嵌入式开发记录-day45 pinctrl子系统配置管脚为输入

1、 硬件部分

　　使用开发板上的home（gpx1 1）按键，作为GPIO的输入。按下低电平，默认高电平

2、设备树修改

　　屏蔽掉其它代码对gpx1 1的引用，在前面几节设备树的基础上，添加设备树注册部分

itop_gpio_in {
compatible = "gpio_in";
status = "okay";
gpioin = <&gpx1 1 0>;
};

3、驱动代码

#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_gpio.h>

#include <linux/miscdevice.h>
#include <linux/fs.h>

#define DRIVER_NAME "gpio_in"

int gpio_pin = 0;

int gpio_open(struct inode *inode,struct file *filp)
{
    printk("Device Opened Success!\n");
    return nonseekable_open(inode,filp);
}

int gpio_release(struct inode *inode,struct file *filp)
{
    printk("Device Closed Success!\n");
    return 0;
}

long gpio_ioctl(struct file *filp,unsigned int cmd,unsigned long arg)
{
    printk("debug: gpio_ioctl cmd is %d,arg is %d\n" , cmd,arg);

    switch(cmd)
    {
        case 0:
        case 1:
            return gpio_get_value(gpio_pin);  // 获取管脚电平值
            break;

        default:
            return -EINVAL;
    }
    return 0;
}

static struct file_operations gpio_ops = {
    .owner     = THIS_MODULE,
    .open     = gpio_open,
    .release= gpio_release,
    .unlocked_ioctl     = gpio_ioctl,
};

static struct miscdevice gpio_dev = {
    .minor    = MISC_DYNAMIC_MINOR,
    .fops    = &gpio_ops,
    .name    = DRIVER_NAME,
};

static int gpio_probe(struct platform_device * pdev)
{
    struct device_node *node = pdev->dev.of_node;
    int ret,value;
    
    printk("gpio init\n");
    
    // 获取管脚编号
    gpio_pin = of_get_named_gpio(node, "gpioin", 0);
    if (gpio_pin < 0)
        printk("gpio_pin is not available \n");
    
    // 根据管脚编号申请空间
    ret = gpio_request(gpio_pin, "gpio-in");
    if(ret!=0){
        printk("gpio_pin request %d faigpio.", gpio_pin);
        return ret;
    }
    printk("gpio_pin is %d\n",gpio_pin);
    
    // 释放管脚
    gpio_free(gpio_pin);
    // 配置为直接输入
    gpio_direction_input(gpio_pin);
    // 获取管脚电平
    value = gpio_get_value(gpio_pin);
    printk("the value is %d\n",value);
    // 杂项设备注册
    ret = misc_register(&gpio_dev);
    if(ret<0){
        printk("gpio:register device faigpio!\n");
        goto exit;
    }
    
    return 0;
exit:
    misc_deregister(&gpio_dev);
    return ret;
}

static int gpio_remove(struct platform_device * pdev)
{
    printk(KERN_ALERT "Goodbye, curel world, this is remove\n");
    misc_deregister(&gpio_dev);
    return 0;
}

static const struct of_device_id of_gpio_dt_match[] = {
    {.compatible = DRIVER_NAME},
    {},
};

MODULE_DEVICE_TABLE(of,of_gpio_dt_match);

static struct platform_driver gpio_driver = {
    .probe     = gpio_probe,
    .remove = gpio_remove,
    .driver = {
        .name = DRIVER_NAME,
        .owner = THIS_MODULE,
        .of_match_table = of_gpio_dt_match,
        },
};

static int gpio_init(void)
{
    printk(KERN_ALERT "Hello, world\n");
    return platform_driver_register(&gpio_driver);
    return 0;
}

static void gpio_exit(void)
{
    printk(KERN_ALERT "Goodbye, curel world\n");
    platform_driver_unregister(&gpio_driver);
}

module_init(gpio_init);
module_exit(gpio_exit);

MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("rty");
MODULE_DESCRIPTION("topeet4412_regiter_dev_drv");

4、应用代码

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

int main(int argc,char **argv)
{
    int fd;
    
    if(argc!=2){
        printf("arvc is 2:\nargv1 is device_node\n");
    }
    
    if((fd = open(argv[1], O_RDWR|O_NOCTTY|O_NDELAY))<0){
        printf("open %s failed\n",argv[1]);   
        return -1;
    }
    else{
        printf("open %s ok\n",argv[1]); 
        printf("key value is %d\n",ioctl(fd,0,0));        
    }
    close(fd);
    return 0;
}

5、待测试