Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 111 insertions, 0 deletions

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