hwmon/dme1737: Add documentation

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

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.

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) Super-I/O chips. This chip

features 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 6 fan speeds

fan[1-6]. Additionally, the chip implements 5 PWM outputs pwm[1-3,5-6] for

controlling fan speeds both manually and automatically.

Fan[3-6] and pwm[3,5-6] are optional features and their availability is

dependent on the configuration of the chip. The driver will detect which

features are present during initialization and create the sysfs attributes

accordingly.

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).

L:	netdev@vger.kernel.org

S:	Maintained

DME1737 HARDWARE MONITOR DRIVER

P:	Juerg Haefliger

M:	juergh@gmail.com

L:	lm-sensors@lm-sensors.org

S:	Maintained

DOCBOOK FOR DOCUMENTATION

P:	Randy Dunlap

M:	rdunlap@xenotime.net