[PATCH 4/7] Documentation: mtd: add a DT property to set the latency code of Spansion memory
From: Cyrille Pitchen <hidden>
Date: 2015-07-16 15:27:51
Also in:
linux-devicetree, linux-spi, lkml
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
Both the SPI controller and the NOR flash memory need to agree on the number of dummy cycles to use for Fast Read commands. For Spansion memories, this number of dummy cycles is not given directly but through a so called "latency code". The latency code can be found into the memory datasheet and depends on the SPI clock frequency, the Fast Read op code and the Single/Dual Data Rate mode. Signed-off-by: Cyrille Pitchen <redacted> --- .../devicetree/bindings/mtd/spansion-nor.txt | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 Documentation/devicetree/bindings/mtd/spansion-nor.txt
diff --git a/Documentation/devicetree/bindings/mtd/spansion-nor.txt b/Documentation/devicetree/bindings/mtd/spansion-nor.txt
new file mode 100644
index 000000000000..a55c62db0e6f
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/spansion-nor.txt@@ -0,0 +1,22 @@ +* Spansion NOR flash + +Optional properties: +- spansion,latency-code : Only used when the "m25p,num-dummy-cycles" property is + set. The Spansion latency code tells the NOR flash + memory the number of dummy cycles to expect for each + Fast Read command. The value to be used is provided by + tables in the memory datasheet and depends on the SPI + clock frequency and on the Single/Dual Data Rate mode. + Then the value of "m25p,num-dummy-cycles" property + should match the (Fast) Read command to be used for + the chosen latency code. + +Example: + + m25p80 at 0 { + compatible = "spansion,s25fl512s"; + reg = <0>; + spi-max-frequency = <104000000>; + m25p,num-dummy-cycles = <8>; + spansion,latency-code = <2>; + };
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1.8.2.2