Commit | Line | Data |
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7f15b664 RM |
1 | Kernel driver adm1026 |
2 | ===================== | |
3 | ||
4 | Supported chips: | |
5 | * Analog Devices ADM1026 | |
6 | Prefix: 'adm1026' | |
7 | Addresses scanned: I2C 0x2c, 0x2d, 0x2e | |
8 | Datasheet: Publicly available at the Analog Devices website | |
9 | http://www.analog.com/en/prod/0,,766_825_ADM1026,00.html | |
10 | ||
11 | Authors: | |
12 | Philip Pokorny <ppokorny@penguincomputing.com> for Penguin Computing | |
13 | Justin Thiessen <jthiessen@penguincomputing.com> | |
14 | ||
15 | Module Parameters | |
16 | ----------------- | |
17 | ||
18 | * gpio_input: int array (min = 1, max = 17) | |
19 | List of GPIO pins (0-16) to program as inputs | |
20 | * gpio_output: int array (min = 1, max = 17) | |
21 | List of GPIO pins (0-16) to program as outputs | |
22 | * gpio_inverted: int array (min = 1, max = 17) | |
23 | List of GPIO pins (0-16) to program as inverted | |
24 | * gpio_normal: int array (min = 1, max = 17) | |
25 | List of GPIO pins (0-16) to program as normal/non-inverted | |
26 | * gpio_fan: int array (min = 1, max = 8) | |
27 | List of GPIO pins (0-7) to program as fan tachs | |
28 | ||
29 | ||
30 | Description | |
31 | ----------- | |
32 | ||
33 | This driver implements support for the Analog Devices ADM1026. Analog | |
34 | Devices calls it a "complete thermal system management controller." | |
35 | ||
36 | The ADM1026 implements three (3) temperature sensors, 17 voltage sensors, | |
37 | 16 general purpose digital I/O lines, eight (8) fan speed sensors (8-bit), | |
38 | an analog output and a PWM output along with limit, alarm and mask bits for | |
39 | all of the above. There is even 8k bytes of EEPROM memory on chip. | |
40 | ||
41 | Temperatures are measured in degrees Celsius. There are two external | |
42 | sensor inputs and one internal sensor. Each sensor has a high and low | |
43 | limit. If the limit is exceeded, an interrupt (#SMBALERT) can be | |
44 | generated. The interrupts can be masked. In addition, there are over-temp | |
45 | limits for each sensor. If this limit is exceeded, the #THERM output will | |
46 | be asserted. The current temperature and limits have a resolution of 1 | |
47 | degree. | |
48 | ||
49 | Fan rotation speeds are reported in RPM (rotations per minute) but measured | |
50 | in counts of a 22.5kHz internal clock. Each fan has a high limit which | |
51 | corresponds to a minimum fan speed. If the limit is exceeded, an interrupt | |
52 | can be generated. Each fan can be programmed to divide the reference clock | |
53 | by 1, 2, 4 or 8. Not all RPM values can accurately be represented, so some | |
54 | rounding is done. With a divider of 8, the slowest measurable speed of a | |
55 | two pulse per revolution fan is 661 RPM. | |
56 | ||
57 | There are 17 voltage sensors. An alarm is triggered if the voltage has | |
58 | crossed a programmable minimum or maximum limit. Note that minimum in this | |
59 | case always means 'closest to zero'; this is important for negative voltage | |
60 | measurements. Several inputs have integrated attenuators so they can measure | |
61 | higher voltages directly. 3.3V, 5V, 12V, -12V and battery voltage all have | |
62 | dedicated inputs. There are several inputs scaled to 0-3V full-scale range | |
63 | for SCSI terminator power. The remaining inputs are not scaled and have | |
64 | a 0-2.5V full-scale range. A 2.5V or 1.82V reference voltage is provided | |
65 | for negative voltage measurements. | |
66 | ||
67 | If an alarm triggers, it will remain triggered until the hardware register | |
68 | is read at least once. This means that the cause for the alarm may already | |
69 | have disappeared! Note that in the current implementation, all hardware | |
70 | registers are read whenever any data is read (unless it is less than 2.0 | |
71 | seconds since the last update). This means that you can easily miss | |
72 | once-only alarms. | |
73 | ||
74 | The ADM1026 measures continuously. Analog inputs are measured about 4 | |
75 | times a second. Fan speed measurement time depends on fan speed and | |
76 | divisor. It can take as long as 1.5 seconds to measure all fan speeds. | |
77 | ||
78 | The ADM1026 has the ability to automatically control fan speed based on the | |
79 | temperature sensor inputs. Both the PWM output and the DAC output can be | |
80 | used to control fan speed. Usually only one of these two outputs will be | |
81 | used. Write the minimum PWM or DAC value to the appropriate control | |
82 | register. Then set the low temperature limit in the tmin values for each | |
83 |