Commit Graph

16 Commits

Author SHA1 Message Date
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
Tobias Klauser fe971071a8 [PATCH] drivers/char: Use ARRAY_SIZE macro
Use ARRAY_SIZE macro instead of sizeof(x)/sizeof(x[0]) and remove
duplicates of ARRAY_SIZE.

Signed-off-by: Tobias Klauser <tklauser@nuerscht.ch>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-10 08:01:56 -08:00
Dominik Brodowski f8cfa618dc [PATCH] pcmcia: unify attach, EVENT_CARD_INSERTION handlers into one probe callback
Unify the EVENT_CARD_INSERTION and "attach" callbacks to one unified
probe() callback. As all in-kernel drivers are changed to this new
callback, there will be no temporary backwards-compatibility. Inside a
probe() function, each driver _must_ set struct pcmcia_device
*p_dev->instance and instance->handle correctly.

With these patches, the basic driver interface for 16-bit PCMCIA drivers
now has the classic four callbacks known also from other buses:

        int (*probe)            (struct pcmcia_device *dev);
        void (*remove)          (struct pcmcia_device *dev);

        int (*suspend)          (struct pcmcia_device *dev);
        int (*resume)           (struct pcmcia_device *dev);

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2006-01-06 00:03:24 +01:00
Dominik Brodowski b463581154 [PATCH] pcmcia: remove dev_list from drivers
The linked list of devices managed by each PCMCIA driver is, in very most
cases, unused. Therefore, remove it from many drivers.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2006-01-06 00:03:20 +01:00
Dominik Brodowski cc3b4866be [PATCH] pcmcia: unify detach, REMOVAL_EVENT handlers into one remove callback
Unify the "detach" and REMOVAL_EVENT handlers to one "remove" function.
Old functionality is preserved, for the moment.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2006-01-06 00:03:10 +01:00
Dominik Brodowski 98e4c28b7e [PATCH] pcmcia: new suspend core
Move the suspend and resume methods out of the event handler, and into
special functions. Also use these functions for pre- and post-reset, as
almost all drivers already do, and the remaining ones can easily be
converted.

Bugfix to include/pcmcia/ds.c
Signed-off-by: Andrew Morton <akpm@osdl.org>

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2006-01-05 23:59:02 +01:00
Al Viro c4aa02eb39 [PATCH] cm4000_cs: __user annotations
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-12-15 10:04:30 -08:00
Harald Welte c1986ee9be [PATCH] New Omnikey Cardman 4000 driver
Add new Omnikey Cardman 4000 smartcard reader driver

Signed-off-by: Harald Welte <laforge@gnumonks.org>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-13 18:14:10 -08:00
Harald Welte 77c44ab1d8 [PATCH] New Omnikey Cardman 4040 driver
Add new Omnikey Cardman 4040 smartcard reader driver

Signed-off-by: Harald Welte <laforge@gnumonks.org>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-13 18:14:10 -08:00
Jesper Juhl 735d5661d5 [PATCH] kfree cleanup: drivers/char
This is the drivers/char/ part of the big kfree cleanup patch.

Remove pointless checks for NULL prior to calling kfree() in drivers/char/.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 07:54:02 -08:00
Paul Fulghum a7482a2e77 [PATCH] synclink_cs add statistics clear
Add ability to clear statistics.

Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:22 -07:00
Dominik Brodowski 44670d2b50 [PATCH] pcmcia: remove references to pcmcia/version.h
As a follow-up, remove the inclusion of pcmcia/version.h in many files.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-07 18:24:07 -07:00
Dominik Brodowski 1e212f3645 [PATCH] pcmcia: move event handler
Move the "event handler" to struct pcmcia_driver -- the unified event handler
will disappear really soon, but switching it to struct pcmcia_driver in the
meantime allows for better "step-by-step" patches.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-07-07 18:24:05 -07:00
Dominik Brodowski 0c7ab67602 [PATCH] pcmcia: synclink_cs IRQ_INFO2_INFO is gone
Remove the IRQ_INFO2_VALID flag in synclink_cs -- I overlooked it when
removing all other users in PCMCIA drivers for 2.6.11.  Thanks to Marcelo
Tosatti for noticing it.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 18:03:21 -07:00
Dominik Brodowski 4af48c8c16 [PATCH] pcmcia: id_table for synclink_cs.c
Add pcmcia_device_id table.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-27 18:03:17 -07:00
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00