[PATCH v9 1/3] doc: dt: add cyclone-ps-spi binding document

[Joshua Clayton]

Describe a cyclone-ps-spi devicetree entry, required features

Signed-off-by: Joshua Clayton <stillcompiling at gmail.com>
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 .../bindings/fpga/altera-passive-serial.txt        | 29 ++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/fpga/altera-passive-serial.txt

diff --git a/Documentation/devicetree/bindings/fpga/altera-passive-serial.txt b/Documentation/devicetree/bindings/fpga/altera-passive-serial.txt
new file mode 100644
index 0000000..774e6a7
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+++ b/Documentation/devicetree/bindings/fpga/altera-passive-serial.txt
@@ -0,0 +1,29 @@
+Altera Cyclone Passive Serial SPI FPGA Manager
+
+Altera Cyclone FPGAs support a method of loading the bitstream over what is
+referred to as "passive serial".
+The passive serial link is not technically spi, and might require extra
+circuits in order to play nicely with other spi slaves on the same bus.
+
+See https://www.altera.com/literature/hb/cyc/cyc_c51013.pdf
+
+Required properties:
+- compatible: should contain "altr,fpga-passive-serial"
+- reg: spi chip select of the FPGA
+- nconfig-gpios: config pin (referred to as nCONFIG in the cyclone manual)
+- nstat-gpios: status pin (referred to as nSTATUS in the cyclone manual)
+
+Optional properties:
+- confd-gpios: confd pin (referred to as CONF_DONE in the cyclone manual)
+
+
+
+Example:
+	fpga_spi: evi-fpga-spi at 0 {
+		compatible = "altr,cyclone-ps-spi-fpga-mgr";
+		spi-max-frequency = <20000000>;
+		reg = <0>;
+		nconfig-gpios = <&gpio4 9 GPIO_ACTIVE_LOW>;
+		nstat-gpios = <&gpio4 11 GPIO_ACTIVE_LOW>;
+		confd-gpios = <&gpio4 12 GPIO_ACTIVE_LOW>;
+	};
-- 
2.9.3