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: Miquel Raynal <miquel.raynal@xxxxxxxxxxxxxxxxxx>
---
.../devicetree/bindings/mtd/marvell-nand.txt | 123 +++++++++++++++++++++
1 file changed, 123 insertions(+)
create mode 100644 Documentation/devicetree/bindings/mtd/marvell-nand.txt
diff --git a/Documentation/devicetree/bindings/mtd/marvell-nand.txt b/Documentation/devicetree/bindings/mtd/marvell-nand.txt
new file mode 100644
index 000000000000..c08fb477b3c6
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/marvell-nand.txt
@@ -0,0 +1,123 @@
+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) */
+ };
--
2.11.0
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