嵌入式linux与物联网进阶之路五：嵌入式驱动方式点亮led

#include <linux/init.h>  
#include <linux/module.h>
#include <linux/device.h>  
#include <linux/kernel.h>  
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/gpio.h>
#include <linux/string.h>

#define LED_MAJOR 200
#define LED_NAME  "LED"

static int led_open(struct inode *inode, struct file *filep)
    printk("GPIO init \\n");
    return 0;


static int led_write(struct file *filep, const char __user *buf, size_t count, loff_t *ppos)
    return count;


static int led_release(struct inode *inode, struct file *filep)
    printk("Release !! \\n");
    return 0;



static const struct file_operations led_fops = 
    .owner   = THIS_MODULE,
    .open    = led_open,
    .write   = led_write,
    .release = led_release,
;

static int __init led_init(void)

    printk("led control device init success! \\r\\n");

    return 0;


static void __exit led_exit(void)
    printk(" led_exit \\r\\n");


module_init(led_init);
module_exit(led_exit);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("CXSR");

1、 进入sys/class/gpio目录下
2、 执行echo 1 > export命令，可以看出来创建了gpio1的文件夹
3、 进入gpio1文件夹，cat direction查看其值为in，通过vi direction，将其值改为out后， wq保存。
4、 运行 echo 1 > value 命令，则可以设置A1口高电平，设置echo 0 > value 命令，则可以设置A1口低电平。

#include <linux/init.h>  
#include <linux/module.h>
#include <linux/device.h>  
#include <linux/kernel.h>  
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/gpio.h>
#include <linux/string.h>

#define LED_MAJOR 200
#define LED_NAME  "LED"

/*led引脚，这里是A1脚*/
#define LED_PIN 1
static int gpio_status;

/*用户态-内核态交互缓冲区*/
static char recv_msg[20];

/*class名称, 会创建到/sys/class/目录下 */
static const char *CLASS_NAME = "led_control_class";

/*led分类，由此分类可以创建出设备*/
static struct class *led_control_class = NULL;

/*led设备，由此可以实现led控制*/
static struct device *led_control_device = NULL;

/*gpio初始设置*/
static void gpio_config(void)
    if(!gpio_is_valid(LED_PIN))
        printk("Error wrong gpio number !!\\n");
        return;
    
    gpio_request(LED_PIN, "led_ctr");
    /*设置引脚为输出状态*/
    gpio_direction_output(LED_PIN,1);
    /*初始置为高电平*/
    gpio_set_value(LED_PIN,1);
    gpio_status = 1;


/*gpio关闭设置*/
static void gpio_deconfig(void)
    gpio_free(LED_PIN);


/*初始灯*/
static int led_open(struct inode *inode, struct file *filep)
    printk("GPIO init \\n");
    gpio_config();
    return 0;


/*为灯的缓冲区进行数据交换*/
static int led_write(struct file *filep, const char __user *buf, size_t count, loff_t *ppos)
    int cnt = _copy_from_user(recv_msg, buf, count);
    if(0 == cnt)
        /*on命令， 则开灯*/
        if(0 == memcmp(recv_msg, "on", 2))
            printk("LED on! \\n");
            gpio_set_value(LED_PIN, 1);
            gpio_status = 1;
        
        /*off命令，则关灯*/
        else
            printk("LED off! \\n");
            gpio_set_value(LED_PIN, 0);
            gpio_status = 0;
        
    else
        printk("ERROR occur when writing!!\\n");
        return -EIO;
    
    return count;


/*灯设备关闭*/
static int led_release(struct inode *inode, struct file *filep)
    printk("Release !! \\n");
    gpio_deconfig();
    return 0;


/*文件操作结构体*/
static const struct file_operations led_fops = 
    .owner   = THIS_MODULE,
    .open    = led_open,
    .write   = led_write,
    .release = led_release,
;

/*设备初始化*/
static int __init led_init(void)

    int ret = 0;

    /* 1. 注册设备 */
    ret = register_chrdev(LED_MAJOR, LED_NAME,&led_fops);
    if(ret <0)
        printk("register fail!\\r\\n");
        return -EIO;
    
    printk("register success, major number is %d \\r\\n",ret);
    
    /* 2. 创建设备分类 */
    led_control_class = class_create(THIS_MODULE, CLASS_NAME);
    if(IS_ERR(led_control_class))
        unregister_chrdev(LED_MAJOR, LED_NAME);
        return -EIO;
    
　　　
    /* 3. 创建设备 */
    led_control_device = device_create(led_control_class, NULL, MKDEV(LED_MAJOR,0), NULL,LED_NAME);
    if(IS_ERR(led_control_device))
        class_destroy(led_control_class);
        unregister_chrdev(LED_MAJOR, LED_NAME);
        return -EIO;
    

    printk("led control device init success! \\r\\n");

    return 0;


/*设备注销*/
static void __exit led_exit(void)
    printk(" led_exit \\r\\n");
    device_destroy(led_control_class, MKDEV(LED_MAJOR,0));
    class_unregister(led_control_class);
    class_destroy(led_control_class);
    unregister_chrdev(LED_MAJOR,LED_NAME);


module_init(led_init);
module_exit(led_exit);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("CXSR");

KERNELDIR := /home/scy/linux-mi/linux-f1c100s-480272lcd-test/

CURRENT_PATH := $(shell pwd)

obj-m := led1.o

build: kernel_modules

kernel_modules:
	$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) modules CROSS_COMPILE=arm-linux-gnueabi- ARCH=arm
clean:
	$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) clean