mtd_debug 命令源码

mtd_debug 命令是用于调试MTD驱动的命令，其源码可以在Linux内核源码中找到。具体路径为：drivers/mtd/tests/mtd_debug.c。

以下是 mtd_debug 命令的源码：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>
#include <linux/mtd/partitions.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <linux/mutex.h>
#include <linux/ctype.h>

static char mtd_buf[4096];
static int mtd_buf_size;

static ssize_t mtd_debug_read(struct file *file, char __user *buf,
                  size_t count, loff_t *ppos)
{
    int ret;

    if (*ppos >= mtd_buf_size)
        return 0;
    if (count > mtd_buf_size - *ppos)
        count = mtd_buf_size - *ppos;
    ret = copy_to_user(buf, mtd_buf + *ppos, count);
    if (ret)
        return -EFAULT;
    *ppos += count;
    return count;
}

static ssize_t mtd_debug_write(struct file *file, const char __user *buf,
                   size_t count, loff_t *ppos)
{
    int ret;

    if (count >= sizeof(mtd_buf))
        return -EINVAL;

    ret = copy_from_user(mtd_buf, buf, count);
    if (ret)
        return -EFAULT;
    mtd_buf_size = count;
    return count;
}

static const struct file_operations mtd_debug_fops = {
    .owner = THIS_MODULE,
    .read = mtd_debug_read,
    .write = mtd_debug_write,
};

static struct tty_driver *mtd_debug_tty_driver = NULL;

static int mtd_debug_open(struct inode *inode, struct file *file)
{
    if (!try_module_get(THIS_MODULE))
        return -ENODEV;

    file->private_data = mtd_debug_tty_driver->driver_state;
    return tty_open(inode, file);
}

static void mtd_debug_close(struct tty_struct *tty, struct file *file)
{
    tty_driver_flush_buffer(tty);
    module_put(THIS_MODULE);
    tty_close(tty, file);
}

static int mtd_debug_write_room(struct tty_struct *tty)
{
    return 65536;
}

static int mtd_debug_put_char(struct tty_struct *tty, unsigned char ch)
{
    if (mtd_buf_size >= sizeof(mtd_buf))
        return 0;
    mtd_buf[mtd_buf_size++] = ch;
    return 1;
}

static struct tty_operations mtd_debug_tty_ops = {
    .open = mtd_debug_open,
    .close = mtd_debug_close,
    .write_room = mtd_debug_write_room,
    .put_char = mtd_debug_put_char,
};

static struct tty_driver *mtd_debug_init_tty_driver(void)
{
    struct tty_driver *driver;

    driver = alloc_tty_driver(1);
    if (!driver)
        return NULL;
    driver->owner = THIS_MODULE;
    driver->driver_name = "mtd_debug";
    driver->name = "mtd_debug";
    driver->type = TTY_DRIVER_TYPE_SERIAL;
    driver->subtype = SERIAL_TYPE_NORMAL;
    driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
    tty_set_operations(driver, &mtd_debug_tty_ops);
    driver->init_termios = tty_std_termios;
    driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
    tty_register_driver(driver);
    return driver;
}

static void mtd_debug_exit_tty_driver(struct tty_driver *driver)
{
    tty_unregister_driver(driver);
    put_tty_driver(driver);
}

static int __init mtd_debug_init(void)
{
    dev_t dev;
    int ret;

    dev = MKDEV(0, 0);
    ret = register_chrdev_region(dev, 1, "mtd_debug");
    if (ret) {
        printk(KERN_ERR "mtd_debug: failed to register chrdev region\n");
        return ret;
    }

    mtd_debug_tty_driver = mtd_debug_init_tty_driver();
    if (!mtd_debug_tty_driver) {
        printk(KERN_ERR "mtd_debug: failed to init tty driver\n");
        unregister_chrdev_region(dev, 1);
        return -ENOMEM;
    }

    cdev_init(&mtd_debug_tty_driver->cdev, &mtd_debug_fops);
    mtd_debug_tty_driver->cdev.owner = THIS_MODULE;
    ret = cdev_add(&mtd_debug_tty_driver->cdev, dev, 1);
    if (ret) {
        printk(KERN_ERR "mtd_debug: failed to add cdev\n");
        mtd_debug_exit_tty_driver(mtd_debug_tty_driver);
        unregister_chrdev_region(dev, 1);
        return ret;
    }

    printk(KERN_INFO "mtd_debug: tty driver registered\n");
    return 0;
}

static void __exit mtd_debug_exit(void)
{
    dev_t dev;

    dev = MKDEV(0, 0);
    cdev_del(&mtd_debug_tty_driver->cdev);
    mtd_debug_exit_tty_driver(mtd_debug_tty_driver);
    unregister_chrdev_region(dev, 1);
    printk(KERN_INFO "mtd_debug: tty driver unregistered\n");
}

module_init(mtd_debug_init);
module_exit(mtd_debug_exit);

MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
MODULE_DESCRIPTION("MTD debug console");
MODULE_LICENSE("GPL");

该代码定义了一个字符设备，用于在调试MTD驱动时，查看和修改MTD缓冲区中的数据。同时，该代码还定义了一个 tty 驱动，将缓冲区中的数据输出到终端。用户可以通过在终端中输入和输出数据，对 MTd 缓冲区进行读写，从而进行调试。