linux驱动程序 实例

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

#define DEVICE_NAME "led_driver"
#define GPIO_PIN 18 // 假设使用GPIO18

static int major_number;
static struct class *led_class;
static struct device *led_device;

static int led_open(struct inode *inode, struct file *file)
{
    printk(KERN_INFO "LED driver opened
");
    return 0;
}

static long led_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    switch (cmd) {
        case 0: // 关闭LED
            gpio_set_value(GPIO_PIN, 0);
            printk(KERN_INFO "LED turned off
");
            break;
        case 1: // 打开LED
            gpio_set_value(GPIO_PIN, 1);
            printk(KERN_INFO "LED turned on
");
            break;
        default:
            printk(KERN_INFO "Invalid command
");
            return -EINVAL;
    }
    return 0;
}

static struct file_operations fops = {
    .owner = THIS_MODULE,
    .open = led_open,
    .unlocked_ioctl = led_ioctl,
};

static int __init led_init(void)
{
    int ret;

    ret = gpio_request(GPIO_PIN, "led_gpio");
    if (ret < 0) {
        printk(KERN_INFO "Failed to request GPIO
");
        return ret;
    }

    gpio_direction_output(GPIO_PIN, 0);

    major_number = register_chrdev(0, DEVICE_NAME, &fops);
    if (major_number < 0) {
        printk(KERN_INFO "Failed to register device
");
        gpio_free(GPIO_PIN);
        return major_number;
    }

    led_class = class_create(THIS_MODULE, DEVICE_NAME);
    if (IS_ERR(led_class)) {
        unregister_chrdev(major_number, DEVICE_NAME);
        gpio_free(GPIO_PIN);
        printk(KERN_INFO "Failed to create class
");
        return PTR_ERR(led_class);
    }

    led_device = device_create(led_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
    if (IS_ERR(led_device)) {
        class_destroy(led_class);
        unregister_chrdev(major_number, DEVICE_NAME);
        gpio_free(GPIO_PIN);
        printk(KERN_INFO "Failed to create device
");
        return PTR_ERR(led_device);
    }

    printk(KERN_INFO "LED driver loaded
");
    return 0;
}

static void __exit led_exit(void)
{
    device_destroy(led_class, MKDEV(major_number, 0));
    class_destroy(led_class);
    unregister_chrdev(major_number, DEVICE_NAME);
    gpio_free(GPIO_PIN);
    printk(KERN_INFO "LED driver unloaded
");
}

module_init(led_init);
module_exit(led_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple LED driver");

obj-m += led_driver.o

all:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

sudo insmod led_driver.ko

sudo rmmod led_driver

sudo chmod 666 /dev/led_driver
echo 1 > /dev/led_driver # 打开LED
echo 0 > /dev/led_driver # 关闭LED