Commit a82d2069 authored by Miquel Raynal's avatar Miquel Raynal Committed by Boris Brezillon

dt-bindings: mtd: add Marvell NAND controller documentation

Document the legacy and the new bindings for Marvell NAND controller.

The pxa3xx_nand.c driver does only support legacy bindings, which are
incomplete and inaccurate. A rework of this controller (called
marvell_nand.c) does support both.
Signed-off-by: default avatarMiquel Raynal <miquel.raynal@free-electrons.com>
Reviewed-by: default avatarRob Herring <robh@kernel.org>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
parent b76bb4e6
Marvell NAND Flash Controller (NFC)
Required properties:
- compatible: can be one of the following:
* "marvell,armada-8k-nand-controller"
* "marvell,armada370-nand-controller"
* "marvell,pxa3xx-nand-controller"
* "marvell,armada-8k-nand" (deprecated)
* "marvell,armada370-nand" (deprecated)
* "marvell,pxa3xx-nand" (deprecated)
Compatibles marked deprecated support only the old bindings described
at the bottom.
- reg: NAND flash controller memory area.
- #address-cells: shall be set to 1. Encode the NAND CS.
- #size-cells: shall be set to 0.
- interrupts: shall define the NAND controller interrupt.
- clocks: shall reference the NAND controller clock.
- marvell,system-controller: Set to retrieve the syscon node that handles
NAND controller related registers (only required with the
"marvell,armada-8k-nand[-controller]" compatibles).
Optional properties:
- label: see partition.txt. New platforms shall omit this property.
- dmas: shall reference DMA channel associated to the NAND controller.
This property is only used with "marvell,pxa3xx-nand[-controller]"
compatible strings.
- dma-names: shall be "rxtx".
This property is only used with "marvell,pxa3xx-nand[-controller]"
compatible strings.
Optional children nodes:
Children nodes represent the available NAND chips.
Required properties:
- reg: shall contain the native Chip Select ids (0-3).
- nand-rb: see nand.txt (0-1).
Optional properties:
- marvell,nand-keep-config: orders the driver not to take the timings
from the core and leaving them completely untouched. Bootloader
timings will then be used.
- label: MTD name.
- nand-on-flash-bbt: see nand.txt.
- nand-ecc-mode: see nand.txt. Will use hardware ECC if not specified.
- nand-ecc-algo: see nand.txt. This property is essentially useful when
not using hardware ECC. Howerver, it may be added when using hardware
ECC for clarification but will be ignored by the driver because ECC
mode is chosen depending on the page size and the strength required by
the NAND chip. This value may be overwritten with nand-ecc-strength
property.
- nand-ecc-strength: see nand.txt.
- nand-ecc-step-size: see nand.txt. Marvell's NAND flash controller does
use fixed strength (1-bit for Hamming, 16-bit for BCH), so the actual
step size will shrink or grow in order to fit the required strength.
Step sizes are not completely random for all and follow certain
patterns described in AN-379, "Marvell SoC NFC ECC".
See Documentation/devicetree/bindings/mtd/nand.txt for more details on
generic bindings.
Example:
nand_controller: nand-controller@d0000 {
compatible = "marvell,armada370-nand-controller";
reg = <0xd0000 0x54>;
#address-cells = <1>;
#size-cells = <0>;
interrupts = <GIC_SPI 84 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&coredivclk 0>;
nand@0 {
reg = <0>;
label = "main-storage";
nand-rb = <0>;
nand-ecc-mode = "hw";
marvell,nand-keep-config;
nand-on-flash-bbt;
nand-ecc-strength = <4>;
nand-ecc-step-size = <512>;
partitions {
compatible = "fixed-partitions";
#address-cells = <1>;
#size-cells = <1>;
partition@0 {
label = "Rootfs";
reg = <0x00000000 0x40000000>;
};
};
};
};
Note on legacy bindings: One can find, in not-updated device trees,
bindings slightly different than described above with other properties
described below as well as the partitions node at the root of a so
called "nand" node (without clear controller/chip separation).
Legacy properties:
- marvell,nand-enable-arbiter: To enable the arbiter, all boards blindly
used it, this bit was set by the bootloader for many boards and even if
it is marked reserved in several datasheets, it might be needed to set
it (otherwise it is harmless) so whether or not this property is set,
the bit is selected by the driver.
- num-cs: Number of chip-select lines to use, all boards blindly set 1
to this and for a reason, other values would have failed. The value of
this property is ignored.
Example:
nand0: nand@43100000 {
compatible = "marvell,pxa3xx-nand";
reg = <0x43100000 90>;
interrupts = <45>;
dmas = <&pdma 97 0>;
dma-names = "rxtx";
#address-cells = <1>;
marvell,nand-keep-config;
marvell,nand-enable-arbiter;
num-cs = <1>;
/* Partitions (optional) */
};
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