[RFC PATCH v4 2/4] Documentation: arm64/arm: dt bindings for numa.

[Ganapatrao Kulkarni]

DT bindings for numa map for memory, cores and IOs using
arm,associativity device node property.

Signed-off-by: Ganapatrao Kulkarni <gkulkarni at caviumnetworks.com>
---
 Documentation/devicetree/bindings/arm/numa.txt | 212 +++++++++++++++++++++++++
 1 file changed, 212 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/numa.txt

diff --git a/Documentation/devicetree/bindings/arm/numa.txt b/Documentation/devicetree/bindings/arm/numa.txt
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+==============================================================================
+NUMA binding description.
+==============================================================================
+
+==============================================================================
+1 - Introduction
+==============================================================================
+
+Systems employing a Non Uniform Memory Access (NUMA) architecture contain
+collections of hardware resources including processors, memory, and I/O buses,
+that comprise what is commonly known as a NUMA node.
+Processor accesses to memory within the local NUMA node is generally faster
+than processor accesses to memory outside of the local NUMA node.
+DT defines interfaces that allow the platform to convey NUMA node
+topology information to OS.
+
+==============================================================================
+2 - arm,associativity
+==============================================================================
+The mapping is done using arm,associativity device property.
+this property needs to be present in every device node which needs to to be
+mapped to numa nodes.
+
+arm,associativity property is set of 32-bit integers which defines level of
+topology and boundary in the system at which a significant difference in
+performance can be measured between cross-device accesses within
+a single location and those spanning multiple locations.
+The first cell always contains the broadest subdivision within the system,
+while the last cell enumerates the individual devices, such as an SMT thread
+of a CPU, or a bus bridge within an SoC".
+
+ex:
+	/* board 0, socket 0, cluster 0, core 0  thread 0 */
+	arm,associativity = <0 0 0 0 0>;
+
+==============================================================================
+3 - arm,associativity-reference-points
+==============================================================================
+This property is a set of 32-bit integers, each representing an index into
+the arm,associativity nodes. The first integer is the most significant
+NUMA boundary and the following are progressively less significant boundaries.
+There can be more than one level of NUMA.
+
+Ex:
+	arm,associativity-reference-points = <0 1>;
+	The board Id(index 0) used first to calculate the associativity (node
+	distance), then follows the  socket id(index 1).
+
+	arm,associativity-reference-points = <1 0>;
+	The socket Id(index 1) used first to calculate the associativity,
+	then follows the board id(index 0).
+
+	arm,associativity-reference-points = <0>;
+	Only the board Id(index 0) used to calculate the associativity.
+
+	arm,associativity-reference-points = <1>;
+	Only socket Id(index 1) used to calculate the associativity.
+
+==============================================================================
+4 - Example dts
+==============================================================================
+
+Example: 2 Node system consists of 2 boards and each board having one socket
+and 8 core in each socket.
+
+	arm,associativity-reference-points = <0>;
+
+	memory at 00c00000 {
+		device_type = "memory";
+		reg = <0x0 0x00c00000 0x0 0x80000000>;
+		/* board 0, socket 0, no specific core */
+		arm,associativity = <0 0 0xffff>;
+	};
+
+	memory at 10000000000 {
+		device_type = "memory";
+		reg = <0x100 0x00000000 0x0 0x80000000>;
+		/* board 1, socket 0, no specific core */
+		arm,associativity = <1 0 0xffff>;
+	};
+
+	cpus {
+		#address-cells = <2>;
+		#size-cells = <0>;
+
+		cpu at 000 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x000>;
+			enable-method = "psci";
+			/* board 0, socket 0, core 0*/
+			arm,associativity = <0 0 0>;
+		};
+		cpu at 001 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x001>;
+			enable-method = "psci";
+			arm,associativity = <0 0 1>;
+		};
+		cpu at 002 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x002>;
+			enable-method = "psci";
+			arm,associativity = <0 0 2>;
+		};
+		cpu at 003 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x003>;
+			enable-method = "psci";
+			arm,associativity = <0 0 3>;
+		};
+		cpu at 004 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x004>;
+			enable-method = "psci";
+			arm,associativity = <0 0 4>;
+		};
+		cpu at 005 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x005>;
+			enable-method = "psci";
+			arm,associativity = <0 0 5>;
+		};
+		cpu at 006 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x006>;
+			enable-method = "psci";
+			arm,associativity = <0 0 6>;
+		};
+		cpu at 007 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x007>;
+			enable-method = "psci";
+			arm,associativity = <0 0 7>;
+		};
+		cpu at 008 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x008>;
+			enable-method = "psci";
+			/* board 1, socket 0, core 0*/
+			arm,associativity = <1 0 0>;
+		};
+		cpu at 009 {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x009>;
+			enable-method = "psci";
+			arm,associativity = <1 0 1>;
+		};
+		cpu at 00a {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x00a>;
+			enable-method = "psci";
+			arm,associativity = <0 0 2>;
+		};
+		cpu at 00b {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x00b>;
+			enable-method = "psci";
+			arm,associativity = <1 0 3>;
+		};
+		cpu at 00c {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x00c>;
+			enable-method = "psci";
+			arm,associativity = <1 0 4>;
+		};
+		cpu at 00d {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x00d>;
+			enable-method = "psci";
+			arm,associativity = <1 0 5>;
+		};
+		cpu at 00e {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x00e>;
+			enable-method = "psci";
+			arm,associativity = <1 0 6>;
+		};
+		cpu at 00f {
+			device_type = "cpu";
+			compatible =  "arm,armv8";
+			reg = <0x0 0x00f>;
+			enable-method = "psci";
+			arm,associativity = <1 0 7>;
+		};
+	};
+
+	pcie0: pcie0 at 0x8480,00000000 {
+		compatible = "arm,armv8";
+		device_type = "pci";
+		bus-range = <0 255>;
+		#size-cells = <2>;
+		#address-cells = <3>;
+		reg = <0x8480 0x00000000 0 0x10000000>;  /* Configuration space */
+		ranges = <0x03000000 0x8010 0x00000000 0x8010 0x00000000 0x70 0x00000000>; /* mem ranges */
+		/* board 0, socket 0, pci bus 0*/
+		arm,associativity = <0 0 0>;
+        };
-- 
1.8.1.4