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实现设备与驱动分离的思想

先解析设备信息，成功后执行probe函数控制相关硬件信息

实例：文章来源地址https://www.toymoban.com/news/detail-513864.html

/*
 * Filename: /home/ubuntu/vscode/day9_/pdrv.c
 * Path: /home/ubuntu/vscode/day9_
 * Created Date: Sunday, June 25th 2023, 1:51:32 pm
 * Author: xinyue
 * 
 * Copyright (c) 2023 Your Company
 */
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include "led.h"

struct resource* res;
unsigned int irqnum;
//主设备号
int major = 0;
struct gpio_desc *gpionum1, *gpionum2, *gpionum3; //描述GPIO结构体

char kbuf[1024] = {0};

struct class* cls; //向上提交目录信息结构体指针
struct device* dev; //向上提交设备结点结构体指针

struct device_node* dnode;

int mycdev_open (struct inode * inode, struct file * file)
{
    printk("%s:%s:%d\n", __FUNCTION__, __FILE__, __LINE__);
    return 0;
}

long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    //逻辑控制
    switch(cmd)
    {
        case LED1_ON:
            gpiod_set_value(gpionum1, 1);
            break;
        case LED1_OFF:
            gpiod_set_value(gpionum1, 0);
            break;
        case LED2_ON:
            gpiod_set_value(gpionum2, 1);
            break;
        case LED2_OFF:
            gpiod_set_value(gpionum2, 0);
            break;
        case LED3_ON:
            gpiod_set_value(gpionum3, 1);
            break;
        case LED3_OFF:
            gpiod_set_value(gpionum3, 0);
            break;
        default:
            break;
    }
    return 0;
}

int mycdev_close (struct inode * inode, struct file * file)
{
    printk("%s:%s:%d\n", __FUNCTION__, __FILE__, __LINE__);
    return 0;
}

struct file_operations fops = {
    .open=mycdev_open,
    .unlocked_ioctl=mycdev_ioctl,
    .release=mycdev_close
};

int dev_create(void)
{
    //向上提交目录信息
    cls = class_create(THIS_MODULE, "mycdev");
    if(IS_ERR(cls)) //返回值指向错误码区
    {
        printk("class_create failed\n");
        return -PTR_ERR(cls);
    }
    printk("class_create succeeded\n");
    //向上提交设备结点信息
    dev = device_create(cls, NULL, MKDEV(major, 0), NULL, "mycleds");
    if(IS_ERR(dev))
    {
        printk("device_create failed\n");
        return -PTR_ERR(dev);
    }
    printk("device_create succeeded\n");
    return 0;
}

//解析设备树结点，找出GPIO编号
int find_gpiox(void)
{
    //根据结点找到对应的GPIO编号,并申请使用编号，初始化为低电平输出模式
    gpionum1 = gpiod_get_from_of_node(dnode, "led1", 0, GPIOD_OUT_LOW, NULL);//led1
    if(IS_ERR(gpionum1))
    {
        printk("gpiod_get_from_of_node failed\n");
        return -PTR_ERR(gpionum1);
    }
    gpionum2 = gpiod_get_from_of_node(dnode, "led2", 0, GPIOD_OUT_LOW, NULL);//led2
    if(IS_ERR(gpionum2))
    {
        printk("gpiod_get_from_of_node failed\n");
        return -PTR_ERR(gpionum2);
    }
    gpionum3 = gpiod_get_from_of_node(dnode, "led3", 0, GPIOD_OUT_LOW, NULL);//led3
    if(IS_ERR(gpionum3))
    {
        printk("gpiod_get_from_of_node failed\n");
        return -PTR_ERR(gpionum3);
    }
    return 0;
}

//定义相关成员函数
//probe函数用于匹配设备成功后执行
int pdrv_probe(struct platform_device *pdev)//当和设备匹配成功之后执行probe
{
    major = register_chrdev(0, "mycleds", &fops);
    if(0 == major)
    {
        printk("%s\n", "mycdev register failed");
        return -1;
    }
    printk("%s:%s:%d major=%d\n", __FUNCTION__, __FILE__, __LINE__, major);
    dev_create(); //向上提交信息(创建设备结点)
    dnode = pdev->dev.of_node; //解析成功后，该指针存放了成功找到的设备结点对象的指针
    find_gpiox(); //初始化GPIO引脚
    //printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0; 
}
//remove用于和设备分离时执行
int pdrv_remove(struct platform_device *pdev)//当设备和驱动分离时执行remove
{
    //释放申请的编号
    gpiod_put(gpionum1);
    gpiod_put(gpionum2);
    gpiod_put(gpionum3);
    //销毁设备节点
    device_destroy(cls, MKDEV(major, 0));
    class_destroy(cls);
    //注销设备驱动
    unregister_chrdev(major, "mycleds");
    //printk("%s:%s:%d\n",__FILE__,__func__,__LINE__);
    return 0;  
}

//在驱动中创建一个用于设备树匹配的表
struct of_device_id oftable[]={
    {.compatible="hqyj,myplatform",},
    {.compatible="hqyj,myplatform1",},
    {.compatible="hqyj,myplatform2",},
    {},
};

//分配对象并初始化
struct platform_driver pdrv={
    .probe=pdrv_probe,
    .remove=pdrv_remove,
    .driver={
        .name = "hqyj",
        .of_match_table = oftable //设备树匹配方式
    }
};

//一键注册宏，代替入口出口
module_platform_driver(pdrv);
MODULE_LICENSE("GPL");

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