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Message-ID: <20210907160317.2ec5304a@xps13>
Date: Tue, 7 Sep 2021 16:03:17 +0200
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Roger Quadros <rogerq@...nel.org>
Cc: tony@...mide.com, robh+dt@...nel.org, grygorii.strashko@...com,
nm@...com, lokeshvutla@...com, nsekhar@...com,
krzysztof.kozlowski@...onical.com, devicetree@...r.kernel.org,
linux-mtd@...ts.infradead.org, linux-omap@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 5/8] dt-bindings: mtd: ti,gpmc-nand: Convert to yaml
Hi Roger,
rogerq@...nel.org wrote on Tue, 7 Sep 2021 14:32:23 +0300:
> Convert gpmc-nand.txt to ti,gpmc-nand.yaml.
>
> Signed-off-by: Roger Quadros <rogerq@...nel.org>
> ---
> .../devicetree/bindings/mtd/gpmc-nand.txt | 147 ------------------
> .../devicetree/bindings/mtd/ti,gpmc-nand.yaml | 110 +++++++++++++
> 2 files changed, 110 insertions(+), 147 deletions(-)
> delete mode 100644 Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> create mode 100644 Documentation/devicetree/bindings/mtd/ti,gpmc-nand.yaml
>
> diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> deleted file mode 100644
> index 44919d48d241..000000000000
> --- a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
> +++ /dev/null
> @@ -1,147 +0,0 @@
> -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@...00000 {
> - 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.
> diff --git a/Documentation/devicetree/bindings/mtd/ti,gpmc-nand.yaml b/Documentation/devicetree/bindings/mtd/ti,gpmc-nand.yaml
> new file mode 100644
> index 000000000000..db36f2e944ef
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mtd/ti,gpmc-nand.yaml
> @@ -0,0 +1,110 @@
> +# 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@...mide.com>
> + - Roger Quadros <rogerq@...nel.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":
> + const: 1
> +
> + "#size-cells":
> + const: 1
> +
> + 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
Should perhaps keep the elm-id property documented but set to
'deprecated'.
> +
> + nand-bus-width:
> + description:
> + Bus width to the NAND chip
> + $ref: /schemas/types.yaml#/definitions/uint32
> + enum: [8, 16]
> + default: 8
This is part of nand-controller.yaml binding and should not be there.
> +
> +allOf:
> + - $ref: "../memory-controllers/ti,gpmc-child.yaml"
Maybe you need to reference the nand controller bindings as well
> +
> +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@...00000 {
> + 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>;
> + };
> + };
Thanks,
Miquèl
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