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alistair23-linux/drivers/s390/net/ctctty.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

1262 lines
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/*
* $Id: ctctty.c,v 1.29 2005/04/05 08:50:44 mschwide Exp $
*
* CTC / ESCON network driver, tty interface.
*
* Copyright (C) 2001 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Fritz Elfert (elfert@de.ibm.com, felfert@millenux.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; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_reg.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <linux/devfs_fs_kernel.h>
#include "ctctty.h"
#include "ctcdbug.h"
#define CTC_TTY_MAJOR 43
#define CTC_TTY_MAX_DEVICES 64
#define CTC_ASYNC_MAGIC 0x49344C01 /* for paranoia-checking */
#define CTC_ASYNC_INITIALIZED 0x80000000 /* port was initialized */
#define CTC_ASYNC_NORMAL_ACTIVE 0x20000000 /* Normal device active */
#define CTC_ASYNC_CLOSING 0x08000000 /* Serial port is closing */
#define CTC_ASYNC_CTS_FLOW 0x04000000 /* Do CTS flow control */
#define CTC_ASYNC_CHECK_CD 0x02000000 /* i.e., CLOCAL */
#define CTC_ASYNC_HUP_NOTIFY 0x0001 /* Notify tty on hangups/closes */
#define CTC_ASYNC_NETDEV_OPEN 0x0002 /* Underlying netdev is open */
#define CTC_ASYNC_TX_LINESTAT 0x0004 /* Must send line status */
#define CTC_ASYNC_SPLIT_TERMIOS 0x0008 /* Sep. termios for dialin/out */
#define CTC_TTY_XMIT_SIZE 1024 /* Default bufsize for write */
#define CTC_SERIAL_XMIT_MAX 4000 /* Maximum bufsize for write */
/* Private data (similar to async_struct in <linux/serial.h>) */
typedef struct {
int magic;
int flags; /* defined in tty.h */
int mcr; /* Modem control register */
int msr; /* Modem status register */
int lsr; /* Line status register */
int line;
int count; /* # of fd on device */
int blocked_open; /* # of blocked opens */
struct net_device *netdev;
struct sk_buff_head tx_queue; /* transmit queue */
struct sk_buff_head rx_queue; /* receive queue */
struct tty_struct *tty; /* Pointer to corresponding tty */
wait_queue_head_t open_wait;
wait_queue_head_t close_wait;
struct semaphore write_sem;
struct tasklet_struct tasklet;
struct timer_list stoptimer;
} ctc_tty_info;
/* Description of one CTC-tty */
typedef struct {
struct tty_driver *ctc_tty_device; /* tty-device */
ctc_tty_info info[CTC_TTY_MAX_DEVICES]; /* Private data */
} ctc_tty_driver;
static ctc_tty_driver *driver;
/* Leave this unchanged unless you know what you do! */
#define MODEM_PARANOIA_CHECK
#define MODEM_DO_RESTART
#define CTC_TTY_NAME "ctctty"
static __u32 ctc_tty_magic = CTC_ASYNC_MAGIC;
static int ctc_tty_shuttingdown = 0;
static spinlock_t ctc_tty_lock;
/* ctc_tty_try_read() is called from within ctc_tty_rcv_skb()
* to stuff incoming data directly into a tty's flip-buffer. If the
* flip buffer is full, the packet gets queued up.
*
* Return:
* 1 = Success
* 0 = Failure, data has to be buffered and later processed by
* ctc_tty_readmodem().
*/
static int
ctc_tty_try_read(ctc_tty_info * info, struct sk_buff *skb)
{
int len;
struct tty_struct *tty;
DBF_TEXT(trace, 5, __FUNCTION__);
if ((tty = info->tty)) {
if (info->mcr & UART_MCR_RTS) {
len = skb->len;
tty_insert_flip_string(tty, skb->data, len);
tty_flip_buffer_push(tty);
kfree_skb(skb);
return 1;
}
}
return 0;
}
/* ctc_tty_readmodem() is called periodically from within timer-interrupt.
* It tries getting received data from the receive queue an stuff it into
* the tty's flip-buffer.
*/
static int
ctc_tty_readmodem(ctc_tty_info *info)
{
int ret = 1;
struct tty_struct *tty;
DBF_TEXT(trace, 5, __FUNCTION__);
if ((tty = info->tty)) {
if (info->mcr & UART_MCR_RTS) {
struct sk_buff *skb;
if ((skb = skb_dequeue(&info->rx_queue))) {
int len = skb->len;
tty_insert_flip_string(tty, skb->data, len);
skb_pull(skb, len);
tty_flip_buffer_push(tty);
if (skb->len > 0)
skb_queue_head(&info->rx_queue, skb);
else {
kfree_skb(skb);
ret = !skb_queue_empty(&info->rx_queue);
}
}
}
}
return ret;
}
void
ctc_tty_setcarrier(struct net_device *netdev, int on)
{
int i;
DBF_TEXT(trace, 4, __FUNCTION__);
if ((!driver) || ctc_tty_shuttingdown)
return;
for (i = 0; i < CTC_TTY_MAX_DEVICES; i++)
if (driver->info[i].netdev == netdev) {
ctc_tty_info *info = &driver->info[i];
if (on)
info->msr |= UART_MSR_DCD;
else
info->msr &= ~UART_MSR_DCD;
if ((info->flags & CTC_ASYNC_CHECK_CD) && (!on))
tty_hangup(info->tty);
}
}
void
ctc_tty_netif_rx(struct sk_buff *skb)
{
int i;
ctc_tty_info *info = NULL;
DBF_TEXT(trace, 5, __FUNCTION__);
if (!skb)
return;
if ((!skb->dev) || (!driver) || ctc_tty_shuttingdown) {
dev_kfree_skb(skb);
return;
}
for (i = 0; i < CTC_TTY_MAX_DEVICES; i++)
if (driver->info[i].netdev == skb->dev) {
info = &driver->info[i];
break;
}
if (!info) {
dev_kfree_skb(skb);
return;
}
if (skb->len < 6) {
dev_kfree_skb(skb);
return;
}
if (memcmp(skb->data, &ctc_tty_magic, sizeof(__u32))) {
dev_kfree_skb(skb);
return;
}
skb_pull(skb, sizeof(__u32));
i = *((int *)skb->data);
skb_pull(skb, sizeof(info->mcr));
if (i & UART_MCR_RTS) {
info->msr |= UART_MSR_CTS;
if (info->flags & CTC_ASYNC_CTS_FLOW)
info->tty->hw_stopped = 0;
} else {
info->msr &= ~UART_MSR_CTS;
if (info->flags & CTC_ASYNC_CTS_FLOW)
info->tty->hw_stopped = 1;
}
if (i & UART_MCR_DTR)
info->msr |= UART_MSR_DSR;
else
info->msr &= ~UART_MSR_DSR;
if (skb->len <= 0) {
kfree_skb(skb);
return;
}
/* Try to deliver directly via tty-flip-buf if queue is empty */
if (skb_queue_empty(&info->rx_queue))
if (ctc_tty_try_read(info, skb))
return;
/* Direct deliver failed or queue wasn't empty.
* Queue up for later dequeueing via timer-irq.
*/
skb_queue_tail(&info->rx_queue, skb);
/* Schedule dequeuing */
tasklet_schedule(&info->tasklet);
}
static int
ctc_tty_tint(ctc_tty_info * info)
{
struct sk_buff *skb = skb_dequeue(&info->tx_queue);
int stopped = (info->tty->hw_stopped || info->tty->stopped);
int wake = 1;
int rc;
DBF_TEXT(trace, 4, __FUNCTION__);
if (!info->netdev) {
if (skb)
kfree_skb(skb);
return 0;
}
if (info->flags & CTC_ASYNC_TX_LINESTAT) {
int skb_res = info->netdev->hard_header_len +
sizeof(info->mcr) + sizeof(__u32);
/* If we must update line status,
* create an empty dummy skb and insert it.
*/
if (skb)
skb_queue_head(&info->tx_queue, skb);
skb = dev_alloc_skb(skb_res);
if (!skb) {
printk(KERN_WARNING
"ctc_tty: Out of memory in %s%d tint\n",
CTC_TTY_NAME, info->line);
return 1;
}
skb_reserve(skb, skb_res);
stopped = 0;
wake = 0;
}
if (!skb)
return 0;
if (stopped) {
skb_queue_head(&info->tx_queue, skb);
return 1;
}
#if 0
if (skb->len > 0)
printk(KERN_DEBUG "tint: %d %02x\n", skb->len, *(skb->data));
else
printk(KERN_DEBUG "tint: %d STAT\n", skb->len);
#endif
memcpy(skb_push(skb, sizeof(info->mcr)), &info->mcr, sizeof(info->mcr));
memcpy(skb_push(skb, sizeof(__u32)), &ctc_tty_magic, sizeof(__u32));
rc = info->netdev->hard_start_xmit(skb, info->netdev);
if (rc) {
skb_pull(skb, sizeof(info->mcr) + sizeof(__u32));
if (skb->len > 0)
skb_queue_head(&info->tx_queue, skb);
else
kfree_skb(skb);
} else {
struct tty_struct *tty = info->tty;
info->flags &= ~CTC_ASYNC_TX_LINESTAT;
if (tty) {
tty_wakeup(tty);
}
}
return (skb_queue_empty(&info->tx_queue) ? 0 : 1);
}
/************************************************************
*
* Modem-functions
*
* mostly "stolen" from original Linux-serial.c and friends.
*
************************************************************/
static inline int
ctc_tty_paranoia_check(ctc_tty_info * info, char *name, const char *routine)
{
#ifdef MODEM_PARANOIA_CHECK
if (!info) {
printk(KERN_WARNING "ctc_tty: null info_struct for %s in %s\n",
name, routine);
return 1;
}
if (info->magic != CTC_ASYNC_MAGIC) {
printk(KERN_WARNING "ctc_tty: bad magic for info struct %s in %s\n",
name, routine);
return 1;
}
#endif
return 0;
}
static void
ctc_tty_inject(ctc_tty_info *info, char c)
{
int skb_res;
struct sk_buff *skb;
DBF_TEXT(trace, 4, __FUNCTION__);
if (ctc_tty_shuttingdown)
return;
skb_res = info->netdev->hard_header_len + sizeof(info->mcr) +
sizeof(__u32) + 1;
skb = dev_alloc_skb(skb_res);
if (!skb) {
printk(KERN_WARNING
"ctc_tty: Out of memory in %s%d tx_inject\n",
CTC_TTY_NAME, info->line);
return;
}
skb_reserve(skb, skb_res);
*(skb_put(skb, 1)) = c;
skb_queue_head(&info->tx_queue, skb);
tasklet_schedule(&info->tasklet);
}
static void
ctc_tty_transmit_status(ctc_tty_info *info)
{
DBF_TEXT(trace, 5, __FUNCTION__);
if (ctc_tty_shuttingdown)
return;
info->flags |= CTC_ASYNC_TX_LINESTAT;
tasklet_schedule(&info->tasklet);
}
static void
ctc_tty_change_speed(ctc_tty_info * info)
{
unsigned int cflag;
unsigned int quot;
int i;
DBF_TEXT(trace, 3, __FUNCTION__);
if (!info->tty || !info->tty->termios)
return;
cflag = info->tty->termios->c_cflag;
quot = i = cflag & CBAUD;
if (i & CBAUDEX) {
i &= ~CBAUDEX;
if (i < 1 || i > 2)
info->tty->termios->c_cflag &= ~CBAUDEX;
else
i += 15;
}
if (quot) {
info->mcr |= UART_MCR_DTR;
info->mcr |= UART_MCR_RTS;
ctc_tty_transmit_status(info);
} else {
info->mcr &= ~UART_MCR_DTR;
info->mcr &= ~UART_MCR_RTS;
ctc_tty_transmit_status(info);
return;
}
/* CTS flow control flag and modem status interrupts */
if (cflag & CRTSCTS) {
info->flags |= CTC_ASYNC_CTS_FLOW;
} else
info->flags &= ~CTC_ASYNC_CTS_FLOW;
if (cflag & CLOCAL)
info->flags &= ~CTC_ASYNC_CHECK_CD;
else {
info->flags |= CTC_ASYNC_CHECK_CD;
}
}
static int
ctc_tty_startup(ctc_tty_info * info)
{
DBF_TEXT(trace, 3, __FUNCTION__);
if (info->flags & CTC_ASYNC_INITIALIZED)
return 0;
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "starting up %s%d ...\n", CTC_TTY_NAME, info->line);
#endif
/*
* Now, initialize the UART
*/
info->mcr = UART_MCR_DTR | UART_MCR_RTS | UART_MCR_OUT2;
if (info->tty)
clear_bit(TTY_IO_ERROR, &info->tty->flags);
/*
* and set the speed of the serial port
*/
ctc_tty_change_speed(info);
info->flags |= CTC_ASYNC_INITIALIZED;
if (!(info->flags & CTC_ASYNC_NETDEV_OPEN))
info->netdev->open(info->netdev);
info->flags |= CTC_ASYNC_NETDEV_OPEN;
return 0;
}
static void
ctc_tty_stopdev(unsigned long data)
{
ctc_tty_info *info = (ctc_tty_info *)data;
if ((!info) || (!info->netdev) ||
(info->flags & CTC_ASYNC_INITIALIZED))
return;
info->netdev->stop(info->netdev);
info->flags &= ~CTC_ASYNC_NETDEV_OPEN;
}
/*
* This routine will shutdown a serial port; interrupts are disabled, and
* DTR is dropped if the hangup on close termio flag is on.
*/
static void
ctc_tty_shutdown(ctc_tty_info * info)
{
DBF_TEXT(trace, 3, __FUNCTION__);
if (!(info->flags & CTC_ASYNC_INITIALIZED))
return;
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "Shutting down %s%d ....\n", CTC_TTY_NAME, info->line);
#endif
info->msr &= ~UART_MSR_RI;
if (!info->tty || (info->tty->termios->c_cflag & HUPCL))
info->mcr &= ~(UART_MCR_DTR | UART_MCR_RTS);
if (info->tty)
set_bit(TTY_IO_ERROR, &info->tty->flags);
mod_timer(&info->stoptimer, jiffies + (10 * HZ));
skb_queue_purge(&info->tx_queue);
skb_queue_purge(&info->rx_queue);
info->flags &= ~CTC_ASYNC_INITIALIZED;
}
/* ctc_tty_write() is the main send-routine. It is called from the upper
* levels within the kernel to perform sending data. Depending on the
* online-flag it either directs output to the at-command-interpreter or
* to the lower level. Additional tasks done here:
* - If online, check for escape-sequence (+++)
* - If sending audio-data, call ctc_tty_DLEdown() to parse DLE-codes.
* - If receiving audio-data, call ctc_tty_end_vrx() to abort if needed.
* - If dialing, abort dial.
*/
static int
ctc_tty_write(struct tty_struct *tty, const u_char * buf, int count)
{
int c;
int total = 0;
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
DBF_TEXT(trace, 5, __FUNCTION__);
if (ctc_tty_shuttingdown)
goto ex;
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_write"))
goto ex;
if (!tty)
goto ex;
if (!info->netdev) {
total = -ENODEV;
goto ex;
}
while (1) {
struct sk_buff *skb;
int skb_res;
c = (count < CTC_TTY_XMIT_SIZE) ? count : CTC_TTY_XMIT_SIZE;
if (c <= 0)
break;
skb_res = info->netdev->hard_header_len + sizeof(info->mcr) +
+ sizeof(__u32);
skb = dev_alloc_skb(skb_res + c);
if (!skb) {
printk(KERN_WARNING
"ctc_tty: Out of memory in %s%d write\n",
CTC_TTY_NAME, info->line);
break;
}
skb_reserve(skb, skb_res);
memcpy(skb_put(skb, c), buf, c);
skb_queue_tail(&info->tx_queue, skb);
buf += c;
total += c;
count -= c;
}
if (!skb_queue_empty(&info->tx_queue)) {
info->lsr &= ~UART_LSR_TEMT;
tasklet_schedule(&info->tasklet);
}
ex:
DBF_TEXT(trace, 6, __FUNCTION__);
return total;
}
static int
ctc_tty_write_room(struct tty_struct *tty)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_write_room"))
return 0;
return CTC_TTY_XMIT_SIZE;
}
static int
ctc_tty_chars_in_buffer(struct tty_struct *tty)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_chars_in_buffer"))
return 0;
return 0;
}
static void
ctc_tty_flush_buffer(struct tty_struct *tty)
{
ctc_tty_info *info;
unsigned long flags;
DBF_TEXT(trace, 4, __FUNCTION__);
if (!tty)
goto ex;
spin_lock_irqsave(&ctc_tty_lock, flags);
info = (ctc_tty_info *) tty->driver_data;
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_flush_buffer")) {
spin_unlock_irqrestore(&ctc_tty_lock, flags);
goto ex;
}
skb_queue_purge(&info->tx_queue);
info->lsr |= UART_LSR_TEMT;
spin_unlock_irqrestore(&ctc_tty_lock, flags);
wake_up_interruptible(&tty->write_wait);
tty_wakeup(tty);
ex:
DBF_TEXT_(trace, 2, "ex: %s ", __FUNCTION__);
return;
}
static void
ctc_tty_flush_chars(struct tty_struct *tty)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
DBF_TEXT(trace, 4, __FUNCTION__);
if (ctc_tty_shuttingdown)
return;
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_flush_chars"))
return;
if (tty->stopped || tty->hw_stopped || skb_queue_empty(&info->tx_queue))
return;
tasklet_schedule(&info->tasklet);
}
/*
* ------------------------------------------------------------
* ctc_tty_throttle()
*
* This routine is called by the upper-layer tty layer to signal that
* incoming characters should be throttled.
* ------------------------------------------------------------
*/
static void
ctc_tty_throttle(struct tty_struct *tty)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
DBF_TEXT(trace, 4, __FUNCTION__);
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_throttle"))
return;
info->mcr &= ~UART_MCR_RTS;
if (I_IXOFF(tty))
ctc_tty_inject(info, STOP_CHAR(tty));
ctc_tty_transmit_status(info);
}
static void
ctc_tty_unthrottle(struct tty_struct *tty)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
DBF_TEXT(trace, 4, __FUNCTION__);
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_unthrottle"))
return;
info->mcr |= UART_MCR_RTS;
if (I_IXOFF(tty))
ctc_tty_inject(info, START_CHAR(tty));
ctc_tty_transmit_status(info);
}
/*
* ------------------------------------------------------------
* ctc_tty_ioctl() and friends
* ------------------------------------------------------------
*/
/*
* ctc_tty_get_lsr_info - get line status register info
*
* Purpose: Let user call ioctl() to get info when the UART physically
* is emptied. On bus types like RS485, the transmitter must
* release the bus after transmitting. This must be done when
* the transmit shift register is empty, not be done when the
* transmit holding register is empty. This functionality
* allows RS485 driver to be written in user space.
*/
static int
ctc_tty_get_lsr_info(ctc_tty_info * info, uint __user *value)
{
u_char status;
uint result;
ulong flags;
DBF_TEXT(trace, 4, __FUNCTION__);
spin_lock_irqsave(&ctc_tty_lock, flags);
status = info->lsr;
spin_unlock_irqrestore(&ctc_tty_lock, flags);
result = ((status & UART_LSR_TEMT) ? TIOCSER_TEMT : 0);
put_user(result, value);
return 0;
}
static int ctc_tty_tiocmget(struct tty_struct *tty, struct file *file)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
u_char control,
status;
uint result;
ulong flags;
DBF_TEXT(trace, 4, __FUNCTION__);
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_ioctl"))
return -ENODEV;
if (tty->flags & (1 << TTY_IO_ERROR))
return -EIO;
control = info->mcr;
spin_lock_irqsave(&ctc_tty_lock, flags);
status = info->msr;
spin_unlock_irqrestore(&ctc_tty_lock, flags);
result = ((control & UART_MCR_RTS) ? TIOCM_RTS : 0)
| ((control & UART_MCR_DTR) ? TIOCM_DTR : 0)
| ((status & UART_MSR_DCD) ? TIOCM_CAR : 0)
| ((status & UART_MSR_RI) ? TIOCM_RNG : 0)
| ((status & UART_MSR_DSR) ? TIOCM_DSR : 0)
| ((status & UART_MSR_CTS) ? TIOCM_CTS : 0);
return result;
}
static int
ctc_tty_tiocmset(struct tty_struct *tty, struct file *file,
unsigned int set, unsigned int clear)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
DBF_TEXT(trace, 4, __FUNCTION__);
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_ioctl"))
return -ENODEV;
if (tty->flags & (1 << TTY_IO_ERROR))
return -EIO;
if (set & TIOCM_RTS)
info->mcr |= UART_MCR_RTS;
if (set & TIOCM_DTR)
info->mcr |= UART_MCR_DTR;
if (clear & TIOCM_RTS)
info->mcr &= ~UART_MCR_RTS;
if (clear & TIOCM_DTR)
info->mcr &= ~UART_MCR_DTR;
if ((set | clear) & (TIOCM_RTS|TIOCM_DTR))
ctc_tty_transmit_status(info);
return 0;
}
static int
ctc_tty_ioctl(struct tty_struct *tty, struct file *file,
uint cmd, ulong arg)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
int error;
int retval;
DBF_TEXT(trace, 4, __FUNCTION__);
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_ioctl"))
return -ENODEV;
if (tty->flags & (1 << TTY_IO_ERROR))
return -EIO;
switch (cmd) {
case TCSBRK: /* SVID version: non-zero arg --> no break */
#ifdef CTC_DEBUG_MODEM_IOCTL
printk(KERN_DEBUG "%s%d ioctl TCSBRK\n", CTC_TTY_NAME, info->line);
#endif
retval = tty_check_change(tty);
if (retval)
return retval;
tty_wait_until_sent(tty, 0);
return 0;
case TCSBRKP: /* support for POSIX tcsendbreak() */
#ifdef CTC_DEBUG_MODEM_IOCTL
printk(KERN_DEBUG "%s%d ioctl TCSBRKP\n", CTC_TTY_NAME, info->line);
#endif
retval = tty_check_change(tty);
if (retval)
return retval;
tty_wait_until_sent(tty, 0);
return 0;
case TIOCGSOFTCAR:
#ifdef CTC_DEBUG_MODEM_IOCTL
printk(KERN_DEBUG "%s%d ioctl TIOCGSOFTCAR\n", CTC_TTY_NAME,
info->line);
#endif
error = put_user(C_CLOCAL(tty) ? 1 : 0, (ulong __user *) arg);
return error;
case TIOCSSOFTCAR:
#ifdef CTC_DEBUG_MODEM_IOCTL
printk(KERN_DEBUG "%s%d ioctl TIOCSSOFTCAR\n", CTC_TTY_NAME,
info->line);
#endif
error = get_user(arg, (ulong __user *) arg);
if (error)
return error;
tty->termios->c_cflag =
((tty->termios->c_cflag & ~CLOCAL) |
(arg ? CLOCAL : 0));
return 0;
case TIOCSERGETLSR: /* Get line status register */
#ifdef CTC_DEBUG_MODEM_IOCTL
printk(KERN_DEBUG "%s%d ioctl TIOCSERGETLSR\n", CTC_TTY_NAME,
info->line);
#endif
if (access_ok(VERIFY_WRITE, (void __user *) arg, sizeof(uint)))
return ctc_tty_get_lsr_info(info, (uint __user *) arg);
else
return -EFAULT;
default:
#ifdef CTC_DEBUG_MODEM_IOCTL
printk(KERN_DEBUG "UNKNOWN ioctl 0x%08x on %s%d\n", cmd,
CTC_TTY_NAME, info->line);
#endif
return -ENOIOCTLCMD;
}
return 0;
}
static void
ctc_tty_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
unsigned int cflag = tty->termios->c_cflag;
DBF_TEXT(trace, 4, __FUNCTION__);
ctc_tty_change_speed(info);
/* Handle transition to B0 */
if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD)) {
info->mcr &= ~(UART_MCR_DTR|UART_MCR_RTS);
ctc_tty_transmit_status(info);
}
/* Handle transition from B0 to other */
if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
info->mcr |= UART_MCR_DTR;
if (!(tty->termios->c_cflag & CRTSCTS) ||
!test_bit(TTY_THROTTLED, &tty->flags)) {
info->mcr |= UART_MCR_RTS;
}
ctc_tty_transmit_status(info);
}
/* Handle turning off CRTSCTS */
if ((old_termios->c_cflag & CRTSCTS) &&
!(tty->termios->c_cflag & CRTSCTS))
tty->hw_stopped = 0;
}
/*
* ------------------------------------------------------------
* ctc_tty_open() and friends
* ------------------------------------------------------------
*/
static int
ctc_tty_block_til_ready(struct tty_struct *tty, struct file *filp, ctc_tty_info *info)
{
DECLARE_WAITQUEUE(wait, NULL);
int do_clocal = 0;
unsigned long flags;
int retval;
DBF_TEXT(trace, 4, __FUNCTION__);
/*
* If the device is in the middle of being closed, then block
* until it's done, and then try again.
*/
if (tty_hung_up_p(filp) ||
(info->flags & CTC_ASYNC_CLOSING)) {
if (info->flags & CTC_ASYNC_CLOSING)
wait_event(info->close_wait,
!(info->flags & CTC_ASYNC_CLOSING));
#ifdef MODEM_DO_RESTART
if (info->flags & CTC_ASYNC_HUP_NOTIFY)
return -EAGAIN;
else
return -ERESTARTSYS;
#else
return -EAGAIN;
#endif
}
/*
* If non-blocking mode is set, then make the check up front
* and then exit.
*/
if ((filp->f_flags & O_NONBLOCK) ||
(tty->flags & (1 << TTY_IO_ERROR))) {
info->flags |= CTC_ASYNC_NORMAL_ACTIVE;
return 0;
}
if (tty->termios->c_cflag & CLOCAL)
do_clocal = 1;
/*
* Block waiting for the carrier detect and the line to become
* free (i.e., not in use by the callout). While we are in
* this loop, info->count is dropped by one, so that
* ctc_tty_close() knows when to free things. We restore it upon
* exit, either normal or abnormal.
*/
retval = 0;
add_wait_queue(&info->open_wait, &wait);
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_block_til_ready before block: %s%d, count = %d\n",
CTC_TTY_NAME, info->line, info->count);
#endif
spin_lock_irqsave(&ctc_tty_lock, flags);
if (!(tty_hung_up_p(filp)))
info->count--;
spin_unlock_irqrestore(&ctc_tty_lock, flags);
info->blocked_open++;
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
if (tty_hung_up_p(filp) ||
!(info->flags & CTC_ASYNC_INITIALIZED)) {
#ifdef MODEM_DO_RESTART
if (info->flags & CTC_ASYNC_HUP_NOTIFY)
retval = -EAGAIN;
else
retval = -ERESTARTSYS;
#else
retval = -EAGAIN;
#endif
break;
}
if (!(info->flags & CTC_ASYNC_CLOSING) &&
(do_clocal || (info->msr & UART_MSR_DCD))) {
break;
}
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_block_til_ready blocking: %s%d, count = %d\n",
CTC_TTY_NAME, info->line, info->count);
#endif
schedule();
}
current->state = TASK_RUNNING;
remove_wait_queue(&info->open_wait, &wait);
if (!tty_hung_up_p(filp))
info->count++;
info->blocked_open--;
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_block_til_ready after blocking: %s%d, count = %d\n",
CTC_TTY_NAME, info->line, info->count);
#endif
if (retval)
return retval;
info->flags |= CTC_ASYNC_NORMAL_ACTIVE;
return 0;
}
/*
* This routine is called whenever a serial port is opened. It
* enables interrupts for a serial port, linking in its async structure into
* the IRQ chain. It also performs the serial-specific
* initialization for the tty structure.
*/
static int
ctc_tty_open(struct tty_struct *tty, struct file *filp)
{
ctc_tty_info *info;
unsigned long saveflags;
int retval,
line;
DBF_TEXT(trace, 3, __FUNCTION__);
line = tty->index;
if (line < 0 || line > CTC_TTY_MAX_DEVICES)
return -ENODEV;
info = &driver->info[line];
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_open"))
return -ENODEV;
if (!info->netdev)
return -ENODEV;
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_open %s, count = %d\n", tty->name,
info->count);
#endif
spin_lock_irqsave(&ctc_tty_lock, saveflags);
info->count++;
tty->driver_data = info;
info->tty = tty;
spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
/*
* Start up serial port
*/
retval = ctc_tty_startup(info);
if (retval) {
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_open return after startup\n");
#endif
return retval;
}
retval = ctc_tty_block_til_ready(tty, filp, info);
if (retval) {
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_open return after ctc_tty_block_til_ready \n");
#endif
return retval;
}
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_open %s successful...\n", tty->name);
#endif
return 0;
}
static void
ctc_tty_close(struct tty_struct *tty, struct file *filp)
{
ctc_tty_info *info = (ctc_tty_info *) tty->driver_data;
ulong flags;
ulong timeout;
DBF_TEXT(trace, 3, __FUNCTION__);
if (!info || ctc_tty_paranoia_check(info, tty->name, "ctc_tty_close"))
return;
spin_lock_irqsave(&ctc_tty_lock, flags);
if (tty_hung_up_p(filp)) {
spin_unlock_irqrestore(&ctc_tty_lock, flags);
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_close return after tty_hung_up_p\n");
#endif
return;
}
if ((tty->count == 1) && (info->count != 1)) {
/*
* Uh, oh. tty->count is 1, which means that the tty
* structure will be freed. Info->count should always
* be one in these conditions. If it's greater than
* one, we've got real problems, since it means the
* serial port won't be shutdown.
*/
printk(KERN_ERR "ctc_tty_close: bad port count; tty->count is 1, "
"info->count is %d\n", info->count);
info->count = 1;
}
if (--info->count < 0) {
printk(KERN_ERR "ctc_tty_close: bad port count for %s%d: %d\n",
CTC_TTY_NAME, info->line, info->count);
info->count = 0;
}
if (info->count) {
local_irq_restore(flags);
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_close after info->count != 0\n");
#endif
return;
}
info->flags |= CTC_ASYNC_CLOSING;
tty->closing = 1;
/*
* At this point we stop accepting input. To do this, we
* disable the receive line status interrupts, and tell the
* interrupt driver to stop checking the data ready bit in the
* line status register.
*/
if (info->flags & CTC_ASYNC_INITIALIZED) {
tty_wait_until_sent(tty, 30*HZ); /* 30 seconds timeout */
/*
* Before we drop DTR, make sure the UART transmitter
* has completely drained; this is especially
* important if there is a transmit FIFO!
*/
timeout = jiffies + HZ;
while (!(info->lsr & UART_LSR_TEMT)) {
spin_unlock_irqrestore(&ctc_tty_lock, flags);
msleep(500);
spin_lock_irqsave(&ctc_tty_lock, flags);
if (time_after(jiffies,timeout))
break;
}
}
ctc_tty_shutdown(info);
if (tty->driver->flush_buffer) {
skb_queue_purge(&info->tx_queue);
info->lsr |= UART_LSR_TEMT;
}
tty_ldisc_flush(tty);
info->tty = 0;
tty->closing = 0;
if (info->blocked_open) {
msleep_interruptible(500);
wake_up_interruptible(&info->open_wait);
}
info->flags &= ~(CTC_ASYNC_NORMAL_ACTIVE | CTC_ASYNC_CLOSING);
wake_up_interruptible(&info->close_wait);
spin_unlock_irqrestore(&ctc_tty_lock, flags);
#ifdef CTC_DEBUG_MODEM_OPEN
printk(KERN_DEBUG "ctc_tty_close normal exit\n");
#endif
}
/*
* ctc_tty_hangup() --- called by tty_hangup() when a hangup is signaled.
*/
static void
ctc_tty_hangup(struct tty_struct *tty)
{
ctc_tty_info *info = (ctc_tty_info *)tty->driver_data;
unsigned long saveflags;
DBF_TEXT(trace, 3, __FUNCTION__);
if (ctc_tty_paranoia_check(info, tty->name, "ctc_tty_hangup"))
return;
ctc_tty_shutdown(info);
info->count = 0;
info->flags &= ~CTC_ASYNC_NORMAL_ACTIVE;
spin_lock_irqsave(&ctc_tty_lock, saveflags);
info->tty = 0;
spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
wake_up_interruptible(&info->open_wait);
}
/*
* For all online tty's, try sending data to
* the lower levels.
*/
static void
ctc_tty_task(unsigned long arg)
{
ctc_tty_info *info = (void *)arg;
unsigned long saveflags;
int again;
DBF_TEXT(trace, 3, __FUNCTION__);
spin_lock_irqsave(&ctc_tty_lock, saveflags);
if ((!ctc_tty_shuttingdown) && info) {
again = ctc_tty_tint(info);
if (!again)
info->lsr |= UART_LSR_TEMT;
again |= ctc_tty_readmodem(info);
if (again) {
tasklet_schedule(&info->tasklet);
}
}
spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
}
static struct tty_operations ctc_ops = {
.open = ctc_tty_open,
.close = ctc_tty_close,
.write = ctc_tty_write,
.flush_chars = ctc_tty_flush_chars,
.write_room = ctc_tty_write_room,
.chars_in_buffer = ctc_tty_chars_in_buffer,
.flush_buffer = ctc_tty_flush_buffer,
.ioctl = ctc_tty_ioctl,
.throttle = ctc_tty_throttle,
.unthrottle = ctc_tty_unthrottle,
.set_termios = ctc_tty_set_termios,
.hangup = ctc_tty_hangup,
.tiocmget = ctc_tty_tiocmget,
.tiocmset = ctc_tty_tiocmset,
};
int
ctc_tty_init(void)
{
int i;
ctc_tty_info *info;
struct tty_driver *device;
DBF_TEXT(trace, 2, __FUNCTION__);
driver = kmalloc(sizeof(ctc_tty_driver), GFP_KERNEL);
if (driver == NULL) {
printk(KERN_WARNING "Out of memory in ctc_tty_modem_init\n");
return -ENOMEM;
}
memset(driver, 0, sizeof(ctc_tty_driver));
device = alloc_tty_driver(CTC_TTY_MAX_DEVICES);
if (!device) {
kfree(driver);
printk(KERN_WARNING "Out of memory in ctc_tty_modem_init\n");
return -ENOMEM;
}
device->devfs_name = "ctc/" CTC_TTY_NAME;
device->name = CTC_TTY_NAME;
device->major = CTC_TTY_MAJOR;
device->minor_start = 0;
device->type = TTY_DRIVER_TYPE_SERIAL;
device->subtype = SERIAL_TYPE_NORMAL;
device->init_termios = tty_std_termios;
device->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
device->flags = TTY_DRIVER_REAL_RAW;
device->driver_name = "ctc_tty",
tty_set_operations(device, &ctc_ops);
if (tty_register_driver(device)) {
printk(KERN_WARNING "ctc_tty: Couldn't register serial-device\n");
put_tty_driver(device);
kfree(driver);
return -1;
}
driver->ctc_tty_device = device;
for (i = 0; i < CTC_TTY_MAX_DEVICES; i++) {
info = &driver->info[i];
init_MUTEX(&info->write_sem);
tasklet_init(&info->tasklet, ctc_tty_task,
(unsigned long) info);
info->magic = CTC_ASYNC_MAGIC;
info->line = i;
info->tty = 0;
info->count = 0;
info->blocked_open = 0;
init_waitqueue_head(&info->open_wait);
init_waitqueue_head(&info->close_wait);
skb_queue_head_init(&info->tx_queue);
skb_queue_head_init(&info->rx_queue);
init_timer(&info->stoptimer);
info->stoptimer.function = ctc_tty_stopdev;
info->stoptimer.data = (unsigned long)info;
info->mcr = UART_MCR_RTS;
}
return 0;
}
int
ctc_tty_register_netdev(struct net_device *dev) {
int ttynum;
char *err;
char *p;
DBF_TEXT(trace, 2, __FUNCTION__);
if ((!dev) || (!dev->name)) {
printk(KERN_WARNING
"ctc_tty_register_netdev called "
"with NULL dev or NULL dev-name\n");
return -1;
}
/*
* If the name is a format string the caller wants us to
* do a name allocation : format string must end with %d
*/
if (strchr(dev->name, '%'))
{
int err = dev_alloc_name(dev, dev->name); // dev->name is changed by this
if (err < 0) {
printk(KERN_DEBUG "dev_alloc returned error %d\n", err);
return err;
}
}
for (p = dev->name; p && ((*p < '0') || (*p > '9')); p++);
ttynum = simple_strtoul(p, &err, 0);
if ((ttynum < 0) || (ttynum >= CTC_TTY_MAX_DEVICES) ||
(err && *err)) {
printk(KERN_WARNING
"ctc_tty_register_netdev called "
"with number in name '%s'\n", dev->name);
return -1;
}
if (driver->info[ttynum].netdev) {
printk(KERN_WARNING
"ctc_tty_register_netdev called "
"for already registered device '%s'\n",
dev->name);
return -1;
}
driver->info[ttynum].netdev = dev;
return 0;
}
void
ctc_tty_unregister_netdev(struct net_device *dev) {
int i;
unsigned long saveflags;
ctc_tty_info *info = NULL;
DBF_TEXT(trace, 2, __FUNCTION__);
spin_lock_irqsave(&ctc_tty_lock, saveflags);
for (i = 0; i < CTC_TTY_MAX_DEVICES; i++)
if (driver->info[i].netdev == dev) {
info = &driver->info[i];
break;
}
if (info) {
info->netdev = NULL;
skb_queue_purge(&info->tx_queue);
skb_queue_purge(&info->rx_queue);
}
spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
}
void
ctc_tty_cleanup(void) {
unsigned long saveflags;
DBF_TEXT(trace, 2, __FUNCTION__);
spin_lock_irqsave(&ctc_tty_lock, saveflags);
ctc_tty_shuttingdown = 1;
spin_unlock_irqrestore(&ctc_tty_lock, saveflags);
tty_unregister_driver(driver->ctc_tty_device);
put_tty_driver(driver->ctc_tty_device);
kfree(driver);
driver = NULL;
}
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