Message-Id: <45DC9EA0.000007.11000@webmail18.yandex.ru>
Date:	Wed, 21 Feb 2007 22:33:52 +0300 (MSK)
From:	"Mockern" <Mockern@...dex.ru>
To:	lsorense@...lub.uwaterloo.ca
Cc:	linux-kernel@...r.kernel.org
Subject: Re: cat problem in tiny_tty driver (the source included)

Thank you very much for you help.

BTW, for cat < /dev/my_tty1 can see here something wrong?
as I understand tiny_timer function sends data to tty level
by calling tty_flip_buffer_push(tty).

Is this enough to support cat < /dev/my_tty1?


>On Wed, Feb 21, 2007 at 06:03:16PM +0300, Mockern wrote:
>> I tried to check cat operations for tiny_tty driver from LDD book. 
>> 
>> What is wrong with cat operation here?
>> 
>> Here is the output from strace cat hello > /dev/my_tty1
>> 
>> root@...y:/home# strace cat hello > /dev/my_tty1
>> execve("/bin/cat", ["cat", "hello"], [/* 12 vars */]) = 0
>> brk(0)                                  = 0x7d000
>> open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or directory)
>> open("/etc/ld.so.cache", O_RDONLY)      = 3
>> fstat64(3, {st_mode=S_IFREG|0644, st_size=5664, ...}) = 0
>> old_mmap(NULL, 5664, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40017000
>> close(3)                                = 0
>> open("/lib/libm.so.6", O_RDONLY)        = 3
>> read(3, "\177ELF\1\1\1a\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\250B\0\000"..., 512) = 51
>> 2
>> fstat64(3, {st_mode=S_IFREG|0755, st_size=480324, ...}) = 0
>> old_mmap(NULL, 506412, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x40020000
>> mprotect(0x40093000, 35372, PROT_NONE)  = 0
>> old_mmap(0x40098000, 16384, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x70
>> 000) = 0x40098000
>> close(3)                                = 0
>> open("/lib/libcrypt.so.1", O_RDONLY)    = 3
>> read(3, "\177ELF\1\1\1a\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\260\10\0"..., 512) = 512
>> fstat64(3, {st_mode=S_IFREG|0755, st_size=19940, ...}) = 0
>> old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0
>> x40019000
>> old_mmap(NULL, 211220, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x4009c000
>> mprotect(0x400a1000, 190740, PROT_NONE) = 0
>> old_mmap(0x400a4000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0) =
>>  0x400a4000
>> old_mmap(0x400a9000, 157972, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANO
>> NYMOUS, -1, 0) = 0x400a9000
>> close(3)                                = 0
>> open("/lib/libc.so.6", O_RDONLY)        = 3
>> read(3, "\177ELF\1\1\1a\0\0\0\0\0\0\0\0\3\0(\0\1\0\0\0\330p\1\000"..., 512) = 51
>> 2
>> fstat64(3, {st_mode=S_IFREG|0755, st_size=1240024, ...}) = 0
>> old_mmap(NULL, 1257088, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x400d0000
>> mprotect(0x401f5000, 56960, PROT_NONE)  = 0
>> old_mmap(0x401f8000, 36864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x12
>> 0000) = 0x401f8000
>> old_mmap(0x40201000, 7808, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONY
>> MOUS, -1, 0) = 0x40201000
>> close(3)                                = 0
>> munmap(0x40017000, 5664)                = 0
>> getuid32()                              = 0
>> getgid32()                              = 0
>> setgid32(0)                             = 0
>> setuid32(0)                             = 0
>> brk(0)                                  = 0x7d000
>> brk(0x9e000)                            = 0x9e000
>> brk(0)                                  = 0x9e000
>> open("hello", O_RDONLY)                 = 3
>> read(3, "123456789", 8192)              = 9
>> write(1, "123456789", 9)                = -1 EINVAL (Invalid argument)//??????????
>> write(2, "cat: ", 5cat: )                    = 5
>> write(2, "Write Error", 11Write Error)             = 11
>> write(2, ": Invalid argument\n", 19: Invalid argument
>> )    = 19
>> close(3)                                = 0
>> io_submit(0, 0x40200164, 0 <unfinished ... exit status 0>
>> Process 1432 detached
>> root@...y:/home#
>> 
>> ------------------------------------------------------------------------------------
>> 
>> /*
>>  * Tiny TTY driver
>>  *
>>  * Copyright (C) 2002-2004 Greg Kroah-Hartman (greg@...ah.com)
>>  *
>>  *	This program is free software; you can redistribute it and/or modify
>>  *	it under the terms of the GNU General Public License as published by
>>  *	the Free Software Foundation, version 2 of the License.
>>  *
>>  * This driver shows how to create a minimal tty driver.  It does not rely on
>>  * any backing hardware, but creates a timer that emulates data being received
>>  * from some kind of hardware.
>>  */
>> 
>> #include <linux/config.h>
>> #include <linux/kernel.h>
>> #include <linux/errno.h>
>> #include <linux/init.h>
>> #include <linux/module.h>
>> #include <linux/slab.h>
>> #include <linux/wait.h>
>> #include <linux/tty.h>
>> #include <linux/tty_driver.h>
>> #include <linux/tty_flip.h>
>> #include <linux/serial.h>
>> #include <asm/uaccess.h>
>> 
>> 
>> #define DRIVER_VERSION "v2.0"
>> #define DRIVER_AUTHOR "Greg Kroah-Hartman <greg@...ah.com>"
>> #define DRIVER_DESC "Tiny TTY driver"
>> 
>> /* Module information */
>> MODULE_AUTHOR( DRIVER_AUTHOR );
>> MODULE_DESCRIPTION( DRIVER_DESC );
>> MODULE_LICENSE("GPL");
>> 
>> #define DELAY_TIME		HZ * 2	/* 2 seconds per character */
>> #define TINY_DATA_CHARACTER	't'
>> 
>> #define TINY_TTY_MAJOR		240	/* experimental range */
>> #define TINY_TTY_MINORS		4	/* only have 4 devices */
>> 
>> struct tiny_serial {
>> 	struct tty_struct	*tty;		/* pointer to the tty for this device */
>> 	int			open_count;	/* number of times this port has been opened */
>> 	struct semaphore	sem;		/* locks this structure */
>> 	struct timer_list	*timer;
>> 
>> 	/* for tiocmget and tiocmset functions */
>> 	int			msr;		/* MSR shadow */
>> 	int			mcr;		/* MCR shadow */
>> 
>> 	/* for ioctl fun */
>> 	struct serial_struct	serial;
>> 	wait_queue_head_t	wait;
>> 	struct async_icount	icount;
>> };
>> 
>> static struct tiny_serial *tiny_table[TINY_TTY_MINORS];	/* initially all NULL */
>> 
>> 
>> static void tiny_timer(unsigned long timer_data)
>> {
>> 	struct tiny_serial *tiny = (struct tiny_serial *)timer_data;
>> 	struct tty_struct *tty;
>> 	int i;
>> 	char data[1] = {TINY_DATA_CHARACTER};
>> 	int data_size = 1;
>> 
>> 	if (!tiny)
>> 		return;
>> 
>> 	tty = tiny->tty;
>> 
>> 	/* send the data to the tty layer for users to read.  This doesn't
>> 	 * actually push the data through unless tty->low_latency is set */
>> 	for (i = 0; i < data_size; ++i) {
>> 		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
>> 			tty_flip_buffer_push(tty);
>> 		tty_insert_flip_char(tty, data[i], TTY_NORMAL);
>> 	}
>> 	tty_flip_buffer_push(tty);
>> 
>> 	/* resubmit the timer again */
>> 	tiny->timer->expires = jiffies + DELAY_TIME;
>> 	add_timer(tiny->timer);
>> }
>> 
>> static int tiny_open(struct tty_struct *tty, struct file *file)
>> {
>> 	struct tiny_serial *tiny;
>> 	struct timer_list *timer;
>> 	int index;
>> 
>> 	/* initialize the pointer in case something fails */
>> 	tty->driver_data = NULL;
>> 
>> 	/* get the serial object associated with this tty pointer */
>> 	index = tty->index;
>> 	tiny = tiny_table[index];
>> 	if (tiny == NULL) {
>> 		/* first time accessing this device, let's create it */
>> 		tiny = kmalloc(sizeof(*tiny), GFP_KERNEL);
>> 		if (!tiny)
>> 			return -ENOMEM;
>> 
>> 		init_MUTEX(&tiny->sem);
>> 		tiny->open_count = 0;
>> 		tiny->timer = NULL;
>> 
>> 		tiny_table[index] = tiny;
>> 	}
>> 
>> 	down(&tiny->sem);
>> 
>> 	/* save our structure within the tty structure */
>> 	tty->driver_data = tiny;
>> 	tiny->tty = tty;
>> 
>> 	++tiny->open_count;
>> 	if (tiny->open_count == 1) {
>> 		/* this is the first time this port is opened */
>> 		/* do any hardware initialization needed here */
>> 
>> 		/* create our timer and submit it */
>> 		if (!tiny->timer) {
>> 			timer = kmalloc(sizeof(*timer), GFP_KERNEL);
>> 			if (!timer) {
>> 				up(&tiny->sem);
>> 				return -ENOMEM;
>> 			}
>> 			tiny->timer = timer;
>> 		}
>> 		tiny->timer->data = (unsigned long )tiny;
>> 		tiny->timer->expires = jiffies + DELAY_TIME;
>> 		tiny->timer->function = tiny_timer;
>> 		add_timer(tiny->timer);
>> 	}
>> 
>> 	up(&tiny->sem);
>> 	return 0;
>> }
>> 
>> static void do_close(struct tiny_serial *tiny)
>> {
>> 	down(&tiny->sem);
>> 
>> 	if (!tiny->open_count) {
>> 		/* port was never opened */
>> 		goto exit;
>> 	}
>> 
>> 	--tiny->open_count;
>> 	if (tiny->open_count <= 0) {
>> 		/* The port is being closed by the last user. */
>> 		/* Do any hardware specific stuff here */
>> 
>> 		/* shut down our timer */
>> 		del_timer(tiny->timer);
>> 	}
>> exit:
>> 	up(&tiny->sem);
>> }
>> 
>> static void tiny_close(struct tty_struct *tty, struct file *file)
>> {
>> 	struct tiny_serial *tiny = tty->driver_data;
>> 
>> 	if (tiny)
>> 		do_close(tiny);
>> }
>> 
>> static int tiny_write(struct tty_struct *tty, const unsigned char *buffer, int count)
>> {
>> 	struct tiny_serial *tiny = tty->driver_data;
>> 	int i;
>> 	int retval = -EINVAL;
>
>Here you set retval to EINVAL.
>
>> 	if (!tiny)
>> 		return -ENODEV;
>> 
>> 	down(&tiny->sem);
>> 
>> 	if (!tiny->open_count)
>> 		/* port was not opened */
>> 		goto exit;
>> 
>> 	/* fake sending the data out a hardware port by
>> 	 * writing it to the kernel debug log.
>> 	 */
>> 	printk(KERN_DEBUG "%s - ", __FUNCTION__);
>> 	for (i = 0; i < count; ++i)
>> 		printk("%02x ", buffer[i]);
>> 	printk("\n");
>> 
>> exit:
>> 	up(&tiny->sem);
>> 	return retval;
>
>Now you return it.  You never changed it.  No wonder cat receives
>'EINVAL' as a response to its write request.  This is obviously not what
>you intended.
>
>> }
>> 
>> static int tiny_write_room(struct tty_struct *tty)
>> {
>> 	struct tiny_serial *tiny = tty->driver_data;
>> 	int room = -EINVAL;
>> 
>> 	if (!tiny)
>> 		return -ENODEV;
>> 
>> 	down(&tiny->sem);
>> 
>> 	if (!tiny->open_count) {
>> 		/* port was not opened */
>> 		goto exit;
>> 	}
>> 
>> 	/* calculate how much room is left in the device */
>> 	room = 255;
>> 
>> exit:
>> 	up(&tiny->sem);
>> 	return room;
>> }
>> 
>> #define RELEVANT_IFLAG(iflag) ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
>> 
>> static void tiny_set_termios(struct tty_struct *tty, struct termios *old_termios)
>> {
>> 	unsigned int cflag;
>> 
>> 	cflag = tty->termios->c_cflag;
>> 
>> 	/* check that they really want us to change something */
>> 	if (old_termios) {
>> 		if ((cflag == old_termios->c_cflag) &&
>> 		    (RELEVANT_IFLAG(tty->termios->c_iflag) ==
>> 		     RELEVANT_IFLAG(old_termios->c_iflag))) {
>> 			printk(KERN_DEBUG " - nothing to change...\n");
>> 			return;
>> 		}
>> 	}
>> 
>> 	/* get the byte size */
>> 	switch (cflag & CSIZE) {
>> 		case CS5:
>> 			printk(KERN_DEBUG " - data bits = 5\n");
>> 			break;
>> 		case CS6:
>> 			printk(KERN_DEBUG " - data bits = 6\n");
>> 			break;
>> 		case CS7:
>> 			printk(KERN_DEBUG " - data bits = 7\n");
>> 			break;
>> 		default:
>> 		case CS8:
>> 			printk(KERN_DEBUG " - data bits = 8\n");
>> 			break;
>> 	}
>> 
>> 	/* determine the parity */
>> 	if (cflag & PARENB)
>> 		if (cflag & PARODD)
>> 			printk(KERN_DEBUG " - parity = odd\n");
>> 		else
>> 			printk(KERN_DEBUG " - parity = even\n");
>> 	else
>> 		printk(KERN_DEBUG " - parity = none\n");
>> 
>> 	/* figure out the stop bits requested */
>> 	if (cflag & CSTOPB)
>> 		printk(KERN_DEBUG " - stop bits = 2\n");
>> 	else
>> 		printk(KERN_DEBUG " - stop bits = 1\n");
>> 
>> 	/* figure out the hardware flow control settings */
>> 	if (cflag & CRTSCTS)
>> 		printk(KERN_DEBUG " - RTS/CTS is enabled\n");
>> 	else
>> 		printk(KERN_DEBUG " - RTS/CTS is disabled\n");
>> 
>> 	/* determine software flow control */
>> 	/* if we are implementing XON/XOFF, set the start and
>> 	 * stop character in the device */
>> 	if (I_IXOFF(tty) || I_IXON(tty)) {
>> 		unsigned char stop_char  = STOP_CHAR(tty);
>> 		unsigned char start_char = START_CHAR(tty);
>> 
>> 		/* if we are implementing INBOUND XON/XOFF */
>> 		if (I_IXOFF(tty))
>> 			printk(KERN_DEBUG " - INBOUND XON/XOFF is enabled, "
>> 				"XON = %2x, XOFF = %2x", start_char, stop_char);
>> 		else
>> 			printk(KERN_DEBUG" - INBOUND XON/XOFF is disabled");
>> 
>> 		/* if we are implementing OUTBOUND XON/XOFF */
>> 		if (I_IXON(tty))
>> 			printk(KERN_DEBUG" - OUTBOUND XON/XOFF is enabled, "
>> 				"XON = %2x, XOFF = %2x", start_char, stop_char);
>> 		else
>> 			printk(KERN_DEBUG" - OUTBOUND XON/XOFF is disabled");
>> 	}
>> 
>> 	/* get the baud rate wanted */
>> 	printk(KERN_DEBUG " - baud rate = %d", tty_get_baud_rate(tty));
>> }
>> 
>> /* Our fake UART values */
>> #define MCR_DTR		0x01
>> #define MCR_RTS		0x02
>> #define MCR_LOOP	0x04
>> #define MSR_CTS		0x08
>> #define MSR_CD		0x10
>> #define MSR_RI		0x20
>> #define MSR_DSR		0x40
>> 
>> static int tiny_tiocmget(struct tty_struct *tty, struct file *file)
>> {
>> 	struct tiny_serial *tiny = tty->driver_data;
>> 
>> 	unsigned int result = 0;
>> 	unsigned int msr = tiny->msr;
>> 	unsigned int mcr = tiny->mcr;
>> 
>> 	result = ((mcr & MCR_DTR)  ? TIOCM_DTR  : 0) |	/* DTR is set */
>>              ((mcr & MCR_RTS)  ? TIOCM_RTS  : 0) |	/* RTS is set */
>>              ((mcr & MCR_LOOP) ? TIOCM_LOOP : 0) |	/* LOOP is set */
>>              ((msr & MSR_CTS)  ? TIOCM_CTS  : 0) |	/* CTS is set */
>>              ((msr & MSR_CD)   ? TIOCM_CAR  : 0) |	/* Carrier detect is set*/
>>              ((msr & MSR_RI)   ? TIOCM_RI   : 0) |	/* Ring Indicator is set */
>>              ((msr & MSR_DSR)  ? TIOCM_DSR  : 0);	/* DSR is set */
>> 
>> 	return result;
>> }
>> 
>> static int tiny_tiocmset(struct tty_struct *tty, struct file *file, unsigned int set, unsigned int clear)
>> {
>> 	struct tiny_serial *tiny = tty->driver_data;
>> 	unsigned int mcr = tiny->mcr;
>> 
>> 	if (set & TIOCM_RTS)
>> 		mcr |= MCR_RTS;
>> 	if (set & TIOCM_DTR)
>> 		mcr |= MCR_RTS;
>> 
>> 	if (clear & TIOCM_RTS)
>> 		mcr &= ~MCR_RTS;
>> 	if (clear & TIOCM_DTR)
>> 		mcr &= ~MCR_RTS;
>> 
>> 	/* set the new MCR value in the device */
>> 	tiny->mcr = mcr;
>> 	return 0;
>> }
>> 
>> static int tiny_read_proc(char *page, char **start, off_t off, int count,
>>                           int *eof, void *data)
>> {
>> 	struct tiny_serial *tiny;
>> 	off_t begin = 0;
>> 	int length = 0;
>> 	int i;
>> 
>> 	length += sprintf(page, "tinyserinfo:1.0 driver:%s\n", DRIVER_VERSION);
>> 	for (i = 0; i < TINY_TTY_MINORS && length < PAGE_SIZE; ++i) {
>> 		tiny = tiny_table[i];
>> 		if (tiny == NULL)
>> 			continue;
>> 
>> 		length += sprintf(page+length, "%d\n", i);
>> 		if ((length + begin) > (off + count))
>> 			goto done;
>> 		if ((length + begin) < off) {
>> 			begin += length;
>> 			length = 0;
>> 		}
>> 	}
>> 	*eof = 1;
>> done:
>> 	if (off >= (length + begin))
>> 		return 0;
>> 	*start = page + (off-begin);
>> 	return (count < begin+length-off) ? count : begin + length-off;
>> }
>> 
>> #define tiny_ioctl tiny_ioctl_tiocgserial
>> static int tiny_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
>> {
>> 	struct tiny_serial *tiny = tty->driver_data;
>> 
>> 	if (cmd == TIOCGSERIAL) {
>> 		struct serial_struct tmp;
>> 
>> 		if (!arg)
>> 			return -EFAULT;
>> 
>> 		memset(&tmp, 0, sizeof(tmp));
>> 
>> 		tmp.type		= tiny->serial.type;
>> 		tmp.line		= tiny->serial.line;
>> 		tmp.port		= tiny->serial.port;
>> 		tmp.irq			= tiny->serial.irq;
>> 		tmp.flags		= ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ;
>> 		tmp.xmit_fifo_size	= tiny->serial.xmit_fifo_size;
>> 		tmp.baud_base		= tiny->serial.baud_base;
>> 		tmp.close_delay		= 5*HZ;
>> 		tmp.closing_wait	= 30*HZ;
>> 		tmp.custom_divisor	= tiny->serial.custom_divisor;
>> 		tmp.hub6		= tiny->serial.hub6;
>> 		tmp.io_type		= tiny->serial.io_type;
>> 
>> 		if (copy_to_user((void __user *)arg, &tmp, sizeof(struct serial_struct)))
>> 			return -EFAULT;
>> 		return 0;
>> 	}
>> 	return -ENOIOCTLCMD;
>> }
>> #undef tiny_ioctl
>> 
>> #define tiny_ioctl tiny_ioctl_tiocmiwait
>> static int tiny_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
>> {
>> 	struct tiny_serial *tiny = tty->driver_data;
>> 
>> 	if (cmd == TIOCMIWAIT) {
>> 		DECLARE_WAITQUEUE(wait, current);
>> 		struct async_icount cnow;
>> 		struct async_icount cprev;
>> 
>> 		cprev = tiny->icount;
>> 		while (1) {
>> 			add_wait_queue(&tiny->wait, &wait);
>> 			set_current_state(TASK_INTERRUPTIBLE);
>> 			schedule();
>> 			remove_wait_queue(&tiny->wait, &wait);
>> 
>> 			/* see if a signal woke us up */
>> 			if (signal_pending(current))
>> 				return -ERESTARTSYS;
>> 
>> 			cnow = tiny->icount;
>> 			if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
>> 			    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts)
>> 				return -EIO; /* no change => error */
>> 			if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
>> 			    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
>> 			    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
>> 			    ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts)) ) {
>> 				return 0;
>> 			}
>> 			cprev = cnow;
>> 		}
>> 
>> 	}
>> 	return -ENOIOCTLCMD;
>> }
>> #undef tiny_ioctl
>> 
>> #define tiny_ioctl tiny_ioctl_tiocgicount
>> static int tiny_ioctl(struct tty_struct *tty, struct file *file,
>>                       unsigned int cmd, unsigned long arg)
>> {
>> 	struct tiny_serial *tiny = tty->driver_data;
>> 
>> 	if (cmd == TIOCGICOUNT) {
>> 		struct async_icount cnow = tiny->icount;
>> 		struct serial_icounter_struct icount;
>> 
>> 		icount.cts	= cnow.cts;
>> 		icount.dsr	= cnow.dsr;
>> 		icount.rng	= cnow.rng;
>> 		icount.dcd	= cnow.dcd;
>> 		icount.rx	= cnow.rx;
>> 		icount.tx	= cnow.tx;
>> 		icount.frame	= cnow.frame;
>> 		icount.overrun	= cnow.overrun;
>> 		icount.parity	= cnow.parity;
>> 		icount.brk	= cnow.brk;
>> 		icount.buf_overrun = cnow.buf_overrun;
>> 
>> 		if (copy_to_user((void __user *)arg, &icount, sizeof(icount)))
>> 			return -EFAULT;
>> 		return 0;
>> 	}
>> 	return -ENOIOCTLCMD;
>> }
>> #undef tiny_ioctl
>> 
>> /* the real tiny_ioctl function.  The above is done to get the small functions in the book */
>> static int tiny_ioctl(struct tty_struct *tty, struct file *file,
>>                       unsigned int cmd, unsigned long arg)
>> {
>> 	switch (cmd) {
>> 	case TIOCGSERIAL:
>> 		return tiny_ioctl_tiocgserial(tty, file, cmd, arg);
>> 	case TIOCMIWAIT:
>> 		return tiny_ioctl_tiocmiwait(tty, file, cmd, arg);
>> 	case TIOCGICOUNT:
>> 		return tiny_ioctl_tiocgicount(tty, file, cmd, arg);
>> 	}
>> 
>> 	return -ENOIOCTLCMD;
>> }
>> 
>> static struct tty_operations serial_ops = {
>> 	.open = tiny_open,
>> 	.close = tiny_close,
>> 	.write = tiny_write,
>> 	.write_room = tiny_write_room,
>> 	.set_termios = tiny_set_termios,
>> };
>> 
>> static struct tty_driver *tiny_tty_driver;
>> 
>> static int __init tiny_init(void)
>> {
>> 	int retval;
>> 	int i;
>> 
>> 	/* allocate the tty driver */
>> 	tiny_tty_driver = alloc_tty_driver(TINY_TTY_MINORS);
>> 	if (!tiny_tty_driver)
>> 		return -ENOMEM;
>> 
>> 	/* initialize the tty driver */
>> 	tiny_tty_driver->owner = THIS_MODULE;
>> 	tiny_tty_driver->driver_name = "tiny_tty";
>> 	tiny_tty_driver->name = "ttty";
>> 	tiny_tty_driver->devfs_name = "tts/ttty%d";
>> 	tiny_tty_driver->major = TINY_TTY_MAJOR,
>> 	tiny_tty_driver->type = TTY_DRIVER_TYPE_SERIAL,
>> 	tiny_tty_driver->subtype = SERIAL_TYPE_NORMAL,
>> 	tiny_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_NO_DEVFS,
>> 	tiny_tty_driver->init_termios = tty_std_termios;
>> 	tiny_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
>> 	tty_set_operations(tiny_tty_driver, &serial_ops);
>> 
>> 	/* hack to make the book purty, yet still use these functions in the
>> 	 * real driver.  They really should be set up in the serial_ops
>> 	 * structure above... */
>> 	tiny_tty_driver->read_proc = tiny_read_proc;
>> 	tiny_tty_driver->tiocmget = tiny_tiocmget;
>> 	tiny_tty_driver->tiocmset = tiny_tiocmset;
>> 	tiny_tty_driver->ioctl = tiny_ioctl;
>> 
>> 	/* register the tty driver */
>> 	retval = tty_register_driver(tiny_tty_driver);
>> 	if (retval) {
>> 		printk(KERN_ERR "failed to register tiny tty driver");
>> 		put_tty_driver(tiny_tty_driver);
>> 		return retval;
>> 	}
>> 
>> 	for (i = 0; i < TINY_TTY_MINORS; ++i)
>> 		tty_register_device(tiny_tty_driver, i, NULL);
>> 
>> 	printk(KERN_INFO DRIVER_DESC " " DRIVER_VERSION);
>> 	return retval;
>> }
>> 
>> static void __exit tiny_exit(void)
>> {
>> 	struct tiny_serial *tiny;
>> 	int i;
>> 
>> 	for (i = 0; i < TINY_TTY_MINORS; ++i)
>> 		tty_unregister_device(tiny_tty_driver, i);
>> 	tty_unregister_driver(tiny_tty_driver);
>> 
>> 	/* shut down all of the timers and free the memory */
>> 	for (i = 0; i < TINY_TTY_MINORS; ++i) {
>> 		tiny = tiny_table[i];
>> 		if (tiny) {
>> 			/* close the port */
>> 			while (tiny->open_count)
>> 				do_close(tiny);
>> 
>> 			/* shut down our timer and free the memory */
>> 			del_timer(tiny->timer);
>> 			kfree(tiny->timer);
>> 			kfree(tiny);
>> 			tiny_table[i] = NULL;
>> 		}
>> 	}
>> }
>> 
>> module_init(tiny_init);
>> module_exit(tiny_exit);
>
>--
>Len Sorensen
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