Write memory test for system RAM

stm-firmware/boot/startup-tests.c

@@ -62,3 +62,65 @@ uint32_t startup_test_perform_ccm_ram_check(void)
 exit_ret_address:
 	return ret;
 }
+
+uint32_t startup_test_perform_system_ram_check()
+{
+	const void *ram_base = (void *)0x20000000UL;
+	const uint32_t ram_size = 128U * 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 *)ram_base; idx < ram_size / 4U; idx++) {
+		word_ptr[idx] = idx & 1 ? 0x55AA55AAUL : 0xAA55AA55UL;
+	}
+	for (idx = 0, word_ptr = (volatile uint32_t *)ram_base; idx < ram_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 *)ram_base; idx < ram_size / 4U; idx++) {
+		word_ptr[idx] = idx & 1 ? 0xAA55AA55UL : 0x55AA55AAUL;
+	}
+	for (idx = 0, word_ptr = (volatile uint32_t *)ram_base; idx < ram_size / 4U; idx++) {
+		target_val = idx & 1 ? 0xAA55AA55UL : 0x55AA55AAUL;
+		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 *)ram_base; idx < ram_size / 4U; idx++) {
+		word_ptr[idx] = 0xFFFFFFFFUL;
+	}
+	for (idx = 0, word_ptr = (volatile uint32_t *)ram_base; idx < ram_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 *)ram_base; idx < ram_size / 4U; idx++) {
+		word_ptr[idx] = 0x0UL;
+	}
+	for (idx = 0, word_ptr = (volatile uint32_t *)ram_base; idx < ram_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;
+}

stm-firmware/boot/startup-tests.h

@@ -14,5 +14,12 @@
  */
 uint32_t startup_test_perform_ccm_ram_check(void);
 
+/**
+ * @brief Do a RAM check of the stnadard SRAM regions
+ * @return 0 if successful. If an error is found, the faulty address is returned
+ * @warning This completely destroys all content in the memory!
+ * @warning Ensure that the stack pointer is moved to a different memory reagion (CCM RAM)!
+ */
+uint32_t startup_test_perform_system_ram_check(void);
 
 #endif /* _STARTUP_TESTS_H_ */

stm-firmware/boot/startup_stm32f407vx.c

@@ -289,7 +289,7 @@ extern unsigned int __ld_eheap;
 
 #define CPACR (*((volatile uint32_t *)0xE000ED88))
 
-void Reset_Handler(void) {
+void __attribute__((noreturn)) Reset_Handler(void) {
 	/* Stack is already initialized by hardware */
 
 	/* The first thing we do here, is to initialize the FPU
@@ -298,10 +298,9 @@ 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?) */
+	 * Prepare RAM etc for the System Init function. This ensures, the RAM tests execute at max speed.
-		while (1);
+	 */
-	}
 
 	/* Copy .data section */
 	__init_section(&__ld_load_data, &__ld_sdata, &__ld_edata);
@@ -317,6 +316,41 @@ void Reset_Handler(void) {
 	/* Set clocks, waitstates, ART operation etc. */
 	SystemInit();
 
+	if (startup_test_perform_ccm_ram_check()) {
+		/* Hang forever in case of an error. We cannot handle this (yet?) */
+		while (1);
+	}
+
+	/* Move the Stack pointer to CCMRAM
+	 * This allows us to perform a RAM test on the main RAM.
+	 * Note: sp is not required to be inside the clobber list!
+	 */
+	__asm__ __volatile__ ("mov sp, %0\n\t" :: "r"(0x10000000UL + (64U * 1024UL)) :);
+
+	if (startup_test_perform_system_ram_check()) {
+		while (1);
+	}
+
+	/* Move the stack pointer back. Note: This only works if this function does not use the stack for variables.
+	 * Otherwise everything will be broken.
+	 */
+	__asm__ __volatile__ ("mov sp, %0\n\t" :: "r"(&__ld_top_of_stack) :);
+
+	/**
+	 * RAM tests destroyed our values. So we have to copy them again...
+	 */
+
+	/* Copy .data section */
+	__init_section(&__ld_load_data, &__ld_sdata, &__ld_edata);
+	/* Fill bss with zero */
+	__fill_zero(&__ld_sbss, &__ld_ebss);
+	/* Fill Heap with zero */
+	__fill_zero(&__ld_sheap, &__ld_eheap);
+	/* Fill static CCM memory with zeroes */
+	__fill_zero(&__ld_sbss_ccm, &__ld_ebss_ccm);
+	/* Init CCM RAM data section */
+	__init_section(&__ld_load_ccm_data, &__ld_sdata_ccm, &__ld_edata_ccm);
+	
 	/* C++ init function */
 #if defined(__cplusplus)
 	__libc_init_array();