From 623f4a862134202e9f0705812cabe2abef6c2f9b Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Mon, 31 Jan 2022 21:01:25 +0000
Subject: [PATCH] overlays: Add spi0-0cs overlay

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

Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
 arch/arm/boot/dts/overlays/Makefile           |  1 +
 arch/arm/boot/dts/overlays/README             |  8 ++++
 .../boot/dts/overlays/spi0-0cs-overlay.dts    | 39 +++++++++++++++++++
 3 files changed, 48 insertions(+)
 create mode 100644 arch/arm/boot/dts/overlays/spi0-0cs-overlay.dts

--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -195,6 +195,7 @@ 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 \
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -3115,6 +3115,14 @@ Params: ds3232                  Select t
         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>
--- /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";
+	};
+};