root/lm-sensors/trunk/doc/chips/pc87360 @ 2508

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1Kernel driver `pc87360.o'
2=========================
3
4Status: Beta, somewhat tested.
5
6Supported chips:
7  * National Semiconductor PC87360, PC87363, PC87364, PC87365 and PC87366
8    Addresses scanned: none, address read from Super I/O config space
9    Datasheets:
10        http://www.national.com/pf/PC/PC87360.html
11        http://www.national.com/pf/PC/PC87363.html
12        http://www.national.com/pf/PC/PC87364.html
13        http://www.national.com/pf/PC/PC87365.html
14        http://www.national.com/pf/PC/PC87366.html
15
16Authors: Jean Delvare <khali@linux-fr.org>
17
18Thanks to Sandeep Mehta, Tonko de Rooy and Daniel Ceregatti for testing.
19
20
21Module Parameters
22-----------------
23
24init (int):
25  Chip initialization level:
26   0: None
27  *1: Forcibly enable internal voltage and temperature channels, except in9
28   2: Forcibly enable all voltage and temperature channels, except in9
29   3: Forcibly enable all voltage and temperature channels, including in9
30
31
32Description
33-----------
34
35The National Semiconductor PC87360 Super I/O chip contains monitoring and
36PWM control circuitry for two fans. The PC87363 chip is similar, and the
37PC87364 chip has monitoring and PWM control for a third fan.
38
39The National Semiconductor PC87365 and PC87366 Super I/O chips are complete
40hardware monitoring chipsets, not only controling and monitoring three fans,
41but also monitoring eleven voltage inputs and two (PC87365) or six
42(PC87366) remote temperatures.
43
44
45Fan Monitoring
46--------------
47
48Fan rotation speeds are reported in RPM (revolutions per minute). An alarm
49is triggered if the rotation speed has dropped below a programmable limit.
50A different alarm is triggered if the fan speed is too low to be measured.
51It is suggested to increase the fan divider (which is really a clock
52divider) in this case.
53
54Fan readings are affected by a programmable clock divider (1, 2, 4 or 8).
55By changing the divider, you give the readings more range or accuracy.
56
57                slowest         accuracy        highest
58                measurable      around 3000     accurate
59    divider     speed (RPM)     RPM (RPM)       speed (RPM)
60         1        1882              18           6928
61         2         941              37           4898
62         4         470              74           3464
63         8         235             150           2449
64
65For the curious, here is how the values above were computed:
66 * slowest measurable speed: clock/(255*divider)
67 * accuracy around 3000 RPM: 3000^2/clock
68 * highest accurate speed: sqrt(clock*100)
69The clock speed for the PC87360 family is 480 kHz. I arbitrarily chose 100
70RPM as the lowest acceptable accuracy.
71
72Note that not all RPM values can be represented. This is not only true for
73the measured speeds, but also for the programmable low limits, so don't be
74surprised if you try to set, say, fan1_min to 2900 and it finaly reads
752909. Likewise, if you try to set fan1_min to 0, it'll be set to the
76lowest representable RPM value (depending on the divider).
77
78
79Fan Control
80-----------
81
82PWM (pulse width modulation) values range from 0 to 255, with 0 meaning
83that the fan is stopped, and 255 meaning that the fan goes at full speed.
84
85Be extremely careful when changing PWM values. Low PWM values, even
86non-zero, can stop the fan, which may cause irreversible damage to your
87hardware if temperature increases too much. When changing PWM values, go
88step by step and keep an eye on temperatures.
89
90One user reported problems with PWM. Changing PWM values would break fan
91speed readings. No explanation nor fix could be found.
92
93
94Temperature Monitoring
95----------------------
96
97Temperatures are reported in degrees Celcius. Each temperature measured has
98associated low, high and overtemperature limits, each of which triggers an
99alarm when crossed.
100
101The first two temperature channels are external. The third one (PC87366
102only) is internal.
103
104The PC87366 has three additional temperature channels, based on
105thermistors (as opposed to thermal diodes for the first temperature
106channels). For technical reasons, these channels are held by the VLM
107(voltage level monitor) logical device, not the TMS (temperature
108measurement) one. The formula to convert the measured voltage into a
109temperature isn't known, so the driver doesn't handle these temperature
110channels at all yet.
111
112
113Voltage Monitoring
114------------------
115
116Voltages are reported relatively to a reference voltage, either internal or
117external. Some of them (in7:Vsb, in8:Vdd and in10:AVdd) are divided by two
118internally, you will have to compensate in sensors.conf. Others (in0 to in6)
119are likely to be divided externally. The meaning of each of these inputs as
120well as the values of the resistors used for division is left to the
121motherboard manufacturers, so you will have to document yourself and edit
122sensors.conf accordingly. National Semiconductor has a document with
123recommended resistor values for some voltages, but this still leaves much
124room for per motherboard specificities, unfortunately.
125
126Each voltage measured has associated low and high limit, each of which
127triggers an alarm when crossed.
128
129
130General Remarks
131---------------
132
133If an alarm triggers, it will remain triggered until the hardware register
134is read at least once. This means that the cause for the alarm may already
135have disappeared! Note that all hardware registers are read whenever any
136data is read (unless it is less than 2 seconds since the last update, in
137which case cached values are returned instead). As a consequence, when
138a once-only alarm triggers, it may take 2 seconds for it to show, and 2
139more seconds for it to disappear.
140
141Monitoring of in9 isn't enabled at lower init levels (<3) because that
142channel measures the battery voltage (Vbat). It is a known fact that
143repeatedly sampling the battery voltage reduces its lifetime. National
144Semiconductor smartly designed their chipset so that in9 is sampled only
145once every 1024 sampling cycles (that is every 34 minutes at the default
146sampling rate), so the effect is attenuated, but still present.
147
148
149Limitations
150-----------
151
152There are a few unimplemented configuration options at the moment. We'll
153add them if someone needs them.
154
155The datasheets suggests that some values (fan mins, fan dividers)
156shouldn't be changed once the monitoring has started, but we ignore that
157recommendation. We'll reconsider if it actually causes trouble.
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