[PATCH v4 0/9] serial: sc16is7xx: fix GPIO regression and rs485 improvements

[Hugo Villeneuve <hugo@hugovil.com>]

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

Hello,
this patch series mainly fixes a GPIO regression and improve RS485 flags and
properties detection from DT.

It now also includes various small fixes and improvements that were previously
sent as separate patches, but that made testing everything difficult.

Patch 1 fixes an issue when debugging IOcontrol register. After testing the GPIO
regression patches (patches 6 and 7, tests done by Lech Perczak), it appers that
this patch is also necessary for having the correct IOcontrol register values.

Patch 2 introduces a delay after a reset operation to respect datasheet
timing recommandations.

Patch 3 fixes an issue with init of first port during probing.

Patch 4 fixes a bug with the output value when first setting the GPIO direction.

Patch 5 is a refactor of GPIO registration code.

Patches 6 and 7 fix a GPIO regression by (re)allowing to choose GPIO function
for GPIO pins shared with modem status lines.

Patch 8 allows to read common rs485 device-tree flags and properties.

Patch 9 improves comments about chip variants.

I have tested the changes on a custom board with two SC16IS752 DUART using a
Variscite IMX8MN NANO SOM.

Thank you.

Link: [v1] https://lkml.org/lkml/2023/5/17/967
      [v1] https://lkml.org/lkml/2023/5/17/777
      [v1] https://lkml.org/lkml/2023/5/17/780
      [v1] https://lkml.org/lkml/2023/5/17/785
      [v1] https://lkml.org/lkml/2023/5/17/1311
      [v2] https://lkml.org/lkml/2023/5/18/516
      [v3] https://lkml.org/lkml/2023/5/25/7

Changes for V3:
- Integrated all patches into single serie to facilitate debugging and tests.
- Reduce number of exported GPIOs depending on new property
  nxp,modem-control-line-ports
- Added additional example in DT bindings

Changes for V4:
- Increase reset post delay to relax scheduler.
- Put comments patches at the end.
- Remove Fixes tag for patch "mark IOCONTROL register as volatile".
- Improve commit messages after reviews.
- Fix coding style issues after reviews.
- Change GPIO registration to always register the maximum number of GPIOs
  supported by the chip, but maks-out GPIOs declared as modem control lines.
- Add patch to refactor GPIO registration.
- Remove patch "serial: sc16is7xx: fix syntax error in comments".
- Remove patch "add dump registers function"

Hugo Villeneuve (9):
  serial: sc16is7xx: mark IOCONTROL register as volatile
  serial: sc16is7xx: add post reset delay
  serial: sc16is7xx: fix broken port 0 uart init
  serial: sc16is7xx: fix bug when first setting GPIO direction
  serial: sc16is7xx: refactor GPIO controller registration
  dt-bindings: sc16is7xx: Add property to change GPIO function
  serial: sc16is7xx: fix regression with GPIO configuration
  serial: sc16is7xx: add call to get rs485 DT flags and properties
  serial: sc16is7xx: improve comments about variants

 .../bindings/serial/nxp,sc16is7xx.txt         |  46 ++++++
 drivers/tty/serial/sc16is7xx.c                | 150 +++++++++++++-----
 2 files changed, 156 insertions(+), 40 deletions(-)


base-commit: 8b817fded42d8fe3a0eb47b1149d907851a3c942
-- 
2.30.2