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>
The macro "spi_register_driver" invokes the function
"__spi_register_driver()" which has a return type of int and can fail,
returning a negative value in such a case. This is currently ignored and
the init() function yields success even if the spi driver failed to
register.
Fix this by collecting the return value of "__spi_register_driver()" and
also unregister the uart driver in case of failure.
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Atul Gopinathan <atulgopinathan@gmail.com>
Link: https://lore.kernel.org/r/20210503115736.2104747-12-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 51f689cc11.
Because of recent interactions with developers from @umn.edu, all
commits from them have been recently re-reviewed to ensure if they were
correct or not.
Upon review, this commit was found to be incorrect for the reasons
below, so it must be reverted. It will be fixed up "correctly" in a
later kernel change.
This change did not properly unwind from the error condition, so it was
not correct.
Cc: Kangjie Lu <kjlu@umn.edu>
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20210503115736.2104747-11-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 32f4717983.
Because of recent interactions with developers from @umn.edu, all
commits from them have been recently re-reviewed to ensure if they were
correct or not.
Upon review, this commit was found to be not be needed at all as the
change was useless because this function can only be called when
of_match_device matched on something. So it should be reverted.
Cc: Aditya Pakki <pakki001@umn.edu>
Cc: stable <stable@vger.kernel.org>
Fixes: 32f4717983 ("serial: mvebu-uart: Fix to avoid a potential NULL pointer dereference")
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20210503115736.2104747-6-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Receive FIFO Data Count Trigger field (RTRG[6:0]) in the Receive
FIFO Data Count Trigger Register (HSRTRGR) of HSCIF can only hold values
ranging from 0-127. As the FIFO size is equal to 128 on HSCIF, the user
can write an out-of-range value, touching reserved bits.
Fix this by limiting the trigger value to the FIFO size minus one.
Reverse the order of the checks, to avoid rx_trig becoming zero if the
FIFO size is one.
Note that this change has no impact on other SCIF variants, as their
maximum supported trigger value is lower than the FIFO size anyway, and
the code below takes care of enforcing these limits.
Fixes: a380ed461f ("serial: sh-sci: implement FIFO threshold register setting")
Reported-by: Linh Phung <linh.phung.jy@renesas.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/5eff320aef92ffb33d00e57979fd3603bbb4a70f.1620648218.git.geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit that added this check did so in a very strange way - first
security_locked_down() is called, its value stored into retval, and if
it's nonzero, then an additional check is made for (change_irq ||
change_port), and if this is true, the function returns. However, if
the goto exit branch is not taken, the code keeps the retval value and
continues executing the function. Then, depending on whether
uport->ops->verify_port is set, the retval value may or may not be reset
to zero and eventually the error value from security_locked_down() may
abort the function a few lines below.
I will go out on a limb and assume that this isn't the intended behavior
and that an error value from security_locked_down() was supposed to
abort the function only in case (change_irq || change_port) is true.
Note that security_locked_down() should be called last in any series of
checks, since the SELinux implementation of this hook will do a check
against the policy and generate an audit record in case of denial. If
the operation was to carry on after calling security_locked_down(), then
the SELinux denial record would be bogus.
See commit 59438b4647 ("security,lockdown,selinux: implement SELinux
lockdown") for how SELinux implements this hook.
Fixes: 794edf30ee ("lockdown: Lock down TIOCSSERIAL")
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210507115719.140799-1-omosnace@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Group the flow flags under a single struct called flow. The new struct
contains 'stopped' and 'tco_stopped' bools which used to be bits in a
bitfield. The struct also contains the lock protecting them to
potentially share the same cache line.
Note that commit c545b66c69 (tty: Serialize tcflow() with other tty
flow control changes) added a padding to the original bitfield. It was
for the bitfield to occupy a whole 64b word to avoid interferring stores
on Alpha (cannot we evaporate this arch with weird implications to C
code yet?). But it doesn't work as expected as the padding
(tty_struct::unused) is aligned to a 8B boundary too and occupies some
bytes from the next word.
So make it reliable by:
1) setting __aligned of the struct -- that aligns the start, and
2) making 'unsigned long unused[0]' as the last member of the struct --
pads the end.
This is also the perfect time to start the documentation of tty_struct
where all this lives. So we start by documenting what these bools
actually serve for. And why we do all the alignment dances. Only the few
up-to-date information from the Theodore's comment made it into this new
Kerneldoc comment.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/20210505091928.22010-13-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Our SoC's have always had a NS16650A UART core and older SoC's would
have a compatible string of: 'compatible = ""ns16550a"' and use the
8250_of driver. Our newer SoC's have added enhancements to the base
core to add support for DMA and accurate high speed baud rates and use
this newer 8250_bcm7271 driver. The Device Tree node for our enhanced
UARTs has a compatible string of: 'compatible = "brcm,bcm7271-uart",
"ns16550a"''. With both drivers running and the link order setup so
that the 8250_bcm7217 driver is initialized before the 8250_of driver,
we should bind the 8250_bcm7271 driver to the enhanced UART, or for
upstream kernels that don't have the 8250_bcm7271 driver, we bind to
the 8250_of driver.
The problem is that when both the 8250_of and 8250_bcm7271 drivers
were running, occasionally the 8250_of driver would be bound to the
enhanced UART instead of the 8250_bcm7271 driver. This was happening
because we use SCMI based clocks which come up late in initialization
and cause probe DEFER's when the two drivers get their clocks.
Occasionally the SCMI clock would become ready between the 8250_bcm7271
probe and the 8250_of probe and the 8250_of driver would be bound. To
fix this we decided to config only our 8250_bcm7271 driver and added
"ns16665a0" to the compatible string so the driver would work on our
older system.
This commit has of_platform_serial_probe() check specifically for the
"brcm,bcm7271-uart" and whether its companion driver is enabled. If it
is the case, and the clock provider is not ready, we want to make sure
that when the 8250_bcm7271.c driver returns EPROBE_DEFER, we are not
getting the UART registered via 8250_of.c.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jim Quinlan <jim2101024@gmail.com>
Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20210423183206.3917725-1-f.fainelli@gmail.com
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>
