linux+驱动读写寄存器

#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 REG_ADDR 0x12345678 // 假设的设备寄存器地址

static int major_number;
static void __iomem *reg_base;

static ssize_t my_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
{
    u32 value = ioread32(reg_base);
    if (copy_to_user(buf, &value, sizeof(value)))
        return -EFAULT;
    return sizeof(value);
}

static ssize_t my_write(struct file *filp, const char __user *buf, size_t count, loff_t *f_pos)
{
    u32 value;
    if (copy_from_user(&value, buf, sizeof(value)))
        return -EFAULT;
    iowrite32(value, reg_base);
    return sizeof(value);
}

static struct file_operations fops = {
    .owner = THIS_MODULE,
    .read = my_read,
    .write = my_write,
};

static int __init my_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;
    }
    printk(KERN_INFO "Device registered with major number %d
", major_number);

    // 假设我们已经知道设备的内存映射地址
    reg_base = ioremap(REG_ADDR, 4); // 映射4个字节
    if (!reg_base) {
        printk(KERN_ALERT "Failed to map registers
");
        unregister_chrdev(major_number, DEVICE_NAME);
        return -ENOMEM;
    }
    printk(KERN_INFO "Registers mapped successfully
");
    return 0;
}

static void __exit my_exit(void)
{
    iounmap(reg_base);
    unregister_chrdev(major_number, DEVICE_NAME);
    printk(KERN_INFO "Device unregistered
");
}

module_init(my_init);
module_exit(my_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple device driver for register read/write");