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一、前言

以STM32為例，打開網(wǎng)絡(luò)上下載的例程或者是購(gòu)買開發(fā)板自帶的例程，都會(huì)發(fā)現(xiàn)應(yīng)用層中會(huì)有stm32f10x.h或者stm32f10x_gpio.h，這些文件嚴(yán)格來時(shí)屬于硬件層的，如果軟件層出現(xiàn)這些文件會(huì)顯得很亂。

使用過Linux的童鞋們肯定知道linux系統(tǒng)無法直接操作硬件層，打開linux或者rt_thread代碼會(huì)發(fā)現(xiàn)代碼中都會(huì)有device的源文件，沒錯(cuò)，這就是驅(qū)動(dòng)層。

(相關(guān)資料圖)

二、實(shí)現(xiàn)原理

原理就是將硬件操作的接口全都放到驅(qū)動(dòng)鏈表上，在驅(qū)動(dòng)層實(shí)現(xiàn)device的open、read、write等操作。當(dāng)然這樣做也有弊端，就是驅(qū)動(dòng)find的時(shí)候需要遍歷一遍驅(qū)動(dòng)鏈表，這樣會(huì)增加代碼運(yùn)行時(shí)間。

三、代碼實(shí)現(xiàn)

國(guó)際慣例，寫代碼先寫頭文件。rt_thread中使用的是雙向鏈表，為了簡(jiǎn)單在這我只用單向鏈表。有興趣的可以自行研究rt_thread

頭文件接口:

本次只實(shí)現(xiàn)如下接口，device_open 和device_close等剩下的接口可以自行研究。這樣就可以在應(yīng)用層中只調(diào)用如下接口可實(shí)現(xiàn)：

/*驅(qū)動(dòng)注冊(cè)*/intcola_device_register(cola_device_t*dev);/*驅(qū)動(dòng)查找*/cola_device_t*cola_device_find(constchar*name);/*驅(qū)動(dòng)讀*/intcola_device_read(cola_device_t*dev,intpos,void*buffer,intsize);/*驅(qū)動(dòng)寫*/intcola_device_write(cola_device_t*dev,intpos,constvoid*buffer,intsize);/*驅(qū)動(dòng)控制*/intcola_device_ctrl(cola_device_t*dev,intcmd,void*arg);;

頭文件cola_device.h：

#ifndef_COLA_DEVICE_H_#define_COLA_DEVICE_H_enumLED_state{LED_OFF,LED_ON,LED_TOGGLE,};typedefstructcola_devicecola_device_t;structcola_device_ops{int(*init)(cola_device_t*dev);int(*open)(cola_device_t*dev,intoflag);int(*close)(cola_device_t*dev);int(*read)(cola_device_t*dev,intpos,void*buffer,intsize);int(*write)(cola_device_t*dev,intpos,constvoid*buffer,intsize);int(*control)(cola_device_t*dev,intcmd,void*args);};structcola_device{constchar*name;structcola_device_ops*dops;structcola_device*next;};/*驅(qū)動(dòng)注冊(cè)*/intcola_device_register(cola_device_t*dev);/*驅(qū)動(dòng)查找*/cola_device_t*cola_device_find(constchar*name);/*驅(qū)動(dòng)讀*/intcola_device_read(cola_device_t*dev,intpos,void*buffer,intsize);/*驅(qū)動(dòng)寫*/intcola_device_write(cola_device_t*dev,intpos,constvoid*buffer,intsize);/*驅(qū)動(dòng)控制*/intcola_device_ctrl(cola_device_t*dev,intcmd,void*arg);#endif

源文件cola_device.c：

#include"cola_device.h"#include#includestructcola_device*device_list=NULL;/*查找任務(wù)是否存在*/staticboolcola_device_is_exists(cola_device_t*dev){cola_device_t*cur=device_list;while(cur!=NULL){if(strcmp(cur->name,dev->name)==0){returntrue;}cur=cur->next;}returnfalse;}staticintdevice_list_inster(cola_device_t*dev){cola_device_t*cur=device_list;if(NULL==device_list){device_list=dev;dev->next=NULL;}else{while(NULL!=cur->next){cur=cur->next;}cur->next=dev;dev->next=NULL;}return1;}/*驅(qū)動(dòng)注冊(cè)*/intcola_device_register(cola_device_t*dev){if((NULL==dev)||(cola_device_is_exists(dev))){return0;}if((NULL==dev->name)||(NULL==dev->dops)){return0;}returndevice_list_inster(dev);}/*驅(qū)動(dòng)查找*/cola_device_t*cola_device_find(constchar*name){cola_device_t*cur=device_list;while(cur!=NULL){if(strcmp(cur->name,name)==0){returncur;}cur=cur->next;}returnNULL;}/*驅(qū)動(dòng)讀*/intcola_device_read(cola_device_t*dev,intpos,void*buffer,intsize){if(dev){if(dev->dops->read){returndev->dops->read(dev,pos,buffer,size);}}return0;}/*驅(qū)動(dòng)寫*/intcola_device_write(cola_device_t*dev,intpos,constvoid*buffer,intsize){if(dev){if(dev->dops->write){returndev->dops->write(dev,pos,buffer,size);}}return0;}/*驅(qū)動(dòng)控制*/intcola_device_ctrl(cola_device_t*dev,intcmd,void*arg){if(dev){if(dev->dops->control){returndev->dops->control(dev,cmd,arg);}}return0;}

硬件注冊(cè)方式:以LED為例，初始化接口void led_register(void)，需要在初始化中調(diào)用。

#include"stm32f0xx.h"#include"led.h"#include"cola_device.h"#definePORT_GREEN_LEDGPIOC#definePIN_GREENLEDGPIO_Pin_13/*LED亮、滅、變化*/#defineLED_GREEN_OFF(PORT_GREEN_LED->BSRR=PIN_GREENLED)#defineLED_GREEN_ON(PORT_GREEN_LED->BRR=PIN_GREENLED)#defineLED_GREEN_TOGGLE(PORT_GREEN_LED->ODR^=PIN_GREENLED)staticcola_device_tled_dev;staticvoidled_gpio_init(void){GPIO_InitTypeDefGPIO_InitStructure;RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOC,ENABLE);GPIO_InitStructure.GPIO_Pin=PIN_GREENLED;GPIO_InitStructure.GPIO_Mode=GPIO_Mode_OUT;GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;GPIO_InitStructure.GPIO_OType=GPIO_OType_PP;GPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_NOPULL;GPIO_Init(PORT_GREEN_LED,&GPIO_InitStructure);LED_GREEN_OFF;}staticintled_ctrl(cola_device_t*dev,intcmd,void*args){if(LED_TOGGLE==cmd){LED_GREEN_TOGGLE;}else{}return1;}staticstructcola_device_opsops={.control=led_ctrl,};voidled_register(void){led_gpio_init();led_dev.dops=&ops;led_dev.name="led";cola_device_register(&led_dev);}

應(yīng)用層app代碼:

#include#include"app.h"#include"config.h"#include"cola_device.h"#include"cola_os.h"statictask_ttimer_500ms;staticcola_device_t*app_led_dev;//led每500ms狀態(tài)改變一次staticvoidtimer_500ms_cb(uint32_tevent){cola_device_ctrl(app_led_dev,LED_TOGGLE,0);}voidapp_init(void){app_led_dev=cola_device_find("led");assert(app_led_dev);cola_timer_create(&timer_500ms,timer_500ms_cb);cola_timer_start(&timer_500ms,TIMER_ALWAYS,500);}

這樣app.c文件中就不需要調(diào)用led.h頭文件了，rtt就是這樣實(shí)現(xiàn)的。

四、總結(jié)

這樣就可以實(shí)現(xiàn)軟硬件分層了，是不是非常好用！