Documentation/ABI/testing/sysfs-driver-w1_therm

Source file repositories/reference/linux-study-clean/Documentation/ABI/testing/sysfs-driver-w1_therm

File Facts

System
Linux kernel
Corpus path
Documentation/ABI/testing/sysfs-driver-w1_therm
Extension
[no extension]
Size
6492 bytes
Lines
191
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: Documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

What:		/sys/bus/w1/devices/.../alarms
Date:		May 2020
Contact:	Akira Shimahara <akira215corp@gmail.com>
Description:
		(RW) 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), if not values will be trimmed
		to device min/max capabilities. Values are integer as they are
		stored in a 8bit register in the device. Lowest value is
		automatically put to TL. Once set, alarms could be search at
		master level, refer to Documentation/w1/w1-generic.rst for
		detailed information
Users:		any user space application which wants to communicate with
		w1_term device


What:		/sys/bus/w1/devices/.../eeprom_cmd
Date:		May 2020
Contact:	Akira Shimahara <akira215corp@gmail.com>
Description:
		(WO) writing that file will either trigger a save of the
		device data to its embedded EEPROM, either restore data
		embedded in device EEPROM. Be aware that devices support
		limited EEPROM writing cycles (typical 50k)

			* 'save': save device RAM to EEPROM
			* 'restore': restore EEPROM data in device RAM

Users:		any user space application which wants to communicate with
		w1_term device


What:		/sys/bus/w1/devices/.../ext_power
Date:		May 2020
Contact:	Akira Shimahara <akira215corp@gmail.com>
Description:
		(RO) return the power status by asking the device

			* '0': device parasite powered
			* '1': device externally powered
			* '-xx': xx is kernel error when reading power status

Users:		any user space application which wants to communicate with
		w1_term device


What:		/sys/bus/w1/devices/.../resolution
Date:		May 2020
Contact:	Akira Shimahara <akira215corp@gmail.com>
Description:
		(RW) get or set the device resolution (on supported devices,
		if not, this entry is not present). Note that the resolution
		will be changed only in device RAM, so it will be cleared when
		power is lost. Trigger a 'save' to EEPROM command to keep
		values after power-on. Read or write are :

			* '9..14': device resolution in bit
			  or resolution to set in bit
			* '-xx': xx is kernel error when reading the resolution
			* Anything else: do nothing

		Some DS18B20 clones are fixed in 12-bit resolution, so the
		actual resolution is read back from the chip and verified. Error
		is reported if the results differ.
Users:		any user space application which wants to communicate with
		w1_term device


What:		/sys/bus/w1/devices/.../temperature
Date:		May 2020

Annotation

Implementation Notes