struct uart_8250_port contains mcr_mask and mcr_force members whose
sole purpose is to work around an Alpha-specific quirk. This code
doesn't belong in the core where it is executed by everyone else,
so move it to a proper ->set_mctrl callback which is used on the
affected Alpha machine only.
The quirk was introduced in January 1995:
https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/diff/drivers/char/serial.c?h=1.1.83
The members in struct uart_8250_port were added in 2002:
https://git.kernel.org/history/history/c/4524aad27854
The quirk applies to non-PCI Alphas and arch/alpha/Kconfig specifies
"select FORCE_PCI if !ALPHA_JENSEN". So apparently the only affected
machine is the EISA-based Jensen that Linus was working on back then:
https://lore.kernel.org/all/CAHk-=wj1JWZ3sCrGz16nxEj7=0O+srMg6Ah3iPTDXSPKEws_SA@mail.gmail.com/
Up until now the quirk is not applied unless CONFIG_PCI is disabled.
If users forget to do that or run a generic Alpha kernel, the serial
ports aren't usable on Jensen. Avoid by confining the quirk to
CONFIG_ALPHA_JENSEN instead of !CONFIG_PCI. On generic Alpha kernels,
auto-detect at runtime whether the quirk needs to be applied.
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Ulrich Teichert <krypton@ulrich-teichert.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/b83d069cb516549b8a5420e097bb6bdd806f36fc.1640695609.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After the previous patch, we can make port passed to
serial8250_find_match_or_unused const. And then we can make const also
port of serial8250_register_8250_port.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210519072153.3859-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some platforms can be designed in a way so the UART port reference clock
might be asynchronously changed at some point. In Baikal-T1 SoC this may
happen due to the reference clock being shared between two UART ports, on
the Allwinner SoC the reference clock is derived from the CPU clock, so
any CPU frequency change should get to be known/reflected by/in the UART
controller as well. But it's not enough to just update the
uart_port->uartclk field of the corresponding UART port, the 8250
controller reference clock divisor should be altered so to preserve
current baud rate setting. All of these things is done in a coherent
way by calling the serial8250_update_uartclk() method provided in this
patch. Though note that it isn't supposed to be called from within the
UART port callbacks because the locks using to the protect the UART port
data are already taken in there.
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Link: https://lore.kernel.org/r/20200723003357.26897-2-Sergey.Semin@baikalelectronics.ru
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Doing any kind of power management for kernel console is really bad idea.
First of all, it runs in poll and atomic mode. This fact attaches a limitation
on the functions that might be called. For example, pm_runtime_get_sync() might
sleep and thus can't be used. This call needs, for example, to bring the device
to powered on state on the system, where the power on sequence may require
on-atomic operations, such as Intel Cherrytrail with ACPI enumerated UARTs.
That said, on ACPI enabled platforms it might even call firmware for a job.
On the other hand pm_runtime_get() doesn't guarantee that device will become
powered on fast enough.
Besides that, imagine the case when console is about to print a kernel Oops and
it's powered off. In such an emergency case calling the complex functions is
not the best what we can do, taking into consideration that user wants to see
at least something of the last kernel word before it passes away.
Here we modify the 8250 console code to prevent runtime power management.
Note, there is a behaviour change for OMAP boards. It will require to detach
kernel console to become idle.
Link: https://lists.openwall.net/linux-kernel/2018/09/29/65
Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200217114016.49856-6-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit e490c9144c ("tty: Add software emulated RS485 support for 8250")
introduced support to use RTS as an rs485 Transmit Enable signal.
So far the only drivers taking advantage of it are 8250_omap.c and
8250_of.c.
We're about to make use of the feature in 8250_bcm2835aux.c as well.
The bcm2835aux differs from omap chips by inverting the meaning of RTS
in the MCR register. Moreover, omap achieves half-duplex mode by
disabling the RX interrupt and clearing the RX FIFO when TX stops.
The bcm2835aux requires disabling the receiver instead.
Support these behavioral differences by generalizing the rs485 emulation:
Introduce ->rs485_start_tx() and ->rs485_stop_tx() callbacks in struct
uart_8250_port, provide generic implementations containing the existing
code and use them as callbacks in 8250_omap.c and 8250_of.c.
start_tx_rs485() is idempotent in that it recognizes whether RTS is
already asserted. Achieve the same by introducing a tx_stopped flag in
struct uart_8250_em485. This may even perform a little better on arches
where memory access is faster than mmio access.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Matwey V. Kornilov <matwey@sai.msu.ru>
Link: https://lore.kernel.org/r/5ac0464ae4414708e723a1e0d52b0c1b2bd41b9b.1582895077.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The SUPPORT_SYSRQ ifdeffery is not nice as:
- May create misunderstanding about sizeof(struct uart_port) between
different objects
- Prevents moving functions from serial_core.h
- Reduces readability (well, it's ifdeffery - it's hard to follow)
In order to remove SUPPORT_SYSRQ, has_sysrq variable has been added.
Initialise it in driver's probe and remove ifdeffery.
In contrast to 8250/8250_of, legacy_serial on powerpc does fill
(struct plat_serial8250_port). The reason is likely that it's done on
device_initcall(), not on probe. So, 8250_core is not yet probed.
Propagate value from platform_device on 8250 probe - in case powepc
legacy driver it's initialized on initcall, in case 8250_of it will be
initialized later on of_platform_serial_setup().
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-6-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.
Changed by Stefan:
Only call mctrl_gpio_init(), if the device has no ACPI companion device
to not break existing ACPI based systems. Also only use the mctrl_gpio_
functions when "gpios" is available.
Use MSR / MCR <-> TIOCM wrapper functions.
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Tested-by: Yegor Yefremov <yegorslists@googlemail.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Giulio Benetti <giulio.benetti@micronovasrl.com>
Cc: Yegor Yefremov <yegorslists@googlemail.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 3029 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When a serial port gets faulty or gets flooded with inputs, its interrupt
handler starts to work double time to get the characters to the workqueue
for the tty layer to handle them. When this busy time on the serial/tty
subsystem happens during boot, where it is also busy on the userspace
trying to initialise, some processes can continuously get preempted
and will be on hold until the interrupts subside.
The fix is to backoff on processing received characters for a specified
amount of time when an input overrun is seen (received a new character
before the previous one is processed). This only stops receive and will
continue to transmit characters to serial port. After the backoff period
is done, it receive will be re-enabled. This is optional and will only
be enabled by setting 'overrun-throttle-ms' in the dts.
Signed-off-by: Darwin Dingel <darwin.dingel@alliedtelesis.co.nz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some drivers could call serial8250_do_set_divisor() to complete its
own set_divisor routine. Export this symbol for code reusing.
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, we export serial8250_rx_chars, which does a whole bunch of
reads from the 8250 data register, without any form of flow control
between reads.
An upcoming change to the aspeed vuart driver implements more
fine-grained flow control in the interrupt handler, requiring
character-at-a-time control over the rx path.
This change exports serial8250_read_char to allow this.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Tested-by: Eddie James <eajames@linux.vnet.ibm.com>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Previously the timers where based on the classic timers, giving a too
coarse resolution on systems with configs of less than 1000 HZ.
This patch changes the rs485 timers to hrtimers.
Signed-off-by: Rafael Gago Castano <rgc@hms.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Expose set_ldisc() function so that it can be overridden with a
platform specific implementation.
Signed-off-by: Ed Blake <ed.blake@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add an IrDA UART capability flag and change the type of
uart_8250_port.capabilities to be u32 rather than unsigned short to
accommodate the additional flag.
Signed-off-by: Ed Blake <ed.blake@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Serial console is broken in v4.8-rcX. Mika and I independently bisected down to
commit 4ef03d3287 ("tty/serial/8250: use mctrl_gpio helpers").
Since neither author nor anyone else didn't propose a solution we better revert
it for now.
This reverts commit 4ef03d3287.
Link: https://lkml.kernel.org/r/20160809130229.GN1729@lahna.fi.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.
Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Exposes get_mctrl() function so that it can be overriden with platform
specific implementation.
Signed-off-by: Wan Ahmad Zainie <wan.ahmad.zainie.wan.mohamad@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Implementation of software emulation of RS485 direction handling is based
on omap_serial driver.
Before and after transmission RTS is set to the appropriate value.
Note that before calling serial8250_em485_init() the caller has to
ensure that UART will interrupt when shift register empty. Otherwise,
emultaion cannot be used.
Both serial8250_em485_init() and serial8250_em485_destroy() are
idempotent functions.
Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit ed71871bed ("tty/8250_early: Turn serial_in/serial_out into
weak symbols") made these routines weak to allow platform specific
Big endian override
However recent updates to core, specifically ebc5e20082 ("serial:
of_serial: Support big-endian register accesses") and 6e63be3fee
("serial: earlycon: Add support for big-endian MMIO accesses") means
that round about way to overide the early serial accessors is no longer
needed.
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Kevin Cernekee <cernekee@gmail.com>
Acked-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The header file, include/linux/serial_8250.h, contains references to
UART_LSR_BRK_ERROR_BITS and UART_MSR_ANY_DELTA that are defined in
<linux/serial_reg.h>.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Prepare for 8250 split; separate RSA probe and resource management
from base port operations. Override base port operations for the
config_port(), request_port() and release_port() methods to
implement the optional RSA probe and resource management only in
the universal/legacy 8250 driver.
Introduce 'probe' flags for 8250 ports, which allows drivers higher
up the driver stack to enable optional probes.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Prepare for 8250 split; decouple irq setup/teardown and handler from
core port operations.
Introduce setup_irq() and release_irq() 8250 driver methods; the 8250
core will use these methods to install and remove irq handling for
the given 8250 port.
Refactor irq chain linking/unlinking from 8250 core into
univ8250_setup_irq()/univ8250_release_irq() for the universal 8250 driver.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
setup_earlycon() will now match and register the desired earlycon
from the param string (as if 'earlycon=...' had been set on the
command line). Use setup_earlycon() from existing arch call sites
which start an earlycon directly.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add match() method to struct console which allows the console to
perform console command line matching instead of (or in addition to)
default console matching (ie., by fixed name and index).
The match() method returns 0 to indicate a successful match; normal
console matching occurs if no match() method is defined or the
match() method returns non-zero. The match() method is expected to set
the console index if required.
Re-implement earlycon-to-console-handoff with direct matching of
"console=uart|uart8250,..." to the 8250 ttyS console.
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When using no_console_suspend, the serial console may be powered off
anyway during system sleep. Upon resume, the port may be in its default
power-on state, but is expected to continue console i/o before the device
has received its pm callback. The resultant garbage i/o can cause all
kinds of havoc on the remote end.
Use the scratch register as a canary to discover if the console
has been powered-off. Write a non-zero value to the scratch register
at port suspend and reprogram the port before any console i/o if the
scratch register != canary before port resume.
This workaround is disabled for omap_8250 (which uses different divisor
programming).
Credit to Doug Anderson <dianders@chromium.org> for the idea of using
the scratch register canary to discover port power-down.
Cc: Doug Anderson <dianders@chromium.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The OMAP3 UART ignores MCR[1] (ie., UART_MCR_RTS) when in autoRTS
mode (UPF_HARD_FLOW + CRTSCTS). This makes it impossible for either
the serial core or userspace to manually flow control the sender.
Disable autoRTS mode when RTS is lowered and restore the previous
mode when RTS is raised.
Note that the OMAP3 UART provides no mechanism for switching from
autoRTS mode without corrupting incoming data; to access the
necessary register, the line control settings must be set to 8-e-2
and thus any data received during that time will be interpreted with
those settings. This corruption has been observed in practice.
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There is no more users for this functions. All the 8250 drivers are
using the rs485 handler on serial_core instead.
Reviewed-by: Alan Cox <alan@linux.intel.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The kbuild test robot wrote me:
| make.cross ARCH=powerpc
|>> ERROR: ".__xchg_called_with_bad_pointer" [drivers/tty/serial/8250/8250.ko] undefined!
The generic implementation of xchg() on arm and x86 works for variables of
size one bye (char). According to the report powerpc does not support
xchg() for one byte sized variables and looking further it seems also to
be the same case for sparc and tile (or for 10 out of 26 architectures
which provide a custom implementation).
For that reason I increase the size of the variable from one to four
bytes to get it work on powerpc (and the others).
Reported-By: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
While comparing the OMAP-serial and the 8250 part of this I noticed that
the latter does not use run time-pm. Here are the pieces. It is
basically a get before first register access and a last_busy + put after
last access. This has to be enabled from userland _and_ UART_CAP_RPM is
required for this.
The runtime PM can usually work transparently in the background however
there is one exception to this: After serial8250_tx_chars() completes
there still may be unsent bytes in the FIFO (depending on CPU speed vs
baud rate + flow control). Even if the TTY-buffer is empty we do not
want RPM to disable the device because it won't send the remaining
bytes. Instead we leave serial8250_tx_chars() with RPM enabled and wait
for the FIFO empty interrupt. Once we enter serial8250_tx_chars() with
an empty buffer we know that the FIFO is empty and since we are not going
to send anything, we can disable the device.
That xchg() is to ensure that serial8250_tx_chars() can be called
multiple times and only the first invocation will actually invoke the
runtime PM function. So that the last invocation of __stop_tx() will
disable runtime pm.
NOTE: do not enable RPM on the device unless you know what you do! If
the device goes idle, it won't be woken up by incomming RX data _unless_
there is a wakeup irq configured which is usually the RX pin configure
for wakeup via the reset module. The RX activity will then wake up the
device from idle. However the first character is garbage and lost. The
following bytes will be received once the device is up in time. On the
beagle board xm (omap3) it takes approx 13ms from the first wakeup byte
until the first byte that is received properly if the device was in
core-off.
v5…v8:
- drop RPM from serial8250_set_mctrl() it will be used in
restore path which already has RPM active and holds
dev->power.lock
v4…v5:
- add a wrapper around rpm function and introduce UART_CAP_RPM
to ensure RPM put is invoked after the TX FIFO is empty.
v3…v4:
- added runtime to the console code
- removed device_may_wakeup() from serial8250_set_sleep()
Cc: mika.westerberg@linux.intel.com
Reviewed-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The OMAP version of the 8250 can actually use 1:1 serial8250_startup().
However it needs to be extended by a wake up irq which should to be
requested & enabled at ->startup() time and disabled at ->shutdown() time.
v2…v3: properly copy callbacks
v1…v2: add shutdown callback
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch allow the users of the 8250 infrastructure to define a
handler for RS485 configration.
If no handler is defined the 8250 driver will work as usual.
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Acked-by: Alan Cox <alan@linux.intel.com>
--
v2:Change suggested by Alan "One Thousand Gnomes":
- Move rs485 structure further down on the uart_8250_port structure
drivers/tty/serial/8250/8250_core.c | 39 +++++++++++++++++++++++++++++++++++++
include/linux/serial_8250.h | 3 +++
2 files changed, 42 insertions(+)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add tunable RX interrupt trigger I/F of FIFO buffers.
Serial devices are used as not only message communication devices but control
or sending communication devices. For the latter uses, normally small data
will be exchanged, so user applications want to receive data unit as soon as
possible for real-time tendency. If we have a sensor which sends a 1 byte data
each time and must control a device based on the sensor feedback, the RX
interrupt should be triggered for each data.
According to HW specification of serial UART devices, RX interrupt trigger
can be changed, but the trigger is hard-coded. For example, RX interrupt trigger
in 16550A can be set to 1, 4, 8, or 14 bytes for HW, but current driver sets
the trigger to only 8bytes.
This patch makes some devices change RX interrupt trigger from userland.
<How to use>
- Read current setting
# cat /sys/class/tty/ttyS0/rx_trig_bytes
8
- Write user setting
# echo 1 > /sys/class/tty/ttyS0/rx_trig_bytes
# cat /sys/class/tty/ttyS0/rx_trig_bytes
1
<Support uart devices>
- 16550A and Tegra (1, 4, 8, or 14 bytes)
- 16650V2 (8, 16, 24, or 28 bytes)
- 16654 (8, 16, 56, or 60 bytes)
- 16750 (1, 16, 32, or 56 bytes)
<Change log>
Changes in V9:
- Use attr_group instead of dev_spec_attr_group of uart_port structure
Changes in V8:
- Divide this patch from V7's patch based on Greg's comment
Changes in V7:
- Add Documentation
- Change I/F name from rx_int_trig to rx_trig_bytes because the name
rx_int_trig is hard to understand how users specify the value
Changes in V6:
- Move FCR_RX_TRIG_* definition in 8250.h to include/uapi/linux/serial_reg.h,
rename those to UART_FCR_R_TRIG_*, and use UART_FCR_TRIGGER_MASK to
UART_FCR_R_TRIG_BITS()
- Change following function names:
convert_fcr2val() => fcr_get_rxtrig_bytes()
convert_val2rxtrig() => bytes_to_fcr_rxtrig()
- Fix typo in serial8250_do_set_termios()
- Delete the verbose error message pr_info() in bytes_to_fcr_rxtrig()
- Rename *rx_int_trig/rx_trig* to *rxtrig* for several functions or variables
(but UI remains rx_int_trig)
- Change the meaningless variable name 'val' to 'bytes' following functions:
fcr_get_rxtrig_bytes(), bytes_to_fcr_rxtrig(), do_set_rxtrig(),
do_serial8250_set_rxtrig(), and serial8250_set_attr_rxtrig()
- Use up->fcr in order to get rxtrig_bytes instead of rx_trig_raw in
fcr_get_rxtrig_bytes()
- Use conf_type->rxtrig_bytes[0] instead of switch statement for support check
in register_dev_spec_attr_grp()
- Delete the checking whether a user changed FCR or not when minimum buffer
is needed in serial8250_do_set_termios()
Changes in V5.1:
- Fix FCR_RX_TRIG_MAX_STATE definition
Changes in V5:
- Support Tegra, 16650V2, 16654, and 16750
- Store default FCR value to up->fcr when the port is first created
- Add rx_trig_byte[] in uart_config[] for each device and use rx_trig_byte[]
in convert_fcr2val() and convert_val2rxtrig()
Changes in V4:
- Introduce fifo_bug flag in uart_8250_port structure
This is enabled only when parity is enabled and UART_BUG_PARITY is enabled
for up->bugs. If this flag is enabled, user cannot set RX trigger.
- Return -EOPNOTSUPP when it does not support device at convert_fcr2val() and
at convert_val2rxtrig()
- Set the nearest lower RX trigger when users input a meaningless value at
convert_val2rxtrig()
- Check whether p->fcr is existing at serial8250_clear_and_reinit_fifos()
- Set fcr = up->fcr in the begging of serial8250_do_set_termios()
Changes in V3:
- Change I/F from ioctl(2) to sysfs(rx_int_trig)
Changed in V2:
- Use _IOW for TIOCSFIFORTRIG definition
- Pass the interrupt trigger value itself
Signed-off-by: Yoshihiro YUNOMAE <yoshihiro.yunomae.ez@hitachi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It helps to cast struct uart_port to struct uart_8250_port at runtime.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add support for dmaengine API. The drivers can implement the
struct uart_8250_dma member in struct uart_8250_port and
8250.c can take care of the rest.
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Allows overriding default methods serial_in/serial_out.
In such platform specific replacement it is possible to use
other regshift, biased register offset, any other manipulation
that is not covered with common default methods.
Overriding default methods may be useful for platforms which got
serial peripheral with registers represented in big endian.
In this situation and assuming that 32 bit operations / alignment
is required then it may be useful to swab words before/after
accessing the serial registers.
Signed-off-by: Noam Camus <noamc@ezchip.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This resolves the differences between the original 8250 patch, the revised 8250 patch
and the independant clean up of the octeon driver (to use platform devices properly yay!)
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The old interface just copies bits over and calls the newer one.
In addition we can now pass more information.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull the MCA deletion branch from Paul Gortmaker:
"It was good that we could support MCA machines back in the day, but
realistically, nobody is using them anymore. They were mostly limited
to 386-sx 16MHz CPU and some 486 class machines and never more than
64MB of RAM. Even the enthusiast hobbyist community seems to have
dried up close to ten years ago, based on what you can find searching
various websites dedicated to the relatively short lived hardware.
So lets remove the support relating to CONFIG_MCA. There is no point
carrying this forward, wasting cycles doing routine maintenance on it;
wasting allyesconfig build time on validating it, wasting I/O on git
grep'ping over it, and so on."
Let's see if anybody screams. It generally has compiled, and James
Bottomley pointed out that there was a MCA extension from NCR that
allowed for up to 4GB of memory and PPro-class machines. So in *theory*
there may be users out there.
But even James (technically listed as a maintainer) doesn't actually
have a system, and while Alan Cox claims to have a machine in his cellar
that he offered to anybody who wants to take it off his hands, he didn't
argue for keeping MCA support either.
So we could bring it back. But somebody had better speak up and talk
about how they have actually been using said MCA hardware with modern
kernels for us to do that. And David already took the patch to delete
all the networking driver code (commit a5e371f61ad3: "drivers/net:
delete all code/drivers depending on CONFIG_MCA").
* 'delete-mca' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
MCA: delete all remaining traces of microchannel bus support.
scsi: delete the MCA specific drivers and driver code
serial: delete the MCA specific 8250 support.
arm: remove ability to select CONFIG_MCA
The support for CONFIG_MCA is being removed, since the 20
year old hardware simply isn't capable of meeting today's
software demands on CPU and memory resources.
This commit removes the MCA specific 8250 UART code.
Cc: Alan Cox <alan@linux.intel.com>
Cc: linux-serial@vger.kernel.org
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Introduce yet another 8250 registration function.
This time it is serial8250_register_8250_port() and it
allows us to register 8250 hardware instances using struct
uart_8250_port. The new function makes it possible to
register 8250 hardware that makes use of 8250 specific
callbacks such as ->dl_read() and ->dl_write().
Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The "KT" serial port has another use case for a "received break" quirk,
so before adding another special case to the 8250 core take this
opportunity to push such quirks out of the core and into a uart_port op.
Stephen says:
"If the callback function is to no longer live in 8250.c itself,
arch/arm/mach-tegra/devices.c isn't logically a good place to put it,
and that file will be going away once we get rid of all the board files
and move solely to device tree."
...so since 8250_pci.c houses all the quirks for pci serial devices this
quirk is similarly housed in of_serial.c. Once the open firmware
conversion completes the infrastructure details
(include/linux/of_serial.h, and the export) can all be removed to make
this self contained to of_serial.c.
Cc: Nhan H Mai <nhan.h.mai@intel.com>
Cc: Colin Cross <ccross@android.com>
Cc: Olof Johansson <olof@lixom.net>
[stephen: kill CONFIG_SERIAL_TEGRA in favor just using CONFIG_ARCH_TEGRA]
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sudhakar Mamillapalli <sudhakar@fb.com>
Reported-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Sending a break on the SOC UARTs found in some MPC83xx/85xx/86xx
chips seems to cause a short lived IRQ storm (/proc/interrupts
typically shows somewhere between 300 and 1500 events). Unfortunately
this renders SysRQ over the serial console completely inoperable.
The suggested workaround in the errata is to read the Rx register,
wait one character period, and then read the Rx register again.
We achieve this by tracking the old LSR value, and on the subsequent
interrupt event after a break, we don't read LSR, instead we just
read the RBR again and return immediately.
The "fsl,ns16550" is used in the compatible field of the serial
device to mark UARTs known to have this issue.
Thanks to Scott Wood for providing the errata data which led to
a much cleaner fix.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
For drivers that need to construct their own IRQ handler, the
three components are seen in the current handle_port -- i.e.
Rx, Tx and modem_status.
Make these exported symbols so that "almost" 8250 UARTs can
construct their own IRQ handler with these shared components,
while working around their own unique errata issues.
The function names are given a serial8250 prefix, since they
are now entering the global namespace.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This reverts commit 6b1a98d1c4.
It causes a build error that needs to be resolved differently.
Cc: Alan Cox <alan@linux.intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The Synopsys DesignWare 8250 is an 8250 that has an extra interrupt that
gets raised when writing to the LCR when busy. To handle this we need
special serial_out, serial_in and handle_irq methods. Add a new
function serial8250_use_designware_io() that configures a uart_port with
these accessors.
Cc: Alan Cox <alan@linux.intel.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Some ports (e.g. Synopsys DesignWare 8250) have special requirements for
handling the interrupts. Allow these platforms to specify their own
interrupt handler that will override the default.
serial8250_handle_irq() is provided so that platforms can extend the IRQ
handler rather than completely replacing it.
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Not every platform that has generic legacy 8250 ports manages to have them
clocked the right way or without errata. Provide a generic interface to
allow platforms to override the default behaviour in a manner that dumps
the complexity in *their* code not the 8250 driver.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Dirk Brandewie <dirk.brandewie@gmail.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Lukas Wunner