The default polarity of RS485 DE signal is active high. This driver does
not handle such case properly. Currently, when a pin is multiplexed as a
UART CTS_B on boot, this pin is pulled HIGH by the i.MX UART CTS circuit,
which activates DE signal on the RS485 transceiver and thus behave as if
the RS485 was transmitting data, so the system blocks the RS485 bus when
it starts and until user application takes over. This behavior is not OK.
The problem consists of two separate parts.
First, the i.MX UART IP requires UCR1 UARTEN and UCR2 RXEN to be set for
UCR2 CTSC and CTS bits to have any effect. The UCR2 CTSC bit permits the
driver to set CTS (RTS_B or RS485 DE signal) to either level sychronous
to the internal UART IP clock. Compared to other options, like GPIO CTS
control, this has the benefit of being synchronous to the UART IP clock
and thus without glitches or bus delays. The reason for the CTS design
is likely because when the Receiver is disabled, the UART IP can never
indicate that it is ready to receive data by assering CTS signal, so
the CTS is always pulled HIGH by default.
When the port is closed by user space, imx_uart_stop_rx() clears UCR2
RXEN bit, and imx_uart_shutdown() clears UCR1 UARTEN bit. This disables
UART Receiver and UART itself, and forces CTS signal HIGH, which leads
to the RS485 bus being blocked because RS485 DE is incorrectly active.
The proposed solution for this problem is to keep the Receiver running
even after the port is closed, but in loopback mode. This disconnects
the RX FIFO input from the RXD external signal, and since UCR2 TXEN is
cleared, the UART Transmitter is disabled, so nothing can feed data in
the RX FIFO. Because the Receiver is still enabled, the UCR2 CTSC and
CTS bits still have effect and the CTS (RS485 DE) control is retained.
Note that in case of RS485 DE signal active low, there is no problem and
no special handling is necessary. The CTS signal defaults to HIGH, thus
the RS485 is by default set to Receive and the bus is not blocked.
Note that while there is the possibility to control CTS using GPIO with
either CTS polarity, this has the downside of not being synchronous to
the UART IP clock and thus glitchy and susceptible to slow DE switching.
Second, on boot, before the UART driver probe callback is called, the
driver core triggers pinctrl_init_done() and configures the IOMUXC to
default state. At this point, UCR1 UARTEN and UCR2 RXEN are both still
cleared, but UART CTS_B (RS485 DE) is configured as CTS function, thus
the RTS signal is pulled HIGH by the UART IP CTS circuit.
One part of the solution here is to enable UCR1 UARTEN and UCR2 RXEN and
UTS loopback in this driver probe callback, thus unblocking the CTSC and
CTS control early on. But this is still too late, since the pin control
is already configured and CTS has been pulled HIGH for a short period
of time.
When Linux kernel boots and this driver is bound, the pin control is set
to special "init" state if the state is available, and driver can switch
the "default" state afterward when ready. This state can be used to set
the CTS line as a GPIO in DT temporarily, and a GPIO hog can force such
GPIO to LOW, thus keeping the RS485 DE line LOW early on boot. Once the
driver takes over and UCR1 UARTEN and UCR2 RXEN and UTS loopback are all
enabled, the driver can switch to "default" pin control state and control
the CTS line as function instead. DT binding example is below:
"
&gpio6 {
rts-init-hog {
gpio-hog;
gpios = <5 0>;
output-low;
line-name = "rs485-de";
};
};
&uart5 { /* DHCOM UART2 */
pinctrl-0 = <&pinctrl_uart5>;
pinctrl-1 = <&pinctrl_uart5_init>;
pinctrl-names = "default", "init";
...
};
pinctrl_uart5_init: uart5-init-grp {
fsl,pins = <
...
MX6QDL_PAD_CSI0_DAT19__GPIO6_IO05 0x30b1
>;
};
pinctrl_uart5: uart5-grp {
fsl,pins = <
...
MX6QDL_PAD_CSI0_DAT19__UART5_CTS_B 0x30b1
>;
};
"
Tested-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20220929144400.13571-1-marex@denx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Take advantage of the new uart_xmit_advance() helper.
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-18-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When a UART port is newly registered, uart_configure_port() seeks to
deassert RS485 Transmit Enable by setting the RTS bit in port->mctrl.
However a number of UART drivers interpret a set RTS bit as *assertion*
instead of deassertion: Affected drivers include those using
serial8250_em485_config() (except 8250_bcm2835aux.c) and some using
mctrl_gpio (e.g. imx.c).
Since the interpretation of the RTS bit is driver-specific, it is not
suitable as a means to centrally deassert Transmit Enable in the serial
core. Instead, the serial core must call on drivers to deassert it in
their driver-specific way. One way to achieve that is to call
->rs485_config(). It implicitly deasserts Transmit Enable.
So amend uart_configure_port() and uart_resume_port() to invoke
uart_rs485_config(). That allows removing calls to uart_rs485_config()
from drivers' ->probe() hooks and declaring the function static.
Skip any invocation of ->set_mctrl() if RS485 is enabled. RS485 has no
hardware flow control, so the modem control lines are irrelevant and
need not be touched. When leaving RS485 mode, reset the modem control
lines to the state stored in port->mctrl. That way, UARTs which are
muxed between RS485 and RS232 transceivers drive the lines correctly
when switched to RS232. (serial8250_do_startup() historically raises
the OUT1 modem signal because otherwise interrupts are not signaled on
ancient PC UARTs, but I believe that no longer applies to modern,
RS485-capable UARTs and is thus safe to be skipped.)
imx.c modifies port->mctrl whenever Transmit Enable is asserted and
deasserted. Stop it from doing that so port->mctrl reflects the RS232
line state.
8250_omap.c deasserts Transmit Enable on ->runtime_resume() by calling
->set_mctrl(). Because that is now a no-op in RS485 mode, amend the
function to call serial8250_em485_stop_tx().
fsl_lpuart.c retrieves and applies the RS485 device tree properties
after registering the UART port. Because applying now happens on
registration in uart_configure_port(), move retrieval of the properties
ahead of uart_add_one_port().
Link: https://lore.kernel.org/all/20220329085050.311408-1-matthias.schiffer@ew.tq-group.com/
Link: https://lore.kernel.org/all/8f538a8903795f22f9acc94a9a31b03c9c4ccacb.camel@ginzinger.com/
Fixes: d3b3404df3 ("serial: Fix incorrect rs485 polarity on uart open")
Cc: stable@vger.kernel.org # v4.14+
Reported-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reported-by: Roosen Henri <Henri.Roosen@ginzinger.com>
Tested-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/2de36eba3fbe11278d5002e4e501afe0ceaca039.1663863805.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There should be no reason to adjust old ktermios which is going to get
discarded anyway.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Embed rs485_supported to uart_port to allow serial core to tweak it as
needed.
Reviewed-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220704094515.6831-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To be able to alter ADDRB within ->rs485_config(), take termios_rwsem
before calling ->rs485_config() and pass termios.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624204210.11112-5-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The driver provides different rs485_supported for the case where RTS is
not available making it unnecessary to handle it in
imx_uart_rs485_config.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-32-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add information on supported serial_rs485 features.
In the case where RTS is lacking, RS485 cannot be enabled so provide
zero rs485_supported for that case. Perhaps it would make sense to not
provide rs485_config() at all in that case but such a change would have
userspace visible impact/change in behavior so this patch does not
attempt it.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-17-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A few serial drivers make a call to rs485_config() themselves (all
these seem to relate to init). Convert them all to use a common helper
which makes it easy to make adjustments on tasks related to it as
serial_rs485 struct sanitization is going to be added.
In pci_fintek_setup() (in 8250_pci.c), the rs485_config() call was made
with NULL, however, it can be changed to pass uart_port's rs485 struct.
No other callers should pass NULL into rs485_config() so the NULL check
can now be eliminated.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here is the big set of tty and serial driver updates for 5.19-rc1.
Lots of tiny cleanups in here, the major stuff is:
- termbit cleanups and unification by Ilpo. A much needed
change that goes a long way to making things simpler for all
of the different arches
- tty documentation cleanups and movements to their own place in
the documentation tree
- old tty driver cleanups and fixes from Jiri to bring some
existing drivers into the modern world
- RS485 cleanups and unifications to make it easier for
individual drivers to support this mode instead of having to
duplicate logic in each driver
- Lots of 8250 driver updates and additions
- new device id additions
- n_gsm continued fixes and cleanups
- other minor serial driver updates and cleanups
All of these have been in linux-next for weeks with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty and serial driver updates from Greg KH:
"Here is the big set of tty and serial driver updates for 5.19-rc1.
Lots of tiny cleanups in here, the major stuff is:
- termbit cleanups and unification by Ilpo. A much needed change that
goes a long way to making things simpler for all of the different
arches
- tty documentation cleanups and movements to their own place in the
documentation tree
- old tty driver cleanups and fixes from Jiri to bring some existing
drivers into the modern world
- RS485 cleanups and unifications to make it easier for individual
drivers to support this mode instead of having to duplicate logic
in each driver
- Lots of 8250 driver updates and additions
- new device id additions
- n_gsm continued fixes and cleanups
- other minor serial driver updates and cleanups
All of these have been in linux-next for weeks with no reported issues"
* tag 'tty-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (166 commits)
tty: Rework receive flow control char logic
pcmcia: synclink_cs: Don't allow CS5-6
serial: stm32-usart: Correct CSIZE, bits, and parity
serial: st-asc: Sanitize CSIZE and correct PARENB for CS7
serial: sifive: Sanitize CSIZE and c_iflag
serial: sh-sci: Don't allow CS5-6
serial: txx9: Don't allow CS5-6
serial: rda-uart: Don't allow CS5-6
serial: digicolor-usart: Don't allow CS5-6
serial: uartlite: Fix BRKINT clearing
serial: cpm_uart: Fix build error without CONFIG_SERIAL_CPM_CONSOLE
serial: core: Do stop_rx in suspend path for console if console_suspend is disabled
tty: serial: qcom-geni-serial: Remove uart frequency table. Instead, find suitable frequency with call to clk_round_rate.
dt-bindings: serial: renesas,em-uart: Add RZ/V2M clock to access the registers
serial: 8250_fintek: Check SER_RS485_RTS_* only with RS485
Revert "serial: 8250_mtk: Make sure to select the right FEATURE_SEL"
serial: msm_serial: disable interrupts in __msm_console_write()
serial: meson: acquire port->lock in startup()
serial: 8250_dw: Use dev_err_probe()
serial: 8250_dw: Use devm_add_action_or_reset()
...
Not much dramatic changes at this time, but we've received quite
a lot of changes for ASoC, while there are still a few fixes and
quirks for usual HD- and USB-auido. Here are some highlights.
* ASoC:
- Overhaul of endianness specification for data formats, avoiding
needless restrictions due to CODECs
- Initial stages of Intel AVS driver merge
- Introduction of v4 IPC mechanism for SOF
- TDM mode support for AK4613
- Support for Analog Devices ADAU1361, Cirrus Logic CS35L45, Maxim
MAX98396, MediaTek MT8186, NXP i.MX8 micfil and SAI interfaces,
nVidia Tegra186 ASRC, and Texas Instruments TAS2764 and TAS2780
* Others
- A few regression fixes after the USB-audio endpoint management
refactoring
- More enhancements for Cirrus HD-audio codec support (still ongoing)
- Addition of generic serial MIDI driver
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Merge tag 'sound-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
Pull sound updates from Takashi Iwai:
"Not much dramatic changes at this time, but we've received quite a lot
of changes for ASoC, while there are still a few fixes and quirks for
usual HD- and USB-auido. Here are some highlights.
ASoC:
- Overhaul of endianness specification for data formats, avoiding
needless restrictions due to CODECs
- Initial stages of Intel AVS driver merge
- Introduction of v4 IPC mechanism for SOF
- TDM mode support for AK4613
- Support for Analog Devices ADAU1361, Cirrus Logic CS35L45, Maxim
MAX98396, MediaTek MT8186, NXP i.MX8 micfil and SAI interfaces,
nVidia Tegra186 ASRC, and Texas Instruments TAS2764 and TAS2780
Others:
- A few regression fixes after the USB-audio endpoint management
refactoring
- More enhancements for Cirrus HD-audio codec support (still ongoing)
- Addition of generic serial MIDI driver"
* tag 'sound-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (504 commits)
ALSA: hda/realtek - Add new type for ALC245
ALSA: usb-audio: Configure sync endpoints before data
ALSA: ctxfi: fix typo in comment
ALSA: cs5535audio: fix typo in comment
ALSA: ctxfi: Add SB046x PCI ID
ALSA: usb-audio: Add missing ep_idx in fixed EP quirks
ALSA: usb-audio: Workaround for clock setup on TEAC devices
ALSA: lola: Bounds check loop iterator against streams array size
ASoC: max98090: Move check for invalid values before casting in max98090_put_enab_tlv()
ASoC: rt1308-sdw: add the default value of register 0xc320
ASoC: rt9120: Use pm_runtime and regcache to optimize 'pwdnn' logic
ASoC: rt9120: Fix 3byte read, valule offset typo
ASoC: amd: acp: Set Speaker enable/disable pin through rt1019 codec driver.
ASoC: amd: acp: Set Speaker enable/disable pin through rt1019 codec driver
ASoC: wm2000: fix missing clk_disable_unprepare() on error in wm2000_anc_transition()
ASoC: codecs: lpass: Fix passing zero to 'PTR_ERR'
ASoC: SOF: sof-client-ipc-flood-test: use pm_runtime_resume_and_get()
ASoC: SOF: mediatek: remove duplicate include in mt8195.c
ASoC: SOF: mediatek: Add mt8195 debug dump
ASoC: SOF: mediatek: Add mediatek common debug dump
...
The i.MX DMA drivers are device tree only, nothing in
include/linux/platform_data/dma-imx.h has platform_data in it, so move
the file to include/linux/dma/imx-dma.h.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-By: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20220414162249.3934543-10-s.hauer@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Commit 76821e222c ("serial: imx: ensure that RX irqs are off if RX is
off") accidentally enabled overrun interrupts unconditionally when
deferring DMA enable until after the receiver has been enabled during
startup.
Fix this by using the DMA-initialised instead of DMA-enabled flag to
determine whether overrun interrupts should be enabled.
Note that overrun interrupts are already accounted for in
imx_uart_clear_rx_errors() when using DMA since commit 41d98b5da9
("serial: imx-serial - update RX error counters when DMA is used").
Fixes: 76821e222c ("serial: imx: ensure that RX irqs are off if RX is off")
Cc: stable@vger.kernel.org # 4.17
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20220411081957.7846-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In uart_set_rs485_config() the serial core already assigns the passed
serial_rs485 struct to the uart port.
So remove the assignment in the drivers rs485_config() function to avoid
reduncancy.
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-8-LinoSanfilippo@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently, uart_console_write->putchar's second parameter (the
character) is of type int. It makes little sense, provided uart_console_write()
accepts the input string as "const char *s" and passes its content -- the
characters -- to putchar(). So switch the character's type to unsigned
char.
We don't use char as that is signed on some platforms. That would cause
troubles for drivers which (implicitly) cast the char to u16 when
writing to the device. Sign extension would happen in that case and the
value written would be completely different to the provided char. DZ is
an example of such a driver -- on MIPS, it uses u16 for dz_out in
dz_console_putchar().
Note we do the char -> uchar conversion implicitly in
uart_console_write(). Provided we do not change size of the data type,
sign extension does not happen there, so the problem is void.
This makes the types consistent and unified with the rest of the uart
layer, which uses unsigned char in most places already. One exception is
xmit_buf, but that is going to be converted later.
Cc: Paul Cercueil <paul@crapouillou.net>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Ludovic Desroches <ludovic.desroches@microchip.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Baruch Siach <baruch@tkos.co.il>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: Karol Gugala <kgugala@antmicro.com>
Cc: Mateusz Holenko <mholenko@antmicro.com>
Cc: Vladimir Zapolskiy <vz@mleia.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Kevin Hilman <khilman@baylibre.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: Taichi Sugaya <sugaya.taichi@socionext.com>
Cc: Takao Orito <orito.takao@socionext.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: "Andreas Färber" <afaerber@suse.de>
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Baolin Wang <baolin.wang7@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Peter Korsgaard <peter@korsgaard.com>
Cc: Michal Simek <michal.simek@xilinx.com>
Acked-by: Richard Genoud <richard.genoud@gmail.com> [atmel_serial]
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Neil Armstrong <narmstrong@baylibre.com> # meson_serial
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220303080831.21783-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Right now, even when `delay_rts_before_send` and `delay_rts_after_send`
are 0, the hrtimer is triggered (with timeout 0) which can introduce a
few 100us of additional overhead on slower i.MX platforms.
Implement a fast path when the delays are 0, where the RTS signal is
toggled immediately instead of going through an hrtimer. This fast path
behaves identical to the code before delay support was implemented.
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Harald Seiler <hws@denx.de>
Link: https://lore.kernel.org/r/20220119145204.238767-1-hws@denx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Triggering RX interrupt for every byte defeats the purpose of aging
timer and leads to interrupt storm at high baud rates. The interrupt
storm can starve line discipline worker and prevent tty throttling,
rendering hardware/software flow control useless.
Increase receiver trigger level to 8 to increase the minimum period
between RX interrupts to 8 characters time. The tradeoff is increased
latency.
Aging timer resets with every received character. Worst case scenario
happens when RX data intercharacter delay is slightly less than the
aging timer timeout (8 characters time). The upper bound of the time
a character can wait in RxFIFO before interrupt is raised is:
(RXTL - 1) * (8 character time timeout + received 1 character time)
Usually the data is received in frames, with low intercharacter delay.
In such case the latency increase is 8 characters time at the end of
the frame with probability (RXTL - 1) / RXTL.
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Tomasz Moń <tomasz.mon@camlingroup.com>
Link: https://lore.kernel.org/r/20220117060417.624613-1-tomasz.mon@camlingroup.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The UCR4_OREN should be disabled before disabling the uart receiver in
.stop_rx() instead of in the .shutdown().
Otherwise, if we have the overrun error during the receiver disable
process, the overrun interrupt will keep trigging until we disable the
OREN interrupt in the .shutdown(), because the ORE status can only be
cleared when read the rx FIFO or reset the controller. Although the
called time between the receiver disable and OREN disable in .shutdown()
is very short, there is still the risk of endless interrupt during this
short period of time. So here change to disable OREN before the receiver
been disabled in .stop_rx().
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20211125020349.4980-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Clear RTSD status before enabling the irq event for RTSD in
imx_uart_enable_wakeup function.
Since RTSD can be set as the wakeup source, this can avoid any risk of
false triggering of a wake-up interrupts.
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20211125014306.4432-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
During console setup imx_uart_console_setup() enables clocks, but they
are never disabled when the console is unregistered, this leads to
clk_prepare_enable() being called multiple times without a matching
clk_disable_unprepare() in case of console unregister.
Ensure that clock enable/disable are balanced adding
clk_disable_unprepare() in the console exit callback.
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Link: https://lore.kernel.org/r/20211020192643.476895-3-francesco.dolcini@toradex.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In order to optimize serial communication (performance/throughput VS
latency), we may need to tweak DMA period number and size. This adds
DT properties to configure those values before initialising DMA.
The defaults will stay the same as before.
[update documentation and commit message, rebase to current master,
switch back to DT instead of sysfs]
Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20210430175038.103226-2-sebastian.reichel@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There's no need to initialise irq-flags variables before saving the
interrupt state.
Drop the redundant initialisations from drivers that got this wrong.
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210519092541.10137-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Force-threaded interrupt handlers used to run with interrupts enabled,
something which could lead to deadlocks in case a threaded handler
shared a lock with code running in hard interrupt context (e.g. timer
callbacks) and did not explicitly disable interrupts.
This was specifically the case for serial drivers that take the port
lock in their console write path as printk can be called from hard
interrupt context also with forced threading ("threadirqs").
Since commit 81e2073c17 ("genirq: Disable interrupts for force
threaded handlers") interrupt handlers always run with interrupts
disabled on non-RT so that drivers no longer need to do handle this.
Drop the now obsolete workaround added by commit 33f16855dc ("tty:
serial: imx: fix potential deadlock").
Cc: Sam Nobs <samuel.nobs@taitradio.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210322111036.31966-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This really eliminates multiplications from the assembly. I would have
thought they are optimized by inlining ktime_set, but not on x86_64 with
gcc 10.
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210302062214.29627-10-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that the driver only probes via devicetree, we can move the
content of imx_uart_probe_dt() directly into imx_uart_probe() to
make the code simpler.
Suggested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20201209214712.15247-1-festevam@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since 5.10-rc1 i.MX is a devicetree-only platform and the NULL check on
of_device_get_match_data() is no longer needed.
This check was only needed when this driver supported both DT and non-DT
platforms.
Remove the unneeded of_device_get_match_data() NULL check.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20201126124643.3371-1-festevam@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As described in Documentation, poll_init() is called by kgdb to initialize
hardware which supports both poll_put_char() and poll_get_char().
It's necessary to enable TXEN bit, otherwise, it will cause hardware fault
and kernel panic when calling imx_poll_put_char().
Generally, if use /dev/ttymxc0 as kgdb console as well as system
console, ttymxc0 is initialized early by system console which does enable
TXEN bit.But when use /dev/ttymxc1 as kgbd console, ttymxc1 is only
initialized by imx_poll_init() cannot enable the TXEN bit, which will
cause kernel panic.
Signed-off-by: Mingrui Ren <jiladahe1997@gmail.com>
Link: https://lore.kernel.org/r/20201202072543.151-1-972931182@qq.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge 5.10-rc5 into tty-next
We need the tty/serial fixes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since 5.10-rc1 i.MX is a devicetree-only platform and the existing
.id_table support in this driver was only useful for old non-devicetree
platforms.
Get rid of the .id_table since it is no longer used.
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20201115110341.22761-1-festevam@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Since 5.10-rc1 i.MX is a devicetree-only platform and the existing
platform data support in this driver was only useful for old non-devicetree
platforms.
Get rid of the platform data support since it is no longer used.
Reviewed-by: Fugang Duan <fugang.duan@nxp.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20201110214840.16768-1-festevam@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Enabling the lock dependency validator has revealed
that the way spinlocks are used in the IMX serial
port could result in a deadlock.
Specifically, imx_uart_int() acquires a spinlock
without disabling the interrupts, meaning that another
interrupt could come along and try to acquire the same
spinlock, potentially causing the two to wait for each
other indefinitely.
Use spin_lock_irqsave() instead to disable interrupts
upon acquisition of the spinlock.
Fixes: c974991d26 ("tty:serial:imx: use spin_lock instead of spin_lock_irqsave in isr")
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sam Nobs <samuel.nobs@taitradio.com>
Link: https://lore.kernel.org/r/1604955006-9363-1-git-send-email-samuel.nobs@taitradio.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The IPG clock is disabled at the end of imx_uart_shutdown(); we really
don't want to run any IRQ handlers after this point.
At least on i.MX8MN, the UART will happily continue to generate interrupts
even with its clocks disabled, but in this state, all register writes are
ignored (which will cause the shadow registers to differ from the actual
register values, resulting in all kinds of weirdness).
In a transfer without DMA, this could lead to the following sequence of
events:
- The UART finishes its transmission while imx_uart_shutdown() is run,
triggering the TXDC interrupt (we can trigger this fairly reliably by
writing a single byte to the TTY and closing it right away)
- imx_uart_shutdown() finishes, disabling the UART clocks
- imx_uart_int() -> imx_uart_transmit_buffer() -> imx_uart_stop_tx()
imx_uart_stop_tx() should now clear UCR4_TCEN to disable the TXDC
interrupt, but this register write is ineffective. This results in an
interrupt storm.
To disable all interrupts in the same place, and to avoid setting UCR4
twice, clearing UCR4_OREN is moved below del_timer_sync() as well; this
should be harmless.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20200925082412.12960-1-matthias.schiffer@ew.tq-group.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When calculate "ucr1" UCR1_TRDYEN is duplicate.
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200903062401.692442-1-yebin10@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add support for building i.MX serial driver as module.
The changes of the patch:
- imx console driver can be built as module.
- move out earlycon code to separated driver like imx_earlycon.c,
and imx earlycon driver only support build-in.
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
Link: https://lore.kernel.org/r/20200724070815.11445-2-fugang.duan@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This patch imitates 6e0a5de213 ("serial: 8250: Use hrtimers for
rs485 delays") in replacing the previously used classic timers
with hrtimers. The old way provided a too coarse resolution on
systems with configs of less than 1000 HZ.
Use of hrtimers addresses this and can be easily extended to
support microsecond resolution in future when support
for this arrives upstream.
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20200714093012.21621-3-uwe@kleine-koenig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This adds support for delays between assertion of RTS (which is supposed
to enable the rs485 transmitter) and sending as well as between the last
send char and deassertionof RTS.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200714093012.21621-2-uwe@kleine-koenig.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 8f065acec7.
There has been a quick fix against uninitialised lock revealed by
the commit f743061a85 ("serial: core: Initialise spin lock before use
in uart_configure_port()"). Since we have now better fix in serial core,
this may be safely reverted.
Fixes: 8f065acec7 ("serial: imx: Initialize lock for non-registered console")
Depends-on: f743061a85 ("serial: core: Initialise spin lock before use in uart_configure_port()")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200711135346.71171-4-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The AGTIM flag must be cleared explicitly, otherwise the IRQ handler
will be called in an endless loop.
Fortunately, this issue currently doesn't affect mainline kernels in
practice, as the the RX FIFO trigger level is set to 1 in UFCR. When
setting the trigger level to a higher number, the issue is trivially
reproducible by any RX without DMA that doesn't fill the FIFO up to the
configured level.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20200528154747.14201-1-matthias.schiffer@ew.tq-group.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit a3cb39d258
("serial: core: Allow detach and attach serial device for console")
changed a bit logic behind lock initialization since for most of the console
driver it's supposed to have lock already initialized even if console is not
enabled. However, it's not the case for Freescale IMX console.
Initialize lock explicitly in the ->probe().
Note, there is still an open question should or shouldn't not this driver
register console properly.
Fixes: a3cb39d258 ("serial: core: Allow detach and attach serial device for console")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200525105952.13744-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We're about to amend uart_get_rs485_mode() to support a GPIO pin for
rs485 bus termination. Retrieving the GPIO descriptor may fail, so
allow uart_get_rs485_mode() to return an errno and change all callers
to check for failure.
The GPIO descriptor is going to be stored in struct uart_port. Pass
that struct to uart_get_rs485_mode() in lieu of a struct device and
struct serial_rs485, both of which are directly accessible from struct
uart_port.
A few drivers call uart_get_rs485_mode() before setting the struct
device pointer in struct uart_port. Shuffle those calls around where
necessary.
[Heiko Stuebner did the ar933x_uart.c portion, hence his Signed-off-by.]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/271e814af4b0db3bffbbb74abf2b46b75add4516.1589285873.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The peripheral has support for inverting its input and/or output
signals. This is useful if the hardware flips polarity of the
peripheral's signal, such as swapped +/- pins on an RS-422 transceiver,
or an inverting level shifter. Add support for these control registers
via the device tree binding.
As part of this change, make the writes of the various registers more
uniform by moving the UCR3 block up near the other registers' blocks,
since the INVT bit must be set before enabling the peripheral.
Signed-off-by: George Hilliard <ghilliard@kopismobile.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200226222319.18383-3-ghilliard@kopismobile.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The main irq handler function starts by first masking disabled
interrupts in the status register values to ensure to only handle
enabled interrupts. This is important as when the RX path in the
hardware is disabled reading the RX fifo results in an external abort.
This checking must be done under the port lock, otherwise the following
can happen:
CPU1 | CPU2
|
irq triggers as there are chars |
in the RX fifo |
| grab port lock
imx_uart_int finds RRDY enabled |
and calls imx_uart_rxint which |
has to wait for port lock |
| disable RX (e.g. because we're
| using RS485 with !RX_DURING_TX)
|
| release port lock
read from RX fifo with RX |
disabled => exception |
So take the port lock only once in imx_uart_int() instead of in the
functions called from there.
Reported-by: Andre Renaud <arenaud@designa-electronics.com>
Cc: stable@vger.kernel.org
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20200121071702.20150-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
