平台总线(一)

来源:互联网 发布:mac os 两个窗口并排 编辑:程序博客网 时间:2024/03/29 16:57

(注:基于三星S5PV210平台,Linux3.0.8内核)

总线:struct bus_type: 描述一个总线对象,完成匹配

struct bus_type {
const char *name; //要有名字
int (*match)(struct device *dev, struct device_driver *drv);//匹配方法
};
构建/销毁总线:
int bus_register(struct bus_type * bus);
void bus_unregister(struct bus_type *bus);

构建device:描述设备的信息, 比如设备的地址,中断,名字。。。
struct device {
struct kobject kobj; // 继承基类
const char *init_name; //用于匹配的名字
struct bus_type*bus;//存在于哪个总线
void *platform_data; //万能指针
};

注册到总线/移除:
int device_register(struct device *dev)
void device_unregister(struct device *dev)

构建driver:描述设备的驱动代码,比如各种操作设备的方法:ioremap,request_irq...
struct device_driver {
const char *name;//用于匹配的名字
struct bus_type*bus;//存在于哪个总线
int (*probe) (struct device *dev); //匹配之后需要做的事情
int (*remove) (struct device *dev);//device从总线中移除之后做的事情
}
注册和注销:
int driver_register(struct device_driver *drv)

void driver_unregister(struct device_driver *drv)

任务:
1, 构建bus, device, driver
2, 实现匹配方法
3, 实现driver probe


在sys目录下创建文件:/sys/bus/mybus/version

bus_create_file(&mybus,struct bus_attribute * attr)//需要一个struct bus_attribute


可以用以下的宏来构建:


#define __ATTR(_name,_mode,_show,_store) { \
.attr = {.name = __stringify(_name), .mode = _mode },\
.show = _show,\
.store = _store, \
}


#define BUS_ATTR(_name, _mode, _show, _store) \
struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store)


例子:
BUS_ATTR(aaa, 0666, aaa_show, aaa_store);
==>
struct bus_attribute bus_attr_aaa = { 
.attr = {.name = __stringify(aaa), .mode = 0666 },
.show = aaa_show,
.store = aaa_store,
}

#define STR(a)  #a
STR(ruhua250)==> "ruhua250"


/*mybus.c*/

<span style="font-size:14px;">#include <linux/init.h>#include <linux/module.h>#include <linux/device.h>int mybus_match(struct device *dev, struct device_driver *drv){// 成功返回1, 错误返回0if(!strncmp(drv->name, dev->kobj.name, strlen(drv->name))){//表示匹配成功printk("match ok\n");return 1;} else {return 0; //表示匹配不成功}return 0;}struct bus_type mybus = {.name = "mybus",.match = mybus_match,};EXPORT_SYMBOL(mybus);static int __init mybus_init(void){printk("-------^_*  %s-----------\n", __FUNCTION__);//构建一个总线int ret;ret = bus_register(&mybus);if(ret != 0){printk(KERN_ERR "bus_register error\n");return ret;}return 0;}static void __exit mybus_exit(void){printk("-------^_*%s-----------\n", __FUNCTION__);bus_unregister(&mybus);}module_init(mybus_init);module_exit(mybus_exit);MODULE_LICENSE("GPL");</span>
</pre><pre name="code" class="cpp"><span style="font-size:14px;">/* mydevice.c */#include <linux/init.h>#include <linux/module.h>#include <linux/device.h>extern struct bus_type mybus;void  mydevice_release(struct device *dev){printk(KERN_INFO "\n------*_^%s--------\n",__func__);}struct device mydevice = {.init_name = "mydevice",  /* initial name of the device */.bus = &mybus,/* type of bus device is on */.release = mydevice_release};static int __init mydevice_init(void){int ret;/*1.构建一个device 并且注册到总线*/ret = device_register(&mydevice);if (ret < 0) {printk(KERN_ERR "device_register fail\n");return ret;}printk(KERN_INFO "\n------*_^%s--------\n",__func__);return 0;}static void __exit mydevice_exit(void){/*注销device 并且注册到总线*/device_unregister(&mydevice);printk(KERN_INFO "\n------*_^%s--------\n",__func__);}module_init(mydevice_init);module_exit(mydevice_exit);MODULE_LICENSE("GPL");</span>
</pre><pre name="code" class="cpp"><span style="font-size:14px;">/* mydriver.c */#include <linux/init.h>#include <linux/module.h>#include <linux/device.h>extern struct bus_type mybus;int mydrv_probe(struct device *dev){printk(KERN_INFO "\n------*_^%s--------\n",__func__);return 0;}int mydrv_remove(struct device *dev){printk(KERN_INFO "\n------*_^%s--------\n",__func__);return 0;}struct device_driver mydriver = {.name = "mydriver",.bus = &mybus,.probe = mydrv_probe,.remove = mydrv_remove};static int __init mydriver_init(void){int ret;/*1.构建一个driver并且注册到总线*/ret = driver_register(&mydriver);if (ret < 0) {printk(KERN_ERR "driver_register fail \n");return ret;}printk(KERN_INFO "\n------*_^%s--------\n",__func__);return 0;}static void __exit mydriver_exit(void){/*注销driver*/driver_unregister(&mydriver);printk(KERN_INFO "\n------*_^%s--------\n",__func__);}module_init(mydriver_init);module_exit(mydriver_exit);MODULE_LICENSE("GPL");</span>


/*Makefile*/
<span style="font-size:14px;">ROOTFS_DIR = /opt/filesystemMODULE_NAME = mybusMODULE_NAME2 = mydriverMODULE_NAME3 = mydeviceifeq ($(KERNELRELEASE), )KERNEL_DIR = /home/linux-3.0.8CUR_DIR = $(shell pwd)all :make -C $(KERNEL_DIR) M=$(CUR_DIR) modulesclean :make -C $(KERNEL_DIR) M=$(CUR_DIR) cleaninstall:cp -raf *.ko   $(ROOTFS_DIR)/drv_moduleelseobj-m = $(MODULE_NAME).oobj-m += $(MODULE_NAME2).oobj-m += $(MODULE_NAME3).oendif</span>
0 0
原创粉丝点击