[PATCH v3 0/4] cros_kbd_led_backlight: allow binding through cros_ec mfd device

[Thomas Weißschuh]

Extend the cros_ec MFD device to also load cros_kbd_led_backlight
when the EC reports EC_FEATURE_PWM_KEYB.
As the driver can now be probed multiple times, some preparation in the
LED core is necessary to avoid name collisions.

Patch 1 is a general cleanup for the LED core.
Patch 2 modifies the LED core to skip the default collision handling.
Patch 3 adds the new probing logic to cros_kbd_led_backlight.
Patch 4 wires up the driver to the cros_ec mfd devices.

The helper keyboard_led_is_mfd_device is a bit iffy.
But using match data doesn't work.

* driver_data from platform_device_id is overwritten by the mfd platform data
* Setting the driver_data in drivers/mfd/cros_ec_dev.c would expose the
internals of cros_kbd_led_backlight

Tested on a Framework 13 AMD, Firmware 3.05, and a Jinlon Chromebook.

To: Lee Jones <lee@xxxxxxxxxx>
To: Benson Leung <bleung@xxxxxxxxxxxx>
To: Guenter Roeck <groeck@xxxxxxxxxxxx>
To: Tzung-Bi Shih <tzungbi@xxxxxxxxxx>
To: Pavel Machek <pavel@xxxxxx>
Cc: chrome-platform@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: Dustin Howett <dustin@xxxxxxxxxx>
Cc: Mario Limonciello <mario.limonciello@xxxxxxx>
Cc: linux-leds@xxxxxxxxxxxxxxx
Cc: Rajas Paranjpe <paranjperajas@xxxxxxxxx>
Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>

Changes in v3:
- Avoid probing multiple times (Confirmed by Rajas)
- Add Kconfig dependency on MFD_CROS_EC_DEV
- Link to v2: https://lore.kernel.org/r/20240511-cros_ec-kbd-led-framework-v2-0-b20c48109e46@xxxxxxxxxxxxxx

Changes in v2:
- Fix build with CONFIG_MFD_CROS_EC_DEV=n (kernel test robot)
- Split out mfd registration into own commit (Lee)
- Simplify keyboard_led_is_mfd_device() with mfd_get_cell()
- Link to v1: https://lore.kernel.org/r/20240505-cros_ec-kbd-led-framework-v1-1-bfcca69013d2@xxxxxxxxxxxxxx

---
Thomas Weißschuh (4):
      leds: class: warn about name collisions earlier
      leds: add flag to avoid automatic renaming of led devices
      platform/chrome: cros_kbd_led_backlight: allow binding through mfd device
      mfd: cros_ec: Register keyboard backlight subdevice

 drivers/leds/led-class.c                         |  9 +++---
 drivers/mfd/cros_ec_dev.c                        |  9 ++++++
 drivers/platform/chrome/Kconfig                  |  2 +-
 drivers/platform/chrome/cros_kbd_led_backlight.c | 40 ++++++++++++++++++++++--
 include/linux/leds.h                             |  1 +
 5 files changed, 54 insertions(+), 7 deletions(-)
---
base-commit: 6fbf71854e2ddea7c99397772fbbb3783bfe15b5
change-id: 20240505-cros_ec-kbd-led-framework-7e2e831bc79c

Best regards,
-- 
Thomas Weißschuh <linux@xxxxxxxxxxxxxx>