openwrt通过字符驱动的方式控制LED灯光

1、概述

通过在openwrt源码目录下（或者SDK包的openwrt的目录下）编写gpio的字符驱动生成ipk包，发送到开发板上insmod加载驱动，然后通过编写APP来进行测试。

2、在源码目录的 ./package/kernel下创建gpio_control_driver文件夹

mkdir gpio_control_driver

3、在gpio_control_driver文件夹下创建Makefile和src文件夹

mkdir src
touch Makefile

4、编写Makefile

include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/kernel.mk
PKG_NAME:=gpio_control_driver
PKG_RELEASE:=1
include $(INCLUDE_DIR)/package.mk
define KernelPackage/$(PKG_NAME)
  SUBMENU:=Other modules
  DEPENDS:=@GPIO_SUPPORT
  TITLE:=Driver for FA156 gpios control
  FILES:=$(PKG_BUILD_DIR)/gpio_control_driver.ko
  AUTOLOAD:=$(call AutoLoad,30,gpio_control_driver)
endef
define KernelPackage/$(PKG_NAME)/description
 Kernel module to control gpios for  FA156
endef
define Build/Prepare
    mkdir -p $(PKG_BUILD_DIR)
    cp -rf  ./src/* $(PKG_BUILD_DIR)/
endef
define Build/Compile
    $(MAKE) -C "$(LINUX_DIR)" \
        CROSS_COMPILE="$(TARGET_CROSS)" \
        ARCH="$(LINUX_KARCH)" \
        SUBDIRS="$(PKG_BUILD_DIR)" \
        EXTRA_CFLAGS="$(BUILDFLAGS)" \
        $(EXTRA_KCONFIG) \
        modules
endef
$(eval $(call KernelPackage,$(PKG_NAME)))

makefile注释在https://editor.csdn.net/md/?articleId=109803571这篇文章里，我详细注释了。

5、进入src目录下创建gpio_control_driver.c 、 Makefile

touch gpio_control_driver.c 
touch Makefile

6、编写gpio_control_driver.c 、Makefile

Makefile：

obj-m := gpio_control_driver.o

gpio_control_driver.c:

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#define NEWCHRLED_CNT 1 
#define NEWCHRLED_NAME "gpio_control" 
#define GPIO_CONTROL_SET_OUT 0x01
#define GPIO_CONTROL_SET_IN 0x02
//#define GPIO_CONTROL_GET_DIRECTION 0x03
#define GPIO_CONTROL_SET_VALUE 0x04
#define GPIO_CONTROL_GET_VALUE 0x05
#define GPIO_CONTROL_REQUEST_GPIO 0x06
#define GPIO_CONTROL_FREE_GPIO 0x07
#define GET_GPIO_NUM(arg1) (unsigned char)((arg1 >> 24) & 0xff)
#define GET_GPIO_VALUE(arg1) (unsigned char)((arg1 >> 16) & 0xff)
struct  gpio_control_dev{ 
    dev_t devid;            
    struct cdev cdev;        
    struct class *class;        
    struct device *device;    
    int major;                
    int minor;                
};
struct  gpio_control_dev  gpio_control;
static int gpio_control_open(struct inode *pinode, struct file *pfile)
{ 
        printk("***%s***\n",__func__);
        return 0;
}
static int gpio_control_release(struct inode *pinode, struct file *pfile)
{ 
        printk("***%s***\n",__func__);
        return 0;
}
static long gpio_control_ioctl(struct file *pfile, unsigned int cmd, unsigned long arg)
{ 
    int ret;
    unsigned char gpio_number;
    unsigned char gpio_value;
    gpio_number = GET_GPIO_NUM(arg);
    gpio_value  = GET_GPIO_VALUE(arg);
    switch (cmd){ 
    case GPIO_CONTROL_SET_OUT:
        ret = gpio_direction_output(gpio_number, gpio_value);
        if (ret < 0){ 
            return -1;
        }
        break;
    case GPIO_CONTROL_SET_IN:
        ret = gpio_direction_input(gpio_number);
        if (ret < 0){ 
            return -1;
        }
        break;
    case GPIO_CONTROL_SET_VALUE:
        gpio_set_value(gpio_number, gpio_value);
        break;
    case GPIO_CONTROL_GET_VALUE:
        ret = gpio_get_value(gpio_number);
        if (ret < 0){ 
            return -1;
        }
        break;
    case GPIO_CONTROL_REQUEST_GPIO:
        if (0 > gpio_request(gpio_number, "gpio_ctrl")){ 
            return -1;
        }
        break;
    case GPIO_CONTROL_FREE_GPIO:
        gpio_free(gpio_number);
        break;
    default:
        printk("***Unknown command:0x%02X\n***\n", cmd);
        break;
    }
    return 0;
}
static const struct file_operations gpio_control_ops = { 
                .owner                  = THIS_MODULE,
                .open                   = gpio_control_open,
                .release                = gpio_control_release,
                .unlocked_ioctl         = gpio_control_ioctl,
};
static int __init led_init(void)
{ 
    unsigned int ret = 0;
    /*1. register chrdev*/
    if (gpio_control.major) {         
        gpio_control.devid = MKDEV(gpio_control.major, 0);
        ret =register_chrdev_region(gpio_control.devid, NEWCHRLED_CNT, NEWCHRLED_NAME);
    } else {                         
        ret = alloc_chrdev_region(&gpio_control.devid, 0, NEWCHRLED_CNT, NEWCHRLED_NAME);    
    }
    if(ret < 0 )
    { 
        goto faial_alloc_chrdeev;
    }
    /* 2. init chrdev*/
    gpio_control.cdev.owner = THIS_MODULE;
    cdev_init(&gpio_control.cdev, &gpio_control_ops);
    /* 3. add chrdev */
    ret = cdev_add(&gpio_control.cdev, gpio_control.devid, NEWCHRLED_CNT);
    if (ret < 0)
    { 
        goto faial_add_chrdeev;
    }
    /* 4. create class */
    gpio_control.class = class_create(THIS_MODULE, NEWCHRLED_NAME);
    if (IS_ERR(gpio_control.class)) { 
        goto  faial_create_class;
    }
    /* 5. create device */
    gpio_control.device = device_create(gpio_control.class, NULL, gpio_control.devid, NULL, NEWCHRLED_NAME);
    if (IS_ERR(gpio_control.device)) { 
        goto faial_create_device;
    }
    return 0;
faial_create_device:
    device_destroy(gpio_control.class, gpio_control.devid);
faial_create_class:
    class_destroy(gpio_control.class);
faial_add_chrdeev:
    cdev_del(&gpio_control.cdev);
faial_alloc_chrdeev:
    unregister_chrdev_region(gpio_control.devid, NEWCHRLED_CNT);
}
static void __exit led_exit(void)
{ 
    cdev_del(&gpio_control.cdev);
    unregister_chrdev_region(gpio_control.devid, NEWCHRLED_CNT);
    device_destroy(gpio_control.class, gpio_control.devid);
    class_destroy(gpio_control.class);
}
module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("qingmu");

7、配置menuconfig

make  menuconfig

8、编译

回到openwrt的根目录下

make ./package/kernel/gpio_control_driver/compile V=s

9、把生成的ipk包发送到板子上去

找到生成的ipk包
发送到板子上去

scp ./bin/ipq/packages/base/kmod-gpio_control_driver_4.4.60-1_ipq.ipk root@192.168.1.1:/root

10、安装ipk包

opkg install kmod-gpio_control_driver_4.4.60-1_ipq.ipk

11、加载驱动

在/lib/modules/4.19.57/下可以找到gpio_control_driver.ko,执行

insmod gpio_control_driver.ko

这样驱动就加载完成了，如果想卸载，可以执行

rmmod gpio_control_driver.ko

12、驱动测试

12.1、同样的方式把测试文件也打包成ipk包发送到板子上运行

• 1、在openwrt的源码目录下（SDK包的openwrt的目录下）的./package目录下创建gpio_test目录，

  mkdir gpio_test

• 2、在gpio_test的目录下创建Makefile和src目录

  touch Makefile
  mkdir src

• 3、编写Makefile
  makefile:

  obj-m := gpio_control_driver.o

• 4、在src的目录下创建gpiotest.c、gpio_test.h、Makefile

  touch gpiotest.c
  touch gpiotest.h
  touch Makefile

gpio_test.c :

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include "gpio_test.h"
static unsigned char gpio_pin;//define GPIOs to be use
static int gpio_dev_fd;
void demo1_release(int signal_no)
{ 
    ioctl(gpio_dev_fd, GPIO_CONTROL_SET_IN, GPIO_IOCTL_PRAM(gpio_pin, 0));
    ioctl(gpio_dev_fd, GPIO_CONTROL_FREE_GPIO, GPIO_IOCTL_PRAM(gpio_pin, 0));
    exit(0);
}
//指定管脚拉高, 拉低
int set_gpio(unsigned char pin, int state)
{    
    if(state == 1)
    { 
        ioctl(gpio_dev_fd, GPIO_CONTROL_SET_VALUE, GPIO_IOCTL_PRAM(pin, 1));
    }
    else if(state == 0)
    { 
        ioctl(gpio_dev_fd, GPIO_CONTROL_SET_VALUE, GPIO_IOCTL_PRAM(pin, 0));
    }
    else
    { 
        printf("No such set\n");
        goto ERROR;
    }
    return 0;
    ERROR:
        return -1; 
}
int gpio_init(int pin)
{ 
    int ret;
    gpio_pin = pin;
    gpio_dev_fd = open(GPIO_CONTROL_DEVICE_PATH, O_RDWR);//open gpio device
    if (gpio_dev_fd < 0){ 
        printf("###open %s ERROR###\n", GPIO_CONTROL_DEVICE_PATH);
        goto ERROR;
    }else{ 
        printf("***open %s success***\n", GPIO_CONTROL_DEVICE_PATH);
    }
    ret = ioctl(gpio_dev_fd, GPIO_CONTROL_REQUEST_GPIO, GPIO_IOCTL_PRAM(pin, 0));
    if (ret < 0){ 
        printf("###request GPIO %d error###", pin);
        goto ERROR;
    }
    ret = ioctl(gpio_dev_fd, GPIO_CONTROL_SET_OUT, GPIO_IOCTL_PRAM(pin, 0));
    if (ret < 0){ 
        printf("###set GPIO %d output error###", pin);
        goto ERROR;
    }
    signal(SIGINT, demo1_release);//register terminal signal
    return 0;
    ERROR:
        return -1; 
}
int main()
{ 
    gpio_init(30);
    gpio_init(29);
    while(1)
    { 
        set_gpio(30, 0);
        usleep(200000);
        set_gpio(30, 1);
        usleep(200000);
        set_gpio(29, 0);
        usleep(200000);
        set_gpio(29, 1);
        usleep(200000);
    }
    return 0;
}

注意：我这里的LED的灯的gpio口是GPIO30和GPIO29，大家个根据自己的GPIO口进行更改

gpio_test.h :

#ifndef GPIO_CONTROL_TEST_H_
#define GPIO_CONTROL_TEST_H_
#define GPIO_CONTROL_DEVICE_PATH "/dev/gpio_control"
#define GPIO_IOCTL_PRAM(gpio_num, arg1) (((unsigned long)gpio_num << 24) + ((unsigned long)arg1 << 16))
#define GET_GPIO_NUM(arg1) (unsigned char)((arg1 >> 24) & 0xff)
#define GET_GPIO_VALUE(arg1) (unsigned char)((arg1 >> 16) & 0xff)
//IOCTRL CMDs
#define GPIO_CONTROL_SET_OUT 0x01
#define GPIO_CONTROL_SET_IN 0x02
//#define GPIO_CONTROL_GET_DIRECTION 0x03
#define GPIO_CONTROL_SET_VALUE 0x04
#define GPIO_CONTROL_GET_VALUE 0x05
#define GPIO_CONTROL_REQUEST_GPIO 0x06
#define GPIO_CONTROL_FREE_GPIO 0x07
int set_gpio(unsigned char pin, int state);
int gpio_init(int pin);
void delay_ms(int ms);
#endif

• 5、回到openwrt根目录下编译

  make ./package/gpio_test/compile V=s

• 6、找到对应的ipk包并发送到板子上

  find ./ -name gpio_te*.ipk

发送到对应的开发板，这里大家根据自己的实际情况来：

scp ./bin/ipq/packages/base/gpio_test_1-1.0_ipq.ipk root@192.168.1.1:/root

• 6、安装goio_test的ipk包

  opkg install gpio_test_1-1.0_ipq.ipk

• 7、运行gpio_test应用程序

  gpio_test

此时LED灯开始闪烁，大功告成

来源：https://blog.csdn.net/weixin_45309916/article/details/109811535

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