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authorLinus Torvalds <torvalds@linux-foundation.org>2011-07-30 08:57:57 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-30 08:57:57 -1000
commit464c9098bbc17b4596aa12191a7e646a28e7587a (patch)
tree1d97f02c1f071f358f0d0b5fd8e04db3b9a7a9af /Documentation/hwmon/ntc_thermistor
parent4c677e2eefdba9c5bfc4474e2e91b26ae8458a1d (diff)
parentf90be42fb383f39aa814b8e14de138da8973e5c1 (diff)
Merge branch 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/staging
* 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/staging: (24 commits) hwmon: (lm90) Refactor reading of config2 register hwmon: (lm90) Make SA56004 detection more robust hwmon: (lm90) Simplify handling of extended local temp register hwmon: (pmbus) Add client driver for LM25066, LM5064, and LM5066 hwmon: (max34440) Add support for peak attributes hwmon: (max8688) Add support for peak attributes hwmon: (max16064) Add support for peak attributes hwmon: (adm1275) Add support for peak attributes hwmon: (pmbus) Add support for peak attributes hwmon: Add new attributes to sysfs ABI hwmon: (pmbus) Strengthen check for status register existence hwmon: (pmbus) Add support for virtual pages hwmon: (pmbus) Support reading and writing of word registers in device specific code hwmon: (pmbus) Increase attribute name size hwmon: (pmbus) Add ADP4000, NCP4200 and NCP4208 to list of supported devices hwmon: (pmbus) Add support for VID output voltage mode hwmon: (pmbus) Move PMBus drivers to drivers/hwmon/pmbus hwmon: (coretemp) Add core/pkg threshold support to Coretemp hwmon: (lm95241) Add support for LM95231 hwmon: LM95245 driver ...
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+Kernel driver ntc_thermistor
+=================
+
+Supported thermistors:
+* Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473, NCP15WL333
+ Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473', 'ncp15wl333'
+ Datasheet: Publicly available at Murata
+
+Other NTC thermistors can be supported simply by adding compensation
+tables; e.g., NCP15WL333 support is added by the table ncpXXwl333.
+
+Authors:
+ MyungJoo Ham <myungjoo.ham@samsung.com>
+
+Description
+-----------
+
+The NTC thermistor is a simple thermistor that requires users to provide the
+resistance and lookup the corresponding compensation table to get the
+temperature input.
+
+The NTC driver provides lookup tables with a linear approximation function
+and four circuit models with an option not to use any of the four models.
+
+The four circuit models provided are:
+
+ $: resister, [TH]: the thermistor
+
+ 1. connect = NTC_CONNECTED_POSITIVE, pullup_ohm > 0
+
+ [pullup_uV]
+ | |
+ [TH] $ (pullup_ohm)
+ | |
+ +----+-----------------------[read_uV]
+ |
+ $ (pulldown_ohm)
+ |
+ --- (ground)
+
+ 2. connect = NTC_CONNECTED_POSITIVE, pullup_ohm = 0 (not-connected)
+
+ [pullup_uV]
+ |
+ [TH]
+ |
+ +----------------------------[read_uV]
+ |
+ $ (pulldown_ohm)
+ |
+ --- (ground)
+
+ 3. connect = NTC_CONNECTED_GROUND, pulldown_ohm > 0
+
+ [pullup_uV]
+ |
+ $ (pullup_ohm)
+ |
+ +----+-----------------------[read_uV]
+ | |
+ [TH] $ (pulldown_ohm)
+ | |
+ -------- (ground)
+
+ 4. connect = NTC_CONNECTED_GROUND, pulldown_ohm = 0 (not-connected)
+
+ [pullup_uV]
+ |
+ $ (pullup_ohm)
+ |
+ +----------------------------[read_uV]
+ |
+ [TH]
+ |
+ --- (ground)
+
+When one of the four circuit models is used, read_uV, pullup_uV, pullup_ohm,
+pulldown_ohm, and connect should be provided. When none of the four models
+are suitable or the user can get the resistance directly, the user should
+provide read_ohm and _not_ provide the others.
+
+Sysfs Interface
+---------------
+name the mandatory global attribute, the thermistor name.
+
+temp1_type always 4 (thermistor)
+ RO
+
+temp1_input measure the temperature and provide the measured value.
+ (reading this file initiates the reading procedure.)
+ RO
+
+Note that each NTC thermistor has only _one_ thermistor; thus, only temp1 exists.