From 0c2416ea7fd5ae15af079f11947902c4e7b51364 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nicol=C3=A1s=20A=2E=20M=C3=A9ndez?=
 <naikymen@users.noreply.github.com>
Date: Tue, 24 Mar 2026 13:51:44 -0300
Subject: [PATCH] avr: Fix missing SP definition in newer avr-libc and missing
 include in adc.c (#7233)
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compatibility fix for newer avr-libc - define stack pointer

add missing avr/io.h include to adc.c

add missing avr/io.h include to spi.c

Signed-off-by: Nicolás Méndez <9phhsyrbm@relay.firefox.com>
---
 src/avr/adc.c  | 1 +
 src/avr/main.c | 6 ++++++
 src/avr/spi.c  | 1 +
 3 files changed, 8 insertions(+)

diff --git a/src/avr/adc.c b/src/avr/adc.c
index 99fd063f6..e94dfbc57 100644
--- a/src/avr/adc.c
+++ b/src/avr/adc.c
@@ -4,6 +4,7 @@
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
+#include <avr/io.h> // ADCSRA
 #include "autoconf.h" // CONFIG_MACH_atmega644p
 #include "command.h" // shutdown
 #include "gpio.h" // gpio_adc_read
diff --git a/src/avr/main.c b/src/avr/main.c
index 0523af411..b0d299dac 100644
--- a/src/avr/main.c
+++ b/src/avr/main.c
@@ -12,6 +12,12 @@
 #include "irq.h" // irq_enable
 #include "sched.h" // sched_main
 
+// Newer avr-libc headers expose the stack pointer as SP instead of the
+// older AVR_STACK_POINTER_REG alias used by Klipper.
+#ifndef AVR_STACK_POINTER_REG
+#define AVR_STACK_POINTER_REG SP
+#endif
+
 DECL_CONSTANT_STR("MCU", CONFIG_MCU);
 
 
diff --git a/src/avr/spi.c b/src/avr/spi.c
index 55eb1f58c..d8acd45da 100644
--- a/src/avr/spi.c
+++ b/src/avr/spi.c
@@ -4,6 +4,7 @@
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
+#include <avr/io.h> // SPCR
 #include "autoconf.h" // CONFIG_MACH_atmega644p
 #include "command.h" // shutdown
 #include "gpio.h" // spi_setup