-
Notifications
You must be signed in to change notification settings - Fork 0
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
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>
- Loading branch information
Maxime Ripard
authored and
Mark Brown
committed
May 21, 2019
1 parent
9783da2
commit 0a1b929
Showing
2 changed files
with
162 additions
and
111 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -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. |
161 changes: 161 additions & 0 deletions
161
Documentation/devicetree/bindings/spi/spi-controller.yaml
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,161 @@ | ||
# SPDX-License-Identifier: GPL-2.0 | ||
%YAML 1.2 | ||
--- | ||
$id: http://devicetree.org/schemas/spi/spi-controller.yaml# | ||
$schema: http://devicetree.org/meta-schemas/core.yaml# | ||
|
||
title: SPI Controller Generic Binding | ||
|
||
maintainers: | ||
- Mark Brown <broonie@kernel.org> | ||
|
||
description: | | ||
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 SPI | ||
controller may be described for use in SPI master mode or in SPI slave mode, | ||
but not for both at the same time. | ||
properties: | ||
$nodename: | ||
pattern: "^spi(@.*|-[0-9a-f])*$" | ||
|
||
"#address-cells": | ||
const: 1 | ||
|
||
"#size-cells": | ||
const: 0 | ||
|
||
cs-gpios: | ||
description: | | ||
GPIOs used as chip selects. | ||
If that property is used, the number of chip selects will be | ||
increased automatically with max(cs-gpios, hardware chip selects). | ||
So if, for example, the controller has 2 CS lines, and the | ||
cs-gpios 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 | ||
num-cs: | ||
$ref: /schemas/types.yaml#/definitions/uint32 | ||
description: | ||
Total number of chip selects. | ||
|
||
spi-slave: | ||
$ref: /schemas/types.yaml#/definitions/flag | ||
description: | ||
The SPI controller acts as a slave, instead of a master. | ||
|
||
patternProperties: | ||
"^slave$": | ||
type: object | ||
|
||
properties: | ||
compatible: | ||
description: | ||
Compatible of the SPI device. | ||
|
||
required: | ||
- compatible | ||
|
||
"^.*@[0-9a-f]+$": | ||
type: object | ||
|
||
properties: | ||
compatible: | ||
description: | ||
Compatible of the SPI device. | ||
|
||
reg: | ||
maxItems: 1 | ||
minimum: 0 | ||
maximum: 256 | ||
description: | ||
Chip select used by the device. | ||
|
||
spi-3wire: | ||
$ref: /schemas/types.yaml#/definitions/flag | ||
description: | ||
The device requires 3-wire mode. | ||
|
||
spi-cpha: | ||
$ref: /schemas/types.yaml#/definitions/flag | ||
description: | ||
The device requires shifted clock phase (CPHA) mode. | ||
|
||
spi-cpol: | ||
$ref: /schemas/types.yaml#/definitions/flag | ||
description: | ||
The device requires inverse clock polarity (CPOL) mode. | ||
|
||
spi-cs-high: | ||
$ref: /schemas/types.yaml#/definitions/flag | ||
description: | ||
The device requires the chip select active high. | ||
|
||
spi-lsb-first: | ||
$ref: /schemas/types.yaml#/definitions/flag | ||
description: | ||
The device requires the LSB first mode. | ||
|
||
spi-max-frequency: | ||
$ref: /schemas/types.yaml#/definitions/uint32 | ||
description: | ||
Maximum SPI clocking speed of the device in Hz. | ||
|
||
spi-rx-bus-width: | ||
allOf: | ||
- $ref: /schemas/types.yaml#/definitions/uint32 | ||
- enum: [ 1, 2, 4 ] | ||
- default: 1 | ||
description: | ||
Bus width to the SPI bus used for MISO. | ||
|
||
spi-rx-delay-us: | ||
description: | ||
Delay, in microseconds, after a read transfer. | ||
|
||
spi-tx-bus-width: | ||
allOf: | ||
- $ref: /schemas/types.yaml#/definitions/uint32 | ||
- enum: [ 1, 2, 4 ] | ||
- default: 1 | ||
description: | ||
Bus width to the SPI bus used for MOSI. | ||
|
||
spi-tx-delay-us: | ||
description: | ||
Delay, in microseconds, after a write transfer. | ||
|
||
required: | ||
- compatible | ||
- reg | ||
|
||
examples: | ||
- | | ||
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>; | ||
}; | ||
}; |