]>
Commit | Line | Data |
---|---|---|
7f15b664 M |
1 | Kernel driver adm1026 |
2 | ===================== | |
3 | ||
4 | Supported chips: | |
5 | * Analog Devices ADM1026 | |
b04f2f7d | 6 | |
7f15b664 | 7 | Prefix: 'adm1026' |
b04f2f7d | 8 | |
7f15b664 | 9 | Addresses scanned: I2C 0x2c, 0x2d, 0x2e |
b04f2f7d | 10 | |
7f15b664 | 11 | Datasheet: Publicly available at the Analog Devices website |
b04f2f7d | 12 | |
ad736c1a | 13 | https://www.onsemi.com/PowerSolutions/product.do?id=ADM1026 |
7f15b664 M |
14 | |
15 | Authors: | |
b04f2f7d MCC |
16 | - Philip Pokorny <ppokorny@penguincomputing.com> for Penguin Computing |
17 | - Justin Thiessen <jthiessen@penguincomputing.com> | |
7f15b664 M |
18 | |
19 | Module Parameters | |
20 | ----------------- | |
21 | ||
22 | * gpio_input: int array (min = 1, max = 17) | |
b04f2f7d MCC |
23 | List of GPIO pins (0-16) to program as inputs |
24 | ||
7f15b664 | 25 | * gpio_output: int array (min = 1, max = 17) |
b04f2f7d MCC |
26 | List of GPIO pins (0-16) to program as outputs |
27 | ||
7f15b664 | 28 | * gpio_inverted: int array (min = 1, max = 17) |
b04f2f7d MCC |
29 | List of GPIO pins (0-16) to program as inverted |
30 | ||
7f15b664 | 31 | * gpio_normal: int array (min = 1, max = 17) |
b04f2f7d MCC |
32 | List of GPIO pins (0-16) to program as normal/non-inverted |
33 | ||
7f15b664 | 34 | * gpio_fan: int array (min = 1, max = 8) |
b04f2f7d | 35 | List of GPIO pins (0-7) to program as fan tachs |
7f15b664 M |
36 | |
37 | ||
38 | Description | |
39 | ----------- | |
40 | ||
41 | This driver implements support for the Analog Devices ADM1026. Analog | |
42 | Devices calls it a "complete thermal system management controller." | |
43 | ||
44 | The ADM1026 implements three (3) temperature sensors, 17 voltage sensors, | |
45 | 16 general purpose digital I/O lines, eight (8) fan speed sensors (8-bit), | |
46 | an analog output and a PWM output along with limit, alarm and mask bits for | |
47 | all of the above. There is even 8k bytes of EEPROM memory on chip. | |
48 | ||
49 | Temperatures are measured in degrees Celsius. There are two external | |
50 | sensor inputs and one internal sensor. Each sensor has a high and low | |
51 | limit. If the limit is exceeded, an interrupt (#SMBALERT) can be | |
52 | generated. The interrupts can be masked. In addition, there are over-temp | |
53 | limits for each sensor. If this limit is exceeded, the #THERM output will | |
54 | be asserted. The current temperature and limits have a resolution of 1 | |
55 | degree. | |
56 | ||
57 | Fan rotation speeds are reported in RPM (rotations per minute) but measured | |
58 | in counts of a 22.5kHz internal clock. Each fan has a high limit which | |
59 | corresponds to a minimum fan speed. If the limit is exceeded, an interrupt | |
60 | can be generated. Each fan can be programmed to divide the reference clock | |
61 | by 1, 2, 4 or 8. Not all RPM values can accurately be represented, so some | |
62 | rounding is done. With a divider of 8, the slowest measurable speed of a | |
63 | two pulse per revolution fan is 661 RPM. | |
64 | ||
65 | There are 17 voltage sensors. An alarm is triggered if the voltage has | |
66 | crossed a programmable minimum or maximum limit. Note that minimum in this | |
67 | case always means 'closest to zero'; this is important for negative voltage | |
68 | measurements. Several inputs have integrated attenuators so they can measure | |
69 | higher voltages directly. 3.3V, 5V, 12V, -12V and battery voltage all have | |
70 | dedicated inputs. There are several inputs scaled to 0-3V full-scale range | |
71 | for SCSI terminator power. The remaining inputs are not scaled and have | |
72 | a 0-2.5V full-scale range. A 2.5V or 1.82V reference voltage is provided | |
73 | for negative voltage measurements. | |
74 | ||
75 | If an alarm triggers, it will remain triggered until the hardware register | |
76 | is read at least once. This means that the cause for the alarm may already | |
77 | have disappeared! Note that in the current implementation, all hardware | |
78 | registers are read whenever any data is read (unless it is less than 2.0 | |
79 | seconds since the last update). This means that you can easily miss | |
80 | once-only alarms. | |
81 | ||
82 | The ADM1026 measures continuously. Analog inputs are measured about 4 | |
83 | times a second. Fan speed measurement time depends on fan speed and | |
84 | divisor. It can take as long as 1.5 seconds to measure all fan speeds. | |
85 | ||
86 | The ADM1026 has the ability to automatically control fan speed based on the | |
87 | temperature sensor inputs. Both the PWM output and the DAC output can be | |
88 | used to control fan speed. Usually only one of these two outputs will be | |
89 | used. Write the minimum PWM or DAC value to the appropriate control | |
90 | register. Then set the low temperature limit in the tmin values for each | |
be2a608b | 91 | temperature sensor. The range of control is fixed at 20 °C, and the |
7f15b664 M |
92 | largest difference between current and tmin of the temperature sensors sets |
93 | the control output. See the datasheet for several example circuits for | |
94 | controlling fan speed with the PWM and DAC outputs. The fan speed sensors | |
95 | do not have PWM compensation, so it is probably best to control the fan | |
96 | voltage from the power lead rather than on the ground lead. | |
97 | ||
98 | The datasheet shows an example application with VID signals attached to | |
99 | GPIO lines. Unfortunately, the chip may not be connected to the VID lines | |
100 | in this way. The driver assumes that the chips *is* connected this way to | |
101 | get a VID voltage. |