kernel/drivers/tty/serial/stm32-usart.c, branch linux-6.9.y

serial: stm32: Reset .throttled state in .startup()

2024-04-17T11:26:45Z

When an UART is opened that still has .throttled set from a previous open, the RX interrupt is enabled but the irq handler doesn't consider it. This easily results in a stuck irq with the effect to occupy the CPU in a tight loop. So reset the throttle state in .startup() to ensure that RX irqs are handled. Fixes: d1ec8a2eabe9 ("serial: stm32: update throttle and unthrottle ops for dma mode") Cc: stable@vger.kernel.org Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/a784f80d3414f7db723b2ec66efc56e1ad666cbf.1713344161.git.u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman

serial: stm32: Return IRQ_NONE in the ISR if no handling happend

2024-04-17T11:26:45Z

If there is a stuck irq that the handler doesn't address, returning IRQ_HANDLED unconditionally makes it impossible for the irq core to detect the problem and disable the irq. So only return IRQ_HANDLED if an event was handled. A stuck irq is still problematic, but with this change at least it only makes the UART nonfunctional instead of occupying the (usually only) CPU by 100% and so stall the whole machine. Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver") Cc: stable@vger.kernel.org Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/5f92603d0dfd8a5b8014b2b10a902d91e0bb881f.1713344161.git.u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman

Merge 6.8-rc6 into tty-next

2024-02-27T05:22:13Z

We need the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman

serial: stm32: do not always set SER_RS485_RX_DURING_TX if RS485 is enabled

2024-02-19T08:43:37Z

Before commit 07c30ea5861f ("serial: Do not hold the port lock when setting rx-during-tx GPIO") the SER_RS485_RX_DURING_TX flag was only set if the rx-during-tx mode was not controlled by a GPIO. Now the flag is set unconditionally when RS485 is enabled. This results in an incorrect setting if the rx-during-tx GPIO is not asserted. Fix this by setting the flag only if the rx-during-tx mode is not controlled by a GPIO and thus restore the correct behaviour. Cc: stable@vger.kernel.org # 6.6+ Fixes: 07c30ea5861f ("serial: Do not hold the port lock when setting rx-during-tx GPIO") Signed-off-by: Lino Sanfilippo Link: https://lore.kernel.org/r/20240216224709.9928-1-l.sanfilippo@kunbus.com Signed-off-by: Greg Kroah-Hartman

serial: stm32: get FIFO size from hwcfg register

2024-01-28T03:04:11Z

Since STM32MP25, FIFO size could vary regarding the STM32MPxx version. So we get this size from "hwcfgr1" register and compute threshold values corresponding to the ratio given by reference manual. As STM32MP1x, STM32MP25 and STM32H7 share the same compatible and STM32H7 doesn't have a register to get FIFO size, we force FIFO size to 16 in case of zero read from hwcfgr1 register. Signed-off-by: Valentin Caron Link: https://lore.kernel.org/r/20240112095300.2004878-5-valentin.caron@foss.st.com Signed-off-by: Greg Kroah-Hartman

serial: stm32: implement prescaler tuning to compute low baudrate

2024-01-28T03:04:11Z

In the case of high USART input clock and low baud rate, BRR value is not enough to get correct baud rate. So here we use USART prescaler to divide USART input clock to get the correct baud rate. PRESC register is only available since stm32h7. Signed-off-by: Valentin Caron Link: https://lore.kernel.org/r/20240112095300.2004878-2-valentin.caron@foss.st.com Signed-off-by: Greg Kroah-Hartman

serial: Do not hold the port lock when setting rx-during-tx GPIO

2024-01-04T15:26:09Z

Both the imx and stm32 driver set the rx-during-tx GPIO in rs485_config(). Since this function is called with the port lock held, this can be a problem in case that setting the GPIO line can sleep (e.g. if a GPIO expander is used which is connected via SPI or I2C). Avoid this issue by moving the GPIO setting outside of the port lock into the serial core and thus making it a generic feature. Also with commit c54d48543689 ("serial: stm32: Add support for rs485 RX_DURING_TX output GPIO") the SER_RS485_RX_DURING_TX flag is only set if a rx-during-tx GPIO is _not_ available, which is wrong. Fix this, too. Furthermore reset old GPIO settings in case that changing the RS485 configuration failed. Fixes: c54d48543689 ("serial: stm32: Add support for rs485 RX_DURING_TX output GPIO") Fixes: ca530cfa968c ("serial: imx: Add support for RS485 RX_DURING_TX output GPIO") Cc: Shawn Guo Cc: Sascha Hauer Cc: Signed-off-by: Lino Sanfilippo Link: https://lore.kernel.org/r/20240103061818.564-2-l.sanfilippo@kunbus.com Signed-off-by: Greg Kroah-Hartman

serial: stm32: Convert to platform remove callback returning void

2023-11-23T19:12:34Z

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/20231110152927.70601-43-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman

serial: stm32: Use port lock wrappers

2023-09-18T09:18:15Z

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 Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20230914183831.587273-65-john.ogness@linutronix.de Signed-off-by: Greg Kroah-Hartman

serial: stm32: add support for break control

2023-09-18T09:14:42Z

Add support for break control to the stm32 serial driver. Signed-off-by: Erwan Le Ray Signed-off-by: Valentin Caron Reviewed-by: Jiri Slaby Link: https://lore.kernel.org/r/20230906151547.840302-1-valentin.caron@foss.st.com Signed-off-by: Greg Kroah-Hartman