1# SPDX-License-Identifier: GPL-2.0 2%YAML 1.2 3--- 4$id: http://devicetree.org/schemas/mtd/nand-controller.yaml# 5$schema: http://devicetree.org/meta-schemas/core.yaml# 6 7title: NAND Chip and NAND Controller Generic Binding 8 9maintainers: 10 - Miquel Raynal <miquel.raynal@bootlin.com> 11 - Richard Weinberger <richard@nod.at> 12 13description: | 14 The NAND controller should be represented with its own DT node, and 15 all NAND chips attached to this controller should be defined as 16 children nodes of the NAND controller. This representation should be 17 enforced even for simple controllers supporting only one chip. 18 19 The ECC strength and ECC step size properties define the user 20 desires in terms of correction capability of a controller. Together, 21 they request the ECC engine to correct {strength} bit errors per 22 {size} bytes. 23 24 The interpretation of these parameters is implementation-defined, so 25 not all implementations must support all possible 26 combinations. However, implementations are encouraged to further 27 specify the value(s) they support. 28 29properties: 30 $nodename: 31 pattern: "^nand-controller(@.*)?" 32 33 "#address-cells": 34 const: 1 35 36 "#size-cells": 37 const: 0 38 39 ranges: true 40 41patternProperties: 42 "^nand@[a-f0-9]$": 43 properties: 44 reg: 45 description: 46 Contains the native Ready/Busy IDs. 47 48 nand-ecc-mode: 49 allOf: 50 - $ref: /schemas/types.yaml#/definitions/string 51 - enum: [ none, soft, hw, hw_syndrome, hw_oob_first, on-die ] 52 description: 53 Desired ECC engine, either hardware (most of the time 54 embedded in the NAND controller) or software correction 55 (Linux will handle the calculations). soft_bch is deprecated 56 and should be replaced by soft and nand-ecc-algo. 57 58 nand-ecc-algo: 59 allOf: 60 - $ref: /schemas/types.yaml#/definitions/string 61 - enum: [ hamming, bch, rs ] 62 description: 63 Desired ECC algorithm. 64 65 nand-bus-width: 66 allOf: 67 - $ref: /schemas/types.yaml#/definitions/uint32 68 - enum: [ 8, 16 ] 69 - default: 8 70 description: 71 Bus width to the NAND chip 72 73 nand-on-flash-bbt: 74 $ref: /schemas/types.yaml#/definitions/flag 75 description: 76 With this property, the OS will search the device for a Bad 77 Block Table (BBT). If not found, it will create one, reserve 78 a few blocks at the end of the device to store it and update 79 it as the device ages. Otherwise, the out-of-band area of a 80 few pages of all the blocks will be scanned at boot time to 81 find Bad Block Markers (BBM). These markers will help to 82 build a volatile BBT in RAM. 83 84 nand-ecc-strength: 85 allOf: 86 - $ref: /schemas/types.yaml#/definitions/uint32 87 - minimum: 1 88 description: 89 Maximum number of bits that can be corrected per ECC step. 90 91 nand-ecc-step-size: 92 allOf: 93 - $ref: /schemas/types.yaml#/definitions/uint32 94 - minimum: 1 95 description: 96 Number of data bytes covered by a single ECC step. 97 98 nand-ecc-maximize: 99 $ref: /schemas/types.yaml#/definitions/flag 100 description: 101 Whether or not the ECC strength should be maximized. The 102 maximum ECC strength is both controller and chip 103 dependent. The ECC engine has to select the ECC config 104 providing the best strength and taking the OOB area size 105 constraint into account. This is particularly useful when 106 only the in-band area is used by the upper layers, and you 107 want to make your NAND as reliable as possible. 108 109 nand-is-boot-medium: 110 $ref: /schemas/types.yaml#/definitions/flag 111 description: 112 Whether or not the NAND chip is a boot medium. Drivers might 113 use this information to select ECC algorithms supported by 114 the boot ROM or similar restrictions. 115 116 nand-rb: 117 $ref: /schemas/types.yaml#/definitions/uint32-array 118 description: 119 Contains the native Ready/Busy IDs. 120 121 required: 122 - reg 123 124required: 125 - "#address-cells" 126 - "#size-cells" 127 128examples: 129 - | 130 nand-controller { 131 #address-cells = <1>; 132 #size-cells = <0>; 133 134 /* controller specific properties */ 135 136 nand@0 { 137 reg = <0>; 138 nand-ecc-mode = "soft"; 139 nand-ecc-algo = "bch"; 140 141 /* controller specific properties */ 142 }; 143 }; 144