如何實現(xiàn)嵌入式軟硬件分層處理接口？

工程師進階筆記 · 發(fā)表于 2024-8-12 17:50:00

我是老溫，一名熱愛學習的嵌入式工程師
關注我，一起變得更加優(yōu)秀！一、前言以STM32為例，打開網(wǎng)絡上下載的例程或者是購買開發(fā)板自帶的例程，都會發(fā)現(xiàn)應用層中會有stm32f10x.h或者stm32f10x_gpio.h，這些文件嚴格來時屬于硬件層的，如果軟件層出現(xiàn)這些文件會顯得很亂。
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代碼會發(fā)現(xiàn)代碼中都會有device的源文件，沒錯，這就是驅動層。

二、實現(xiàn)原理原理就是將硬件操作的接口全都放到驅動鏈表上，在驅動層實現(xiàn)device的open、read、write等操作。當然這樣做也有弊端，就是驅動find的時候需要遍歷一遍驅動鏈表，這樣會增加代碼運行時間。
三、代碼實現(xiàn)國際慣例，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。這樣就可以在應用層中只調用如下接口可實現(xiàn)：
/*
驅動注冊
*/
int cola_device_register(cola_device_t *dev);
/*
驅動查找
*/
cola_device_t *cola_device_find(const char *name);
/*
驅動讀
*/
int cola_device_read(cola_device_t *dev,  int pos, void *buffer, int size);
/*
驅動寫
*/
int cola_device_write(cola_device_t *dev, int pos, const void *buffer, int size);
/*
驅動控制
*/
int cola_device_ctrl(cola_device_t *dev,  int cmd, void *arg);;頭文件cola_device.h：
#ifndef _COLA_DEVICE_H_
#define _COLA_DEVICE_H_
enum LED_state
{
LED_OFF,
LED_ON,
LED_TOGGLE,
};
typedef struct cola_device  cola_device_t;
struct cola_device_ops
{
int(*init)(cola_device_t*dev);
int(*open)(cola_device_t*dev,int oflag);
int(*close)(cola_device_t*dev);
int(*read)(cola_device_t*dev,int pos,void*buffer,int size);
int(*write)(cola_device_t*dev,int pos,constvoid*buffer,int size);
int(*control)(cola_device_t*dev,int cmd,void*args);
};
struct cola_device
{
const char* name;
struct cola_device_ops *dops;
struct cola_device *next;
};
/*
驅動注冊
*/
int cola_device_register(cola_device_t *dev);
/*
驅動查找
*/
cola_device_t *cola_device_find(const char *name);
/*
驅動讀
*/
int cola_device_read(cola_device_t *dev,  int pos, void *buffer, int size);
/*
驅動寫
*/
int cola_device_write(cola_device_t *dev, int pos, const void *buffer, int size);
/*
驅動控制
*/
int cola_device_ctrl(cola_device_t *dev,  int cmd, void *arg);
#endif 源文件cola_device.c：
#include "cola_device.h"
#include
#include
struct cola_device *device_list = NULL;
/*
查找任務是否存在
*/
static bool cola_device_is_exists( cola_device_t *dev )
{
cola_device_t* cur = device_list;
while( cur !=NULL)
{
      if(strcmp(cur->name,dev->name)==0)
      {
         return true;
      }
      cur = cur->next;
}
return false;
}
static int device_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;
}
return 1;
}
/*
驅動注冊
*/
int cola_device_register(cola_device_t *dev)
{
if((NULL== dev)||(cola_device_is_exists(dev)))
{
      return 0;
}
if((NULL== dev->name)||(NULL== dev->dops))
{
      return 0;
}
return device_list_inster(dev);
}
/*
驅動查找
*/
cola_device_t *cola_device_find(const char *name)
{
cola_device_t* cur = device_list;
while( cur !=NULL)
{
      if(strcmp(cur->name,name)==0)
      {
         return cur;
      }
      cur = cur->next;
}
return NULL;
}
/*
驅動讀
*/
int cola_device_read(cola_device_t *dev,  int pos, void *buffer, int size)
{
if(dev)
{
      if(dev->dops->read)
      {
         return dev->dops->read(dev, pos, buffer, size);
      }
}
return 0;
}
/*
驅動寫
*/
int cola_device_write(cola_device_t *dev, int pos, const void *buffer, int size)
{
if(dev)
{
      if(dev->dops->write)
      {
         return dev->dops->write(dev, pos, buffer, size);
      }
}
return 0;
}
/*
驅動控制
*/
int cola_device_ctrl(cola_device_t *dev,  int cmd, void *arg)
{
if(dev)
{
      if(dev->dops->control)
      {
         return dev->dops->control(dev, cmd, arg);
      }
}
return 0;
}硬件注冊方式:以LED為例，初始化接口void led_register(void)，需要在初始化中調用。
#include "stm32f0xx.h"
#include "led.h"
#include "cola_device.h"
#define PORT_GREEN_LED                GPIOC
#define PIN_GREENLED                GPIO_Pin_13
/* LED亮、滅、變化 */
#define LED_GREEN_OFF                (PORT_GREEN_LED->BSRR = PIN_GREENLED)
#define LED_GREEN_ON                (PORT_GREEN_LED->BRR  = PIN_GREENLED)
#define LED_GREEN_TOGGLE             (PORT_GREEN_LED->ODR ^= PIN_GREENLED)
static cola_device_t led_dev;
static void led_gpio_init(void)
{
GPIO_InitTypeDef GPIO_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;
}

static int led_ctrl(cola_device_t *dev, int cmd, void *args)
{
if(LED_TOGGLE == cmd)
{
      LED_GREEN_TOGGLE;
}
else
{
}
return 1;
}
static struct cola_device_ops ops =
{
.control = led_ctrl,
};
void led_register(void)
{
led_gpio_init();
led_dev.dops =&ops;
led_dev.name ="led";
cola_device_register(&led_dev);
}應用層app代碼:
#include
#include "app.h"
#include "config.h"
#include "cola_device.h"
#include "cola_os.h"
static task_t timer_500ms;
static cola_device_t*app_led_dev;
//led每500ms狀態(tài)改變一次
static void timer_500ms_cb(uint32_t event)
{
cola_device_ctrl(app_led_dev,LED_TOGGLE,0);
}
void app_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文件中就不需要調用led.h頭文件了，rtt就是這樣實現(xiàn)的。
四、代碼下載鏈接https://gitee.com/schuck/cola_os
' R/ x9 n- c1 u/ P, C- o原文鏈接：https://blog.csdn.net/ziqi5543/article/details/101512722
-END-
往期推薦：點擊圖片即可跳轉閱讀