kernel/linux.git/drivers/tty/serial/meson_uart.c, branch v6.7

tty: serial: meson: fix hard LOCKUP on crtscts mode

2023-10-17T08:17:01+00:00

There might be hard lockup if we set crtscts mode on port without RTS/CTS configured: # stty -F /dev/ttyAML6 crtscts; echo 1 > /dev/ttyAML6; echo 2 > /dev/ttyAML6 [ 95.890386] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 95.890857] rcu: 3-...0: (201 ticks this GP) idle=e33c/1/0x4000000000000000 softirq=5844/5846 fqs=4984 [ 95.900212] rcu: (detected by 2, t=21016 jiffies, g=7753, q=296 ncpus=4) [ 95.906972] Task dump for CPU 3: [ 95.910178] task:bash state:R running task stack:0 pid:205 ppid:1 flags:0x00000202 [ 95.920059] Call trace: [ 95.922485] __switch_to+0xe4/0x168 [ 95.925951] 0xffffff8003477508 [ 95.974379] watchdog: Watchdog detected hard LOCKUP on cpu 3 [ 95.974424] Modules linked in: 88x2cs(O) rtc_meson_vrtc Possible solution would be to not allow to setup crtscts on such port. Tested on S905X3 based board. Fixes: ff7693d079e5 ("ARM: meson: serial: add MesonX SoC on-chip uart driver") Cc: stable@vger.kernel.org Signed-off-by: Pavel Krasavin Reviewed-by: Neil Armstrong Reviewed-by: Dmitry Rokosov v6: stable tag added v5: https://lore.kernel.org/lkml/OF43DA36FF.2BD3BB21-ON00258A47.005A8125-00258A47.005A9513@gdc.ru/ added missed Reviewed-by tags, Fixes tag added according to Dmitry and Neil notes v4: https://lore.kernel.org/lkml/OF55521400.7512350F-ON00258A47.003F7254-00258A47.0040E15C@gdc.ru/ More correct patch subject according to Jiri's note v3: https://lore.kernel.org/lkml/OF6CF5FFA0.CCFD0E8E-ON00258A46.00549EDF-00258A46.0054BB62@gdc.ru/ "From:" line added to the mail v2: https://lore.kernel.org/lkml/OF950BEF72.7F425944-ON00258A46.00488A76-00258A46.00497D44@gdc.ru/ braces for single statement removed according to Dmitry's note v1: https://lore.kernel.org/lkml/OF28B2B8C9.5BC0CD28-ON00258A46.0037688F-00258A46.0039155B@gdc.ru/ Link: https://lore.kernel.org/r/OF66360032.51C36182-ON00258A48.003F656B-00258A48.0040092C@gdc.ru Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: Add a earlycon for the S4 SoC

2023-10-10T06:50:49+00:00

The new Amlogic S4 SoC does not have a always-on uart, so add OF_EARLYCON_DECLARE for it. Amlogic T7 will use this as fallback. Signed-off-by: Lucas Tanure Reviewed-by: Neil Armstrong Link: https://lore.kernel.org/r/20231009121151.4509-1-tanure@linux.com Signed-off-by: Greg Kroah-Hartman

serial: meson: Use port lock wrappers

2023-09-18T09:18:12+00:00

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 Acked-by: Neil Armstrong Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-38-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman

Revert "tty: serial: meson: Add a earlycon for the T7 SoC"

2023-08-27T09:43:01+00:00

This reverts commit 6a4197f9763325043abf7690a21124a9facbf52e New SoC will use ttyS0 instead of ttyAML, so T7 SoC doesn't need a OF_EARLYCON_DECLARE. Fixes: 6a4197f97633 ("tty: serial: meson: Add a earlycon for the T7 SoC") Signed-off-by: Lucas Tanure Link: https://lore.kernel.org/r/20230827082944.5100-1-tanure@linux.com Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: Add a earlycon for the T7 SoC

2023-08-22T13:29:01+00:00

The new Amlogic T7 SoC does not have a always-on uart, so add OF_EARLYCON_DECLARE for it. Signed-off-by: Lucas Tanure Acked-by: Neil Armstrong Link: https://lore.kernel.org/r/20230814080128.143613-2-tanure@linux.com Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: refactor objects definition for different devnames

2023-07-30T11:53:06+00:00

Macroses for name generation are not useful. They hide the real place for object declaration. Instead, use direct names such as 'meson_uart_driver_*' and 'meson_serial_console_*' for all objects. Additionally, rename 'MESON_SERIAL_CONSOLE_DEFINE()' to 'MESON_SERIAL_CONSOLE()', and 'MESON_UART_DRIVER_DEFINE()' to 'MESON_UART_DRIVER()' to simplify the code. Signed-off-by: Dmitry Rokosov Suggested-by: Neil Armstrong Link: https://lore.kernel.org/r/20230728071522.17503-1-ddrokosov@sberdevices.ru Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: add independent uart_data for A1 SoC family

2023-07-25T18:22:08+00:00

Implement separate uart_data to ensure proper devname value for the A1 SoC family. Use 'ttyS' devname, as required by the A1 architecture, instead of the legacy gx architecture. Signed-off-by: Dmitry Rokosov Reviewed-by: Neil Armstrong Link: https://lore.kernel.org/r/20230705181833.16137-6-ddrokosov@sberdevices.ru Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: introduce separate uart_data for S4 SoC family

2023-07-25T18:22:08+00:00

In order to use the correct devname value for the S4 SoC family, it is imperative that we implement separate uart_data. Unlike the legacy g12a architecture, the S4 architecture should employ the use of 'ttyS' devname. Signed-off-by: Dmitry Rokosov Reviewed-by: Neil Armstrong Link: https://lore.kernel.org/r/20230705181833.16137-5-ddrokosov@sberdevices.ru Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: apply ttyS devname instead of ttyAML for new SoCs

2023-07-25T18:22:07+00:00

It is worth noting that the devname ttyS is a widely recognized tty name and is commonly used by many uart device drivers. Given the established usage and compatibility concerns, it may not be feasible to change the devname for older SoCs. However, for new definitions, it is acceptable and even recommended to use a new devname to help ensure clarity and avoid any potential conflicts on lower or upper software levels. For more information please refer to IRC discussion at [1]. Links: [1]: https://libera.irclog.whitequark.org/linux-amlogic/2023-07-03 Signed-off-by: Dmitry Rokosov Link: https://lore.kernel.org/r/20230705181833.16137-4-ddrokosov@sberdevices.ru Signed-off-by: Greg Kroah-Hartman

tty: serial: meson: redesign the module to platform_driver

2023-07-25T18:22:07+00:00

Actually, the meson_uart module is already a platform_driver, but it is currently registered manually and the uart core registration is run outside the probe() scope, which results in some restrictions. For instance, it is not possible to communicate with the OF subsystem because it requires an initialized device object. To address this issue, apply module_platform_driver() instead of direct module init/exit routines. Additionally, move uart_register_driver() to the driver probe(), and destroy manual console registration because it's already run in the uart_register_driver() flow. Signed-off-by: Dmitry Rokosov Reviewed-by: Neil Armstrong Link: https://lore.kernel.org/r/20230705181833.16137-3-ddrokosov@sberdevices.ru Signed-off-by: Greg Kroah-Hartman