linux/drivers/s390/char/sclp_tty.c

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/*
* drivers/s390/char/sclp_tty.c
* SCLP line mode terminal driver.
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Martin Peschke <mpeschke@de.ibm.com>
* Martin Schwidefsky <schwidefsky@de.ibm.com>
*/
#include <linux/module.h>
#include <linux/kmod.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
[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 04:54:13 +00:00
#include <linux/tty_flip.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#include <linux/gfp.h>
#include <asm/uaccess.h>
#include "ctrlchar.h"
#include "sclp.h"
#include "sclp_rw.h"
#include "sclp_tty.h"
/*
* size of a buffer that collects single characters coming in
* via sclp_tty_put_char()
*/
#define SCLP_TTY_BUF_SIZE 512
/*
* There is exactly one SCLP terminal, so we can keep things simple
* and allocate all variables statically.
*/
/* Lock to guard over changes to global variables. */
static spinlock_t sclp_tty_lock;
/* List of free pages that can be used for console output buffering. */
static struct list_head sclp_tty_pages;
/* List of full struct sclp_buffer structures ready for output. */
static struct list_head sclp_tty_outqueue;
/* Counter how many buffers are emitted. */
static int sclp_tty_buffer_count;
/* Pointer to current console buffer. */
static struct sclp_buffer *sclp_ttybuf;
/* Timer for delayed output of console messages. */
static struct timer_list sclp_tty_timer;
static struct tty_struct *sclp_tty;
static unsigned char sclp_tty_chars[SCLP_TTY_BUF_SIZE];
static unsigned short int sclp_tty_chars_count;
struct tty_driver *sclp_tty_driver;
static int sclp_tty_tolower;
static int sclp_tty_columns = 80;
#define SPACES_PER_TAB 8
#define CASE_DELIMITER 0x6c /* to separate upper and lower case (% in EBCDIC) */
/* This routine is called whenever we try to open a SCLP terminal. */
static int
sclp_tty_open(struct tty_struct *tty, struct file *filp)
{
sclp_tty = tty;
tty->driver_data = NULL;
tty->low_latency = 0;
return 0;
}
/* This routine is called when the SCLP terminal is closed. */
static void
sclp_tty_close(struct tty_struct *tty, struct file *filp)
{
if (tty->count > 1)
return;
sclp_tty = NULL;
}
/*
* This routine returns the numbers of characters the tty driver
* will accept for queuing to be written. This number is subject
* to change as output buffers get emptied, or if the output flow
* control is acted. This is not an exact number because not every
* character needs the same space in the sccb. The worst case is
* a string of newlines. Every newlines creates a new mto which
* needs 8 bytes.
*/
static int
sclp_tty_write_room (struct tty_struct *tty)
{
unsigned long flags;
struct list_head *l;
int count;
spin_lock_irqsave(&sclp_tty_lock, flags);
count = 0;
if (sclp_ttybuf != NULL)
count = sclp_buffer_space(sclp_ttybuf) / sizeof(struct mto);
list_for_each(l, &sclp_tty_pages)
count += NR_EMPTY_MTO_PER_SCCB;
spin_unlock_irqrestore(&sclp_tty_lock, flags);
return count;
}
static void
sclp_ttybuf_callback(struct sclp_buffer *buffer, int rc)
{
unsigned long flags;
void *page;
do {
page = sclp_unmake_buffer(buffer);
spin_lock_irqsave(&sclp_tty_lock, flags);
/* Remove buffer from outqueue */
list_del(&buffer->list);
sclp_tty_buffer_count--;
list_add_tail((struct list_head *) page, &sclp_tty_pages);
/* Check if there is a pending buffer on the out queue. */
buffer = NULL;
if (!list_empty(&sclp_tty_outqueue))
buffer = list_entry(sclp_tty_outqueue.next,
struct sclp_buffer, list);
spin_unlock_irqrestore(&sclp_tty_lock, flags);
} while (buffer && sclp_emit_buffer(buffer, sclp_ttybuf_callback));
/* check if the tty needs a wake up call */
if (sclp_tty != NULL) {
tty_wakeup(sclp_tty);
}
}
static inline void
__sclp_ttybuf_emit(struct sclp_buffer *buffer)
{
unsigned long flags;
int count;
int rc;
spin_lock_irqsave(&sclp_tty_lock, flags);
list_add_tail(&buffer->list, &sclp_tty_outqueue);
count = sclp_tty_buffer_count++;
spin_unlock_irqrestore(&sclp_tty_lock, flags);
if (count)
return;
rc = sclp_emit_buffer(buffer, sclp_ttybuf_callback);
if (rc)
sclp_ttybuf_callback(buffer, rc);
}
/*
* When this routine is called from the timer then we flush the
* temporary write buffer.
*/
static void
sclp_tty_timeout(unsigned long data)
{
unsigned long flags;
struct sclp_buffer *buf;
spin_lock_irqsave(&sclp_tty_lock, flags);
buf = sclp_ttybuf;
sclp_ttybuf = NULL;
spin_unlock_irqrestore(&sclp_tty_lock, flags);
if (buf != NULL) {
__sclp_ttybuf_emit(buf);
}
}
/*
* Write a string to the sclp tty.
*/
static int sclp_tty_write_string(const unsigned char *str, int count, int may_fail)
{
unsigned long flags;
void *page;
int written;
int overall_written;
struct sclp_buffer *buf;
if (count <= 0)
return 0;
overall_written = 0;
spin_lock_irqsave(&sclp_tty_lock, flags);
do {
/* Create a sclp output buffer if none exists yet */
if (sclp_ttybuf == NULL) {
while (list_empty(&sclp_tty_pages)) {
spin_unlock_irqrestore(&sclp_tty_lock, flags);
if (may_fail)
goto out;
else
sclp_sync_wait();
spin_lock_irqsave(&sclp_tty_lock, flags);
}
page = sclp_tty_pages.next;
list_del((struct list_head *) page);
sclp_ttybuf = sclp_make_buffer(page, sclp_tty_columns,
SPACES_PER_TAB);
}
/* try to write the string to the current output buffer */
written = sclp_write(sclp_ttybuf, str, count);
overall_written += written;
if (written == count)
break;
/*
* Not all characters could be written to the current
* output buffer. Emit the buffer, create a new buffer
* and then output the rest of the string.
*/
buf = sclp_ttybuf;
sclp_ttybuf = NULL;
spin_unlock_irqrestore(&sclp_tty_lock, flags);
__sclp_ttybuf_emit(buf);
spin_lock_irqsave(&sclp_tty_lock, flags);
str += written;
count -= written;
} while (count > 0);
/* Setup timer to output current console buffer after 1/10 second */
if (sclp_ttybuf && sclp_chars_in_buffer(sclp_ttybuf) &&
!timer_pending(&sclp_tty_timer)) {
init_timer(&sclp_tty_timer);
sclp_tty_timer.function = sclp_tty_timeout;
sclp_tty_timer.data = 0UL;
sclp_tty_timer.expires = jiffies + HZ/10;
add_timer(&sclp_tty_timer);
}
spin_unlock_irqrestore(&sclp_tty_lock, flags);
out:
return overall_written;
}
/*
* This routine is called by the kernel to write a series of characters to the
* tty device. The characters may come from user space or kernel space. This
* routine will return the number of characters actually accepted for writing.
*/
static int
sclp_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
if (sclp_tty_chars_count > 0) {
sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
sclp_tty_chars_count = 0;
}
return sclp_tty_write_string(buf, count, 1);
}
/*
* This routine is called by the kernel to write a single character to the tty
* device. If the kernel uses this routine, it must call the flush_chars()
* routine (if defined) when it is done stuffing characters into the driver.
*
* Characters provided to sclp_tty_put_char() are buffered by the SCLP driver.
* If the given character is a '\n' the contents of the SCLP write buffer
* - including previous characters from sclp_tty_put_char() and strings from
* sclp_write() without final '\n' - will be written.
*/
static int
sclp_tty_put_char(struct tty_struct *tty, unsigned char ch)
{
sclp_tty_chars[sclp_tty_chars_count++] = ch;
if (ch == '\n' || sclp_tty_chars_count >= SCLP_TTY_BUF_SIZE) {
sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
sclp_tty_chars_count = 0;
}
return 1;
}
/*
* This routine is called by the kernel after it has written a series of
* characters to the tty device using put_char().
*/
static void
sclp_tty_flush_chars(struct tty_struct *tty)
{
if (sclp_tty_chars_count > 0) {
sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
sclp_tty_chars_count = 0;
}
}
/*
* This routine returns the number of characters in the write buffer of the
* SCLP driver. The provided number includes all characters that are stored
* in the SCCB (will be written next time the SCLP is not busy) as well as
* characters in the write buffer (will not be written as long as there is a
* final line feed missing).
*/
static int
sclp_tty_chars_in_buffer(struct tty_struct *tty)
{
unsigned long flags;
struct list_head *l;
struct sclp_buffer *t;
int count;
spin_lock_irqsave(&sclp_tty_lock, flags);
count = 0;
if (sclp_ttybuf != NULL)
count = sclp_chars_in_buffer(sclp_ttybuf);
list_for_each(l, &sclp_tty_outqueue) {
t = list_entry(l, struct sclp_buffer, list);
count += sclp_chars_in_buffer(t);
}
spin_unlock_irqrestore(&sclp_tty_lock, flags);
return count;
}
/*
* removes all content from buffers of low level driver
*/
static void
sclp_tty_flush_buffer(struct tty_struct *tty)
{
if (sclp_tty_chars_count > 0) {
sclp_tty_write_string(sclp_tty_chars, sclp_tty_chars_count, 0);
sclp_tty_chars_count = 0;
}
}
/*
* push input to tty
*/
static void
sclp_tty_input(unsigned char* buf, unsigned int count)
{
unsigned int cchar;
/*
* If this tty driver is currently closed
* then throw the received input away.
*/
if (sclp_tty == NULL)
return;
cchar = ctrlchar_handle(buf, count, sclp_tty);
switch (cchar & CTRLCHAR_MASK) {
case CTRLCHAR_SYSRQ:
break;
case CTRLCHAR_CTRL:
[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 04:54:13 +00:00
tty_insert_flip_char(sclp_tty, cchar, TTY_NORMAL);
tty_flip_buffer_push(sclp_tty);
break;
case CTRLCHAR_NONE:
/* send (normal) input to line discipline */
if (count < 2 ||
[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 04:54:13 +00:00
(strncmp((const char *) buf + count - 2, "^n", 2) &&
strncmp((const char *) buf + count - 2, "\252n", 2))) {
/* add the auto \n */
tty_insert_flip_string(sclp_tty, buf, count);
tty_insert_flip_char(sclp_tty, '\n', TTY_NORMAL);
} else
[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 04:54:13 +00:00
tty_insert_flip_string(sclp_tty, buf, count - 2);
tty_flip_buffer_push(sclp_tty);
break;
}
}
/*
* get a EBCDIC string in upper/lower case,
* find out characters in lower/upper case separated by a special character,
* modifiy original string,
* returns length of resulting string
*/
static int sclp_switch_cases(unsigned char *buf, int count)
{
unsigned char *ip, *op;
int toggle;
/* initially changing case is off */
toggle = 0;
ip = op = buf;
while (count-- > 0) {
/* compare with special character */
if (*ip == CASE_DELIMITER) {
/* followed by another special character? */
if (count && ip[1] == CASE_DELIMITER) {
/*
* ... then put a single copy of the special
* character to the output string
*/
*op++ = *ip++;
count--;
} else
/*
* ... special character follower by a normal
* character toggles the case change behaviour
*/
toggle = ~toggle;
/* skip special character */
ip++;
} else
/* not the special character */
if (toggle)
/* but case switching is on */
if (sclp_tty_tolower)
/* switch to uppercase */
*op++ = _ebc_toupper[(int) *ip++];
else
/* switch to lowercase */
*op++ = _ebc_tolower[(int) *ip++];
else
/* no case switching, copy the character */
*op++ = *ip++;
}
/* return length of reformatted string. */
return op - buf;
}
static void sclp_get_input(struct gds_subvector *sv)
{
unsigned char *str;
int count;
str = (unsigned char *) (sv + 1);
count = sv->length - sizeof(*sv);
if (sclp_tty_tolower)
EBC_TOLOWER(str, count);
count = sclp_switch_cases(str, count);
/* convert EBCDIC to ASCII (modify original input in SCCB) */
sclp_ebcasc_str(str, count);
/* transfer input to high level driver */
sclp_tty_input(str, count);
}
static inline void sclp_eval_selfdeftextmsg(struct gds_subvector *sv)
{
void *end;
end = (void *) sv + sv->length;
for (sv = sv + 1; (void *) sv < end; sv = (void *) sv + sv->length)
if (sv->key == 0x30)
sclp_get_input(sv);
}
static inline void sclp_eval_textcmd(struct gds_vector *v)
{
struct gds_subvector *sv;
void *end;
end = (void *) v + v->length;
for (sv = (struct gds_subvector *) (v + 1);
(void *) sv < end; sv = (void *) sv + sv->length)
if (sv->key == GDS_KEY_SELFDEFTEXTMSG)
sclp_eval_selfdeftextmsg(sv);
}
static inline void sclp_eval_cpmsu(struct gds_vector *v)
{
void *end;
end = (void *) v + v->length;
for (v = v + 1; (void *) v < end; v = (void *) v + v->length)
if (v->gds_id == GDS_ID_TEXTCMD)
sclp_eval_textcmd(v);
}
static inline void sclp_eval_mdsmu(struct gds_vector *v)
{
v = sclp_find_gds_vector(v + 1, (void *) v + v->length, GDS_ID_CPMSU);
if (v)
sclp_eval_cpmsu(v);
}
static void sclp_tty_receiver(struct evbuf_header *evbuf)
{
struct gds_vector *v;
v = sclp_find_gds_vector(evbuf + 1, (void *) evbuf + evbuf->length,
GDS_ID_MDSMU);
if (v)
sclp_eval_mdsmu(v);
}
static void
sclp_tty_state_change(struct sclp_register *reg)
{
}
static struct sclp_register sclp_input_event =
{
.receive_mask = EVTYP_OPCMD_MASK | EVTYP_PMSGCMD_MASK,
.state_change_fn = sclp_tty_state_change,
.receiver_fn = sclp_tty_receiver
};
static const struct tty_operations sclp_ops = {
.open = sclp_tty_open,
.close = sclp_tty_close,
.write = sclp_tty_write,
.put_char = sclp_tty_put_char,
.flush_chars = sclp_tty_flush_chars,
.write_room = sclp_tty_write_room,
.chars_in_buffer = sclp_tty_chars_in_buffer,
.flush_buffer = sclp_tty_flush_buffer,
};
static int __init
sclp_tty_init(void)
{
struct tty_driver *driver;
void *page;
int i;
int rc;
if (!CONSOLE_IS_SCLP)
return 0;
driver = alloc_tty_driver(1);
if (!driver)
return -ENOMEM;
rc = sclp_rw_init();
if (rc) {
put_tty_driver(driver);
return rc;
}
/* Allocate pages for output buffering */
INIT_LIST_HEAD(&sclp_tty_pages);
for (i = 0; i < MAX_KMEM_PAGES; i++) {
page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
if (page == NULL) {
put_tty_driver(driver);
return -ENOMEM;
}
list_add_tail((struct list_head *) page, &sclp_tty_pages);
}
INIT_LIST_HEAD(&sclp_tty_outqueue);
spin_lock_init(&sclp_tty_lock);
init_timer(&sclp_tty_timer);
sclp_ttybuf = NULL;
sclp_tty_buffer_count = 0;
if (MACHINE_IS_VM) {
/*
* save 4 characters for the CPU number
* written at start of each line by VM/CP
*/
sclp_tty_columns = 76;
/* case input lines to lowercase */
sclp_tty_tolower = 1;
}
sclp_tty_chars_count = 0;
sclp_tty = NULL;
rc = sclp_register(&sclp_input_event);
if (rc) {
put_tty_driver(driver);
return rc;
}
driver->owner = THIS_MODULE;
driver->driver_name = "sclp_line";
driver->name = "sclp_line";
driver->major = TTY_MAJOR;
driver->minor_start = 64;
driver->type = TTY_DRIVER_TYPE_SYSTEM;
driver->subtype = SYSTEM_TYPE_TTY;
driver->init_termios = tty_std_termios;
driver->init_termios.c_iflag = IGNBRK | IGNPAR;
driver->init_termios.c_oflag = ONLCR | XTABS;
driver->init_termios.c_lflag = ISIG | ECHO;
driver->flags = TTY_DRIVER_REAL_RAW;
tty_set_operations(driver, &sclp_ops);
rc = tty_register_driver(driver);
if (rc) {
put_tty_driver(driver);
return rc;
}
sclp_tty_driver = driver;
return 0;
}
module_init(sclp_tty_init);