From 9cfdf6e379809690dde08f45a1e9b45e4a2c80c3 Mon Sep 17 00:00:00 2001
From: Kaspar Schleiser <kaspar@schleiser.de>
Date: Thu, 5 Oct 2017 17:13:11 +0200
Subject: [PATCH] cpu/cortexm_common: introduce cpu_jump_to_image()
This new function allows to jump to another execution
environment (VTOR) located at a certain (aligned) address.
It's used to boot firmwares at another location than
`CPU_FLASH_BASE`.
The user needs to ensure that the CPU using this feature
is able to be initialised at least twice while jumping
to the RIOT `reset_handler_default` function, since it
initialises the CPU again (calls cpu_init()).
Co-authored-by: Kaspar Schleiser <kaspar@schleiser.de>
---
cpu/cortexm_common/include/cpu.h | 38 ++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/cpu/cortexm_common/include/cpu.h b/cpu/cortexm_common/include/cpu.h
index 50ba3b3e12..aa1364c492 100644
--- a/cpu/cortexm_common/include/cpu.h
+++ b/cpu/cortexm_common/include/cpu.h
@@ -189,6 +189,44 @@ static inline void cortexm_isr_end(void)
}
}
+/**
+ * @brief Jumps to another image in flash
+ *
+ * This function is supposed to be called by a bootloader application.
+ *
+ * @param[in] image_address address in flash of other image
+ */
+static inline void cpu_jump_to_image(uint32_t image_address)
+{
+ /* Disable IRQ */
+ __disable_irq();
+
+ /* set MSP */
+ __set_MSP(*(uint32_t*)image_address);
+
+ /* skip stack pointer */
+ image_address += 4;
+
+ /* load the images reset_vector address */
+ uint32_t destination_address = *(uint32_t*)image_address;
+
+ /* Make sure the Thumb State bit is set. */
+ destination_address |= 0x1;
+
+ /* Branch execution */
+ __asm("BX %0" :: "r" (destination_address));
+}
+
+/* The following register is only present for Cortex-M0+, -M3, -M4 and -M7 CPUs */
+#if defined(CPU_ARCH_CORTEX_M0PLUS) || defined(CPU_ARCH_CORTEX_M3) || \
+ defined(CPU_ARCH_CORTEX_M4) || defined(CPU_ARCH_CORTEX_M4F) || \
+ defined(CPU_ARCH_CORTEX_M7)
+static inline uint32_t cpu_get_image_baseaddr(void)
+{
+ return SCB->VTOR;
+}
+#endif
+
#ifdef __cplusplus
}
#endif
--
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