From ddc141e5c6be3c5f3f900ba306fe7c7fdb4258cc Mon Sep 17 00:00:00 2001 From: Oliver O'Halloran Date: Fri, 6 Apr 2018 15:21:15 +1000 Subject: [PATCH] doc/devicetree: Persistent memory region bindings Add device-tree binding documentation for the nvdimm region driver. Cc: devicetree@vger.kernel.org Signed-off-by: Oliver O'Halloran Acked-by: Michael Ellerman Signed-off-by: Dan Williams --- .../devicetree/bindings/pmem/pmem-region.txt | 65 +++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 66 insertions(+) create mode 100644 Documentation/devicetree/bindings/pmem/pmem-region.txt diff --git a/Documentation/devicetree/bindings/pmem/pmem-region.txt b/Documentation/devicetree/bindings/pmem/pmem-region.txt new file mode 100644 index 000000000000..5cfa4f016a00 --- /dev/null +++ b/Documentation/devicetree/bindings/pmem/pmem-region.txt @@ -0,0 +1,65 @@ +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 = ; + The reg property should specificy 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 assocativity 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/MAINTAINERS b/MAINTAINERS index 06230c06a071..662a71da42c7 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8041,6 +8041,7 @@ L: linux-nvdimm@lists.01.org Q: https://patchwork.kernel.org/project/linux-nvdimm/list/ S: Supported F: drivers/nvdimm/of_pmem.c +F: Documentation/devicetree/bindings/pmem/pmem-region.txt LIBNVDIMM: NON-VOLATILE MEMORY DEVICE SUBSYSTEM M: Dan Williams