From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matheus Tavares Subject: [PATCH 4/6] dt-bindings:iio:resolver: Add docs for ad2s90 Date: Fri, 9 Nov 2018 20:00:42 -0200 Message-ID: <20181109220044.24843-5-matheus.bernardino@usp.br> References: <20181109220044.24843-1-matheus.bernardino@usp.br> Return-path: In-Reply-To: <20181109220044.24843-1-matheus.bernardino@usp.br> Sender: linux-kernel-owner@vger.kernel.org To: Lars-Peter Clausen , Michael Hennerich , Jonathan Cameron , Hartmut Knaack , Peter Meerwald-Stadler , Greg Kroah-Hartman , Rob Herring , Mark Rutland Cc: linux-iio@vger.kernel.org, devel@driverdev.osuosl.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Alexandru Ardelean , kernel-usp@googlegroups.com, victorcolombo@gmail.com List-Id: devicetree@vger.kernel.org This patch adds the device tree binding documentation for the ad2s90 resolver-to-digital converter. Signed-off-by: Matheus Tavares --- .../bindings/iio/resolver/ad2s90.txt | 26 +++++++++++++++++++ 1 file changed, 26 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..b42cc7752ffd --- /dev/null +++ b/Documentation/devicetree/bindings/iio/resolver/ad2s90.txt @@ -0,0 +1,26 @@ +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 : must be defined to enable SPI mode 3 + +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; +}; -- 2.18.0