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authorLinus Torvalds <torvalds@linux-foundation.org>2019-05-06 19:56:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-05-06 19:56:51 -0700
commit7aefd944f038c7469571adb37769cb6f3924ecfa (patch)
treef0a8dc23633b6bbbc4f0bff932f332e847fb6c1b /Documentation/hwmon/lm77.rst
parentMerge branch 'ras-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (diff)
parenthwmon: (lm75) Add support for TMP75B (diff)
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Merge tag 'hwmon-for-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging
Pull hwmon updates from Guenter Roeck: - Add driver for Intersil ISL68137 PWM Controller - Add driver for Lochnagar 2 - Add driver for Infineon IR38064 Voltage Regulator - Add support for TMP75B to lm75 driver - Convert documentation to ReST format - Use request_muxed_region for Super-IO accesses in several drivers - Add 'samples' attribute to ABI, and start using it - Add support for custom sysfs attributes to pmbus drivers (used in ISL68137 driver) - Introduce HWMON_CHANNEL_INFO macro - Automated changes: - Use permission specific [SENSOR_][DEVICE_]ATTR variants - Fix build warnings due to unused of_device_id structures - Use HWMON_CHANNEL_INFO macro - Various minor improvements and fixes * tag 'hwmon-for-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging: (125 commits) hwmon: (lm75) Add support for TMP75B dt-bindings: hwmon: Add tmp75b to lm75.txt hwmon: (s3c) Use dev_get_drvdata() hwmon: (max6650) Drop call to thermal_cdev_update docs: hwmon: remove the extension from .rst files docs: hwmon: convert three docs to ReST format hwmon: (max6650) add thermal cooling device capability hwmon: (ina3221) Add voltage conversion time settings hwmon: (ina3221) Do not read-back to cache reg_config docs: hwmon: Add an index file and rename docs to *.rst docs: hwmon: convert remaining files to ReST format docs: hwmon: misc files: convert to ReST format docs: hwmon: pmbus files: convert to ReST format docs: hwmon: k8temp, w83793: convert to ReST format docs: hwmon: da9052, da9055: convert to ReST format docs: hwmon: wm831x, wm8350: convert to ReST format docs: hwmon: dme1737, vt1211: convert to ReST format docs: hwmon: ads1015: convert to ReST format docs: hwmon: asc7621: convert to ReST format docs: hwmon: ibmpowernv: convert to ReST format ...
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+Kernel driver lm77
+==================
+
+Supported chips:
+
+ * National Semiconductor LM77
+
+ Prefix: 'lm77'
+
+ Addresses scanned: I2C 0x48 - 0x4b
+
+ Datasheet: Publicly available at the National Semiconductor website
+
+ http://www.national.com/
+
+
+Author: Andras BALI <drewie@freemail.hu>
+
+Description
+-----------
+
+The LM77 implements one temperature sensor. The temperature
+sensor incorporates a band-gap type temperature sensor,
+10-bit ADC, and a digital comparator with user-programmable upper
+and lower limit values.
+
+The LM77 implements 3 limits: low (temp1_min), high (temp1_max) and
+critical (temp1_crit.) It also implements an hysteresis mechanism which
+applies to all 3 limits. The relative difference is stored in a single
+register on the chip, which means that the relative difference between
+the limit and its hysteresis is always the same for all 3 limits.
+
+This implementation detail implies the following:
+
+* When setting a limit, its hysteresis will automatically follow, the
+ difference staying unchanged. For example, if the old critical limit
+ was 80 degrees C, and the hysteresis was 75 degrees C, and you change
+ the critical limit to 90 degrees C, then the hysteresis will
+ automatically change to 85 degrees C.
+* All 3 hysteresis can't be set independently. We decided to make
+ temp1_crit_hyst writable, while temp1_min_hyst and temp1_max_hyst are
+ read-only. Setting temp1_crit_hyst writes the difference between
+ temp1_crit_hyst and temp1_crit into the chip, and the same relative
+ hysteresis applies automatically to the low and high limits.
+* The limits should be set before the hysteresis.