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authorLinus Torvalds <torvalds@linux-foundation.org>2024-01-13 00:27:40 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2024-01-13 00:27:40 +0300
commit5dfec3cf3efbd897d774e3b5c08c2f0deaf9b5ad (patch)
treedf527b523e97fba2c54ba409468575a027225638 /Documentation/hwmon/max31827.rst
parent7912a6391f3ee7eb9f9a69227a209d502679bc0c (diff)
parent41c71105a845ec1458680f01644d032a5fbbe0d9 (diff)
downloadlinux-5dfec3cf3efbd897d774e3b5c08c2f0deaf9b5ad.tar.xz
Merge tag 'hwmon-for-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging
Pull hwmon updates from Guenter Roeck: "New drivers: - pmbus: Support for MPS Multi-phase mp2856/mp2857 controller - pmbus: Support for MPS Multi-phase mp5990 - Driver for Gigabyte AORUS Waterforce AIO coolers Added support to existing drivers: - lm75: Support for AMS AS6200 temperature sensor - k10temp: Support for AMD Family 19h Model 8h - max31827: Support for max31828 and max31829 - sht3x: Support for sts3x - Add support for WMI SMM interface, and various related improvements. Add support for Optiplex 7000 - emc1403: Support for EMC1442 - npcm750-pwm-fan: Support for NPCM8xx - nct6775: Add support for 2 additional fan controls Minor improvements and bug fixes: - gigabyte_waterforce: Mark status report as received under a spinlock - aquacomputer_d5next: Remove unneeded CONFIG_DEBUG_FS #ifdef - gpio-fan: Convert txt bindings to yaml - smsc47m1: Various cleanups / improvements - corsair-cpro: use NULL instead of 0 - hp-wmi-sensors: Fix failure to load on EliteDesk 800 G6 - tmp513: Various cleanups - peci/dimmtemp: Bump timeout - pc87360: Bounds check data->innr usage - nct6775: Fix fan speed set failure in automatic mode - ABI: sysfs-class-hwmon: document various missing attributes - lm25066, max6650, nct6775: Use i2c_get_match_data() - aspeed-pwm-tacho: Fix -Wstringop-overflow warning" * tag 'hwmon-for-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging: (59 commits) hwmon: (gigabyte_waterforce) Mark status report as received under a spinlock hwmon: (lm75) Fix tmp112 default config hwmon: (lm75) Add AMS AS6200 temperature sensor dt-bindings: hwmon: (lm75) Add AMS AS6200 temperature sensor hwmon: (lm75) remove now-unused include hwmon: (pmbus) Add support for MPS Multi-phase mp2856/mp2857 controller dt-bindings: Add MP2856/MP2857 voltage regulator device hwmon: (aquacomputer_d5next) Remove unneeded CONFIG_DEBUG_FS #ifdef dt-bindings: hwmon: gpio-fan: Convert txt bindings to yaml hwmon: (k10temp) Add support for AMD Family 19h Model 8h hwmon: Add driver for Gigabyte AORUS Waterforce AIO coolers hwmon: (smsc47m1) Rename global platform device variable hwmon: (smsc47m1) Simplify device registration hwmon: (smsc47m1) Convert to platform remove callback returning void hwmon: (smsc47m1) Mark driver struct with __refdata to prevent section mismatch MAINTAINERS: Add maintainer for Baikal-T1 PVT hwmon driver hwmon: (sht3x) add sts3x support hwmon: (pmbus) Add ltc4286 driver dt-bindings: hwmon: Add lltc ltc4286 driver bindings hwmon: (max31827) Add custom attribute for resolution ...
Diffstat (limited to 'Documentation/hwmon/max31827.rst')
-rw-r--r--Documentation/hwmon/max31827.rst75
1 files changed, 61 insertions, 14 deletions
diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst
index 9a1055a007cf..44ab9dc064cb 100644
--- a/Documentation/hwmon/max31827.rst
+++ b/Documentation/hwmon/max31827.rst
@@ -52,13 +52,21 @@ MAX31827 has low and over temperature alarms with an effective value and a
hysteresis value: -40 and -30 degrees for under temperature alarm and +100 and
+90 degrees for over temperature alarm.
-The alarm can be configured in comparator and interrupt mode. Currently only
-comparator mode is implemented. In Comparator mode, the OT/UT status bits have a
-value of 1 when the temperature rises above the TH value or falls below TL,
-which is also subject to the Fault Queue selection. OT status returns to 0 when
-the temperature drops below the TH_HYST value or when shutdown mode is entered.
-Similarly, UT status returns to 0 when the temperature rises above TL_HYST value
-or when shutdown mode is entered.
+The alarm can be configured in comparator and interrupt mode from the
+devicetree. In Comparator mode, the OT/UT status bits have a value of 1 when the
+temperature rises above the TH value or falls below TL, which is also subject to
+the Fault Queue selection. OT status returns to 0 when the temperature drops
+below the TH_HYST value or when shutdown mode is entered. Similarly, UT status
+returns to 0 when the temperature rises above TL_HYST value or when shutdown
+mode is entered.
+
+In interrupt mode exceeding TH also sets OT status to 1, which remains set until
+a read operation is performed on the configuration/status register (max or min
+attribute); at this point, it returns to 0. Once OT status is set to 1 from
+exceeding TH and reset, it is set to 1 again only when the temperature drops
+below TH_HYST. The output remains asserted until it is reset by a read. It is
+set again if the temperature rises above TH, and so on. The same logic applies
+to the operation of the UT status bit.
Putting the MAX31827 into shutdown mode also resets the OT/UT status bits. Note
that if the mode is changed while OT/UT status bits are set, an OT/UT status
@@ -68,13 +76,42 @@ clear the status bits before changing the operating mode.
The conversions can be manual with the one-shot functionality and automatic with
a set frequency. When powered on, the chip measures temperatures with 1 conv/s.
+The conversion rate can be modified with update_interval attribute of the chip.
+Conversion/second = 1/update_interval. Thus, the available options according to
+the data sheet are:
+
+- 64000 (ms) = 1 conv/64 sec
+- 32000 (ms) = 1 conv/32 sec
+- 16000 (ms) = 1 conv/16 sec
+- 4000 (ms) = 1 conv/4 sec
+- 1000 (ms) = 1 conv/sec (default)
+- 250 (ms) = 4 conv/sec
+- 125 (ms) = 8 conv/sec
+
Enabling the device when it is already enabled has the side effect of setting
the conversion frequency to 1 conv/s. The conversion time varies depending on
-the resolution. The conversion time doubles with every bit of increased
-resolution. For 10 bit resolution 35ms are needed, while for 12 bit resolution
-(default) 140ms. When chip is in shutdown mode and a read operation is
-requested, one-shot is triggered, the device waits for 140 (conversion time) ms,
-and only after that is the temperature value register read.
+the resolution.
+
+The conversion time doubles with every bit of increased resolution. The
+available resolutions are:
+
+- 8 bit -> 8.75 ms conversion time
+- 9 bit -> 17.5 ms conversion time
+- 10 bit -> 35 ms conversion time
+- 12 bit (default) -> 140 ms conversion time
+
+There is a temp1_resolution attribute which indicates the unit change in the
+input temperature in milli-degrees C.
+
+- 1000 mC -> 8 bit
+- 500 mC -> 9 bit
+- 250 mC -> 10 bit
+- 62 mC -> 12 bit (default) - actually this is 62.5, but the fil returns 62
+
+When chip is in shutdown mode and a read operation is requested, one-shot is
+triggered, the device waits for <conversion time> ms, and only after that is
+the temperature value register read. Note that the conversion times are rounded
+up to the nearest possible integer.
The LSB of the temperature values is 0.0625 degrees Celsius, but the values of
the temperatures are displayed in milli-degrees. This means, that some data is
@@ -83,8 +120,18 @@ in the writing of alarm values too. For positive numbers the user-input value
will always be rounded down to the nearest possible value, for negative numbers
the user-input will always be rounded up to the nearest possible value.
+Bus timeout resets the I2C-compatible interface when SCL is low for more than
+30ms (nominal).
+
+Alarm polarity determines if the active state of the alarm is low or high. The
+behavior for both settings is dependent on the Fault Queue setting. The ALARM
+pin is an open-drain output and requires a pullup resistor to operate.
+
+The Fault Queue bits select how many consecutive temperature faults must occur
+before overtemperature or undertemperature faults are indicated in the
+corresponding status bits.
+
Notes
-----
-Currently fault queue, alarm polarity and resolution cannot be modified.
-PEC is not implemented either.
+PEC is not implemented.