1 Kernel driver adm1026 1 Kernel driver adm1026
2 ===================== 2 =====================
3 3
4 Supported chips: 4 Supported chips:
5 * Analog Devices ADM1026 5 * Analog Devices ADM1026
6 6
7 Prefix: 'adm1026' 7 Prefix: 'adm1026'
8 8
9 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 9 Addresses scanned: I2C 0x2c, 0x2d, 0x2e
10 10
11 Datasheet: Publicly available at the Analo 11 Datasheet: Publicly available at the Analog Devices website
12 12
13 https://www.onsemi.com/PowerSol 13 https://www.onsemi.com/PowerSolutions/product.do?id=ADM1026
14 14
15 Authors: 15 Authors:
16 - Philip Pokorny <ppokorny@penguincompu 16 - Philip Pokorny <ppokorny@penguincomputing.com> for Penguin Computing
17 - Justin Thiessen <jthiessen@penguincom 17 - Justin Thiessen <jthiessen@penguincomputing.com>
18 18
19 Module Parameters 19 Module Parameters
20 ----------------- 20 -----------------
21 21
22 * gpio_input: int array (min = 1, max = 17) 22 * gpio_input: int array (min = 1, max = 17)
23 List of GPIO pins (0-16) to program as inp 23 List of GPIO pins (0-16) to program as inputs
24 24
25 * gpio_output: int array (min = 1, max = 17) 25 * gpio_output: int array (min = 1, max = 17)
26 List of GPIO pins (0-16) to program as out 26 List of GPIO pins (0-16) to program as outputs
27 27
28 * gpio_inverted: int array (min = 1, max = 17) 28 * gpio_inverted: int array (min = 1, max = 17)
29 List of GPIO pins (0-16) to program as inv 29 List of GPIO pins (0-16) to program as inverted
30 30
31 * gpio_normal: int array (min = 1, max = 17) 31 * gpio_normal: int array (min = 1, max = 17)
32 List of GPIO pins (0-16) to program as nor 32 List of GPIO pins (0-16) to program as normal/non-inverted
33 33
34 * gpio_fan: int array (min = 1, max = 8) 34 * gpio_fan: int array (min = 1, max = 8)
35 List of GPIO pins (0-7) to program as fan 35 List of GPIO pins (0-7) to program as fan tachs
36 36
37 37
38 Description 38 Description
39 ----------- 39 -----------
40 40
41 This driver implements support for the Analog 41 This driver implements support for the Analog Devices ADM1026. Analog
42 Devices calls it a "complete thermal system ma 42 Devices calls it a "complete thermal system management controller."
43 43
44 The ADM1026 implements three (3) temperature s 44 The ADM1026 implements three (3) temperature sensors, 17 voltage sensors,
45 16 general purpose digital I/O lines, eight (8 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 l 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 EE 47 all of the above. There is even 8k bytes of EEPROM memory on chip.
48 48
49 Temperatures are measured in degrees Celsius. 49 Temperatures are measured in degrees Celsius. There are two external
50 sensor inputs and one internal sensor. Each se 50 sensor inputs and one internal sensor. Each sensor has a high and low
51 limit. If the limit is exceeded, an interrupt 51 limit. If the limit is exceeded, an interrupt (#SMBALERT) can be
52 generated. The interrupts can be masked. In ad 52 generated. The interrupts can be masked. In addition, there are over-temp
53 limits for each sensor. If this limit is excee 53 limits for each sensor. If this limit is exceeded, the #THERM output will
54 be asserted. The current temperature and limit 54 be asserted. The current temperature and limits have a resolution of 1
55 degree. 55 degree.
56 56
57 Fan rotation speeds are reported in RPM (rotat 57 Fan rotation speeds are reported in RPM (rotations per minute) but measured
58 in counts of a 22.5kHz internal clock. Each fa 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 lim 59 corresponds to a minimum fan speed. If the limit is exceeded, an interrupt
60 can be generated. Each fan can be programmed t 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 accura 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 slo 62 rounding is done. With a divider of 8, the slowest measurable speed of a
63 two pulse per revolution fan is 661 RPM. 63 two pulse per revolution fan is 661 RPM.
64 64
65 There are 17 voltage sensors. An alarm is trig 65 There are 17 voltage sensors. An alarm is triggered if the voltage has
66 crossed a programmable minimum or maximum limi 66 crossed a programmable minimum or maximum limit. Note that minimum in this
67 case always means 'closest to zero'; this is i 67 case always means 'closest to zero'; this is important for negative voltage
68 measurements. Several inputs have integrated a 68 measurements. Several inputs have integrated attenuators so they can measure
69 higher voltages directly. 3.3V, 5V, 12V, -12V 69 higher voltages directly. 3.3V, 5V, 12V, -12V and battery voltage all have
70 dedicated inputs. There are several inputs sca 70 dedicated inputs. There are several inputs scaled to 0-3V full-scale range
71 for SCSI terminator power. The remaining input 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 ref 72 a 0-2.5V full-scale range. A 2.5V or 1.82V reference voltage is provided
73 for negative voltage measurements. 73 for negative voltage measurements.
74 74
75 If an alarm triggers, it will remain triggered 75 If an alarm triggers, it will remain triggered until the hardware register
76 is read at least once. This means that the cau 76 is read at least once. This means that the cause for the alarm may already
77 have disappeared! Note that in the current imp 77 have disappeared! Note that in the current implementation, all hardware
78 registers are read whenever any data is read ( 78 registers are read whenever any data is read (unless it is less than 2.0
79 seconds since the last update). This means tha 79 seconds since the last update). This means that you can easily miss
80 once-only alarms. 80 once-only alarms.
81 81
82 The ADM1026 measures continuously. Analog inpu 82 The ADM1026 measures continuously. Analog inputs are measured about 4
83 times a second. Fan speed measurement time dep 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 84 divisor. It can take as long as 1.5 seconds to measure all fan speeds.
85 85
86 The ADM1026 has the ability to automatically c 86 The ADM1026 has the ability to automatically control fan speed based on the
87 temperature sensor inputs. Both the PWM output 87 temperature sensor inputs. Both the PWM output and the DAC output can be
88 used to control fan speed. Usually only one of 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 th 89 used. Write the minimum PWM or DAC value to the appropriate control
90 register. Then set the low temperature limit i 90 register. Then set the low temperature limit in the tmin values for each
91 temperature sensor. The range of control is fi 91 temperature sensor. The range of control is fixed at 20 °C, and the
92 largest difference between current and tmin of 92 largest difference between current and tmin of the temperature sensors sets
93 the control output. See the datasheet for seve 93 the control output. See the datasheet for several example circuits for
94 controlling fan speed with the PWM and DAC out 94 controlling fan speed with the PWM and DAC outputs. The fan speed sensors
95 do not have PWM compensation, so it is probabl 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 96 voltage from the power lead rather than on the ground lead.
97 97
98 The datasheet shows an example application wit 98 The datasheet shows an example application with VID signals attached to
99 GPIO lines. Unfortunately, the chip may not be 99 GPIO lines. Unfortunately, the chip may not be connected to the VID lines
100 in this way. The driver assumes that the chips 100 in this way. The driver assumes that the chips *is* connected this way to
101 get a VID voltage. 101 get a VID voltage.
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