hwmon: (dme1737) Skip detection if forced

[mirror_ubuntu-artful-kernel.git] / Documentation / hwmon / dme1737

Kernel driver dme1737
=====================

Supported chips:
  * SMSC DME1737 and compatibles (like Asus A8000)
    Prefix: 'dme1737'
    Addresses scanned: I2C 0x2c, 0x2d, 0x2e
    Datasheet: Provided by SMSC upon request and under NDA
  * SMSC SCH3112, SCH3114, SCH3116
    Prefix: 'sch311x'
    Addresses scanned: none, address read from Super-I/O config space
    Datasheet: http://www.nuhorizons.com/FeaturedProducts/Volume1/SMSC/311x.pdf

Authors:
    Juerg Haefliger <juergh@gmail.com>


Module Parameters
-----------------

* force_start: bool	Enables the monitoring of voltage, fan and temp inputs
			and PWM output control functions. Using this parameter
			shouldn't be required since the BIOS usually takes care
			of this.
* probe_all_addr: bool	Include non-standard LPC addresses 0x162e and 0x164e
			when probing for ISA devices. This is required for the
			following boards:
			- VIA EPIA SN18000

Note that there is no need to use this parameter if the driver loads without
complaining. The driver will say so if it is necessary.


Description
-----------

This driver implements support for the hardware monitoring capabilities of the
SMSC DME1737 and Asus A8000 (which are the same) and SMSC SCH311x Super-I/O
chips. These chips feature monitoring of 3 temp sensors temp[1-3] (2 remote
diodes and 1 internal), 7 voltages in[0-6] (6 external and 1 internal) and up
to 6 fan speeds fan[1-6]. Additionally, the chips implement up to 5 PWM
outputs pwm[1-3,5-6] for controlling fan speeds both manually and
automatically.

For the DME1737 and A8000, fan[1-2] and pwm[1-2] are always present. Fan[3-6]
and pwm[3,5-6] are optional features and their availability depends on the
configuration of the chip. The driver will detect which features are present
during initialization and create the sysfs attributes accordingly.

For the SCH311x, fan[1-3] and pwm[1-3] are always present and fan[4-6] and
pwm[5-6] don't exist.

The hardware monitoring features of the DME1737 and A8000 are only accessible
via SMBus, while the SCH311x only provides access via the ISA bus. The driver
will therefore register itself as an I2C client driver if it detects a DME1737
or A8000 and as a platform driver if it detects a SCH311x chip.


Voltage Monitoring
------------------

The voltage inputs are sampled with 12-bit resolution and have internal
scaling resistors. The values returned by the driver therefore reflect true
millivolts and don't need scaling. The voltage inputs are mapped as follows
(the last column indicates the input ranges):

	in0: +5VTR	(+5V standby)		0V - 6.64V
	in1: Vccp	(processor core)	0V - 3V
	in2: VCC	(internal +3.3V)	0V - 4.38V
	in3: +5V				0V - 6.64V
	in4: +12V				0V - 16V
	in5: VTR	(+3.3V standby)		0V - 4.38V
	in6: Vbat	(+3.0V)			0V - 4.38V

Each voltage input has associated min and max limits which trigger an alarm
when crossed.


Temperature Monitoring
----------------------

Temperatures are measured with 12-bit resolution and reported in millidegree
Celsius. The chip also features offsets for all 3 temperature inputs which -
when programmed - get added to the input readings. The chip does all the
scaling by itself and the driver therefore reports true temperatures that don't
need any user-space adjustments. The temperature inputs are mapped as follows
(the last column indicates the input ranges):

	temp1: Remote diode 1 (3904 type) temperature	-127C - +127C
	temp2: DME1737 internal temperature		-127C - +127C
	temp3: Remote diode 2 (3904 type) temperature	-127C - +127C

Each temperature input has associated min and max limits which trigger an alarm
when crossed. Additionally, each temperature input has a fault attribute that
returns 1 when a faulty diode or an unconnected input is detected and 0
otherwise.


Fan Monitoring
--------------

Fan RPMs are measured with 16-bit resolution. The chip provides inputs for 6
fan tachometers. All 6 inputs have an associated min limit which triggers an
alarm when crossed. Fan inputs 1-4 provide type attributes that need to be set
to the number of pulses per fan revolution that the connected tachometer
generates. Supported values are 1, 2, and 4. Fan inputs 5-6 only support fans
that generate 2 pulses per revolution. Fan inputs 5-6 also provide a max
attribute that needs to be set to the maximum attainable RPM (fan at 100% duty-
cycle) of the input. The chip adjusts the sampling rate based on this value.


PWM Output Control
------------------

This chip features 5 PWM outputs. PWM outputs 1-3 are associated with fan
inputs 1-3 and PWM outputs 5-6 are associated with fan inputs 5-6. PWM outputs
1-3 can be configured to operate either in manual or automatic mode by setting
the appropriate enable attribute accordingly. PWM outputs 5-6 can only operate
in manual mode, their enable attributes are therefore read-only. When set to
manual mode, the fan speed is set by writing the duty-cycle value to the
appropriate PWM attribute. In automatic mode, the PWM attribute returns the
current duty-cycle as set by the fan controller in the chip. All PWM outputs
support the setting of the output frequency via the freq attribute.

In automatic mode, the chip supports the setting of the PWM ramp rate which
defines how fast the PWM output is adjusting to changes of the associated
temperature input. Associating PWM outputs to temperature inputs is done via
temperature zones. The chip features 3 zones whose assignments to temperature
inputs is static and determined during initialization. These assignments can
be retrieved via the zone[1-3]_auto_channels_temp attributes. Each PWM output
is assigned to one (or hottest of multiple) temperature zone(s) through the
pwm[1-3]_auto_channels_zone attributes. Each PWM output has 3 distinct output
duty-cycles: full, low, and min. Full is internally hard-wired to 255 (100%)
and low and min can be programmed via pwm[1-3]_auto_point1_pwm and
pwm[1-3]_auto_pwm_min, respectively. The thermal thresholds of the zones are
programmed via zone[1-3]_auto_point[1-3]_temp and
zone[1-3]_auto_point1_temp_hyst:

	pwm[1-3]_auto_point2_pwm	full-speed duty-cycle (255, i.e., 100%)
	pwm[1-3]_auto_point1_pwm	low-speed duty-cycle
	pwm[1-3]_auto_pwm_min		min-speed duty-cycle

	zone[1-3]_auto_point3_temp	full-speed temp (all outputs)
	zone[1-3]_auto_point2_temp	full-speed temp
	zone[1-3]_auto_point1_temp	low-speed temp
	zone[1-3]_auto_point1_temp_hyst	min-speed temp

The chip adjusts the output duty-cycle linearly in the range of auto_point1_pwm
to auto_point2_pwm if the temperature of the associated zone is between
auto_point1_temp and auto_point2_temp. If the temperature drops below the
auto_point1_temp_hyst value, the output duty-cycle is set to the auto_pwm_min
value which only supports two values: 0 or auto_point1_pwm. That means that the
fan either turns completely off or keeps spinning with the low-speed
duty-cycle. If any of the temperatures rise above the auto_point3_temp value,
all PWM outputs are set to 100% duty-cycle.

Following is another representation of how the chip sets the output duty-cycle
based on the temperature of the associated thermal zone:

			Duty-Cycle	Duty-Cycle
	Temperature	Rising Temp	Falling Temp
	-----------	-----------	------------
	full-speed	full-speed	full-speed

			< linearly adjusted duty-cycle >

	low-speed	low-speed	low-speed
			min-speed	low-speed
	min-speed	min-speed	min-speed
			min-speed	min-speed


Sysfs Attributes
----------------

Following is a list of all sysfs attributes that the driver provides, their
permissions and a short description:

Name				Perm	Description
----				----	-----------
cpu0_vid			RO	CPU core reference voltage in
					millivolts.
vrm				RW	Voltage regulator module version
					number.

in[0-6]_input			RO	Measured voltage in millivolts.
in[0-6]_min			RW	Low limit for voltage input.
in[0-6]_max			RW	High limit for voltage input.
in[0-6]_alarm			RO	Voltage input alarm. Returns 1 if
					voltage input is or went outside the
					associated min-max range, 0 otherwise.

temp[1-3]_input			RO	Measured temperature in millidegree
					Celsius.
temp[1-3]_min			RW	Low limit for temp input.
temp[1-3]_max			RW	High limit for temp input.
temp[1-3]_offset		RW	Offset for temp input. This value will
					be added by the chip to the measured
					temperature.
temp[1-3]_alarm			RO	Alarm for temp input. Returns 1 if temp
					input is or went outside the associated
					min-max range, 0 otherwise.
temp[1-3]_fault			RO	Temp input fault. Returns 1 if the chip
					detects a faulty thermal diode or an
					unconnected temp input, 0 otherwise.

zone[1-3]_auto_channels_temp	RO	Temperature zone to temperature input
					mapping. This attribute is a bitfield
					and supports the following values:
						1: temp1
						2: temp2
						4: temp3
zone[1-3]_auto_point1_temp_hyst	RW	Auto PWM temp point1 hysteresis. The
					output of the corresponding PWM is set
					to the pwm_auto_min value if the temp
					falls below the auto_point1_temp_hyst
					value.
zone[1-3]_auto_point[1-3]_temp	RW	Auto PWM temp points. Auto_point1 is
					the low-speed temp, auto_point2 is the
					full-speed temp, and auto_point3 is the
					temp at which all PWM outputs are set
					to full-speed (100% duty-cycle).

fan[1-6]_input			RO	Measured fan speed in RPM.
fan[1-6]_min			RW	Low limit for fan input.
fan[1-6]_alarm			RO	Alarm for fan input. Returns 1 if fan
					input is or went below the associated
					min value, 0 otherwise.
fan[1-4]_type			RW	Type of attached fan. Expressed in
					number of pulses per revolution that
					the fan generates. Supported values are
					1, 2, and 4.
fan[5-6]_max			RW	Max attainable RPM at 100% duty-cycle.
					Required for chip to adjust the
					sampling rate accordingly.

pmw[1-3,5-6]			RO/RW	Duty-cycle of PWM output. Supported
					values are 0-255 (0%-100%). Only
					writeable if the associated PWM is in
					manual mode.
pwm[1-3]_enable			RW	Enable of PWM outputs 1-3. Supported
					values are:
						 0: turned off (output @ 100%)
						 1: manual mode
						 2: automatic mode
pwm[5-6]_enable			RO	Enable of PWM outputs 5-6. Always
					returns 1 since these 2 outputs are
					hard-wired to manual mode.
pmw[1-3,5-6]_freq		RW	Frequency of PWM output. Supported
					values are in the range 11Hz-30000Hz
					(default is 25000Hz).
pmw[1-3]_ramp_rate		RW	Ramp rate of PWM output. Determines how
					fast the PWM duty-cycle will change
					when the PWM is in automatic mode.
					Expressed in ms per PWM step. Supported
					values are in the range 0ms-206ms
					(default is 0, which means the duty-
					cycle changes instantly).
pwm[1-3]_auto_channels_zone	RW	PWM output to temperature zone mapping.
					This attribute is a bitfield and
					supports the following values:
						1: zone1
						2: zone2
						4: zone3
						6: highest of zone[2-3]
						7: highest of zone[1-3]
pwm[1-3]_auto_pwm_min		RW	Auto PWM min pwm. Minimum PWM duty-
					cycle. Supported values are 0 or
					auto_point1_pwm.
pwm[1-3]_auto_point1_pwm	RW	Auto PWM pwm point. Auto_point1 is the
					low-speed duty-cycle.
pwm[1-3]_auto_point2_pwm	RO	Auto PWM pwm point. Auto_point2 is the
					full-speed duty-cycle which is hard-
					wired to 255 (100% duty-cycle).