imx6ull hello驱动代码分享

#include 
#include 
#include 
#include 
#include 

#define DEVICE_NAME "hello"
#define EXAMPLE_MSG "Hello, World!\n"
#define MSG_BUFFER_LEN 15

static int major;
static char msg_buffer[MSG_BUFFER_LEN];
static char *msg_ptr;

static int device_open(struct inode *inode, struct file *file)
{
    try_module_get(THIS_MODULE);
    msg_ptr = EXAMPLE_MSG;
    return 0;
}

static int device_release(struct inode *inode, struct file *file)
{
    module_put(THIS_MODULE);
    return 0;
}

static ssize_t device_read(struct file *filp, char *buffer, size_t length, loff_t *offset)
{
    int bytes_read = 0;
    if (*msg_ptr == 0)
        return 0;
    while (length && *msg_ptr) {
        put_user(*(msg_ptr++), buffer++);
        length--;
        bytes_read++;
    }
    return bytes_read;
}

static ssize_t device_write(struct file *filp, const char *buff, size_t len, loff_t *off)
{
    printk(KERN_ALERT "This operation is not supported.\n");
    return -EINVAL;
}

static struct file_operations fops = {
    .read = device_read,
    .write = device_write,
    .open = device_open,
    .release = device_release,
};

static int __init hello_init(void)
{
    major = register_chrdev(0, DEVICE_NAME, &fops);
    if (major < 0) {
        printk(KERN_ALERT "Registering char device failed with %d\n", major);
        return major;
    }
    printk(KERN_INFO "I was assigned major number %d. To talk to\n", major);
    printk(KERN_INFO "the driver, create a dev file with\n");
    printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, major);
    return 0;
}

static void __exit hello_exit(void)
{
    unregister_chrdev(major, DEVICE_NAME);
    printk(KERN_INFO "Goodbye, World!\n");
}

module_init(hello_init);
module_exit(hello_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("ChatGPT");
MODULE_DESCRIPTION("A simple example Linux module.");
MODULE_VERSION("0.01");