overlays: Add spi0-0cs overlay

An overlay to enable SPI0 without claiming any chip select GPIOs.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

diff --git a/arch/arm/boot/dts/overlays/Makefile b/arch/arm/boot/dts/overlays/Makefile
index bff07c1..f51eca4 100644 (file)
--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -194,6 +194,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
        spi-gpio35-39.dtbo \
        spi-gpio40-45.dtbo \
        spi-rtc.dtbo \
+       spi0-0cs.dtbo \
        spi0-1cs.dtbo \
        spi0-2cs.dtbo \
        spi1-1cs.dtbo \

diff --git a/arch/arm/boot/dts/overlays/README b/arch/arm/boot/dts/overlays/README
index f124086..0a2f62f 100644 (file)
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -3098,6 +3098,14 @@ Params: ds3232                  Select the DS3232 device
         cs_high                 This device requires an active-high CS
 
 
+Name:   spi0-0cs
+Info:   Don't claim any CS pins for SPI0. Requires a device with its chip
+        select permanently enabled, but frees a GPIO for e.g. a DPI display.
+Load:   dtoverlay=spi0-0cs,<param>=<val>
+Params: no_miso                 Don't claim and use the MISO pin (9), freeing
+                                it for other uses.
+
+
 Name:   spi0-1cs
 Info:   Only use one CS pin for SPI0
 Load:   dtoverlay=spi0-1cs,<param>=<val>

diff --git a/arch/arm/boot/dts/overlays/spi0-0cs-overlay.dts b/arch/arm/boot/dts/overlays/spi0-0cs-overlay.dts
new file mode 100644 (file)
index 0000000..0d2acab
--- /dev/null
+++ b/arch/arm/boot/dts/overlays/spi0-0cs-overlay.dts
@@ -0,0 +1,39 @@
+/dts-v1/;
+/plugin/;
+
+/ {
+       compatible = "brcm,bcm2835";
+
+       fragment@0 {
+               target = <&spi0_cs_pins>;
+               frag0: __overlay__ {
+                       brcm,pins;
+               };
+       };
+
+       fragment@1 {
+               target = <&spi0>;
+               __overlay__ {
+                       cs-gpios;
+                       status = "okay";
+               };
+       };
+
+       fragment@2 {
+               target = <&spidev1>;
+               __overlay__ {
+                       status = "disabled";
+               };
+       };
+
+       fragment@3 {
+               target = <&spi0_pins>;
+               __dormant__ {
+                       brcm,pins = <10 11>;
+               };
+       };
+
+       __overrides__ {
+               no_miso = <0>,"=3";
+       };
+};