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1 | Kernel driver adc128d818 | ||
2 | ======================== | ||
3 | |||
4 | Supported chips: | ||
5 | * Texas Instruments ADC818D818 | ||
6 | Prefix: 'adc818d818' | ||
7 | Addresses scanned: I2C 0x1d, 0x1e, 0x1f, 0x2d, 0x2e, 0x2f | ||
8 | Datasheet: Publicly available at the TI website | ||
9 | http://www.ti.com/ | ||
10 | |||
11 | Author: Guenter Roeck | ||
12 | |||
13 | Description | ||
14 | ----------- | ||
15 | |||
16 | This driver implements support for the Texas Instruments ADC128D818. | ||
17 | It is described as 'ADC System Monitor with Temperature Sensor'. | ||
18 | |||
19 | The ADC128D818 implements one temperature sensor and seven voltage sensors. | ||
20 | |||
21 | Temperatures are measured in degrees Celsius. There is one set of limits. | ||
22 | When the HOT Temperature Limit is crossed, this will cause an alarm that will | ||
23 | be reasserted until the temperature drops below the HOT Hysteresis. | ||
24 | Measurements are guaranteed between -55 and +125 degrees. The temperature | ||
25 | measurement has a resolution of 0.5 degrees; the limits have a resolution | ||
26 | of 1 degree. | ||
27 | |||
28 | Voltage sensors (also known as IN sensors) report their values in volts. | ||
29 | An alarm is triggered if the voltage has crossed a programmable minimum | ||
30 | or maximum limit. Note that minimum in this case always means 'closest to | ||
31 | zero'; this is important for negative voltage measurements. All voltage | ||
32 | inputs can measure voltages between 0 and 2.55 volts, with a resolution | ||
33 | of 0.625 mV. | ||
34 | |||
35 | If an alarm triggers, it will remain triggered until the hardware register | ||
36 | is read at least once. This means that the cause for the alarm may | ||
37 | already have disappeared by the time the alarm is read. The driver | ||
38 | caches the alarm status for each sensor until it is at least reported | ||
39 | once, to ensure that alarms are reported to user space. | ||
40 | |||
41 | The ADC128D818 only updates its values approximately once per second; | ||
42 | reading it more often will do no harm, but will return 'old' values. | ||
43 | |||
44 | In addition to the scanned address list, the chip can also be configured for | ||
45 | addresses 0x35 to 0x37. Those addresses are not scanned. You have to instantiate | ||
46 | the driver explicitly if the chip is configured for any of those addresses in | ||
47 | your system. | ||