一玫膀、編寫GPIO驅(qū)動(dòng)

1. 查找 GPIO 寄存器配置（gpio0為例）
   查手冊(cè)獲取 GPIO0 設(shè)置相關(guān)的寄存器
   GPIO#11 引腳燕少，GPIO1_MODE[1:0] (01)來設(shè)置其為GPIO功能
   通過設(shè)置 GPIO_CTRL_0 [11號(hào)引腳]為1將 GPIO11 設(shè)置為輸出模式
   通過設(shè)置 GPIO_DATA_0 [11號(hào)引腳]為0或1 將 GPIO11 輸出設(shè)置為0或1

二祈惶、創(chuàng)建模塊文件目錄：

1稳摄、在源碼目錄下的/package/kernel/目錄下創(chuàng)建chardrv目錄
2限寞、在chardrv目錄下創(chuàng)建Makefile文件和src目錄
3弛秋、在src目錄下創(chuàng)建Makefile文件和chardrv.c文件

三、編寫驅(qū)動(dòng)文件

1铺韧、chardrv目錄下的Makefile文件內(nèi)容：

#
# Copyright (C) 2008 OpenWrt.org
#
# This is free software, licensed under the GNU General Public License v2.
# See /LICENSE for more information.
#

include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/kernel.mk

PKG_NAME:=chardrv  #字符設(shè)備驅(qū)動(dòng)模塊名稱
PKG_RELEASE:=2   #版本號(hào)

include $(INCLUDE_DIR)/package.mk

define KernelPackage/chardrv #內(nèi)核模塊
  SUBMENU:=Other modules #進(jìn)行歸類
  TITLE:=chardrv  #標(biāo)題
  FILES:=$(PKG_BUILD_DIR)/chardrv.ko #模塊文件
  AUTOLOAD:=$(call AutoLoad,61,chardrv,1) #開啟自動(dòng)裝載
  KCONFIG:=
endef

define KernelPackage/chardrv/description
 Kernel module for register chardrv. #描述
endef

EXTRA_KCONFIG:= \
    CONFIG_CHARDRV=m

EXTRA_CFLAGS:= \
    $(patsubst CONFIG_%, -DCONFIG_%=1, $(patsubst %=m,%,$(filter %=m,$(EXTRA_KCONFIG)))) \
    $(patsubst CONFIG_%, -DCONFIG_%=1, $(patsubst %=y,%,$(filter %=y,$(EXTRA_KCONFIG)))) \

MAKE_OPTS:= \
    ARCH="$(LINUX_KARCH)" \
    CROSS_COMPILE="$(TARGET_CROSS)" \
    SUBDIRS="$(PKG_BUILD_DIR)" \
    EXTRA_CFLAGS="$(EXTRA_CFLAGS)" \
    $(EXTRA_KCONFIG)

define Build/Prepare
    mkdir -p $(PKG_BUILD_DIR)
    $(CP) ./src/* $(PKG_BUILD_DIR)/
endef

define Build/Compile
    $(MAKE) -C "$(LINUX_DIR)" \
        $(MAKE_OPTS) \
        modules
endef

$(eval $(call KernelPackage,chardrv))

2多矮、src目錄下的Makefile文件內(nèi)容：

obj-${CONFIG_CHARDRV} += chardrv.o

3、src目錄下的chardrv.c文件內(nèi)容：

/***************************** 
*
*   字符設(shè)備驅(qū)動(dòng)程序模板
*
*******************************/ 
#include <linux/mm.h> 
#include <linux/miscdevice.h> 
#include <linux/slab.h> 
#include <linux/vmalloc.h> 
#include <linux/mman.h> 
#include <linux/random.h> 
#include <linux/init.h> 
#include <linux/raw.h> 
#include <linux/tty.h> 
#include <linux/capability.h> 
#include <linux/ptrace.h> 
#include <linux/device.h> 
#include <linux/highmem.h> 
#include <linux/crash_dump.h> 
#include <linux/backing-dev.h> 
#include <linux/bootmem.h> 
#include <linux/splice.h> 
#include <linux/pfn.h> 
#include <linux/export.h> 
#include <linux/io.h> 
#include <linux/aio.h> 
#include <linux/kernel.h> 
#include <linux/module.h> 
#include <asm/uaccess.h> 
#include <linux/ioctl.h> 

/****************  基本定義 **********************/ 

#define LED_ON 0
#define LED_OFF 1

//define registers 
volatile unsigned long *GPIO_CTRL_0;// GPIO0-GPIO31 direction control register 
volatile unsigned long *GPIO_DATA_0;// GPIO0-GPIO31 data register 
volatile unsigned long *GPIO1_MODE;// GPIO1 purpose selection register 
volatile unsigned long *AGPIO_CFG;// Analog GPIO configuartion, GPIO14-17 purpose

//加密函數(shù)參數(shù)內(nèi)容： _IOW(IOW_CHAR , IOW_NUMn , IOW_TYPE) 
//加密函數(shù)用于chardrv_ioctl函數(shù)中 
//使用舉例：ioctl(fd , _IOW('L',0x80,long) , 0x1); 

//#define NUMn chardrv 
#define IOW_CHAR 'L' 
#define IOW_TYPE  long 
#define IOW_NUM1  0x80 

//初始化函數(shù)必要資源定義 
//用于初始化函數(shù)當(dāng)中 
//device number; 
    //設(shè)備號(hào) 
    dev_t dev_num; 
//struct dev 

//字符設(shè)備 
    struct cdev chardrv_cdev; 
//auto "mknode /dev/chardrv c dev_num minor_num" 

//自動(dòng)創(chuàng)建設(shè)備對(duì)象 
struct class *chardrv_class = NULL; 
struct device *chardrv_device = NULL; 

/**************** 結(jié)構(gòu)體 file_operations 成員函數(shù) *****************/ 

//open 
static int chardrv_open(struct inode *inode, struct file *file) 
{ 
    printk("chardrv drive open...\n"); 
      *GPIO_DATA_0&=~(1<<11);
    return 0; 
} 
//close 
static int chardrv_close(struct inode *inode , struct file *file) 
{ 
    printk("chardrv drive close...\n"); 
    return 0; 
} 

//read 
static ssize_t chardrv_read(struct file *file, char __user *buffer, size_t len, loff_t *pos) 
{ 
    int ret_v = 0; 
    printk("chardrv drive read...\n"); 
    return ret_v; 
} 


//write 
static ssize_t chardrv_write( struct file *file , const char __user *buffer, size_t len , loff_t *offset ) 
{ 
    int ret_v = 0; 
    printk("chardrv drive write...\n"); 
    return ret_v; 
} 

//unlocked_ioctl 
static int chardrv_ioctl (struct file *filp , unsigned int cmd , unsigned long arg) 
{ 
    int ret_v = 0; 
    printk("chardrv drive ioctl...\n"); 
    switch(cmd) { 
        //常規(guī)： 
        //cmd值自行進(jìn)行修改 
    case LED_ON: 
        { 
            *GPIO_DATA_0 |= (1<<11);
           printk("set gpio 0 on\n"); 
    } 
    break; 

    case LED_OFF:
        {
            *GPIO_DATA_0 &= ~(1<<11);
            printk("set gpio 0 off\n"); 
        }
    break; 
    //帶密碼保護(hù)： 
    //請(qǐng)?jiān)?基本定義"進(jìn)行必要的定義 
    case _IOW(IOW_CHAR,IOW_NUM1,IOW_TYPE): 
    { 
        if(arg == 0x1) //第二條件 
        {

        } 
    } 
    break;  

    default: 
    break; 
    } 
    return ret_v;

} /***************** 結(jié)構(gòu)體： file_operations 哈打，該結(jié)構(gòu)體將驅(qū)動(dòng)中的函數(shù)和應(yīng)用層函數(shù)關(guān)聯(lián)（例如當(dāng)調(diào)用應(yīng)用層調(diào)用open函數(shù)時(shí)就會(huì)調(diào)用驅(qū)動(dòng)中的open函數(shù)）************************/ 
static const struct file_operations chardrv_fops = { 
    .owner = THIS_MODULE, 
    .open = chardrv_open, 
    .release = chardrv_close, 
    .read = chardrv_read, 
    .write = chardrv_write, 
    .unlocked_ioctl = chardrv_ioctl, 
}; 

unsigned char init_flag = 0;
unsigned char add_code_flag = 0;

//使用insmod掛載驅(qū)動(dòng)時(shí)回調(diào) 
static __init int chardrv_init(void) 
{ 
    int ret_v = 0; 
    printk("mydrv drive init...\n"); 
    /*
    函數(shù)alloc_chrdev_region主要參數(shù)說明：
    參數(shù)1： 自動(dòng)分配的設(shè)備號(hào)
    參數(shù)2： 次設(shè)備號(hào)
    參數(shù)3： 創(chuàng)建多少個(gè)設(shè)備
    */ 
    if( ( ret_v = alloc_chrdev_region(&dev_num,0,1,"chardrv") ) < 0 ) //為chardrv動(dòng)態(tài)分配設(shè)備號(hào) 
    { 
        goto dev_reg_error; 
    } 

    init_flag = 1; //標(biāo)示設(shè)備創(chuàng)建成功   

    //打印主設(shè)備號(hào)和次設(shè)備號(hào) 
    printk("The drive info of chardrv:\nmajor: %d\nminor: %d\n", MAJOR(dev_num),MINOR(dev_num)); 

    //關(guān)聯(lián)設(shè)備和操作函數(shù) 
    cdev_init(&chardrv_cdev,&chardrv_fops); 
    //注冊(cè)設(shè)備 
    if( (ret_v = cdev_add(&chardrv_cdev,dev_num,1)) != 0 ) 
    { 
        goto cdev_add_error; 
    } 

    //創(chuàng)建設(shè)備類塔逃，用于自動(dòng)創(chuàng)建設(shè)備 
    chardrv_class = class_create(THIS_MODULE,"chardrv"); 
    if( IS_ERR(chardrv_class) ) 
    { 
        goto class_c_error; 
    } 

    //通過設(shè)備類創(chuàng)建設(shè)備 
    chardrv_device = device_create(chardrv_class,NULL,dev_num,NULL,"chardrv"); 
    if( IS_ERR(chardrv_device) ) 
    { 
        goto device_c_error; 
    } 
    printk("auto mknod success!\n"); 
    //------------   請(qǐng)?jiān)诖颂砑幽某跏蓟绦? --------------// 
    //AGPIO_CFG = (volatile unsigned long *)ioremap(0x1000003c,4); //init register address 
    GPIO1_MODE = (volatile unsigned long *)ioremap(0x10000060,4); 
    GPIO_CTRL_0 = (volatile unsigned long *)ioremap(0x10000600,4); 
    GPIO_DATA_0 = (volatile unsigned long *)ioremap(0x10000620,4); 

    *GPIO1_MODE&=~(1<<1); //set SPIS purpose as GPIO11
    *GPIO1_MODE|=1; 

    *GPIO_CTRL_0|=(1<<11); //set GPIO17 as output pin

    //如果需要做錯(cuò)誤處理，請(qǐng)：goto mydrv_error; 
    add_code_flag = 1;  
    //----------------------  END  ---------------------------// 
    goto init_success; 
    
dev_reg_error: 
    printk("alloc_chrdev_region failed\n"); 
    return ret_v; 

cdev_add_error: 
    printk("cdev_add failed\n"); 
    unregister_chrdev_region(dev_num, 1); 

    init_flag = 0;
    return ret_v; 
class_c_error: 
    printk("class_create failed\n"); 
    cdev_del(&chardrv_cdev); 
    unregister_chrdev_region(dev_num, 1); 
    init_flag = 0;
    return PTR_ERR(chardrv_class); 
device_c_error: 
    printk("device_create failed\n"); 
    cdev_del(&chardrv_cdev); 
    unregister_chrdev_region(dev_num, 1); 
    class_destroy(chardrv_class); 
    init_flag = 0;

    return PTR_ERR(chardrv_device); 
//------------------ 請(qǐng)?jiān)诖颂砑幽腻e(cuò)誤處理內(nèi)容 ----------------// 
chardrv_error: 
   add_code_flag = 0; 
    return -1; 
//--------------------          END         -------------------// 
init_success: 
    printk("chardrv init success!\n"); 
    return 0; 
} 
//使用rmmod卸載驅(qū)動(dòng)是回調(diào)該函數(shù) 
static __exit void chardrv_exit(void) 
{ 
  printk("chardrv drive exit...\n"); 
    if (add_code_flag == 1)
    {
        printk("free your resources...\n"); 
        iounmap(GPIO1_MODE); 
        iounmap(GPIO_CTRL_0); 
        iounmap(GPIO_DATA_0); 
        printk("free finish\n");
    }

    //釋放初始化使用到的資源; 
    if (init_flag == 1) {
        cdev_del(&chardrv_cdev); 
        unregister_chrdev_region(dev_num, 1); 
        device_unregister(chardrv_device); 
        class_destroy(chardrv_class); 
    }
}

/**************** module operations**********************/
 //聲明加載函數(shù)和卸載函數(shù) 
 module_init(chardrv_init); 
 module_exit(chardrv_exit); 
 //some infomation 

 MODULE_LICENSE("GPL v2"); 
 MODULE_AUTHOR("LFJ"); 
 /*********************  The End ***************************/

四料仗、編譯驅(qū)動(dòng)

1湾盗、切換到源碼目錄的根目錄：如openwrt目錄
2、make menconfig
3立轧、選擇Kernel modules -->other modules-->kmod-chardrv格粪，保存退出
4、sudo make package/kernel/chardrv/compile V=99
5氛改、編譯成功后的文件在openwrt/bin/ramips/packages/kernel/ 目錄下的kmod-chardrv_4.4.7-2_ramips_24kec.ipk文件

五帐萎、裝載驅(qū)動(dòng)模塊到內(nèi)核和卸載模塊

1、可以通過scp將kmod-chardrv_4.4.7-2_ramips_24kec.ipk文件拷貝到板子上
2胜卤、在板子上執(zhí)行opkg install kmod-chardrv_4.4.7-2_ramips_24kec.ipk 執(zhí)行成功后在/lib/modules/4.4.7/目錄下可以找到chardrv.ko文件
3疆导、insmod chardrv.ko #將裝載到內(nèi)核中
4、rmmod chardrv.ko #將chardrv.ko模塊從內(nèi)核中卸載

六葛躏、應(yīng)用程序測(cè)試

1澈段、編寫應(yīng)用程序測(cè)試代碼my_led.c

/*************************************************************************
    > File Name: led_app.c
    > Author: 
    > Mail: LFJ
    > Created Time: 2019年01月17日 星期四 17時(shí)56分19秒
 ************************************************************************/
#include <stdio.h> 
#include <string.h> 
#include <fcntl.h> 
#include <unistd.h> 
#include <sys/types.h> 
#include <sys/stat.h> 
#include <sys/ioctl.h> 
#define LED_ON 0 
#define LED_OFF 1 

char str_dev[]="/dev/leddrv";
int main(int argc,char* argv[]) 
{ 
    int fd;

    if(argc!=2) { 
        printf(" %s <on|off> to turn on or off LED on GPIO11\n",argv[0]); 
        return -1; 
    }
    fd=open(str_dev,O_RDWR|O_NONBLOCK); 
    if(fd<0) { 
        printf("can't open %s \n",str_dev); 
        return -1; 
    } if(!strcmp("on",argv[1])) {
        while(1) { 
            ioctl(fd,LED_ON); 
            sleep(1);
            ioctl(fd,LED_OFF); 
            sleep(1);
        } 
    } else if(!strcmp("off",argv[1])) {
        ioctl(fd,LED_OFF);
    } else { 
        printf(" %s <on|off> to turn on or off LED on GPIO11\n",argv[0]); 
        return -1; 
    }

 return 0; 
}

2、編譯程序
執(zhí)行mipsel-openwrt-linux-gcc my_led.c -o my_led
3舰攒、通過scp將my_led可執(zhí)行文件拷貝到openwrt板子上./ my_led on執(zhí)行败富，執(zhí)行成功GPIO0將會(huì)循環(huán)亮、滅