern struct bus_type my_bus_type;
/* Why need this ?*/
static void my_dev_release(struct device *dev)
{
}
struct device my_dev = {
.init_name = "my_dev",
.bus = &my_bus_type, //指明设备所属的总线
.parent = &my_bus, //该设备的父设备，总线也是一种设备
.release = my_dev_release,
};
static ssize_t mydev_show(struct device *dev,struct device_attribute *attr, char *buf)
{
return sprintf(buf, "%s\n", "This is my device!");
}
static DEVICE_ATTR(dev, S_IRUGO, mydev_show, NULL);
static int __init my_device_init(void)
{
int ret = 0;
/* 初始化设备 */
///strncpy(my_dev->kobj.name, "my_dev", strlen(my_dev->name));
/*注册设备*/
device_register(&my_dev);
/*创建属性文件*/
device_create_file(&my_dev, &dev_attr_dev);
return ret;
}
static void my_device_exit(void)
{
device_unregister(&my_dev);
}
module_init(my_device_init);
module_exit(my_device_exit);
驱动描述结构体
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;
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;
}
1）int driver_register(struct device_driver *drv)
注册驱动
2）void 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 *drv,
char *buf);
ssize_t (*store)(struct device_driver *drv,
const char *buf, size_t count);
}
1）int driver_create_file(struct device_driver * drv, struct driver_attribute * attr)
创建属性
2）void driver_remove_file(struct device_driver * drv, struct driver_attribute * attr)
删除属性
驱动测试函数源码
#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");
extern struct bus_type my_bus_type;
/*当驱动找到对应的设备时会执行该函数*/
static int my_probe(struct device *dev)
{
printk("Driver found device which my driver can handle!\n");
return 0;
}
static int my_remove(struct device *dev)
{
printk("Driver found device unpluged!\n");
return 0;
}
struct device_driver my_driver = {
.name = "my_dev",
.bus = &my_bus_type,
.probe = my_probe,
.remove = my_remove,
};
static ssize_t mydriver_show(struct device_driver *driver, char *buf)
{
return sprintf(buf, "%s\n", "This is my driver!");
}
static DRIVER_ATTR(drv, S_IRUGO, mydriver_show, NULL);
static int __init my_driver_init(void)
{
int ret = 0;
/*注册驱动*/
driver_register(&my_driver);
/*创建属性文件*/
driver_create_file(&my_driver, &driver_attr_drv);
return ret;
}
static void my_driver_exit(void)
{
driver_unregister(&my_driver);
}
module_init(my_driver_init);
module_exit(my_driver_exit);