/* 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 #include /** * @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. */ #if defined ( __CC_ARM ) __asm static void bootloader_util_reset(uint32_t start_addr) { LDR R5, [R0] ; Get App initial MSP for bootloader. MSR MSP, R5 ; Set the main stack pointer to the applications MSP. LDR R0, [R0, #0x04] ; Load Reset handler into R0. This will be first argument to branch instruction (BX). MOVS R4, #0xFF ; Load ones to R4. SXTB R4, R4 ; Sign extend R4 to obtain 0xFFFFFFFF instead of 0xFF. MRS R5, IPSR ; Load IPSR to R5 to check for handler or thread mode. CMP R5, #0x00 ; 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. MOV LR, R4 ; Clear the link register and set to ones to ensure no return, R4 = 0xFFFFFFFF. BX R0 ; Branch to reset handler of bootloader. isr_abort ; R4 contains ones from line above. Will be popped as R12 when exiting ISR (Cleaning up the registers). MOV R5, R4 ; 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. MOVS r7, #0x21 ; Move MSB reset value of xPSR to R7. Will be popped as xPSR when exiting ISR. xPSR is 0x21000000 thus MSB is 0x21. REV r7, r7 ; Reverse byte order to put 0x21 as MSB. PUSH {r4-r7} ; Push everything to new stack to allow interrupt handler to fetch it on exiting the ISR. MOVS R4, #0x00 ; Fill with zeros before jumping to reset handling. We be popped as R0 when exiting ISR (Cleaning up of the registers). MOVS R5, #0x00 ; Fill with zeros before jumping to reset handling. We be popped as R1 when exiting ISR (Cleaning up of the registers). MOVS R6, #0x00 ; Fill with zeros before jumping to reset handling. We be popped as R2 when exiting ISR (Cleaning up of the registers). MOVS R7, #0x00 ; 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. MOVS R0, #0xF9 ; Move the execution return command into register, 0xFFFFFFF9. SXTB R0, R0 ; Sign extend R0 to obtain 0xFFFFFFF9 instead of 0xF9. BX R0 ; No return - Handler mode will be exited. Stack will be popped and execution will continue in reset handler initializing other application. ALIGN } #elif defined ( __GNUC__ ) static inline void bootloader_util_reset(uint32_t start_addr) { __asm volatile( "ldr r0, [%0]\t\n" // Get App initial MSP for bootloader. "msr msp, r0\t\n" // Set the main stack pointer to the applications MSP. "ldr r0, [%0, #0x04]\t\n" // Load Reset handler into R0. "movs r4, #0xFF\t\n" // Move ones to R4. "sxtb r4, r4\t\n" // Sign extend R4 to obtain 0xFFFFFFFF instead of 0xFF. "mrs r5, IPSR\t\n" // Load IPSR to R5 to check for handler or thread mode. "cmp r5, #0x00\t\n" // Compare, if 0 then we are in thread mode and can continue to reset handler of bootloader. "bne isr_abort\t\n" // If not zero we need to exit current ISR and jump to reset handler of bootloader. "mov lr, r4\t\n" // Clear the link register and set to ones to ensure no return. "bx r0\t\n" // Branch to reset handler of bootloader. "isr_abort: \t\n" "mov r5, r4\t\n" // Fill with ones before jumping to reset handling. Will be popped as LR when exiting ISR. Ensures no return to application. "mov r6, r0\t\n" // 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. "movs r7, #0x21\t\n" // Move MSB reset value of xPSR to R7. Will be popped as xPSR when exiting ISR. xPSR is 0x21000000 thus MSB is 0x21. "rev r7, r7\t\n" // Reverse byte order to put 0x21 as MSB. "push {r4-r7}\t\n" // Push everything to new stack to allow interrupt handler to fetch it on exiting the ISR. "movs r4, #0x00\t\n" // Fill with zeros before jumping to reset handling. We be popped as R0 when exiting ISR (Cleaning up of the registers). "movs r5, #0x00\t\n" // Fill with zeros before jumping to reset handling. We be popped as R1 when exiting ISR (Cleaning up of the registers). "movs r6, #0x00\t\n" // Fill with zeros before jumping to reset handling. We be popped as R2 when exiting ISR (Cleaning up of the registers). "movs r7, #0x00\t\n" // Fill with zeros before jumping to reset handling. We be popped as R3 when exiting ISR (Cleaning up of the registers). "push {r4-r7}\t\n" // Push zeros (R4-R7) to stack to prepare for exiting the interrupt routine. "movs r0, #0xF9\t\n" // Move the execution return command into register, 0xFFFFFFF9. "sxtb r0, r0\t\n" // Sign extend R0 to obtain 0xFFFFFFF9 instead of 0xF9. "bx r0\t\n" // No return - Handler mode will be exited. Stack will be popped and execution will continue in reset handler initializing other application. ".align\t\n" :: "r" (start_addr) // Argument list for the gcc assembly. start_addr is %0. : "r0", "r4", "r5", "r6", "r7" // List of register maintained manually. ); } #elif defined ( __ICCARM__ ) static inline void bootloader_util_reset(uint32_t start_addr) { asm("ldr r5, [%0]\n" // Get App initial MSP for bootloader. "msr msp, r5\n" // Set the main stack pointer to the applications MSP. "ldr r0, [%0, #0x04]\n" // Load Reset handler into R0. "movs r4, #0x00\n" // Load zero into R4. "mvns r4, r4\n" // Invert R4 to ensure it contain ones. "mrs r5, IPSR\n" // Load IPSR to R5 to check for handler or thread mode "cmp r5, #0x00\n" // Compare, if 0 then we are in thread mode and can continue to reset handler of bootloader. "bne.n isr_abort\n" // If not zero we need to exit current ISR and jump to reset handler of bootloader. "mov lr, r4\n" // Clear the link register and set to ones to ensure no return. "bx r0\n" // Branch to reset handler of bootloader. "isr_abort: \n" // R4 contains ones from line above. We be popped as R12 when exiting ISR (Cleaning up the registers). "mov r5, r4\n" // Fill with ones before jumping to reset handling. Will be popped as LR when exiting ISR. Ensures no return to application. "mov r6, r0\n" // 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. "movs r7, #0x21\n" // Move MSB reset value of xPSR to R7. Will be popped as xPSR when exiting ISR. xPSR is 0x21000000 thus MSB is 0x21. "rev r7, r7\n" // Reverse byte order to put 0x21 as MSB. "push {r4-r7}\n" // Push everything to new stack to allow interrupt handler to fetch it on exiting the ISR. "movs r4, #0x00\n" // Fill with zeros before jumping to reset handling. We be popped as R0 when exiting ISR (Cleaning up of the registers). "movs r5, #0x00\n" // Fill with zeros before jumping to reset handling. We be popped as R1 when exiting ISR (Cleaning up of the registers). "movs r6, #0x00\n" // Fill with zeros before jumping to reset handling. We be popped as R2 when exiting ISR (Cleaning up of the registers). "movs r7, #0x00\n" // Fill with zeros before jumping to reset handling. We be popped as R3 when exiting ISR (Cleaning up of the registers). "push {r4-r7}\n" // Push zeros (R4-R7) to stack to prepare for exiting the interrupt routine. "movs r0, #0x06\n" // Load 0x06 into R6 to prepare for exec return command. "mvns r0, r0\n" // Invert 0x06 to obtain EXEC_RETURN, 0xFFFFFFF9. "bx r0\n" // No return - Handler mode will be exited. Stack will be popped and execution will continue in reset handler initializing other application. :: "r" (start_addr) // Argument list for the IAR assembly. start_addr is %0. : "r0", "r4", "r5", "r6", "r7"); // List of register maintained manually. } #else #error Compiler not supported. #endif void bootloader_util_app_start(uint32_t start_addr) { bootloader_util_reset(start_addr); }