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kernel-ark/drivers/net/irda/irtty-sir.c
Alan Cox 33f0f88f1c [PATCH] TTY layer buffering revamp 
The API and code have been through various bits of initial review by
serial driver people but they definitely need to live somewhere for a
while so the unconverted drivers can get knocked into shape, existing
drivers that have been updated can be better tuned and bugs whacked out.

This replaces the tty flip buffers with kmalloc objects in rings. In the
normal situation for an IRQ driven serial port at typical speeds the
behaviour is pretty much the same, two buffers end up allocated and the
kernel cycles between them as before.

When there are delays or at high speed we now behave far better as the
buffer pool can grow a bit rather than lose characters. This also means
that we can operate at higher speeds reliably.

For drivers that receive characters in blocks (DMA based, USB and
especially virtualisation) the layer allows a lot of driver specific
code that works around the tty layer with private secondary queues to be
removed. The IBM folks need this sort of layer, the smart serial port
people do, the virtualisers do (because a virtualised tty typically
operates at infinite speed rather than emulating 9600 baud).

Finally many drivers had invalid and unsafe attempts to avoid buffer
overflows by directly invoking tty methods extracted out of the innards
of work queue structs. These are no longer needed and all go away. That
fixes various random hangs with serial ports on overflow.

The other change in here is to optimise the receive_room path that is
used by some callers. It turns out that only one ldisc uses receive room
except asa constant and it updates it far far less than the value is
read. We thus make it a variable not a function call.

I expect the code to contain bugs due to the size alone but I'll be
watching and squashing them and feeding out new patches as it goes.

Because the buffers now dynamically expand you should only run out of
buffering when the kernel runs out of memory for real.  That means a lot of
the horrible hacks high performance drivers used to do just aren't needed any
more.

Description:

tty_insert_flip_char is an old API and continues to work as before, as does
tty_flip_buffer_push() [this is why many drivers dont need modification].  It
does now also return the number of chars inserted

There are also

tty_buffer_request_room(tty, len)

which asks for a buffer block of the length requested and returns the space
found.  This improves efficiency with hardware that knows how much to
transfer.

and tty_insert_flip_string_flags(tty, str, flags, len)

to insert a string of characters and flags

For a smart interface the usual code is

    len = tty_request_buffer_room(tty, amount_hardware_says);
    tty_insert_flip_string(tty, buffer_from_card, len);

More description!

At the moment tty buffers are attached directly to the tty.  This is causing a
lot of the problems related to tty layer locking, also problems at high speed
and also with bursty data (such as occurs in virtualised environments)

I'm working on ripping out the flip buffers and replacing them with a pool of
dynamically allocated buffers.  This allows both for old style "byte I/O"
devices and also helps virtualisation and smart devices where large blocks of
data suddenely materialise and need storing.

So far so good.  Lots of drivers reference tty->flip.*.  Several of them also
call directly and unsafely into function pointers it provides.  This will all
break.  Most drivers can use tty_insert_flip_char which can be kept as an API
but others need more.

At the moment I've added the following interfaces, if people think more will
be needed now is a good time to say

 int tty_buffer_request_room(tty, size)

Try and ensure at least size bytes are available, returns actual room (may be
zero).  At the moment it just uses the flipbuf space but that will change.
Repeated calls without characters being added are not cumulative.  (ie if you
call it with 1, 1, 1, and then 4 you'll have four characters of space.  The
other functions will also try and grow buffers in future but this will be a
more efficient way when you know block sizes.

 int tty_insert_flip_char(tty, ch, flag)

As before insert a character if there is room.  Now returns 1 for success, 0
for failure.

 int tty_insert_flip_string(tty, str, len)

Insert a block of non error characters.  Returns the number inserted.

 int tty_prepare_flip_string(tty, strptr, len)

Adjust the buffer to allow len characters to be added.  Returns a buffer
pointer in strptr and the length available.  This allows for hardware that
needs to use functions like insl or mencpy_fromio.

Signed-off-by: Alan Cox <alan@redhat.com>
Cc: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Hirokazu Takata <takata@linux-m32r.org>
Signed-off-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: John Hawkes <hawkes@sgi.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:59 -08:00

627 lines
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/*********************************************************************
*
* Filename: irtty-sir.c
* Version: 2.0
* Description: IrDA line discipline implementation
* Status: Experimental.
* Author: Dag Brattli <dagb@cs.uit.no>
* Created at: Tue Dec 9 21:18:38 1997
* Modified at: Sun Oct 27 22:13:30 2002
* Modified by: Martin Diehl <mad@mdiehl.de>
* Sources: slip.c by Laurence Culhane, <loz@holmes.demon.co.uk>
* Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
*
* Copyright (c) 1998-2000 Dag Brattli,
* Copyright (c) 2002 Martin Diehl,
* All Rights Reserved.
*
* 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; either version 2 of
* the License, or (at your option) any later version.
*
* Neither Dag Brattli nor University of Tromsø admit liability nor
* provide warranty for any of this software. This material is
* provided "AS-IS" and at no charge.
*
********************************************************************/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/tty.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <linux/smp_lock.h>
#include <linux/delay.h>
#include <net/irda/irda.h>
#include <net/irda/irda_device.h>
#include "sir-dev.h"
#include "irtty-sir.h"
static int qos_mtt_bits = 0x03; /* 5 ms or more */
module_param(qos_mtt_bits, int, 0);
MODULE_PARM_DESC(qos_mtt_bits, "Minimum Turn Time");
/* ------------------------------------------------------- */
/* device configuration callbacks always invoked with irda-thread context */
/* find out, how many chars we have in buffers below us
* this is allowed to lie, i.e. return less chars than we
* actually have. The returned value is used to determine
* how long the irdathread should wait before doing the
* real blocking wait_until_sent()
*/
static int irtty_chars_in_buffer(struct sir_dev *dev)
{
struct sirtty_cb *priv = dev->priv;
IRDA_ASSERT(priv != NULL, return -1;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
return priv->tty->driver->chars_in_buffer(priv->tty);
}
/* Wait (sleep) until underlaying hardware finished transmission
* i.e. hardware buffers are drained
* this must block and not return before all characters are really sent
*
* If the tty sits on top of a 16550A-like uart, there are typically
* up to 16 bytes in the fifo - f.e. 9600 bps 8N1 needs 16.7 msec
*
* With usbserial the uart-fifo is basically replaced by the converter's
* outgoing endpoint buffer, which can usually hold 64 bytes (at least).
* With pl2303 it appears we are safe with 60msec here.
*
* I really wish all serial drivers would provide
* correct implementation of wait_until_sent()
*/
#define USBSERIAL_TX_DONE_DELAY 60
static void irtty_wait_until_sent(struct sir_dev *dev)
{
struct sirtty_cb *priv = dev->priv;
struct tty_struct *tty;
IRDA_ASSERT(priv != NULL, return;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
tty = priv->tty;
if (tty->driver->wait_until_sent) {
lock_kernel();
tty->driver->wait_until_sent(tty, msecs_to_jiffies(100));
unlock_kernel();
}
else {
msleep(USBSERIAL_TX_DONE_DELAY);
}
}
/*
* Function irtty_change_speed (dev, speed)
*
* Change the speed of the serial port.
*
* This may sleep in set_termios (usbserial driver f.e.) and must
* not be called from interrupt/timer/tasklet therefore.
* All such invocations are deferred to kIrDAd now so we can sleep there.
*/
static int irtty_change_speed(struct sir_dev *dev, unsigned speed)
{
struct sirtty_cb *priv = dev->priv;
struct tty_struct *tty;
struct termios old_termios;
int cflag;
IRDA_ASSERT(priv != NULL, return -1;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
tty = priv->tty;
lock_kernel();
old_termios = *(tty->termios);
cflag = tty->termios->c_cflag;
cflag &= ~CBAUD;
IRDA_DEBUG(2, "%s(), Setting speed to %d\n", __FUNCTION__, speed);
switch (speed) {
case 1200:
cflag |= B1200;
break;
case 2400:
cflag |= B2400;
break;
case 4800:
cflag |= B4800;
break;
case 19200:
cflag |= B19200;
break;
case 38400:
cflag |= B38400;
break;
case 57600:
cflag |= B57600;
break;
case 115200:
cflag |= B115200;
break;
case 9600:
default:
cflag |= B9600;
break;
}
tty->termios->c_cflag = cflag;
if (tty->driver->set_termios)
tty->driver->set_termios(tty, &old_termios);
unlock_kernel();
priv->io.speed = speed;
return 0;
}
/*
* Function irtty_set_dtr_rts (dev, dtr, rts)
*
* This function can be used by dongles etc. to set or reset the status
* of the dtr and rts lines
*/
static int irtty_set_dtr_rts(struct sir_dev *dev, int dtr, int rts)
{
struct sirtty_cb *priv = dev->priv;
int set = 0;
int clear = 0;
IRDA_ASSERT(priv != NULL, return -1;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
if (rts)
set |= TIOCM_RTS;
else
clear |= TIOCM_RTS;
if (dtr)
set |= TIOCM_DTR;
else
clear |= TIOCM_DTR;
/*
* We can't use ioctl() because it expects a non-null file structure,
* and we don't have that here.
* This function is not yet defined for all tty driver, so
* let's be careful... Jean II
*/
IRDA_ASSERT(priv->tty->driver->tiocmset != NULL, return -1;);
priv->tty->driver->tiocmset(priv->tty, NULL, set, clear);
return 0;
}
/* ------------------------------------------------------- */
/* called from sir_dev when there is more data to send
* context is either netdev->hard_xmit or some transmit-completion bh
* i.e. we are under spinlock here and must not sleep.
*/
static int irtty_do_write(struct sir_dev *dev, const unsigned char *ptr, size_t len)
{
struct sirtty_cb *priv = dev->priv;
struct tty_struct *tty;
int writelen;
IRDA_ASSERT(priv != NULL, return -1;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -1;);
tty = priv->tty;
if (!tty->driver->write)
return 0;
tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
if (tty->driver->write_room) {
writelen = tty->driver->write_room(tty);
if (writelen > len)
writelen = len;
}
else
writelen = len;
return tty->driver->write(tty, ptr, writelen);
}
/* ------------------------------------------------------- */
/* irda line discipline callbacks */
/*
* Function irtty_receive_buf( tty, cp, count)
*
* Handle the 'receiver data ready' interrupt. This function is called
* by the 'tty_io' module in the kernel when a block of IrDA data has
* been received, which can now be decapsulated and delivered for
* further processing
*
* calling context depends on underlying driver and tty->low_latency!
* for example (low_latency: 1 / 0):
* serial.c: uart-interrupt / softint
* usbserial: urb-complete-interrupt / softint
*/
static void irtty_receive_buf(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count)
{
struct sir_dev *dev;
struct sirtty_cb *priv = tty->disc_data;
int i;
IRDA_ASSERT(priv != NULL, return;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
if (unlikely(count==0)) /* yes, this happens */
return;
dev = priv->dev;
if (!dev) {
IRDA_WARNING("%s(), not ready yet!\n", __FUNCTION__);
return;
}
for (i = 0; i < count; i++) {
/*
* Characters received with a parity error, etc?
*/
if (fp && *fp++) {
IRDA_DEBUG(0, "Framing or parity error!\n");
sirdev_receive(dev, NULL, 0); /* notify sir_dev (updating stats) */
return;
}
}
sirdev_receive(dev, cp, count);
}
/*
* Function irtty_write_wakeup (tty)
*
* Called by the driver when there's room for more data. If we have
* more packets to send, we send them here.
*
*/
static void irtty_write_wakeup(struct tty_struct *tty)
{
struct sirtty_cb *priv = tty->disc_data;
IRDA_ASSERT(priv != NULL, return;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
if (priv->dev)
sirdev_write_complete(priv->dev);
}
/* ------------------------------------------------------- */
/*
* Function irtty_stop_receiver (tty, stop)
*
*/
static inline void irtty_stop_receiver(struct tty_struct *tty, int stop)
{
struct termios old_termios;
int cflag;
lock_kernel();
old_termios = *(tty->termios);
cflag = tty->termios->c_cflag;
if (stop)
cflag &= ~CREAD;
else
cflag |= CREAD;
tty->termios->c_cflag = cflag;
if (tty->driver->set_termios)
tty->driver->set_termios(tty, &old_termios);
unlock_kernel();
}
/*****************************************************************/
/* serialize ldisc open/close with sir_dev */
static DECLARE_MUTEX(irtty_sem);
/* notifier from sir_dev when irda% device gets opened (ifup) */
static int irtty_start_dev(struct sir_dev *dev)
{
struct sirtty_cb *priv;
struct tty_struct *tty;
/* serialize with ldisc open/close */
down(&irtty_sem);
priv = dev->priv;
if (unlikely(!priv || priv->magic!=IRTTY_MAGIC)) {
up(&irtty_sem);
return -ESTALE;
}
tty = priv->tty;
if (tty->driver->start)
tty->driver->start(tty);
/* Make sure we can receive more data */
irtty_stop_receiver(tty, FALSE);
up(&irtty_sem);
return 0;
}
/* notifier from sir_dev when irda% device gets closed (ifdown) */
static int irtty_stop_dev(struct sir_dev *dev)
{
struct sirtty_cb *priv;
struct tty_struct *tty;
/* serialize with ldisc open/close */
down(&irtty_sem);
priv = dev->priv;
if (unlikely(!priv || priv->magic!=IRTTY_MAGIC)) {
up(&irtty_sem);
return -ESTALE;
}
tty = priv->tty;
/* Make sure we don't receive more data */
irtty_stop_receiver(tty, TRUE);
if (tty->driver->stop)
tty->driver->stop(tty);
up(&irtty_sem);
return 0;
}
/* ------------------------------------------------------- */
static struct sir_driver sir_tty_drv = {
.owner = THIS_MODULE,
.driver_name = "sir_tty",
.start_dev = irtty_start_dev,
.stop_dev = irtty_stop_dev,
.do_write = irtty_do_write,
.chars_in_buffer = irtty_chars_in_buffer,
.wait_until_sent = irtty_wait_until_sent,
.set_speed = irtty_change_speed,
.set_dtr_rts = irtty_set_dtr_rts,
};
/* ------------------------------------------------------- */
/*
* Function irtty_ioctl (tty, file, cmd, arg)
*
* The Swiss army knife of system calls :-)
*
*/
static int irtty_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
{
struct irtty_info { char name[6]; } info;
struct sir_dev *dev;
struct sirtty_cb *priv = tty->disc_data;
int err = 0;
IRDA_ASSERT(priv != NULL, return -ENODEV;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return -EBADR;);
IRDA_DEBUG(3, "%s(cmd=0x%X)\n", __FUNCTION__, cmd);
dev = priv->dev;
IRDA_ASSERT(dev != NULL, return -1;);
switch (cmd) {
case TCGETS:
case TCGETA:
err = n_tty_ioctl(tty, file, cmd, arg);
break;
case IRTTY_IOCTDONGLE:
/* this call blocks for completion */
err = sirdev_set_dongle(dev, (IRDA_DONGLE) arg);
break;
case IRTTY_IOCGET:
IRDA_ASSERT(dev->netdev != NULL, return -1;);
memset(&info, 0, sizeof(info));
strncpy(info.name, dev->netdev->name, sizeof(info.name)-1);
if (copy_to_user((void __user *)arg, &info, sizeof(info)))
err = -EFAULT;
break;
default:
err = -ENOIOCTLCMD;
break;
}
return err;
}
/*
* Function irtty_open(tty)
*
* This function is called by the TTY module when the IrDA line
* discipline is called for. Because we are sure the tty line exists,
* we only have to link it to a free IrDA channel.
*/
static int irtty_open(struct tty_struct *tty)
{
struct sir_dev *dev;
struct sirtty_cb *priv;
int ret = 0;
/* Module stuff handled via irda_ldisc.owner - Jean II */
/* First make sure we're not already connected. */
if (tty->disc_data != NULL) {
priv = tty->disc_data;
if (priv && priv->magic == IRTTY_MAGIC) {
ret = -EEXIST;
goto out;
}
tty->disc_data = NULL; /* ### */
}
/* stop the underlying driver */
irtty_stop_receiver(tty, TRUE);
if (tty->driver->stop)
tty->driver->stop(tty);
if (tty->driver->flush_buffer)
tty->driver->flush_buffer(tty);
/* apply mtt override */
sir_tty_drv.qos_mtt_bits = qos_mtt_bits;
/* get a sir device instance for this driver */
dev = sirdev_get_instance(&sir_tty_drv, tty->name);
if (!dev) {
ret = -ENODEV;
goto out;
}
/* allocate private device info block */
priv = kmalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
goto out_put;
memset(priv, 0, sizeof(*priv));
priv->magic = IRTTY_MAGIC;
priv->tty = tty;
priv->dev = dev;
/* serialize with start_dev - in case we were racing with ifup */
down(&irtty_sem);
dev->priv = priv;
tty->disc_data = priv;
tty->receive_room = 65536;
up(&irtty_sem);
IRDA_DEBUG(0, "%s - %s: irda line discipline opened\n", __FUNCTION__, tty->name);
return 0;
out_put:
sirdev_put_instance(dev);
out:
return ret;
}
/*
* Function irtty_close (tty)
*
* Close down a IrDA channel. This means flushing out any pending queues,
* and then restoring the TTY line discipline to what it was before it got
* hooked to IrDA (which usually is TTY again).
*/
static void irtty_close(struct tty_struct *tty)
{
struct sirtty_cb *priv = tty->disc_data;
IRDA_ASSERT(priv != NULL, return;);
IRDA_ASSERT(priv->magic == IRTTY_MAGIC, return;);
/* Hm, with a dongle attached the dongle driver wants
* to close the dongle - which requires the use of
* some tty write and/or termios or ioctl operations.
* Are we allowed to call those when already requested
* to shutdown the ldisc?
* If not, we should somehow mark the dev being staled.
* Question remains, how to close the dongle in this case...
* For now let's assume we are granted to issue tty driver calls
* until we return here from the ldisc close. I'm just wondering
* how this behaves with hotpluggable serial hardware like
* rs232-pcmcia card or usb-serial...
*
* priv->tty = NULL?;
*/
/* we are dead now */
tty->disc_data = NULL;
sirdev_put_instance(priv->dev);
/* Stop tty */
irtty_stop_receiver(tty, TRUE);
tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
if (tty->driver->stop)
tty->driver->stop(tty);
kfree(priv);
IRDA_DEBUG(0, "%s - %s: irda line discipline closed\n", __FUNCTION__, tty->name);
}
/* ------------------------------------------------------- */
static struct tty_ldisc irda_ldisc = {
.magic = TTY_LDISC_MAGIC,
.name = "irda",
.flags = 0,
.open = irtty_open,
.close = irtty_close,
.read = NULL,
.write = NULL,
.ioctl = irtty_ioctl,
.poll = NULL,
.receive_buf = irtty_receive_buf,
.write_wakeup = irtty_write_wakeup,
.owner = THIS_MODULE,
};
/* ------------------------------------------------------- */
static int __init irtty_sir_init(void)
{
int err;
if ((err = tty_register_ldisc(N_IRDA, &irda_ldisc)) != 0)
IRDA_ERROR("IrDA: can't register line discipline (err = %d)\n",
err);
return err;
}
static void __exit irtty_sir_cleanup(void)
{
int err;
if ((err = tty_unregister_ldisc(N_IRDA))) {
IRDA_ERROR("%s(), can't unregister line discipline (err = %d)\n",
__FUNCTION__, err);
}
}
module_init(irtty_sir_init);
module_exit(irtty_sir_cleanup);
MODULE_AUTHOR("Dag Brattli <dagb@cs.uit.no>");
MODULE_DESCRIPTION("IrDA TTY device driver");
MODULE_ALIAS_LDISC(N_IRDA);
MODULE_LICENSE("GPL");
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