xref: /kernel/linux/linux-6.6/Documentation/devicetree/bindings/mips/cavium/bootbus.txt

* Boot Bus

The Octeon Boot Bus is a configurable parallel bus with 8 chip
selects.  Each chip select is independently configurable.

Properties:
- compatible: "cavium,octeon-3860-bootbus"

  Compatibility with all cn3XXX, cn5XXX and cn6XXX SOCs.

- reg: The base address of the Boot Bus' register bank.

- #address-cells: Must be <2>.  The first cell is the chip select
   within the bootbus.  The second cell is the offset from the chip select.

- #size-cells: Must be <1>.

- ranges: There must be one one triplet of (child-bus-address,
  parent-bus-address, length) for each active chip select.  If the
  length element for any triplet is zero, the chip select is disabled,
  making it inactive.

The configuration parameters for each chip select are stored in child
nodes.

Configuration Properties:
- compatible:  "cavium,octeon-3860-bootbus-config"

- cavium,cs-index: A single cell indicating the chip select that
  corresponds to this configuration.

- cavium,t-adr: A cell specifying the ADR timing (in nS).

- cavium,t-ce: A cell specifying the CE timing (in nS).

- cavium,t-oe: A cell specifying the OE timing (in nS).

- cavium,t-we: A cell specifying the WE timing (in nS).

- cavium,t-rd-hld: A cell specifying the RD_HLD timing (in nS).

- cavium,t-wr-hld: A cell specifying the WR_HLD timing (in nS).

- cavium,t-pause: A cell specifying the PAUSE timing (in nS).

- cavium,t-wait: A cell specifying the WAIT timing (in nS).

- cavium,t-page: A cell specifying the PAGE timing (in nS).

- cavium,t-rd-dly: A cell specifying the RD_DLY timing (in nS).

- cavium,pages: A cell specifying the PAGES parameter (0 = 8 bytes, 1
  = 2 bytes, 2 = 4 bytes, 3 = 8 bytes).

- cavium,wait-mode: Optional.  If present, wait mode (WAITM) is selected.

- cavium,page-mode: Optional.  If present, page mode (PAGEM) is selected.

- cavium,bus-width: A cell specifying the WIDTH parameter (in bits) of
  the bus for this chip select.

- cavium,ale-mode: Optional.  If present, ALE mode is selected.

- cavium,sam-mode: Optional.  If present, SAM mode is selected.

- cavium,or-mode: Optional.  If present, OR mode is selected.

Example:
	bootbus: bootbus@1180000000000 {
		compatible = "cavium,octeon-3860-bootbus";
		reg = <0x11800 0x00000000 0x0 0x200>;
		/* The chip select number and offset */
		#address-cells = <2>;
		/* The size of the chip select region */
		#size-cells = <1>;
		ranges = <0 0  0x0 0x1f400000  0xc00000>,
			 <1 0  0x10000 0x30000000  0>,
			 <2 0  0x10000 0x40000000  0>,
			 <3 0  0x10000 0x50000000  0>,
			 <4 0  0x0 0x1d020000  0x10000>,
			 <5 0  0x0 0x1d040000  0x10000>,
			 <6 0  0x0 0x1d050000  0x10000>,
			 <7 0  0x10000 0x90000000  0>;

			cavium,cs-config@0 {
			compatible = "cavium,octeon-3860-bootbus-config";
			cavium,cs-index = <0>;
			cavium,t-adr  = <20>;
			cavium,t-ce   = <60>;
			cavium,t-oe   = <60>;
			cavium,t-we   = <45>;
			cavium,t-rd-hld = <35>;
			cavium,t-wr-hld = <45>;
			cavium,t-pause  = <0>;
			cavium,t-wait   = <0>;
			cavium,t-page   = <35>;
			cavium,t-rd-dly = <0>;

			cavium,pages     = <0>;
			cavium,bus-width = <8>;
		};
		.
		.
		.
		cavium,cs-config@6 {
			compatible = "cavium,octeon-3860-bootbus-config";
			cavium,cs-index = <6>;
			cavium,t-adr  = <5>;
			cavium,t-ce   = <300>;
			cavium,t-oe   = <270>;
			cavium,t-we   = <150>;
			cavium,t-rd-hld = <100>;
			cavium,t-wr-hld = <70>;
			cavium,t-pause  = <0>;
			cavium,t-wait   = <0>;
			cavium,t-page   = <320>;
			cavium,t-rd-dly = <0>;

			cavium,pages     = <0>;
			cavium,wait-mode;
			cavium,bus-width = <16>;
		};
		.
		.
		.
	};