projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 7f15b664 M |
1 | Kernel driver lm90 |
| 2 | ================== | |
| 3 | ||
| 4 | Supported chips: | |
| 5 | * National Semiconductor LM90 | |
| 6 | Prefix: 'lm90' | |
| 7 | Addresses scanned: I2C 0x4c | |
| 8 | Datasheet: Publicly available at the National Semiconductor website | |
| 9 | http://www.national.com/pf/LM/LM90.html | |
| 10 | * National Semiconductor LM89 | |
| 11 | Prefix: 'lm99' | |
| 12 | Addresses scanned: I2C 0x4c and 0x4d | |
| 13 | Datasheet: Publicly available at the National Semiconductor website | |
| 14 | http://www.national.com/pf/LM/LM89.html | |
| 15 | * National Semiconductor LM99 | |
| 16 | Prefix: 'lm99' | |
| 17 | Addresses scanned: I2C 0x4c and 0x4d | |
| 18 | Datasheet: Publicly available at the National Semiconductor website | |
| 19 | http://www.national.com/pf/LM/LM99.html | |
| 20 | * National Semiconductor LM86 | |
| 21 | Prefix: 'lm86' | |
| 22 | Addresses scanned: I2C 0x4c | |
| 23 | Datasheet: Publicly available at the National Semiconductor website | |
| 24 | http://www.national.com/pf/LM/LM86.html | |
| 25 | * Analog Devices ADM1032 | |
| 26 | Prefix: 'adm1032' | |
| 27 | Addresses scanned: I2C 0x4c | |
| 28 | Datasheet: Publicly available at the Analog Devices website | |
| 29 | http://products.analog.com/products/info.asp?product=ADM1032 | |
| 30 | * Analog Devices ADT7461 | |
| 31 | Prefix: 'adt7461' | |
| 32 | Addresses scanned: I2C 0x4c | |
| 33 | Datasheet: Publicly available at the Analog Devices website | |
| 34 | http://products.analog.com/products/info.asp?product=ADT7461 | |
| 35 | Note: Only if in ADM1032 compatibility mode | |
| 36 | * Maxim MAX6657 | |
| 37 | Prefix: 'max6657' | |
| 38 | Addresses scanned: I2C 0x4c | |
| 39 | Datasheet: Publicly available at the Maxim website | |
| 40 | http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 | |
| 41 | * Maxim MAX6658 | |
| 42 | Prefix: 'max6657' | |
| 43 | Addresses scanned: I2C 0x4c | |
| 44 | Datasheet: Publicly available at the Maxim website | |
| 45 | http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 | |
| 46 | * Maxim MAX6659 | |
| 47 | Prefix: 'max6657' | |
| 48 | Addresses scanned: I2C 0x4c, 0x4d (unsupported 0x4e) | |
| 49 | Datasheet: Publicly available at the Maxim website | |
| 50 | http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 | |
| 51 | ||
| 52 | ||
| 53 | Author: Jean Delvare <khali@linux-fr.org> | |
| 54 | ||
| 55 | ||
| 56 | Description | |
| 57 | ----------- | |
| 58 | ||
| 59 | The LM90 is a digital temperature sensor. It senses its own temperature as | |
| 60 | well as the temperature of up to one external diode. It is compatible | |
| 61 | with many other devices such as the LM86, the LM89, the LM99, the ADM1032, | |
| 62 | the MAX6657, MAX6658 and the MAX6659 all of which are supported by this driver. | |
| 63 | Note that there is no easy way to differentiate between the last three | |
| 64 | variants. The extra address and features of the MAX6659 are not supported by | |
| 65 | this driver. Additionally, the ADT7461 is supported if found in ADM1032 | |
| 66 | compatibility mode. | |
| 67 | ||
| 68 | The specificity of this family of chipsets over the ADM1021/LM84 | |
| 69 | family is that it features critical limits with hysteresis, and an | |
| 70 | increased resolution of the remote temperature measurement. | |
| 71 | ||
| 72 | The different chipsets of the family are not strictly identical, although | |
| 73 | very similar. This driver doesn't handle any specific feature for now, | |
| 74 | but could if there ever was a need for it. For reference, here comes a | |
| 75 | non-exhaustive list of specific features: | |
| 76 | ||
| 77 | LM90: | |
| 78 | * Filter and alert configuration register at 0xBF. | |
| 79 | * ALERT is triggered by temperatures over critical limits. | |
| 80 | ||
| 81 | LM86 and LM89: | |
| 82 | * Same as LM90 | |
| 83 | * Better external channel accuracy | |
| 84 | ||
| 85 | LM99: | |
| 86 | * Same as LM89 | |
| 87 | * External temperature shifted by 16 degrees down | |
| 88 | ||
| 89 | ADM1032: | |
| 90 | * Consecutive alert register at 0x22. | |
| 91 | * Conversion averaging. | |
| 92 | * Up to 64 conversions/s. | |
| 93 | * ALERT is triggered by open remote sensor. | |
| 94 | ||
| 95 | ADT7461 | |
| 96 | * Extended temperature range (breaks compatibility) | |
| 97 | * Lower resolution for remote temperature | |
| 98 | ||
| 99 | MAX6657 and MAX6658: | |
| 100 | * Remote sensor type selection | |
| 101 | ||
| 102 | MAX6659 | |
| 103 | * Selectable address | |
| 104 | * Second critical temperature limit | |
| 105 | * Remote sensor type selection | |
| 106 | ||
| 107 | All temperature values are given in degrees Celsius. Resolution | |
| 108 | is 1.0 degree for the local temperature, 0.125 degree for the remote | |
| 109 | temperature. | |
| 110 | ||
| 111 | Each sensor has its own high and low limits, plus a critical limit. | |
| 112 | Additionally, there is a relative hysteresis value common to both critical | |
| 113 | values. To make life easier to user-space applications, two absolute values | |
| 114 | are exported, one for each channel, but these values are of course linked. | |
| 115 | Only the local hysteresis can be set from user-space, and the same delta | |
| 116 | applies to the remote hysteresis. | |
| 117 | ||
| 118 | The lm90 driver will not update its values more frequently than every | |
| 119 | other second; reading them more often will do no harm, but will return | |
| 120 | 'old' values. | |
| 121 |