From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver O'Halloran Subject: [PATCH v3 3/4] doc/devicetree: Persistent memory region bindings Date: Fri, 6 Apr 2018 15:21:15 +1000 Message-ID: <20180406052116.31483-3-oohall@gmail.com> References: <20180406052116.31483-1-oohall@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180406052116.31483-1-oohall-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" To: linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org List-Id: devicetree@vger.kernel.org Add device-tree binding documentation for the nvdimm region driver. Cc: devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Signed-off-by: Oliver O'Halloran --- 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 = ; + 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-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.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 -- 2.9.5