Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 100 insertions, 0 deletions

diff --git a/Documentation/hwmon/ntc_thermistor b/Documentation/hwmon/ntc_thermistor
new file mode 100644
index 000000000..8b9ff23ed
--- /dev/null
+++ b/Documentation/hwmon/ntc_thermistor
@@ -0,0 +1,100 @@
+Kernel driver ntc_thermistor
+=================
+
+Supported thermistors from Murata:
+* Murata NTC Thermistors NCP15WB473, NCP18WB473, NCP21WB473, NCP03WB473,
+  NCP15WL333, NCP03WF104, NCP15XH103
+  Prefixes: 'ncp15wb473', 'ncp18wb473', 'ncp21wb473', 'ncp03wb473',
+  'ncp15wl333', 'ncp03wf104', 'ncp15xh103'
+  Datasheet: Publicly available at Murata
+
+Supported thermistors from EPCOS:
+* EPCOS NTC Thermistors B57330V2103
+  Prefixes: b57330v2103
+  Datasheet: Publicly available at EPCOS
+
+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 (Negative Temperature Coefficient) 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.