[PATCH 1/3] dt-bindings: mtd: stm32_fmc2: add STM32 FMC2 NAND controller documentation

[<christophe.kerello@st.com>]

From: Christophe Kerello <christophe.kerello@st.com>

This patch adds the documentation of the device tree bindings for the STM32
FMC2 NAND controller.

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
---
 .../devicetree/bindings/mtd/stm32-fmc2-nand.txt    | 90 ++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mtd/stm32-fmc2-nand.txt

diff --git a/Documentation/devicetree/bindings/mtd/stm32-fmc2-nand.txt b/Documentation/devicetree/bindings/mtd/stm32-fmc2-nand.txt
new file mode 100644
index 0000000..93eaf11
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/stm32-fmc2-nand.txt
@@ -0,0 +1,90 @@
+STMicroelectronics Flexible Memory Controller 2 (FMC2)
+NAND Interface
+
+Required properties:
+- compatible: "st,stm32mp15-fmc2"
+- reg: the first contains the register location and length
+       the second contains the data common space used for cs0 and length
+       the third contains the cmd attribute space used for cs0 and length
+       the fourth contains the addr attribute space used for cs0 and length
+       the fifth contains the data common space used for cs1 and length
+       the sixth contains the cmd attribute space used for cs1 and length
+       the seventh contains the addr attribute space used for cs1 and length
+- interrupts: The interrupt number
+- pinctrl-0: Standard Pinctrl phandle (see: pinctrl/pinctrl-bindings.txt)
+- clocks: Use common clock framework
+
+Optional properties:
+- resets: Reference to a reset controller asserting the FMC controller
+- dmas: DMA specifiers (see: dma/stm32-mdma.txt)
+- dma-names: Must be "tx", "rx" and "ecc"
+
+Optional children nodes:
+Children nodes represent the available nand chips.
+
+Optional properties:
+- nand-on-flash-bbt: see nand.txt
+- nand-ecc-strength: see nand.txt
+- nand-ecc-step-size: see nand.txt
+- st,fmc2_timings: array of 8 bytes for NAND timings. The meanings of
+  these bytes are:
+  byte 0 TCLR      : CLE to RE delay in number of AHB clock cycles, only 4 bits
+                     are valid. Zero means one clock cycle, 15 means 16 clock
+                     cycles.
+  byte 1 TAR       : ALE to RE delay, 4 bits are valid. Same format as TCLR.
+  byte 2 THIZ      : number of HCLK clock cycles during which the data bus is
+                     kept in Hi-Z (tristate) after the start of a write access.
+                     Only valid for write transactions. Zero means 1 cycle,
+                     255 means 256 cycles.
+  byte 3 TWAIT     : number of HCLK clock cycles to assert the command to the
+                     NAND flash in response to SMWAITn. Zero means 1 cycle,
+                     255 means 256 cycles.
+  byte 4 THOLD_MEM : common memory space timing
+                     number of HCLK clock cycles to hold the address (and data
+                     when writing) after the command deassertion. Zero means
+                     1 cycle, 255 means 256 cycles.
+  byte 5 TSET_MEM  : common memory space timing
+                     number of HCLK clock cycles to assert the address before
+                     the command is asserted. Zero means 1 cycle, 255 means 256
+                     cycles.
+  byte 6 THOLD_ATT : attribute memory space timing
+                     number of HCLK clock cycles to hold the address (and data
+                     when writing) after the command deassertion. Zero means
+                     1 cycle, 255 means 256 cycles.
+  byte 7 TSET_ATT  : attribute memory space timing
+                     number of HCLK clock cycles to assert the address before
+                     the command is asserted. Zero means 1 cycle, 255 means 256
+                     cycles.
+
+The following ECC strength and step size are currently supported:
+ - nand-ecc-strength = <1>, nand-ecc-step-size = <512> (HAMMING)
+ - nand-ecc-strength = <4>, nand-ecc-step-size = <512> (BCH4)
+ - nand-ecc-strength = <8>, nand-ecc-step-size = <512> (BCH8) (default)
+
+Example:
+
+	fmc2_nand: fmc2_nand@58002000 {
+		compatible = "st,stm32mp15-fmc2";
+		reg = <0x58002000 0x1000>,
+		      <0x80000000 0x1000>,
+		      <0x88010000 0x1000>,
+		      <0x88020000 0x1000>,
+		      <0x81000000 0x1000>,
+		      <0x89010000 0x1000>,
+		      <0x89020000 0x1000>;
+		interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&rcc FMC_K>;
+		resets = <&rcc FMC_R>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&fmc2_pins_a>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		nand@0 {
+			reg = <0>;
+			nand-on-flash-bbt;
+			st,fmc2_timings = /bits/ 8 <2 2 1 7 1 0 104 25>;
+			#address-cells = <1>;
+			#size-cells = <1>;
+		};
+	};
-- 
1.9.1