mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-17 08:43:07 +00:00
32466c445c
Linux bindings have been introduced in the code (removing the U-Boot
specific ones) without documentation update. Compatible string has
changed, as well as the four GPIO properties. Reflect this by updating
the soft-spi.txt documentation.
Fixes: 102412c415 ("dm: spi: soft_spi: switch to use linux compatible string")
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
38 lines
1.1 KiB
Text
38 lines
1.1 KiB
Text
Soft SPI
|
|
|
|
The soft SPI bus implementation allows the use of GPIO pins to simulate a
|
|
SPI bus. No SPI host is required for this to work. The down-side is that the
|
|
performance will typically be much lower than a real SPI bus.
|
|
|
|
The soft SPI node requires the following properties:
|
|
|
|
Mandatory properties:
|
|
compatible: "spi-gpio"
|
|
cs-gpios: GPIOs to use for SPI chip select (output)
|
|
gpio-sck: GPIO to use for SPI clock (output)
|
|
And at least one of:
|
|
gpio-mosi: GPIO to use for SPI MOSI line (output)
|
|
gpio-miso: GPIO to use for SPI MISO line (input)
|
|
|
|
Optional propertie:
|
|
spi-delay-us: Number of microseconds of delay between each CS transition
|
|
|
|
The GPIOs should be specified as required by the GPIO controller referenced.
|
|
The first cell holds the phandle of the controller and the second cell
|
|
typically holds the GPIO number.
|
|
|
|
|
|
Example:
|
|
|
|
soft-spi {
|
|
compatible = "spi-gpio";
|
|
cs-gpios = <&gpio 235 0>; /* Y43 */
|
|
gpio-sck = <&gpio 225 0>; /* Y31 */
|
|
gpio-mosi = <&gpio 227 0>; /* Y33 */
|
|
gpio-miso = <&gpio 224 0>; /* Y30 */
|
|
spi-delay-us = <1>;
|
|
#address-cells = <1>;
|
|
#size-cells = <0>;
|
|
cs@0 {
|
|
};
|
|
};
|