+++ /dev/null
-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.
--- /dev/null
+# 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>;
+ };
+ };
+ };
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