projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 57d60b1b GR |
1 | Kernel driver emc1403 |
| 2 | ===================== | |
| 3 | ||
| 4 | Supported chips: | |
| 5 | * SMSC / Microchip EMC1402, EMC1412 | |
| 6 | Addresses scanned: I2C 0x18, 0x1c, 0x29, 0x4c, 0x4d, 0x5c | |
| 7 | Prefix: 'emc1402' | |
| 8 | Datasheets: | |
| 9 | http://ww1.microchip.com/downloads/en/DeviceDoc/1412.pdf | |
| 10 | http://ww1.microchip.com/downloads/en/DeviceDoc/1402.pdf | |
| 11 | * SMSC / Microchip EMC1403, EMC1404, EMC1413, EMC1414 | |
| 12 | Addresses scanned: I2C 0x18, 0x29, 0x4c, 0x4d | |
| 13 | Prefix: 'emc1403', 'emc1404' | |
| 14 | Datasheets: | |
| 15 | http://ww1.microchip.com/downloads/en/DeviceDoc/1403_1404.pdf | |
| 16 | http://ww1.microchip.com/downloads/en/DeviceDoc/1413_1414.pdf | |
| 17 | * SMSC / Microchip EMC1422 | |
| 18 | Addresses scanned: I2C 0x4c | |
| 19 | Prefix: 'emc1422' | |
| 20 | Datasheet: | |
| 21 | http://ww1.microchip.com/downloads/en/DeviceDoc/1422.pdf | |
| 22 | * SMSC / Microchip EMC1423, EMC1424 | |
| 23 | Addresses scanned: I2C 0x4c | |
| 24 | Prefix: 'emc1423', 'emc1424' | |
| 25 | Datasheet: | |
| 26 | http://ww1.microchip.com/downloads/en/DeviceDoc/1423_1424.pdf | |
| 27 | ||
| 28 | Author: | |
| 29 | Kalhan Trisal <kalhan.trisal@intel.com | |
| 30 | ||
| 31 | ||
| 32 | Description | |
| 33 | ----------- | |
| 34 | ||
| 35 | The Standard Microsystems Corporation (SMSC) / Microchip EMC14xx chips | |
| 36 | contain up to four temperature sensors. EMC14x2 support two sensors | |
| 37 | (one internal, one external). EMC14x3 support three sensors (one internal, | |
| 38 | two external), and EMC14x4 support four sensors (one internal, three | |
| 39 | external). | |
| 40 | ||
| 41 | The chips implement three limits for each sensor: low (tempX_min), high | |
| 42 | (tempX_max) and critical (tempX_crit.) The chips also implement an | |
| 43 | hysteresis mechanism which applies to all limits. The relative difference | |
| 44 | is stored in a single register on the chip, which means that the relative | |
| 45 | difference between the limit and its hysteresis is always the same for | |
| 46 | all three limits. | |
| 47 | ||
| 48 | This implementation detail implies the following: | |
| 49 | * When setting a limit, its hysteresis will automatically follow, the | |
| 50 | difference staying unchanged. For example, if the old critical limit | |
| 51 | was 80 degrees C, and the hysteresis was 75 degrees C, and you change | |
| 52 | the critical limit to 90 degrees C, then the hysteresis will | |
| 53 | automatically change to 85 degrees C. | |
| 84899d39 GR |
54 | * The hysteresis values can't be set independently. We decided to make |
| 55 | only temp1_crit_hyst writable, while all other hysteresis attributes | |
| 56 | are read-only. Setting temp1_crit_hyst writes the difference between | |
| 57 | temp1_crit_hyst and temp1_crit into the chip, and the same relative | |
| 58 | hysteresis applies automatically to all other limits. | |
| 57d60b1b | 59 | * The limits should be set before the hysteresis. |