summaryrefslogtreecommitdiffstats
path: root/Documentation/hwmon/emc1403.rst
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/hwmon/emc1403.rst')
-rw-r--r--Documentation/hwmon/emc1403.rst80
1 files changed, 80 insertions, 0 deletions
diff --git a/Documentation/hwmon/emc1403.rst b/Documentation/hwmon/emc1403.rst
new file mode 100644
index 000000000..0de9616b2
--- /dev/null
+++ b/Documentation/hwmon/emc1403.rst
@@ -0,0 +1,80 @@
+Kernel driver emc1403
+=====================
+
+Supported chips:
+
+ * SMSC / Microchip EMC1402, EMC1412
+
+ Addresses scanned: I2C 0x18, 0x1c, 0x29, 0x4c, 0x4d, 0x5c
+
+ Prefix: 'emc1402'
+
+ Datasheets:
+
+ - http://ww1.microchip.com/downloads/en/DeviceDoc/1412.pdf
+ - https://ww1.microchip.com/downloads/en/DeviceDoc/1402.pdf
+
+ * SMSC / Microchip EMC1403, EMC1404, EMC1413, EMC1414
+
+ Addresses scanned: I2C 0x18, 0x29, 0x4c, 0x4d
+
+ Prefix: 'emc1403', 'emc1404'
+
+ Datasheets:
+
+ - http://ww1.microchip.com/downloads/en/DeviceDoc/1403_1404.pdf
+ - http://ww1.microchip.com/downloads/en/DeviceDoc/1413_1414.pdf
+
+ * SMSC / Microchip EMC1422
+
+ Addresses scanned: I2C 0x4c
+
+ Prefix: 'emc1422'
+
+ Datasheet:
+
+ - https://ww1.microchip.com/downloads/en/DeviceDoc/1422.pdf
+
+ * SMSC / Microchip EMC1423, EMC1424
+
+ Addresses scanned: I2C 0x4c
+
+ Prefix: 'emc1423', 'emc1424'
+
+ Datasheet:
+
+ - https://ww1.microchip.com/downloads/en/DeviceDoc/1423_1424.pdf
+
+Author:
+ Kalhan Trisal <kalhan.trisal@intel.com
+
+
+Description
+-----------
+
+The Standard Microsystems Corporation (SMSC) / Microchip EMC14xx chips
+contain up to four temperature sensors. EMC14x2 support two sensors
+(one internal, one external). EMC14x3 support three sensors (one internal,
+two external), and EMC14x4 support four sensors (one internal, three
+external).
+
+The chips implement three limits for each sensor: low (tempX_min), high
+(tempX_max) and critical (tempX_crit.) The chips also implement an
+hysteresis mechanism which applies to all 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 three 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.
+* The hysteresis values can't be set independently. We decided to make
+ only temp1_crit_hyst writable, while all other hysteresis attributes
+ 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 all other limits.
+* The limits should be set before the hysteresis.