Commit | Line | Data |
---|---|---|
7f15b664 M |
1 | Kernel driver lm87 |
2 | ================== | |
3 | ||
4 | Supported chips: | |
b04f2f7d | 5 | |
7f15b664 | 6 | * National Semiconductor LM87 |
b04f2f7d | 7 | |
7f15b664 | 8 | Prefix: 'lm87' |
b04f2f7d | 9 | |
c7fa3737 | 10 | Addresses scanned: I2C 0x2c - 0x2e |
b04f2f7d | 11 | |
7f15b664 | 12 | Datasheet: http://www.national.com/pf/LM/LM87.html |
b04f2f7d | 13 | |
c7fa3737 | 14 | * Analog Devices ADM1024 |
b04f2f7d | 15 | |
c7fa3737 | 16 | Prefix: 'adm1024' |
b04f2f7d | 17 | |
c7fa3737 | 18 | Addresses scanned: I2C 0x2c - 0x2e |
b04f2f7d | 19 | |
ad736c1a | 20 | Datasheet: https://www.analog.com/en/prod/0,2877,ADM1024,00.html |
7f15b664 | 21 | |
b04f2f7d | 22 | |
7f15b664 | 23 | Authors: |
b04f2f7d MCC |
24 | - Frodo Looijaard <frodol@dds.nl>, |
25 | - Philip Edelbrock <phil@netroedge.com>, | |
26 | - Mark Studebaker <mdsxyz123@yahoo.com>, | |
27 | - Stephen Rousset <stephen.rousset@rocketlogix.com>, | |
28 | - Dan Eaton <dan.eaton@rocketlogix.com>, | |
29 | - Jean Delvare <jdelvare@suse.de>, | |
30 | - Original 2.6 port Jeff Oliver | |
7f15b664 M |
31 | |
32 | Description | |
33 | ----------- | |
34 | ||
c7fa3737 JD |
35 | This driver implements support for the National Semiconductor LM87 |
36 | and the Analog Devices ADM1024. | |
7f15b664 M |
37 | |
38 | The LM87 implements up to three temperature sensors, up to two fan | |
39 | rotation speed sensors, up to seven voltage sensors, alarms, and some | |
c7fa3737 | 40 | miscellaneous stuff. The ADM1024 is fully compatible. |
7f15b664 M |
41 | |
42 | Temperatures are measured in degrees Celsius. Each input has a high | |
43 | and low alarm settings. A high limit produces an alarm when the value | |
44 | goes above it, and an alarm is also produced when the value goes below | |
45 | the low limit. | |
46 | ||
47 | Fan rotation speeds are reported in RPM (rotations per minute). An alarm is | |
48 | triggered if the rotation speed has dropped below a programmable limit. Fan | |
49 | readings can be divided by a programmable divider (1, 2, 4 or 8) to give | |
50 | the readings more range or accuracy. Not all RPM values can accurately be | |
51 | represented, so some rounding is done. With a divider of 2, the lowest | |
52 | representable value is around 2600 RPM. | |
53 | ||
54 | Voltage sensors (also known as IN sensors) report their values in | |
55 | volts. An alarm is triggered if the voltage has crossed a programmable | |
56 | minimum or maximum limit. Note that minimum in this case always means | |
57 | 'closest to zero'; this is important for negative voltage measurements. | |
58 | ||
59 | If an alarm triggers, it will remain triggered until the hardware register | |
60 | is read at least once. This means that the cause for the alarm may | |
61 | already have disappeared! Note that in the current implementation, all | |
62 | hardware registers are read whenever any data is read (unless it is less | |
63 | than 1.0 seconds since the last update). This means that you can easily | |
64 | miss once-only alarms. | |
65 | ||
66 | The lm87 driver only updates its values each 1.0 seconds; reading it more | |
67 | often will do no harm, but will return 'old' values. | |
68 | ||
69 | ||
70 | Hardware Configurations | |
71 | ----------------------- | |
72 | ||
73 | The LM87 has four pins which can serve one of two possible functions, | |
74 | depending on the hardware configuration. | |
75 | ||
76 | Some functions share pins, so not all functions are available at the same | |
47064d64 BH |
77 | time. Which are depends on the hardware setup. This driver normally |
78 | assumes that firmware configured the chip correctly. Where this is not | |
79 | the case, platform code must set the I2C client's platform_data to point | |
80 | to a u8 value to be written to the channel register. | |
7f15b664 M |
81 | |
82 | For reference, here is the list of exclusive functions: | |
83 | - in0+in5 (default) or temp3 | |
84 | - fan1 (default) or in6 | |
85 | - fan2 (default) or in7 | |
86 | - VID lines (default) or IRQ lines (not handled by this driver) |