hwmon/dme1737: Add documentation

Add documentation for the new SMSC DME1737 driver.

Signed-off-by: Juerg Haefliger <juergh at gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

1 files changed, 257 insertions, 0 deletions

diff --git a/Documentation/hwmon/dme1737 b/Documentation/hwmon/dme1737
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+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).