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marcus.erl |
Kernel driver fscher
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====================
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Supported chips:
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* Fujitsu-Siemens Hermes chip
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Prefix: 'fscher'
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Addresses scanned: I2C 0x73
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Authors:
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Reinhard Nissl based on work
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from Hermann Jung ,
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Frodo Looijaard ,
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Philip Edelbrock
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Description
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-----------
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This driver implements support for the Fujitsu-Siemens Hermes chip. It is
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described in the 'Register Set Specification BMC Hermes based Systemboard'
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from Fujitsu-Siemens.
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The Hermes chip implements a hardware-based system management, e.g. for
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controlling fan speed and core voltage. There is also a watchdog counter on
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the chip which can trigger an alarm and even shut the system down.
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The chip provides three temperature values (CPU, motherboard and
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auxiliary), three voltage values (+12V, +5V and battery) and three fans
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(power supply, CPU and auxiliary).
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Temperatures are measured in degrees Celsius. The resolution is 1 degree.
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Fan rotation speeds are reported in RPM (rotations per minute). The value
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can be divided by a programmable divider (1, 2 or 4) which is stored on
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the chip.
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Voltage sensors (also known as "in" sensors) report their values in volts.
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All values are reported as final values from the driver. There is no need
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for further calculations.
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Detailed description
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--------------------
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Below you'll find a single line description of all the bit values. With
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this information, you're able to decode e. g. alarms, wdog, etc. To make
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use of the watchdog, you'll need to set the watchdog time and enable the
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watchdog. After that it is necessary to restart the watchdog time within
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the specified period of time, or a system reset will occur.
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* revision
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READING & 0xff = 0x??: HERMES revision identification
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* alarms
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READING & 0x80 = 0x80: CPU throttling active
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READING & 0x80 = 0x00: CPU running at full speed
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READING & 0x10 = 0x10: software event (see control:1)
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READING & 0x10 = 0x00: no software event
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READING & 0x08 = 0x08: watchdog event (see wdog:2)
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READING & 0x08 = 0x00: no watchdog event
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READING & 0x02 = 0x02: thermal event (see temp*:1)
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READING & 0x02 = 0x00: no thermal event
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READING & 0x01 = 0x01: fan event (see fan*:1)
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READING & 0x01 = 0x00: no fan event
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READING & 0x13 ! 0x00: ALERT LED is flashing
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* control
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READING & 0x01 = 0x01: software event
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READING & 0x01 = 0x00: no software event
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WRITING & 0x01 = 0x01: set software event
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WRITING & 0x01 = 0x00: clear software event
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* watchdog_control
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READING & 0x80 = 0x80: power off on watchdog event while thermal event
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READING & 0x80 = 0x00: watchdog power off disabled (just system reset enabled)
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READING & 0x40 = 0x40: watchdog timebase 60 seconds (see also wdog:1)
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READING & 0x40 = 0x00: watchdog timebase 2 seconds
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READING & 0x10 = 0x10: watchdog enabled
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READING & 0x10 = 0x00: watchdog disabled
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WRITING & 0x80 = 0x80: enable "power off on watchdog event while thermal event"
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WRITING & 0x80 = 0x00: disable "power off on watchdog event while thermal event"
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WRITING & 0x40 = 0x40: set watchdog timebase to 60 seconds
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WRITING & 0x40 = 0x00: set watchdog timebase to 2 seconds
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WRITING & 0x20 = 0x20: disable watchdog
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WRITING & 0x10 = 0x10: enable watchdog / restart watchdog time
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* watchdog_state
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READING & 0x02 = 0x02: watchdog system reset occurred
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READING & 0x02 = 0x00: no watchdog system reset occurred
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WRITING & 0x02 = 0x02: clear watchdog event
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* watchdog_preset
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READING & 0xff = 0x??: configured watch dog time in units (see wdog:3 0x40)
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WRITING & 0xff = 0x??: configure watch dog time in units
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* in* (0: +5V, 1: +12V, 2: onboard 3V battery)
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READING: actual voltage value
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* temp*_status (1: CPU sensor, 2: onboard sensor, 3: auxiliary sensor)
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READING & 0x02 = 0x02: thermal event (overtemperature)
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READING & 0x02 = 0x00: no thermal event
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READING & 0x01 = 0x01: sensor is working
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READING & 0x01 = 0x00: sensor is faulty
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WRITING & 0x02 = 0x02: clear thermal event
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* temp*_input (1: CPU sensor, 2: onboard sensor, 3: auxiliary sensor)
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READING: actual temperature value
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* fan*_status (1: power supply fan, 2: CPU fan, 3: auxiliary fan)
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READING & 0x04 = 0x04: fan event (fan fault)
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READING & 0x04 = 0x00: no fan event
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WRITING & 0x04 = 0x04: clear fan event
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* fan*_div (1: power supply fan, 2: CPU fan, 3: auxiliary fan)
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Divisors 2,4 and 8 are supported, both for reading and writing
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* fan*_pwm (1: power supply fan, 2: CPU fan, 3: auxiliary fan)
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READING & 0xff = 0x00: fan may be switched off
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READING & 0xff = 0x01: fan must run at least at minimum speed (supply: 6V)
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READING & 0xff = 0xff: fan must run at maximum speed (supply: 12V)
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READING & 0xff = 0x??: fan must run at least at given speed (supply: 6V..12V)
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WRITING & 0xff = 0x00: fan may be switched off
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WRITING & 0xff = 0x01: fan must run at least at minimum speed (supply: 6V)
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WRITING & 0xff = 0xff: fan must run at maximum speed (supply: 12V)
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WRITING & 0xff = 0x??: fan must run at least at given speed (supply: 6V..12V)
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* fan*_input (1: power supply fan, 2: CPU fan, 3: auxiliary fan)
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READING: actual RPM value
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Limitations
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-----------
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* Measuring fan speed
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It seems that the chip counts "ripples" (typical fans produce 2 ripples per
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rotation while VERAX fans produce 18) in a 9-bit register. This register is
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read out every second, then the ripple prescaler (2, 4 or 8) is applied and
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the result is stored in the 8 bit output register. Due to the limitation of
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the counting register to 9 bits, it is impossible to measure a VERAX fan
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properly (even with a prescaler of 8). At its maximum speed of 3500 RPM the
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fan produces 1080 ripples per second which causes the counting register to
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overflow twice, leading to only 186 RPM.
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* Measuring input voltages
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in2 ("battery") reports the voltage of the onboard lithium battery and not
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+3.3V from the power supply.
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* Undocumented features
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Fujitsu-Siemens Computers has not documented all features of the chip so
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far. Their software, System Guard, shows that there are a still some
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features which cannot be controlled by this implementation.
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