Add a hwmon driver that reports fan and temperature readings from the ChromeOS Embedded controller. There was an earlier effort in 2017 to add such a driver [0], but there was no followup after v1. The new driver is complete reimplementation based on newer APIs and with more features (temp sensor names). It only works on LPC-connected ECs, as only those implement direct memory-map access. For other busses the data would need to be read with a command. Adding some helpers was discussed in the previous patchset [1]. The EC protocols also support reading and writing fan curves but that is not implemented. Tested on a Framework 13 AMD, Firmware 3.05. [0] https://lore.kernel.org/all/1491602410-31518-1-git-send-email-moritz.fischer@xxxxxxxxx/ [1] https://lore.kernel.org/all/ac61bfca-bfa0-143b-c9ca-365b8026ce8d@xxxxxxxxxxxx/ --- Changes in v4: - Don't try to support variable-length reading in cros_ec_cmd_readmem() (Tzung-Bi) - Stylistic changes (Tzung-Bi) - Return -EOPNOTSUPP from read callbacks by default - Use nested if-blocks in read callback - Only allocate priv data after checking thermal version in memmap - Simplify calling protocol of _read() functions - Replace cros_ec_hwmon_read_temp_sensor_info() with cros_ec_cmd() - Link to v3: https://lore.kernel.org/r/20240527-cros_ec-hwmon-v3-0-e5cd5ab5ba37@xxxxxxxxxxxxxx Changes in v3: - Drop Mario's Reviewed-by tag, as the code has changed - Introduce cros_ec_cmd_readmem() for non-LPC compatibility - Report fault state for fans and temp sensors - Avoid adding unnecessary space characters to channel label - Drop thermal_version from priv data - Read fans during probing only once - Don't include linux/kernel.h - Move _read_temp_sensor_info to similar functions - Insert MFD entry alphabetically - Link to v2: https://lore.kernel.org/r/20240507-cros_ec-hwmon-v2-0-1222c5fca0f7@xxxxxxxxxxxxxx Changes in v2: - drop unnecessary range checks (Guenter) - only validate thermal_version during probing - reorder some variable declarations - validate thermal_version directly in cros_ec_hwmon_probe (Mario) - drop return value from probe_temp_sensors as it can't fail anymore - fail with -ENODEV if cmd_readmem is missing to avoid spurious warnings - Link to v1: https://lore.kernel.org/r/20240507-cros_ec-hwmon-v1-0-2c47c5ce8e85@xxxxxxxxxxxxxx --- Thomas Weißschuh (3): platform/chrome: cros_ec_proto: Introduce cros_ec_cmd_readmem() hwmon: add ChromeOS EC driver mfd: cros_ec: Register hardware monitoring subdevice Documentation/hwmon/cros_ec_hwmon.rst | 26 +++ Documentation/hwmon/index.rst | 1 + MAINTAINERS | 8 + drivers/hwmon/Kconfig | 11 ++ drivers/hwmon/Makefile | 1 + drivers/hwmon/cros_ec_hwmon.c | 286 ++++++++++++++++++++++++++++ drivers/mfd/cros_ec_dev.c | 1 + drivers/platform/chrome/cros_ec_proto.c | 27 +++ include/linux/platform_data/cros_ec_proto.h | 2 + 9 files changed, 363 insertions(+) --- base-commit: 2bfcfd584ff5ccc8bb7acde19b42570414bf880b change-id: 20240506-cros_ec-hwmon-24634b07cf6f Best regards, -- Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
