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authorR.Marek@sh.cvut.cz <R.Marek@sh.cvut.cz>2005-05-26 08:42:19 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2005-06-22 00:52:02 -0400
commit7f15b66468b7003d5241e352a007e73be5519b20 (patch)
treec9333e14baae06a831c8515d9e1e24808826053e /Documentation/i2c/chips/pc87360
parent2bf34a1ca9d570dd4fab4d95c4de82d873ecf718 (diff)
[PATCH] I2C: documentation update 2/3
This patch adds missing documentation for system health monitoring chips. I would like to thank all people, who helped me with this project. Signed-off-by: Rudolf Marek <r.marek@sh.cvut.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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1Kernel driver pc87360
2=====================
3
4Supported chips:
5 * National Semiconductor PC87360, PC87363, PC87364, PC87365 and PC87366
6 Prefixes: 'pc87360', 'pc87363', 'pc87364', 'pc87365', 'pc87366'
7 Addresses scanned: none, address read from Super I/O config space
8 Datasheets:
9 http://www.national.com/pf/PC/PC87360.html
10 http://www.national.com/pf/PC/PC87363.html
11 http://www.national.com/pf/PC/PC87364.html
12 http://www.national.com/pf/PC/PC87365.html
13 http://www.national.com/pf/PC/PC87366.html
14
15Authors: Jean Delvare <khali@linux-fr.org>
16
17Thanks to Sandeep Mehta, Tonko de Rooy and Daniel Ceregatti for testing.
18Thanks to Rudolf Marek for helping me investigate conversion issues.
19
20
21Module Parameters
22-----------------
23
24* init 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
31Note that this parameter has no effect for the PC87360, PC87363 and PC87364
32chips.
33
34Also note that for the PC87366, initialization levels 2 and 3 don't enable
35all temperature channels, because some of them share pins with each other,
36so they can't be used at the same time.
37
38
39Description
40-----------
41
42The National Semiconductor PC87360 Super I/O chip contains monitoring and
43PWM control circuitry for two fans. The PC87363 chip is similar, and the
44PC87364 chip has monitoring and PWM control for a third fan.
45
46The National Semiconductor PC87365 and PC87366 Super I/O chips are complete
47hardware monitoring chipsets, not only controlling and monitoring three fans,
48but also monitoring eleven voltage inputs and two (PC87365) or up to four
49(PC87366) temperatures.
50
51 Chip #vin #fan #pwm #temp devid
52
53 PC87360 - 2 2 - 0xE1
54 PC87363 - 2 2 - 0xE8
55 PC87364 - 3 3 - 0xE4
56 PC87365 11 3 3 2 0xE5
57 PC87366 11 3 3 3-4 0xE9
58
59The driver assumes that no more than one chip is present, and one of the
60standard Super I/O addresses is used (0x2E/0x2F or 0x4E/0x4F)
61
62Fan Monitoring
63--------------
64
65Fan rotation speeds are reported in RPM (revolutions per minute). An alarm
66is triggered if the rotation speed has dropped below a programmable limit.
67A different alarm is triggered if the fan speed is too low to be measured.
68
69Fan readings are affected by a programmable clock divider, giving the
70readings more range or accuracy. Usually, users have to learn how it works,
71but this driver implements dynamic clock divider selection, so you don't
72have to care no more.
73
74For reference, here are a few values about clock dividers:
75
76 slowest accuracy highest
77 measurable around 3000 accurate
78 divider speed (RPM) RPM (RPM) speed (RPM)
79 1 1882 18 6928
80 2 941 37 4898
81 4 470 74 3464
82 8 235 150 2449
83
84For the curious, here is how the values above were computed:
85 * slowest measurable speed: clock/(255*divider)
86 * accuracy around 3000 RPM: 3000^2/clock
87 * highest accurate speed: sqrt(clock*100)
88The clock speed for the PC87360 family is 480 kHz. I arbitrarily chose 100
89RPM as the lowest acceptable accuracy.
90
91As mentioned above, you don't have to care about this no more.
92
93Note that not all RPM values can be represented, even when the best clock
94divider is selected. This is not only true for the measured speeds, but
95also for the programmable low limits, so don't be surprised if you try to
96set, say, fan1_min to 2900 and it finally reads 2909.
97
98
99Fan Control
100-----------
101
102PWM (pulse width modulation) values range from 0 to 255, with 0 meaning
103that the fan is stopped, and 255 meaning that the fan goes at full speed.
104
105Be extremely careful when changing PWM values. Low PWM values, even
106non-zero, can stop the fan, which may cause irreversible damage to your
107hardware if temperature increases too much. When changing PWM values, go
108step by step and keep an eye on temperatures.
109
110One user reported problems with PWM. Changing PWM values would break fan
111speed readings. No explanation nor fix could be found.
112
113
114Temperature Monitoring
115----------------------
116
117Temperatures are reported in degrees Celsius. Each temperature measured has
118associated low, high and overtemperature limits, each of which triggers an
119alarm when crossed.
120
121The first two temperature channels are external. The third one (PC87366
122only) is internal.
123
124The PC87366 has three additional temperature channels, based on
125thermistors (as opposed to thermal diodes for the first three temperature
126channels). For technical reasons, these channels are held by the VLM
127(voltage level monitor) logical device, not the TMS (temperature
128measurement) one. As a consequence, these temperatures are exported as
129voltages, and converted into temperatures in user-space.
130
131Note that these three additional channels share their pins with the
132external thermal diode channels, so you (physically) can't use them all at
133the same time. Although it should be possible to mix the two sensor types,
134the documents from National Semiconductor suggest that motherboard
135manufacturers should choose one type and stick to it. So you will more
136likely have either channels 1 to 3 (thermal diodes) or 3 to 6 (internal
137thermal diode, and thermistors).
138
139
140Voltage Monitoring
141------------------
142
143Voltages are reported relatively to a reference voltage, either internal or
144external. Some of them (in7:Vsb, in8:Vdd and in10:AVdd) are divided by two
145internally, you will have to compensate in sensors.conf. Others (in0 to in6)
146are likely to be divided externally. The meaning of each of these inputs as
147well as the values of the resistors used for division is left to the
148motherboard manufacturers, so you will have to document yourself and edit
149sensors.conf accordingly. National Semiconductor has a document with
150recommended resistor values for some voltages, but this still leaves much
151room for per motherboard specificities, unfortunately. Even worse,
152motherboard manufacturers don't seem to care about National Semiconductor's
153recommendations.
154
155Each voltage measured has associated low and high limits, each of which
156triggers an alarm when crossed.
157
158When available, VID inputs are used to provide the nominal CPU Core voltage.
159The driver will default to VRM 9.0, but this can be changed from user-space.
160The chipsets can handle two sets of VID inputs (on dual-CPU systems), but
161the driver will only export one for now. This may change later if there is
162a need.
163
164
165General Remarks
166---------------
167
168If an alarm triggers, it will remain triggered until the hardware register
169is read at least once. This means that the cause for the alarm may already
170have disappeared! Note that all hardware registers are read whenever any
171data is read (unless it is less than 2 seconds since the last update, in
172which case cached values are returned instead). As a consequence, when
173a once-only alarm triggers, it may take 2 seconds for it to show, and 2
174more seconds for it to disappear.
175
176Monitoring of in9 isn't enabled at lower init levels (<3) because that
177channel measures the battery voltage (Vbat). It is a known fact that
178repeatedly sampling the battery voltage reduces its lifetime. National
179Semiconductor smartly designed their chipset so that in9 is sampled only
180once every 1024 sampling cycles (that is every 34 minutes at the default
181sampling rate), so the effect is attenuated, but still present.
182
183
184Limitations
185-----------
186
187The datasheets suggests that some values (fan mins, fan dividers)
188shouldn't be changed once the monitoring has started, but we ignore that
189recommendation. We'll reconsider if it actually causes trouble.