* CoreSight Components:

CoreSight components are compliant with the ARM CoreSight architecture
specification and can be connected in various topologies to suit a particular
SoCs tracing needs. These trace components can generally be classified as
sinks, links and sources. Trace data produced by one or more sources flows
through the intermediate links connecting the source to the currently selected
sink. Each CoreSight component device should use these properties to describe
its hardware characteristcs.

* Required properties for all components *except* non-configurable replicators
  and non-configurable funnels:

	* compatible: These have to be supplemented with "arm,primecell" as
	  drivers are using the AMBA bus interface.  Possible values include:
		- Embedded Trace Buffer (version 1.0):
			"arm,coresight-etb10", "arm,primecell";

		- Trace Port Interface Unit:
			"arm,coresight-tpiu", "arm,primecell";

		- Trace Memory Controller, used for Embedded Trace Buffer(ETB),
		  Embedded Trace FIFO(ETF) and Embedded Trace Router(ETR)
		  configuration.  The configuration mode (ETB, ETF, ETR) is
		  discovered at boot time when the device is probed.
			"arm,coresight-tmc", "arm,primecell";

		- Trace Programmable Funnel:
			"arm,coresight-dynamic-funnel", "arm,primecell";
			"arm,coresight-funnel", "arm,primecell"; (OBSOLETE. For
				backward compatibility and will be removed)

		- Embedded Trace Macrocell (version 3.x) and
					Program Flow Trace Macrocell:
			"arm,coresight-etm3x", "arm,primecell";

		- Embedded Trace Macrocell (version 4.x), with memory mapped access.
			"arm,coresight-etm4x", "arm,primecell";

		- Embedded Trace Macrocell (version 4.x), with system register access only.
			"arm,coresight-etm4x-sysreg";

		- Coresight programmable Replicator :
			"arm,coresight-dynamic-replicator", "arm,primecell";

		- System Trace Macrocell:
			"arm,coresight-stm", "arm,primecell"; [1]
		- Coresight Address Translation Unit (CATU)
			"arm,coresight-catu", "arm,primecell";

		- Coresight Cross Trigger Interface (CTI):
			"arm,coresight-cti", "arm,primecell";
			See coresight-cti.yaml for full CTI definitions.

	* reg: physical base address and length of the register
	  set(s) of the component.

	* clocks: the clocks associated to this component.

	* clock-names: the name of the clocks referenced by the code.
	  Since we are using the AMBA framework, the name of the clock
	  providing the interconnect should be "apb_pclk", and some
	  coresight blocks also have an additional clock "atclk", which
	  clocks the core of that coresight component. The latter clock
	  is optional.

	* port or ports: see "Graph bindings for Coresight" below.

* Additional required property for Embedded Trace Macrocell (version 3.x and
  version 4.x):
	* cpu: the cpu phandle this ETM/PTM is affined to. Do not
	  assume it to default to CPU0 if omitted.

* Additional required properties for System Trace Macrocells (STM):
	* reg: along with the physical base address and length of the register
	  set as described above, another entry is required to describe the
	  mapping of the extended stimulus port area.

	* reg-names: the only acceptable values are "stm-base" and
	  "stm-stimulus-base", each corresponding to the areas defined in "reg".

* Required properties for Coresight Cross Trigger Interface (CTI)
	See coresight-cti.yaml for full CTI definitions.

* Required properties for devices that don't show up on the AMBA bus, such as
  non-configurable replicators and non-configurable funnels:

	* compatible: Currently supported value is (note the absence of the
	  AMBA markee):
		- Coresight Non-configurable Replicator:
			"arm,coresight-static-replicator";
			"arm,coresight-replicator"; (OBSOLETE. For backward
				compatibility and will be removed)

		- Coresight Non-configurable Funnel:
			"arm,coresight-static-funnel";

	* port or ports: see "Graph bindings for Coresight" below.

* Optional properties for all components:

	* arm,coresight-loses-context-with-cpu : boolean. Indicates that the
	  hardware will lose register context on CPU power down (e.g. CPUIdle).
	  An example of where this may be needed are systems which contain a
	  coresight component and CPU in the same power domain. When the CPU
	  powers down the coresight component also powers down and loses its
	  context. This property is currently only used for the ETM 4.x driver.

* Optional properties for ETM/PTMs:

	* arm,cp14: must be present if the system accesses ETM/PTM management
	  registers via co-processor 14.

	* qcom,skip-power-up: boolean. Indicates that an implementation can
	  skip powering up the trace unit. TRCPDCR.PU does not have to be set
	  on Qualcomm Technologies Inc. systems since ETMs are in the same power
	  domain as their CPU cores. This property is required to identify such
	  systems with hardware errata where the CPU watchdog counter is stopped
	  when TRCPDCR.PU is set.

* Optional property for TMC:

	* arm,buffer-size: size of contiguous buffer space for TMC ETR
	  (embedded trace router). This property is obsolete. The buffer size
	  can be configured dynamically via buffer_size property in sysfs.

	* arm,scatter-gather: boolean. Indicates that the TMC-ETR can safely
	  use the SG mode on this system.

	* arm,max-burst-size: The maximum burst size initiated by TMC on the
	  AXI master interface. The burst size can be in the range [0..15],
	  the setting supports one data transfer per burst up to a maximum of
	  16 data transfers per burst.

* Optional property for CATU :
	* interrupts : Exactly one SPI may be listed for reporting the address
	  error

* Optional property for configurable replicators:

	* qcom,replicator-loses-context: boolean. Indicates that the replicator
	  will lose register context when AMBA clock is removed which is observed
	  in some replicator designs.

Graph bindings for Coresight
-------------------------------

Coresight components are interconnected to create a data path for the flow of
trace data generated from the "sources" to their collection points "sink".
Each coresight component must describe the "input" and "output" connections.
The connections must be described via generic DT graph bindings as described
by the "bindings/graph.txt", where each "port" along with an "endpoint"
component represents a hardware port and the connection.

 * All output ports must be listed inside a child node named "out-ports"
 * All input ports must be listed inside a child node named "in-ports".
 * Port address must match the hardware port number.

Example:

1. Sinks
	etb@20010000 {
		compatible = "arm,coresight-etb10", "arm,primecell";
		reg = <0 0x20010000 0 0x1000>;

		clocks = <&oscclk6a>;
		clock-names = "apb_pclk";
		in-ports {
			port {
				etb_in_port: endpoint@0 {
					remote-endpoint = <&replicator_out_port0>;
				};
			};
		};
	};

	tpiu@20030000 {
		compatible = "arm,coresight-tpiu", "arm,primecell";
		reg = <0 0x20030000 0 0x1000>;

		clocks = <&oscclk6a>;
		clock-names = "apb_pclk";
		in-ports {
			port {
				tpiu_in_port: endpoint@0 {
					remote-endpoint = <&replicator_out_port1>;
				};
			};
		};
	};

	etr@20070000 {
		compatible = "arm,coresight-tmc", "arm,primecell";
		reg = <0 0x20070000 0 0x1000>;

		clocks = <&oscclk6a>;
		clock-names = "apb_pclk";
		in-ports {
			port {
				etr_in_port: endpoint {
					remote-endpoint = <&replicator2_out_port0>;
				};
			};
		};

		out-ports {
			port {
				etr_out_port: endpoint {
					remote-endpoint = <&catu_in_port>;
				};
			};
		};
	};

2. Links
	replicator {
		/* non-configurable replicators don't show up on the
		 * AMBA bus.  As such no need to add "arm,primecell".
		 */
		compatible = "arm,coresight-static-replicator";

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

			/* replicator output ports */
			port@0 {
				reg = <0>;
				replicator_out_port0: endpoint {
					remote-endpoint = <&etb_in_port>;
				};
			};

			port@1 {
				reg = <1>;
				replicator_out_port1: endpoint {
					remote-endpoint = <&tpiu_in_port>;
				};
			};
		};

		in-ports {
			port {
				replicator_in_port0: endpoint {
					remote-endpoint = <&funnel_out_port0>;
				};
			};
		};
	};

	funnel {
		/*
		 * non-configurable funnel don't show up on the AMBA
		 * bus.  As such no need to add "arm,primecell".
		 */
		compatible = "arm,coresight-static-funnel";
		clocks = <&crg_ctrl HI3660_PCLK>;
		clock-names = "apb_pclk";

		out-ports {
			port {
				combo_funnel_out: endpoint {
					remote-endpoint = <&top_funnel_in>;
				};
			};
		};

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

			port@0 {
				reg = <0>;
				combo_funnel_in0: endpoint {
					remote-endpoint = <&cluster0_etf_out>;
				};
			};

			port@1 {
				reg = <1>;
				combo_funnel_in1: endpoint {
					remote-endpoint = <&cluster1_etf_out>;
				};
			};
		};
	};

	funnel@20040000 {
		compatible = "arm,coresight-dynamic-funnel", "arm,primecell";
		reg = <0 0x20040000 0 0x1000>;

		clocks = <&oscclk6a>;
		clock-names = "apb_pclk";
		out-ports {
			port {
				funnel_out_port0: endpoint {
					remote-endpoint =
							<&replicator_in_port0>;
				};
			};
		};

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

			port@0 {
				reg = <0>;
				funnel_in_port0: endpoint {
					remote-endpoint = <&ptm0_out_port>;
				};
			};

			port@1 {
				reg = <1>;
				funnel_in_port1: endpoint {
					remote-endpoint = <&ptm1_out_port>;
				};
			};

			port@2 {
				reg = <2>;
				funnel_in_port2: endpoint {
					remote-endpoint = <&etm0_out_port>;
				};
			};

		};
	};

3. Sources
	ptm@2201c000 {
		compatible = "arm,coresight-etm3x", "arm,primecell";
		reg = <0 0x2201c000 0 0x1000>;

		cpu = <&cpu0>;
		clocks = <&oscclk6a>;
		clock-names = "apb_pclk";
		out-ports {
			port {
				ptm0_out_port: endpoint {
					remote-endpoint = <&funnel_in_port0>;
				};
			};
		};
	};

	ptm@2201d000 {
		compatible = "arm,coresight-etm3x", "arm,primecell";
		reg = <0 0x2201d000 0 0x1000>;

		cpu = <&cpu1>;
		clocks = <&oscclk6a>;
		clock-names = "apb_pclk";
		out-ports {
			port {
				ptm1_out_port: endpoint {
					remote-endpoint = <&funnel_in_port1>;
				};
			};
		};
	};

4. STM
	stm@20100000 {
		compatible = "arm,coresight-stm", "arm,primecell";
		reg = <0 0x20100000 0 0x1000>,
		      <0 0x28000000 0 0x180000>;
		reg-names = "stm-base", "stm-stimulus-base";

		clocks = <&soc_smc50mhz>;
		clock-names = "apb_pclk";
		out-ports {
			port {
				stm_out_port: endpoint {
					remote-endpoint = <&main_funnel_in_port2>;
				};
			};
		};
	};

5. CATU

	catu@207e0000 {
		compatible = "arm,coresight-catu", "arm,primecell";
		reg = <0 0x207e0000 0 0x1000>;

		clocks = <&oscclk6a>;
		clock-names = "apb_pclk";

		interrupts = <GIC_SPI 4 IRQ_TYPE_LEVEL_HIGH>;
		in-ports {
			port {
				catu_in_port: endpoint {
					remote-endpoint = <&etr_out_port>;
				};
			};
		};
	};

[1]. There is currently two version of STM: STM32 and STM500.  Both
have the same HW interface and as such don't need an explicit binding name.