On 10/07/2016 07:25 AM, Ralf Ramsauer wrote:
Hi,
I'm running a Jetson TK1 on mainline Linux. To enable userspace SPI, I
modified the device-tree by:
/* Expansion TS_SPI_* */
spi@7000d400 {
status = "okay";
+ spidev@0 {
+ compatible = "spidev";
+ reg = <0>;
+ spi-max-frequency = <25000000>;
+ };
};
This works fine. Is it possible to use arbitrary GPIOs as additional
chip-selects?
What would I have to do If I'd like to add PU0 or PU1 (sysfs
gpio160/161) as chip-selects?
According to Documentation/devicetree/bindings/spi/spi-bus.txt, there
are standard properties you can use for GPIO chip-select signals, and it
looks like the SPI core code handles this itself. However, judging by a
quick look at the Tegra SPI driver, it doesn't fully support that since
it always attempts to program the HW chip-selects. If you make the HW CS
logic in the driver conditional, and add the DT properties mentioned in
spi-bus.txt, it should work.
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