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authorJeff Garzik <jgarzik@pretzel.yyz.us>2005-06-26 23:38:58 -0400
committerJeff Garzik <jgarzik@pobox.com>2005-06-26 23:38:58 -0400
commit5696c1944a33b4434a9a1ebb6383b906afd43a10 (patch)
tree16fbe6ba431bcf949ee8645510b0c2fd39b5810f /Documentation/i2c/chips/gl518sm
parent66b04a80eea60cabf9d89fd34deb3234a740052f (diff)
parent020f46a39eb7b99a575b9f4d105fce2b142acdf1 (diff)
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1Kernel driver gl518sm
2=====================
3
4Supported chips:
5 * Genesys Logic GL518SM release 0x00
6 Prefix: 'gl518sm'
7 Addresses scanned: I2C 0x2c and 0x2d
8 Datasheet: http://www.genesyslogic.com/pdf
9 * Genesys Logic GL518SM release 0x80
10 Prefix: 'gl518sm'
11 Addresses scanned: I2C 0x2c and 0x2d
12 Datasheet: http://www.genesyslogic.com/pdf
13
14Authors:
15 Frodo Looijaard <frodol@dds.nl>,
16 Kyösti Mälkki <kmalkki@cc.hut.fi>
17 Hong-Gunn Chew <hglinux@gunnet.org>
18 Jean Delvare <khali@linux-fr.org>
19
20Description
21-----------
22
23IMPORTANT:
24
25For the revision 0x00 chip, the in0, in1, and in2 values (+5V, +3V,
26and +12V) CANNOT be read. This is a limitation of the chip, not the driver.
27
28This driver supports the Genesys Logic GL518SM chip. There are at least
29two revision of this chip, which we call revision 0x00 and 0x80. Revision
300x80 chips support the reading of all voltages and revision 0x00 only
31for VIN3.
32
33The GL518SM implements one temperature sensor, two fan rotation speed
34sensors, and four voltage sensors. It can report alarms through the
35computer speakers.
36
37Temperatures are measured in degrees Celsius. An alarm goes off while the
38temperature is above the over temperature limit, and has not yet dropped
39below the hysteresis limit. The alarm always reflects the current
40situation. Measurements are guaranteed between -10 degrees and +110
41degrees, with a accuracy of +/-3 degrees.
42
43Rotation speeds are reported in RPM (rotations per minute). An alarm is
44triggered if the rotation speed has dropped below a programmable limit. In
45case when you have selected to turn fan1 off, no fan1 alarm is triggered.
46
47Fan readings can be divided by a programmable divider (1, 2, 4 or 8) to
48give the readings more range or accuracy. Not all RPM values can
49accurately be represented, so some rounding is done. With a divider
50of 2, the lowest representable value is around 1900 RPM.
51
52Voltage sensors (also known as VIN sensors) report their values in volts.
53An alarm is triggered if the voltage has crossed a programmable minimum or
54maximum limit. Note that minimum in this case always means 'closest to
55zero'; this is important for negative voltage measurements. The VDD input
56measures voltages between 0.000 and 5.865 volt, with a resolution of 0.023
57volt. The other inputs measure voltages between 0.000 and 4.845 volt, with
58a resolution of 0.019 volt. Note that revision 0x00 chips do not support
59reading the current voltage of any input except for VIN3; limit setting and
60alarms work fine, though.
61
62When an alarm is triggered, you can be warned by a beeping signal through your
63computer speaker. It is possible to enable all beeping globally, or only the
64beeping for some alarms.
65
66If an alarm triggers, it will remain triggered until the hardware register
67is read at least once (except for temperature alarms). This means that the
68cause for the alarm may already have disappeared! Note that in the current
69implementation, all hardware registers are read whenever any data is read
70(unless it is less than 1.5 seconds since the last update). This means that
71you can easily miss once-only alarms.
72
73The GL518SM only updates its values each 1.5 seconds; reading it more often
74will do no harm, but will return 'old' values.