Android驱动例子(LED灯控制)

原文地址:http://www.linuxidc.com/Linux/2011-04/34541.htm

 

本例子,讲述在android2.1上完全自已开发一个驱动去控制硬件口并写应用测试该驱动,通过这样一个例子,解析android下的驱动开发流程的应用调用流程,可以说是很好的入门引导

要达到的效果:通过android的应用,调用驱动程序,在开发板上控制4个LED的亮灭。

一、硬件原理

clip_image001

如上图,通过4个IO口控制这LED,低电平LED亮,

这4个IO口分别是GPM1, GPM2, GPM3, GPM4,

二、驱动程序

1、在kernel文件夹下的driver目录,新键驱动文件夹

# cd kernel_android_2.6.28.6/drivers

进到开发板的kernel目录,建驱动文件夹

#mkdir ledtest

2、在/driver/ledtest目录下,新建leddriver.c ,leddriver.h , Kconfig, Makefile 等4个文件

leddriver.c

leddriver.c
  1. #include <linux/kernel.h>
  2. #include <linux/sched.h>
  3. #include <linux/timer.h>
  4. #include <linux/init.h>            /* For __init/__exit/... */
  5. #include <linux/module.h>
  6. #include <mach/hardware.h>
  7. #include <asm/io.h>
  8. #include <asm/uaccess.h>
  9. #include <plat/gpio-cfg.h>
  10. #include <plat/regs-clock.h>
  11. #include <plat/regs-lcd.h>
  12. #include <plat/regs-gpio.h>
  13. #include <mach/map.h>
  14. #include <linux/gpio.h>
  15. #include <plat/gpio-bank-m.h>
  16. #include <linux/cdev.h>
  17. #include <linux/fs.h> //for register_chrdev()
  18. #include <linux/device.h>
  19. #include <mach/map.h>
  20. #include "leddriver.h"
  21. #include <linux/miscdevice.h>        /* For MODULE_ALIAS_MISCDEV
  22.                             (WATCHDOG_MINOR) */
  23. #include <linux/watchdog.h>        /* For the watchdog specific items */
  24. #include <linux/fs.h>            /* For file operations */
  25. #define Viberator_MAJOR        97  //?÷éè±?o?
  26. #define SCULL_NR_DEVS           4
  27. #define SCULL_QUANTUM         4000
  28. #define SCULL_QSET             1000
  29. //---do as the GIO driver
  30. #define DEVCOUNT                4
  31. #define GIO_MINOR            2    /* GIO minor no. */
  32. static dev_t dev;        //éê ?? μ?μ??÷ éè±? o?
  33. static struct cdev *cdev_p;
  34. static int openCnt;
  35. //--è???±?á?------------
  36. int VIB_major  = 97;//we asigment it for test
  37. int VIB_minor = 0;
  38. int VIB_nr_devs = SCULL_NR_DEVS;
  39. int VIB_quantum = SCULL_QUANTUM;
  40. int VIB_qset = SCULL_QSET;
  41.  
  42. static struct class *vib_dev_class;
  43. #define GPNCON  S3C64XX_GPNCON
  44. #define GPNDAT  S3C64XX_GPNDAT
  45. #define GPNPUD  S3C64XX_GPNPUD
  46. #define GPMCON S3C64XX_GPMCON
  47. #define GPMDAT  S3C64XX_GPMDAT
  48. #define GPMPUD S3C64XX_GPMPUD
  49.  
  50. #define VIB_ON 0x11
  51.   #defineVIB_OFF 0x22
  52. static const struct file_operations GPIO_Viberator_ctl_ops={
  53.     .owner        = THIS_MODULE,
  54.     .open    = GPIO_VIB_open,
  55.     .read    =GPIO_VIB_read,
  56.     .write    =GPIO_VIB_write,
  57.     .ioctl     = GPIO_VIB_ioctl,
  58.     .release     =GPIO_VIB_release,
  59. };
  60. ssize_t GPIO_VIB_read(struct file * file,char * buf,size_t count,loff_t * f_ops)
  61. {
  62.     printk(" GPIO_VIB_read \r\n");
  63.     gpio_direction_output(S3C64XX_GPM(3), 0);//
  64.     return count ;
  65. }
  66. ssize_t GPIO_VIB_write (struct file * file,const char * buf, size_t count,loff_t * f_ops)
  67. {
  68.       printk(" GPIO_VIB_write \r\n");
  69.       gpio_direction_output(S3C64XX_GPM(3), 1);//
  70.    return count;
  71. }
  72.  
  73. //ssize_t GPIO_VIB_ioctl(struct inode *  inode,struct file * file,unsigned int cmd, long data)
  74. static int GPIO_VIB_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
  75. {
  76.     printk(KERN_ERR"VIB:GPIO_VIB_ioctl --CMD=%x \n",cmd);
  77.     switch(cmd)
  78.         {
  79.            case VIB_ON:
  80.             gpio_direction_output(S3C64XX_GPM(1), 0);//
  81.             gpio_direction_output(S3C64XX_GPM(2), 0);//
  82.             gpio_direction_output(S3C64XX_GPM(3), 0);//
  83.             gpio_direction_output(S3C64XX_GPM(4), 1);//
  84.             printk(KERN_ERR"VIB:GPIO_VIB_ioctl --VIB_ON\n");
  85.             break;
  86.          case VIB_OFF:
  87.             {
  88.             printk(KERN_ERR"VIB:GPIO_VIB_ioctl --VIB_OFF\n");
  89.             gpio_direction_output(S3C64XX_GPM(1), 1);//
  90.             gpio_direction_output(S3C64XX_GPM(2), 1);//
  91.             gpio_direction_output(S3C64XX_GPM(3), 1);//
  92.             gpio_direction_output(S3C64XX_GPM(4), 0);//
  93.             break;
  94.          }
  95.          default:break;
  96.                 
  97.     }
  98.         //gpio_free(S3C64XX_GPN(7));
  99. }
  100. ssize_t GPIO_VIB_open(struct inode * inode,struct file * file)
  101. {
  102. //?£?éêy
  103.   //MOD_INC_USE_COUNT;
  104.   printk("GPIO_VIB_open() \n");   
  105.   return 0;
  106. }
  107. ssize_t GPIO_VIB_release(struct inode * inode, struct file * file)
  108. {
  109.    // MOD_DEC_USE_COUNT;//?£?éêy??
  110.      printk("GPIO_VIB_release() \n");   
  111.     return 0;
  112. }
  113. static int GPIO_VIB_CTL_init(void)
  114. {
  115.     int ret  = -ENODEV;
  116.    int error ;
  117.     printk("---------------------------------------------- \r\n");
  118.     //3?ê??ˉ???ú
  119.         s3c_gpio_cfgpin(S3C64XX_GPM(1), S3C_GPIO_SFN(1));//GPM1 output
  120.         s3c_gpio_cfgpin(S3C64XX_GPM(2), S3C_GPIO_SFN(1));//GPM2 output
  121.         s3c_gpio_cfgpin(S3C64XX_GPM(3), S3C_GPIO_SFN(1));//GPM3 output
  122.         s3c_gpio_cfgpin(S3C64XX_GPM(4), S3C_GPIO_SFN(1));//GPM4 output
  123. #if 1 /*?2ì?·?ê?×¢2á?y?ˉ*/
  124. ret = register_chrdev(Viberator_MAJOR, "viberator", &GPIO_Viberator_ctl_ops);
  125. if (ret < 0) {
  126.     printk(KERN_ERR "VIB: unable to get major %d\n", ret);
  127.     return ret;
  128. }
  129. //′′?¨\uc1class
  130. vib_dev_class = class_create(THIS_MODULE, "viberator");
  131. if (IS_ERR(vib_dev_class)) {
  132.     unregister_chrdev(Viberator_MAJOR, "capi20");
  133.     return PTR_ERR(vib_dev_class);
  134. }
  135. //′′?¨?úμ?£?
  136. device_create(vib_dev_class, NULL, MKDEV(Viberator_MAJOR, 0), NULL, "vib");
  137. // create a point under /dev/class/vib  
  138. //í¨1yé????aá?2?£??y?ˉ?ó??oó£??í?á?ú/dev/class/????éú3é\uc1vib?úμ?£?ó|ó?3ìDò?éò???2ù×÷???t???ù2ù×÷?a???úμ?£?í¨1y\uc1open ,write,read μèoˉêy2ù×÷£??ê?é?éò??′oó??μ?ó|ó?ê?ày3ìDò?£
  139.   return 0;    
  140. #endif
  141. #if 0/* ×¢2á?ˉì?*/
  142.     if ((error = alloc_chrdev_region(&dev, 0, DEVCOUNT, "vibrate")) < 0)
  143.         {
  144.         printk(KERN_ERR
  145.                "VIB: Couldn't alloc_chrdev_region, error=%d\n",
  146.                error);
  147.         return 1;
  148.     }
  149.          printk("dev = %d  \n",dev);
  150.     cdev_p = cdev_alloc();
  151.     cdev_p->ops = &GPIO_Viberator_ctl_ops;
  152.     error = cdev_add(cdev_p, dev, DEVCOUNT);
  153.     if (error) {
  154.         printk(KERN_ERR
  155.                "VIB: Couldn't cdev_add, error=%d\n", error);
  156.         return 1;
  157.     }
  158.  
  159.     vib_dev_class = class_create(THIS_MODULE, "vib-dev");
  160.     if (IS_ERR(vib_dev_class)) {
  161.         res = PTR_ERR(vib_dev_class);
  162.         goto out_unreg_class;
  163.     }
  164.     return 0;
  165. #endif
  166. out_unreg_class:
  167.     class_destroy(vib_dev_class);
  168. return 1;
  169. }
  170.  
  171. static int __init S3C6410_VIB_init(void)
  172. {
  173.     int ret = -ENODEV;
  174.     //μ÷ó?oˉêy   
  175.         printk(KERN_ERR "Auly: S3C6410_VIB_init---\n");
  176.     ret = GPIO_VIB_CTL_init();
  177.     if(ret)
  178.         {
  179.         printk(KERN_ERR "Auly: S3C6410_VIB_init--Fail !!!\n");
  180.         return ret;
  181.     }
  182.     return 0;
  183. }
  184. static void __exit cleanup_GPIO_VIB(void)
  185. {
  186.     //×¢?úéè±?
  187.   //  devfs_unregister_chrdev(Viberator_MAJOR,"gpio_vib_ctl");
  188. #if 0
  189.       cdev_del(cdev_p);
  190.     unregister_chrdev_region(dev, DEVCOUNT);
  191.     class_destroy(vib_dev_class);
  192. #endif
  193. device_destroy(vib_dev_class, MKDEV(Viberator_MAJOR, 0));
  194. class_destroy(vib_dev_class);
  195. unregister_chrdev(Viberator_MAJOR, "viberator");
  196. }
  197. MODULE_LICENSE("GPL");
  198. MODULE_DESCRIPTION("Peter first driver");
  199. MODULE_ALIAS_CHARDEV(Viberator_MAJOR, 0);
  200.  
  201. module_init(S3C6410_VIB_init);
  202. module_exit(cleanup_GPIO_VIB);

 

leddriver.h文件

leddriver.h文件
  1. ssize_t GPIO_VIB_read(struct file * file,char * buf,size_t count,loff_t * f_ops);
  2. ssize_t GPIO_VIB_write (struct file * file,const char * buf, size_t count,loff_t * f_ops);
  3. static int GPIO_VIB_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg);
  4. ssize_t GPIO_VIB_open(struct inode * inode,struct file * file);
  5. ssize_t GPIO_VIB_release(struct inode * inode, struct file * file);
  6. static int GPIO_VIB_CTL_init(void);

Kconfig 文件

Kconfig 文件
  1. config LEDTEST
  2.   tristate "LED test for ARMeasy"
  3.   default n
  4.   help
  5.   this is a LED driver for ARMEASY with S3C6410

Makefile文件

Makefile文件
  1. obj-$(CONFIG_LEDTEST)+=leddriver.o

3、在内核配置里菜单里加入本驱动的配置项

达到的效果是,可以通过内核配置来选择是否把本驱动编译进内核里,也就是出现在make menuconfig 后出来的界面里,可以参考9.8章<android添加新驱动方法>

1)在arch/arm/Kconfig文件里 menu "Device Drivers"与 endmenu之间添加

  1. source "drivers/ledtest/Kconfig"

2)在drivers/Kconfig menu "Device Drivers" 和 endmenu之间添加

  1. source "drivers/ledtest/Kconfig"

3)修改/drivers/Makefile文件

  1. Obj-$(CONFIG_LEDTEST) +=ledtest/

4、编译驱动

在kernel目录下,终端输入

  1. #make menuconfig

“Device Drivers” 下面会看到 “LED test for ARMeasy”,选择它,

保存并退出

  1. #make

这样,就会在/drivers/ledtest目录下得到leddrivr.ko文件,它就是驱动目标文件,已级编译进了zImage 里了,只要用这个kernel烧录到开发板,开机就会自动加载本驱动,

PS,如果发现如上编译,没有在ledtest目录下生成leddriver.ko文件,也就是本根没有去编译本驱动,那就把ledtest目录入到/drivers/misc目录下,相应的修改misc下面,然后,在makefile里,不用选直接写成obj-y += leddriver.o,这样强制的包含进去编译。

三、 应用程序(测试驱动)

用C语言写一个应用,测试上面写的驱动是否工作正常,这是一般的驱动开发流程

主要有两个文件:Android.mk和ledtest.c

1、

在$(YOUR_ANDROID)/external/LEDTEST/目录编写ledtest.c文件,

ledtest.c

ledtest.c
  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <fcntl.h> // contact the open(),close(),read(),write() and so on!
  4.   #define DEVICE_NAME "/dev/vib"//device point
  5. #define LED_ON     0x11
  6. #define LED_OFF     0x22
  7. int main(int argc,char **argv)
  8. {   
  9.     int fd;
  10.     int ret;
  11.     char *i;
  12.     printf("\n start gpio_led_driver test \r\n");
  13.     fd = open(DEVICE_NAME,O_RDWR);//Open device ,get the handle
  14.     printf("fd = %d \n",fd);
  15.     if(fd == -1) //open fail
  16.     {
  17.       printf("open device %s error \n",DEVICE_NAME);
  18.     }
  19.     else
  20.     {
  21.         while(1)
  22.         {
  23.           ioctl(fd,LED_OFF); //call the output function to off LEDs
  24.           sleep(1);//wait 1 second
  25.           ioctl(fd,LED_ON);
  26.           sleep(1);
  27.         }
  28.         ret = close(fd); //close device
  29.         printf("ret = %d \n",ret);
  30.         printf("close gpio_led test \n");
  31.     }
  32.   return 0;
  33. }

2、在$(YOUR_ANDROID)/external/ LEDTEST /目录编写Android.mk文件。这是Android Makefile的标准命名,不要更改。Android.mk文件的格式和内容可以参考其他已有的Android.mk文件的写法,针对helloworld程序的Android.mk文件内容如下:

Android.mk
  1.  
  2. LOCAL_PATH:= $(call my-dir)
  3. include $(CLEAR_VARS)
  4. LOCAL_SRC_FILES:= \\par     hello.c
  5. LOCAL_MODULE := ledtestapp
  6. include $(BUILD_EXECUTABLE)

注意上面LOCAL_SRC_FILES用来指定源文件;

LOCAL_MODULE指定要编译的模块的名字,下一步骤编译时就要用到;

include $(BUILD_EXECUTABLE)表示要编译成一个可执行文件,如果想编译成动态库则可用BUILD_SHARED_LIBRARY,这些可以在

$(YOUR_ANDROID)/build/core/config.mk查到。

、 回到Android源代码顶层目录进行编译:

# cd $(YOUR_ANDROID) && make ledtestapp

例如我这里的实际操作是

#cd android2.1
#make ledtestapp

注意make ledtestapp中的目标名ledtestapp就是上面Android.mk文件中由LOCAL_MODULE指定的模块名。编译结果如下

make ledtestapp
============================================
PLATFORM_VERSION_CODENAME=REL
PLATFORM_VERSION=2.1-update1
TARGET_PRODUCT=generic
TARGET_BUILD_VARIANT=eng
TARGET_SIMULATOR=
TARGET_BUILD_TYPE=release
TARGET_ARCH=arm
HOST_ARCH=x86
HOST_OS=linux
HOST_BUILD_TYPE=release
BUILD_ID=ECLAIR
============================================
/bin/bash: line 0: cd: sdk/layoutopt/app/src/resources: No such file or directory
target thumb C: ledtestapp <= external/LEDTEST/ledtest.c
Install: out/host/linux-x86/bin/apriori
Install: out/host/linux-x86/bin/soslim
target Executable: ledtestapp (out/target/product/generic/obj/EXECUTABLES/ledtestapp_intermediates/LINKED/ledtestapp)
target Non-prelinked: ledtestapp (out/target/product/generic/symbols/system/bin/ledtestapp)
target Strip: ledtestapp (out/target/product/generic/obj/EXECUTABLES/ledtestapp_intermediates/ledtestapp)
Install: out/target/product/generic/system/lib/libdl.so
Install: out/target/product/generic/system/lib/libc.so
Install: out/target/product/generic/system/lib/libstdc++.so
Install: out/target/product/generic/system/lib/libm.so
Install: out/target/product/generic/system/bin/ledtestapp

4、如上面的编译结果所示,编译后的可执行文件存放在

out/target/product/generic/system/bin/目录 可执行文件是ledtestapp

5、拷贝ledtestapp可执行文件到T卡,插入开发板

6、开电,在启动进入android的过程中,串口终端 按回车,进入命令行模式

7、拷贝可执行文件到根目录

#cp /sdcard/ledtestapp /   

8、执行程序

#./ledtestapp

通过上面的步骤,可以看到开发板上相应的LED在闭,每秒钟闪一次!

 

 

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