dt-bindings: mtd: ti,gpmc-nand: Convert to yaml

Convert gpmc-nand.txt to ti,gpmc-nand.yaml.
Signed-off-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>

Documentation/devicetree/bindings/mtd/gpmc-nand.txt

-Device tree bindings for GPMC connected NANDs
-
-GPMC connected NAND (found on OMAP boards) are represented as child nodes of
-the GPMC controller with a name of "nand".
-
-All timing relevant properties as well as generic gpmc child properties are
-explained in a separate documents - please refer to
-Documentation/devicetree/bindings/memory-controllers/omap-gpmc.txt
-
-For NAND specific properties such as ECC modes or bus width, please refer to
-Documentation/devicetree/bindings/mtd/nand-controller.yaml
-
-
-Required properties:
-
- - compatible:	"ti,omap2-nand"
- - reg:		range id (CS number), base offset and length of the
-		NAND I/O space
- - interrupts:	Two interrupt specifiers, one for fifoevent, one for termcount.
-
-Optional properties:
-
- - nand-bus-width: 		Set this numeric value to 16 if the hardware
-				is wired that way. If not specified, a bus
-				width of 8 is assumed.
-
- - ti,nand-ecc-opt:		A string setting the ECC layout to use. One of:
-		"sw"		1-bit Hamming ecc code via software
-		"hw"		<deprecated> use "ham1" instead
-		"hw-romcode"	<deprecated> use "ham1" instead
-		"ham1"		1-bit Hamming ecc code
-		"bch4"		4-bit BCH ecc code
-		"bch8"		8-bit BCH ecc code
-		"bch16"		16-bit BCH ECC code
-		Refer below "How to select correct ECC scheme for your device ?"
-
- - ti,nand-xfer-type:		A string setting the data transfer type. One of:
-
-		"prefetch-polled"	Prefetch polled mode (default)
-		"polled"		Polled mode, without prefetch
-		"prefetch-dma"		Prefetch enabled DMA mode
-		"prefetch-irq"		Prefetch enabled irq mode
-
- - elm_id:	<deprecated> use "ti,elm-id" instead
- - ti,elm-id:	Specifies phandle of the ELM devicetree node.
-		ELM is an on-chip hardware engine on TI SoC which is used for
-		locating ECC errors for BCHx algorithms. SoC devices which have
-		ELM hardware engines should specify this device node in .dtsi
-		Using ELM for ECC error correction frees some CPU cycles.
- - rb-gpios:	GPIO specifier for the ready/busy# pin.
-
-For inline partition table parsing (optional):
-
- - #address-cells: should be set to 1
- - #size-cells: should be set to 1
-
-Example for an AM33xx board:
-
-	gpmc: gpmc@50000000 {
-		compatible = "ti,am3352-gpmc";
-		ti,hwmods = "gpmc";
-		reg = <0x50000000 0x36c>;
-		interrupts = <100>;
-		gpmc,num-cs = <8>;
-		gpmc,num-waitpins = <2>;
-		#address-cells = <2>;
-		#size-cells = <1>;
-		ranges = <0 0 0x08000000 0x1000000>;	/* CS0 space, 16MB */
-		elm_id = <&elm>;
-		interrupt-controller;
-		#interrupt-cells = <2>;
-
-		nand@0,0 {
-			compatible = "ti,omap2-nand";
-			reg = <0 0 4>;		/* CS0, offset 0, NAND I/O window 4 */
-			interrupt-parent = <&gpmc>;
-			interrupts = <0 IRQ_TYPE_NONE>, <1 IRQ_TYPE NONE>;
-			nand-bus-width = <16>;
-			ti,nand-ecc-opt = "bch8";
-			ti,nand-xfer-type = "polled";
-			rb-gpios = <&gpmc 0 GPIO_ACTIVE_HIGH>; /* gpmc_wait0 */
-
-			gpmc,sync-clk-ps = <0>;
-			gpmc,cs-on-ns = <0>;
-			gpmc,cs-rd-off-ns = <44>;
-			gpmc,cs-wr-off-ns = <44>;
-			gpmc,adv-on-ns = <6>;
-			gpmc,adv-rd-off-ns = <34>;
-			gpmc,adv-wr-off-ns = <44>;
-			gpmc,we-off-ns = <40>;
-			gpmc,oe-off-ns = <54>;
-			gpmc,access-ns = <64>;
-			gpmc,rd-cycle-ns = <82>;
-			gpmc,wr-cycle-ns = <82>;
-			gpmc,wr-access-ns = <40>;
-			gpmc,wr-data-mux-bus-ns = <0>;
-
-			#address-cells = <1>;
-			#size-cells = <1>;
-
-			/* partitions go here */
-		};
-	};
-
-How to select correct ECC scheme for your device ?
---------------------------------------------------
-Higher ECC scheme usually means better protection against bit-flips and
-increased system lifetime. However, selection of ECC scheme is dependent
-on various other factors also like;
-
-(1) support of built in hardware engines.
-	Some legacy OMAP SoC do not have ELM harware engine, so those SoC cannot
-	support ecc-schemes with hardware error-correction (BCHx_HW). However
-	such SoC can use ecc-schemes with software library for error-correction
-	(BCHx_HW_DETECTION_SW). The error correction capability with software
-	library remains equivalent to their hardware counter-part, but there is
-	slight CPU penalty when too many bit-flips are detected during reads.
-
-(2) Device parameters like OOBSIZE.
-	Other factor which governs the selection of ecc-scheme is oob-size.
-	Higher ECC schemes require more OOB/Spare area to store ECC syndrome,
-	so the device should have enough free bytes available its OOB/Spare
-	area to accommodate ECC for entire page. In general following expression
-	helps in determining if given device can accommodate ECC syndrome:
-	"2 + (PAGESIZE / 512) * ECC_BYTES" <= OOBSIZE"
-	where
-		OOBSIZE		number of bytes in OOB/spare area
-		PAGESIZE	number of bytes in main-area of device page
-		ECC_BYTES	number of ECC bytes generated to protect
-		                512 bytes of data, which is:
-				'3' for HAM1_xx ecc schemes
-				'7' for BCH4_xx ecc schemes
-				'14' for BCH8_xx ecc schemes
-				'26' for BCH16_xx ecc schemes
-
-	Example(a): For a device with PAGESIZE = 2048 and OOBSIZE = 64 and
-		trying to use BCH16 (ECC_BYTES=26) ecc-scheme.
-		Number of ECC bytes per page = (2 + (2048 / 512) * 26) = 106 B
-		which is greater than capacity of NAND device (OOBSIZE=64)
-		Hence, BCH16 cannot be supported on given device. But it can
-		probably use lower ecc-schemes like BCH8.
-
-	Example(b): For a device with PAGESIZE = 2048 and OOBSIZE = 128 and
-		trying to use BCH16 (ECC_BYTES=26) ecc-scheme.
-		Number of ECC bytes per page = (2 + (2048 / 512) * 26) = 106 B
-		which can be accommodated in the OOB/Spare area of this device
-		(OOBSIZE=128). So this device can use BCH16 ecc-scheme.

Documentation/devicetree/bindings/mtd/ti,gpmc-nand.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mtd/ti,gpmc-nand.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments GPMC NAND Flash controller.
+
+maintainers:
+  - Tony Lindgren <tony@atomide.com>
+  - Roger Quadros <rogerq@kernel.org>
+
+description:
+  GPMC NAND controller/Flash is represented as a child of the
+  GPMC controller node.
+
+properties:
+  compatible:
+    const: ti,omap2-nand
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    items:
+      - description: Interrupt for fifoevent
+      - description: Interrupt for termcount
+
+  "#address-cells": true
+
+  "#size-cells": true
+
+  ti,nand-ecc-opt:
+    description: Desired ECC algorithm
+    $ref: /schemas/types.yaml#/definitions/string
+    enum: [sw, ham1, bch4, bch8, bch16]
+
+  ti,nand-xfer-type:
+    description: Data transfer method between controller and chip.
+    $ref: /schemas/types.yaml#/definitions/string
+    enum: [prefetch-polled, polled, prefetch-dma, prefetch-irq]
+    default: prefetch-polled
+
+  ti,elm-id:
+    description:
+      phandle to the ELM (Error Location Module).
+    $ref: /schemas/types.yaml#/definitions/phandle
+
+  nand-bus-width:
+    description:
+      Bus width to the NAND chip
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [8, 16]
+    default: 8
+
+patternProperties:
+  "@[0-9a-f]+$":
+    $ref: "/schemas/mtd/partitions/partition.yaml"
+
+allOf:
+  - $ref: "/schemas/memory-controllers/ti,gpmc-child.yaml"
+
+required:
+  - compatible
+  - reg
+  - ti,nand-ecc-opt
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/gpio/gpio.h>
+
+    gpmc: memory-controller@50000000 {
+      compatible = "ti,am3352-gpmc";
+      dmas = <&edma 52 0>;
+      dma-names = "rxtx";
+      clocks = <&l3s_gclk>;
+      clock-names = "fck";
+      reg = <0x50000000 0x2000>;
+      interrupts = <GIC_SPI 100 IRQ_TYPE_LEVEL_HIGH>;
+      gpmc,num-cs = <7>;
+      gpmc,num-waitpins = <2>;
+      #address-cells = <2>;
+      #size-cells = <1>;
+      interrupt-controller;
+      #interrupt-cells = <2>;
+      gpio-controller;
+      #gpio-cells = <2>;
+
+      ranges = <0 0 0x08000000 0x01000000>;   /* CS0 space. Min partition = 16MB */
+      nand@0,0 {
+        compatible = "ti,omap2-nand";
+        reg = <0 0 4>;          /* device IO registers */
+        interrupt-parent = <&gpmc>;
+        interrupts = <0 IRQ_TYPE_NONE>, /* fifoevent */
+                     <1 IRQ_TYPE_NONE>; /* termcount */
+        ti,nand-xfer-type = "prefetch-dma";
+        ti,nand-ecc-opt = "bch16";
+        ti,elm-id = <&elm>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        /* NAND generic properties */
+        nand-bus-width = <8>;
+        rb-gpios = <&gpmc 0 GPIO_ACTIVE_HIGH>;  /* gpmc_wait0 */
+
+        /* GPMC properties*/
+        gpmc,device-width = <1>;
+
+        partition@0 {
+          label = "NAND.SPL";
+          reg = <0x00000000 0x00040000>;
+        };
+        partition@1 {
+          label = "NAND.SPL.backup1";
+          reg = <0x00040000 0x00040000>;
+        };
+      };
+    };