Switch character types to u8. To conform to characters in the rest of
the tty layer.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20231206073712.17776-7-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There are still last minor users in the tty core that still reference
characters by the 'char' type. Switch them to u8.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231206073712.17776-6-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty_operations::send_xchar is one of the last users of 'char' type for
characters in the tty layer. Convert it to u8 now.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Karsten Keil <isdn@linux-pingi.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: netdev@vger.kernel.org
Cc: linux-mmc@vger.kernel.org
Cc: linux-bluetooth@vger.kernel.org
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20231206073712.17776-5-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Both xmit_buf and xmit_fifo of struct tty_port should be u8. To conform
to characters in the rest of the tty layer.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231206073712.17776-4-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sdio_in() returns a value returned from sdio_readb(). The latter returns
u8. So should the former. Therefore, switch sdio_in() return type to u8
and all its callers too.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: linux-mmc@vger.kernel.org
Link: https://lore.kernel.org/r/20231206073712.17776-3-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

do_rw_io()'s is_write parameter is boolean, but typed int. Switch to the
former, so that it's obvious. (And the two users too.)
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231206073712.17776-2-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Parse the OPP table from the device tree and use dev_pm_opp_set_rate()
instead of clk_set_rate() to allow making performance state votes
specified in the OPP table (e.g. for power domains and interconnects).

Without an OPP table in the device tree this will behave just as before
this patch.
Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Link: https://lore.kernel.org/r/20231128-serial-msm-dvfs-v1-2-4f290d20a4be@kernkonzept.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Document power-domains, operating-points-v2 and interconnects to allow
making performance state votes for certain clock frequencies of the UART
DM controller. The interconnect path to DRAM is needed when UART DM is
used together with a DMA engine.

Voting for these shared resources is necessary to guarantee performance
with power management enabled. Otherwise these resources might run at
minimal performance state which is not sufficient for certain UART
baud rates.
Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20231128-serial-msm-dvfs-v1-1-4f290d20a4be@kernkonzept.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

sparse reports multiple problems with address space type.

Most problems are linked to missing __iomem qualifier.

Others are caused by dereferencing __iomem addresses.

Fix all this by adding missing __iomem and using ioread32be().
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312050412.zN2PKArS-lkp@intel.com/Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/e49deeb079391ff7273ec32f5563df94cf70bc95.1701781976.git.christophe.leroy@csgroup.euSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Refer ARM DDI 0487I.a ID081822, D17.3.8, DBGDTRTX_EL0,
"If TXfull is set to 1, set DTRRX and DTRTX to UNKNOWN"

Thus one should always check for TXfull condition before hvc can be
used as an early console. This is similar to what is being done
today in hvc_dcc_console_init() and hvc_dcc_init().

The count 0x4000000 has been obtained from uboot (v2024.01-rc3)
drivers/serial/arm_dcc.c "TIMEOUT_COUNT".
It reads the dcc status and waits for 0x4000000  times for the TX Fifo
to be available before returning an error. Thus, it will prevent DCC
to be used as early console.
Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
Link: https://lore.kernel.org/r/20231205123534.3376883-1-ayan.kumar.halder@amd.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The dw-apb-uart also can emulate rs485, so include the rs485
schema to allow validating rs485 properties.
Signed-off-by: Heiko Stuebner <heiko.stuebner@cherry.de>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20231201140542.323564-1-heiko@sntech.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fix whitespace in include/linux/amba/serial.h to match current kernel
coding standards. Fixes about:

 - CHECK: spaces preferred around that '|' (ctx:VxV)
 - ERROR: code indent should use tabs where possible
 - WARNING: Unnecessary space before function pointer arguments
 - WARNING: please, no spaces at the start of a line
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20231130-mbly-uart-v5-1-6566703a04b5@bootlin.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The last user of virtio_cons_early_init() was dropped in commit
7fb2b2d5 ("s390/virtio: remove the old KVM virtio transport").

So now, drop virtio_cons_early_init() and the logic and headers behind
too.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Acked-by: Jason Wang <jasowang@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Amit Shah <amit@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: linux-alpha@vger.kernel.org
Cc: virtualization@lists.linux.dev
Link: https://lore.kernel.org/r/20231130113001.29154-1-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When using the serial port as RS485 port, the tx statemachine is used to
control the RTS pin to drive the RS485 transceiver TX_EN pin. When the
TTY port is closed in the middle of a transmission (for instance during
userland application crash), imx_uart_shutdown disables the interface
and disables the Transmission Complete interrupt. afer that,
imx_uart_stop_tx bails on an incomplete transmission, to be retriggered
by the TC interrupt. This interrupt is disabled and therefore the tx
statemachine never transitions out of SEND. The statemachine is in
deadlock now, and the TX_EN remains low, making the interface useless.

imx_uart_stop_tx now checks for incomplete transmission AND whether TC
interrupts are enabled before bailing to be retriggered. This makes sure
the state machine handling is reached, and is properly set to
WAIT_AFTER_SEND.

Fixes: cb1a6092 ("serial: imx: implement rts delaying for rs485")
Signed-off-by: Paul Geurts <paul_geurts@live.nl>
Tested-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Tested-by: Eberhard Stoll <eberhard.stoll@gmx.de>
Link: https://lore.kernel.org/r/AM0PR09MB26758F651BC1B742EB45775995B8A@AM0PR09MB2675.eurprd09.prod.outlook.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Designware UART has an optional feature to enable Fractional Baud Rate
Divisor (DLF) through the FRACTIONAL_BAUD_DIVISOR_EN configuration
parameter, and it is not dependent on ADDITIONAL_FEATURES.

dw8250_setup_port() checks DLF to determine dlf_size only when UART
Component Version (UCV) is non-zero. As mentioned above DLF and UCV are
independent features. Move the logic corresponding to DLF size
calculation ahead of the UCV check to prevent early return. Otherwise,
dlf_size will be zero and driver will not be able to use the
controller's fractional baud rate divisor (DLF) feature.
Signed-off-by: Vamshi Gajjela <vamshigajjela@google.com>
Link: https://lore.kernel.org/r/20231126160420.2442330-1-vamshigajjela@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

'str_cr' contains a single character: \r. There is no need to declare it
as array. Instead, pass the character (as a string) to callback_puts()
directly. This ensures the string is in proper .rodata (const) section
and makes the code more obvious.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: linux-alpha@vger.kernel.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231127123713.14504-5-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

'need_cr' is a flag, so type it properly to be a 'bool'. Move the
declaration into the loop too. That ensures the variable is initialized
properly even if the code was moved somehow.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: linux-alpha@vger.kernel.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231127123713.14504-4-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Similarly to 'buf' in the previous patch, there is no need to have a
separate counter ('remaining') in srmcons_do_write(). 'count' can be
used directly which simplifies the code a bit.

Note that the type of the current count ('c') is changed from 'long' to
'size_t' so that:
1) it is prepared for the upcoming change of 'count's type, and
2) is unsigned.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: linux-alpha@vger.kernel.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231127123713.14504-3-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The return value of srmcons_do_write() is ignored as all characters are
pushed. So make srmcons_do_write() to return void.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: linux-alpha@vger.kernel.org
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231127123713.14504-2-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

After commit 87888fb9 ("tty: Remove baudrate dead code & make
ktermios params const"), the 'tty' parameter is only read in
tty_get_baud_rate(). Therefore, we can make 'tty' accepted in the
function 'const' for clarity.

The "the terminal bit flags may be updated." part of the
tty_get_baud_rate()'s kernel-doc is dropped as it is no longer true.
Because of the same commit above. And it was misplaced anyway.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231127123713.14504-1-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There is no need to have a separate iterator ('cur') through 'buf' in
srmcons_do_write(). 'buf' can be used directly which simplifies the code
a bit.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: linux-alpha@vger.kernel.org
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Link: https://lore.kernel.org/r/20231121092258.9334-14-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

DUMP()'s only use is commented out. Remove the macro completely along
with this unused use.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231121092258.9334-13-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This means:
* move outbuf to the end of struct hvc_struct and convert from pointer
  to flexible array (the structure is smaller now)
* use struct_size() at the allocation site
* align outbuf in the struct instead of ALIGN() at kzalloc()

And apart from the above, use u8 instead of char (which are the same
thanks to -funsigned-char). The former is now preferred over the latter.

It makes the code easier to understand.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20231121092258.9334-12-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

'serial_table' is global, so there is no need to initialize it to NULLs
at the module load. Drop this unneeded for loop.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-usb@vger.kernel.org
Cc: netdev@vger.kernel.org
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20231121092258.9334-11-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

It's preferred NOT to emit anything during the module load and unload
(in case the un/load was successful). So drop these prints from hso
along with global 'version'. It even contains no version after all.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: linux-usb@vger.kernel.org
Cc: netdev@vger.kernel.org
Acked-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20231121092258.9334-10-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

We can pass 'buf' directly to goldfish_tty_rw() using simple (unsigned
long) cast. There is no need to obfuscate the code by another variable
with double casts.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231121092258.9334-9-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

There is a helper for memcpy(buffer)+memset(the_rest). Use it for
simplicity.

And add a comment why we are doing the copy in the first place.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20231121092258.9334-8-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

'oe' is a yes-no flag, switch it to boolean. And rename to overrun. All
for the code to be more obvious.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231121092258.9334-7-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The 'out' label is just before 'return'. So return immediately and drop
both the label and the return. This makes the code more straightforward.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231121092258.9334-6-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Both tty_kref_get() and tty_get_baud_rate() note about locking in their
Return kernel-doc clause. Extract this info into a separate "Locking"
paragraph -- the same as we do for other tty functions.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Suggested-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20231121092258.9334-5-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

'mbz' in tiocsti() is used only to pass TTY_NORMAL to
tty_ldisc_ops::receive_buf(). But that can be achieved easier by simply
passing NULL to ::receive_buf().

So drop this 'mbz'.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231121092258.9334-3-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

tty_write_message() has only one user: quotas. In particular, there the
use depends on CONFIG_PRINT_QUOTA_WARNING. And that is deprecated and
marked as BROKEN already too.

So make tty_write_message() dependent on that very config option. This
action in fact drops tty_write_message() from the vmlinux binary. Good
riddance.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Jan Kara <jack@suse.com>
Acked-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20231121092258.9334-2-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Commits 95713967 ("tty: make tty_operations::write()'s count
size_t") and dcaafbe6 ("tty: propagate u8 data to
tty_operations::put_char()") changed types of characters to u8, but
omitted to fix the documentation.

Fix the latter now.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231121092258.9334-4-jirislaby@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The comment wording can be confusing, as txlen will return the number of
bytes available in the FIFO, which can be less than the maximum theoretical
Tx FIFO size.

Change the comment so that it is unambiguous.
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231122175957.3875102-1-hugo@hugovil.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The comment wording can be confusing, as txlen will return the number of
bytes available in the FIFO, which can be less than the maximum theoretical
Tx FIFO size.

Change the comment so that it is unambiguous.
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231122175859.3874753-1-hugo@hugovil.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 81a61051.

With tty and serdev controller moved to be children of the serial core
port device, runtime PM usage count of the serdev controller now
propagates to the serial hardware controller parent device as expected.

Cc: Maximilian Luz <luzmaximilian@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231113080758.30346-2-tony@atomide.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Let's move tty and serdev controller to be children of the serial core port
device. This way the runtime PM usage count of a child device propagates
to the serial hardware device.

The tty and serdev devices are associated with a specific serial port of
a serial hardware controller device, and we now have serial core hierarchy
of controllers and ports.

The tty device moves happily with just a change of the parent device and
update of device_find_child() handling. The serdev device init needs some
changes to separate the serial hardware controller device from the parent
device.

With this change the tty devices move under sysfs similar to this x86_64
qemu example of a diff of "find /sys -name ttyS*":

 /sys/class/tty/ttyS0
 /sys/class/tty/ttyS3
 /sys/class/tty/ttyS1
-/sys/devices/pnp0/00:04/tty/ttyS0
-/sys/devices/platform/serial8250/tty/ttyS2
-/sys/devices/platform/serial8250/tty/ttyS3
-/sys/devices/platform/serial8250/tty/ttyS1
+/sys/devices/pnp0/00:04/00:04:0/00:04:0.0/tty/ttyS0
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.3/tty/ttyS3
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.1/tty/ttyS1
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.2/tty/ttyS2

If a serdev device is used instead of a tty, it moves in a similar way.
Suggested-by: Johan Hovold <johan@kernel.org>
Cc: Maximilian Luz <luzmaximilian@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20231113080758.30346-1-tony@atomide.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This way we can do:
`echo _reisub > /proc/sysrq-trigger`
Instead of:
`for i in r e i s u b; do echo "$i" > /proc/sysrq-trigger; done;`

This can be very useful when trying to execute sysrq combo remotely
or from userspace. When sending keys in multiple separate writes,
userspace (eg. bash or ssh) can be killed before whole combo is completed.
Therefore putting all keys in single write is more robust approach.
Signed-off-by: Tomas Mudrunka <tomas.mudrunka@gmail.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20231120111451.527952-1-tomas.mudrunka@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Device number 204 has a range of minors on major number.
uart_register_driver is failing due to lack of minor numbers
when more number of uart ports used. So, to avoid minor number
limitation on 204 major number use dynamic major allocation
when more than 4 uart ports used otherwise use static major
allocation.

https://docs.kernel.org/arch/arm/sa1100/serial_uart.htmlSigned-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
Link: https://lore.kernel.org/r/20231116134003.3762725-3-manikanta.guntupalli@amd.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Describe when uartlite driver uses static/dynamic allocation for major
number based on maximum number of uartlite serial ports.
Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@amd.com>
Link: https://lore.kernel.org/r/20231116134003.3762725-2-manikanta.guntupalli@amd.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>