【FFH】小熊派驅(qū)動調(diào)用流程（以調(diào)用LED燈驅(qū)動為例）
原創(chuàng)??51CTO和華為官方合作共建的鴻蒙技術(shù)社區(qū)??
??https://harmonyos.51cto.com??
一、流程總覽
驅(qū)動調(diào)用的流程和純代碼開發(fā)的流程十分相似，本文著重點(diǎn)在于驅(qū)動調(diào)用的邏輯。
創(chuàng)建目錄及相應(yīng)源碼文件–>編寫驅(qū)動調(diào)用代碼–>編寫編譯構(gòu)建文件BUILD.gn–>編譯燒錄運(yùn)行
二、源碼目錄結(jié)構(gòu)
在./applications/BearPi/BearPi-HM_Micro/samples/目錄下創(chuàng)建
my_led_app 源碼目錄
*my_led_app.c 驅(qū)動調(diào)用源碼
*BUILD.gn 源碼編譯腳本
如圖所示
三、編寫驅(qū)動調(diào)用代碼
在my_led_app.c中編寫如下代碼
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdio.h>
#include "hdf_sbuf.h"
#include "hdf_io_service_if.h"
#define LED_WRITE_READ 1
#define LED_SERVICE "hdf_led"
static int SendEvent(struct HdfIoService *serv, uint8_t eventData)
{
int ret = 0;
struct HdfSBuf *data = HdfSBufObtainDefaultSize();
if (data == NULL)
{
printf("fail to obtain sbuf data!\r\n");
return 1;
}
struct HdfSBuf *reply = HdfSBufObtainDefaultSize();
if (reply == NULL)
{
printf("fail to obtain sbuf reply!\r\n");
ret = HDF_DEV_ERR_NO_MEMORY;
goto out;
}
/* 寫入數(shù)據(jù) */
if (!HdfSbufWriteUint8(data, eventData))
{
printf("fail to write sbuf!\r\n");
ret = HDF_FAILURE;
goto out;
}
/* 通過Dispatch發(fā)送到驅(qū)動 */
ret = serv->dispatcher->Dispatch(&serv->object, LED_WRITE_READ, data, reply);
if (ret != HDF_SUCCESS)
{
printf("fail to send service call!\r\n");
goto out;
}
int replyData = 0;
/* 讀取驅(qū)動的回復(fù)數(shù)據(jù) */
if (!HdfSbufReadInt32(reply, &replyData))
{
printf("fail to get service call reply!\r\n");
ret = HDF_ERR_INVALID_OBJECT;
goto out;
}
printf("\r\nGet reply is: %d\r\n", replyData);
out:
HdfSBufRecycle(data);
HdfSBufRecycle(reply);
return ret;
}
int main(int argc, char **argv)
{
int i;
/* 獲取服務(wù) */
struct HdfIoService *serv = HdfIoServiceBind(LED_SERVICE);
if (serv == NULL)
{
printf("fail to get service %s!\r\n", LED_SERVICE);
return HDF_FAILURE;
}
for (i=0; i < argc; i++)
{
printf("\r\nArgument %d is %s.\r\n", i, argv[i]);
}
SendEvent(serv, atoi(argv[1]));
HdfIoServiceRecycle(serv);
printf("exit");
return HDF_SUCCESS;
}
這一部分是本文的重點(diǎn)部分
OpenHarmony的設(shè)備開發(fā)中的驅(qū)動調(diào)用與單片機(jī)的驅(qū)動開發(fā)不太相同，以往單片機(jī)的驅(qū)動調(diào)用往往是采用庫函數(shù)調(diào)用的方式，但OpenHarmony的驅(qū)動調(diào)用采用的是驅(qū)動程序暴露出一個server，程序通過Dispatch發(fā)送指令的方式。有點(diǎn)類似與ROS的消息通信機(jī)制中的話題發(fā)布和訂閱。在OpenHarmony中驅(qū)動調(diào)用的這部分程序?qū)儆谟脩舫绦?，是用戶態(tài)的內(nèi)容，而驅(qū)動是內(nèi)核態(tài)的內(nèi)容。所以用戶程序無法直接訪問驅(qū)動，上面代碼通過Dispatch向驅(qū)動程序發(fā)送指令從而實(shí)現(xiàn)LED燈的亮滅。
3.1 發(fā)送指令到驅(qū)動程序
我們看下my_led_app.c中SendEvent函數(shù)中通過Dispatch發(fā)送到驅(qū)動的代碼
/* 通過Dispatch發(fā)送到驅(qū)動 */
ret = serv->dispatcher->Dispatch(&serv->object, LED_WRITE_READ, data, reply);
if (ret != HDF_SUCCESS)
{
printf("fail to send service call!\r\n");
goto out;
}
int replyData = 0;
這段代碼實(shí)現(xiàn)將指令發(fā)送到驅(qū)動程序
驅(qū)動程序指令接受的的代碼在上一篇文章中的led.c驅(qū)動代碼中的LedDriverDispatch函數(shù)
// Dispatch是用來處理用戶態(tài)發(fā)下來的消息
int32_t LedDriverDispatch(struct HdfDeviceIoClient *client, int cmdCode, struct HdfSBuf *data, struct HdfSBuf *reply)
{
uint8_t contrl;
HDF_LOGE("Led driver dispatch");
if (client == NULL || client->device == NULL)
{
HDF_LOGE("Led driver device is NULL");
return HDF_ERR_INVALID_OBJECT;
}
switch (cmdCode)
{
/* 接收到用戶態(tài)發(fā)來的LED_WRITE_READ命令 */
case LED_WRITE_READ:
/* 讀取data里的數(shù)據(jù)，賦值給contrl */
HdfSbufReadUint8(data,&contrl);
switch (contrl)
{
/* 開燈 */
case LED_ON:
GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_LOW);
status = 1;
break;
/* 關(guān)燈 */
case LED_OFF:
GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_HIGH);
status = 0;
break;
/* 狀態(tài)翻轉(zhuǎn) */
case LED_TOGGLE:
if(status == 0)
{
GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_LOW);
status = 1;
}
else
{
GpioWrite(g_Stm32Mp1ILed.gpioNum, GPIO_VAL_HIGH);
status = 0;
}
break;
default:
break;
}
/* 把LED的狀態(tài)值寫入reply, 可被帶至用戶程序 */
if (!HdfSbufWriteInt32(reply, status))
{
HDF_LOGE("replay is fail");
return HDF_FAILURE;
}
break;
default:
break;
}
return HDF_SUCCESS;
}
3.2 從驅(qū)動程序接受數(shù)據(jù)
剛剛實(shí)現(xiàn)了用戶態(tài)向內(nèi)核態(tài)發(fā)送指令，同理，內(nèi)核態(tài)也可以向用戶態(tài)發(fā)送數(shù)據(jù)。
讓我們看看驅(qū)動代碼中向用戶發(fā)送LED狀態(tài)信息的代碼(在led.c中LedDriverDispatch函數(shù)的一部分)
/* 把LED的狀態(tài)值寫入reply, 可被帶至用戶程序 */
if (!HdfSbufWriteInt32(reply, status))
{
HDF_LOGE("replay is fail");
return HDF_FAILURE;
}
下面是用戶程序接收的部分
/* 讀取驅(qū)動的回復(fù)數(shù)據(jù) */
if (!HdfSbufReadInt32(reply, &replyData))
{
printf("fail to get service call reply!\r\n");
ret = HDF_ERR_INVALID_OBJECT;
goto out;
}
printf("\r\nGet reply is: %d\r\n", replyData);
四、編寫編譯構(gòu)建文件BUILD.gn
在BUILD.gn中添加以下代碼
import("http://build/lite/config/component/lite_component.gni")
HDF_FRAMEWORKS = "http://drivers/framework"
executable("led_lib") {
output_name = "my_led"
sources = [
"my_led_app.c",
]
include_dirs = [
"$HDF_FRAMEWORKS/ability/sbuf/include",
"$HDF_FRAMEWORKS/core/shared/include",
"$HDF_FRAMEWORKS/core/host/include",
"$HDF_FRAMEWORKS/core/master/include",
"$HDF_FRAMEWORKS/include/core",
"$HDF_FRAMEWORKS/include/utils",
"$HDF_FRAMEWORKS/utils/include",
"$HDF_FRAMEWORKS/include/osal",
"http://drivers/adapter/uhdf/posix/include",
"http://third_party/bounds_checking_function/include",
"http://base/hiviewdfx/hilog_lite/interfaces/native/innerkits",
]
deps = [
"http://base/hiviewdfx/hilog_lite/frameworks/featured:hilog_shared",
"http://drivers/adapter/uhdf/manager:hdf_core",
"http://drivers/adapter/uhdf/posix:hdf_posix_osal",
]
}
lite_component("my_led_app") {
features = [
":led_lib",
]
}
五、編譯燒錄
參考之前文章Linux下配置小熊派-鴻蒙·叔設(shè)備開發(fā)(南向)的開發(fā)環(huán)境
六、運(yùn)行
串口連接小熊派終端
./bin/my_led 0 #關(guān)閉LED
./bin/my_led 1 #開啟LED
./bin/my_led 2 #翻轉(zhuǎn)LED
??51CTO和華為官方合作共建的鴻蒙技術(shù)社區(qū)??
??https://harmonyos.51cto.com??
