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