Add the necessary driver boilerplate to let the driver be used when
the respective ACPI table is discovered by the ACPI subsystem.
[Andre: change table name, add MODULE_DEVICE_TABLE entry and improve
commit message]
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Graeme Gregory <graeme.gregory@linaro.org>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The ARM Server Base System Architecture[1] document describes a
generic UART which is a subset of the PL011 UART.
It lacks DMA support, baud rate control and modem status line
control, among other things.
The idea is to move the UART initialization and setup into the
firmware (which does this job today already) and let the kernel just
use the UART for sending and receiving characters.
We use the recent refactoring to build a new struct uart_ops
variable which points to some new functions avoiding access to the
missing registers. We reuse as much existing PL011 code as possible.
In contrast to the PL011 the SBSA UART does not define any AMBA or
PrimeCell relations, so we go with a pretty generic probe function
which only uses platform device functions.
A DT binding is provided with this patch, ACPI support is added in a
separate one.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The SBSA UART has a fixed baud rate and flow control setting, which
cannot be changed or queried by software.
Add a vendor specific property to always return fixed values when
trying to read the console options.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The SBSA UART should not be enabled or disabled (it is always on),
and consequently the spec lacks the UART_CR register.
Add a vendor specific property to skip disabling or enabling of the
UART. This will be used later by the SBSA UART support.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To avoid lines with more than 80 characters and to make the
pl011_int() function more readable, move the workaround out into a
separate function.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The PL011 register UART_MIS is actually a bitwise AND of the
UART_RIS and the UART_MISC register.
Since the SBSA UART does not include the _MIS register, use the
two separate registers to get the same behaviour. Since we are
inside the spinlock and we read the _IMSC register only once, there
should be no race issue.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently the pl011_probe() function is relying on some AMBA IDs
and a device tree node to initialize the driver and a port.
Both features are not necessarily required for the driver:
- we lack AMBA IDs in the ARM SBSA generic UART and
- we lack a DT node in ACPI systems.
So lets refactor the function to ease later reuse.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Split the pl011_set_termios() function into smaller chunks to allow
easier reuse later when adding SBSA support.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Split the pl011_shutdown() function into smaller chunks to allow
easier reuse later when adding SBSA support.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Split the pl011_startup() function into smaller chunks to allow
easier reuse later when adding SBSA support.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Although we care about not unregistering the driver if there are
still ports connected during the .remove callback, we do miss this
check in the pl011_probe function. So if the current port allocation
fails, but there are other ports already registered, we will kill
those.
So factor out the port removal into a separate function and use that
in the probe function, too.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If the mediatek serial port driver is built-in, but serial
console is disabled in Kconfig (e.g. when the serial driver
itself is a loadable module), we get this build error:
drivers/built-in.o: In function `early_mtk8250_setup':
undefined reference to `early_serial8250_setup'
To avoid that problem, this patch encloses the early_mtk8250_setup
function in #ifdef CONFIG_SERIAL_8250_CONSOLE, the same symbol
that guards the early_serial8250_setup function.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Eddie Huang <eddie.huang@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A configuration that enables earlycon but not the core console
code causes a link error:
drivers/built-in.o: In function `setup_earlycon':
drivers/tty/serial/earlycon.c:70: undefined reference to `uart_parse_earlycon'
That error can be triggered by the newly added samsung earlycon support,
which is missing a 'select' statement.
As suggested by Peter Hurley, solves the problem by moving the
'select SERIAL_EARLYCON' statement to the samsung console driver
option, as it is done by all other console drivers.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: b94ba0328d ("serial: samsung: Add support for early console")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The platform_sysrq_reset_seq code was intended as a way for an embedded
platform to provide its own sysrq sequence at compile time. After over
two years, nobody has started using it in an upstream kernel, and
the platforms that were interested in it have moved on to devicetree,
which can be used to configure the sequence without requiring kernel
changes. The method is also incompatible with the way that most
architectures build support for multiple platforms into a single
kernel.
Now the code is producing warnings when built with gcc-5.1:
drivers/tty/sysrq.c: In function 'sysrq_init':
drivers/tty/sysrq.c:959:33: warning: array subscript is above array bounds [-Warray-bounds]
key = platform_sysrq_reset_seq[i];
We could fix this, but it seems unlikely that it will ever be used,
so let's just remove the code instead. We still have the option to
pass the sequence either in DT, using the kernel command line,
or using the /sys/module/sysrq/parameters/reset_seq file.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 154b7a489a ("Input: sysrq - allow specifying alternate reset sequence")
----
v2: moved sysrq_reset_downtime_ms variable to avoid introducing a compile
warning when CONFIG_INPUT is disabled
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The function mctrl_gpio_init returns failure if the assignment to any
member of the gpio array results in an error pointer. So there is no
need to check for such error values in the other functions.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The currently in-use port->startup and port->shutdown are "okay". The
startup part for instance does the tiny omap extra part and invokes
serial8250_do_startup() for the remaining pieces. The workflow in
serial8250_do_startup() is okay except for the part where UART_RX is
read without a check if there is something to read. I tried to
workaround it in commit 0aa525d118 ("tty: serial: 8250_core: read only
RX if there is something in the FIFO") but then reverted it later in
commit ca8bb4aefb ("serial: 8250: Revert "tty: serial: 8250_core: read
only RX if there is something in the FIFO"").
This is the second attempt to get it to work on older OMAPs without
breaking other chips this time
Peter Hurley suggested to pull in the few needed lines from
serial8250_do_startup() and drop everything else that is not required
including making it simpler like using just request_irq() instead the
chain handler like it is doing now.
So lets try that.
Fixes: ca8bb4aefb ("serial: 8250: Revert "tty: serial: 8250_core:
read only RX if there is something in the FIFO"")
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If the call to dmaengine_slave_config() fails, then the DMA buffer will
not be freed/unmapped. Fix this by moving the code that stores the
address of the buffer in the tegra_uart_port structure to before the
call to dmaengine_slave_config().
Reported-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
it seems this is a more typical behaviour from reviewing other console
drivers.
Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
add overrun error's flag mark and parity's counter, we can show the
statistic from procfs node.
BTW, let the indentation of stick bits configuration look better.
Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In special condition, when cpu schedule into rx_tmo_process_tl or
rx_dma_complete_tl and all the receive dma tasks have done, it will
go into endless loop because no dma task cookie status be changed.
Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>From HW spec, when rxfifo's data is less than AFC_RX_THD(RX threshhold), RTS
signal is active. otherwise, RTS signal is inactive.
Crrently the RX threshhold is set as zero, so RTS has no chance to be
active. This patch replaces the default 0 by a positive number.
Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
differentiate difference port types by re-defining the status MARCO
or putting HW differences into private data of the related ports.
Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This comment does not reflect the actual code. It should be 57600,
not 56000.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In RS485 mode, we may want to set the delay_rts_after_send value to 0.
In the datasheet, the 0 value is said to "disable" the Transmitter Timeguard but
this is exactly the expected behavior if we want no delay...
Moreover, if the value was set to non-zero value by device-tree or earlier
ioctl command, it was impossible to change it back to zero.
Reported-by: Sami Pietikäinen <Sami.Pietikainen@wapice.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable@vger.kernel.org # 3.2+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In commit 02730d3c05
(Merge 4.1-rc4 into tty-next), git mismerged some lines,
reintroducing a reference to the removed field
uart_amba_port.tx_irq_seen. This causes a build failure.
This patch removes the mismerged lines, restoring the code to what
was in tty-next (which was the intention).
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here's some TTY and serial driver fixes for reported issues. All of
these have been in linux-next successfully.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial fixes from Greg KH:
"Here's some TTY and serial driver fixes for reported issues.
All of these have been in linux-next successfully"
* tag 'tty-4.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
pty: Fix input race when closing
tty/n_gsm.c: fix a memory leak when gsmtty is removed
Revert "serial/amba-pl011: Leave the TX IRQ alone when the UART is not open"
serial: omap: Fix error handling in probe
earlycon: Revert log warnings
This was introduced in
commit 6db4063c5b
Author: Antonino A. Daplas <adaplas@gmail.com>
Date: Mon Jun 26 00:27:12 2006 -0700
[PATCH] VT binding: Add sysfs control to the VT layer
with the justification
"In addition, if any of the consoles are in KD_GRAPHICS mode, binding and
unbinding will not succeed. KD_GRAPHICS mode usually indicates that the
underlying console hardware is used for other purposes other than displaying
text (ie X). This feature should prevent binding/unbinding from interfering
with a graphics application using the VT."
I think we should lift this artificial restriction though:
- KD_GRAPHICS doesn't get cleaned up automatically, which means it's
easy to have terminals stuck in KD_GRAPHICS when hacking around on
X.
- X doesn't really care, especially with drm where kms already blocks
fbdev (and hence fbcon) when there's an active compositor.
- This is a root-only interface with a separate .config option and
it's possible to hang your machine already anyway if you
unload/reload drivers and don't know what you're doing.
With this patch i915.ko module reloading works again reliably,
something in the recent fedora upgrades broke things.
Cc: Antonino A. Daplas <adaplas@gmail.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Imre Deak <imre.deak@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Acked-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Currently there is a lock order problem between the console lock and the
kernfs s_active lock of the console driver's bind sysfs entry. When
writing to the sysfs entry the lock order is first s_active then console
lock, when unregistering the console driver via
do_unregister_con_driver() the order is the opposite. See the below
bugzilla reference for one instance of a lockdep backtrace.
Fix this by unregistering the console driver from a deferred work, where
we can safely drop the console lock while unregistering the device and
corresponding sysfs entries (which in turn acquire s_active). Note that
we have to keep the console driver slot in the registered_con_driver
array reserved for the driver that's being unregistered until it's fully
removed. Otherwise a concurrent call to do_register_con_driver could
try to reuse the same slot and fail when registering the corresponding
device with a minor index that's still in use.
Note that the referenced bug report contains two dmesg logs with two
distinct lockdep reports: [1] is about a locking scenario involving
s_active, console_lock and the fb_notifier list lock, while [2] is
about a locking scenario involving only s_active and console_lock.
In [1] locking fb_notifier triggers the lockdep warning only because
of its dependence on console_lock, otherwise case [1] is the same
s_active<->console_lock dependency problem fixed by this patch.
Before this change we have the following locking scenarios involving
the 3 locks:
a) via do_unregister_framebuffer()->...->do_unregister_con_driver():
1. console lock 2. fb_notifier lock 3. s_active lock
b) for example via give_up_console()->do_unregister_con_driver():
1. console lock 2. s_active lock
c) via vt_bind()/vt_unbind():
1. s_active lock 2. console lock
Since c) is the console bind sysfs entry's write code path we can't
change the locking order there. We can only fix this issue by removing
s_active's dependence on the other two locks in a) and b). We can do
this only in the vt code which owns the corresponding sysfs entry, so
that after the change we have:
a) 1. console lock 2. fb_notifier lock
b) 1. console lock
c) 1. s_active lock 2. console lock
d) in the new con_driver_unregister_callback():
1. s_active lock
[1] https://bugs.freedesktop.org/attachment.cgi?id=87716
[2] https://bugs.freedesktop.org/attachment.cgi?id=107602
v2:
- get console_lock earlier in con_driver_unregister_callback(), so we
protect the following console driver field assignments there
- add code coment explaining the reason for deferring the sysfs entry
removal
- add a third paragraph to the commit message explaining why there are
two distinct lockdep reports and that this issue is independent of
fb/fbcon. (Peter Hurley)
v3:
- clarify further the third paragraph
v4:
- rebased on v4 of patch 1/3
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A read() from a pty master may mistakenly indicate EOF (errno == -EIO)
after the pty slave has closed, even though input data remains to be read.
For example,
pty slave | input worker | pty master
| |
| | n_tty_read()
pty_write() | | input avail? no
add data | | sleep
schedule worker --->| | .
|---> flush_to_ldisc() | .
pty_close() | fill read buffer | .
wait for worker | wakeup reader --->| .
| read buffer full? |---> input avail ? yes
|<--- yes - exit worker | copy 4096 bytes to user
TTY_OTHER_CLOSED <---| |<--- kick worker
| |
**** New read() before worker starts ****
| | n_tty_read()
| | input avail? no
| | TTY_OTHER_CLOSED? yes
| | return -EIO
Several conditions are required to trigger this race:
1. the ldisc read buffer must become full so the input worker exits
2. the read() count parameter must be >= 4096 so the ldisc read buffer
is empty
3. the subsequent read() occurs before the kicked worker has processed
more input
However, the underlying cause of the race is that data is pipelined, while
tty state is not; ie., data already written by the pty slave end is not
yet visible to the pty master end, but state changes by the pty slave end
are visible to the pty master end immediately.
Pipeline the TTY_OTHER_CLOSED state through input worker to the reader.
1. Introduce TTY_OTHER_DONE which is set by the input worker when
TTY_OTHER_CLOSED is set and either the input buffers are flushed or
input processing has completed. Readers/polls are woken when
TTY_OTHER_DONE is set.
2. Reader/poll checks TTY_OTHER_DONE instead of TTY_OTHER_CLOSED.
3. A new input worker is started from pty_close() after setting
TTY_OTHER_CLOSED, which ensures the TTY_OTHER_DONE state will be
set if the last input worker is already finished (or just about to
exit).
Remove tty_flush_to_ldisc(); no in-tree callers.
Fixes: 52bce7f8d4 ("pty, n_tty: Simplify input processing on final close")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=96311
BugLink: http://bugs.launchpad.net/bugs/1429756
Cc: <stable@vger.kernel.org> # 3.19+
Reported-by: Andy Whitcroft <apw@canonical.com>
Reported-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
when gsmtty_remove put dlci, it will cause memory leak if dlci->port's refcount is zero.
So we do the cleanup work in .cleanup callback instead.
dlci will be last put in two call chains.
1) gsmld_close -> gsm_cleanup_mux -> gsm_dlci_release -> dlci_put
2) gsmld_remove -> dlci_put
so there is a race. the memory leak depends on the race.
In call chain 2. we hit the memory leak. below comment tells.
release_tty -> tty_driver_remove_tty -> gsmtty_remove -> dlci_put -> tty_port_destructor (WARN_ON(port->itty) and return directly)
|
tty->port->itty = NULL;
|
tty_kref_put ---> release_one_tty -> gsmtty_cleanup (added by our patch)
So our patch fix the memory leak by doing the cleanup work after tty core did.
Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
Fixes: dfabf7ffa3
Cc: stable <stable@vger.kernel.org> # 3.14+
Acked-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The beat hvc driver is only used by celleb.
celleb has been dropped [1], so drop the drivers.
[1] http://patchwork.ozlabs.org/patch/451730/
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Jiri Slaby <jslaby@suse.cz>
CC: Valentin Rothberg <valentinrothberg@gmail.com>
CC: mpe@ellerman.id.au
CC: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The CONFIG_ prefix is reserved for Kconfig options in Make and CPP
syntax. CONFIG_MAGIC is a file local CPP identifier so change the
prefix to apply to Kconfig's naming convention.
Signed-off-by: Valentin Rothberg <valentinrothberg@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This code is no longer used now that mach-msm has been removed.
Delete it.
Cc: David Brown <davidb@codeaurora.org>
Cc: Bryan Huntsman <bryanh@codeaurora.org>
Cc: Daniel Walker <dwalker@fifo99.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add an escape sequence to specify the current console's cursor blink
interval. The interval is specified as a number of milliseconds until
the next cursor display state toggle, from 50 to 65535. /proc/loadavg
did not show a difference with a one msec interval, but the lower
bound is set to 50 msecs since slower hardware wasn't tested.
Store the interval in the vc_data structure for later access by fbcon,
initializing the value to fbcon's current hardcoded value of 200 msecs.
Signed-off-by: Scot Doyle <lkml14@scotdoyle.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Function tegra_uart_dma_channel_allocate() does not check that
dma_map_single() mapped the DMA buffer correctly. Add a check for this
and appropriate error handling.
Furthermore, if dmaengine_slave_config() (called by
tegra_uart_dma_channel_allocate()) fails, then memory allocated/mapped
is not freed/unmapped. Therefore, call tegra_uart_dma_channel_free()
instead of just dma_release_channel() if dmaengine_slave_config() fails.
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are two issues in the shutdown path of the UARTs which are:
1. The function tegra_uart_shutdown() calls tegra_uart_flush_buffer()
to stop DMA TX transfers. However, tegra_uart_flush_buffer() is
called after the DMA channels have already been freed and so actually
does nothing.
2. The function that frees the DMA channels
(tegra_uart_dma_channel_free()), unmaps the dma buffer before
freeing the DMA channel and does not ensure the DMA has been
stopped.
Resolve this by fixing the code in tegra_uart_dma_channel_free() to
ensure the DMA is stopped, free the DMA channel and then unmap the DMA
buffer. Finally, remove the unnecessary call to tegra_uart_flush_buffer().
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The DMA cookie for the RX channel is being used by the TX channel.
Therefore, fix driver to use the correct DMA cookie for the TX channel.
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The function tty_insert_flip_string() takes an argument "size" which is
of type size_t. This is an unsigned type. Update the count,
rx_bytes_requested and tx_bytes_requested in the tegra serial driver to
be unsigned integers so that an unsigned type is passed to
tty_insert_flip_string().
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The tegra serial driver has two paths through which receive data is
copied up to the tty layer. These are:
1. DMA completion callback
2. UART RX interrupt
A UART RX interrupt occurs for either RX_TIMEOUT (data has been sitting
in the Rx FIFO for more than 4 character times without being read
because there is not enough data to reach the trigger level), End of
Receive Data event (receiver detects that data stops coming in for more
than 4 character times) or a receive error.
In the RX interrupt path, the following happens ...
- All RX DMA transfers are stopped
- Any data in the DMA buffer and RX FIFO are copied up to the tty layer.
- DMA is restarted/primed for the RX path
In the DMA completion callback, the DMA buffer is copied up to the tty
layer but there is no check to see if the RX interrupt could have
occurred between the DMA interrupt firing the the DMA callback running.
Hence, if a RX interrupt was to occur shortly after the DMA completion
interrupt, it is possible that the RX interrupt path has already copied
the DMA buffer before the DMA callback has been called. Therefore, when
the DMA callback is called, if the DMA is already in-progress, then this
indicates that the UART RX interrupt has already occurred and there is
nothing to do in the DMA callback. This race condition can cause
duplicated data to be received.
Signed-off-by: Shardar Shariff Md <smohammed@nvidia.com>
[jonathanh@nvidia.com: Moved async_tx_ack() call to after check to see
if DMA has completed because if the DMA is in progress we do not need
to ACK yet. Changed the print from dev_info to dev_debug. Updated
changelog to add more commentary on the race condition based upon
feedback from author.]
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It is only necessary to read data from the dma buffer when the count
value is non-zero and hence, tegra_uart_copy_rx_to_tty() so only be
called when this is the case.
Although, this was being tested for in two places, there is a third
place where this was not tested. However, instead of adding another
if-statement prior to calling tegra_uart_copy_rx_to_tty(), move the test
inside the function.
Signed-off-by: Shardar Shariff Md <smohammed@nvidia.com>
[jonathanh@nvidia.com: Re-worked patch to move the check for the count
value inside the function tegra_uart_copy_rx_to_tty(). Updated
changelog with more commentary.]
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
For all tegra devices (up to t210), there is a hardware issue that
requires software to wait for 3 UART clock periods after enabling
the TX fifo, otherwise data could be lost.
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
For all tegra devices (up to t210), there is a hardware issue that
requires software to wait for 32 UART clock periods for the flush
to propagate otherwise TX data could be post. Add a helper function
to wait for N UART clock periods and update delay following FIFO
flush to be 32 UART clock cycles.
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The port.type has already been set by of_platform_serial_setup()
called from a few lines above.
Setting it to the same value is redundant.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The port.fifosize member has already been copied at 8 lines above.
Maybe the compiler optimization can clean it away, but just in case.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Early console functions are only used during the early boot stage.
This change just saves a small amount of memory footprint.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When nr_uarts was set to 0 (via config or 8250_core.nr_uarts), we crash
early on x86 because serial8250_isa_init_ports dereferences base_ops
which remains NULL. In fact, there is nothing to do for all the callers
of serial8250_isa_init_ports if there are no uarts.
Based on suggestions by Peter Hurley.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The platform_device_id is not modified by the driver and core uses it as
const.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Graeme Gregory