xref: /kernel/linux/linux-5.10/Documentation/devicetree/bindings/arm/cci.txt

=======================================================
ARM CCI cache coherent interconnect binding description
=======================================================

ARM multi-cluster systems maintain intra-cluster coherency through a
cache coherent interconnect (CCI) that is capable of monitoring bus
transactions and manage coherency, TLB invalidations and memory barriers.

It allows snooping and distributed virtual memory message broadcast across
clusters, through memory mapped interface, with a global control register
space and multiple sets of interface control registers, one per slave
interface.

* CCI interconnect node

	Description: Describes a CCI cache coherent Interconnect component

	Node name must be "cci".
	Node's parent must be the root node /, and the address space visible
	through the CCI interconnect is the same as the one seen from the
	root node (ie from CPUs perspective as per DT standard).
	Every CCI node has to define the following properties:

	- compatible
		Usage: required
		Value type: <string>
		Definition: must contain one of the following:
			    "arm,cci-400"
			    "arm,cci-500"
			    "arm,cci-550"

	- reg
		Usage: required
		Value type: Integer cells. A register entry, expressed as a pair
			    of cells, containing base and size.
		Definition: A standard property. Specifies base physical
			    address of CCI control registers common to all
			    interfaces.

	- ranges:
		Usage: required
		Value type: Integer cells. An array of range entries, expressed
			    as a tuple of cells, containing child address,
			    parent address and the size of the region in the
			    child address space.
		Definition: A standard property. Follow rules in the Devicetree
			    Specification for hierarchical bus addressing. CCI
			    interfaces addresses refer to the parent node
			    addressing scheme to declare their register bases.

	CCI interconnect node can define the following child nodes:

	- CCI control interface nodes

		Node name must be "slave-if".
		Parent node must be CCI interconnect node.

		A CCI control interface node must contain the following
		properties:

		- compatible
			Usage: required
			Value type: <string>
			Definition: must be set to
				    "arm,cci-400-ctrl-if"

		- interface-type:
			Usage: required
			Value type: <string>
			Definition: must be set to one of {"ace", "ace-lite"}
				    depending on the interface type the node
				    represents.

		- reg:
			Usage: required
			Value type: Integer cells. A register entry, expressed
				    as a pair of cells, containing base and
				    size.
			Definition: the base address and size of the
				    corresponding interface programming
				    registers.

	- CCI PMU node

		Parent node must be CCI interconnect node.

		A CCI pmu node must contain the following properties:

		- compatible
			Usage: required
			Value type: <string>
			Definition: Must contain one of:
				 "arm,cci-400-pmu,r0"
				 "arm,cci-400-pmu,r1"
				 "arm,cci-400-pmu"  - DEPRECATED, permitted only where OS has
						      secure access to CCI registers
				 "arm,cci-500-pmu,r0"
				 "arm,cci-550-pmu,r0"
		- reg:
			Usage: required
			Value type: Integer cells. A register entry, expressed
				    as a pair of cells, containing base and
				    size.
			Definition: the base address and size of the
				    corresponding interface programming
				    registers.

		- interrupts:
			Usage: required
			Value type: Integer cells. Array of interrupt specifier
				    entries, as defined in
				    ../interrupt-controller/interrupts.txt.
			Definition: list of counter overflow interrupts, one per
				    counter. The interrupts must be specified
				    starting with the cycle counter overflow
				    interrupt, followed by counter0 overflow
				    interrupt, counter1 overflow interrupt,...
				    ,counterN overflow interrupt.

				    The CCI PMU has an interrupt signal for each
				    counter. The number of interrupts must be
				    equal to the number of counters.

* CCI interconnect bus masters

	Description: masters in the device tree connected to a CCI port
		     (inclusive of CPUs and their cpu nodes).

	A CCI interconnect bus master node must contain the following
	properties:

	- cci-control-port:
		Usage: required
		Value type: <phandle>
		Definition: a phandle containing the CCI control interface node
			    the master is connected to.

Example:

	cpus {
		#size-cells = <0>;
		#address-cells = <1>;

		CPU0: cpu@0 {
			device_type = "cpu";
			compatible = "arm,cortex-a15";
			cci-control-port = <&cci_control1>;
			reg = <0x0>;
		};

		CPU1: cpu@1 {
			device_type = "cpu";
			compatible = "arm,cortex-a15";
			cci-control-port = <&cci_control1>;
			reg = <0x1>;
		};

		CPU2: cpu@100 {
			device_type = "cpu";
			compatible = "arm,cortex-a7";
			cci-control-port = <&cci_control2>;
			reg = <0x100>;
		};

		CPU3: cpu@101 {
			device_type = "cpu";
			compatible = "arm,cortex-a7";
			cci-control-port = <&cci_control2>;
			reg = <0x101>;
		};

	};

	dma0: dma@3000000 {
		compatible = "arm,pl330", "arm,primecell";
		cci-control-port = <&cci_control0>;
		reg = <0x0 0x3000000 0x0 0x1000>;
		interrupts = <10>;
		#dma-cells = <1>;
		#dma-channels = <8>;
		#dma-requests = <32>;
	};

	cci@2c090000 {
		compatible = "arm,cci-400";
		#address-cells = <1>;
		#size-cells = <1>;
		reg = <0x0 0x2c090000 0 0x1000>;
		ranges = <0x0 0x0 0x2c090000 0x10000>;

		cci_control0: slave-if@1000 {
			compatible = "arm,cci-400-ctrl-if";
			interface-type = "ace-lite";
			reg = <0x1000 0x1000>;
		};

		cci_control1: slave-if@4000 {
			compatible = "arm,cci-400-ctrl-if";
			interface-type = "ace";
			reg = <0x4000 0x1000>;
		};

		cci_control2: slave-if@5000 {
			compatible = "arm,cci-400-ctrl-if";
			interface-type = "ace";
			reg = <0x5000 0x1000>;
		};

		pmu@9000 {
			 compatible = "arm,cci-400-pmu";
			 reg = <0x9000 0x5000>;
			 interrupts = <0 101 4>,
				      <0 102 4>,
				      <0 103 4>,
				      <0 104 4>,
				      <0 105 4>;
		};
	};

This CCI node corresponds to a CCI component whose control registers sits
at address 0x000000002c090000.
CCI slave interface @0x000000002c091000 is connected to dma controller dma0.
CCI slave interface @0x000000002c094000 is connected to CPUs {CPU0, CPU1};
CCI slave interface @0x000000002c095000 is connected to CPUs {CPU2, CPU3};