When a serial port is used for kernel console output, then all
modifications to the UART registers which are done from other contexts,
e.g. getty, termios, are interference points for the kernel console.
So far this has been ignored and the printk output is based on the
principle of hope. The rework of the console infrastructure which aims to
support threaded and atomic consoles, requires to mark sections which
modify the UART registers as unsafe. This allows the atomic write function
to make informed decisions and eventually to restore operational state. It
also allows to prevent the regular UART code from modifying UART registers
while printk output is in progress.
All modifications of UART registers are guarded by the UART port lock,
which provides an obvious synchronization point with the console
infrastructure.
To avoid adding this functionality to all UART drivers, wrap the
spin_[un]lock*() invocations for uart_port::lock into helper functions
which just contain the spin_[un]lock*() invocations for now. In a
subsequent step these helpers will gain the console synchronization
mechanisms.
Converted with coccinelle. No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20230914183831.587273-41-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The DT of_device.h and of_platform.h date back to the separate
of_platform_bus_type before it as merged into the regular platform bus.
As part of that merge prepping Arm DT support 13 years ago, they
"temporarily" include each other. They also include platform_device.h
and of.h. As a result, there's a pretty much random mix of those include
files used throughout the tree. In order to detangle these headers and
replace the implicit includes with struct declarations, users need to
explicitly include the correct includes.
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # for imx
Link: https://lore.kernel.org/r/20230724205440.767071-1-robh@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Clang warns:
drivers/tty/serial/mps2-uart.c:351:6: warning: logical not is only
applied to the left hand side of this bitwise operator
[-Wlogical-not-parentheses]
if (!mps_port->flags & UART_PORT_COMBINED_IRQ) {
^ ~
drivers/tty/serial/mps2-uart.c:351:6: note: add parentheses after the
'!' to evaluate the bitwise operator first
if (!mps_port->flags & UART_PORT_COMBINED_IRQ) {
^
( )
drivers/tty/serial/mps2-uart.c:351:6: note: add parentheses around left
hand side expression to silence this warning
if (!mps_port->flags & UART_PORT_COMBINED_IRQ) {
^
( )
1 warning generated.
As it was intended for this check to be the inverse of the one at the
bottom of mps2_init_port, add parentheses around the whole conditional.
Fixes: 775ea4ea2f ("serial: mps2-uart: support combined irq")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Vladimir Murzin <vladimir.murzin@arm.com>
Link: https://github.com/ClangBuiltLinux/linux/issues/344
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It turns out that some designs went for implementing only combined
interrupt for rx, tx and overrun, which is currently not supported
by the driver. Support of combined irq is built on top of existent
irq handlers and activated automatically if only single irq was
specified in device tree.
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some designs, like MPS3, expose number of virtual serial ports which
already close or exceeds MPS2_MAX_PORTS. Increasing MPS2_MAX_PORTS
would have negative impact (in terms of memory consumption) on tiny
MPS2 platform which, in fact, has only one physically populated UART.
Start with converting existent static port array to idr. As a bonus it
make driver not to fail in case when no alias was specified in device
tree.
Note: there is no need in idr_destroy() because code doesn't unload
since ce87122911 ("serial: mps2-uart: make driver explicitly non-modular")
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The Kconfig currently controlling compilation of mps2-uart is:
config SERIAL_MPS2_UART
bool "MPS2 UART port"
depends on ARM || COMPILE_TEST
...meaning that it currently is not being built as a module by anyone.
Follow commit 89ebc27427 ("drivers/tty: make serial/mvebu-uart.c
explicitly non-modular") as an example of moving modular code to
non-modular:
- remove the modular code that is essentially orphaned, so that
when reading the driver there is no doubt it is builtin-only.
- explicitly disallow a driver unbind, since that doesn't have a
sensible use case anyway, and it allows us to drop the ".remove"
code for non-modular drivers.
- use arch_initcall instead of module_init and remove module_exit.
Also note that MODULE_DEVICE_TABLE is a no-op for non-modular code.
We also delete the MODULE_LICENSE tag etc. since all that information
was (or is now) contained at the top of the file in the comments.
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
