linux 串口驱动

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/serial_core.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/slab.h>

#define DRIVER_NAME "my_serial_driver"

static struct tty_driver *my_tty_driver;

// 打开串口的回调函数
static int my_serial_open(struct tty_struct *tty, struct file *filp)
{
    printk(KERN_INFO "Serial port opened\n");
    return 0;
}

// 关闭串口的回调函数
static void my_serial_close(struct tty_struct *tty, struct file *filp)
{
    printk(KERN_INFO "Serial port closed\n");
}

// 写入数据到串口的回调函数
static int my_serial_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
    int i;
    for (i = 0; i < count; i++) {
        // 模拟发送数据
        printk(KERN_INFO "Sending byte: %02x\n", buf[i]);
    }
    return count;
}

// 读取串口数据的回调函数
static int my_serial_read(struct tty_struct *tty, struct file *file, unsigned char *buf, unsigned int nr)
{
    // 模拟接收数据
    printk(KERN_INFO "Receiving data...\n");
    return 0;
}

static struct tty_operations serial_ops = {
    .open = my_serial_open,
    .close = my_serial_close,
    .write = my_serial_write,
    .read = my_serial_read,
};

static int __init my_serial_init(void)
{
    int ret;

    my_tty_driver = alloc_tty_driver(1);
    if (!my_tty_driver) {
        return -ENOMEM;
    }

    my_tty_driver->owner = THIS_MODULE;
    my_tty_driver->driver_name = DRIVER_NAME;
    my_tty_driver->name = "ttyS";
    my_tty_driver->major = TTY_MAJOR;
    my_tty_driver->minor_start = 64;
    my_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
    my_tty_driver->subtype = SERIAL_TYPE_NORMAL;
    my_tty_driver->init_termios = tty_std_termios;
    my_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;

    tty_set_operations(my_tty_driver, &serial_ops);

    ret = tty_register_driver(my_tty_driver);
    if (ret) {
        put_tty_driver(my_tty_driver);
        return ret;
    }

    printk(KERN_INFO "Serial driver loaded\n");
    return 0;
}

static void __exit my_serial_exit(void)
{
    tty_unregister_driver(my_tty_driver);
    put_tty_driver(my_tty_driver);
    printk(KERN_INFO "Serial driver unloaded\n");
}

module_init(my_serial_init);
module_exit(my_serial_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple Linux serial driver example");

解释说明

1. 模块初始化和清理:

   • my_serial_init 函数用于初始化驱动程序，分配并注册TTY驱动。
   • my_serial_exit 函数用于清理和注销TTY驱动。

2. TTY操作回调函数:

   • my_serial_open: 当打开串口时调用，打印一条信息表示串口已打开。
   • my_serial_close: 当关闭串口时调用，打印一条信息表示串口已关闭。
   • my_serial_write: 当写入数据到串口时调用，模拟发送数据并打印每个字节。
   • my_serial_read: 当从串口读取数据时调用，模拟接收数据并打印一条信息。

3. TTY驱动结构体:

   • my_tty_driver 是一个TTY驱动结构体，包含了驱动的属性和操作。
   • serial_ops 包含了TTY操作的回调函数指针。

4. 模块元数据:

   • MODULE_LICENSE, MODULE_AUTHOR, 和 MODULE_DESCRIPTION 定义了模块的许可证、作者和描述信息。