The 8250 handle_irq callback is not just called from the interrupt
handler but also from a timer callback when polling (e.g. for ports
without an interrupt line). Consequently the callback must explicitly
disable interrupts to avoid a potential deadlock with another interrupt
in polled mode.
Add back an irqrestore-version of the sysrq port-unlock helper and use
it in the 8250 callbacks that need it.
Fixes: 75f4e830fa ("serial: do not restore interrupt state in sysrq helper")
Cc: stable@vger.kernel.org # 5.13
Cc: Joel Stanley <joel@jms.id.au>
Cc: Andrew Jeffery <andrew@aj.id.au>
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210714080427.28164-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Aspeed Virtual UARTs directly bridge e.g. the system console UART on the
LPC bus to the UART interface on the BMC's internal APB. As such there's
no RS-232 signalling involved - the UART interfaces on each bus are
directly connected as the producers and consumers of the one set of
FIFOs.
The APB in the AST2600 generally runs at 100MHz while the LPC bus peaks
at 33MHz. The difference in clock speeds exposes a race in the VUART
design where a Tx data burst on the APB interface can result in a byte
lost on the LPC interface. The symptom is LSR[DR] remains clear on the
LPC interface despite data being present in its Rx FIFO, while LSR[THRE]
remains clear on the APB interface as the host has not consumed the data
the BMC has transmitted. In this state, the UART has stalled and no
further data can be transmitted without manual intervention (e.g.
resetting the FIFOs, resulting in loss of data).
The recommended work-around is to insert a read cycle on the APB
interface between writes to THR.
Cc: ChiaWei Wang <chiawei_wang@aspeedtech.com>
Tested-by: ChiaWei Wang <chiawei_wang@aspeedtech.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210520021334.497341-2-andrew@aj.id.au
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty_buffer_space_avail returns values >= 0, so make it clear by the
return type.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210505091928.22010-25-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Previously this driver's use of devm_ioremap_resource() led to
duplicated calls to __release_region() when unbinding it (one from
serial8250_release_std_resource() and one from devres_release_all()),
the second of which resulted in a warning message:
# echo 1e787000.serial > /sys/bus/platform/drivers/aspeed-vuart/unbind
[33091.774200] Trying to free nonexistent resource <000000001e787000-000000001e78703f>
With this change the driver uses the generic serial8250 code's
UPF_IOREMAP to take care of the register mapping automatically instead
of doing its own devm_ioremap_resource(), thus avoiding the duplicate
__release_region() on unbind.
In doing this we eliminate vuart->regs, since it merely duplicates
vuart->port->port.membase, which we now use for our I/O accesses.
Reported-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210510014231.647-4-zev@bewilderbeest.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Previously this had only been initialized if we hit the throttling path
in aspeed_vuart_handle_irq(); moving it to the probe function is a
slight consistency improvement and avoids redundant reinitialization in
the interrupt handler. It also serves as preparation for converting the
driver's I/O accesses to use port->port.membase instead of its own
vuart->regs.
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210510014231.647-3-zev@bewilderbeest.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is a small prepatory step for changing the way this driver does
its I/O accesses.
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210510014231.647-2-zev@bewilderbeest.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The uart_unlock_and_check_sysrq() helper can be used to defer processing
of sysrq until the interrupt handler has released the port lock and is
about to return.
Since commit 81e2073c17 ("genirq: Disable interrupts for force
threaded handlers") interrupt handlers that are not explicitly requested
as threaded are always called with interrupts disabled and there is no
need to save the interrupt state when taking the port lock.
Instead of adding another sysrq helper for when the interrupt state has
not needlessly been saved, drop the state parameter from
uart_unlock_and_check_sysrq() and update its callers to no longer
explicitly disable interrupts in their interrupt handlers.
Cc: Joel Stanley <joel@jms.id.au>
Cc: Andrew Jeffery <andrew@aj.id.au>
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210416140557.25177-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
These allow describing all the Aspeed VUART attributes currently
available via sysfs. aspeed,lpc-interrupts provides a replacement for
the deprecated aspeed,sirq-polarity-sense property.
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210412034712.16778-4-zev@bewilderbeest.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This splits dedicated aspeed_vuart_set_{sirq,lpc_address}() functions
out of the sysfs store functions in preparation for adding DT
properties that will be poking the same registers. While we're at it,
these functions now provide some basic bounds-checking on their
arguments.
Reviewed-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210412034712.16778-3-zev@bewilderbeest.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit 54e53b2e80
("tty: serial: 8250: pass IRQ shared flag to UART ports")
nicely explained the problem:
---8<---8<---
On some systems IRQ lines between multiple UARTs might be shared. If so, the
irqflags have to be configured accordingly. The reason is: The 8250 port startup
code performs IRQ tests *before* the IRQ handler for that particular port is
registered. This is performed in serial8250_do_startup(). This function checks
whether IRQF_SHARED is configured and only then disables the IRQ line while
testing.
This test is performed upon each open() of the UART device. Imagine two UARTs
share the same IRQ line: On is already opened and the IRQ is active. When the
second UART is opened, the IRQ line has to be disabled while performing IRQ
tests. Otherwise an IRQ might handler might be invoked, but the IRQ itself
cannot be handled, because the corresponding handler isn't registered,
yet. That's because the 8250 code uses a chain-handler and invokes the
corresponding port's IRQ handling routines himself.
Unfortunately this IRQF_SHARED flag isn't configured for UARTs probed via device
tree even if the IRQs are shared. This way, the actual and shared IRQ line isn't
disabled while performing tests and the kernel correctly detects a spurious
IRQ. So, adding this flag to the DT probe solves the issue.
Note: The UPF_SHARE_IRQ flag is configured unconditionally. Therefore, the
IRQF_SHARED flag can be set unconditionally as well.
Example stack trace by performing `echo 1 > /dev/ttyS2` on a non-patched system:
|irq 85: nobody cared (try booting with the "irqpoll" option)
| [...]
|handlers:
|[<ffff0000080fc628>] irq_default_primary_handler threaded [<ffff00000855fbb8>] serial8250_interrupt
|Disabling IRQ #85
---8<---8<---
But unfortunately didn't fix the root cause. Let's try again here by moving
IRQ flag assignment from serial_link_irq_chain() to serial8250_do_startup().
This should fix the similar issue reported for 8250_pnp case.
Since this change we don't need to have custom solutions in 8250_aspeed_vuart
and 8250_of drivers, thus, drop them.
Fixes: 1c2f04937b ("serial: 8250: add IRQ trigger support")
Reported-by: Li RongQing <lirongqing@baidu.com>
Cc: Kurt Kanzenbach <kurt@linutronix.de>
Cc: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Acked-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20200211135559.85960-1-andriy.shevchenko@linux.intel.com
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.
Cc: Joel Stanley <joel@jms.id.au>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-aspeed@lists.ozlabs.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Acked-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/20191213000657.931618-5-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Make the SIRQ polarity for Aspeed AST24xx/25xx VUART configurable via
sysfs. This setting need to be changed on specific host platforms
depending on the selected host interface (LPC / eSPI).
The setting is configurable via sysfs rather than device-tree to stay in
line with other related configurable settings.
On AST2500 the VUART SIRQ polarity can be auto-configured by reading a
bit from a configuration register, e.g. the LPC/eSPI interface
configuration bit.
Tested: Verified on TYAN S7106 mainboard.
Signed-off-by: Oskar Senft <osk@google.com>
Link: https://lore.kernel.org/r/20190905144130.220713-1-osk@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Let's take advantage of the new ("serial: core: Allow processing sysrq
at port unlock time") to handle sysrqs more cleanly.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The "unthrottle_timeout" is HZ/10 but mod_timer() takes a the actual
jiffie where you want it to timeout, not an offset.
Fixes: 5909c0bf9c ("serial/aspeed-vuart: Implement quick throttle mechanism")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Although we populate the ->throttle and ->unthrottle UART operations,
these may not be called until the ldisc has had a chance to schedule and
check buffer space. This means that we may overflow the flip buffers
without ever hitting the ldisc's throttle threshold.
This change implements an interrupt-based throttle, where we check for
space in the flip buffers before reading characters from the UART's
FIFO. If there's no space available, we disable the RX interrupt and
schedule a timer to check for space later.
For this, we need an unlocked version of the set_throttle function to be
able to change throttle state from the irq_handler, which already holds
port->lock.
This prevents a case where we drop characters under heavy RX load.
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>
The aspeed VUART runs at LPC bus frequency, rather than being restricted
to a typical UART baud rate. This means that the VUART can receive a lot
of data, which can overrun tty flip buffers, and/or cause a large amount
of interrupt traffic.
This change implements the uart_port->throttle & unthrottle callbacks,
implemented by disabling the receiver line status & received data
available IRQs.
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>
Now that the SPDX tag is in all tty files, that identifies the license
in a specific and legally-defined manner. So the extra GPL text wording
can be removed as it is no longer needed at all.
This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text. And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.
No copyright headers or other non-license-description text was removed.
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Joachim Eastwood <manabian@gmail.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: Pat Gefre <pfg@sgi.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: Sylvain Lemieux <slemieux.tyco@gmail.com>
Cc: Carlo Caione <carlo@caione.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Andy Gross <andy.gross@linaro.org>
Cc: David Brown <david.brown@linaro.org>
Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Timur Tabi <timur@tabi.org>
Cc: Tony Prisk <linux@prisktech.co.nz>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: "Sören Brinkmann" <soren.brinkmann@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.
Update the drivers/tty files files with the correct SPDX license
identifier based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of
the full boiler plate text.
This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: David Sterba <dsterba@suse.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Joachim Eastwood <manabian@gmail.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Richard Genoud <richard.genoud@gmail.com>
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: "Maciej W. Rozycki" <macro@linux-mips.org>
Cc: "Uwe Kleine-König" <kernel@pengutronix.de>
Cc: Pat Gefre <pfg@sgi.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: Sylvain Lemieux <slemieux.tyco@gmail.com>
Cc: Carlo Caione <carlo@caione.org>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Andy Gross <andy.gross@linaro.org>
Cc: David Brown <david.brown@linaro.org>
Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: Laxman Dewangan <ldewangan@nvidia.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Jonathan Hunter <jonathanh@nvidia.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Patrice Chotard <patrice.chotard@st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Peter Korsgaard <jacmet@sunsite.dk>
Cc: Timur Tabi <timur@tabi.org>
Cc: Tony Prisk <linux@prisktech.co.nz>
Cc: Michal Simek <michal.simek@xilinx.com>
Cc: "Sören Brinkmann" <soren.brinkmann@xilinx.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Jiri Slaby <jslaby@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are several error handling paths in aspeed_vuart_probe(),
where sysfs group is left unremoved. The patch fixes them.
Found by Linux Driver Verification project (linuxtesting.org).
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This change adds a driver for the 16550-based Aspeed virtual UART
device. We use a similar process to the of_serial driver for device
probe, but expose some VUART-specific functions through sysfs too.
The VUART is two UART 'front ends' connected by their FIFO (no actual
serial line in between). One is on the BMC side (management controller)
and one is on the host CPU side.
This driver is for the BMC side. The sysfs files allow the BMC
userspace, which owns the system configuration policy, to specify at
what IO port and interrupt number the host side will appear to the host
on the Host <-> BMC LPC bus. It could be different on a different system
(though most of them use 3f8/4).
OpenPOWER host firmware doesn't like it when the host-side of the
VUART's FIFO is not drained. This driver only disables host TX discard
mode when the port is in use. We set the VUART enabled bit when we bind
to the device, and clear it on unbind.
We don't want to do this on open/release, as the host may be using this
bit to configure serial output modes, which is independent of whether
the devices has been opened by BMC userspace.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
