Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD

Source file repositories/reference/linux-study-clean/Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD

File Facts

System
Linux kernel
Corpus path
Documentation/ABI/testing/sysfs-devices-platform-ACPI-TAD
Extension
[no extension]
Size
4189 bytes
Lines
118
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

ACPI Time and Alarm (TAD) device attributes.

What:		/sys/bus/platform/devices/ACPI000E:00/caps
Date:		March 2018
Contact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Description:
		(RO) Hexadecimal bitmask of the TAD attributes are reported by
		the platform firmware (see ACPI 6.2, section 9.18.2):

		======= ======================================================
		BIT(0): AC wakeup implemented if set
		BIT(1): DC wakeup implemented if set
		BIT(2): Get/set real time features implemented if set
		BIT(3): Real time accuracy in milliseconds if set
		BIT(4): Correct status reported for wakeups from S4/S5 if set
		BIT(5): The AC timer wakes up from S4 if set
		BIT(6): The AC timer wakes up from S5 if set
		BIT(7): The DC timer wakes up from S4 if set
		BIT(8): The DC timer wakes up from S5 if set
		======= ======================================================

		The other bits are reserved.

What:		/sys/bus/platform/devices/ACPI000E:00/ac_alarm
Date:		March 2018
Contact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Description:
		(RW) The AC alarm timer value.

		Reads return the current AC alarm timer value in seconds or
		"disabled", if the AC alarm is not set to wake up the system.

		Write a new AC alarm timer value in seconds or "disabled" to it
		to set the AC alarm timer or to disable it, respectively.

		If the AC alarm timer is set through this attribute and it
		expires, it will immediately wake up the system from the S3
		sleep state (and from S4/S5 too if supported) until its status
		is explicitly cleared via the ac_status attribute.

What:		/sys/bus/platform/devices/ACPI000E:00/ac_policy
Date:		March 2018
Contact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Description:
		(RW) The AC alarm expired timer wake policy (see ACPI 6.2,
		Section 9.18 for details).

		Reads return the current expired timer wake delay for the AC
		alarm timer or "never", if the policy is to discard AC timer
		wakeups if the system is on DC power.

		Write a new expired timer wake delay for the AC alarm timer in
		seconds or "never" to it to set the expired timer wake delay for
		the AC alarm timer or to set its expired wake policy to discard
		wakeups if the system is on DC power, respectively.

What:		/sys/bus/platform/devices/ACPI000E:00/ac_status
Date:		March 2018
Contact:	Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Description:
		(RW) The AC alarm status.

		Reads return a hexadecimal bitmask representing the AC alarm
		timer status with the following meaning of bits (see ACPI 6.2,
		Section 9.18.5):

		======= ======================================================
		Bit(0): The timer has expired if set.
		Bit(1): The timer has woken up the system from a sleep state
		        (S3 or S4/S5 if supported) if set.

Annotation

Implementation Notes