嵌入式Linux驱动开发日记

嵌入式Linux驱动开发日记

主机硬件环境
开发机：虚拟机Ubuntu12.04
内存： 1G
硬盘：80GB

目标板硬件环境
CPU： SP5V210 (开发板：QT210)
SDRAM： 512M  (4片K4T1G164Q )
Nand flash： 512M (K9F4G08)
以太网芯片： SMSC LAN9220

工具介绍
仿真器： 暂无
电缆： 串口线，USB线

Windows 操作系统软件环境
ADS编译工具： 暂无
仿真器软件：暂无
调试软件： 终端（ADB）、eclipse

Linux操作系统软件环境
GNU交叉编译工具： arm-linux-gcc 4.4.1、JDK1.6、git 1.7、gcc 4.5、python 2.7

---

Section ONE：最简单的驱动程序：hello world

---

首先我们写一个最简单的模块。编辑hello_module.c

#include<linux/init.h>    //module_init(),module_exit()
#include<linux/module.h>  //MODULE_AUTHOR(),MODULE_LICENSE()
#include<linux/kernel.h>  //KERN_EMERG

static int hello_init(void){
	printk(KERN_EMERG "hello world enter\n");
	return 0;
}

void hello_exit(void){
	printk(KERN_EMERG "hello world exit\n");
}

module_init(hello_init);
module_exit(hello_exit);

MODULE_AUTHOR("CHSRY");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("A simple Hello World Module");
MODULE_ALIAS("a simplest module");

编写Makefile 

obj-m := hello.o
all:
	make -C /lib/modules/$(shell uname -r)/build SUBDIRS=$(PWD) modules
clean:
	make -C /lib/modules/$(shell uname -r)/build SUBDIRS=$(PWD) clean

运行#make

生成hello.ko，然后使用insmod 命令存入模块：insmod hello.ko

使用lsmod 就能看到你新插入的模块： lsmod | grep hello

使用rmmod移除模块：rmmod hello

最简单的驱动就完成了。

由于Linux内核的级别控制，导致printk打印的内容不一定都能从控制台正常输出

最好的办法是打开另外的一个终端，用一个终端不停地监视并且打印输出当前系统的日志信息：

在终端下输入：

while true
do
    sudo dmesg -c
    sleep 1
done

这样这个终端就会每1秒查看当前系统的日志并清空。

---

Section TWO：LED驱动程序

---

思维导图设计

2.1 QT210 开发板 LED驱动程序和测试程序

驱动文件：hello.c

/************************************************
 LED的驱动，在Real210A开发板上做测试

维护记录：  2011-10-31  V1.0    

linux内核：2.6.35.7

驱动用法：
         设备名称：Real210-led
         点亮一个灯：LED_ON
         熄灭一个灯：LED_OFF
         点亮所有灯：ALL_LED_ON
         熄灭所有灯：ALL_LED_OFF
 *************************************************/
 #include<linux/init.h>
 #include<linux/module.h>

 #include <linux/kernel.h>
 #include <linux/fs.h>
 #include <linux/delay.h>
 #include <asm/irq.h>
 #include <mach/regs-gpio.h>
 #include <mach/hardware.h>
 #include <linux/device.h>
 #include <linux/gpio.h>

 #define DEVICE_NAME    "Real210-led"    /* 设备名称 */
 static int LED_Major = 0;            /* 主设备号 ,系统自动分配*/

 #define LED_OFF             0
 #define LED_ON             1
 #define ALL_LED_OFF      3
 #define ALL_LED_ON       4

/* 用来指定LED所用的GPIO引脚 */
 static unsigned long led_table [] =
 {
     //S5PV210_GPH0(_nr);
     //在头文件“～/kernel/arch/arm/mach-s5pv210/include/mach/”

     S5PV210_GPH0(6),
     S5PV210_GPH0(7),
     S5PV210_GPH0(4),
     S5PV210_GPH0(5),
 };

static int Real210_led_open(struct inode *inode, struct file *file)
 {
 //    MOD_INC_USE_COUNT;
     printk("Real210-LED Driver Open Called!\n");
     return 0;
 }

static int Real210_led_release(struct inode *inode, struct file *file)
 {
 //    MOD_DEC_USE_COUNT;
     printk("Real210-LED Driver Release Called!\n");
     return 0;
 }

static int Real210_led_ioctl( struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
 {
     int i;
     if (arg > 4)
     {
         return -EINVAL;
     }
     switch(cmd)
     {
         case LED_ON:  //set the pin
             gpio_set_value (led_table[arg], 0);
             break;

         case LED_OFF:  //clr the pin
             gpio_set_value (led_table[arg], 1);
             break;

         case ALL_LED_ON:  //set all pin
             for (i = 0; i < 4; i++)
                 gpio_set_value (led_table[i], 0);
             break;

         case ALL_LED_OFF:  //clr all pin
             for (i = 0; i < 4; i++)
                 gpio_set_value (led_table[i], 1);
             break;

         default:
             return -EINVAL;
     }
 }

static struct file_operations Real210_led_fops =
 {
     .owner  =   THIS_MODULE,
     .open   =   Real210_led_open,
     .release =  Real210_led_release,
     .ioctl  =   Real210_led_ioctl,
 };

static struct class *led_class;

static int __init Real210_led_init(void)
 {

    printk("Real210 LED DRIVER MODULE INIT\n");

    LED_Major = register_chrdev(0, DEVICE_NAME, &Real210_led_fops);
     if (LED_Major < 0)
     {
         printk(DEVICE_NAME " can't register major number\n");
         return LED_Major;
     }
     printk("register Real210-LED Driver OK! Major = %d\n", LED_Major);

     led_class = class_create(THIS_MODULE, DEVICE_NAME);
     if(IS_ERR(led_class))
     {
         printk("Err: failed in Real210-LED class. \n");
         return -1;
     }

     device_create(led_class, NULL, MKDEV(LED_Major, 0), NULL, DEVICE_NAME);

     //IO初始化

     //IO方向配置
     gpio_direction_output (S5PV210_GPH0(6), 1);
     gpio_direction_output (S5PV210_GPH0(7), 1);
     gpio_direction_output (S5PV210_GPH0(4), 1);
     gpio_direction_output (S5PV210_GPH0(5), 1);
     //IO初始化
     gpio_set_value (S5PV210_GPH0(6), 1);
     gpio_set_value (S5PV210_GPH0(7), 0); 

     printk(DEVICE_NAME " initialized\n");
     return 0;
 }

static void __exit Real210_led_exit(void)
 {
     printk("Real210 LED DRIVER MODULE EXIT\n");
     unregister_chrdev(LED_Major, DEVICE_NAME);
     device_destroy(led_class, MKDEV(LED_Major, 0));
     class_destroy(led_class);
 }

 module_init(Real210_led_init);
 module_exit(Real210_led_exit);

 //MODULE_LICENSE("Dual BSD/GP");

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("wzl");
 MODULE_DESCRIPTION("This is an example of hello drivers");
 MODULE_ALIAS("A simplest module.");

Makefile文件：

obj-m := hello.o
KDIR := /home/work/QT210/qt210_ics_kernel3.0.8
all:
	make -C $(KDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-eabi-
clean:
	rm -f *.ko *.o *.mod.o *.mod.c *.symvers

测试文件:led.c

 #include<stdio.h>
 #include<stdlib.h>
 #include<unistd.h>
 #include <sys/ioctl.h>

 int main(int argc, char **argv)
 {
     unsigned int on;
     unsigned int led_num;
     int fd;
     printf("Enter the test led !\n");
     fd = open("/dev/Real210-led", 0);
     if (fd < 	0)
     {
         perror("open device led");
         exit(1);
     }

    ioctl(fd, 1, 0);    //可修改本句代码

    close(fd);
     return 0;
 }

Makefile文件：

all: led
led:led.c
     arm-none-linux-gnueabi-gcc -o led led.c -static
     arm-none-linux-gnueabi-strip led
clean:
     @rm -vf led *.o *~

下面是调试信息：

adb shell
#mkdir  mydev
#exit
adb push  d:\android_led.ko    /mydev
adb shell
#cd mydev
#chmod 777 android_led.ko
#insmod android_led.ko
#lsmod  //查看是否加载上了。卸载命令 rmmod  android_led  不要加.ko
# cat /proc/devices   //也可以查看设备号和设备名。
#ls -l /dev/myled     //同样。
此时myled 权限需要修改。
#chmod 777 /dev/myled

2.2 QT210 开发板 LED流水灯 驱动程序

water_led.c的代码

#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/workqueue.h>

static struct delayed_work my_work;

//static int watercount=0;
volatile unsigned long *gph0con = NULL;
volatile unsigned long *gph0dat = NULL;
static void waterfun(void)
{
	static int watercount=0;
	*gph0dat = 0x1 << ((watercount++)%4);//流水灯
	//printk("waterfun:watercount:%d\n",watercount);
	schedule_delayed_work(&my_work,msecs_to_jiffies(1000));
}

static int __init waterinit(void)
{

	int ret;
	gph0con = (volatile unsigned long *)ioremap(0xE0200c00, 16);
	gph0dat = gph0con + 1;
	*gph0con |=0x1111 ;
	*gph0con &=~0xf;
	INIT_DELAYED_WORK(&my_work,waterfun);
	ret = schedule_delayed_work(&my_work,msecs_to_jiffies(1000));
	printk("water init:ret:%d\n",ret);

	return 0;

}
static void __exit waterexit(void)
{
		cancel_delayed_work(&my_work);
		//destroy_wor(my_work);
		//_work(&my_work);
		iounmap(gph0con);

}

module_init(waterinit);
module_exit(waterexit);
MODULE_LICENSE("GPL");

Makefile的代码：

obj-m :=water_led.o

#KDIR :=/home/kernal_driver/linux-tiny6410/
KDIR :=/home/work/QT210/qt210_ics_kernel3.0.8
PWD :=$(shell pwd)
all:
	$(MAKE) -C $(KDIR) M=$(PWD) modules
clean:
	rm -f *.o *.bak *.order *.symvers

可以看到开发板子的 D6 D7 D8呈现流水灯（D5无法控制），证明驱动成功了。

2.3 QT210 开发板 LED驱动程序和android应用程序

目的: 编写一个android应用程序来控制开发板上led灯的亮与灭.

编译环境: Ubuntu12.04

Android系统: android4.0 (linux3.0.8)

一.驱动

1. 查看原理图,QT210开发板上led D5, D6, D7, D8 对应引脚为EINT0, EINT1, EINT2, EINT3.

2. 根据底板上的EINT引脚,在核心板上找到与之相对应的引脚,最终对应到了GPIO的GPH0_0, GPH0_1, GPH0_2, GPH0_3

3.  接下来在三星 S5PV210芯片手册上找到相应寄存器.控制led灯实际就是控制相应寄存器.

S5PV210_EVT1_Usermanual_20100218.pdf

4.  编写驱动文件led.c

#include <linux/module.h>
#include <linux/kernel.h>
//#include <linux/io.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/fs.h>
#include <asm/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/pci.h>
#include <linux/ioctl.h>
#include <linux/init.h>
#include <linux/delay.h> 

#define DEVICE_NAME "leds" //设备名(/dev/leds)
#define LED_MAJOR 240   

unsigned long *gph0con = NULL;
unsigned long *gph0dat = NULL;  

int major;    

static int led_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    printk(KERN_ALERT"\ncmd = %d  arg = %d \n", cmd, arg);
switch(cmd)
    {
case 0:
            printk(KERN_ALERT"led%d off\n", arg);
switch(arg)
            {
case 0:
                                *gph0dat &= ~0x01;
break;
case 1:
                                *gph0dat &= ~0x02;
break;
case 2:
                                *gph0dat &= ~0x04;
break;
case 3:
                                *gph0dat &= ~0x08;
break;
default:
break;
            }
break;
case 1:
            printk(KERN_ALERT"led%d on\n", arg);
switch(arg)
            {
case 0:
                                *gph0dat |= 0x01;
break;
case 1:
                                *gph0dat |= 0x02;
break;
case 2:
                                *gph0dat |= 0x04;
break;
case 3:
                                *gph0dat |= 0x08;
break;
default:
break;
            }    

break;
case 11:
            printk(KERN_ALERT"led all on\n");
                        *gph0dat |= 0xf;
break;
case 10:
            printk(KERN_ALERT"led all off\n");
                        *gph0dat &= ~0xf;
break;
default:
break;
        }    

return 0;
}    

struct file_operations led_fops={
    .owner = THIS_MODULE,
    .unlocked_ioctl = led_ioctl,
};    

static struct miscdevice misc = {
    .minor = MISC_DYNAMIC_MINOR, //动态设备号
    .name = DEVICE_NAME,
    .fops = &led_fops,
};    

static int __init led_init(void)
{
int rc;
        gph0con = (unsigned long *)ioremap(0xE0200C00, 16);
        gph0dat = (unsigned long *)ioremap(0xE0200C04, 8);  

        *gph0con &= ~0xffff;
        *gph0con |= 0x1111;  

        *gph0dat &= ~0xf;  

       rc = misc_register(&misc);    

if(rc<0)
    {
            printk(KERN_ALERT"register %s char dev error\n","leds");
return -1;
    }
else
            printk(KERN_ALERT" lcd module OK!\n");    

return 0;
}    

static void __exit led_exit(void)
{
        unregister_chrdev(LED_MAJOR, "leds");
    printk(KERN_ALERT"module exit\n");
}    

module_init(led_init);
module_exit(led_exit);    

MODULE_LICENSE("GPL");
MODULE_AUTHOR("cw");  

5. 编写led.c的Makefile. 这里将led驱动编译成模块的方式.（注意: 编写Makefile时,行的开头只能用Tab,不能用空格.）

KERNELDIR :=/home/share/210/android4.0/4.0/qt210_ics_kernel3.0.8
PWD :=$(shell pwd)
modules:
    $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
modules_install:
    $(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install
obj-m:=led.o
clean:
    rm -rf *.o *~core .depend .*.cmd *.ko *.mod.c .tmp_versions *.order *.symvers

6. 编译

编译成功后生成led.ko模块.

7. 将led.ko 拷贝到开发板上,半加载.加载之后会在/dev/目录下生成leds这个设备.

二. Android应用程序

1.  新建一个Android应用程序

2. 打开 src/LedActivity.java, 添加public static native int led_ioctl(int i, int j);

添加一个接口是为了利用java来生成jni的头文件.       src/LedActivity.java:

package com.example.led;  

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;  

public class LedActivity extends Activity {  

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_led);
    }  

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.led, menu);
return true;
    }  

public static native int led_ioctl(int i, int j);  

}  

3. 编译整个android项目,将整个Led项目文件拷贝到ubuntu上.

新建一个jni目录

4. 利用java文件自动生成jni头文件.

javah -classpath bin/classes -d jni com.example.led.LedActivity

5. jni目录下编写led.c 即led测试程序led.c.

Led/jni/led.c:

#include <jni.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <android/log.h>  

#define LOG_TAG "LED"       //android logcat
#define  LOGI(...)  __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__    )
#define  LOGE(...)  __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS_    _)  

//int main(int argc, char **argv)
jint JNICALL Java_com_example_led_LedActivity_led_1ioctl(JNIEnv *env, jclass thiz, jint led_nu, jint on)
{
int fd;      

    fd = open("/dev/leds", O_RDWR);
if(fd < 0)
    printf("Can't open /dev/leds!\n");      

    ioctl(fd, on, led_nu);
    LOGI("led_nu=%d,state=%d\n", led_nu, on);
    close(fd);      

return 0;
}  

6.  jni目录下编写Android.mk

Led/jni/Android.mk

LOCAL_PATH := $(call my-dir)  

include $(CLEAR_VARS)
LOCAL_MODULE := Led_ctrl
LOCAL_SRC_FILES := led.c
LOCAL_LDLIBS := -llog
LOCAL_C_INCLUDES := $(MY_ANDROID_SOURCE)/frameworks/base/core/jni/android/graphics \
   $(MY_ANDROID_SOURCE)/external/skia/include/core \
   $(MY_ANDROID_SOURCE)/external/skia/include/images \
   $(MY_ANDROID_SOURCE)/frameworks/base/include \
   $(MY_ANDROID_SOURCE)/system/core/include
include $(BUILD_SHARED_LIBRARY)  

7.  Led目录下运行ndk-bluild, 将led.c文件编译成so库文件.

前提是你已经安装了android-ndk 工具(http://blog.csdn.net/colwer/article/details/8944166)

8.  将生成的libLed_ctrl.so拷贝到eclipse下Led应用程序中的libs/armeabi目录(如果没有armeabi目录需手动创建一个)

9. 在应用程序布局文件中加入4个开关按钮,对应四个led开关,也可以再添加一个总开关来同时控制四个led.

res/layout/activity_led.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".LedActivity" > 

<ToggleButton
android:id="@+id/btn1"
android:layout_width="140dip"
android:layout_height="wrap_content"
android:textOn="led1 on"
android:textOff="led1 off"
android:layout_gravity="center_horizontal"
/>
<ToggleButton
android:id="@+id/btn2"
android:layout_width="140dip"
android:layout_height="wrap_content"
android:textOn="led2 on"
android:textOff="led2 off"
android:layout_gravity="center_horizontal"
/>
<ToggleButton
android:id="@+id/btn3"
android:layout_width="140dip"
android:layout_height="wrap_content"
android:textOn="led3 on"
android:textOff="led3 off"
android:layout_gravity="center_horizontal"
/>
<ToggleButton
android:id="@+id/btn4"
android:layout_width="140dip"
android:layout_height="wrap_content"
android:textOn="led4 on"
android:textOff="led4 off"
android:layout_gravity="center_horizontal"
/> 

</LinearLayout> 

10.  编写java文件.

package com.example.led;  

import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.ToggleButton;  

public class LedActivity extends Activity {  

private static final String TAG = "LED";
private ToggleButton button1;
private ToggleButton button2;
private ToggleButton button3;
private ToggleButton button4;  

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_led);  

        button1 = (ToggleButton)findViewById(R.id.btn1);
        button2 = (ToggleButton)findViewById(R.id.btn2);
        button3 = (ToggleButton)findViewById(R.id.btn3);
        button4 = (ToggleButton)findViewById(R.id.btn4);   

        button1.setOnClickListener(new Button.OnClickListener()
        {
public void onClick(View v)
            {
if (button1.isChecked())
                    led_ioctl(0, 1);    //led1 on
else
                    led_ioctl(0, 0);  //led1 off
            }
        });     

        button2.setOnClickListener(new Button.OnClickListener()
        {
public void onClick(View v)
            {
if (button2.isChecked())
                    led_ioctl(1, 1);  //led2 on
else
                    led_ioctl(1, 0);  //led2 off
            }
        });       

        button3.setOnClickListener(new Button.OnClickListener()
        {
public void onClick(View v)
            {
if (button3.isChecked())
                    led_ioctl(2, 1);  //led3 on
else
                    led_ioctl(2, 0);  //led3 off
            }
        });       

        button4.setOnClickListener(new Button.OnClickListener()
        {
public void onClick(View v)
            {
if (button4.isChecked())
                    led_ioctl(3, 1);  //led4 on
else
                    led_ioctl(3, 0);  //led4 off
            }
        });
    }  

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.led, menu);
return true;
    }  

public static native int led_ioctl(int i, int j);  

static
    {
        System.loadLibrary("Led_ctrl");     //    libs/armeabi/libLed_ctrl.so 

    }  

}  

编译生成Led.apk,并安装到开发板上.

至此,整个工作已经完成,开发板上打开应用程序就可以控制led了.但有几点需要注意

1. 开发板上D5这个灯已经被占用了,所以led1不能控制D5了.

2. 记住运行应用程序前确保内核中led.ko已被加载,并修改 /dev/leds的权限,否则led灯不受控制.

代码下载地址:http://download.csdn.net/detail/colwer/5403281