diff --git a/arch/arm/boot/dts/overlays/Makefile b/arch/arm/boot/dts/overlays/Makefile index 560a63c38cc2e2..ffc1380bae77e3 100644 --- a/arch/arm/boot/dts/overlays/Makefile +++ b/arch/arm/boot/dts/overlays/Makefile @@ -259,6 +259,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \ spi-rtc.dtbo \ spi0-0cs.dtbo \ spi0-1cs.dtbo \ + spi0-1cs-inverted.dtbo \ spi0-2cs.dtbo \ spi1-1cs.dtbo \ spi1-2cs.dtbo \ diff --git a/arch/arm/boot/dts/overlays/README b/arch/arm/boot/dts/overlays/README index d1ed7f64ec5a71..c1be40a23c7b6b 100644 --- a/arch/arm/boot/dts/overlays/README +++ b/arch/arm/boot/dts/overlays/README @@ -4438,6 +4438,14 @@ Params: cs0_pin GPIO pin for CS0 (default 8) it for other uses. +Name: spi0-1cs-inverted +Info: Only use one CS pin for SPI0 and set to active-high +Load: dtoverlay=spi0-1cs-inverted,= +Params: cs0_pin GPIO pin for CS0 (default 8) + no_miso Don't claim and use the MISO pin (9), freeing + it for other uses. + + Name: spi0-2cs Info: Change the CS pins for SPI0 Load: dtoverlay=spi0-2cs,= diff --git a/arch/arm/boot/dts/overlays/spi0-1cs-inverted-overlay.dts b/arch/arm/boot/dts/overlays/spi0-1cs-inverted-overlay.dts new file mode 100644 index 00000000000000..dc1db2184df4a9 --- /dev/null +++ b/arch/arm/boot/dts/overlays/spi0-1cs-inverted-overlay.dts @@ -0,0 +1,59 @@ +/dts-v1/; +/plugin/; + +/* + * There are some devices that need an inverted Chip Select (CS) to select the + * device signal, as an example the AZDelivery 12864 display. That means that + * the CS polarity is active-high. To invert the CS signal the DT needs to set + * the cs-gpio to GPIO_ACTIVE_HIGH (0) in the controller and set the + * spi-cs-high in the peripheral property. On top of that, since this is a + * display the DT also needs to specify the write-only property. +*/ + +#include + +/ { + compatible = "brcm,bcm2835"; + + fragment@0 { + target = <&spi0_cs_pins>; + frag0: __overlay__ { + brcm,pins = <8>; + }; + }; + + fragment@1 { + target = <&spi0>; + frag1: __overlay__ { + cs-gpios = <&gpio 8 GPIO_ACTIVE_HIGH>; + status = "okay"; + }; + }; + + fragment@2 { + target = <&spidev1>; + __overlay__ { + status = "disabled"; + }; + }; + + fragment@3 { + target = <&spi0_pins>; + __dormant__ { + brcm,pins = <10 11>; + }; + }; + + fragment@4 { + target = <&spidev0>; + __overlay__ { + spi-cs-high; + }; + }; + + __overrides__ { + cs0_pin = <&frag0>,"brcm,pins:0", + <&frag1>,"cs-gpios:4"; + no_miso = <0>,"=3"; + }; +};