1Kernel driver ntc_thermistor
2=================
3
4Supported thermistors from Murata:
5* Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473,
6  NCP15WL333, NCP03WF104
7  Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473',
8  'ncp15wl333', 'ncp03wf104'
9  Datasheet: Publicly available at Murata
10
11Supported thermistors from EPCOS:
12* EPCOS NTC Thermistors B57330V2103
13  Prefixes: b57330v2103
14  Datasheet: Publicly available at EPCOS
15
16Other NTC thermistors can be supported simply by adding compensation
17tables; e.g., NCP15WL333 support is added by the table ncpXXwl333.
18
19Authors:
20	MyungJoo Ham <myungjoo.ham@samsung.com>
21
22Description
23-----------
24
25The NTC (Negative Temperature Coefficient) thermistor is a simple thermistor
26that requires users to provide the resistance and lookup the corresponding
27compensation table to get the temperature input.
28
29The NTC driver provides lookup tables with a linear approximation function
30and four circuit models with an option not to use any of the four models.
31
32The four circuit models provided are:
33
34	$: resister, [TH]: the thermistor
35
36 1. connect = NTC_CONNECTED_POSITIVE, pullup_ohm > 0
37
38   [pullup_uV]
39       |    |
40      [TH]  $ (pullup_ohm)
41       |    |
42       +----+-----------------------[read_uV]
43       |
44       $ (pulldown_ohm)
45       |
46      --- (ground)
47
48 2. connect = NTC_CONNECTED_POSITIVE, pullup_ohm = 0 (not-connected)
49
50   [pullup_uV]
51       |
52      [TH]
53       |
54       +----------------------------[read_uV]
55       |
56       $ (pulldown_ohm)
57       |
58      --- (ground)
59
60 3. connect = NTC_CONNECTED_GROUND, pulldown_ohm > 0
61
62   [pullup_uV]
63       |
64       $ (pullup_ohm)
65       |
66       +----+-----------------------[read_uV]
67       |    |
68      [TH]  $ (pulldown_ohm)
69       |    |
70      -------- (ground)
71
72 4. connect = NTC_CONNECTED_GROUND, pulldown_ohm = 0 (not-connected)
73
74   [pullup_uV]
75       |
76       $ (pullup_ohm)
77       |
78       +----------------------------[read_uV]
79       |
80      [TH]
81       |
82      --- (ground)
83
84When one of the four circuit models is used, read_uV, pullup_uV, pullup_ohm,
85pulldown_ohm, and connect should be provided. When none of the four models
86are suitable or the user can get the resistance directly, the user should
87provide read_ohm and _not_ provide the others.
88
89Sysfs Interface
90---------------
91name		the mandatory global attribute, the thermistor name.
92
93temp1_type	always 4 (thermistor)
94		RO
95
96temp1_input	measure the temperature and provide the measured value.
97		(reading this file initiates the reading procedure.)
98		RO
99
100Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists.
101