projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| b4c9c1a7 GR |
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. |