dt-bindings: mtd: Add YAML schemas for the generic NAND options

The NAND chips in MTD have a bunch of generic options that are needed in a
device tree. Add a YAML schemas for those.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
This commit is contained in:
Maxime Ripard 2019-04-03 09:48:04 +02:00 committed by Miquel Raynal
parent cf3bbe67be
commit 212e496935
2 changed files with 143 additions and 75 deletions

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# SPDX-License-Identifier: GPL-2.0
%YAML 1.2
---
$id: http://devicetree.org/schemas/mtd/nand-controller.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: NAND Chip and NAND Controller Generic Binding
maintainers:
- Miquel Raynal <miquel.raynal@bootlin.com>
- Richard Weinberger <richard@nod.at>
description: |
The NAND controller should be represented with its own DT node, and
all NAND chips attached to this controller should be defined as
children nodes of the NAND controller. This representation should be
enforced even for simple controllers supporting only one chip.
The ECC strength and ECC step size properties define the user
desires in terms of correction capability of a controller. Together,
they request the ECC engine to correct {strength} bit errors per
{size} bytes.
The interpretation of these parameters is implementation-defined, so
not all implementations must support all possible
combinations. However, implementations are encouraged to further
specify the value(s) they support.
properties:
$nodename:
pattern: "^nand-controller(@.*)?"
"#address-cells":
const: 1
"#size-cells":
const: 0
ranges: true
patternProperties:
"^nand@[a-f0-9]$":
properties:
reg:
description:
Contains the native Ready/Busy IDs.
nand-ecc-mode:
allOf:
- $ref: /schemas/types.yaml#/definitions/string
- enum: [ none, soft, hw, hw_syndrome, hw_oob_first, on-die ]
description:
Desired ECC engine, either hardware (most of the time
embedded in the NAND controller) or software correction
(Linux will handle the calculations). soft_bch is deprecated
and should be replaced by soft and nand-ecc-algo.
nand-ecc-algo:
allOf:
- $ref: /schemas/types.yaml#/definitions/string
- enum: [ hamming, bch, rs ]
description:
Desired ECC algorithm.
nand-bus-width:
allOf:
- $ref: /schemas/types.yaml#/definitions/uint32
- enum: [ 8, 16 ]
- default: 8
description:
Bus width to the NAND chip
nand-on-flash-bbt:
$ref: /schemas/types.yaml#/definitions/flag
description:
With this property, the OS will search the device for a Bad
Block Table (BBT). If not found, it will create one, reserve
a few blocks at the end of the device to store it and update
it as the device ages. Otherwise, the out-of-band area of a
few pages of all the blocks will be scanned at boot time to
find Bad Block Markers (BBM). These markers will help to
build a volatile BBT in RAM.
nand-ecc-strength:
allOf:
- $ref: /schemas/types.yaml#/definitions/uint32
- minimum: 1
description:
Maximum number of bits that can be corrected per ECC step.
nand-ecc-step-size:
allOf:
- $ref: /schemas/types.yaml#/definitions/uint32
- minimum: 1
description:
Number of data bytes covered by a single ECC step.
nand-ecc-maximize:
$ref: /schemas/types.yaml#/definitions/flag
description:
Whether or not the ECC strength should be maximized. The
maximum ECC strength is both controller and chip
dependent. The ECC engine has to select the ECC config
providing the best strength and taking the OOB area size
constraint into account. This is particularly useful when
only the in-band area is used by the upper layers, and you
want to make your NAND as reliable as possible.
nand-is-boot-medium:
$ref: /schemas/types.yaml#/definitions/flag
description:
Whether or not the NAND chip is a boot medium. Drivers might
use this information to select ECC algorithms supported by
the boot ROM or similar restrictions.
nand-rb:
$ref: /schemas/types.yaml#/definitions/uint32-array
description:
Contains the native Ready/Busy IDs.
required:
- reg
required:
- "#address-cells"
- "#size-cells"
examples:
- |
nand-controller {
#address-cells = <1>;
#size-cells = <0>;
/* controller specific properties */
nand@0 {
reg = <0>;
nand-ecc-mode = "soft";
nand-ecc-algo = "bch";
/* controller specific properties */
};
};

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* NAND chip and NAND controller generic binding
NAND controller/NAND chip representation:
The NAND controller should be represented with its own DT node, and all
NAND chips attached to this controller should be defined as children nodes
of the NAND controller. This representation should be enforced even for
simple controllers supporting only one chip.
Mandatory NAND controller properties:
- #address-cells: depends on your controller. Should at least be 1 to
encode the CS line id.
- #size-cells: depends on your controller. Put zero unless you need a
mapping between CS lines and dedicated memory regions
Optional NAND controller properties
- ranges: only needed if you need to define a mapping between CS lines and
memory regions
Optional NAND chip properties:
- nand-ecc-mode : String, operation mode of the NAND ecc mode.
Supported values are: "none", "soft", "hw", "hw_syndrome",
"hw_oob_first", "on-die".
Deprecated values:
"soft_bch": use "soft" and nand-ecc-algo instead
- nand-ecc-algo: string, algorithm of NAND ECC.
Valid values are: "hamming", "bch", "rs".
- nand-bus-width : 8 or 16 bus width if not present 8
- nand-on-flash-bbt: boolean to enable on flash bbt option if not present false
- nand-ecc-strength: integer representing the number of bits to correct
per ECC step.
- nand-ecc-step-size: integer representing the number of data bytes
that are covered by a single ECC step.
- nand-ecc-maximize: boolean used to specify that you want to maximize ECC
strength. The maximum ECC strength is both controller and
chip dependent. The controller side has to select the ECC
config providing the best strength and taking the OOB area
size constraint into account.
This is particularly useful when only the in-band area is
used by the upper layers, and you want to make your NAND
as reliable as possible.
- nand-is-boot-medium: Whether the NAND chip is a boot medium. Drivers might use
this information to select ECC algorithms supported by
the boot ROM or similar restrictions.
- nand-rb: shall contain the native Ready/Busy ids.
The ECC strength and ECC step size properties define the correction capability
of a controller. Together, they say a controller can correct "{strength} bit
errors per {size} bytes".
The interpretation of these parameters is implementation-defined, so not all
implementations must support all possible combinations. However, implementations
are encouraged to further specify the value(s) they support.
Example:
nand-controller {
#address-cells = <1>;
#size-cells = <0>;
/* controller specific properties */
nand@0 {
reg = <0>;
nand-ecc-mode = "soft";
nand-ecc-algo = "bch";
/* controller specific properties */
};
};