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pmbus: Add driver for Maxim MAX31785 Intelligent Fan Controller The Maxim MAX31785 is a PMBus device providing closed-loop, multi-channel fan management with temperature and remote voltage sensing. It supports various fan control features, including PWM frequency control, temperature hysteresis, dual tachometer measurements, and fan health monitoring. This patch presents a basic driver using only the existing features of the PMBus subsystem. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> [groeck: Modified description to clarify that fan control is not yet provided] Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-11-03 12:53:02 +08:00
Kernel driver max31785
======================
Supported chips:
* Maxim MAX31785, MAX31785A
Prefix: 'max31785' or 'max31785a'
Addresses scanned: -
Datasheet: https://datasheets.maximintegrated.com/en/ds/MAX31785.pdf
Author: Andrew Jeffery <andrew@aj.id.au>
Description
-----------
The Maxim MAX31785 is a PMBus device providing closed-loop, multi-channel fan
management with temperature and remote voltage sensing. Various fan control
features are provided, including PWM frequency control, temperature hysteresis,
dual tachometer measurements, and fan health monitoring.
hwmon: (pmbus/max31785) Add dual tachometer support The dual tachometer feature is implemented in hardware with a TACHSEL input to indicate the rotor under measurement, and exposed on the device by extending the READ_FAN_SPEED_1 word with two extra bytes*. The need to read the non-standard four-byte response leads to a cut-down implementation of i2c_smbus_xfer_emulated() included in the driver. Further, to expose the second rotor tachometer value to userspace the values are exposed through virtual pages. We re-route accesses to FAN_CONFIG_1_2 and READ_FAN_SPEED_1 on pages 23-28 (not defined by the hardware) to the same registers on pages 0-5, and with the latter command we extract the value from the second word of the four-byte response. * The documentation recommends the slower rotor be associated with TACHSEL=0, which corresponds to the first word of the response. The TACHSEL=0 measurement is used by the controller's closed-loop fan management to judge target fan rate. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-11-20 12:42:06 +08:00
For dual-rotor configurations the MAX31785A exposes the second rotor tachometer
readings in attributes fan[5-8]_input. By contrast the MAX31785 only exposes
the slowest rotor measurement, and does so in the fan[1-4]_input attributes.
pmbus: Add driver for Maxim MAX31785 Intelligent Fan Controller The Maxim MAX31785 is a PMBus device providing closed-loop, multi-channel fan management with temperature and remote voltage sensing. It supports various fan control features, including PWM frequency control, temperature hysteresis, dual tachometer measurements, and fan health monitoring. This patch presents a basic driver using only the existing features of the PMBus subsystem. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> [groeck: Modified description to clarify that fan control is not yet provided] Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-11-03 12:53:02 +08:00
Usage Notes
-----------
This driver does not probe for PMBus devices. You will have to instantiate
devices explicitly.
Sysfs attributes
----------------
fan[1-4]_alarm Fan alarm.
fan[1-4]_fault Fan fault.
hwmon: (pmbus/max31785) Add dual tachometer support The dual tachometer feature is implemented in hardware with a TACHSEL input to indicate the rotor under measurement, and exposed on the device by extending the READ_FAN_SPEED_1 word with two extra bytes*. The need to read the non-standard four-byte response leads to a cut-down implementation of i2c_smbus_xfer_emulated() included in the driver. Further, to expose the second rotor tachometer value to userspace the values are exposed through virtual pages. We re-route accesses to FAN_CONFIG_1_2 and READ_FAN_SPEED_1 on pages 23-28 (not defined by the hardware) to the same registers on pages 0-5, and with the latter command we extract the value from the second word of the four-byte response. * The documentation recommends the slower rotor be associated with TACHSEL=0, which corresponds to the first word of the response. The TACHSEL=0 measurement is used by the controller's closed-loop fan management to judge target fan rate. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-11-20 12:42:06 +08:00
fan[1-8]_input Fan RPM. On the MAX31785A, inputs 5-8 correspond to the
second rotor of fans 1-4
hwmon: (pmbus/max31785) Add fan control The implementation makes use of the new fan control virtual registers exposed by the pmbus core. It mixes use of the default implementations with some overrides via the read/write handlers to handle FAN_COMMAND_1 on the MAX31785, whose definition breaks the value range into various control bands dependent on RPM or PWM mode. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-11-20 12:42:04 +08:00
fan[1-4]_target Fan input target
pmbus: Add driver for Maxim MAX31785 Intelligent Fan Controller The Maxim MAX31785 is a PMBus device providing closed-loop, multi-channel fan management with temperature and remote voltage sensing. It supports various fan control features, including PWM frequency control, temperature hysteresis, dual tachometer measurements, and fan health monitoring. This patch presents a basic driver using only the existing features of the PMBus subsystem. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> [groeck: Modified description to clarify that fan control is not yet provided] Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-11-03 12:53:02 +08:00
in[1-6]_crit Critical maximum output voltage
in[1-6]_crit_alarm Output voltage critical high alarm
in[1-6]_input Measured output voltage
in[1-6]_label "vout[18-23]"
in[1-6]_lcrit Critical minimum output voltage
in[1-6]_lcrit_alarm Output voltage critical low alarm
in[1-6]_max Maximum output voltage
in[1-6]_max_alarm Output voltage high alarm
in[1-6]_min Minimum output voltage
in[1-6]_min_alarm Output voltage low alarm
hwmon: (pmbus/max31785) Add fan control The implementation makes use of the new fan control virtual registers exposed by the pmbus core. It mixes use of the default implementations with some overrides via the read/write handlers to handle FAN_COMMAND_1 on the MAX31785, whose definition breaks the value range into various control bands dependent on RPM or PWM mode. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-11-20 12:42:04 +08:00
pwm[1-4] Fan target duty cycle (0..255)
pwm[1-4]_enable 0: Full-speed
1: Manual PWM control
2: Automatic PWM (tach-feedback RPM fan-control)
3: Automatic closed-loop (temp-feedback fan-control)
pmbus: Add driver for Maxim MAX31785 Intelligent Fan Controller The Maxim MAX31785 is a PMBus device providing closed-loop, multi-channel fan management with temperature and remote voltage sensing. It supports various fan control features, including PWM frequency control, temperature hysteresis, dual tachometer measurements, and fan health monitoring. This patch presents a basic driver using only the existing features of the PMBus subsystem. Signed-off-by: Andrew Jeffery <andrew@aj.id.au> [groeck: Modified description to clarify that fan control is not yet provided] Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2017-11-03 12:53:02 +08:00
temp[1-11]_crit Critical high temperature
temp[1-11]_crit_alarm Chip temperature critical high alarm
temp[1-11]_input Measured temperature
temp[1-11]_max Maximum temperature
temp[1-11]_max_alarm Chip temperature high alarm
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