firmware: Add coreboot device tree binding documentation (88cfb1ee) · Commits · 戴 / test

This patch adds documentation describing a device tree binding for the coreboot firmware. It is meant to be dynamically added during boot and contains address definitions for the coreboot table (a list of variable-sized descriptors providing information about various compile- and run-time generated firmware parameters) and the CBMEM area (the structure containing most run-time resident memory regions set up by coreboot). These definitions allow kernel drivers to easily access data contained in and pointed to by these regions (such as coreboot's in-memory log). (An example implementation can be seen in the following patch) Signed-off-by:

Julius Werner <jwerner@chromium.org> Signed-off-by:

Thierry Escande <thierry.escande@collabora.com> Acked-by:

Rob Herring <robh@kernel.org> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/firmware/coreboot.txt

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+33 −0

Original line number	Diff line number	Diff line
		COREBOOT firmware information

		The device tree node to communicate the location of coreboot's memory-resident
		bookkeeping structures to the kernel. Since coreboot itself cannot boot a
		device-tree-based kernel (yet), this node needs to be inserted by a
		second-stage bootloader (a coreboot "payload").

		Required properties:
		- compatible: Should be "coreboot"
		- reg: Address and length of the following two memory regions, in order:
		1.) The coreboot table. This is a list of variable-sized descriptors
		that contain various compile- and run-time generated firmware
		parameters. It is identified by the magic string "LBIO" in its first
		four bytes.
		See coreboot's src/commonlib/include/commonlib/coreboot_tables.h for
		details.
		2.) The CBMEM area. This is a downward-growing memory region used by
		coreboot to dynamically allocate data structures that remain resident.
		It may or may not include the coreboot table as one of its members. It
		is identified by a root node descriptor with the magic number
		0xc0389481 that resides in the topmost 8 bytes of the area.
		See coreboot's src/include/imd.h for details.

		Example:
		firmware {
		ranges;

		coreboot {
		compatible = "coreboot";
		reg = <0xfdfea000 0x264>,
		<0xfdfea000 0x16000>;
		}
		};

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