[PATCH v2 00/11] Add Mobileye EyeQ5 support to the Nomadik I2C controller & use hrtimers for timeouts

[Théo Lebrun]

Hi,

This series adds two tangent features to the Nomadik I2C controller:

 - Add a new compatible to support Mobileye EyeQ5 which uses the same IP
   block as Nomadik.

   It has two quirks to be handled:
    - The memory bus only supports 32-bit accesses. Avoid readb() and
      writeb() calls that might generate byte load/store instructions.
    - We must write a value into a shared register region (OLB)
      depending on the I2C bus speed.

 - Allow xfer timeouts below one jiffy by using a waitqueue and hrtimers
   instead of a completion.

   The situation to be addressed is:
    - Many devices on the same I2C bus.
    - One xfer to each device is sent at regular interval.
    - One device gets stuck and does not answer.
    - With long timeouts, following devices won't get their message. A
      shorter timeout ensures we can still talk to the following
      devices.

   This clashes a bit with the current i2c_adapter timeout field that
   stores a jiffies amount. We therefore avoid it and store the value
   in a private struct field, as a µs amount. If the timeout is less
   than a jiffy duration, we switch from standard jiffies timeout to
   hrtimers.

There is one patch targeting a hwmon dt-bindings file:
Documentation/devicetree/bindings/hwmon/lm75.yaml. The rest is touching
the I2C bus driver, its bindings and platform devicetrees.

About dependencies:
 - The series is based upon v6.8-rc6.
 - For testing on EyeQ5 hardware and devicetree patches, we need the
   base platform series from Grégory [0] and its dependency [1]. Both
   in mips-next [2].
 - Devicetree commits require the EyeQ5 syscon series [3] that provides
   the reset controller node.
 - The LM75 dt-bindings patch depends on the common schema
   hwmon-common.yaml series from Krzysztof [4]. Found in hwmon-next [5].

Have a nice day,
Théo Lebrun

[0]: https://lore.kernel.org/lkml/20240216174227.409400-1-gregory.clement@xxxxxxxxxxx/
[1]: https://lore.kernel.org/linux-mips/20240209-regname-v1-0-2125efa016ef@xxxxxxxxxxx/
[2]: https://git.kernel.org/pub/scm/linux/kernel/git/mips/linux.git/log/
[3]: https://lore.kernel.org/lkml/20240227-mbly-clk-v8-0-c57fbda7664a@xxxxxxxxxxx/
[4]: https://lore.kernel.org/lkml/20240224-dt-bindings-hwmon-common-v2-0-b446eecf5480@xxxxxxxxxx/
[5]: https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git/log/?h=hwmon-next

To: Linus Walleij <linus.walleij@xxxxxxxxxx>
To: Andi Shyti <andi.shyti@xxxxxxxxxx>
To: Rob Herring <robh+dt@xxxxxxxxxx>
To: Krzysztof Kozlowski <krzysztof.kozlowski+dt@xxxxxxxxxx>
To: Conor Dooley <conor+dt@xxxxxxxxxx>
To: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: <linux-i2c@xxxxxxxxxxxxxxx>
Cc: <devicetree@xxxxxxxxxxxxxxx>
Cc: <linux-kernel@xxxxxxxxxxxxxxx>
Cc: <linux-mips@xxxxxxxxxxxxxxx>
Cc: Gregory Clement <gregory.clement@xxxxxxxxxxx>
Cc: Vladimir Kondratiev <vladimir.kondratiev@xxxxxxxxxxxx>
Cc: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxx>
Cc: Tawfik Bayouk <tawfik.bayouk@xxxxxxxxxxxx>
Signed-off-by: Théo Lebrun <theo.lebrun@xxxxxxxxxxx>

Changes in v2:
- dt-bindings: i2c: st,nomadic-i2c:
  - Drop timeout-usecs property, rely on generic i2c-transfer-timeout-us.
  - Use phandle to syscon with cell args; remove mobileye,id prop; move
    mobileye,olb from if-statement to top-level.
- dt-bindings: hwmon: lm75:
  - Inherit from hwmon-common.yaml rather than declare generic label property.
- i2c: nomadik: (ie driver code)
  - Parse i2c-transfer-timeout-us rather than custom timeout-usecs property.
  - Introduce readb/writeb helpers with fallback to readl/writel.
  - Avoid readb() on Mobileye.
  - Use mobileye,olb cell args to get controller index rather than mobileye,id.
  - Take 5 Reviewed-by Linus Walleij.
- MIPS: mobileye: (ie devicetrees)
  - Use mobileye,olb with cell args rather than mobileye,id.
  - Squash reset commit.
  - Add i2c-transfer-timeout-us value of 10ms to all controllers.
  - Rename LM75 instance from tmp112@48 to temperature-sensor@48.
- Link to v1: https://lore.kernel.org/r/20240215-mbly-i2c-v1-0-19a336e91dca@xxxxxxxxxxx

---
Théo Lebrun (11):
      dt-bindings: i2c: nomadik: add mobileye,eyeq5-i2c bindings and example
      dt-bindings: hwmon: lm75: use common hwmon schema
      i2c: nomadik: rename private struct pointers from dev to priv
      i2c: nomadik: simplify IRQ masking logic
      i2c: nomadik: use bitops helpers
      i2c: nomadik: support short xfer timeouts using waitqueue & hrtimer
      i2c: nomadik: replace jiffies by ktime for FIFO flushing timeout
      i2c: nomadik: fetch i2c-transfer-timeout-us property from devicetree
      i2c: nomadik: support Mobileye EyeQ5 I2C controller
      MIPS: mobileye: eyeq5: add 5 I2C controller nodes
      MIPS: mobileye: eyeq5: add evaluation board I2C temp sensor

 Documentation/devicetree/bindings/hwmon/lm75.yaml  |   3 +-
 .../devicetree/bindings/i2c/st,nomadik-i2c.yaml    |  48 +-
 arch/mips/boot/dts/mobileye/eyeq5-epm5.dts         |   8 +
 arch/mips/boot/dts/mobileye/eyeq5.dtsi             |  75 +++
 drivers/i2c/busses/i2c-nomadik.c                   | 720 ++++++++++++---------
 5 files changed, 541 insertions(+), 313 deletions(-)
---
base-commit: a6cc37d1a531e1c99e7989001a0529b443397900
change-id: 20231023-mbly-i2c-7c2fbbb1299f

Best regards,
-- 
Théo Lebrun <theo.lebrun@xxxxxxxxxxx>