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author | Maxime Ripard <maxime.ripard@bootlin.com> | 2019-05-20 16:50:33 +0200 |
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committer | Mark Brown <broonie@kernel.org> | 2019-05-21 21:25:08 +0100 |
commit | 0a1b929356830257568f9547e173f0e7498060ea (patch) | |
tree | 3fabbb5e1f4bc79dd373ad46eed42f097ad2e634 /Documentation/devicetree/bindings/spi/spi-bus.txt | |
parent | 9783da2384c5623d376e4641bbce9339be1001eb (diff) | |
download | linux-0a1b929356830257568f9547e173f0e7498060ea.tar.gz |
spi: Add YAML schemas for the generic SPI options
The SPI controllers have a bunch of generic options that are needed in a
device tree. Add a YAML schemas for those.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'Documentation/devicetree/bindings/spi/spi-bus.txt')
-rw-r--r-- | Documentation/devicetree/bindings/spi/spi-bus.txt | 112 |
1 files changed, 1 insertions, 111 deletions
diff --git a/Documentation/devicetree/bindings/spi/spi-bus.txt b/Documentation/devicetree/bindings/spi/spi-bus.txt index 1f6e86f787ef..e07783505498 100644 --- a/Documentation/devicetree/bindings/spi/spi-bus.txt +++ b/Documentation/devicetree/bindings/spi/spi-bus.txt @@ -1,111 +1 @@ -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>; - }; - }; +This file has moved to spi-controller.yaml. |