debug_irq_disable: add module to debug time spent in irq_disable

sys/Kconfig

@@ -25,6 +25,7 @@ rsource "congure/Kconfig"
 rsource "cpp11-compat/Kconfig"
 rsource "cpp_new_delete/Kconfig"
 rsource "cxx_ctor_guards/Kconfig"
+rsource "debug_irq_disable/Kconfig"
 rsource "div/Kconfig"
 rsource "embunit/Kconfig"
 rsource "entropy_source/Kconfig"

sys/Makefile.dep

@@ -65,6 +65,10 @@ ifneq (,$(filter crc32_fast,$(USEMODULE)))
   USEMODULE += checksum
 endif
 
+ifneq (,$(filter debug_irq_disable,$(USEMODULE)))
+  USEMODULE += fmt
+endif
+
 ifneq (,$(filter eepreg,$(USEMODULE)))
   FEATURES_REQUIRED += periph_eeprom
 endif

sys/debug_irq_disable/Kconfig

@@ -0,0 +1,21 @@
+# Copyright (C) 2022 Benjamin Valentin
+#
+# This file is subject to the terms and conditions of the GNU Lesser
+# General Public License v2.1. See the file LICENSE in the top level
+# directory for more details.
+#
+
+menuconfig MODULE_DEBUG_IRQ_DISABLE
+    bool "Measure IRQ disable durations"
+    depends on TEST_KCONFIG
+    depends on CPU_CORE_CORTEX_M
+    help
+        Print time spent with IRQs disabled
+
+config DEBUG_IRQ_DISABLE_THRESHOLD
+    int "Suppress Threshold"
+    default 1
+    depends on MODULE_DEBUG_IRQ_DISABLE
+    help
+        Threshold (in CPU ticks) below which periods with IRQs disabled are not printed.
+        Use this to prevent *a lot* of output when debugging.

sys/debug_irq_disable/Makefile

@@ -0,0 +1 @@
+include $(RIOTBASE)/Makefile.base

sys/debug_irq_disable/debug_irq_disable.c

@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2022 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     debug_irq_disable
+ * @{
+ *
+ * @file
+ * @brief       Helper for debug_irq_disable
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ * @}
+ */
+
+#include <stdbool.h>
+#include "fmt.h"
+
+void debug_irq_disable_print(const char *file, unsigned line, uint32_t ticks)
+{
+    static bool is_printing;
+
+    if (is_printing) {
+        return;
+    }
+
+    /* prevent infinite recursion if stdio driver uses irq_disable()  */
+    is_printing = true;
+
+    print_str("irq disabled for ");
+    print_u32_dec(ticks);
+    print_str(" ticks in ");
+    print_str(file);
+    print_str(":");
+    print_u32_dec(line);
+    print_str("\n");
+
+    is_printing = false;
+}

sys/include/debug_irq_disable.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2022 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @defgroup    debug_irq_disable IRQ Disable Debug helper
+ * @ingroup     sys
+ * @brief       Debug time spent with IRQ disabled
+ * @{
+ *
+ * @file
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ */
+
+#ifndef DEBUG_IRQ_DISABLE_H
+#define DEBUG_IRQ_DISABLE_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Print time spent with IRQ disabled
+ * @internal
+ *
+ * @param[in] file  file where irq_restore() was called
+ * @param[in] line  line where irq_restore() was called
+ * @param[in] ticks CPU ticks spent with IRQ disabled
+ */
+void debug_irq_disable_print(const char *file, unsigned line, uint32_t ticks);
+
+#ifdef __cplusplus
+}
+#endif
+
+/** @} */
+#endif /* DEBUG_IRQ_DISABLE_H */