kernel/linux.git/drivers/tty/serial/max310x.c, branch linux-7.0.y

serial: max310x: improve interrupt handling

2025-09-12T14:10:16+00:00

When there is a heavy load of receiving characters to all four UART's, the warning 'Hardware RX FIFO overrun' is sometimes detected. The current implementation always service first the highest UART until no more interrupt and then service another UART (ex: UART3 will be serviced for as long as there are interrupts for it, then UART2, etc). This commit handle all individual interrupt sources before reading the global IRQ register again. This commit has also a nice side-effect of improving the efficiency of the driver by reducing the number of reads of the global IRQ register. Signed-off-by: Tapio Reijonen Reviewed-by: Jiri Slaby Reviewed-by: Hugo Villeneuve Link: https://lore.kernel.org/r/20250908-master-max310x-improve-interrupt-handling-v3-1-91985e82ba39@vaisala.com Signed-off-by: Greg Kroah-Hartman

tty: serial: Modify the use of dev_err_probe()

2025-08-21T06:09:20+00:00

The dev_err_probe() doesn't do anything when error is '-ENOMEM'. Make the following two changes: (1) Replace -ENOMEM with -ENOSPC in max3100_probe(). (2) Just return -ENOMEM instead in max310x_probe(). Signed-off-by: Xichao Zhao Reviewed-by: Jiri Slaby Link: https://lore.kernel.org/r/20250819120927.607744-1-zhao.xichao@vivo.com Signed-off-by: Greg Kroah-Hartman

serial: max310x: Add error checking in probe()

2025-08-14T09:58:43+00:00

Check if devm_i2c_new_dummy_device() fails. Fixes: 2e1f2d9a9bdb ("serial: max310x: implement I2C support") Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/r/aJTMPZiKqeXSE-KM@stanley.mountain Signed-off-by: Greg Kroah-Hartman

treewide: rename GPIO set callbacks back to their original names

2025-08-07T08:07:06+00:00

The conversion of all GPIO drivers to using the .set_rv() and .set_multiple_rv() callbacks from struct gpio_chip (which - unlike their predecessors - return an integer and allow the controller drivers to indicate failures to users) is now complete and the legacy ones have been removed. Rename the new callbacks back to their original names in one sweeping change. Signed-off-by: Bartosz Golaszewski

serial: max310x: use new GPIO line value setter callbacks

2025-04-11T14:52:25+00:00

struct gpio_chip now has callbacks for setting line values that return an integer, allowing to indicate failures. Convert the driver to using them. Signed-off-by: Bartosz Golaszewski Link: https://lore.kernel.org/r/20250408-gpiochip-set-rv-tty-v1-1-fb49444827d4@linaro.org Signed-off-by: Greg Kroah-Hartman

tty: serial: max310x: convert to use maple tree register cache

2024-04-09T14:50:36+00:00

The maple tree register cache is based on a much more modern data structure than the rbtree cache and makes optimisation choices which are probably more appropriate for modern systems than those made by the rbtree cache. Signed-off-by: wangkaiyuan Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20240318064036.1656-1-wangkaiyuan@inspur.com Signed-off-by: Greg Kroah-Hartman

tty: serial: switch from circ_buf to kfifo

2024-04-09T13:28:03+00:00

Switch from struct circ_buf to proper kfifo. kfifo provides much better API, esp. when wrap-around of the buffer needs to be taken into account. Look at pl011_dma_tx_refill() or cpm_uart_tx_pump() changes for example. Kfifo API can also fill in scatter-gather DMA structures, so it easier for that use case too. Look at lpuart_dma_tx() for example. Note that not all drivers can be converted to that (like atmel_serial), they handle DMA specially. Note that usb-serial uses kfifo for TX for ages. omap needed a bit more care as it needs to put a char into FIFO to start the DMA transfer when OMAP_DMA_TX_KICK is set. In that case, we have to do kfifo_dma_out_prepare twice: once to find out the tx_size (to find out if it is worths to do DMA at all -- size >= 4), the second time for the actual transfer. All traces of circ_buf are removed from serial_core.h (and its struct uart_state). Signed-off-by: Jiri Slaby (SUSE) Cc: Al Cooper Cc: Matthias Brugger Cc: AngeloGioacchino Del Regno Cc: Kumaravel Thiagarajan Cc: Tharun Kumar P Cc: Russell King Cc: Vineet Gupta Cc: Richard Genoud Cc: Nicolas Ferre Cc: Alexandre Belloni Cc: Claudiu Beznea Cc: Alexander Shiyan Cc: Baruch Siach Cc: Maciej W. Rozycki Cc: Shawn Guo Cc: Sascha Hauer Cc: Fabio Estevam Cc: Neil Armstrong Cc: Kevin Hilman Cc: Jerome Brunet Cc: Martin Blumenstingl Cc: Taichi Sugaya Cc: Takao Orito Cc: Bjorn Andersson Cc: Konrad Dybcio Cc: Pali Rohár Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Christophe Leroy Cc: Aneesh Kumar K.V Cc: Naveen N. Rao Cc: Manivannan Sadhasivam Cc: Krzysztof Kozlowski Cc: Alim Akhtar Cc: Laxman Dewangan Cc: Thierry Reding Cc: Jonathan Hunter Cc: Orson Zhai Cc: Baolin Wang Cc: Chunyan Zhang Cc: Patrice Chotard Cc: Maxime Coquelin Cc: Alexandre Torgue Cc: David S. Miller Cc: Hammer Hsieh Cc: Peter Korsgaard Cc: Timur Tabi Cc: Michal Simek Cc: Sumit Semwal Cc: Christian König Link: https://lore.kernel.org/r/20240405060826.2521-13-jirislaby@kernel.org Signed-off-by: Greg Kroah-Hartman

Merge 6.8-rc3 into tty-next

2024-02-04T14:21:02+00:00

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

serial: max310x: prevent infinite while() loop in port startup

2024-01-28T03:09:10+00:00

If there is a problem after resetting a port, the do/while() loop that checks the default value of DIVLSB register may run forever and spam the I2C bus. Add a delay before each read of DIVLSB, and a maximum number of tries to prevent that situation from happening. Also fail probe if port reset is unsuccessful. Fixes: 10d8b34a4217 ("serial: max310x: Driver rework") Cc: stable@vger.kernel.org Signed-off-by: Hugo Villeneuve Link: https://lore.kernel.org/r/20240116213001.3691629-5-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman

serial: max310x: fail probe if clock crystal is unstable

2024-01-28T03:09:10+00:00

A stable clock is really required in order to use this UART, so log an error message and bail out if the chip reports that the clock is not stable. Fixes: 4cf9a888fd3c ("serial: max310x: Check the clock readiness") Cc: stable@vger.kernel.org Suggested-by: Jan Kundrát Link: https://www.spinics.net/lists/linux-serial/msg35773.html Signed-off-by: Hugo Villeneuve Link: https://lore.kernel.org/r/20240116213001.3691629-4-hugo@hugovil.com Signed-off-by: Greg Kroah-Hartman