Diff: nordic/bootloader_dfu/bootloader_util_arm.c

Revision:

66:b3680699d9a4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nordic/bootloader_dfu/bootloader_util_arm.c	Mon Sep 22 11:19:51 2014 +0100
@@ -0,0 +1,91 @@
+/* Copyright (c) 2013 Nordic Semiconductor. All Rights Reserved.
+ *
+ * The information contained herein is property of Nordic Semiconductor ASA.
+ * Terms and conditions of usage are described in detail in NORDIC
+ * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
+ *
+ * Licensees are granted free, non-transferable use of the information. NO
+ * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
+ * the file.
+ *
+ */
+
+#include "bootloader_util.h"
+#include <stdint.h>
+
+
+/**
+ * @brief Function for aborting current handler mode and jump to to other application/bootloader.
+ *
+ * @details This functions will use the address provide (reset handler) to be executed after 
+ *          handler mode is exited. It creates an initial stack to ensure correct reset behavior 
+ *          when the reset handler is executed.
+ *
+ * @param[in]  reset_handler  Address of the reset handler to be executed when handler mode exits.
+ *
+ * @note This function must never be called directly from 'C' but is intended only to be used from 
+ *       \ref bootloader_util_reset. This function will never return but issue a reset into 
+ *       provided address.
+ */
+__asm void isr_abort(uint32_t reset_handler)
+{
+xPSR_RESET      EQU 0x21000000  ; Default value of xPSR after System Reset.
+EXC_RETURN_CMD  EQU 0xFFFFFFF9  ; EXC_RETURN for ARM Cortex. When loaded to PC the current interrupt service routine (handler mode) willl exit and the stack will be popped. Execution will continue in thread mode.
+
+    LDR   R4,=MASK_ONES         ; Fill with ones before jumping to reset handling. We be popped as R12 when exiting ISR (Cleaning up the registers).
+    LDR   R5,=MASK_ONES         ; Fill with ones before jumping to reset handling. We be popped as LR when exiting ISR. Ensures no return to application.
+    MOV   R6, R0                ; Move address of reset handler to R6. Will be popped as PC when exiting ISR. Ensures the reset handler will be executed when exist ISR.
+    LDR   R7,=xPSR_RESET        ; Move reset value of xPSR to R7. Will be popped as xPSR when exiting ISR.
+    PUSH  {r4-r7}               ; Push everything to new stack to allow interrupt handler to fetch it on exiting the ISR.
+    
+    LDR   R4,=MASK_ZEROS        ; Fill with zeros before jumping to reset handling. We be popped as R0 when exiting ISR (Cleaning up of the registers).
+    LDR   R5,=MASK_ZEROS        ; Fill with zeros before jumping to reset handling. We be popped as R1 when exiting ISR (Cleaning up of the registers).
+    LDR   R6,=MASK_ZEROS        ; Fill with zeros before jumping to reset handling. We be popped as R2 when exiting ISR (Cleaning up of the registers).
+    LDR   R7,=MASK_ZEROS        ; Fill with zeros before jumping to reset handling. We be popped as R3 when exiting ISR (Cleaning up of the registers).
+    PUSH  {r4-r7}               ; Push zeros (R4-R7) to stack to prepare for exiting the interrupt routine.
+    
+    LDR   R0,=EXC_RETURN_CMD    ; Load the execution return command into register.
+    BX    R0                    ; No return - Handler mode will be exited. Stack will be popped and execution will continue in reset handler initializing other application.
+    ALIGN
+}
+
+
+/**
+ * @brief Function for aborting current application/bootloader jump to to other app/bootloader.
+ *
+ * @details This functions will use the address provide to swap the stack pointer and then load 
+ *          the address of the reset handler to be executed. It will check current system mode 
+ *          (thread/handler) and if in thread mode it will reset into other application.
+ *          If in handler mode \ref isr_abort will be executed to ensure correct exit of handler 
+ *          mode and jump into reset handler of other application.
+ *
+ * @param[in]  start_addr  Start address of other application. This address must point to the 
+               initial stack pointer of the application.
+ *
+ * @note This function will never return but issue a reset into provided application.
+ */
+__asm static void bootloader_util_reset(uint32_t start_addr)
+{
+MASK_ONES       EQU 0xFFFFFFFF  ; Ones, to be loaded into register as default value before reset.
+MASK_ZEROS      EQU 0x00000000  ; Zeros, to be loaded into register as default value before reset.
+
+    LDR   R1, [R0]              ; Get App initial MSP for bootloader.
+    MSR   MSP, R1               ; Set the main stack pointer to the applications MSP.
+    LDR   R0,[R0, #0x04]        ; Load Reset handler into register 0.
+    
+    LDR   R2, =MASK_ZEROS       ; Load zeros to R2
+    MRS   R3, IPSR              ; Load IPSR to R3 to check for handler or thread mode 
+    CMP   R2, R3                ; Compare, if 0 then we are in thread mode and can continue to reset handler of bootloader
+    BNE   isr_abort             ; If not zero we need to exit current ISR and jump to reset handler of bootloader
+
+    LDR   R4, =MASK_ONES        ; Load ones to R4 to be placed in Link Register.
+    MOV   LR, R4                ; Clear the link register and set to ones to ensure no return.
+    BX    R0                    ; Branch to reset handler of bootloader
+    ALIGN
+}
+
+
+void bootloader_util_app_start(uint32_t start_addr)
+{
+    bootloader_util_reset(start_addr);
+}