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3a5584e0df
Adds latest 6.6 patches from the Raspberry Pi repository. These patches were generated from: https://github.com/raspberrypi/linux/commits/rpi-6.6.y/ With the following command: git format-patch -N v6.6.67..HEAD (HEAD -> 811ff707533bcd67cdcd368bbd46223082009b12) Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com> (cherry picked from commit 692205305db14deeff1a2dc4a6d7f87e19fc418b)
109 lines
3.0 KiB
Diff
109 lines
3.0 KiB
Diff
From dbf12796d1368286672529d7b03f81066a8c36f3 Mon Sep 17 00:00:00 2001
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From: Iker Pedrosa <ikerpedrosam@gmail.com>
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Date: Mon, 18 Nov 2024 10:55:33 +0100
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Subject: [PATCH] dtoverlays: enable SPI CS active-high
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The documentation isn't very clear explaining how to enable SPI CS
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active-high and it takes a long time to understand it. Adding a specific
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overlay as a simple example on how to invert this signal can help
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understand the solution.
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Link: https://forums.raspberrypi.com/viewtopic.php?t=378222
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Signed-off-by: Iker Pedrosa <ikerpedrosam@gmail.com>
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---
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arch/arm/boot/dts/overlays/Makefile | 1 +
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arch/arm/boot/dts/overlays/README | 8 +++
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.../overlays/spi0-1cs-inverted-overlay.dts | 59 +++++++++++++++++++
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3 files changed, 68 insertions(+)
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create mode 100644 arch/arm/boot/dts/overlays/spi0-1cs-inverted-overlay.dts
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--- a/arch/arm/boot/dts/overlays/Makefile
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+++ b/arch/arm/boot/dts/overlays/Makefile
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@@ -259,6 +259,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
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spi-rtc.dtbo \
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spi0-0cs.dtbo \
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spi0-1cs.dtbo \
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+ spi0-1cs-inverted.dtbo \
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spi0-2cs.dtbo \
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spi1-1cs.dtbo \
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spi1-2cs.dtbo \
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--- a/arch/arm/boot/dts/overlays/README
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+++ b/arch/arm/boot/dts/overlays/README
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@@ -4438,6 +4438,14 @@ Params: cs0_pin GPIO pin
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it for other uses.
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+Name: spi0-1cs-inverted
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+Info: Only use one CS pin for SPI0 and set to active-high
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+Load: dtoverlay=spi0-1cs-inverted,<param>=<val>
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+Params: cs0_pin GPIO pin for CS0 (default 8)
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+ no_miso Don't claim and use the MISO pin (9), freeing
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+ it for other uses.
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+
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+
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Name: spi0-2cs
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Info: Change the CS pins for SPI0
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Load: dtoverlay=spi0-2cs,<param>=<val>
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--- /dev/null
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+++ b/arch/arm/boot/dts/overlays/spi0-1cs-inverted-overlay.dts
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@@ -0,0 +1,59 @@
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+/dts-v1/;
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+/plugin/;
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+
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+/*
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+ * There are some devices that need an inverted Chip Select (CS) to select the
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+ * device signal, as an example the AZDelivery 12864 display. That means that
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+ * the CS polarity is active-high. To invert the CS signal the DT needs to set
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+ * the cs-gpio to GPIO_ACTIVE_HIGH (0) in the controller and set the
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+ * spi-cs-high in the peripheral property. On top of that, since this is a
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+ * display the DT also needs to specify the write-only property.
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+*/
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+
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+#include <dt-bindings/gpio/gpio.h>
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+
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+/ {
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+ compatible = "brcm,bcm2835";
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+
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+ fragment@0 {
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+ target = <&spi0_cs_pins>;
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+ frag0: __overlay__ {
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+ brcm,pins = <8>;
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+ };
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+ };
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+
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+ fragment@1 {
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+ target = <&spi0>;
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+ frag1: __overlay__ {
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+ cs-gpios = <&gpio 8 GPIO_ACTIVE_HIGH>;
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+ status = "okay";
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+ };
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+ };
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+
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+ fragment@2 {
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+ target = <&spidev1>;
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+ __overlay__ {
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+ status = "disabled";
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+ };
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+ };
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+
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+ fragment@3 {
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+ target = <&spi0_pins>;
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+ __dormant__ {
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+ brcm,pins = <10 11>;
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+ };
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+ };
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+
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+ fragment@4 {
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+ target = <&spidev0>;
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+ __overlay__ {
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+ spi-cs-high;
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+ };
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+ };
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+
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+ __overrides__ {
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+ cs0_pin = <&frag0>,"brcm,pins:0",
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+ <&frag1>,"cs-gpios:4";
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+ no_miso = <0>,"=3";
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+ };
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+};
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