1 Kernel driver w83792d
2 =====================
3
4 Supported chips:
5 * Winbond W83792D
6 Prefix: 'w83792d'
7 Addresses scanned: I2C 0x2c - 0x2f
8 Datasheet: http://www.winbond.com.tw/E-WINBONDHTM/partner/PDFresult.asp?Pname=1035
9
10 Author: Chunhao Huang
11 Contact: DZShen <DZShen@Winbond.com.tw>
12
13
14 Module Parameters
15 -----------------
16
17 * init int
18 (default 1)
19 Use 'init=0' to bypass initializing the chip.
20 Try this if your computer crashes when you load the module.
21
22 * force_subclients=bus,caddr,saddr,saddr
23 This is used to force the i2c addresses for subclients of
24 a certain chip. Example usage is `force_subclients=0,0x2f,0x4a,0x4b'
25 to force the subclients of chip 0x2f on bus 0 to i2c addresses
26 0x4a and 0x4b.
27
28
29 Description
30 -----------
31
32 This driver implements support for the Winbond W83792AD/D.
33
34 Detection of the chip can sometimes be foiled because it can be in an
35 internal state that allows no clean access (Bank with ID register is not
36 currently selected). If you know the address of the chip, use a 'force'
37 parameter; this will put it into a more well-behaved state first.
38
39 The driver implements three temperature sensors, seven fan rotation speed
40 sensors, nine voltage sensors, and two automatic fan regulation
41 strategies called: Smart Fan I (Thermal Cruise mode) and Smart Fan II.
42 Automatic fan control mode is possible only for fan1-fan3. Fan4-fan7 can run
43 synchronized with selected fan (fan1-fan3). This functionality and manual PWM
44 control for fan4-fan7 is not yet implemented.
45
46 Temperatures are measured in degrees Celsius and measurement resolution is 1
47 degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when
48 the temperature gets higher than the Overtemperature Shutdown value; it stays
49 on until the temperature falls below the Hysteresis value.
50
51 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
52 triggered if the rotation speed has dropped below a programmable limit. Fan
53 readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
54 128) to give the readings more range or accuracy.
55
56 Voltage sensors (also known as IN sensors) report their values in millivolts.
57 An alarm is triggered if the voltage has crossed a programmable minimum
58 or maximum limit.
59
60 Alarms are provided as output from "realtime status register". Following bits
61 are defined:
62
63 bit - alarm on:
64 0 - in0
65 1 - in1
66 2 - temp1
67 3 - temp2
68 4 - temp3
69 5 - fan1
70 6 - fan2
71 7 - fan3
72 8 - in2
73 9 - in3
74 10 - in4
75 11 - in5
76 12 - in6
77 13 - VID change
78 14 - chassis
79 15 - fan7
80 16 - tart1
81 17 - tart2
82 18 - tart3
83 19 - in7
84 20 - in8
85 21 - fan4
86 22 - fan5
87 23 - fan6
88
89 Tart will be asserted while target temperature cannot be achieved after 3 minutes
90 of full speed rotation of corresponding fan.
91
92 In addition to the alarms described above, there is a CHAS alarm on the chips
93 which triggers if your computer case is open (This one is latched, contrary
94 to realtime alarms).
95
96 The chips only update values each 3 seconds; reading them more often will
97 do no harm, but will return 'old' values.
98
99
100 W83792D PROBLEMS
101 ----------------
102 Known problems:
103 - This driver is only for Winbond W83792D C version device, there
104 are also some motherboards with B version W83792D device. The
105 calculation method to in6-in7(measured value, limits) is a little
106 different between C and B version. C or B version can be identified
107 by CR[0x49h].
108 - The function of vid and vrm has not been finished, because I'm NOT
109 very familiar with them. Adding support is welcome.
110 - The function of chassis open detection needs more tests.
111 - If you have ASUS server board and chip was not found: Then you will
112 need to upgrade to latest (or beta) BIOS. If it does not help please
113 contact us.
114
115 Fan control
116 -----------
117
118 Manual mode
119 -----------
120
121 Works as expected. You just need to specify desired PWM/DC value (fan speed)
122 in appropriate pwm# file.
123
124 Thermal cruise
125 --------------
126
127 In this mode, W83792D provides the Smart Fan system to automatically control
128 fan speed to keep the temperatures of CPU and the system within specific
129 range. At first a wanted temperature and interval must be set. This is done
130 via thermal_cruise# file. The tolerance# file serves to create T +- tolerance
131 interval. The fan speed will be lowered as long as the current temperature
132 remains below the thermal_cruise# +- tolerance# value. Once the temperature
133 exceeds the high limit (T+tolerance), the fan will be turned on with a
134 specific speed set by pwm# and automatically controlled its PWM duty cycle
135 with the temperature varying. Three conditions may occur:
136
137 (1) If the temperature still exceeds the high limit, PWM duty
138 cycle will increase slowly.
139
140 (2) If the temperature goes below the high limit, but still above the low
141 limit (T-tolerance), the fan speed will be fixed at the current speed because
142 the temperature is in the target range.
143
144 (3) If the temperature goes below the low limit, PWM duty cycle will decrease
145 slowly to 0 or a preset stop value until the temperature exceeds the low
146 limit. (The preset stop value handling is not yet implemented in driver)
147
148 Smart Fan II
149 ------------
150
151 W83792D also provides a special mode for fan. Four temperature points are
152 available. When related temperature sensors detects the temperature in preset
153 temperature region (sf2_point@_fan# +- tolerance#) it will cause fans to run
154 on programmed value from sf2_level@_fan#. You need to set four temperatures
155 for each fan.
156
157
158 /sys files
159 ----------
160
161 pwm[1-3] - this file stores PWM duty cycle or DC value (fan speed) in range:
162 0 (stop) to 255 (full)
163 pwm[1-3]_enable - this file controls mode of fan/temperature control:
164 * 0 Disabled
165 * 1 Manual mode
166 * 2 Smart Fan II
167 * 3 Thermal Cruise
168 pwm[1-3]_mode - Select PWM of DC mode
169 * 0 DC
170 * 1 PWM
171 thermal_cruise[1-3] - Selects the desired temperature for cruise (degC)
172 tolerance[1-3] - Value in degrees of Celsius (degC) for +- T
173 sf2_point[1-4]_fan[1-3] - four temperature points for each fan for Smart Fan II
174 sf2_level[1-3]_fan[1-3] - three PWM/DC levels for each fan for Smart Fan II
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