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2023-12-08 01573e231f18eb2d99162747186f59511f56b64d 
 kernel/Documentation/devicetree/bindings/spi/spi-bus.txt
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-SPI (Serial Peripheral Interface) busses
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-
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-SPI busses can be described with a node for the SPI controller device
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-and a set of child nodes for each SPI slave on the bus.  The system's SPI
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-controller may be described for use in SPI master mode or in SPI slave mode,
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-but not for both at the same time.
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-
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-The SPI controller node requires the following properties:
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-- compatible      - Name of SPI bus controller following generic names
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-		    recommended practice.
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-
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-In master mode, the SPI controller node requires the following additional
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-properties:
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-- #address-cells  - number of cells required to define a chip select
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-		address on the SPI bus.
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-- #size-cells     - should be zero.
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-
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-In slave mode, the SPI controller node requires one additional property:
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-- spi-slave       - Empty property.
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-
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-No other properties are required in the SPI bus node.  It is assumed
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-that a driver for an SPI bus device will understand that it is an SPI bus.
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-However, the binding does not attempt to define the specific method for
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-assigning chip select numbers.  Since SPI chip select configuration is
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-flexible and non-standardized, it is left out of this binding with the
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-assumption that board specific platform code will be used to manage
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-chip selects.  Individual drivers can define additional properties to
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-support describing the chip select layout.
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-
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-Optional properties (master mode only):
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-- cs-gpios	  - gpios chip select.
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-- num-cs	  - total number of chipselects.
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-
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-If cs-gpios is used the number of chip selects will be increased automatically
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-with max(cs-gpios > hw cs).
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-
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-So if for example the controller has 2 CS lines, and the cs-gpios
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-property looks like this:
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-
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-cs-gpios = <&gpio1 0 0>, <0>, <&gpio1 1 0>, <&gpio1 2 0>;
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-
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-Then it should be configured so that num_chipselect = 4 with the
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-following mapping:
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-
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-cs0 : &gpio1 0 0
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-cs1 : native
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-cs2 : &gpio1 1 0
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-cs3 : &gpio1 2 0
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-
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-
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-SPI slave nodes must be children of the SPI controller node.
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-
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-In master mode, one or more slave nodes (up to the number of chip selects) can
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-be present.  Required properties are:
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-- compatible      - Name of SPI device following generic names recommended
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-		    practice.
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-- reg             - Chip select address of device.
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-- spi-max-frequency - Maximum SPI clocking speed of device in Hz.
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-
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-In slave mode, the (single) slave node is optional.
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-If present, it must be called "slave".  Required properties are:
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-- compatible      - Name of SPI device following generic names recommended
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-		    practice.
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-
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-All slave nodes can contain the following optional properties:
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-- spi-cpol        - Empty property indicating device requires inverse clock
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-		    polarity (CPOL) mode.
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-- spi-cpha        - Empty property indicating device requires shifted clock
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-		    phase (CPHA) mode.
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-- spi-cs-high     - Empty property indicating device requires chip select
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-		    active high.
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-- spi-3wire       - Empty property indicating device requires 3-wire mode.
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-- spi-lsb-first   - Empty property indicating device requires LSB first mode.
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-- spi-tx-bus-width - The bus width (number of data wires) that is used for MOSI.
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-		    Defaults to 1 if not present.
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-- spi-rx-bus-width - The bus width (number of data wires) that is used for MISO.
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-		    Defaults to 1 if not present.
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-- spi-rx-delay-us - Microsecond delay after a read transfer.
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-- spi-tx-delay-us - Microsecond delay after a write transfer.
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-
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-Some SPI controllers and devices support Dual and Quad SPI transfer mode.
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-It allows data in the SPI system to be transferred using 2 wires (DUAL) or 4
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-wires (QUAD).
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-Now the value that spi-tx-bus-width and spi-rx-bus-width can receive is
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-only 1 (SINGLE), 2 (DUAL) and 4 (QUAD).
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-Dual/Quad mode is not allowed when 3-wire mode is used.
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-
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-If a gpio chipselect is used for the SPI slave the gpio number will be passed
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-via the SPI master node cs-gpios property.
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-
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-SPI example for an MPC5200 SPI bus:
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-	spi@f00 {
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-		#address-cells = <1>;
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-		#size-cells = <0>;
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-		compatible = "fsl,mpc5200b-spi","fsl,mpc5200-spi";
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-		reg = <0xf00 0x20>;
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-		interrupts = <2 13 0 2 14 0>;
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-		interrupt-parent = <&mpc5200_pic>;
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-
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-		ethernet-switch@0 {
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-			compatible = "micrel,ks8995m";
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-			spi-max-frequency = <1000000>;
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-			reg = <0>;
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-		};
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-
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-		codec@1 {
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-			compatible = "ti,tlv320aic26";
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-			spi-max-frequency = <100000>;
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-			reg = <1>;
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-		};
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-	};
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+This file has moved to spi-controller.yaml.