linux led驱动实例

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

#define DEVICE_NAME "myled"
#define CLASS_NAME "myled_class"

static int major_number;
static struct class *myled_class;
static struct device *myled_device;
static int led_gpio = 21; // GPIO pin for LED

static int myled_open(struct inode *inode, struct file *file) {
    gpio_request(led_gpio, "myled");
    gpio_direction_output(led_gpio, 0);
    return 0;
}

static int myled_release(struct inode *inode, struct file *file) {
    gpio_free(led_gpio);
    return 0;
}

static ssize_t myled_write(struct file *file, const char __user *ubuf, size_t count, loff_t *ppos) {
    char buf[1];
    if (*ppos > 0 || count > 1)
        return -EFAULT;
    if (copy_from_user(buf, ubuf, 1)) {
        printk(KERN_ALERT "Failed to copy data from user\n");
        return -EFAULT;
    }
    if (buf[0] == '1')
        gpio_set_value(led_gpio, 1);
    else
        gpio_set_value(led_gpio, 0);
    *ppos += count;
    return count;
}

static struct file_operations fops = {
    .open = myled_open,
    .release = myled_release,
    .write = myled_write,
};

static int __init myled_init(void) {
    major_number = register_chrdev(0, DEVICE_NAME, &fops);
    if (major_number < 0) {
        printk(KERN_ALERT "Failed to register a major number\n");
        return major_number;
    }
    myled_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(myled_class)) {
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "Failed to register device class\n");
        return PTR_ERR(myled_class);
    }
    myled_device = device_create(myled_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
    if (IS_ERR(myled_device)) {
        class_destroy(myled_class);
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "Failed to create the device\n");
        return PTR_ERR(myled_device);
    }
    printk(KERN_INFO "LED driver initialized successfully\n");
    return 0;
}

static void __exit myled_exit(void) {
    device_destroy(myled_class, MKDEV(major_number, 0));
    class_unregister(myled_class);
    class_destroy(myled_class);
    unregister_chrdev(major_number, DEVICE_NAME);
    printk(KERN_INFO "LED driver removed successfully\n");
}

module_init(myled_init);
module_exit(myled_exit);

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