tty 驱动学习

Makefile

KBUILD_EXTRA_SYMBOLS=/home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-3.2.0-psp04.06.00.11/am335x_evm/Module.symvers
ifneq ($(KERNELRELEASE),)
    obj-m := my_tty.o
else
    KERNELDIR ?= /home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-3.2.0-psp04.06.00.11/am335x_evm
    PWD := $(shell pwd)
default:
    $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
    cp *.ko /home/fang/ti-sdk-am335x-evm-06.00.00.00/filesystem/rootfs/test_modules
clean:
    @rm -rf *.o *.mod.c *.mod.o *.ko *.order *.symvers .*.cmd .tmp_versions
endif

my_tty.c

#include <linux/module.h>
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/kd.h>
#include <linux/slab.h>
#include <linux/major.h>
#include <linux/mm.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/vt_kern.h>
#include <linux/selection.h>
#include <linux/tiocl.h>
#include <linux/kbd_kern.h>
#include <linux/consolemap.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/pm.h>
#include <linux/font.h>
#include <linux/bitops.h>
#include <linux/notifier.h>
#include <linux/device.h>
#include <linux/io.h>
#include <asm/system.h>
#include <linux/uaccess.h>
#include <linux/kdb.h>
#include <linux/ctype.h>

static int con_open(struct tty_struct *, struct file *);
static void vc_init(struct vc_data *vc, unsigned int rows,
            unsigned int cols, int do_clear);
static void gotoxy(struct vc_data *vc, int new_x, int new_y);
static void save_cur(struct vc_data *vc);
static void reset_terminal(struct vc_data *vc, int do_clear);
static void con_flush_chars(struct tty_struct *tty);
static int set_vesa_blanking(char __user *p);
static void set_cursor(struct vc_data *vc);
static void hide_cursor(struct vc_data *vc);
static void console_callback(struct work_struct *ignored);
static void blank_screen_t(unsigned long dummy);
static void set_palette(struct vc_data *vc);


struct tty_driver *console_driver;

/*
 * /dev/ttyN handling
 */

static int con_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
    int    retval;
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
    return count;
}

static int con_put_char(struct tty_struct *tty, unsigned char ch)
{
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
    return 0;
}

static int con_chars_in_buffer(struct tty_struct *tty)
{
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
    return 0;        /* we're not buffering */
}

/*
 * con_throttle and con_unthrottle are only used for
 * paste_selection(), which has to stuff in a large number of
 * characters...
 */
static void con_throttle(struct tty_struct *tty)
{
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
}

static void con_unthrottle(struct tty_struct *tty)
{
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
}

/*
 * Allocate the console screen memory.
 */
static int con_open(struct tty_struct *tty, struct file *filp)
{
    unsigned int currcons = tty->index;
    int ret = 0;
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
    console_lock();
    console_unlock();
    return ret;
}

static void con_close(struct tty_struct *tty, struct file *filp)
{
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
    /* Nothing to do - we defer to shutdown */
}

static void con_shutdown(struct tty_struct *tty)
{
    struct vc_data *vc = tty->driver_data;
    //BUG_ON(vc == NULL);
    console_lock();
    //vc->port.tty = NULL;
    console_unlock();
    tty_shutdown(tty);
}
static int con_write_room(struct tty_struct *tty)
{
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
    if (tty->stopped)
        return 0;
    return 32768;        /* No limit, really; we're not buffering */
}
static void con_stop(struct tty_struct *tty)
{
    int console_num;
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);

}
/*
 * Turn the Scroll-Lock LED off when the console is started
 */
static void con_start(struct tty_struct *tty)
{
    int console_num;
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
}

static int vt_resize(struct tty_struct *tty, struct winsize *ws)
{
    struct vc_data *vc = tty->driver_data;
    int ret;

    console_lock();
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
    console_unlock();
    return 0;
}
static void con_flush_chars(struct tty_struct *tty)
{
    printk(" %s %s line:%d\n", __func__,__FILE__,__LINE__);
}




/*
 * We handle the console-specific ioctl's here. We allow the
 * capability to modify any console, not just the fg_console.
 */
int vt_ioctl(struct tty_struct *tty,
         unsigned int cmd, unsigned long arg)
{
    return 0;
}

static const struct tty_operations con_ops = {
    .open = con_open,
    .close = con_close,
    .write = con_write,
    .write_room = con_write_room,
    .put_char = con_put_char,
    .flush_chars = con_flush_chars,
    .chars_in_buffer = con_chars_in_buffer,
    .ioctl = vt_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl = vt_compat_ioctl,
#endif
    .stop = con_stop,
    .start = con_start,
    .throttle = con_throttle,
    .unthrottle = con_unthrottle,
    .resize = vt_resize,
    .shutdown = con_shutdown
};

static struct cdev vc0_cdev;
int default_utf8 = true;
int __init mytty_init(const struct file_operations *console_fops)
{
    console_driver = alloc_tty_driver(MAX_NR_CONSOLES);
    if (!console_driver)
        panic("Couldn't allocate console driver\n");
    console_driver->owner = THIS_MODULE;
    console_driver->name = "tty_my";
    console_driver->name_base = 1;
    console_driver->major = TTY_MAJOR;
    console_driver->minor_start = 128;
    console_driver->type = TTY_DRIVER_TYPE_CONSOLE;
    console_driver->init_termios = tty_std_termios;
    if (default_utf8)
        console_driver->init_termios.c_iflag |= IUTF8;
    console_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
    tty_set_operations(console_driver, &con_ops);
    printk("console_driver ->num:%08x %s %s line:%d\n", console_driver->num,__func__,__FILE__,__LINE__);
    if (tty_register_driver(console_driver))
        panic("Couldn't register console driver\n");

    return 0;
}
static void mytty_exit(void)
{
    int i = 0;
    tty_unregister_driver(console_driver);
    for (i=0; i <console_driver->num; i++)
        tty_unregister_device(console_driver, i);
}

module_init(mytty_init);
module_exit(mytty_exit);

MODULE_LICENSE("GPL");

测试：

insmod  my_tty.ko
echo a>/dev/tty_my1
[ 165.343902] con_open /home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-modules/3.2.0/ttydriver/my_tty.c line:99
[ 165.355804] con_write_room /home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-modules/3.2.0/ttydriver/my_tty.c line:122
[ 165.368194] con_write /home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-modules/3.2.0/ttydriver/my_tty.c line:61
[ 165.380035] con_write_room /home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-modules/3.2.0/ttydriver/my_tty.c line:122
[ 165.392395] con_write /home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-modules/3.2.0/ttydriver/my_tty.c line:61
[ 165.404235] con_flush_chars /home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-modules/3.2.0/ttydriver/my_tty.c line:154
[ 165.416748] con_close /home/fang/ti-sdk-am335x-evm-06.00.00.00/board-support/linux-modules/3.2.0/ttydriver/my_tty.c line:107