On Fri, Jun 06, 2025 at 11:11:17AM -0700, Drew Fustini wrote:
> Convert the PMEM device tree binding from text to YAML. This will allow
> device trees with pmem-region nodes to pass dtbs_check.
>
> Acked-by: Conor Dooley <conor.doo...@microchip.com>
> Acked-by: Oliver O'Halloran <ooh...@gmail.com>
> Signed-off-by: Drew Fustini <d...@pdp7.com>
> ---
> Dan/Dave/Vishal: does it make sense for this pmem binding patch to go
> through the nvdimm tree?
>
> Note: checkpatch complains about "DT binding docs and includes should
> be a separate patch". Rob told me that this a false positive. I'm hoping
> that I can fix the false positive at some point if I can remember enough
> perl :)
>
> v3:
> - no functional changes
> - add Oliver's Acked-by
> - bump version to avoid duplicate message-id mess in v2 and v2 resend:
> https://lore.kernel.org/all/20250520021440.24324-1-d...@pdp7.com/
>
> v2 resend:
> - actually put v2 in the Subject
> - add Conor's Acked-by
> - https://lore.kernel.org/all/20250520-refract-fling-d064e11ddbdf@spud/
>
> v2:
> - remove the txt file to make the conversion complete
> - https://lore.kernel.org/all/20250520021440.24324-1-d...@pdp7.com/
>
> v1:
> - https://lore.kernel.org/all/20250518035539.7961-1-d...@pdp7.com/
>
> .../devicetree/bindings/pmem/pmem-region.txt | 65 -------------------
> .../devicetree/bindings/pmem/pmem-region.yaml | 49 ++++++++++++++
> MAINTAINERS | 2 +-
> 3 files changed, 50 insertions(+), 66 deletions(-)
> delete mode 100644 Documentation/devicetree/bindings/pmem/pmem-region.txt
> create mode 100644 Documentation/devicetree/bindings/pmem/pmem-region.yaml
>
> diff --git a/Documentation/devicetree/bindings/pmem/pmem-region.txt
> b/Documentation/devicetree/bindings/pmem/pmem-region.txt
> deleted file mode 100644
> index cd79975e85ec..000000000000
> --- a/Documentation/devicetree/bindings/pmem/pmem-region.txt
> +++ /dev/null
> @@ -1,65 +0,0 @@
> -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;
> - };
> -
> diff --git a/Documentation/devicetree/bindings/pmem/pmem-region.yaml
> b/Documentation/devicetree/bindings/pmem/pmem-region.yaml
> new file mode 100644
> index 000000000000..a4aa4ce3318b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pmem/pmem-region.yaml
> @@ -0,0 +1,49 @@
> +# 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:
> + - Bjorn Helgaas <bhelg...@google.com>
Drop Bjorn. He only did typo fixes on this.
> + - Oliver O'Halloran <ooh...@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: |
Don't need '|' here.
> + 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>;
> + };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index ee93363ec2cb..eba2b81ec568 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13798,7 +13798,7 @@ M: Oliver O'Halloran <ooh...@gmail.com>
> L: nvd...@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
> --
> 2.43.0
>
