linux.git/include/linux/serdev.h, branch v7.1-rc2

Merge tag 'tty-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2026-04-19T15:44:41+00:00

Pull tty/serial updates from Greg KH:
 "Here is the set of tty and serial driver changes for 7.1-rc1.

  Not much here this cycle, biggest thing is the removal of an old
  driver that never got any actual hardware support (esp32), and the
  second try to moving the tty ports to their own workqueues (first try
  was in 7.0-rc1 but was reverted due to problems)

  Otherwise it's just a small set of driver updates and some vt modifier
  key enhancements.

  All have been in linux-next for a while with no reported issues"

* tag 'tty-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (35 commits)
  tty: serial: ip22zilog: Fix section mispatch warning
  hvc/xen: Check console connection flag
  serial: sh-sci: Add support for RZ/G3L RSCI
  dt-bindings: serial: renesas,rsci: Document RZ/G3L SoC
  tty: atmel_serial: update outdated reference to atmel_tasklet_func()
  serial: xilinx_uartps: Drop unused include
  serial: qcom-geni: drop stray newline format specifier
  serial: 8250: loongson: Enable building on MIPS Loongson64
  dt-bindings: serial: 8250: Add Loongson 3A4000 uart compatible
  serial: 8250_fintek: Add support for F81214E
  tty: tty_port: add workqueue to flip TTY buffer
  vt: support ITU-T T.416 color subparameters
  serial: qcom-geni: Fix RTS behavior with flow control
  tty: serial: imx: keep dma request disabled before dma transfer setup
  tty: serial: 8250: Add SystemBase Multi I/O cards
  serial: pic32_uart: allow driver to be compiled on all architectures with COMPILE_TEST
  serial: tegra: remove Kconfig dependency on APB DMA controller
  dt-bindings: serial: amlogic,meson-uart: Add compatible string for A9
  dt-bindings: serial: atmel,at91-usart: add microchip,lan9691-usart
  serial: auart: check clk_enable() return in console write
  ...

serdev: Add an API to find the serdev controller associated with the devicetree node

2026-03-31T07:48:42+00:00

Add of_find_serdev_controller_by_node() API to find the serdev controller
device associated with the devicetree node.

Tested-by: Hans de Goede  # ThinkPad T14s gen6 (arm64)
Reviewed-by: Bartosz Golaszewski 
Signed-off-by: Manivannan Sadhasivam 
Reviewed-by: Rob Herring (Arm) 
Link: https://patch.msgid.link/20260326-pci-m2-e-v7-2-43324a7866e6@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski

serdev: Convert to_serdev_*() helpers to macros and use container_of_const()

2026-03-31T07:48:42+00:00

If these helpers receive the 'const struct device' pointer, then the const
qualifier will get dropped, leading to below warning:

warning: passing argument 1 of ‘to_serdev_device_driver’ discards 'const'
qualifier from pointer target type [-Wdiscarded-qualifiers]

This is not an issue as of now, but with the future commits adding serdev
device based driver matching, this warning will get triggered. Hence,
convert these helpers to macros so that the qualifier get preserved and
also use container_of_const() as container_of() is deprecated.

Tested-by: Hans de Goede  # ThinkPad T14s gen6 (arm64)
Reviewed-by: Bartosz Golaszewski 
Signed-off-by: Manivannan Sadhasivam 
Reviewed-by: Rob Herring (Arm) 
Link: https://patch.msgid.link/20260326-pci-m2-e-v7-1-43324a7866e6@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski

serdev: serdev.h: clean up kernel-doc comments

2026-03-12T14:07:31+00:00

Correct kernel-doc comment format and add a missing to avoid
kernel-doc warnings:

Warning: include/linux/serdev.h:49 struct member 'write_comp' not
 described in 'serdev_device'
Warning: include/linux/serdev.h:49 struct member 'write_lock' not
 described in 'serdev_device'
Warning: include/linux/serdev.h:68 struct member 'shutdown' not described
 in 'serdev_device_driver'
Warning: include/linux/serdev.h:134 function parameter 'serdev' not
 described in 'serdev_device_put'
Warning: include/linux/serdev.h:162 function parameter 'ctrl' not
 described in 'serdev_controller_put'

Signed-off-by: Randy Dunlap 
Link: https://patch.msgid.link/20260311052347.305612-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman

serdev: Provide a bustype shutdown function

2025-12-17T14:08:18+00:00

To prepare serdev driver to migrate away from struct device_driver::shutdown
(and then eventually remove that callback) create a serdev driver shutdown
callback and migration code to keep the existing behaviour. Note this
introduces a warning for each driver at register time that isn't converted
yet to that callback.

Signed-off-by: Uwe Kleine-König 
Link: https://patch.msgid.link/ab518883e3ed0976a19cb5b5b5faf42bd3a655b7.1765526117.git.u.kleine-koenig@baylibre.com
Signed-off-by: Greg Kroah-Hartman

tty: serdev: drop serdev_controller_ops::write_room()

2025-03-20T15:00:51+00:00

In particular, serdev_device_write_room() is not called, so the whole
serdev's write_room() can go.

Signed-off-by: Jiri Slaby (SUSE) 
Cc: Rob Herring 
Link: https://lore.kernel.org/r/20250317070046.24386-17-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman

treewide, serdev: change receive_buf() return type to size_t

2024-01-28T02:13:53+00:00

receive_buf() is called from ttyport_receive_buf() that expects values
">= 0" from serdev_controller_receive_buf(), change its return type from
ssize_t to size_t.

The need for this clean-up was noticed while fixing a warning, see
commit 94d053942544 ("Bluetooth: btnxpuart: fix recv_buf() return value").
Changing the callback prototype to return an unsigned seems the best way
to document the API and ensure that is properly used.

GNSS drivers implementation of serdev receive_buf() callback return
directly the return value of gnss_insert_raw(). gnss_insert_raw()
returns a signed int, however this is not an issue since the value
returned is always positive, because of the kfifo_in() implementation.
gnss_insert_raw() could be changed to return also an unsigned, however
this is not implemented here as request by the GNSS maintainer Johan
Hovold.

Suggested-by: Jiri Slaby 
Link: https://lore.kernel.org/all/087be419-ec6b-47ad-851a-5e1e3ea5cfcc@kernel.org/
Signed-off-by: Francesco Dolcini 
Acked-by: Jonathan Cameron  #for-iio
Reviewed-by: Johan Hovold 
Reviewed-by: Rob Herring 
Reviewed-by: Alex Elder 
Acked-by: Maximilian Luz   # for platform/surface
Acked-by: Lee Jones 
Acked-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20240122180551.34429-1-francesco@dolcini.it
Signed-off-by: Greg Kroah-Hartman

tty: serdev: convert to u8 and size_t

2023-12-08T11:02:38+00:00

Switch character types to u8 and sizes to size_t. To conform to
characters/sizes in the rest of the tty layer.

This patch converts struct serdev_device_ops hooks and its
instantiations.

Signed-off-by: "Jiri Slaby (SUSE)" 
Cc: Rob Herring 
Acked-by: Johan Hovold 
Link: https://lore.kernel.org/r/20231206073712.17776-24-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman

tty: serdev: convert to u8 and size_t in serdev_controller_ops

2023-12-08T11:02:38+00:00

Switch character types to u8 and sizes to size_t. To conform to
characters/sizes in the rest of the tty layer.

In this patch, only struct serdev_controller_ops hooks. The rest will
follow.

Signed-off-by: "Jiri Slaby (SUSE)" 
Cc: Rob Herring 
Link: https://lore.kernel.org/r/20231206073712.17776-23-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman

serial: core: Move tty and serdev to be children of serial core port device

2023-11-25T07:23:16+00:00

Let's move tty and serdev controller to be children of the serial core port
device. This way the runtime PM usage count of a child device propagates
to the serial hardware device.

The tty and serdev devices are associated with a specific serial port of
a serial hardware controller device, and we now have serial core hierarchy
of controllers and ports.

The tty device moves happily with just a change of the parent device and
update of device_find_child() handling. The serdev device init needs some
changes to separate the serial hardware controller device from the parent
device.

With this change the tty devices move under sysfs similar to this x86_64
qemu example of a diff of "find /sys -name ttyS*":

 /sys/class/tty/ttyS0
 /sys/class/tty/ttyS3
 /sys/class/tty/ttyS1
-/sys/devices/pnp0/00:04/tty/ttyS0
-/sys/devices/platform/serial8250/tty/ttyS2
-/sys/devices/platform/serial8250/tty/ttyS3
-/sys/devices/platform/serial8250/tty/ttyS1
+/sys/devices/pnp0/00:04/00:04:0/00:04:0.0/tty/ttyS0
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.3/tty/ttyS3
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.1/tty/ttyS1
+/sys/devices/platform/serial8250/serial8250:0/serial8250:0.2/tty/ttyS2

If a serdev device is used instead of a tty, it moves in a similar way.

Suggested-by: Johan Hovold 
Cc: Maximilian Luz 
Cc: Rob Herring 
Signed-off-by: Tony Lindgren 
Link: https://lore.kernel.org/r/20231113080758.30346-1-tony@atomide.com
Signed-off-by: Greg Kroah-Hartman