Merge tag 'libnvdimm-fixes-6.16-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Device-tree bindings for persistent memory regions

-----------------------------------------------------

Persistent memory refers to a class of memory devices that are:

	a) Usable as main system memory (i.e. cacheable), and

	b) Retain their contents across power failure.

Given b) it is best to think of persistent memory as a kind of memory mapped

storage device. To ensure data integrity the operating system needs to manage

persistent regions separately to the normal memory pool. To aid with that this

binding provides a standardised interface for discovering where persistent

memory regions exist inside the physical address space.

Bindings for the region nodes:

-----------------------------

Required properties:

	- compatible = "pmem-region"

	- reg = <base, size>;

		The reg property should specify an address range that is

		translatable to a system physical address range. This address

		range should be mappable as normal system memory would be

		(i.e cacheable).

		If the reg property contains multiple address ranges

		each address range will be treated as though it was specified

		in a separate device node. Having multiple address ranges in a

		node implies no special relationship between the two ranges.

Optional properties:

	- Any relevant NUMA associativity properties for the target platform.

	- volatile; This property indicates that this region is actually

	  backed by non-persistent memory. This lets the OS know that it

	  may skip the cache flushes required to ensure data is made

	  persistent after a write.

	  If this property is absent then the OS must assume that the region

	  is backed by non-volatile memory.

Examples:

--------------------

	/*

	 * This node specifies one 4KB region spanning from

	 * 0x5000 to 0x5fff that is backed by non-volatile memory.

	 */

	pmem@5000 {

		compatible = "pmem-region";

		reg = <0x00005000 0x00001000>;

	};

	/*

	 * This node specifies two 4KB regions that are backed by

	 * volatile (normal) memory.

	 */

	pmem@6000 {

		compatible = "pmem-region";

		reg = < 0x00006000 0x00001000

			0x00008000 0x00001000 >;

		volatile;

	};

# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)

%YAML 1.2

---

$id: http://devicetree.org/schemas/pmem-region.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#

maintainers:

  - Oliver O'Halloran <oohall@gmail.com>

title: Persistent Memory Regions

description: |

  Persistent memory refers to a class of memory devices that are:

    a) Usable as main system memory (i.e. cacheable), and

    b) Retain their contents across power failure.

  Given b) it is best to think of persistent memory as a kind of memory mapped

  storage device. To ensure data integrity the operating system needs to manage

  persistent regions separately to the normal memory pool. To aid with that this

  binding provides a standardised interface for discovering where persistent

  memory regions exist inside the physical address space.

properties:

  compatible:

    const: pmem-region

  reg:

    maxItems: 1

  volatile:

    description:

      Indicates the region is volatile (non-persistent) and the OS can skip

      cache flushes for writes

    type: boolean

required:

  - compatible

  - reg

additionalProperties: false

examples:

  - |

    pmem@5000 {

        compatible = "pmem-region";

        reg = <0x00005000 0x00001000>;

    };

L:	nvdimm@lists.linux.dev

S:	Supported

Q:	https://patchwork.kernel.org/project/linux-nvdimm/list/

F:	Documentation/devicetree/bindings/pmem/pmem-region.txt

F:	Documentation/devicetree/bindings/pmem/pmem-region.yaml

F:	drivers/nvdimm/of_pmem.c

LIBNVDIMM: NON-VOLATILE MEMORY DEVICE SUBSYSTEM