From e3d786a3745473e905e68aa918b1543c6f9da67c Mon Sep 17 00:00:00 2001 From: Matheus Tavares Date: Fri, 23 Nov 2018 22:23:09 -0200 Subject: [PATCH] dt-bindings:iio:resolver: Add docs for ad2s90 This patch adds the device tree binding documentation for the ad2s90 resolver-to-digital converter. Signed-off-by: Matheus Tavares Reviewed-by: Rob Herring Acked-by: Alexandru Ardelean Signed-off-by: Jonathan Cameron --- .../bindings/iio/resolver/ad2s90.txt | 31 +++++++++++++++++++ 1 file changed, 31 insertions(+) create mode 100644 Documentation/devicetree/bindings/iio/resolver/ad2s90.txt diff --git a/Documentation/devicetree/bindings/iio/resolver/ad2s90.txt b/Documentation/devicetree/bindings/iio/resolver/ad2s90.txt new file mode 100644 index 000000000000..477d41fa6467 --- /dev/null +++ b/Documentation/devicetree/bindings/iio/resolver/ad2s90.txt @@ -0,0 +1,31 @@ +Analog Devices AD2S90 Resolver-to-Digital Converter + +https://www.analog.com/en/products/ad2s90.html + +Required properties: + - compatible: should be "adi,ad2s90" + - reg: SPI chip select number for the device + - spi-max-frequency: set maximum clock frequency, must be 830000 + - spi-cpol and spi-cpha: + Either SPI mode (0,0) or (1,1) must be used, so specify none or both of + spi-cpha, spi-cpol. + +See for more details: + Documentation/devicetree/bindings/spi/spi-bus.txt + +Note about max frequency: + Chip's max frequency, as specified in its datasheet, is 2Mhz. But a 600ns + delay is expected between the application of a logic LO to CS and the + application of SCLK, as also specified. And since the delay is not + implemented in the spi code, to satisfy it, SCLK's period should be at most + 2 * 600ns, so the max frequency should be 1 / (2 * 6e-7), which gives + roughly 830000Hz. + +Example: +resolver@0 { + compatible = "adi,ad2s90"; + reg = <0>; + spi-max-frequency = <830000>; + spi-cpol; + spi-cpha; +}; -- 2.30.2