From 3af350929e752fe72f0457033d448bff9aac695a Mon Sep 17 00:00:00 2001 From: Javier Carrasco Date: Tue, 30 Jan 2024 22:06:48 +0100 Subject: hwmon: Add support for Amphenol ChipCap 2 The Amphenol ChipCap 2 is a capacitive polymer humidity and temperature sensor with an integrated EEPROM and minimum/maximum humidity alarms. All device variants offer an I2C interface and depending on the part number, two different output modes: - CC2D: digital output - CC2A: analog (PDM) output This driver adds support for the digital variant (CC2D part numbers), which includes the following part numbers: - non-sleep measurement mode (CC2D23, CC2D25, CC2D33, CC2D35) - sleep measurement mode (CC2D23S, CC2D25S, CC2D33S, CC2D35S) The Chipcap 2 EEPROM can be accessed to configure a series of parameters like the minimum/maximum humidity alarm threshold and hysteresis. The EEPROM is only accessible in the command window after a power-on reset. The default window lasts 10 ms if no Start_CM command is sent. After the command window is finished (either after the mentioned timeout of after a Start_NOM command is sent), the device enters the normal operation mode and makes a first measurement automatically. Unfortunately, the device does not provide any hardware or software reset and therefore the driver must trigger power cycles to enter the command mode. A dedicated, external regulator is required for that. This driver keeps the device off until a measurement or access to the EEPROM is required, making use of the first automatic measurement to avoid different code paths for sleep and non-sleep devices. The minimum and maximum humidity alarms are configured with two registers per alarm: one stores the alarm threshold and the other one keeps the value that turns off the alarm. The alarm signals are only updated when a measurement is carried out. Signed-off-by: Javier Carrasco Link: https://lore.kernel.org/r/20240130-topic-chipcap2-v6-5-260bea05cf9b@gmail.com Signed-off-by: Guenter Roeck --- Documentation/hwmon/chipcap2.rst | 73 ++++++++++++++++++++++++++++++++++++++++ Documentation/hwmon/index.rst | 1 + 2 files changed, 74 insertions(+) create mode 100644 Documentation/hwmon/chipcap2.rst (limited to 'Documentation/hwmon') diff --git a/Documentation/hwmon/chipcap2.rst b/Documentation/hwmon/chipcap2.rst new file mode 100644 index 000000000000..dc165becc64c --- /dev/null +++ b/Documentation/hwmon/chipcap2.rst @@ -0,0 +1,73 @@ +.. SPDX-License-Identifier: GPL-2.0-or-later + +Kernel driver ChipCap2 +====================== + +Supported chips: + + * Amphenol CC2D23, CC2D23S, CC2D25, CC2D25S, CC2D33, CC2D33S, CC2D35, CC2D35S + + Prefix: 'chipcap2' + + Addresses scanned: - + + Datasheet: https://www.amphenol-sensors.com/en/telaire/humidity/527-humidity-sensors/3095-chipcap-2 + +Author: + + - Javier Carrasco + +Description +----------- + +This driver implements support for the Amphenol ChipCap 2, a humidity and +temperature chip family. Temperature is measured in milli degrees celsius, +relative humidity is expressed as a per cent mille. The measurement ranges +are the following: + + - Relative humidity: 0 to 100000 pcm (14-bit resolution) + - Temperature: -40000 to +125000 m°C (14-bit resolution) + +The device communicates with the I2C protocol and uses the I2C address 0x28 +by default. + +Depending on the hardware configuration, up to two humidity alarms to control +minimum and maximum values are provided. Their thresholds and hystersis can be +configured via sysfs. + +Thresholds and hysteris must be provided as a per cent mille. These values +might be truncated to match the 14-bit device resolution (6.1 pcm/LSB) + +Known Issues +------------ + +The driver does not support I2C address and command window length modification. + +sysfs-Interface +--------------- + +The following list includes the sysfs attributes that the driver always provides, +their permissions and a short description: + +=============================== ======= ======================================== +Name Perm Description +=============================== ======= ======================================== +temp1_input: RO temperature input +humidity1_input: RO humidity input +=============================== ======= ======================================== + +The following list includes the sysfs attributes that the driver may provide +depending on the hardware configuration: + +=============================== ======= ======================================== +Name Perm Description +=============================== ======= ======================================== +humidity1_min: RW humidity low limit. Measurements under + this limit trigger a humidity low alarm +humidity1_max: RW humidity high limit. Measurements above + this limit trigger a humidity high alarm +humidity1_min_hyst: RW humidity low hystersis +humidity1_max_hyst: RW humidity high hystersis +humidity1_min_alarm: RO humidity low alarm indicator +humidity1_max_alarm: RO humidity high alarm indicator +=============================== ======= ======================================== diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst index 9ac087dd3e78..0d12254c0f9e 100644 --- a/Documentation/hwmon/index.rst +++ b/Documentation/hwmon/index.rst @@ -51,6 +51,7 @@ Hardware Monitoring Kernel Drivers bel-pfe bpa-rs600 bt1-pvt + chipcap2 coretemp corsair-cpro corsair-psu -- cgit v1.2.3