From 384e12708569ec92a1229c44fa09eb5ddd32a728 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mario=20H=C3=BCttel?= <mario.huettel@gmx.net>
Date: Thu, 20 May 2021 23:55:32 +0200
Subject: [PATCH] Add first draft of memory checking for CCM RAM

---
 stm-firmware/boot/startup-tests.c       | 64 +++++++++++++++++++++++++
 stm-firmware/boot/startup-tests.h       | 18 +++++++
 stm-firmware/boot/startup_stm32f407vx.c |  5 ++
 3 files changed, 87 insertions(+)
 create mode 100644 stm-firmware/boot/startup-tests.c
 create mode 100644 stm-firmware/boot/startup-tests.h

diff --git a/stm-firmware/boot/startup-tests.c b/stm-firmware/boot/startup-tests.c
new file mode 100644
index 0000000..6eacdd8
--- /dev/null
+++ b/stm-firmware/boot/startup-tests.c
@@ -0,0 +1,64 @@
+#include "startup-tests.h"
+
+uint32_t startup_test_perform_ccm_ram_check(void)
+{
+	const void *ccmram_base = (void *)0x10000000UL;
+	const uint32_t ccmram_size = 64U * 1024UL;
+	volatile uint32_t *word_ptr;
+	uint32_t target_val;
+	uint32_t idx;
+	uint32_t ret = 0UL;
+
+
+	/* Perform inversion test with 0x55 and 0xAA, Part 1 */
+	for (idx = 0, word_ptr = (volatile uint32_t *)ccmram_base; idx < ccmram_size / 4U; idx++) {
+		word_ptr[idx] = idx & 1 ? 0x55AA55AAUL : 0xAA55AA55UL;
+	}
+	for (idx = 0, word_ptr = (volatile uint32_t *)ccmram_base; idx < ccmram_size / 4U; idx++) {
+		target_val = idx & 1 ? 0x55AA55AAUL : 0xAA55AA55UL;
+		if (target_val != word_ptr[idx]) {
+			ret = (uint32_t)&word_ptr[idx];
+			goto exit_ret_address;
+		}
+	}
+
+	/* Perform inversion test with 0x55 and 0xAA, Part 2 */
+	for (idx = 0, word_ptr = (volatile uint32_t *)ccmram_base; idx < ccmram_size / 4U; idx++) {
+		word_ptr[idx] = idx & 1 ? 0xAA55AA55UL : 0x55AA55AAUL;
+	}
+	for (idx = 0, word_ptr = (volatile uint32_t *)ccmram_base; idx < ccmram_size / 4U; idx++) {
+		target_val = idx & 1 ? 0x55AA55AAUL : 0xAA55AA55UL;
+		if (target_val != word_ptr[idx]) {
+			ret = (uint32_t)&word_ptr[idx];
+			goto exit_ret_address;
+		}
+	}
+
+	/* Perform static test with 0xFF */
+	for (idx = 0, word_ptr = (volatile uint32_t *)ccmram_base; idx < ccmram_size / 4U; idx++) {
+		word_ptr[idx] = 0xFFFFFFFFUL;
+	}
+	for (idx = 0, word_ptr = (volatile uint32_t *)ccmram_base; idx < ccmram_size / 4U; idx++) {
+		target_val = 0xFFFFFFFFUL;
+		if (target_val != word_ptr[idx]) {
+			ret = (uint32_t)&word_ptr[idx];
+			goto exit_ret_address;
+		}
+	}
+
+	/* Perform static test with 0x00 */
+	for (idx = 0, word_ptr = (volatile uint32_t *)ccmram_base; idx < ccmram_size / 4U; idx++) {
+		word_ptr[idx] = 0x0UL;
+	}
+	for (idx = 0, word_ptr = (volatile uint32_t *)ccmram_base; idx < ccmram_size / 4U; idx++) {
+		target_val = 0x0UL;
+		if (target_val != word_ptr[idx]) {
+			ret = (uint32_t)&word_ptr[idx];
+			goto exit_ret_address;
+		}
+	}
+
+
+exit_ret_address:
+	return ret;
+}
diff --git a/stm-firmware/boot/startup-tests.h b/stm-firmware/boot/startup-tests.h
new file mode 100644
index 0000000..90ebdb9
--- /dev/null
+++ b/stm-firmware/boot/startup-tests.h
@@ -0,0 +1,18 @@
+#ifndef _STARTUP_TESTS_H_
+#define _STARTUP_TESTS_H_
+
+#include <stdint.h>
+
+/**
+ * @brief Do a RAM check of the CCM RAM.
+ *
+ * Loop over the whole CCM memory area and check it.
+ *
+ * @return 0 if successful. Else the defect address is returned.
+ * @warning This will completely corrupt this memory!
+ * You have to ensure to set it to sane values afterwards!
+ */
+uint32_t startup_test_perform_ccm_ram_check(void);
+
+
+#endif /* _STARTUP_TESTS_H_ */
diff --git a/stm-firmware/boot/startup_stm32f407vx.c b/stm-firmware/boot/startup_stm32f407vx.c
index c6fb891..d159ff5 100644
--- a/stm-firmware/boot/startup_stm32f407vx.c
+++ b/stm-firmware/boot/startup_stm32f407vx.c
@@ -19,6 +19,7 @@
 */
 
 #include <stdint.h>
+#include "startup-tests.h"
 
 /* C++ library init */
 # if defined(__cplusplus)
@@ -297,6 +298,10 @@ void Reset_Handler(void) {
 	 */
 	CPACR |= (0xF << 20);
 
+	if (startup_test_perform_ccm_ram_check()) {
+		/* Hang forever in case of an error. We cannot handle this (yet?) */
+		while (1);
+	}
 
 	/* Copy .data section */
 	__init_section(&__ld_load_data, &__ld_sdata, &__ld_edata);