Thread (1 message) 1 message, 1 author, 2017-12-19
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[PATCH v2 1/5] dt-bindings: mtd: add Marvell NAND controller documentation

From: Miquel Raynal <hidden>
Date: 2017-12-19 13:29:38
Also in: linux-devicetree
Subsystem: memory technology devices (mtd), open firmware and flattened device tree bindings, the rest · Maintainers: Miquel Raynal, Richard Weinberger, Vignesh Raghavendra, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Linus Torvalds

Possibly related (same subject, not in this thread)

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 <redacted>
---
 .../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..aa6a1ed045b2
--- /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)
+- marvell,rb: shall contain the native Ready/Busy ids (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 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. This has no effect and will be
+  ignored by the driver when using hardware ECC because Marvell's NAND
+  flash controller does use fixed strength (1-bit for Hamming, 16-bit
+  for BCH), so the 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 at 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 at 0 {
+		reg = <0>;
+		label = "main-storage";
+		marvell,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 at 0 {
+				label = "Rootfs";
+				reg = <0x00000000 0x40000000>;
+			};
+		};
+	};
+};
+
+
+Note on legacy bindings: One can find, in not-updated device trees,
+bindings slightly differents 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 at 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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