Add device-tree binding documentation for the nvdimm region driver.
Cc: devicetree@xxxxxxxxxxxxxxx
Signed-off-by: Oliver O'Halloran <oohall@xxxxxxxxx>
---
v2: Changed name from nvdimm-region to pmem-region.
Cleaned up the example binding and fixed the overlapping regions.
Added support for multiple regions in a single reg.
v3: Removed platform bus boilerplate from the example.
Changed description of the volatile and reg properties
to make them more clear.
---
.../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 = <base, size>;
+ 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 df240740ca78..cbd289d58644 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8020,6 +8020,7 @@ L: linux-nvdimm@xxxxxxxxxxxx
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 <dan.j.williams@xxxxxxxxx>
--
2.9.5
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