^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 1) Kernel driver g762
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 2) ==================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 3)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 4) The GMT G762 Fan Speed PWM Controller is connected directly to a fan
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 5) and performs closed-loop or open-loop control of the fan speed. Two
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 6) modes - PWM or DC - are supported by the device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 7)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 8) For additional information, a detailed datasheet is available at
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 9) http://natisbad.org/NAS/ref/GMT_EDS-762_763-080710-0.2.pdf. sysfs
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 10) bindings are described in Documentation/hwmon/sysfs-interface.rst.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 11)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 12) The following entries are available to the user in a subdirectory of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 13) /sys/bus/i2c/drivers/g762/ to control the operation of the device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 14) This can be done manually using the following entries but is usually
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 15) done via a userland daemon like fancontrol.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 16)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 17) Note that those entries do not provide ways to setup the specific
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 18) hardware characteristics of the system (reference clock, pulses per
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 19) fan revolution, ...); Those can be modified via devicetree bindings
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 20) documented in Documentation/devicetree/bindings/hwmon/g762.txt or
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 21) using a specific platform_data structure in board initialization
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 22) file (see include/linux/platform_data/g762.h).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 23)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 24) fan1_target:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 25) set desired fan speed. This only makes sense in closed-loop
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 26) fan speed control (i.e. when pwm1_enable is set to 2).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 27)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 28) fan1_input:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 29) provide current fan rotation value in RPM as reported by
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 30) the fan to the device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 31)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 32) fan1_div:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 33) fan clock divisor. Supported value are 1, 2, 4 and 8.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 34)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 35) fan1_pulses:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 36) number of pulses per fan revolution. Supported values
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 37) are 2 and 4.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 38)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 39) fan1_fault:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 40) reports fan failure, i.e. no transition on fan gear pin for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 41) about 0.7s (if the fan is not voluntarily set off).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 42)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 43) fan1_alarm:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 44) in closed-loop control mode, if fan RPM value is 25% out
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 45) of the programmed value for over 6 seconds 'fan1_alarm' is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 46) set to 1.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 47)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 48) pwm1_enable:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 49) set current fan speed control mode i.e. 1 for manual fan
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 50) speed control (open-loop) via pwm1 described below, 2 for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 51) automatic fan speed control (closed-loop) via fan1_target
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 52) above.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 53)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 54) pwm1_mode:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 55) set or get fan driving mode: 1 for PWM mode, 0 for DC mode.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 56)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 57) pwm1:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 58) get or set PWM fan control value in open-loop mode. This is an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 59) integer value between 0 and 255. 0 stops the fan, 255 makes
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 60) it run at full speed.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 61)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 62) Both in PWM mode ('pwm1_mode' set to 1) and DC mode ('pwm1_mode' set to 0),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 63) when current fan speed control mode is open-loop ('pwm1_enable' set to 1),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 64) the fan speed is programmed by setting a value between 0 and 255 via 'pwm1'
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 65) entry (0 stops the fan, 255 makes it run at full speed). In closed-loop mode
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 66) ('pwm1_enable' set to 2), the expected rotation speed in RPM can be passed to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 67) the chip via 'fan1_target'. In closed-loop mode, the target speed is compared
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 68) with current speed (available via 'fan1_input') by the device and a feedback
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 69) is performed to match that target value. The fan speed value is computed
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 70) based on the parameters associated with the physical characteristics of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 71) system: a reference clock source frequency, a number of pulses per fan
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 72) revolution, etc.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 73)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 74) Note that the driver will update its values at most once per second.
Orange Pi5 kernel
Deprecated Linux kernel 5.10.110 for OrangePi 5/5B/5+ boards
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