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UART011_CR_RXE is set in pl011_startup() during normal initialization, and
cleared by pl011_disable_uart() during port shutdown.
You can use a none-console port in poll mode like kgdboc does with
tty_find_polling_driver() after a port shutdown. But pl011_startup() is not
called in tty_find_polling_driver(). So you need to set UART011_CR_RXE to
reenable receive function.
Not sure setting UART011_CR_RXE in pl011_set_termios() is a good idea
through.
Signed-off-by: Hongyu Xie <xiehongyu1@kylinos.cn>
Link: https://lore.kernel.org/r/20230501070909.1144547-1-xiehongyu1@kylinos.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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In RS485 mode the transmission of a high priority character fails since it
is written to the data register before the transmitter is enabled. Fix this
in pl011_tx_chars() by enabling RS485 transmission before writing the
character.
Fixes: 8d479237727c ("serial: amba-pl011: add RS485 support")
Cc: stable@vger.kernel.org
Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Link: https://lore.kernel.org/r/20230108181735.10937-1-LinoSanfilippo@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Clearing the RX FIFO will cause data loss.
Copy the pl011_enabl_interrupts implementation, and remove the clear
interrupt and FIFO part of the code.
Fixes: 211565b10099 ("serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle")
Signed-off-by: delisun <delisun@pateo.com.cn>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221110020108.7700-1-delisun@pateo.com.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Chapter "B Generic UART" in "ARM Server Base System Architecture" [1]
documentation describes a generic UART interface. Such generic UART
does not support DMA. In current code, sbsa_uart_pops and
amba_pl011_pops share the same stop_rx operation, which will invoke
pl011_dma_rx_stop, leading to an access of the DMACR register. This
commit adds a using_rx_dma check in pl011_dma_rx_stop to avoid the
access to DMACR register for SBSA UARTs which does not support DMA.
When the kernel enables DMA engine with "CONFIG_DMA_ENGINE=y", Linux
SBSA PL011 driver will access PL011 DMACR register in some functions.
For most real SBSA Pl011 hardware implementations, the DMACR write
behaviour will be ignored. So these DMACR operations will not cause
obvious problems. But for some virtual SBSA PL011 hardware, like Xen
virtual SBSA PL011 (vpl011) device, the behaviour might be different.
Xen vpl011 emulation will inject a data abort to guest, when guest is
accessing an unimplemented UART register. As Xen VPL011 is SBSA
compatible, it will not implement DMACR register. So when Linux SBSA
PL011 driver access DMACR register, it will get an unhandled data abort
fault and the application will get a segmentation fault:
Unhandled fault at 0xffffffc00944d048
Mem abort info:
ESR = 0x96000000
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x00: ttbr address size fault
Data abort info:
ISV = 0, ISS = 0x00000000
CM = 0, WnR = 0
swapper pgtable: 4k pages, 39-bit VAs, pgdp=0000000020e2e000
[ffffffc00944d048] pgd=100000003ffff803, p4d=100000003ffff803, pud=100000003ffff803, pmd=100000003fffa803, pte=006800009c090f13
Internal error: ttbr address size fault: 96000000 [#1] PREEMPT SMP
...
Call trace:
pl011_stop_rx+0x70/0x80
tty_port_shutdown+0x7c/0xb4
tty_port_close+0x60/0xcc
uart_close+0x34/0x8c
tty_release+0x144/0x4c0
__fput+0x78/0x220
____fput+0x1c/0x30
task_work_run+0x88/0xc0
do_notify_resume+0x8d0/0x123c
el0_svc+0xa8/0xc0
el0t_64_sync_handler+0xa4/0x130
el0t_64_sync+0x1a0/0x1a4
Code: b9000083 b901f001 794038a0 8b000042 (b9000041)
---[ end trace 83dd93df15c3216f ]---
note: bootlogd[132] exited with preempt_count 1
/etc/rcS.d/S07bootlogd: line 47: 132 Segmentation fault start-stop-daemon
This has been discussed in the Xen community, and we think it should fix
this in Linux. See [2] for more information.
[1] https://developer.arm.com/documentation/den0094/c/?lang=en
[2] https://lists.xenproject.org/archives/html/xen-devel/2022-11/msg00543.html
Fixes: 0dd1e247fd39 (drivers: PL011: add support for the ARM SBSA generic UART)
Signed-off-by: Jiamei Xie <jiamei.xie@arm.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Link: https://lore.kernel.org/r/20221117103237.86856-1-jiamei.xie@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Take advantage of the new uart_xmit_advance() helper.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019091151.6692-9-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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>
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Some of the implementations can read only 32 bits because of
the interface limitations of the port they are connected to.
Add a parameter reg-io-width for supporting such platforms.
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
Link: https://lore.kernel.org/r/20220826120559.2122-3-shubhrajyoti.datta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty / serial driver updates from Greg KH:
"Here is the big set of tty and serial driver changes for 6.0-rc1.
It was delayed from last week as I wanted to make sure the last commit
here got some good testing in linux-next and elsewhere as it seemed to
show up only late in testing for some reason.
Nothing major here, just lots of cleanups from Jiri and Ilpo to make
the tty core cleaner (Jiri) and the rs485 code simpler to use (Ilpo).
Also included in here is the obligatory n_gsm updates from Daniel
Starke and lots of tiny driver updates and minor fixes and tweaks for
other smaller serial drivers.
All of these have been in linux-next for a while with no reported
problems"
* tag 'tty-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (186 commits)
tty: serial: qcom-geni-serial: Fix %lu -> %u in print statements
tty: amiserial: Fix comment typo
tty: serial: document uart_get_console()
tty: serial: serial_core, reformat kernel-doc for functions
Documentation: serial: link uart_ops properly
Documentation: serial: move GPIO kernel-doc to the functions
Documentation: serial: dedup kernel-doc for uart functions
Documentation: serial: move uart_ops documentation to the struct
dt-bindings: serial: snps-dw-apb-uart: Document Rockchip RV1126
serial: mvebu-uart: uart2 error bits clearing
tty: serial: fsl_lpuart: correct the count of break characters
serial: stm32: make info structs static to avoid sparse warnings
serial: fsl_lpuart: zero out parity bit in CS7 mode
tty: serial: qcom-geni-serial: Fix get_clk_div_rate() which otherwise could return a sub-optimal clock rate.
serial: 8250_bcm2835aux: Add missing clk_disable_unprepare()
tty: vt: initialize unicode screen buffer
serial: remove VR41XX serial driver
serial: 8250: lpc18xx: Remove redundant sanity check for RS485 flags
serial: 8250_dwlib: remove redundant sanity check for RS485 flags
dt_bindings: rs485: Correct delay values
...
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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>
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The driver must provide throttle and unthrottle in uart_ops when it
sets UPSTAT_AUTORTS. Add them using existing stop_rx &
enable_interrupts functions.
Fixes: 2a76fa283098 (serial: pl011: Adopt generic flag to store auto RTS status)
Cc: stable <stable@kernel.org>
Cc: Lukas Wunner <lukas@wunner.de>
Reported-by: Nuno Gonçalves <nunojpg@gmail.com>
Tested-by: Nuno Gonçalves <nunojpg@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220614075637.8558-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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>
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Serial core handles serial_rs485 sanitization.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-30-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add information on supported serial_rs485 features.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-13-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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There is no point keeping the header content separated. In this case, it
is only an enum. So move the enum to the appropriate source file.
Cc: Russell King <linux@armlinux.org.uk>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220519075720.31402-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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We need the tty/serial fixes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The current timeout for draining the tx fifo in RS485 mode is calculated by
multiplying the time it takes to transmit one character (with the given
baud rate) with the maximal number of characters in the tx queue.
This timeout is too short for two reasons:
First when calculating the time to transmit one character integer division
is used which may round down the result in case of a remainder of the
division.
Fix this by rounding up the division result.
Second the hardware may need additional time (e.g for first putting the
characters from the fifo into the shift register) before the characters are
actually put onto the wire.
To be on the safe side double the current maximum number of iterations
that are used to wait for the queue draining.
Fixes: 8d479237727c ("serial: amba-pl011: add RS485 support")
Cc: stable@vger.kernel.org
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220408233503.7251-1-LinoSanfilippo@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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In uart_set_rs485_config() the serial core already
- ensures that only one of both options RTS on send or RTS after send is
set
- nullifies the padding field of the passed serial_rs485 struct
- clamps the RTS delays
- assigns the passed serial_rs485 struct to the uart port
So remove these tasks from the code of the drivers rs485_config() function
to avoid redundancy.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20220410104642.32195-3-LinoSanfilippo@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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>
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RTS polarity of rs485-enabled ports is currently initialized on uart
open via:
tty_port_open()
tty_port_block_til_ready()
tty_port_raise_dtr_rts() # if (C_BAUD(tty))
uart_dtr_rts()
uart_port_dtr_rts()
There's at least three problems here:
First, if no baud rate is set, RTS polarity is not initialized.
That's the right thing to do for rs232, but not for rs485, which
requires that RTS is deasserted unconditionally.
Second, if the DeviceTree property "linux,rs485-enabled-at-boot-time" is
present, RTS should be deasserted as early as possible, i.e. on probe.
Otherwise it may remain asserted until first open.
Third, even though RTS is deasserted on open and close, it may
subsequently be asserted by uart_throttle(), uart_unthrottle() or
uart_set_termios() because those functions aren't rs485-aware.
(Only uart_tiocmset() is.)
To address these issues, move RTS initialization from uart_port_dtr_rts()
to uart_configure_port(). Prevent subsequent modification of RTS
polarity by moving the existing rs485 check from uart_tiocmget() to
uart_update_mctrl().
That way, RTS is initialized on probe and then remains unmodified unless
the uart transmits data. If rs485 is enabled at runtime (instead of at
boot) through a TIOCSRS485 ioctl(), RTS is initialized by the uart
driver's ->rs485_config() callback and then likewise remains unmodified.
The PL011 driver initializes RTS on uart open and prevents subsequent
modification in its ->set_mctrl() callback. That code is obsoleted by
the present commit, so drop it.
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Su Bao Cheng <baocheng.su@siemens.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/2d2acaf3a69e89b7bf687c912022b11fd29dfa1e.1642909284.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Commit 8d479237727c ("serial: amba-pl011: add RS485 support") sought to
keep RTS deasserted on set_mctrl if rs485 is enabled. However it did so
only if deasserted RTS polarity is high. Fix it in case it's low.
Fixes: 8d479237727c ("serial: amba-pl011: add RS485 support")
Cc: stable@vger.kernel.org # v5.15+
Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Jochen Mades <jochen@mades.net>
[lukas: copyedit commit message, add stable designation]
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/85fa3323ba8c307943969b7343e23f34c3e652ba.1642909284.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Commit d8d8ffa47783 ("amba-pl011: do not disable RTS during shutdown")
amended the PL011 serial driver to leave DTR/RTS polarity untouched on
tty close. That change made sense.
But the commit also added code to save DTR/RTS state to an internal
variable on tty close and restore it on tty open. That part of the
commit makes less sense: The driver has no ->pm() callback, so the uart
remains powered after tty close and automatically preserves register
state, including DTR/RTS.
Saving and restoring registers isn't the job of the ->startup() and
->shutdown() callbacks anyway. Rather, it should happen in ->pm().
Additionally, after pl011_startup() restores the state, the serial core
overrides it in uart_port_dtr_rts() if a baud rate has been set:
tty_port_open()
uart_port_activate()
uart_startup()
uart_port_startup()
pl011_startup() # restores DTR/RTS from uap->old_cr
tty_port_block_til_ready()
tty_port_raise_dtr_rts # if (C_BAUD(tty))
uart_dtr_rts()
uart_port_dtr_rts() # raises DTR/RTS
The serial core also overrides DTR/RTS on tty close in uart_shutdown()
if C_HUPCL(tty) is set. So a user-defined DTR/RTS polarity won't
survive a close/open cycle anyway, unless the user has set the baud rate
to zero and disabled hupcl on the tty.
Bottom line is, the code to save and restore DTR/RTS has no effect.
Remove it.
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/e22089ab49e6e78822c50c8c4db46bf3ee885623.1641129328.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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pl011_set_termios() briefly resets the CR register to zero, thereby
glitching DTR/RTS signals. With rs485 this may result in the bus being
occupied for no reason.
Where does this register write originate from?
The PL011 driver was forked from the PL010 driver in 2004:
https://git.kernel.org/history/history/c/157c0342e591
Until this commit, the PL010 driver's IRQ handler ambauart_int()
modified the CR register without holding the port spinlock.
ambauart_set_termios() also modified that register. To prevent
concurrent read-modify-writes by the IRQ handler and to prevent
transmission while changing baudrate, ambauart_set_termios() had to
disable interrupts. On the PL010, that is achieved by writing zero to
the CR register.
However, on the PL011, interrupts are disabled in the IMSC register,
not in the CR register.
Additionally, the commit amended both the PL010 and PL011 driver to
acquire the port spinlock in the IRQ handler, obviating the need to
disable interrupts in ->set_termios().
So the CR register write is obsolete for two reasons. Drop it.
Cc: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/f49f945375f5ccb979893c49f1129f51651ac738.1641129062.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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We need the tty/serial driver fixes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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With commit 3873e2d7f63a ("drivers: PL011: refactor pl011_probe()") the
function devm_ioremap() called from pl011_setup_port() was replaced with
devm_ioremap_resource(). Since this function not only remaps but also
requests the ports io memory region it now collides with the .config_port()
callback which requests the same region at uart port registration.
Since devm_ioremap_resource() already claims the memory successfully, the
request in .config_port() fails.
Later at uart port deregistration the attempt to release the unclaimed
memory also fails. The failure results in a “Trying to free nonexistent
resource" warning.
Fix these issues by removing the callbacks that implement the redundant
memory allocation/release. Also make sure that changing the drivers io
memory base address via TIOCSSERIAL is not allowed any more.
Fixes: 3873e2d7f63a ("drivers: PL011: refactor pl011_probe()")
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20211129174238.8333-1-LinoSanfilippo@gmx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Commit 89d4f98ae90d ("ARM: remove zte zx platform") missed to remove some
definitions for this platform's debug and serial, e.g., code dependent on
the config DEBUG_ZTE_ZX.
Fortunately, ./scripts/checkkconfigsymbols.py detects this and warns:
DEBUG_ZTE_ZX
Referencing files: arch/arm/include/debug/pl01x.S
Further review by Arnd Bergmann identified even more dead code in the
amba serial driver.
Remove all this left-over from the zte zx platform.
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20211102063810.932-1-lukas.bulwahn@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The document 'ACPI for Arm Components 1.0' defines the following
_HID mappings:
-'Prime cell UART (PL011)': ARMH0011
-'SBSA UART': ARMHB000
Use the sbsa-uart driver when a device is described with
the 'ARMHB000' _HID.
Note:
PL011 devices currently use the sbsa-uart driver instead of the
uart-pl011 driver. Indeed, PL011 devices are not bound to a clock
in ACPI. It is not possible to change their baudrate.
Cc: <stable@vger.kernel.org>
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Link: https://lore.kernel.org/r/20211109172248.19061-1-Pierre.Gondois@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
This reverts commit b0819465be8be0c76af15436a9e6db4dab4c196e which
results in amba_device-specific code being called from
sbsa_uart_startup() and sbsa_uart_shutdown().
Signed-off-by: Qian Cai <quic_qiancai@quicinc.com>
Link: https://lore.kernel.org/r/20210813163135.205-1-quic_qiancai@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
In order to make pl011 work better, multiple interrupts are
required, such as TXIM, RXIM, RTIM, error interrupt(FE/PE/BE/OE);
at the same time, pl011 to GIC does not merge the interrupt
lines(each serial-interrupt corresponding to different GIC hardware
interrupt), so need to enable and request multiple gic interrupt
numbers in the driver.
Signed-off-by: Bing Fan <tombinfan@tencent.com>
Link: https://lore.kernel.org/r/1625103512-30182-1-git-send-email-hptsfb@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Add basic support for RS485: Provide a callback to configure RS485
settings. Handle the RS485 specific part in the functions
pl011_rs485_tx_start() and pl011_rs485_tx_stop() which extend the generic
start/stop callbacks.
Beside via IOCTL from userspace RS485 can be enabled by means of the
device tree property "rs485-enabled-at-boot-time".
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Link: https://lore.kernel.org/r/20210630225644.3744-1-LinoSanfilippo@gmx.de
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>
|
|
Commit ead76f329f77 ("ARM: 6763/1: pl011: add optional RX DMA to PL011
v2") added RX DMA support and also reproduced the workaround for the
infamous low_latency behaviour of tty_flip_buffer_push() by dropping and
reacquiring the port lock during receive processing.
Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
tty_flip_buffer_push() always schedules a work item to push data to the
line discipline and there's no need to keep any low_latency hacks around.
Note that the port lock is also dropped in the PIO path
(see pl011_rx_chars), but it is not clear whether this is still needed
by the DMA code added by the aforementioned commit.
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Russell King <linux@armlinux.org.uk>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210421095509.3024-6-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
All amba drivers return 0 in their remove callback. Together with the
driver core ignoring the return value anyhow, it doesn't make sense to
return a value here.
Change the remove prototype to return void, which makes it explicit that
returning an error value doesn't work as expected. This simplifies changing
the core remove callback to return void, too.
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org> # for drivers/memory
Acked-by: Mark Brown <broonie@kernel.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com> # for hwtracing/coresight
Acked-By: Vinod Koul <vkoul@kernel.org> # for dmaengine
Acked-by: Guenter Roeck <linux@roeck-us.net> # for watchdog
Acked-by: Wolfram Sang <wsa@kernel.org> # for I2C
Acked-by: Takashi Iwai <tiwai@suse.de> # for sound
Acked-by: Vladimir Zapolskiy <vz@mleia.com> # for memory/pl172
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20210126165835.687514-5-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
|
|
When !ACPI 'sbsa_uart_acpi_match' is not referenced.
Fixes the following W=1 kernel build warning(s):
drivers/tty/serial/amba-pl011.c:2792:36: warning: ‘sbsa_uart_acpi_match’ defined but not used [-Wunused-const-variable=]
Cc: Russell King <linux@armlinux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104193549.4026187-18-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Issuing a magic-sysrq via the PL011 causes the following lockdep splat,
which is easily reproducible under QEMU:
| sysrq: Changing Loglevel
| sysrq: Loglevel set to 9
|
| ======================================================
| WARNING: possible circular locking dependency detected
| 5.9.0-rc7 #1 Not tainted
| ------------------------------------------------------
| systemd-journal/138 is trying to acquire lock:
| ffffab133ad950c0 (console_owner){-.-.}-{0:0}, at: console_lock_spinning_enable+0x34/0x70
|
| but task is already holding lock:
| ffff0001fd47b098 (&port_lock_key){-.-.}-{2:2}, at: pl011_int+0x40/0x488
|
| which lock already depends on the new lock.
[...]
| Possible unsafe locking scenario:
|
| CPU0 CPU1
| ---- ----
| lock(&port_lock_key);
| lock(console_owner);
| lock(&port_lock_key);
| lock(console_owner);
|
| *** DEADLOCK ***
The issue being that CPU0 takes 'port_lock' on the irq path in pl011_int()
before taking 'console_owner' on the printk() path, whereas CPU1 takes
the two locks in the opposite order on the printk() path due to setting
the "console_owner" prior to calling into into the actual console driver.
Fix this in the same way as the msm-serial driver by dropping 'port_lock'
before handling the sysrq.
Cc: <stable@vger.kernel.org> # 4.19+
Cc: Russell King <linux@armlinux.org.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20200811101313.GA6970@willie-the-truck
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Will Deacon <will@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200930120432.16551-1-will@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
If probing of a pl011 gets deferred until after free_initmem(), an oops
ensues because pl011_console_match() is called which has been freed.
Fix by removing the __init attribute from the function and those it
calls.
Commit 10879ae5f12e ("serial: pl011: add console matching function")
introduced pl011_console_match() not just for early consoles but
regular preferred consoles, such as those added by acpi_parse_spcr().
Regular consoles may be registered after free_initmem() for various
reasons, one being deferred probing, another being dynamic enablement
of serial ports using a DeviceTree overlay.
Thus, pl011_console_match() must not be declared __init and the
functions it calls mustn't either.
Stack trace for posterity:
Unable to handle kernel paging request at virtual address 80c38b58
Internal error: Oops: 8000000d [#1] PREEMPT SMP ARM
PC is at pl011_console_match+0x0/0xfc
LR is at register_console+0x150/0x468
[<80187004>] (register_console)
[<805a8184>] (uart_add_one_port)
[<805b2b68>] (pl011_register_port)
[<805b3ce4>] (pl011_probe)
[<80569214>] (amba_probe)
[<805ca088>] (really_probe)
[<805ca2ec>] (driver_probe_device)
[<805ca5b0>] (__device_attach_driver)
[<805c8060>] (bus_for_each_drv)
[<805c9dfc>] (__device_attach)
[<805ca630>] (device_initial_probe)
[<805c90a8>] (bus_probe_device)
[<805c95a8>] (deferred_probe_work_func)
Fixes: 10879ae5f12e ("serial: pl011: add console matching function")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v4.10+
Cc: Aleksey Makarov <amakarov@marvell.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Christopher Covington <cov@codeaurora.org>
Link: https://lore.kernel.org/r/f827ff09da55b8c57d316a1b008a137677b58921.1597315557.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
pl011_probe() calls pl011_setup_port() to reserve an amba_ports[] entry,
then calls pl011_register_port() to register the uart driver with the
tty layer.
If registration of the uart driver fails, the amba_ports[] entry is not
released. If this happens 14 times (value of UART_NR macro), then all
amba_ports[] entries will have been leaked and driver probing is no
longer possible. (To be fair, that can only happen if the DeviceTree
doesn't contain alias IDs since they cause the same entry to be used for
a given port.) Fix it.
Fixes: ef2889f7ffee ("serial: pl011: Move uart_register_driver call to device")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v3.15+
Cc: Tushar Behera <tushar.behera@linaro.org>
Link: https://lore.kernel.org/r/138f8c15afb2f184d8102583f8301575566064a6.1597316167.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
This reverts commit 8508f4cba308f785b2fd4b8c38849c117b407297.
There has been a quick fix against uninitialised lock revealed by
the commit f743061a85f5 ("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: 8508f4cba308 ("serial: amba-pl011: Make sure we initialize the port.lock spinlock")
Depends-on: f743061a85f5 ("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/20200711135346.71171-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial driver updates from Greg KH:
"Here is the tty and serial driver updates for 5.8-rc1
Nothing huge at all, just a lot of little serial driver fixes, updates
for new devices and features, and other small things. Full details are
in the shortlog.
All of these have been in linux-next with no issues for a while"
* tag 'tty-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (67 commits)
tty: serial: qcom_geni_serial: Add 51.2MHz frequency support
tty: serial: imx: clear Ageing Timer Interrupt in handler
serial: 8250_fintek: Add F81966 Support
sc16is7xx: Add flag to activate IrDA mode
dt-bindings: sc16is7xx: Add flag to activate IrDA mode
serial: 8250: Support rs485 bus termination GPIO
serial: 8520_port: Fix function param documentation
dt-bindings: serial: Add binding for rs485 bus termination GPIO
vt: keyboard: avoid signed integer overflow in k_ascii
serial: 8250: Enable 16550A variants by default on non-x86
tty: hvc_console, fix crashes on parallel open/close
serial: imx: Initialize lock for non-registered console
sc16is7xx: Read the LSR register for basic device presence check
sc16is7xx: Allow sharing the IRQ line
sc16is7xx: Use threaded IRQ
sc16is7xx: Always use falling edge IRQ
tty: n_gsm: Fix bogus i++ in gsm_data_kick
tty: n_gsm: Remove unnecessary test in gsm_print_packet()
serial: stm32: add no_console_suspend support
tty: serial: fsl_lpuart: Use __maybe_unused instead of #if CONFIG_PM_SLEEP
...
|
|
Implement the read() function in the early console driver. With
recently added kgdboc_earlycon feature, this allows you to use kgdb
to debug fairly early into the system boot.
We only bother implementing this if polling is enabled since kgdb can't
be enabled without that.
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200507130644.v4.12.I8ee0811f0e0816dd8bfe7f2f5540b3dba074fae8@changeid
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
|
|
Valentine reported seeing:
[ 3.626638] INFO: trying to register non-static key.
[ 3.626639] the code is fine but needs lockdep annotation.
[ 3.626640] turning off the locking correctness validator.
[ 3.626644] CPU: 7 PID: 51 Comm: kworker/7:1 Not tainted 5.7.0-rc2-00115-g8c2e9790f196 #116
[ 3.626646] Hardware name: HiKey960 (DT)
[ 3.626656] Workqueue: events deferred_probe_work_func
[ 3.632476] sd 0:0:0:0: [sda] Optimal transfer size 8192 bytes not a multiple of physical block size (16384 bytes)
[ 3.640220] Call trace:
[ 3.640225] dump_backtrace+0x0/0x1b8
[ 3.640227] show_stack+0x20/0x30
[ 3.640230] dump_stack+0xec/0x158
[ 3.640234] register_lock_class+0x598/0x5c0
[ 3.640235] __lock_acquire+0x80/0x16c0
[ 3.640236] lock_acquire+0xf4/0x4a0
[ 3.640241] _raw_spin_lock_irqsave+0x70/0xa8
[ 3.640245] uart_add_one_port+0x388/0x4b8
[ 3.640248] pl011_register_port+0x70/0xf0
[ 3.640250] pl011_probe+0x184/0x1b8
[ 3.640254] amba_probe+0xdc/0x180
[ 3.640256] really_probe+0xe0/0x338
[ 3.640257] driver_probe_device+0x60/0xf8
[ 3.640259] __device_attach_driver+0x8c/0xd0
[ 3.640260] bus_for_each_drv+0x84/0xd8
[ 3.640261] __device_attach+0xe4/0x140
[ 3.640263] device_initial_probe+0x1c/0x28
[ 3.640265] bus_probe_device+0xa4/0xb0
[ 3.640266] deferred_probe_work_func+0x7c/0xb8
[ 3.640269] process_one_work+0x2c0/0x768
[ 3.640271] worker_thread+0x4c/0x498
[ 3.640272] kthread+0x14c/0x158
[ 3.640275] ret_from_fork+0x10/0x1c
Which seems to be due to the fact that after allocating the uap
structure, nothing initializes the spinlock.
Its a little confusing, as uart_port_spin_lock_init() is one
place where the lock is supposed to be initialized, but it has
an exception for the case where the port is a console.
This makes it seem like a deeper fix is needed to properly
register the console, but I'm not sure what that entails, and
Andy suggested that this approach is less invasive.
Thus, this patch resolves the issue by initializing the spinlock
in the driver, and resolves the resulting warning.
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
Reported-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Reviewed-and-tested-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lore.kernel.org/r/20200428184050.6501-1-john.stultz@linaro.org
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: Russell King <linux@armlinux.org.uk>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-10-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Add the suspend and resume handlers for the versal uart platform driver.
Adds the suspend for sbsa driver.
Sbsa is a subset of the pl011 driver.
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/1575873048-14313-1-git-send-email-shubhrajyoti.datta@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Fix the following warning:
drivers/tty/serial/amba-pl011.c: In function check_apply_cts_event_workaround:
drivers/tty/serial/amba-pl011.c:1461:15: warning: variable dummy_read set but not used [-Wunused-but-set-variable]
The data read is useless and can be dropped.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Link: https://lore.kernel.org/r/1575619526-34482-1-git-send-email-wangxiongfeng2@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
PL011's ->flush_buffer() implementation releases and reacquires the port
lock. Due to a race condition here, data can end up being added to the
circular buffer but neither being discarded nor being sent out. This
leads to, for example, tcdrain(2) waiting indefinitely.
Process A Process B
uart_flush_buffer()
- acquire lock
- circ_clear
- pl011_flush_buffer()
-- release lock
-- dmaengine_terminate_all()
uart_write()
- acquire lock
- add chars to circ buffer
- start_tx()
-- start DMA
- release lock
-- acquire lock
-- turn off DMA
-- release lock
// Data in circ buffer but DMA is off
According to the comment in the code, the releasing of the lock around
dmaengine_terminate_all() is to avoid a deadlock with the DMA engine
callback. However, since the time this code was written, the DMA engine
API documentation seems to have been clarified to say that
dmaengine_terminate_all() (in the identically implemented but
differently named dmaengine_terminate_async() variant) does not wait for
any running complete callback to be completed and can even be called
from a complete callback. So there is no possibility of deadlock if the
DMA engine driver implements this API correctly.
So we should be able to just remove this release and reacquire of the
lock to prevent the aforementioned race condition.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191118092547.32135-1-vincent.whitchurch@axis.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
dma_request_slave_channel_reason() is:
#define dma_request_slave_channel_reason(dev, name) \
dma_request_chan(dev, name)
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20191113094618.1725-2-peter.ujfalusi@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
pl011_dma_probe() is only used in pl011_dma_startup() which does only
exist when CONFIG_DMA_ENGINE=y, so remove the unused dummy version to
silence the warning.
Signed-off-by: Qian Cai <cai@lca.pw>
Link: https://lore.kernel.org/r/1568726340-4518-1-git-send-email-cai@lca.pw
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
We don't need dev_err() messages when platform_get_irq() fails now that
platform_get_irq() prints an error message itself when something goes
wrong. Let's remove these prints with a simple semantic patch.
// <smpl>
@@
expression ret;
struct platform_device *E;
@@
ret =
(
platform_get_irq(E, ...)
|
platform_get_irq_byname(E, ...)
);
if ( \( ret < 0 \| ret <= 0 \) )
{
(
-if (ret != -EPROBE_DEFER)
-{ ...
-dev_err(...);
-... }
|
...
-dev_err(...);
)
...
}
// </smpl>
While we're here, remove braces on if statements that only have one
statement (manually).
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20190730181557.90391-45-swboyd@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
The PL011 register space includes all necessary status bits to
determine whether a device instance requires handling in response
to an interrupt. Therefore, multiple instances of the device could
be serviced by a single shared interrupt, which is the case on BCM7211.
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
When the test 'CONFIG_DEBUG_TEST_DRIVER_REMOVE=y' is enabled,
arch_initcall(pl011_init) came before subsys_initcall(default_bdi_init).
devtmpfs gets killed because we try to remove a file and decrement the
wb reference count before the noop_backing_device_info gets initialized.
[ 0.332075] Serial: AMBA PL011 UART driver
[ 0.485276] 9000000.pl011: ttyAMA0 at MMIO 0x9000000 (irq = 39, base_baud = 0) is a PL011 rev1
[ 0.502382] console [ttyAMA0] enabled
[ 0.515710] Unable to handle kernel paging request at virtual address 0000800074c12000
[ 0.516053] Mem abort info:
[ 0.516222] ESR = 0x96000004
[ 0.516417] Exception class = DABT (current EL), IL = 32 bits
[ 0.516641] SET = 0, FnV = 0
[ 0.516826] EA = 0, S1PTW = 0
[ 0.516984] Data abort info:
[ 0.517149] ISV = 0, ISS = 0x00000004
[ 0.517339] CM = 0, WnR = 0
[ 0.517553] [0000800074c12000] user address but active_mm is swapper
[ 0.517928] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[ 0.518305] Modules linked in:
[ 0.518839] CPU: 0 PID: 13 Comm: kdevtmpfs Not tainted 4.19.0-rc5-next-20180928-00002-g2ba39ab0cd01-dirty #82
[ 0.519307] Hardware name: linux,dummy-virt (DT)
[ 0.519681] pstate: 80000005 (Nzcv daif -PAN -UAO)
[ 0.519959] pc : __destroy_inode+0x94/0x2a8
[ 0.520212] lr : __destroy_inode+0x78/0x2a8
[ 0.520401] sp : ffff0000098c3b20
[ 0.520590] x29: ffff0000098c3b20 x28: 00000000087a3714
[ 0.520904] x27: 0000000000002000 x26: 0000000000002000
[ 0.521179] x25: ffff000009583000 x24: 0000000000000000
[ 0.521467] x23: ffff80007bb52000 x22: ffff80007bbaa7c0
[ 0.521737] x21: ffff0000093f9338 x20: 0000000000000000
[ 0.522033] x19: ffff80007bbb05d8 x18: 0000000000000400
[ 0.522376] x17: 0000000000000000 x16: 0000000000000000
[ 0.522727] x15: 0000000000000400 x14: 0000000000000400
[ 0.523068] x13: 0000000000000001 x12: 0000000000000001
[ 0.523421] x11: 0000000000000000 x10: 0000000000000970
[ 0.523749] x9 : ffff0000098c3a60 x8 : ffff80007bbab190
[ 0.524017] x7 : ffff80007bbaa880 x6 : 0000000000000c88
[ 0.524305] x5 : ffff0000093d96c8 x4 : 61c8864680b583eb
[ 0.524567] x3 : ffff0000093d6180 x2 : ffffffffffffffff
[ 0.524872] x1 : 0000800074c12000 x0 : 0000800074c12000
[ 0.525207] Process kdevtmpfs (pid: 13, stack limit = 0x(____ptrval____))
[ 0.525529] Call trace:
[ 0.525806] __destroy_inode+0x94/0x2a8
[ 0.526108] destroy_inode+0x34/0x88
[ 0.526370] evict+0x144/0x1c8
[ 0.526636] iput+0x184/0x230
[ 0.526871] dentry_unlink_inode+0x118/0x130
[ 0.527152] d_delete+0xd8/0xe0
[ 0.527420] vfs_unlink+0x240/0x270
[ 0.527665] handle_remove+0x1d8/0x330
[ 0.527875] devtmpfsd+0x138/0x1c8
[ 0.528085] kthread+0x14c/0x158
[ 0.528291] ret_from_fork+0x10/0x18
[ 0.528720] Code: 92800002 aa1403e0 d538d081 8b010000 (c85f7c04)
[ 0.529367] ---[ end trace 5a3dee47727f877c ]---
Rework to set suppress_bind_attrs flag to avoid removing the device when
CONFIG_DEBUG_TEST_DRIVER_REMOVE=y. This applies for pic32_uart and
xilinx_uartps as well.
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
Commit 9b96fbacda34 ("serial: PL011: clear pending interrupts")
clears the RX and receive timeout interrupts on pl011 startup, to
avoid a screaming-interrupt scenario that can occur when the
firmware or bootloader leaves these interrupts asserted.
This has been noted as an issue when running Linux on qemu [1].
Unfortunately, the above fix seems to lead to potential
misbehaviour if the RX FIFO interrupt is asserted _non_ spuriously
on driver startup, if the RX FIFO is also already full to the
trigger level.
Clearing the RX FIFO interrupt does not change the FIFO fill level.
In this scenario, because the interrupt is now clear and because
the FIFO is already full to the trigger level, no new assertion of
the RX FIFO interrupt can occur unless the FIFO is drained back
below the trigger level. This never occurs because the pl011
driver is waiting for an RX FIFO interrupt to tell it that there is
something to read, and does not read the FIFO at all until that
interrupt occurs.
Thus, simply clearing "spurious" interrupts on startup may be
misguided, since there is no way to be sure that the interrupts are
truly spurious, and things can go wrong if they are not.
This patch instead clears the interrupt condition by draining the
RX FIFO during UART startup, after clearing any potentially
spurious interrupt. This should ensure that an interrupt will
definitely be asserted if the RX FIFO subsequently becomes
sufficiently full.
The drain is done at the point of enabling interrupts only. This
means that it will occur any time the UART is newly opened through
the tty layer. It will not apply to polled-mode use of the UART by
kgdboc: since that scenario cannot use interrupts by design, this
should not matter. kgdboc will interact badly with "normal" use of
the UART in any case: this patch makes no attempt to paper over
such issues.
This patch does not attempt to address the case where the RX FIFO
fills faster than it can be drained: that is a pathological
hardware design problem that is beyond the scope of the driver to
work around. As a failsafe, the number of poll iterations for
draining the FIFO is limited to twice the FIFO size. This will
ensure that the kernel at least boots even if it is impossible to
drain the FIFO for some reason.
[1] [Qemu-devel] [Qemu-arm] [PATCH] pl011: do not put into fifo
before enabled the interruption
https://lists.gnu.org/archive/html/qemu-devel/2018-01/msg06446.html
Reported-by: Wei Xu <xuwei5@hisilicon.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>
Fixes: 9b96fbacda34 ("serial: PL011: clear pending interrupts")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: stable <stable@vger.kernel.org>
Tested-by: Wei Xu <xuwei5@hisilicon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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