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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-07 10:59:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-07 10:59:32 -0700
commit9aa900c8094dba7a60dc805ecec1e9f720744ba1 (patch)
tree3cc09a579f8ea6d3a182076ba722f7c1648e682d /Documentation/w1/slaves/w1_therm.rst
parentMerge tag 'driver-core-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core (diff)
parenthabanalabs: correctly cast u64 to void* (diff)
downloadwireguard-linux-9aa900c8094dba7a60dc805ecec1e9f720744ba1.tar.xz
wireguard-linux-9aa900c8094dba7a60dc805ecec1e9f720744ba1.zip
Merge tag 'char-misc-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH: "Here is the large set of char/misc driver patches for 5.8-rc1 Included in here are: - habanalabs driver updates, loads - mhi bus driver updates - extcon driver updates - clk driver updates (approved by the clock maintainer) - firmware driver updates - fpga driver updates - gnss driver updates - coresight driver updates - interconnect driver updates - parport driver updates (it's still alive!) - nvmem driver updates - soundwire driver updates - visorbus driver updates - w1 driver updates - various misc driver updates In short, loads of different driver subsystem updates along with the drivers as well. All have been in linux-next for a while with no reported issues" * tag 'char-misc-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (233 commits) habanalabs: correctly cast u64 to void* habanalabs: initialize variable to default value extcon: arizona: Fix runtime PM imbalance on error extcon: max14577: Add proper dt-compatible strings extcon: adc-jack: Fix an error handling path in 'adc_jack_probe()' extcon: remove redundant assignment to variable idx w1: omap-hdq: print dev_err if irq flags are not cleared w1: omap-hdq: fix interrupt handling which did show spurious timeouts w1: omap-hdq: fix return value to be -1 if there is a timeout w1: omap-hdq: cleanup to add missing newline for some dev_dbg /dev/mem: Revoke mappings when a driver claims the region misc: xilinx-sdfec: convert get_user_pages() --> pin_user_pages() misc: xilinx-sdfec: cleanup return value in xsdfec_table_write() misc: xilinx-sdfec: improve get_user_pages_fast() error handling nvmem: qfprom: remove incorrect write support habanalabs: handle MMU cache invalidation timeout habanalabs: don't allow hard reset with open processes habanalabs: GAUDI does not support soft-reset habanalabs: add print for soft reset due to event habanalabs: improve MMU cache invalidation code ...
Diffstat (limited to 'Documentation/w1/slaves/w1_therm.rst')
-rw-r--r--Documentation/w1/slaves/w1_therm.rst50
1 files changed, 41 insertions, 9 deletions
diff --git a/Documentation/w1/slaves/w1_therm.rst b/Documentation/w1/slaves/w1_therm.rst
index 90531c340a07..cc4edae17751 100644
--- a/Documentation/w1/slaves/w1_therm.rst
+++ b/Documentation/w1/slaves/w1_therm.rst
@@ -26,20 +26,31 @@ W1_THERM_DS1825 0x3B
W1_THERM_DS28EA00 0x42
==================== ====
-Support is provided through the sysfs w1_slave file. Each open and
+Support is provided through the sysfs w1_slave file. Each open and
read sequence will initiate a temperature conversion then provide two
-lines of ASCII output. The first line contains the nine hex bytes
+lines of ASCII output. The first line contains the nine hex bytes
read along with a calculated crc value and YES or NO if it matched.
-If the crc matched the returned values are retained. The second line
+If the crc matched the returned values are retained. The second line
displays the retained values along with a temperature in millidegrees
Centigrade after t=.
-Parasite powered devices are limited to one slave performing a
-temperature conversion at a time. If none of the devices are parasite
-powered it would be possible to convert all the devices at the same
-time and then go back to read individual sensors. That isn't
-currently supported. The driver also doesn't support reduced
-precision (which would also reduce the conversion time) when reading values.
+Alternatively, temperature can be read using temperature sysfs, it
+return only temperature in millidegrees Centigrade.
+
+A bulk read of all devices on the bus could be done writing 'trigger'
+in the therm_bulk_read sysfs entry at w1_bus_master level. This will
+sent the convert command on all devices on the bus, and if parasite
+powered devices are detected on the bus (and strong pullup is enable
+in the module), it will drive the line high during the longer conversion
+time required by parasited powered device on the line. Reading
+therm_bulk_read will return 0 if no bulk conversion pending,
+-1 if at least one sensor still in conversion, 1 if conversion is complete
+but at least one sensor value has not been read yet. Result temperature is
+then accessed by reading the temperature sysfs entry of each device, which
+may return empty if conversion is still in progress. Note that if a bulk
+read is sent but one sensor is not read immediately, the next access to
+temperature on this device will return the temperature measured at the
+time of issue of the bulk read command (not the current temperature).
Writing a value between 9 and 12 to the sysfs w1_slave file will change the
precision of the sensor for the next readings. This value is in (volatile)
@@ -49,6 +60,27 @@ To store the current precision configuration into EEPROM, the value 0
has to be written to the sysfs w1_slave file. Since the EEPROM has a limited
amount of writes (>50k), this command should be used wisely.
+Alternatively, resolution can be set or read (value from 9 to 12) using the
+dedicated resolution sysfs entry on each device. This sysfs entry is not
+present for devices not supporting this feature. Driver will adjust the
+correct conversion time for each device regarding to its resolution setting.
+In particular, strong pullup will be applied if required during the conversion
+duration.
+
+The write-only sysfs entry eeprom is an alternative for EEPROM operations:
+ * 'save': will save device RAM to EEPROM
+ * 'restore': will restore EEPROM data in device RAM.
+
+ext_power syfs entry allow tho check the power status of each device.
+ * '0': device parasite powered
+ * '1': device externally powered
+
+sysfs alarms allow read or write TH and TL (Temperature High an Low) alarms.
+Values shall be space separated and in the device range (typical -55 degC
+to 125 degC). Values are integer as they are store in a 8bit register in
+the device. Lowest value is automatically put to TL.Once set, alarms could
+be search at master level.
+
The module parameter strong_pullup can be set to 0 to disable the
strong pullup, 1 to enable autodetection or 2 to force strong pullup.
In case of autodetection, the driver will use the "READ POWER SUPPLY"