kernel/drivers/tty/serial/meson_uart.c, branch linux-6.9.y

serial: meson: Use uart_prepare_sysrq_char().

2024-03-02T21:06:21Z

The port lock is a spinlock_t which is becomes a sleeping lock on PREEMPT_RT. The driver splits the locking function into two parts: local_irq_save() and uart_port_lock() and this breaks PREEMPT_RT. Delay handling sysrq until port lock is dropped. Remove the special case in the console write routine an always use the complete locking function. Cc: Kevin Hilman Cc: Jerome Brunet Cc: linux-arm-kernel@lists.infradead.org Cc: linux-amlogic@lists.infradead.org Signed-off-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20240301215246.891055-5-bigeasy@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: meson: Convert to platform remove callback returning void

2023-11-23T19:12:32Z

The .remove() callback for a platform driver returns an int which makes many driver authors wrongly assume it's possible to do error handling by returning an error code. However the value returned is ignored (apart from emitting a warning) and this typically results in resource leaks. To improve here there is a quest to make the remove callback return void. In the first step of this quest all drivers are converted to .remove_new(), which already returns void. Eventually after all drivers are converted, .remove_new() will be renamed to .remove(). Trivially convert this driver from always returning zero in the remove callback to the void returning variant. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20231110152927.70601-24-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman

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

2023-10-17T08:17:01Z

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

2023-10-10T06:50:49Z

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

2023-09-18T09:18:12Z

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"

2023-08-27T09:43:01Z

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

2023-08-22T13:29:01Z

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

2023-07-30T11:53:06Z

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

2023-07-25T18:22:08Z

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

2023-07-25T18:22:08Z

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