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dt-bindings: olpc,xo1.75-ec: Add OLPC XO-1.75 EC bindings 

The OLPC XO-1.75 Embedded Controller is a SPI master that uses extra
signals for handshaking. It needs to know when is the slave (Linux)
side's TX FIFO ready for transfer (the ready-gpio signal on the SPI
controller node) and when does it wish to respond with a command (the
cmd-gpio property).

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
This commit is contained in:
Lubomir Rintel 2019-05-13 09:56:32 +02:00 committed by Andy Shevchenko
parent d6423bd030
commit f22558d701
1 changed files with 23 additions and 0 deletions
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Documentation/devicetree/bindings/misc/olpc,xo1.75-ec.txt Normal file
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OLPC XO-1.75 Embedded Controller
Required properties:
- compatible: Should be "olpc,xo1.75-ec".
- cmd-gpios: gpio specifier of the CMD pin
The embedded controller requires the SPI controller driver to signal readiness
to receive a transfer (that is, when TX FIFO contains the response data) by
strobing the ACK pin with the ready signal. See the "ready-gpios" property of the
SSP binding as documented in:
<Documentation/devicetree/bindings/spi/spi-pxa2xx.txt>.
Example:
&ssp3 {
spi-slave;
ready-gpios = <&gpio 125 GPIO_ACTIVE_HIGH>;
slave {
compatible = "olpc,xo1.75-ec";
spi-cpha;
cmd-gpios = <&gpio 155 GPIO_ACTIVE_HIGH>;
};
};