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linux/drivers/usb/serial/empeg.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

585 lines
15 KiB
C
Raw Blame History

/*
* USB Empeg empeg-car player driver
*
* Copyright (C) 2000, 2001
* Gary Brubaker (xavyer@ix.netcom.com)
*
* Copyright (C) 1999 - 2001
* Greg Kroah-Hartman (greg@kroah.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.
*
* See Documentation/usb/usb-serial.txt for more information on using this driver
*
* (07/16/2001) gb
* remove unused code in empeg_close() (thanks to Oliver Neukum for pointing this
* out) and rewrote empeg_set_termios().
*
* (05/30/2001) gkh
* switched from using spinlock to a semaphore, which fixes lots of problems.
*
* (04/08/2001) gb
* Identify version on module load.
*
* (01/22/2001) gb
* Added write_room() and chars_in_buffer() support.
*
* (12/21/2000) gb
* Moved termio stuff inside the port->active check.
* Moved MOD_DEC_USE_COUNT to end of empeg_close().
*
* (12/03/2000) gb
* Added port->tty->ldisc.set_termios(port->tty, NULL) to empeg_open()
* This notifies the tty driver that the termios have changed.
*
* (11/13/2000) gb
* Moved tty->low_latency = 1 from empeg_read_bulk_callback() to empeg_open()
* (It only needs to be set once - Doh!)
*
* (11/11/2000) gb
* Updated to work with id_table structure.
*
* (11/04/2000) gb
* Forked this from visor.c, and hacked it up to work with an
* Empeg ltd. empeg-car player. Constructive criticism welcomed.
* I would like to say, 'Thank You' to Greg Kroah-Hartman for the
* use of his code, and for his guidance, advice and patience. :)
* A 'Thank You' is in order for John Ripley of Empeg ltd for his
* advice, and patience too.
*
*/
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <asm/uaccess.h>
#include <linux/usb.h>
#include "usb-serial.h"
static int debug;
/*
* Version Information
*/
#define DRIVER_VERSION "v1.2"
#define DRIVER_AUTHOR "Greg Kroah-Hartman <greg@kroah.com>, Gary Brubaker <xavyer@ix.netcom.com>"
#define DRIVER_DESC "USB Empeg Mark I/II Driver"
#define EMPEG_VENDOR_ID 0x084f
#define EMPEG_PRODUCT_ID 0x0001
/* function prototypes for an empeg-car player */
static int empeg_open (struct usb_serial_port *port, struct file *filp);
static void empeg_close (struct usb_serial_port *port, struct file *filp);
static int empeg_write (struct usb_serial_port *port,
const unsigned char *buf,
int count);
static int empeg_write_room (struct usb_serial_port *port);
static int empeg_chars_in_buffer (struct usb_serial_port *port);
static void empeg_throttle (struct usb_serial_port *port);
static void empeg_unthrottle (struct usb_serial_port *port);
static int empeg_startup (struct usb_serial *serial);
static void empeg_shutdown (struct usb_serial *serial);
static int empeg_ioctl (struct usb_serial_port *port,
struct file * file,
unsigned int cmd,
unsigned long arg);
static void empeg_set_termios (struct usb_serial_port *port, struct termios *old_termios);
static void empeg_write_bulk_callback (struct urb *urb, struct pt_regs *regs);
static void empeg_read_bulk_callback (struct urb *urb, struct pt_regs *regs);
static struct usb_device_id id_table [] = {
{ USB_DEVICE(EMPEG_VENDOR_ID, EMPEG_PRODUCT_ID) },
{ } /* Terminating entry */
};
MODULE_DEVICE_TABLE (usb, id_table);
static struct usb_driver empeg_driver = {
.name = "empeg",
.probe = usb_serial_probe,
.disconnect = usb_serial_disconnect,
.id_table = id_table,
.no_dynamic_id = 1,
};
static struct usb_serial_driver empeg_device = {
.driver = {
.owner = THIS_MODULE,
.name = "empeg",
},
.id_table = id_table,
.num_interrupt_in = 0,
.num_bulk_in = 1,
.num_bulk_out = 1,
.num_ports = 1,
.open = empeg_open,
.close = empeg_close,
.throttle = empeg_throttle,
.unthrottle = empeg_unthrottle,
.attach = empeg_startup,
.shutdown = empeg_shutdown,
.ioctl = empeg_ioctl,
.set_termios = empeg_set_termios,
.write = empeg_write,
.write_room = empeg_write_room,
.chars_in_buffer = empeg_chars_in_buffer,
.write_bulk_callback = empeg_write_bulk_callback,
.read_bulk_callback = empeg_read_bulk_callback,
};
#define NUM_URBS 16
#define URB_TRANSFER_BUFFER_SIZE 4096
static struct urb *write_urb_pool[NUM_URBS];
static spinlock_t write_urb_pool_lock;
static int bytes_in;
static int bytes_out;
/******************************************************************************
* Empeg specific driver functions
******************************************************************************/
static int empeg_open (struct usb_serial_port *port, struct file *filp)
{
struct usb_serial *serial = port->serial;
int result = 0;
dbg("%s - port %d", __FUNCTION__, port->number);
/* Force default termio settings */
empeg_set_termios (port, NULL) ;
bytes_in = 0;
bytes_out = 0;
/* Start reading from the device */
usb_fill_bulk_urb(
port->read_urb,
serial->dev,
usb_rcvbulkpipe(serial->dev,
port->bulk_in_endpointAddress),
port->read_urb->transfer_buffer,
port->read_urb->transfer_buffer_length,
empeg_read_bulk_callback,
port);
result = usb_submit_urb(port->read_urb, GFP_KERNEL);
if (result)
dev_err(&port->dev, "%s - failed submitting read urb, error %d\n", __FUNCTION__, result);
return result;
}
static void empeg_close (struct usb_serial_port *port, struct file * filp)
{
dbg("%s - port %d", __FUNCTION__, port->number);
/* shutdown our bulk read */
usb_kill_urb(port->read_urb);
/* Uncomment the following line if you want to see some statistics in your syslog */
/* dev_info (&port->dev, "Bytes In = %d Bytes Out = %d\n", bytes_in, bytes_out); */
}
static int empeg_write (struct usb_serial_port *port, const unsigned char *buf, int count)
{
struct usb_serial *serial = port->serial;
struct urb *urb;
const unsigned char *current_position = buf;
unsigned long flags;
int status;
int i;
int bytes_sent = 0;
int transfer_size;
dbg("%s - port %d", __FUNCTION__, port->number);
while (count > 0) {
/* try to find a free urb in our list of them */
urb = NULL;
spin_lock_irqsave (&write_urb_pool_lock, flags);
for (i = 0; i < NUM_URBS; ++i) {
if (write_urb_pool[i]->status != -EINPROGRESS) {
urb = write_urb_pool[i];
break;
}
}
spin_unlock_irqrestore (&write_urb_pool_lock, flags);
if (urb == NULL) {
dbg("%s - no more free urbs", __FUNCTION__);
goto exit;
}
if (urb->transfer_buffer == NULL) {
urb->transfer_buffer = kmalloc (URB_TRANSFER_BUFFER_SIZE, GFP_ATOMIC);
if (urb->transfer_buffer == NULL) {
dev_err(&port->dev, "%s no more kernel memory...\n", __FUNCTION__);
goto exit;
}
}
transfer_size = min (count, URB_TRANSFER_BUFFER_SIZE);
memcpy (urb->transfer_buffer, current_position, transfer_size);
usb_serial_debug_data(debug, &port->dev, __FUNCTION__, transfer_size, urb->transfer_buffer);
/* build up our urb */
usb_fill_bulk_urb (
urb,
serial->dev,
usb_sndbulkpipe(serial->dev,
port->bulk_out_endpointAddress),
urb->transfer_buffer,
transfer_size,
empeg_write_bulk_callback,
port);
/* send it down the pipe */
status = usb_submit_urb(urb, GFP_ATOMIC);
if (status) {
dev_err(&port->dev, "%s - usb_submit_urb(write bulk) failed with status = %d\n", __FUNCTION__, status);
bytes_sent = status;
break;
}
current_position += transfer_size;
bytes_sent += transfer_size;
count -= transfer_size;
bytes_out += transfer_size;
}
exit:
return bytes_sent;
}
static int empeg_write_room (struct usb_serial_port *port)
{
unsigned long flags;
int i;
int room = 0;
dbg("%s - port %d", __FUNCTION__, port->number);
spin_lock_irqsave (&write_urb_pool_lock, flags);
/* tally up the number of bytes available */
for (i = 0; i < NUM_URBS; ++i) {
if (write_urb_pool[i]->status != -EINPROGRESS) {
room += URB_TRANSFER_BUFFER_SIZE;
}
}
spin_unlock_irqrestore (&write_urb_pool_lock, flags);
dbg("%s - returns %d", __FUNCTION__, room);
return (room);
}
static int empeg_chars_in_buffer (struct usb_serial_port *port)
{
unsigned long flags;
int i;
int chars = 0;
dbg("%s - port %d", __FUNCTION__, port->number);
spin_lock_irqsave (&write_urb_pool_lock, flags);
/* tally up the number of bytes waiting */
for (i = 0; i < NUM_URBS; ++i) {
if (write_urb_pool[i]->status == -EINPROGRESS) {
chars += URB_TRANSFER_BUFFER_SIZE;
}
}
spin_unlock_irqrestore (&write_urb_pool_lock, flags);
dbg("%s - returns %d", __FUNCTION__, chars);
return (chars);
}
static void empeg_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
{
struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
dbg("%s - port %d", __FUNCTION__, port->number);
if (urb->status) {
dbg("%s - nonzero write bulk status received: %d", __FUNCTION__, urb->status);
return;
}
schedule_work(&port->work);
}
static void empeg_read_bulk_callback (struct urb *urb, struct pt_regs *regs)
{
struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
struct tty_struct *tty;
unsigned char *data = urb->transfer_buffer;
int result;
dbg("%s - port %d", __FUNCTION__, port->number);
if (urb->status) {
dbg("%s - nonzero read bulk status received: %d", __FUNCTION__, urb->status);
return;
}
usb_serial_debug_data(debug, &port->dev, __FUNCTION__, urb->actual_length, data);
tty = port->tty;
if (urb->actual_length) {
tty_buffer_request_room(tty, urb->actual_length);
tty_insert_flip_string(tty, data, urb->actual_length);
tty_flip_buffer_push(tty);
bytes_in += urb->actual_length;
}
/* Continue trying to always read */
usb_fill_bulk_urb(
port->read_urb,
port->serial->dev,
usb_rcvbulkpipe(port->serial->dev,
port->bulk_in_endpointAddress),
port->read_urb->transfer_buffer,
port->read_urb->transfer_buffer_length,
empeg_read_bulk_callback,
port);
result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
if (result)
dev_err(&urb->dev->dev, "%s - failed resubmitting read urb, error %d\n", __FUNCTION__, result);
return;
}
static void empeg_throttle (struct usb_serial_port *port)
{
dbg("%s - port %d", __FUNCTION__, port->number);
usb_kill_urb(port->read_urb);
}
static void empeg_unthrottle (struct usb_serial_port *port)
{
int result;
dbg("%s - port %d", __FUNCTION__, port->number);
port->read_urb->dev = port->serial->dev;
result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
if (result)
dev_err(&port->dev, "%s - failed submitting read urb, error %d\n", __FUNCTION__, result);
return;
}
static int empeg_startup (struct usb_serial *serial)
{
int r;
dbg("%s", __FUNCTION__);
if (serial->dev->actconfig->desc.bConfigurationValue != 1) {
err("active config #%d != 1 ??",
serial->dev->actconfig->desc.bConfigurationValue);
return -ENODEV;
}
dbg("%s - reset config", __FUNCTION__);
r = usb_reset_configuration (serial->dev);
/* continue on with initialization */
return r;
}
static void empeg_shutdown (struct usb_serial *serial)
{
dbg ("%s", __FUNCTION__);
}
static int empeg_ioctl (struct usb_serial_port *port, struct file * file, unsigned int cmd, unsigned long arg)
{
dbg("%s - port %d, cmd 0x%.4x", __FUNCTION__, port->number, cmd);
return -ENOIOCTLCMD;
}
static void empeg_set_termios (struct usb_serial_port *port, struct termios *old_termios)
{
dbg("%s - port %d", __FUNCTION__, port->number);
if ((!port->tty) || (!port->tty->termios)) {
dbg("%s - no tty structures", __FUNCTION__);
return;
}
/*
* The empeg-car player wants these particular tty settings.
* You could, for example, change the baud rate, however the
* player only supports 115200 (currently), so there is really
* no point in support for changes to the tty settings.
* (at least for now)
*
* The default requirements for this device are:
*/
port->tty->termios->c_iflag
&= ~(IGNBRK /* disable ignore break */
| BRKINT /* disable break causes interrupt */
| PARMRK /* disable mark parity errors */
| ISTRIP /* disable clear high bit of input characters */
| INLCR /* disable translate NL to CR */
| IGNCR /* disable ignore CR */
| ICRNL /* disable translate CR to NL */
| IXON); /* disable enable XON/XOFF flow control */
port->tty->termios->c_oflag
&= ~OPOST; /* disable postprocess output characters */
port->tty->termios->c_lflag
&= ~(ECHO /* disable echo input characters */
| ECHONL /* disable echo new line */
| ICANON /* disable erase, kill, werase, and rprnt special characters */
| ISIG /* disable interrupt, quit, and suspend special characters */
| IEXTEN); /* disable non-POSIX special characters */
port->tty->termios->c_cflag
&= ~(CSIZE /* no size */
| PARENB /* disable parity bit */
| CBAUD); /* clear current baud rate */
port->tty->termios->c_cflag
|= (CS8 /* character size 8 bits */
| B115200); /* baud rate 115200 */
/*
* Force low_latency on; otherwise the pushes are scheduled;
* this is bad as it opens up the possibility of dropping bytes
* on the floor. We don't want to drop bytes on the floor. :)
*/
port->tty->low_latency = 1;
return;
}
static int __init empeg_init (void)
{
struct urb *urb;
int i, retval;
/* create our write urb pool and transfer buffers */
spin_lock_init (&write_urb_pool_lock);
for (i = 0; i < NUM_URBS; ++i) {
urb = usb_alloc_urb(0, GFP_KERNEL);
write_urb_pool[i] = urb;
if (urb == NULL) {
err("No more urbs???");
continue;
}
urb->transfer_buffer = kmalloc (URB_TRANSFER_BUFFER_SIZE, GFP_KERNEL);
if (!urb->transfer_buffer) {
err("%s - out of memory for urb buffers.",
__FUNCTION__);
continue;
}
}
retval = usb_serial_register(&empeg_device);
if (retval)
goto failed_usb_serial_register;
retval = usb_register(&empeg_driver);
if (retval)
goto failed_usb_register;
info(DRIVER_VERSION ":" DRIVER_DESC);
return 0;
failed_usb_register:
usb_serial_deregister(&empeg_device);
failed_usb_serial_register:
for (i = 0; i < NUM_URBS; ++i) {
if (write_urb_pool[i]) {
kfree(write_urb_pool[i]->transfer_buffer);
usb_free_urb(write_urb_pool[i]);
}
}
return retval;
}
static void __exit empeg_exit (void)
{
int i;
unsigned long flags;
usb_deregister(&empeg_driver);
usb_serial_deregister (&empeg_device);
spin_lock_irqsave (&write_urb_pool_lock, flags);
for (i = 0; i < NUM_URBS; ++i) {
if (write_urb_pool[i]) {
/* FIXME - uncomment the following usb_kill_urb call when
* the host controllers get fixed to set urb->dev = NULL after
* the urb is finished. Otherwise this call oopses. */
/* usb_kill_urb(write_urb_pool[i]); */
kfree(write_urb_pool[i]->transfer_buffer);
usb_free_urb (write_urb_pool[i]);
}
}
spin_unlock_irqrestore (&write_urb_pool_lock, flags);
}
module_init(empeg_init);
module_exit(empeg_exit);
MODULE_AUTHOR( DRIVER_AUTHOR );
MODULE_DESCRIPTION( DRIVER_DESC );
MODULE_LICENSE("GPL");
module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug enabled or not");
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