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Diffstat (limited to 'kernel/Documentation/hwmon/w83792d')
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diff --git a/kernel/Documentation/hwmon/w83792d b/kernel/Documentation/hwmon/w83792d new file mode 100644 index 000000000..53f7b6866 --- /dev/null +++ b/kernel/Documentation/hwmon/w83792d @@ -0,0 +1,173 @@ +Kernel driver w83792d +===================== + +Supported chips: + * Winbond W83792D + Prefix: 'w83792d' + Addresses scanned: I2C 0x2c - 0x2f + Datasheet: http://www.winbond.com.tw + +Author: Shane Huang (Winbond) + + +Module Parameters +----------------- + +* init int + (default 1) + Use 'init=0' to bypass initializing the chip. + Try this if your computer crashes when you load the module. + +* force_subclients=bus,caddr,saddr,saddr + This is used to force the i2c addresses for subclients of + a certain chip. Example usage is `force_subclients=0,0x2f,0x4a,0x4b' + to force the subclients of chip 0x2f on bus 0 to i2c addresses + 0x4a and 0x4b. + + +Description +----------- + +This driver implements support for the Winbond W83792AD/D. + +Detection of the chip can sometimes be foiled because it can be in an +internal state that allows no clean access (Bank with ID register is not +currently selected). If you know the address of the chip, use a 'force' +parameter; this will put it into a more well-behaved state first. + +The driver implements three temperature sensors, seven fan rotation speed +sensors, nine voltage sensors, and two automatic fan regulation +strategies called: Smart Fan I (Thermal Cruise mode) and Smart Fan II. +Automatic fan control mode is possible only for fan1-fan3. Fan4-fan7 can run +synchronized with selected fan (fan1-fan3). This functionality and manual PWM +control for fan4-fan7 is not yet implemented. + +Temperatures are measured in degrees Celsius and measurement resolution is 1 +degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when +the temperature gets higher than the Overtemperature Shutdown value; it stays +on until the temperature falls below the Hysteresis value. + +Fan rotation speeds are reported in RPM (rotations per minute). An alarm is +triggered if the rotation speed has dropped below a programmable limit. Fan +readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or +128) to give the readings more range or accuracy. + +Voltage sensors (also known as IN sensors) report their values in millivolts. +An alarm is triggered if the voltage has crossed a programmable minimum +or maximum limit. + +Alarms are provided as output from "realtime status register". Following bits +are defined: + +bit - alarm on: +0 - in0 +1 - in1 +2 - temp1 +3 - temp2 +4 - temp3 +5 - fan1 +6 - fan2 +7 - fan3 +8 - in2 +9 - in3 +10 - in4 +11 - in5 +12 - in6 +13 - VID change +14 - chassis +15 - fan7 +16 - tart1 +17 - tart2 +18 - tart3 +19 - in7 +20 - in8 +21 - fan4 +22 - fan5 +23 - fan6 + +Tart will be asserted while target temperature cannot be achieved after 3 minutes +of full speed rotation of corresponding fan. + +In addition to the alarms described above, there is a CHAS alarm on the chips +which triggers if your computer case is open (This one is latched, contrary +to realtime alarms). + +The chips only update values each 3 seconds; reading them more often will +do no harm, but will return 'old' values. + + +W83792D PROBLEMS +---------------- +Known problems: + - This driver is only for Winbond W83792D C version device, there + are also some motherboards with B version W83792D device. The + calculation method to in6-in7(measured value, limits) is a little + different between C and B version. C or B version can be identified + by CR[0x49h]. + - The function of vid and vrm has not been finished, because I'm NOT + very familiar with them. Adding support is welcome. + - The function of chassis open detection needs more tests. + - If you have ASUS server board and chip was not found: Then you will + need to upgrade to latest (or beta) BIOS. If it does not help please + contact us. + +Fan control +----------- + +Manual mode +----------- + +Works as expected. You just need to specify desired PWM/DC value (fan speed) +in appropriate pwm# file. + +Thermal cruise +-------------- + +In this mode, W83792D provides the Smart Fan system to automatically control +fan speed to keep the temperatures of CPU and the system within specific +range. At first a wanted temperature and interval must be set. This is done +via thermal_cruise# file. The tolerance# file serves to create T +- tolerance +interval. The fan speed will be lowered as long as the current temperature +remains below the thermal_cruise# +- tolerance# value. Once the temperature +exceeds the high limit (T+tolerance), the fan will be turned on with a +specific speed set by pwm# and automatically controlled its PWM duty cycle +with the temperature varying. Three conditions may occur: + +(1) If the temperature still exceeds the high limit, PWM duty +cycle will increase slowly. + +(2) If the temperature goes below the high limit, but still above the low +limit (T-tolerance), the fan speed will be fixed at the current speed because +the temperature is in the target range. + +(3) If the temperature goes below the low limit, PWM duty cycle will decrease +slowly to 0 or a preset stop value until the temperature exceeds the low +limit. (The preset stop value handling is not yet implemented in driver) + +Smart Fan II +------------ + +W83792D also provides a special mode for fan. Four temperature points are +available. When related temperature sensors detects the temperature in preset +temperature region (sf2_point@_fan# +- tolerance#) it will cause fans to run +on programmed value from sf2_level@_fan#. You need to set four temperatures +for each fan. + + +/sys files +---------- + +pwm[1-3] - this file stores PWM duty cycle or DC value (fan speed) in range: + 0 (stop) to 255 (full) +pwm[1-3]_enable - this file controls mode of fan/temperature control: + * 0 Disabled + * 1 Manual mode + * 2 Smart Fan II + * 3 Thermal Cruise +pwm[1-3]_mode - Select PWM of DC mode + * 0 DC + * 1 PWM +thermal_cruise[1-3] - Selects the desired temperature for cruise (degC) +tolerance[1-3] - Value in degrees of Celsius (degC) for +- T +sf2_point[1-4]_fan[1-3] - four temperature points for each fan for Smart Fan II +sf2_level[1-3]_fan[1-3] - three PWM/DC levels for each fan for Smart Fan II |