linux驱动 内存读写

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

#define DEVICE_NAME "my_device"
#define CLASS_NAME "my_class"

static int major_number;
static void __iomem *mem_map;

static ssize_t device_read(struct file *filp, char __user *buffer, size_t length, loff_t *offset) {
    u32 data;
    if (*offset >= 4) {
        return 0; // End of file
    }
    data = ioread32(mem_map + *offset);
    if (copy_to_user(buffer, &data, sizeof(data))) {
        return -EFAULT;
    }
    *offset += sizeof(data);
    return sizeof(data);
}

static ssize_t device_write(struct file *filp, const char __user *buffer, size_t length, loff_t *offset) {
    u32 data;
    if (copy_from_user(&data, buffer, sizeof(data))) {
        return -EFAULT;
    }
    iowrite32(data, mem_map + *offset);
    *offset += sizeof(data);
    return sizeof(data);
}

static struct file_operations fops = {
    .read = device_read,
    .write = device_write,
};

static int __init driver_init(void) {
    major_number = register_chrdev(0, DEVICE_NAME, &fops);
    if (major_number < 0) {
        printk(KERN_ALERT "Failed to register device\n");
        return major_number;
    }
    mem_map = ioremap(0x12345678, 0x1000); // Example address and size
    if (!mem_map) {
        printk(KERN_ALERT "Failed to map memory\n");
        unregister_chrdev(major_number, DEVICE_NAME);
        return -ENOMEM;
    }
    printk(KERN_INFO "Driver loaded successfully\n");
    return 0;
}

static void __exit driver_exit(void) {
    iounmap(mem_map);
    unregister_chrdev(major_number, DEVICE_NAME);
    printk(KERN_INFO "Driver unloaded successfully\n");
}

module_init(driver_init);
module_exit(driver_exit);

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