[PATCH] I2C: W83792D documentation 3/3
This patch adds documentation entry for W83792D chip. Signed-off-by: Rudolf Marek <r.marek@sh.cvut.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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R.Marek@sh.cvut.cz
Greg Kroah-Hartman
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Kernel driver w83792d
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=====================
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Supported chips:
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* Winbond W83792D
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Prefix: 'w83792d'
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Addresses scanned: I2C 0x2c - 0x2f
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Datasheet: http://www.winbond.com.tw/E-WINBONDHTM/partner/PDFresult.asp?Pname=1035
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Author: Chunhao Huang
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Contact: DZShen <DZShen@Winbond.com.tw>
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Module Parameters
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-----------------
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* init int
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(default 1)
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Use 'init=0' to bypass initializing the chip.
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Try this if your computer crashes when you load the module.
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* force_subclients=bus,caddr,saddr,saddr
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This is used to force the i2c addresses for subclients of
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a certain chip. Example usage is `force_subclients=0,0x2f,0x4a,0x4b'
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to force the subclients of chip 0x2f on bus 0 to i2c addresses
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0x4a and 0x4b.
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Description
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-----------
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This driver implements support for the Winbond W83792AD/D.
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Detection of the chip can sometimes be foiled because it can be in an
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internal state that allows no clean access (Bank with ID register is not
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currently selected). If you know the address of the chip, use a 'force'
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parameter; this will put it into a more well-behaved state first.
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The driver implements three temperature sensors, seven fan rotation speed
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sensors, nine voltage sensors, and two automatic fan regulation
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strategies called: Smart Fan I (Thermal Cruise mode) and Smart Fan II.
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Automatic fan control mode is possible only for fan1-fan3. Fan4-fan7 can run
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synchronized with selected fan (fan1-fan3). This functionality and manual PWM
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control for fan4-fan7 is not yet implemented.
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Temperatures are measured in degrees Celsius and measurement resolution is 1
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degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when
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the temperature gets higher than the Overtemperature Shutdown value; it stays
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on until the temperature falls below the Hysteresis value.
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Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
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triggered if the rotation speed has dropped below a programmable limit. Fan
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readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
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128) to give the readings more range or accuracy.
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Voltage sensors (also known as IN sensors) report their values in millivolts.
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An alarm is triggered if the voltage has crossed a programmable minimum
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or maximum limit.
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Alarms are provided as output from "realtime status register". Following bits
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are defined:
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bit - alarm on:
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0 - in0
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1 - in1
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2 - temp1
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3 - temp2
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4 - temp3
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5 - fan1
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6 - fan2
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7 - fan3
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8 - in2
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9 - in3
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10 - in4
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11 - in5
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12 - in6
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13 - VID change
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14 - chassis
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15 - fan7
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16 - tart1
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17 - tart2
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18 - tart3
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19 - in7
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20 - in8
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21 - fan4
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22 - fan5
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23 - fan6
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Tart will be asserted while target temperature cannot be achieved after 3 minutes
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of full speed rotation of corresponding fan.
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In addition to the alarms described above, there is a CHAS alarm on the chips
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which triggers if your computer case is open (This one is latched, contrary
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to realtime alarms).
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The chips only update values each 3 seconds; reading them more often will
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do no harm, but will return 'old' values.
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W83792D PROBLEMS
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----------------
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Known problems:
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- This driver is only for Winbond W83792D C version device, there
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are also some motherboards with B version W83792D device. The
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calculation method to in6-in7(measured value, limits) is a little
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different between C and B version. C or B version can be identified
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by CR[0x49h].
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- The function of vid and vrm has not been finished, because I'm NOT
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very familiar with them. Adding support is welcome.
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- The function of chassis open detection needs more tests.
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- If you have ASUS server board and chip was not found: Then you will
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need to upgrade to latest (or beta) BIOS. If it does not help please
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contact us.
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Fan control
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-----------
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Manual mode
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-----------
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Works as expected. You just need to specify desired PWM/DC value (fan speed)
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in appropriate pwm# file.
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Thermal cruise
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--------------
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In this mode, W83792D provides the Smart Fan system to automatically control
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fan speed to keep the temperatures of CPU and the system within specific
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range. At first a wanted temperature and interval must be set. This is done
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via thermal_cruise# file. The tolerance# file serves to create T +- tolerance
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interval. The fan speed will be lowered as long as the current temperature
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remains below the thermal_cruise# +- tolerance# value. Once the temperature
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exceeds the high limit (T+tolerance), the fan will be turned on with a
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specific speed set by pwm# and automatically controlled its PWM duty cycle
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with the temperature varying. Three conditions may occur:
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(1) If the temperature still exceeds the high limit, PWM duty
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cycle will increase slowly.
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(2) If the temperature goes below the high limit, but still above the low
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limit (T-tolerance), the fan speed will be fixed at the current speed because
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the temperature is in the target range.
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(3) If the temperature goes below the low limit, PWM duty cycle will decrease
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slowly to 0 or a preset stop value until the temperature exceeds the low
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limit. (The preset stop value handling is not yet implemented in driver)
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Smart Fan II
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------------
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W83792D also provides a special mode for fan. Four temperature points are
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available. When related temperature sensors detects the temperature in preset
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temperature region (sf2_point@_fan# +- tolerance#) it will cause fans to run
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on programmed value from sf2_level@_fan#. You need to set four temperatures
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for each fan.
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/sys files
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----------
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pwm[1-3] - this file stores PWM duty cycle or DC value (fan speed) in range:
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0 (stop) to 255 (full)
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pwm[1-3]_enable - this file controls mode of fan/temperature control:
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* 0 Disabled
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* 1 Manual mode
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* 2 Smart Fan II
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* 3 Thermal Cruise
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pwm[1-3]_mode - Select PWM of DC mode
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* 0 DC
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* 1 PWM
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thermal_cruise[1-3] - Selects the desired temperature for cruise (degC)
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tolerance[1-3] - Value in degrees of Celsius (degC) for +- T
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sf2_point[1-4]_fan[1-3] - four temperature points for each fan for Smart Fan II
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sf2_level[1-3]_fan[1-3] - three PWM/DC levels for each fan for Smart Fan II
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