Documentation/ABI/testing/sysfs-bus-cxl

What:		/sys/bus/cxl/devices/memX/firmware_version
Date:		December, 2020
KernelVersion:	v5.12
Contact:	linux-cxl@vger.kernel.org
Description:
		(RO) "FW Revision" string as reported by the Identify
		Memory Device Output Payload in the CXL-2.0
		specification.

What:		/sys/bus/cxl/devices/memX/ram/size
Date:		December, 2020
KernelVersion:	v5.12
Contact:	linux-cxl@vger.kernel.org
Description:
		(RO) "Volatile Only Capacity" as bytes. Represents the
		identically named field in the Identify Memory Device Output
		Payload in the CXL-2.0 specification.

What:		/sys/bus/cxl/devices/memX/pmem/size
Date:		December, 2020
KernelVersion:	v5.12
Contact:	linux-cxl@vger.kernel.org
Description:
		(RO) "Persistent Only Capacity" as bytes. Represents the
		identically named field in the Identify Memory Device Output
		Payload in the CXL-2.0 specification.

What:		/sys/bus/cxl/devices/*/devtype
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		CXL device objects export the devtype attribute which mirrors
		the same value communicated in the DEVTYPE environment variable
		for uevents for devices on the "cxl" bus.

What:		/sys/bus/cxl/devices/portX/uport
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		CXL port objects are enumerated from either a platform firmware
		device (ACPI0017 and ACPI0016) or PCIe switch upstream port with
		CXL component registers. The 'uport' symlink connects the CXL
		portX object to the device that published the CXL port
		capability.

What:		/sys/bus/cxl/devices/portX/dportY
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		CXL port objects are enumerated from either a platform firmware
		device (ACPI0017 and ACPI0016) or PCIe switch upstream port with
		CXL component registers. The 'dportY' symlink identifies one or
		more downstream ports that the upstream port may target in its
		decode of CXL memory resources.  The 'Y' integer reflects the
		hardware port unique-id used in the hardware decoder target
		list.

What:		/sys/bus/cxl/devices/decoderX.Y
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		CXL decoder objects are enumerated from either a platform
		firmware description, or a CXL HDM decoder register set in a
		PCIe device (see CXL 2.0 section 8.2.5.12 CXL HDM Decoder
		Capability Structure). The 'X' in decoderX.Y represents the
		cxl_port container of this decoder, and 'Y' represents the
		instance id of a given decoder resource.

What:		/sys/bus/cxl/devices/decoderX.Y/{start,size}
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		The 'start' and 'size' attributes together convey the physical
		address base and number of bytes mapped in the decoder's decode
		window. For decoders of devtype "cxl_decoder_root" the address
		range is fixed. For decoders of devtype "cxl_decoder_switch" the
		address is bounded by the decode range of the cxl_port ancestor
		of the decoder's cxl_port, and dynamically updates based on the
		active memory regions in that address space.

What:		/sys/bus/cxl/devices/decoderX.Y/locked
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		CXL HDM decoders have the capability to lock the configuration
		until the next device reset. For decoders of devtype
		"cxl_decoder_root" there is no standard facility to unlock them.
		For decoders of devtype "cxl_decoder_switch" a secondary bus
		reset, of the PCIe bridge that provides the bus for this
		decoders uport, unlocks / resets the decoder.

What:		/sys/bus/cxl/devices/decoderX.Y/target_list
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		Display a comma separated list of the current decoder target
		configuration. The list is ordered by the current configured
		interleave order of the decoder's dport instances. Each entry in
		the list is a dport id.

What:		/sys/bus/cxl/devices/decoderX.Y/cap_{pmem,ram,type2,type3}
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		When a CXL decoder is of devtype "cxl_decoder_root", it
		represents a fixed memory window identified by platform
		firmware. A fixed window may only support a subset of memory
		types. The 'cap_*' attributes indicate whether persistent
		memory, volatile memory, accelerator memory, and / or expander
		memory may be mapped behind this decoder's memory window.

What:		/sys/bus/cxl/devices/decoderX.Y/target_type
Date:		June, 2021
KernelVersion:	v5.14
Contact:	linux-cxl@vger.kernel.org
Description:
		When a CXL decoder is of devtype "cxl_decoder_switch", it can
		optionally decode either accelerator memory (type-2) or expander
		memory (type-3). The 'target_type' attribute indicates the
		current setting which may dynamically change based on what
		memory regions are activated in this decode hierarchy.