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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 | |||