Commit Graph

31 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
Dave Jones a61c2d78ce [SERIAL] Make the number of UARTs registered configurable.
Also add a nr_uarts module option to the 8250 code to override
this, up to a maximum of CONFIG_SERIAL_8250_NR_UARTS

This should appease people who complain about a proliferation
of /dev/ttyS & /sysfs nodes whilst at the same time allowing
a single kernel image to support the rarer occasions of
lots of devices.

Signed-off-by: Dave Jones <davej@redhat.com>
2006-01-07 23:18:19 +00:00
Russell King ea8874dc38 [SERIAL] Remove _INLINE_
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-04 19:43:24 +00:00
Russell King 45e2460192 [SERIAL] Move interrupt-time spinlocking inside serial8250_handle_port()
All call sites for serial8250_handle_port() acquired the port spinlock
and released it afterwards.  This is a needless duplication of code.
Move the spinlocking inside serial8250_handle_port().

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-04 19:19:06 +00:00
Russell King 50aec3b561 [SERIAL] Use uart_match_port() to find a matching port in find_port()
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-04 18:13:03 +00:00
Russell King 2af7cd68f1 [Serial] Don't miss modem status changes
Reading the MSR register on 8250-compatible UARTs results in any
modem status interrupts being cleared.  To avoid missing any
status changes, arrange for get_mctrl() to read the current
status via check_modem_status(), which will process any pending
state changes for us.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2006-01-04 16:55:09 +00:00
Arjan van de Ven cb3592be27 [SERIAL] mark several serial tables const
This patch marks a few serial data structures const, moving them to
.rodata where they won't false-share cachelines with things that get
written to.

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-28 21:04:11 +00:00
Lennert Buytenhek 5c8c755ce5 [SERIAL] don't disable xscale serial ports after autoconfig
xscale-type UARTs have an extra bit (UUE) in the IER register that has
to be written as 1 to enable the UART.  At the end of autoconfig() in
drivers/serial/8250.c, the IER register is unconditionally written as
zero, which turns off the UART, and makes any subsequent printch() hang
the box.

Since other 8250-type UARTs don't have this enable bit and are thus
always 'enabled' in this sense, it can't hurt to enable xscale-type
serial ports all the time as well.  The attached patch changes the
autoconfig() exit path to see if the port has an UUE enable bit, and if
yes, to write UUE=1 instead of just putting a zero into IER, using the
same test as is used at the beginning of serial8250_console_write().

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-12 21:58:05 +00:00
Russell King 3ae5eaec1d [DRIVER MODEL] Convert platform drivers to use struct platform_driver
This allows us to eliminate the casts in the drivers, and eventually
remove the use of the device_driver function pointer methods for
platform device drivers.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-11-09 22:32:44 +00:00
Andrew Morton 78512ece14 [PATCH] serial console: touch NMI watchdog
Large console spews from IRQ or local_irq_disable() sections can cause the NMI
watchdog to go off.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 07:53:35 -08:00
Pantelis Antoniou 21c614a789 [SERIAL] Support Au1x00 8250 UARTs using the generic 8250 driver.
The offsets of the registers are in a different place, and
some parts cannot handle a full set of modem control signals.

Signed-off-by: Pantelis Antoniou <pantelis@embeddedalley.ocm>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-11-06 09:07:03 +00:00
Russell King d052d1beff Create platform_device.h to contain all the platform device details.
Convert everyone who uses platform_bus_type to include
linux/platform_device.h.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-10-29 19:07:23 +01:00
Russell King 9480e307cd [PATCH] DRIVER MODEL: Get rid of the obsolete tri-level suspend/resume callbacks
In PM v1, all devices were called at SUSPEND_DISABLE level.  Then
all devices were called at SUSPEND_SAVE_STATE level, and finally
SUSPEND_POWER_DOWN level.  However, with PM v2, to maintain
compatibility for platform devices, I arranged for the PM v2
suspend/resume callbacks to call the old PM v1 suspend/resume
callbacks three times with each level in order so that existing
drivers continued to work.

Since this is obsolete infrastructure which is no longer necessary,
we can remove it.  Here's an (untested) patch to do exactly that.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2005-10-28 09:52:56 -07:00
Russell King 6f0d618f0e [SERIAL] Spelling fix in 8250.c
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-09-09 16:17:58 +01:00
Russell King 6df29debb7 [SERIAL] Use an enum for serial8250 platform device IDs
Rather than hard-coding the platform device IDs, enumerate them.
We don't particularly care about the actual ID we get, just as
long as they're unique.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-09-08 16:04:41 +01:00
Sascha Hauer 0f302dc354 [ARM] 2866/1: add i.MX set_mctrl / get_mctrl functions
Patch from Sascha Hauer

This patch adds support for setting and getting RTS / CTS via
set_mtctrl / get_mctrl functions.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-08-31 21:48:47 +01:00
Russell King b129a8ccd5 [SERIAL] Clean up and fix tty transmission start/stoping
The start_tx and stop_tx methods were passed a flag to indicate
whether the start/stop was from the tty start/stop callbacks, and
some drivers used this flag to decide whether to ask the UART to
immediately stop transmission (where the UART supports such a
feature.)

There are other cases when we wish this to occur - when CTS is
lowered, or if we change from soft to hard flow control and CTS
is inactive.  In these cases, this flag was false, and we would
allow the transmitter to drain before stopping.

There is really only one case where we want to let the transmitter
drain before disabling, and that's when we run out of characters
to send.

Hence, re-jig the start_tx and stop_tx methods to eliminate this
flag, and introduce new functions for the special "disable and
allow transmitter to drain" case.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-08-31 10:12:14 +01:00
Russell King 44454bcdb9 [PATCH] Serial: Fix small CONFIG_SERIAL_8250_NR_UARTS
If CONFIG_SERIAL_8250_NR_UARTS is smaller than the array size in
asm/serial.h, we trampled on memory which wasn't ours.  Take our
big boots away by limiting the number of ports initialised to the
smaller of ...NR_UARTS and the array size.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-30 22:41:22 +01:00
Russell King 026d02a236 [PATCH] Serial: Split 8250 port table (part 2)
Remove legacy ISA serial ports for Accent, Boca, Fourport, Hub6 and MCA
from the architecture specific serial.h include.

The only ports which remain in asm-*/serial.h are the platform specific
entries.  These should really be converted by platform maintainers to
use a platform device, such as can be found in
arch/arm/mach-footbridge/isa.c

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-29 18:45:19 +01:00
Russell King e763b90c41 [PATCH] Serial: Disable OX950 transmitter for flow control
Disable the transmitter whenever we want to prevent characters
being transmitted by flow control.  However, if we run out of
characters to send and want to only disable the TX interrupt,
allow that scenario.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-29 18:41:51 +01:00
Russell King c5f4644e6c [PATCH] Serial: Adjust serial locking
This patch changes the way serial ports are locked when getting modem
status.  This change is necessary because we will need to atomically
read the modem status and take action depending on the CTS status.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-29 09:42:38 +01:00
Russell King ec9f47cd6a [PATCH] Serial: Split 8250 port table
Add separate files for the different 8250 ISA-based serial boards.

Looking across all the various architectures, it seems reasonable that
we can key the availability of the configuration options for these
beasts to the bus-related symbols (iow, CONFIG_ISA).  We also standardise
the base baud/uart clock rate for these boards - I'm sure that isn't
architecture specific, but is solely dependent on the crystal fitted
on the board (which should be the same no matter what type of machine
its fitted into.)

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-27 11:12:54 +01:00
Russell King 0a8b80c52f [PATCH] Serial: Eliminate magic numbers
Use the existing macros instead.

Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-24 19:48:22 +01:00
Russell King 67f7654ea1 [PATCH] Serial: Bugs are not capabilities
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-23 22:26:43 +01:00
Russell King 55d3b282b9 [PATCH] Serial: Mobility's 16550A ports need a helping hand
The Mobility 16550A serial ports don't behave the same as standard
16550A ports, and need a helping hand to get them going once the
transmitter has drained and been disabled.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-23 15:05:41 +01:00
Russell King 4ba5e35daa [PATCH] Serial: Convert 8250 revision-based bug fixes to bug bitmask
For some 8250 port types, we used to check the type of the port, and
then determine whether the chip revision means the device is buggy.
Instead, introduce a bit array, and set the appropriate bit(s) when
we discover a buggy device.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-06-23 10:43:04 +01:00
David Woodhouse 857dde2e79 When we detect that a 16550 was in fact part of a NatSemi SuperIO chip
with high-speed mode enabled, we switch it to high-speed mode so that
baud_base becomes 921600. However, we also need to multiply the baud
divisor by 8 at the same time, in case it's already in use as a console.

Signed-off-by: David Woodhouse
Acked-by: Tom Rini
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2005-05-21 15:52:23 +01:00
Russell King 05ab301463 [PATCH] Serial: Add uart_insert_char()
Add uart_insert_char(), which handles inserting characters into the
flip buffer.  This helper function handles the correct semantics
for handling overrun in addition to inserting normal characters.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>
2005-05-09 23:21:59 +01:00
Adrian Bunk 408b664a7d [PATCH] make lots of things static
Another large rollup of various patches from Adrian which make things static
where they were needlessly exported.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-01 08:59:29 -07:00
Russell King 23907eb8c2 [PATCH] serial: fix comments in 8250.c
Fix the formatting of some comments in 8250.c, and add a note that the
register_serial / unregister_serial shouldn't be used in new code.

We do this here in preference to adding to linux/serial.h, since that is used
by a number of non-8250 drivers which pretend to be 8250.  It is not known
whether it would be appropriate to do so.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16 15:26:39 -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