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Commit 1fdab21d authored by Boris Brezillon's avatar Boris Brezillon Committed by Alexandre Belloni
Browse files

memory: atmel-ebi: add DT bindings documentation 



The EBI (External Bus Interface) is used to access external peripherals
(NOR, SRAM, NAND, and other specific devices like ethernet controllers).
Each device is assigned a CS line and an address range and can have its
own configuration (timings, access mode, bus width, ...).
This driver provides a generic DT binding to configure a device according
to its requirements.
For specific device controllers (like the NAND one) the SMC timings
should be configured by the controller driver through the matrix and smc
syscon regmaps.

Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
parent 6a4ec4cd

Documentation/devicetree/bindings/memory-controllers/atmel,ebi.txt

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* Device tree bindings for Atmel EBI



The External Bus Interface (EBI) controller is a bus where you can connect

asynchronous (NAND, NOR, SRAM, ....) and synchronous memories (SDR/DDR SDRAMs).

The EBI provides a glue-less interface to asynchronous memories through the SMC

(Static Memory Controller).



Required properties:



- compatible:		"atmel,at91sam9260-ebi"

			"atmel,at91sam9261-ebi"

			"atmel,at91sam9263-ebi0"

			"atmel,at91sam9263-ebi1"

			"atmel,at91sam9rl-ebi"

			"atmel,at91sam9g45-ebi"

			"atmel,at91sam9x5-ebi"

			"atmel,sama5d3-ebi"



- reg:			Contains offset/length value for EBI memory mapping.

			This property might contain several entries if the EBI

			memory range is not contiguous



- #address-cells:	Must be 2.

			The first cell encodes the CS.

			The second cell encode the offset into the CS memory

			range.



- #size-cells:		Must be set to 1.



- ranges:		Encodes CS to memory region association.



- clocks:		Clock feeding the EBI controller.

			See clock-bindings.txt



Children device nodes are representing device connected to the EBI bus.



Required device node properties:



- reg:			Contains the chip-select id, the offset and the length

			of the memory region requested by the device.



EBI bus configuration will be defined directly in the device subnode.



Optional EBI/SMC properties:



- atmel,smc-bus-width:		width of the asynchronous device's data bus

				8, 16 or 32.

				Default to 8 when undefined.



- atmel,smc-byte-access-type	"write" or "select" (see Atmel datasheet).

				Default to "select" when undefined.



- atmel,smc-read-mode		"nrd" or "ncs".

				Default to "ncs" when undefined.



- atmel,smc-write-mode		"nwe" or "ncs".

				Default to "ncs" when undefined.



- atmel,smc-exnw-mode		"disabled", "frozen" or "ready".

				Default to "disabled" when undefined.



- atmel,smc-page-mode		enable page mode if present. The provided value

				defines the page size (supported values: 4, 8,

				16 and 32).



- atmel,smc-tdf-mode:		"normal" or "optimized". When set to

				"optimized" the data float time is optimized

				depending on the next device being accessed

				(next device setup time is subtracted to the

				current device data float time).

				Default to "normal" when undefined.



If at least one atmel,smc- property is defined the following SMC timing

properties become mandatory. In the other hand, if none of the atmel,smc-

properties are specified, we assume that the EBI bus configuration will be

handled by the sub-device driver, and none of those properties should be

defined.



All the timings are expressed in nanoseconds (see Atmel datasheet for a full

description).



- atmel,smc-ncs-rd-setup-ns

- atmel,smc-nrd-setup-ns

- atmel,smc-ncs-wr-setup-ns

- atmel,smc-nwe-setup-ns

- atmel,smc-ncs-rd-pulse-ns

- atmel,smc-nrd-pulse-ns

- atmel,smc-ncs-wr-pulse-ns

- atmel,smc-nwe-pulse-ns

- atmel,smc-nwe-cycle-ns

- atmel,smc-nrd-cycle-ns

- atmel,smc-tdf-ns



Example:



	ebi: ebi@10000000 {

		compatible = "atmel,sama5d3-ebi";

		#address-cells = <2>;

		#size-cells = <1>;

		atmel,smc = <&hsmc>;

		atmel,matrix = <&matrix>;

		reg = <0x10000000 0x10000000

		       0x40000000 0x30000000>;

		ranges = <0x0 0x0 0x10000000 0x10000000

			  0x1 0x0 0x40000000 0x10000000

			  0x2 0x0 0x50000000 0x10000000

			  0x3 0x0 0x60000000 0x10000000>;

		clocks = <&mck>;



		pinctrl-names = "default";

		pinctrl-0 = <&pinctrl_ebi_addr>;



		nor: flash@0,0 {

			compatible = "cfi-flash";

			#address-cells = <1>;

			#size-cells = <1>;

			reg = <0x0 0x0 0x1000000>;

			bank-width = <2>;



			atmel,smc-read-mode = "nrd";

			atmel,smc-write-mode = "nwe";

			atmel,smc-bus-width = <16>;

			atmel,smc-ncs-rd-setup-ns = <0>;

			atmel,smc-ncs-wr-setup-ns = <0>;

			atmel,smc-nwe-setup-ns = <8>;

			atmel,smc-nrd-setup-ns = <16>;

			atmel,smc-ncs-rd-pulse-ns = <84>;

			atmel,smc-ncs-wr-pulse-ns = <84>;

			atmel,smc-nrd-pulse-ns = <76>;

			atmel,smc-nwe-pulse-ns = <76>;

			atmel,smc-nrd-cycle-ns = <107>;

			atmel,smc-nwe-cycle-ns = <84>;

			atmel,smc-tdf-ns = <16>;

		};

	};