| * 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 */ |
| }; |
| }; |