On (H)SCIF with a Baud Rate Generator for External Clock (BRG), there
are multiple ways to configure the requested serial speed. If firmware
uses a different method than Linux, and if any debug info is printed
after the Bit Rate Register (SCBRR) is restored, but before termios is
reconfigured (which configures the alternative method), the system may
lock-up during resume.
Fix this by saving and restoring the contents of the BRG Frequency
Division (SCDL) and Clock Select (SCCKS) registers as well.
Also save and restore the HSCIF's Sampling Rate Register (HSSRR), which
configures the sampling point, and the SCIFA/SCIFB's Serial Port Control
and Data Registers (SCPCR/SCPDR), which configure the optional control
flow signals.
After this, all registers that are not saved/restored are either:
- read-only,
- write-only,
- status registers containing flags with clear-after-set semantics,
- FIFO Data Count Trigger registers, which do not matter much for
the serial console.
Fixes: 22a6984c5b ("serial: sh-sci: Update the suspend/resume support")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://lore.kernel.org/r/11c2eab45d48211e75d8b8202cce60400880fe55.1741114989.git.geert+renesas@glider.be
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Building with W=1 shows a warning about sbsa_uart_of_match being unused when
CONFIG_OF is disabled:
drivers/tty/serial/amba-pl011.c:2945:34: error: unused variable 'sbsa_uart_of_match' [-Werror,-Wunused-const-variable]
The driver is not actually used on any machines that are built
with CONFIG_OF disabled, so using of_match_ptr() won't save any
actual memory, and it can be best removed.
The corresponding ACPI_PTR() annotation does save a few bytes on
32-bit arm since CONFIG_ACPI is not available, but for consistency
it seems better to remove both along with the __maybe_unused
annotation on the ACPI table.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20250225163556.4169086-1-arnd@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
No need to overwrite the whole UARTMODIR register before waiting the
transmit engine complete, actually our target here is only to disable
CTS flow control to avoid the dirty data in TX FIFO may block the
transmit engine complete.
Also delete the following duplicate CTS disable configuration.
Fixes: d5a2e08343 ("tty: serial: lpuart: disable flow control while waiting for the transmit engine to complete")
Cc: stable <stable@kernel.org>
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20250307065446.1122482-1-sherry.sun@nxp.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
These ioctls are undocumented and not exposed -- they are defined
locally. Given they need a special tty_port just for them, this is very
ugly. So drop this whole functionality. It is barely used for something
real. (And if it is, we'd need a common functionality to all drivers.)
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-21-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Convert TTY_DRIVER_TYPE_*, and subtype macros to two enums:
tty_driver_type and tty_driver_subtype. This allows for easier
kernel-doc (later), grouping of these nicely, and proper checking.
The tty_driver's ::type and ::subtype now use these enums instead of
bare "short".
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-16-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
__tty_alloc_driver()'s kernel-doc needed some care: describe the return
value using the standard "Returns:", and use the new enum tty_driver_flag
for @flags.
Then, the tty_alloc_driver() macro was undocumented, but referenced many
times in the docs. Copy the docs from the above (except the @owner
parameter, obviously).
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-15-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Convert TTY_DRIVER_* macros (flags) to an enum. This allows for easier
kernel-doc (the comment needed fine tuning), grouping of these nicely,
and proper checking.
Given these are flags, define them using modern BIT() instead of hex
constants.
It turns out (thanks, kernel-doc checker) that internal
TTY_DRIVER_INSTALLED was undocumented. Fix that too.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-14-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
n_tty_read() contains "we need more data" handling deep in that
function. And there is also a label (more_to_be_read) as we handle this
situation from two places.
It makes more sense to have all "return"s accumulated at the end of
functions. And "goto" from multiple places there. Therefore, do this
with the "more_to_be_read" label in n_tty_read().
After this and the previous changes, n_tty_read() is now much more
easier to follow.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-12-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Use guard(mutex), which results in:
- the function can return directly when "space == 0".
- "i" can now be "unsigned" as it is no longer abused to hold a retval
from tty->ops->write(). Note the compared-to "nr" is already
"unsigned".
* The end label is now dubbed "do_write" as that is what happens there.
Unlike the uncertain "break_out" name.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-8-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty_write_room() returns an "unsigned int". So in case some insane
driver (like my tty test driver) returns (legitimate) UINT_MAX from its
tty_operations::write_room(), n_tty is confused on several places.
For example, in process_output_block(), the result of tty_write_room()
is stored into (signed) "int". So this UINT_MAX suddenly becomes -1. And
that is extended to ssize_t and returned from process_output_block().
This causes a write() to such a node to receive -EPERM (which is -1).
Fix that by using proper "unsigned int" and proper "== 0" test. And
return 0 constant directly in that "if", so that it is immediately clear
what is returned ("space" equals to 0 at that point).
Similarly for process_output() and __process_echoes().
Note this does not fix any in-tree driver as of now.
If you want "Fixes: something", it would be commit 03b3b1a240 ("tty:
make tty_operations::write_room return uint"). I intentionally do not
mark this patch by a real tag below.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-6-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
"N_TTY_BUF_SIZE" is private to n_tty and shall not be exposed to the
world. Definitely not in tty.h somewhere in the middle of "struct
tty_struct".
This is a remnant of moving "read_flags" to "struct n_tty_data" in
commit 3fe780b379 ("TTY: move ldisc data from tty_struct: bitmaps").
But some cleanup was needed first (in previous patches).
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-5-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Convert TTY_* macros (flags) to an enum. This allows for easier
kernel-doc (the comment needed fine tuning), grouping of these nicely,
and proper checking.
Note that these are bit positions. So they are used such as
test_bit(TTY_THROTTLED, ...). Given these are not the user API (only
in-kernel API/ABI), the bit positions are NOT preserved in this patch.
All are renumbered naturally using the enum-auto-numbering.
Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250317070046.24386-2-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
