ENGR00318895-5 Documentation: mtd: add a new document for SPI NOR flash

We need a DT property to store the dummy cycles for DDR Quad read.
This is a common feature for the SPI NOR flash, such as Spansion and Micron
chips.

Add this file to describe this specific SPI NOR flash features which will
be referred by the SPI NOR flash drivers.

Signed-off-by: Huang Shijie <b32955@freescale.com>
(cherry picked from commit dfbe3eb5c7c2c3967c0f1bf32c0279136da7bfce)

diff --git a/Documentation/devicetree/bindings/mtd/spi-nor-flash.txt b/Documentation/devicetree/bindings/mtd/spi-nor-flash.txt
new file mode 100644 (file)
index 0000000..aba4d54
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/spi-nor-flash.txt
@@ -0,0 +1,7 @@
+This file defines some DT properties for specific SPI NOR flash features.
+The SPI NOR controller drivers may refer to this file, such as fsl-quadspi.txt
+
+Optional properties:
+  - spi-nor,ddr-quad-read-dummy: The dummy cycles used by the DDR Quad read.
+                                 Please refer to the chip's datasheet. This
+                                 property can be 4 or 6 which is less then 8.