2005-04-17 00:20:36 +02:00
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/*
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* drivers/s390/char/sclp_vt220.c
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* SCLP VT220 terminal driver.
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*
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* S390 version
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* Copyright (C) 2003 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Peter Oberparleiter <Peter.Oberparleiter@de.ibm.com>
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/wait.h>
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#include <linux/timer.h>
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#include <linux/kernel.h>
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#include <linux/tty.h>
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#include <linux/tty_driver.h>
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[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 05:54:13 +01:00
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#include <linux/tty_flip.h>
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2005-04-17 00:20:36 +02:00
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#include <linux/sched.h>
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <linux/major.h>
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#include <linux/console.h>
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#include <linux/kdev_t.h>
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#include <linux/bootmem.h>
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#include <linux/interrupt.h>
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#include <linux/init.h>
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#include <asm/uaccess.h>
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#include "sclp.h"
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#define SCLP_VT220_PRINT_HEADER "sclp vt220 tty driver: "
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#define SCLP_VT220_MAJOR TTY_MAJOR
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#define SCLP_VT220_MINOR 65
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#define SCLP_VT220_DRIVER_NAME "sclp_vt220"
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#define SCLP_VT220_DEVICE_NAME "ttysclp"
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#define SCLP_VT220_CONSOLE_NAME "ttyS"
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#define SCLP_VT220_CONSOLE_INDEX 1 /* console=ttyS1 */
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#define SCLP_VT220_BUF_SIZE 80
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/* Representation of a single write request */
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struct sclp_vt220_request {
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struct list_head list;
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struct sclp_req sclp_req;
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int retry_count;
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};
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/* VT220 SCCB */
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struct sclp_vt220_sccb {
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struct sccb_header header;
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struct evbuf_header evbuf;
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};
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#define SCLP_VT220_MAX_CHARS_PER_BUFFER (PAGE_SIZE - \
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sizeof(struct sclp_vt220_request) - \
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sizeof(struct sclp_vt220_sccb))
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/* Structures and data needed to register tty driver */
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static struct tty_driver *sclp_vt220_driver;
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/* The tty_struct that the kernel associated with us */
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static struct tty_struct *sclp_vt220_tty;
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/* Lock to protect internal data from concurrent access */
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static spinlock_t sclp_vt220_lock;
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/* List of empty pages to be used as write request buffers */
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static struct list_head sclp_vt220_empty;
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/* List of pending requests */
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static struct list_head sclp_vt220_outqueue;
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/* Number of requests in outqueue */
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static int sclp_vt220_outqueue_count;
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/* Wait queue used to delay write requests while we've run out of buffers */
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static wait_queue_head_t sclp_vt220_waitq;
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/* Timer used for delaying write requests to merge subsequent messages into
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* a single buffer */
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static struct timer_list sclp_vt220_timer;
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/* Pointer to current request buffer which has been partially filled but not
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* yet sent */
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static struct sclp_vt220_request *sclp_vt220_current_request;
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/* Number of characters in current request buffer */
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static int sclp_vt220_buffered_chars;
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/* Flag indicating whether this driver has already been initialized */
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static int sclp_vt220_initialized = 0;
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/* Flag indicating that sclp_vt220_current_request should really
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* have been already queued but wasn't because the SCLP was processing
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* another buffer */
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static int sclp_vt220_flush_later;
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static void sclp_vt220_receiver_fn(struct evbuf_header *evbuf);
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static int __sclp_vt220_emit(struct sclp_vt220_request *request);
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static void sclp_vt220_emit_current(void);
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/* Registration structure for our interest in SCLP event buffers */
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static struct sclp_register sclp_vt220_register = {
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.send_mask = EvTyp_VT220Msg_Mask,
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.receive_mask = EvTyp_VT220Msg_Mask,
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.state_change_fn = NULL,
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.receiver_fn = sclp_vt220_receiver_fn
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};
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/*
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* Put provided request buffer back into queue and check emit pending
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* buffers if necessary.
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*/
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static void
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sclp_vt220_process_queue(struct sclp_vt220_request *request)
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{
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unsigned long flags;
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void *page;
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do {
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/* Put buffer back to list of empty buffers */
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page = request->sclp_req.sccb;
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spin_lock_irqsave(&sclp_vt220_lock, flags);
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/* Move request from outqueue to empty queue */
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list_del(&request->list);
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sclp_vt220_outqueue_count--;
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list_add_tail((struct list_head *) page, &sclp_vt220_empty);
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/* Check if there is a pending buffer on the out queue. */
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request = NULL;
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if (!list_empty(&sclp_vt220_outqueue))
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request = list_entry(sclp_vt220_outqueue.next,
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struct sclp_vt220_request, list);
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spin_unlock_irqrestore(&sclp_vt220_lock, flags);
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} while (request && __sclp_vt220_emit(request));
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if (request == NULL && sclp_vt220_flush_later)
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sclp_vt220_emit_current();
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wake_up(&sclp_vt220_waitq);
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/* Check if the tty needs a wake up call */
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if (sclp_vt220_tty != NULL) {
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tty_wakeup(sclp_vt220_tty);
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}
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}
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#define SCLP_BUFFER_MAX_RETRY 1
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/*
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* Callback through which the result of a write request is reported by the
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* SCLP.
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*/
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static void
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sclp_vt220_callback(struct sclp_req *request, void *data)
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{
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struct sclp_vt220_request *vt220_request;
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struct sclp_vt220_sccb *sccb;
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vt220_request = (struct sclp_vt220_request *) data;
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if (request->status == SCLP_REQ_FAILED) {
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sclp_vt220_process_queue(vt220_request);
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return;
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}
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sccb = (struct sclp_vt220_sccb *) vt220_request->sclp_req.sccb;
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/* Check SCLP response code and choose suitable action */
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switch (sccb->header.response_code) {
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case 0x0020 :
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break;
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case 0x05f0: /* Target resource in improper state */
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break;
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case 0x0340: /* Contained SCLP equipment check */
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if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
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break;
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/* Remove processed buffers and requeue rest */
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if (sclp_remove_processed((struct sccb_header *) sccb) > 0) {
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/* Not all buffers were processed */
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sccb->header.response_code = 0x0000;
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vt220_request->sclp_req.status = SCLP_REQ_FILLED;
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if (sclp_add_request(request) == 0)
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return;
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}
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break;
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case 0x0040: /* SCLP equipment check */
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if (++vt220_request->retry_count > SCLP_BUFFER_MAX_RETRY)
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break;
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sccb->header.response_code = 0x0000;
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vt220_request->sclp_req.status = SCLP_REQ_FILLED;
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if (sclp_add_request(request) == 0)
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return;
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break;
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default:
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break;
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}
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sclp_vt220_process_queue(vt220_request);
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}
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/*
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* Emit vt220 request buffer to SCLP. Return zero on success, non-zero
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* otherwise.
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*/
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static int
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__sclp_vt220_emit(struct sclp_vt220_request *request)
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{
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if (!(sclp_vt220_register.sclp_send_mask & EvTyp_VT220Msg_Mask)) {
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request->sclp_req.status = SCLP_REQ_FAILED;
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return -EIO;
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}
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request->sclp_req.command = SCLP_CMDW_WRITEDATA;
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request->sclp_req.status = SCLP_REQ_FILLED;
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request->sclp_req.callback = sclp_vt220_callback;
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request->sclp_req.callback_data = (void *) request;
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return sclp_add_request(&request->sclp_req);
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}
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/*
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* Queue and emit given request.
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*/
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static void
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sclp_vt220_emit(struct sclp_vt220_request *request)
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{
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unsigned long flags;
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int count;
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spin_lock_irqsave(&sclp_vt220_lock, flags);
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list_add_tail(&request->list, &sclp_vt220_outqueue);
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count = sclp_vt220_outqueue_count++;
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spin_unlock_irqrestore(&sclp_vt220_lock, flags);
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/* Emit only the first buffer immediately - callback takes care of
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* the rest */
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if (count == 0 && __sclp_vt220_emit(request))
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sclp_vt220_process_queue(request);
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}
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/*
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* Queue and emit current request. Return zero on success, non-zero otherwise.
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*/
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static void
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sclp_vt220_emit_current(void)
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{
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unsigned long flags;
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struct sclp_vt220_request *request;
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struct sclp_vt220_sccb *sccb;
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spin_lock_irqsave(&sclp_vt220_lock, flags);
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request = NULL;
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if (sclp_vt220_current_request != NULL) {
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sccb = (struct sclp_vt220_sccb *)
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sclp_vt220_current_request->sclp_req.sccb;
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/* Only emit buffers with content */
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if (sccb->header.length != sizeof(struct sclp_vt220_sccb)) {
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request = sclp_vt220_current_request;
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sclp_vt220_current_request = NULL;
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if (timer_pending(&sclp_vt220_timer))
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del_timer(&sclp_vt220_timer);
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}
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sclp_vt220_flush_later = 0;
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}
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spin_unlock_irqrestore(&sclp_vt220_lock, flags);
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if (request != NULL)
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sclp_vt220_emit(request);
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}
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#define SCLP_NORMAL_WRITE 0x00
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/*
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* Helper function to initialize a page with the sclp request structure.
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*/
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static struct sclp_vt220_request *
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sclp_vt220_initialize_page(void *page)
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{
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struct sclp_vt220_request *request;
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struct sclp_vt220_sccb *sccb;
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/* Place request structure at end of page */
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request = ((struct sclp_vt220_request *)
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((addr_t) page + PAGE_SIZE)) - 1;
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request->retry_count = 0;
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request->sclp_req.sccb = page;
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/* SCCB goes at start of page */
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sccb = (struct sclp_vt220_sccb *) page;
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memset((void *) sccb, 0, sizeof(struct sclp_vt220_sccb));
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sccb->header.length = sizeof(struct sclp_vt220_sccb);
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sccb->header.function_code = SCLP_NORMAL_WRITE;
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sccb->header.response_code = 0x0000;
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sccb->evbuf.type = EvTyp_VT220Msg;
|
|
|
|
sccb->evbuf.length = sizeof(struct evbuf_header);
|
|
|
|
|
|
|
|
return request;
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline unsigned int
|
|
|
|
sclp_vt220_space_left(struct sclp_vt220_request *request)
|
|
|
|
{
|
|
|
|
struct sclp_vt220_sccb *sccb;
|
|
|
|
sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
|
|
|
|
return PAGE_SIZE - sizeof(struct sclp_vt220_request) -
|
|
|
|
sccb->header.length;
|
|
|
|
}
|
|
|
|
|
|
|
|
static inline unsigned int
|
|
|
|
sclp_vt220_chars_stored(struct sclp_vt220_request *request)
|
|
|
|
{
|
|
|
|
struct sclp_vt220_sccb *sccb;
|
|
|
|
sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
|
|
|
|
return sccb->evbuf.length - sizeof(struct evbuf_header);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Add msg to buffer associated with request. Return the number of characters
|
|
|
|
* added.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
sclp_vt220_add_msg(struct sclp_vt220_request *request,
|
|
|
|
const unsigned char *msg, int count, int convertlf)
|
|
|
|
{
|
|
|
|
struct sclp_vt220_sccb *sccb;
|
|
|
|
void *buffer;
|
|
|
|
unsigned char c;
|
|
|
|
int from;
|
|
|
|
int to;
|
|
|
|
|
|
|
|
if (count > sclp_vt220_space_left(request))
|
|
|
|
count = sclp_vt220_space_left(request);
|
|
|
|
if (count <= 0)
|
|
|
|
return 0;
|
|
|
|
|
|
|
|
sccb = (struct sclp_vt220_sccb *) request->sclp_req.sccb;
|
|
|
|
buffer = (void *) ((addr_t) sccb + sccb->header.length);
|
|
|
|
|
|
|
|
if (convertlf) {
|
|
|
|
/* Perform Linefeed conversion (0x0a -> 0x0a 0x0d)*/
|
|
|
|
for (from=0, to=0;
|
|
|
|
(from < count) && (to < sclp_vt220_space_left(request));
|
|
|
|
from++) {
|
|
|
|
/* Retrieve character */
|
|
|
|
c = msg[from];
|
|
|
|
/* Perform conversion */
|
|
|
|
if (c == 0x0a) {
|
|
|
|
if (to + 1 < sclp_vt220_space_left(request)) {
|
|
|
|
((unsigned char *) buffer)[to++] = c;
|
|
|
|
((unsigned char *) buffer)[to++] = 0x0d;
|
|
|
|
} else
|
|
|
|
break;
|
|
|
|
|
|
|
|
} else
|
|
|
|
((unsigned char *) buffer)[to++] = c;
|
|
|
|
}
|
|
|
|
sccb->header.length += to;
|
|
|
|
sccb->evbuf.length += to;
|
|
|
|
return from;
|
|
|
|
} else {
|
|
|
|
memcpy(buffer, (const void *) msg, count);
|
|
|
|
sccb->header.length += count;
|
|
|
|
sccb->evbuf.length += count;
|
|
|
|
return count;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Emit buffer after having waited long enough for more data to arrive.
|
|
|
|
*/
|
|
|
|
static void
|
|
|
|
sclp_vt220_timeout(unsigned long data)
|
|
|
|
{
|
|
|
|
sclp_vt220_emit_current();
|
|
|
|
}
|
|
|
|
|
|
|
|
#define BUFFER_MAX_DELAY HZ/2
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Internal implementation of the write function. Write COUNT bytes of data
|
|
|
|
* from memory at BUF
|
|
|
|
* to the SCLP interface. In case that the data does not fit into the current
|
|
|
|
* write buffer, emit the current one and allocate a new one. If there are no
|
|
|
|
* more empty buffers available, wait until one gets emptied. If DO_SCHEDULE
|
|
|
|
* is non-zero, the buffer will be scheduled for emitting after a timeout -
|
|
|
|
* otherwise the user has to explicitly call the flush function.
|
|
|
|
* A non-zero CONVERTLF parameter indicates that 0x0a characters in the message
|
|
|
|
* buffer should be converted to 0x0a 0x0d. After completion, return the number
|
|
|
|
* of bytes written.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
__sclp_vt220_write(const unsigned char *buf, int count, int do_schedule,
|
|
|
|
int convertlf)
|
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
void *page;
|
|
|
|
int written;
|
|
|
|
int overall_written;
|
|
|
|
|
|
|
|
if (count <= 0)
|
|
|
|
return 0;
|
|
|
|
overall_written = 0;
|
|
|
|
spin_lock_irqsave(&sclp_vt220_lock, flags);
|
|
|
|
do {
|
|
|
|
/* Create a sclp output buffer if none exists yet */
|
|
|
|
if (sclp_vt220_current_request == NULL) {
|
|
|
|
while (list_empty(&sclp_vt220_empty)) {
|
|
|
|
spin_unlock_irqrestore(&sclp_vt220_lock,
|
|
|
|
flags);
|
|
|
|
if (in_interrupt())
|
|
|
|
sclp_sync_wait();
|
|
|
|
else
|
|
|
|
wait_event(sclp_vt220_waitq,
|
|
|
|
!list_empty(&sclp_vt220_empty));
|
|
|
|
spin_lock_irqsave(&sclp_vt220_lock, flags);
|
|
|
|
}
|
|
|
|
page = (void *) sclp_vt220_empty.next;
|
|
|
|
list_del((struct list_head *) page);
|
|
|
|
sclp_vt220_current_request =
|
|
|
|
sclp_vt220_initialize_page(page);
|
|
|
|
}
|
|
|
|
/* Try to write the string to the current request buffer */
|
|
|
|
written = sclp_vt220_add_msg(sclp_vt220_current_request,
|
|
|
|
buf, count, convertlf);
|
|
|
|
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.
|
|
|
|
*/
|
|
|
|
spin_unlock_irqrestore(&sclp_vt220_lock, flags);
|
|
|
|
sclp_vt220_emit_current();
|
|
|
|
spin_lock_irqsave(&sclp_vt220_lock, flags);
|
|
|
|
buf += written;
|
|
|
|
count -= written;
|
|
|
|
} while (count > 0);
|
|
|
|
/* Setup timer to output current console buffer after some time */
|
|
|
|
if (sclp_vt220_current_request != NULL &&
|
|
|
|
!timer_pending(&sclp_vt220_timer) && do_schedule) {
|
|
|
|
sclp_vt220_timer.function = sclp_vt220_timeout;
|
|
|
|
sclp_vt220_timer.data = 0UL;
|
|
|
|
sclp_vt220_timer.expires = jiffies + BUFFER_MAX_DELAY;
|
|
|
|
add_timer(&sclp_vt220_timer);
|
|
|
|
}
|
|
|
|
spin_unlock_irqrestore(&sclp_vt220_lock, flags);
|
|
|
|
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_vt220_write(struct tty_struct *tty, const unsigned char *buf, int count)
|
|
|
|
{
|
|
|
|
return __sclp_vt220_write(buf, count, 1, 0);
|
|
|
|
}
|
|
|
|
|
|
|
|
#define SCLP_VT220_SESSION_ENDED 0x01
|
|
|
|
#define SCLP_VT220_SESSION_STARTED 0x80
|
|
|
|
#define SCLP_VT220_SESSION_DATA 0x00
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Called by the SCLP to report incoming event buffers.
|
|
|
|
*/
|
|
|
|
static void
|
|
|
|
sclp_vt220_receiver_fn(struct evbuf_header *evbuf)
|
|
|
|
{
|
|
|
|
char *buffer;
|
|
|
|
unsigned int count;
|
|
|
|
|
|
|
|
/* Ignore input if device is not open */
|
|
|
|
if (sclp_vt220_tty == NULL)
|
|
|
|
return;
|
|
|
|
|
|
|
|
buffer = (char *) ((addr_t) evbuf + sizeof(struct evbuf_header));
|
|
|
|
count = evbuf->length - sizeof(struct evbuf_header);
|
|
|
|
|
|
|
|
switch (*buffer) {
|
|
|
|
case SCLP_VT220_SESSION_ENDED:
|
|
|
|
case SCLP_VT220_SESSION_STARTED:
|
|
|
|
break;
|
|
|
|
case SCLP_VT220_SESSION_DATA:
|
|
|
|
/* Send input to line discipline */
|
|
|
|
buffer++;
|
|
|
|
count--;
|
[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 05:54:13 +01:00
|
|
|
tty_insert_flip_string(sclp_vt220_tty, buffer, count);
|
2005-04-17 00:20:36 +02:00
|
|
|
tty_flip_buffer_push(sclp_vt220_tty);
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This routine is called when a particular tty device is opened.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
sclp_vt220_open(struct tty_struct *tty, struct file *filp)
|
|
|
|
{
|
|
|
|
if (tty->count == 1) {
|
|
|
|
sclp_vt220_tty = tty;
|
|
|
|
tty->driver_data = kmalloc(SCLP_VT220_BUF_SIZE, GFP_KERNEL);
|
|
|
|
if (tty->driver_data == NULL)
|
|
|
|
return -ENOMEM;
|
|
|
|
tty->low_latency = 0;
|
|
|
|
}
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This routine is called when a particular tty device is closed.
|
|
|
|
*/
|
|
|
|
static void
|
|
|
|
sclp_vt220_close(struct tty_struct *tty, struct file *filp)
|
|
|
|
{
|
|
|
|
if (tty->count == 1) {
|
|
|
|
sclp_vt220_tty = NULL;
|
|
|
|
kfree(tty->driver_data);
|
|
|
|
tty->driver_data = NULL;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* 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.
|
|
|
|
*
|
|
|
|
* NOTE: include/linux/tty_driver.h specifies that a character should be
|
|
|
|
* ignored if there is no room in the queue. This driver implements a different
|
|
|
|
* semantic in that it will block when there is no more room left.
|
|
|
|
*/
|
|
|
|
static void
|
|
|
|
sclp_vt220_put_char(struct tty_struct *tty, unsigned char ch)
|
|
|
|
{
|
|
|
|
__sclp_vt220_write(&ch, 1, 0, 0);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* 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_vt220_flush_chars(struct tty_struct *tty)
|
|
|
|
{
|
|
|
|
if (sclp_vt220_outqueue_count == 0)
|
|
|
|
sclp_vt220_emit_current();
|
|
|
|
else
|
|
|
|
sclp_vt220_flush_later = 1;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* 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.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
sclp_vt220_write_room(struct tty_struct *tty)
|
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
struct list_head *l;
|
|
|
|
int count;
|
|
|
|
|
|
|
|
spin_lock_irqsave(&sclp_vt220_lock, flags);
|
|
|
|
count = 0;
|
|
|
|
if (sclp_vt220_current_request != NULL)
|
|
|
|
count = sclp_vt220_space_left(sclp_vt220_current_request);
|
|
|
|
list_for_each(l, &sclp_vt220_empty)
|
|
|
|
count += SCLP_VT220_MAX_CHARS_PER_BUFFER;
|
|
|
|
spin_unlock_irqrestore(&sclp_vt220_lock, flags);
|
|
|
|
return count;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Return number of buffered chars.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
sclp_vt220_chars_in_buffer(struct tty_struct *tty)
|
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
struct list_head *l;
|
|
|
|
struct sclp_vt220_request *r;
|
|
|
|
int count;
|
|
|
|
|
|
|
|
spin_lock_irqsave(&sclp_vt220_lock, flags);
|
|
|
|
count = 0;
|
|
|
|
if (sclp_vt220_current_request != NULL)
|
|
|
|
count = sclp_vt220_chars_stored(sclp_vt220_current_request);
|
|
|
|
list_for_each(l, &sclp_vt220_outqueue) {
|
|
|
|
r = list_entry(l, struct sclp_vt220_request, list);
|
|
|
|
count += sclp_vt220_chars_stored(r);
|
|
|
|
}
|
|
|
|
spin_unlock_irqrestore(&sclp_vt220_lock, flags);
|
|
|
|
return count;
|
|
|
|
}
|
|
|
|
|
|
|
|
static void
|
|
|
|
__sclp_vt220_flush_buffer(void)
|
|
|
|
{
|
|
|
|
unsigned long flags;
|
|
|
|
|
|
|
|
sclp_vt220_emit_current();
|
|
|
|
spin_lock_irqsave(&sclp_vt220_lock, flags);
|
|
|
|
if (timer_pending(&sclp_vt220_timer))
|
|
|
|
del_timer(&sclp_vt220_timer);
|
|
|
|
while (sclp_vt220_outqueue_count > 0) {
|
|
|
|
spin_unlock_irqrestore(&sclp_vt220_lock, flags);
|
|
|
|
sclp_sync_wait();
|
|
|
|
spin_lock_irqsave(&sclp_vt220_lock, flags);
|
|
|
|
}
|
|
|
|
spin_unlock_irqrestore(&sclp_vt220_lock, flags);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Pass on all buffers to the hardware. Return only when there are no more
|
|
|
|
* buffers pending.
|
|
|
|
*/
|
|
|
|
static void
|
|
|
|
sclp_vt220_flush_buffer(struct tty_struct *tty)
|
|
|
|
{
|
|
|
|
sclp_vt220_emit_current();
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Initialize all relevant components and register driver with system.
|
|
|
|
*/
|
|
|
|
static int
|
|
|
|
__sclp_vt220_init(int early)
|
|
|
|
{
|
|
|
|
void *page;
|
|
|
|
int i;
|
|
|
|
|
|
|
|
if (sclp_vt220_initialized)
|
|
|
|
return 0;
|
|
|
|
sclp_vt220_initialized = 1;
|
|
|
|
spin_lock_init(&sclp_vt220_lock);
|
|
|
|
INIT_LIST_HEAD(&sclp_vt220_empty);
|
|
|
|
INIT_LIST_HEAD(&sclp_vt220_outqueue);
|
|
|
|
init_waitqueue_head(&sclp_vt220_waitq);
|
|
|
|
init_timer(&sclp_vt220_timer);
|
|
|
|
sclp_vt220_current_request = NULL;
|
|
|
|
sclp_vt220_buffered_chars = 0;
|
|
|
|
sclp_vt220_outqueue_count = 0;
|
|
|
|
sclp_vt220_tty = NULL;
|
|
|
|
sclp_vt220_flush_later = 0;
|
|
|
|
|
|
|
|
/* Allocate pages for output buffering */
|
|
|
|
for (i = 0; i < (early ? MAX_CONSOLE_PAGES : MAX_KMEM_PAGES); i++) {
|
|
|
|
if (early)
|
|
|
|
page = alloc_bootmem_low_pages(PAGE_SIZE);
|
|
|
|
else
|
|
|
|
page = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
|
|
|
|
if (!page)
|
|
|
|
return -ENOMEM;
|
|
|
|
list_add_tail((struct list_head *) page, &sclp_vt220_empty);
|
|
|
|
}
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static struct tty_operations sclp_vt220_ops = {
|
|
|
|
.open = sclp_vt220_open,
|
|
|
|
.close = sclp_vt220_close,
|
|
|
|
.write = sclp_vt220_write,
|
|
|
|
.put_char = sclp_vt220_put_char,
|
|
|
|
.flush_chars = sclp_vt220_flush_chars,
|
|
|
|
.write_room = sclp_vt220_write_room,
|
|
|
|
.chars_in_buffer = sclp_vt220_chars_in_buffer,
|
|
|
|
.flush_buffer = sclp_vt220_flush_buffer
|
|
|
|
};
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Register driver with SCLP and Linux and initialize internal tty structures.
|
|
|
|
*/
|
|
|
|
int __init
|
|
|
|
sclp_vt220_tty_init(void)
|
|
|
|
{
|
|
|
|
struct tty_driver *driver;
|
|
|
|
int rc;
|
|
|
|
|
|
|
|
/* Note: we're not testing for CONSOLE_IS_SCLP here to preserve
|
|
|
|
* symmetry between VM and LPAR systems regarding ttyS1. */
|
|
|
|
driver = alloc_tty_driver(1);
|
|
|
|
if (!driver)
|
|
|
|
return -ENOMEM;
|
|
|
|
rc = __sclp_vt220_init(0);
|
|
|
|
if (rc) {
|
|
|
|
put_tty_driver(driver);
|
|
|
|
return rc;
|
|
|
|
}
|
|
|
|
rc = sclp_register(&sclp_vt220_register);
|
|
|
|
if (rc) {
|
|
|
|
printk(KERN_ERR SCLP_VT220_PRINT_HEADER
|
|
|
|
"could not register tty - "
|
|
|
|
"sclp_register returned %d\n", rc);
|
|
|
|
put_tty_driver(driver);
|
|
|
|
return rc;
|
|
|
|
}
|
|
|
|
|
|
|
|
driver->owner = THIS_MODULE;
|
|
|
|
driver->driver_name = SCLP_VT220_DRIVER_NAME;
|
|
|
|
driver->name = SCLP_VT220_DEVICE_NAME;
|
|
|
|
driver->major = SCLP_VT220_MAJOR;
|
|
|
|
driver->minor_start = SCLP_VT220_MINOR;
|
|
|
|
driver->type = TTY_DRIVER_TYPE_SYSTEM;
|
|
|
|
driver->subtype = SYSTEM_TYPE_TTY;
|
|
|
|
driver->init_termios = tty_std_termios;
|
|
|
|
driver->flags = TTY_DRIVER_REAL_RAW;
|
|
|
|
tty_set_operations(driver, &sclp_vt220_ops);
|
|
|
|
|
|
|
|
rc = tty_register_driver(driver);
|
|
|
|
if (rc) {
|
|
|
|
printk(KERN_ERR SCLP_VT220_PRINT_HEADER
|
|
|
|
"could not register tty - "
|
|
|
|
"tty_register_driver returned %d\n", rc);
|
|
|
|
put_tty_driver(driver);
|
|
|
|
return rc;
|
|
|
|
}
|
|
|
|
sclp_vt220_driver = driver;
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
module_init(sclp_vt220_tty_init);
|
|
|
|
|
|
|
|
#ifdef CONFIG_SCLP_VT220_CONSOLE
|
|
|
|
|
|
|
|
static void
|
|
|
|
sclp_vt220_con_write(struct console *con, const char *buf, unsigned int count)
|
|
|
|
{
|
|
|
|
__sclp_vt220_write((const unsigned char *) buf, count, 1, 1);
|
|
|
|
}
|
|
|
|
|
|
|
|
static struct tty_driver *
|
|
|
|
sclp_vt220_con_device(struct console *c, int *index)
|
|
|
|
{
|
|
|
|
*index = 0;
|
|
|
|
return sclp_vt220_driver;
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This routine is called from panic when the kernel is going to give up.
|
|
|
|
* We have to make sure that all buffers will be flushed to the SCLP.
|
|
|
|
* Note that this function may be called from within an interrupt context.
|
|
|
|
*/
|
|
|
|
static void
|
|
|
|
sclp_vt220_con_unblank(void)
|
|
|
|
{
|
|
|
|
__sclp_vt220_flush_buffer();
|
|
|
|
}
|
|
|
|
|
|
|
|
/* Structure needed to register with printk */
|
|
|
|
static struct console sclp_vt220_console =
|
|
|
|
{
|
|
|
|
.name = SCLP_VT220_CONSOLE_NAME,
|
|
|
|
.write = sclp_vt220_con_write,
|
|
|
|
.device = sclp_vt220_con_device,
|
|
|
|
.unblank = sclp_vt220_con_unblank,
|
|
|
|
.flags = CON_PRINTBUFFER,
|
|
|
|
.index = SCLP_VT220_CONSOLE_INDEX
|
|
|
|
};
|
|
|
|
|
|
|
|
static int __init
|
|
|
|
sclp_vt220_con_init(void)
|
|
|
|
{
|
|
|
|
int rc;
|
|
|
|
|
|
|
|
if (!CONSOLE_IS_SCLP)
|
|
|
|
return 0;
|
|
|
|
rc = __sclp_vt220_init(1);
|
|
|
|
if (rc)
|
|
|
|
return rc;
|
|
|
|
/* Attach linux console */
|
|
|
|
register_console(&sclp_vt220_console);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
console_initcall(sclp_vt220_con_init);
|
|
|
|
#endif /* CONFIG_SCLP_VT220_CONSOLE */
|
|
|
|
|