beep实验

1.设备树代码

2.驱动代码

#include <linux/types.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/ide.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/errno.h> 
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <asm/mach/map.h>

#define BEEP_CNT         1
#define BEEP_NAME        "beep"
#define BEEPOFF          0            /* 关闭蜂鸣器 */
#define BEEPON           1            /* 打开蜂鸣器 */

/* beep设备结构体 */
struct beep_dev{
    dev_t           devid;          /* 设备号 */
    struct cdev     cdev;           /* 字符设备 */
    struct class    *class;         /* 类 */
    struct device   *device;        /* 设备 */
    int             major;          /* 注设备号 */
    int             minor;          /* 次设备号 */
    struct device_node *nd;         /* 设备节点 */
    int beep_gpio;                   /* 设备树里面的编号 */
};

struct beep_dev beep; /* 定义LED结构体 */

void led_switch(struct beep_dev *dev, u8 sta)
{
    if(sta == BEEPON) {
        gpio_set_value(dev->beep_gpio, 0);
    }else if(sta == BEEPOFF) {
        gpio_set_value(dev->beep_gpio, 1);
    } else {
        printk("Error Number! \r\n");
    }
}

static int beep_open(struct inode *inode, struct file *filp)
{
    filp->private_data = &beep;
    return 0;
}

static int beep_release(struct inode *inode, struct file *filp)
{
    //struct beep_dev *dev = (struct beep_dev *)filp->private_data;
    return 0;
}

static ssize_t beep_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
{
    int retvalue;
    unsigned char databuf[1];
    // unsigned char ledstat; 
    struct beep_dev *dev = (struct beep_dev *)filp->private_data;

    retvalue = copy_from_user(databuf, buf, count);
    if(retvalue < 0) {
        printk("kernel write failed!\r\n");
        return -EFAULT;
    }
    led_switch(dev, databuf[0]);   
    
    return 0;
}

static ssize_t beep_read(struct file *filp, char __user *buf,
size_t cnt, loff_t *offt)
{
    return 0;
}

/* 字符设备操作集 */
static const struct file_operations beep_fops = {
    .owner = THIS_MODULE,
    .write = beep_write,
    .open = beep_open,
    .read = beep_read,
    .release = beep_release,
};

/* 模块入口函数 */
static int __init beep_init(void)
{
    /* 定义一些所需变量 */
    int ret = 0;

    /* 1. 注册字符设备驱动 */
    beep.major = 0;
    if(beep.major) {
        beep.devid = MKDEV(beep.major, 0);
        ret = register_chrdev_region(beep.devid, BEEP_CNT, BEEP_NAME);  
    } else {
        alloc_chrdev_region(&beep.devid, 0, BEEP_CNT, BEEP_NAME);
        beep.major = MAJOR(beep.devid);
        beep.minor = MINOR(beep.devid);
    }
    if(ret < 0){
        goto fail_devid;
    }
    printk("Make devid success! \r\n");
    printk("major = %d, minor = %d \r\n", beep.major, beep.minor);

    /* 2. 初始化cdev */
    beep.cdev.owner = THIS_MODULE;
    cdev_init(&beep.cdev, &beep_fops);
    ret = cdev_add(&beep.cdev, beep.devid, BEEP_CNT);
    if (ret < 0){
        goto fail_cdev;
    } else {
        printk("Cdev add sucess! \r\n");
    }

    /* 3. 自动创建设备节点 */
    beep.class = class_create(THIS_MODULE, BEEP_NAME);
    if(IS_ERR(beep.class)) {
        ret = PTR_ERR(beep.class);
        goto fail_class;
    } else {
        printk("Class create sucess! \r\n");
    }

    beep.device = device_create(beep.class, NULL, beep.devid, NULL, BEEP_NAME);
    if(IS_ERR(beep.device)) {
        ret = PTR_ERR(beep.device);
        goto fail_device;
    } else {
        printk("Device create sucess! \r\n");
    }

    /* 1. 获取设备节点 */
    beep.nd = of_find_node_by_path("/beep");
    if( beep.nd == NULL){
        ret = -EINVAL;
        printk("beep node can not found!\r\n");
        goto fail_findnd;
    }

    /* 2. 获取设备所对应的gpio */
    /* 注意第三个参数，因为只有一个索引，所以是0 */
    beep.beep_gpio = of_get_named_gpio(beep.nd, "beep-gpios", 0);
    if( beep.beep_gpio < 0) {
        printk("Can't find beep gpio \r\n");
        ret = -EINVAL;
        goto fail_findnd;
    }
    printk("Beep gpio num = %d. \r\n", beep.beep_gpio);
    
    /* 3. 获取到IO之后，申请IO */
    /* 作用是申请之后，就能知道该IO是否被其他函数占用 */
    /* 如果申请失败，说明被战用啦 */
    /* 解决方法：1.搜索所需管脚 2.在搜索复用管脚，例如 &gpio1 3 */
    ret = gpio_request(beep.beep_gpio, "beep-gpio");
    if(ret) {
        printk("Failed to request the beep gpio! \r\n");
        ret = -EINVAL;
        goto fail_findnd;
    }

    /* 4. 使用IO */
    ret = gpio_direction_output(beep.beep_gpio, 1); /* 设置输出，默认高电平不点亮 */
    if(ret < 0){
        printk("Failed to set input or output! \r\n");
        goto fail_set_output;
    }

    /* 5. 输出低电平，打开蜂鸣器 */
    gpio_set_value(beep.beep_gpio, 0);

    printk("beep init! \r\n");
    return 0;

/* 错误处理 */
fail_set_output:
    gpio_free(beep.beep_gpio);
fail_findnd:
    device_destroy(beep.class, beep.devid);
fail_device:
    class_destroy(beep.class);
fail_class:
    cdev_del(&beep.cdev);
fail_cdev:
    unregister_chrdev_region(beep.devid, BEEP_CNT);
fail_devid:
    return ret;
}

/* 模块出口函数 */
static void __exit beep_exit(void)
{
    /* 关灯 */
    gpio_set_value(beep.beep_gpio, 1);

    /* 1. 释放设备号 */
    cdev_del(&beep.cdev);
    /* 2. 注销设备号 */
    unregister_chrdev_region(beep.devid, BEEP_CNT);
    /* 3. 摧毁设备 */
    device_destroy(beep.class, beep.devid);
    /* 4.摧毁类 */
    class_destroy(beep.class);

    /* 释放IO， 和上面的申请IO对应 */
    gpio_free(beep.beep_gpio);

    printk("beep exit! \r\n");
}

/* 模块入口和出口注册 */
module_init(beep_init);
module_exit(beep_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Shao Zheming");

3.应用代码

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

/* 
 * argc: 应用程序参数个数
 * argv[]: 参数是什么，具体的参数，说明参数是字符串的形式
 * .chrdevbaseApp <filename> <0:1> 0表示关灯，1表示开灯
 * .chrdevbaseApp /dev/led 0 关灯
 * .chrdevbaseApp /dev/led 1 开灯
 * */

#define BEEPOFF      0   /* 关灯 */
#define BEEPON       1   /* 开灯 */

int main(int argc, char *argv[])
{
    if(argc != 3)
    {
        printf("Error Usage!\r\n");
        return -1;
    }
    
    char *filename;
    int fd, retValue;
    unsigned char dataBuf[1];

    filename = argv[1];
    fd = open(filename, O_RDWR);
    if(fd < 0)
    {
        printf("file %s open failed! \r\n", filename);
        return -1;
    }

    dataBuf[0] = atoi(argv[2]);
    retValue = write(fd, dataBuf, sizeof(dataBuf));
    if(retValue < 0){
        printf("Led Control Failed \r\n");
        close(fd);
        return -1;
    }
    close(fd);
    return 0;
}