1Kernel driver w83792d
2=====================
3
4Supported chips:
5  * Winbond W83792D
6    Prefix: 'w83792d'
7    Addresses scanned: I2C 0x2c - 0x2f
8    Datasheet: http://www.winbond.com.tw
9
10Author: Shane Huang (Winbond)
11
12
13Module Parameters
14-----------------
15
16* init int
17  (default 1)
18  Use 'init=0' to bypass initializing the chip.
19  Try this if your computer crashes when you load the module.
20
21* force_subclients=bus,caddr,saddr,saddr
22  This is used to force the i2c addresses for subclients of
23  a certain chip. Example usage is `force_subclients=0,0x2f,0x4a,0x4b'
24  to force the subclients of chip 0x2f on bus 0 to i2c addresses
25  0x4a and 0x4b.
26
27
28Description
29-----------
30
31This driver implements support for the Winbond W83792AD/D.
32
33Detection of the chip can sometimes be foiled because it can be in an
34internal state that allows no clean access (Bank with ID register is not
35currently selected). If you know the address of the chip, use a 'force'
36parameter; this will put it into a more well-behaved state first.
37
38The driver implements three temperature sensors, seven fan rotation speed
39sensors, nine voltage sensors, and two automatic fan regulation
40strategies called: Smart Fan I (Thermal Cruise mode) and Smart Fan II.
41Automatic fan control mode is possible only for fan1-fan3. Fan4-fan7 can run
42synchronized with selected fan (fan1-fan3). This functionality and manual PWM
43control for fan4-fan7 is not yet implemented.
44
45Temperatures are measured in degrees Celsius and measurement resolution is 1
46degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when
47the temperature gets higher than the Overtemperature Shutdown value; it stays
48on until the temperature falls below the Hysteresis value.
49
50Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
51triggered if the rotation speed has dropped below a programmable limit. Fan
52readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
53128) to give the readings more range or accuracy.
54
55Voltage sensors (also known as IN sensors) report their values in millivolts.
56An alarm is triggered if the voltage has crossed a programmable minimum
57or maximum limit.
58
59Alarms are provided as output from "realtime status register". Following bits
60are defined:
61
62bit - alarm on:
630  - in0
641  - in1
652  - temp1
663  - temp2
674  - temp3
685  - fan1
696  - fan2
707  - fan3
718  - in2
729  - in3
7310 - in4
7411 - in5
7512 - in6
7613 - VID change
7714 - chassis
7815 - fan7
7916 - tart1
8017 - tart2
8118 - tart3
8219 - in7
8320 - in8
8421 - fan4
8522 - fan5
8623 - fan6
87
88Tart will be asserted while target temperature cannot be achieved after 3 minutes
89of full speed rotation of corresponding fan.
90
91In addition to the alarms described above, there is a CHAS alarm on the chips
92which triggers if your computer case is open (This one is latched, contrary
93to realtime alarms).
94
95The chips only update values each 3 seconds; reading them more often will
96do no harm, but will return 'old' values.
97
98
99W83792D PROBLEMS
100----------------
101Known problems:
102	- This driver is only for Winbond W83792D C version device, there
103	  are also some motherboards with B version W83792D device. The
104	  calculation method to in6-in7(measured value, limits) is a little
105	  different between C and B version. C or B version can be identified
106	  by CR[0x49h].
107	- The function of vid and vrm has not been finished, because I'm NOT
108	  very familiar with them. Adding support is welcome.
109 	- The function of chassis open detection needs more tests.
110	- If you have ASUS server board and chip was not found: Then you will
111	  need to upgrade to latest (or beta) BIOS. If it does not help please
112	  contact us.
113
114Fan control
115-----------
116
117Manual mode
118-----------
119
120Works as expected. You just need to specify desired PWM/DC value (fan speed)
121in appropriate pwm# file.
122
123Thermal cruise
124--------------
125
126In this mode, W83792D provides the Smart Fan system to automatically control
127fan speed to keep the temperatures of CPU and the system within specific
128range. At first a wanted temperature and interval must be set. This is done
129via thermal_cruise# file. The tolerance# file serves to create T +- tolerance
130interval. The fan speed will be lowered as long as the current temperature
131remains below the thermal_cruise# +- tolerance# value. Once the temperature
132exceeds the high limit (T+tolerance), the fan will be turned on with a
133specific speed set by pwm# and automatically controlled its PWM duty cycle
134with the temperature varying. Three conditions may occur:
135
136(1) If the temperature still exceeds the high limit, PWM duty
137cycle will increase slowly.
138
139(2) If the temperature goes below the high limit, but still above the low
140limit (T-tolerance), the fan speed will be fixed at the current speed because
141the temperature is in the target range.
142
143(3) If the temperature goes below the low limit, PWM duty cycle will decrease
144slowly to 0 or a preset stop value until the temperature exceeds the low
145limit. (The preset stop value handling is not yet implemented in driver)
146
147Smart Fan II
148------------
149
150W83792D also provides a special mode for fan. Four temperature points are
151available. When related temperature sensors detects the temperature in preset
152temperature region (sf2_point@_fan# +- tolerance#) it will cause fans to run
153on programmed value from sf2_level@_fan#. You need to set four temperatures
154for each fan.
155
156
157/sys files
158----------
159
160pwm[1-3] - this file stores PWM duty cycle or DC value (fan speed) in range:
161	0 (stop) to 255 (full)
162pwm[1-3]_enable - this file controls mode of fan/temperature control:
163            * 0 Disabled
164            * 1 Manual mode
165            * 2 Smart Fan II
166            * 3 Thermal Cruise
167pwm[1-3]_mode - Select PWM of DC mode
168            * 0 DC
169            * 1 PWM
170thermal_cruise[1-3] - Selects the desired temperature for cruise (degC)
171tolerance[1-3] - Value in degrees of Celsius (degC) for +- T
172sf2_point[1-4]_fan[1-3] - four temperature points for each fan for Smart Fan II
173sf2_level[1-3]_fan[1-3] - three PWM/DC levels for each fan for Smart Fan II
174