| 1 | /*********************************************************************
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| 2 | * SEGGER Microcontroller GmbH *
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| 3 | * The Embedded Experts *
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| 4 | **********************************************************************
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| 5 | * *
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| 6 | * (c) 2014 - 2024 SEGGER Microcontroller GmbH *
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| 7 | * *
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| 8 | * www.segger.com Support: support@segger.com *
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| 9 | * *
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| 10 | **********************************************************************
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| 11 | * *
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| 12 | * All rights reserved. *
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| 13 | * *
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| 14 | * Redistribution and use in source and binary forms, with or *
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| 15 | * without modification, are permitted provided that the following *
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| 16 | * condition is met: *
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| 17 | * *
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| 18 | * - Redistributions of source code must retain the above copyright *
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| 19 | * notice, this condition and the following disclaimer. *
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| 20 | * *
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| 21 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND *
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| 22 | * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, *
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| 23 | * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF *
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| 24 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE *
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| 25 | * DISCLAIMED. IN NO EVENT SHALL SEGGER Microcontroller BE LIABLE FOR *
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| 26 | * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR *
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| 27 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT *
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| 28 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; *
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| 29 | * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF *
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| 30 | * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT *
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| 31 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE *
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| 32 | * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH *
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| 33 | * DAMAGE. *
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| 34 | * *
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| 35 | **********************************************************************
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| 36 |
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| 37 | -------------------------- END-OF-HEADER -----------------------------
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| 38 |
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| 39 | File : STM32G4xx_Startup.s
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| 40 | Purpose : Startup and exception handlers for STM32G4xx devices.
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| 41 |
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| 42 | Additional information:
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| 43 | Preprocessor Definitions
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| 44 | __NO_SYSTEM_INIT
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| 45 | If defined,
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| 46 | SystemInit is not called.
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| 47 | If not defined,
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| 48 | SystemInit is called.
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| 49 | SystemInit is usually supplied by the CMSIS files.
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| 50 | This file declares a weak implementation as fallback.
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| 51 |
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| 52 | __NO_SYSTEM_CLK_UPDATE
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| 53 | If defined,
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| 54 | SystemCoreClockUpdate is not automatically called.
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| 55 | Should be defined if SystemCoreClockUpdate must not be called before main().
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| 56 | If not defined,
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| 57 | SystemCoreClockUpdate is called before the application entry point.
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| 58 |
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| 59 | __MEMORY_INIT
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| 60 | If defined,
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| 61 | MemoryInit is called after SystemInit.
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| 62 | void MemoryInit(void) can be implemented to enable external
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| 63 | memory controllers.
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| 64 |
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| 65 | __VECTORS_IN_RAM
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| 66 | If defined,
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| 67 | the vector table will be copied from Flash to RAM,
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| 68 | and the vector table offset register is adjusted.
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| 69 |
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| 70 | __VTOR_CONFIG
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| 71 | If defined,
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| 72 | the vector table offset register is set to point to the
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| 73 | application's vector table.
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| 74 |
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| 75 | __NO_FPU_ENABLE
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| 76 | If defined, the FPU is explicitly not enabled,
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| 77 | even if the compiler could use floating point operations.
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| 78 |
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| 79 | __SOFTFP__
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| 80 | Defined by the build system.
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| 81 | If not defined, the FPU is enabled for floating point operations.
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| 82 | */
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| 83 |
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| 84 | .syntax unified
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| 85 |
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| 86 |
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| 87 | /*********************************************************************
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| 88 | *
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| 89 | * Global functions
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| 90 | *
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| 91 | **********************************************************************
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| 92 | */
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| 93 | /*********************************************************************
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| 94 | *
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| 95 | * Reset_Handler
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| 96 | *
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| 97 | * Function description
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| 98 | * Exception handler for reset.
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| 99 | * Generic bringup of a Cortex-M system.
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| 100 | *
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| 101 | * Additional information
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| 102 | * The stack pointer is expected to be initialized by hardware,
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| 103 | * i.e. read from vectortable[0].
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| 104 | * For manual initialization add
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| 105 | * ldr R0, =__stack_end__
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| 106 | * mov SP, R0
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| 107 | */
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| 108 | .global reset_handler
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| 109 | .global Reset_Handler
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| 110 | .equ reset_handler, Reset_Handler
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| 111 | .section .init.Reset_Handler, "ax"
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| 112 | .balign 2
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| 113 | .thumb_func
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| 114 | Reset_Handler:
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| 115 | #ifdef __SEGGER_STOP
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| 116 | .extern __SEGGER_STOP_Limit_MSP
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| 117 | //
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| 118 | // Initialize main stack limit to 0 to disable stack checks before runtime init
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| 119 | //
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| 120 | movs R0, #0
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| 121 | ldr R1, =__SEGGER_STOP_Limit_MSP
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| 122 | str R0, [R1]
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| 123 | #endif
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| 124 | #ifndef __NO_SYSTEM_INIT
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| 125 | //
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| 126 | // Call SystemInit
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| 127 | //
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| 128 | bl SystemInit
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| 129 | #endif
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| 130 | #ifdef __MEMORY_INIT
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| 131 | //
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| 132 | // Call MemoryInit
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| 133 | //
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| 134 | //bl MemoryInit
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| 135 | ldr r1, =0x20000000 // start address of SRAM
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| 136 | ldr r2, =0x20008000 // end address of SRAM
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| 137 | movs r3, #0 // we want to write 0 to all address
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| 138 | SRAM1:
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| 139 | str r3, [r1] // store 0 at address
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| 140 | adds r1, r1, #4 // increment to next address
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| 141 | cmp r1, r2 // update flags
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| 142 | bne SRAM1 // branch if write address equals end of SRAM
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| 143 |
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| 144 | ldr r1, =0x20018000 // start address of CCM-SRAM
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| 145 | ldr r2, =0x20020000 // end address of CCM-SRAM
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| 146 | movs r3, #0 // we want to write 0 to all address
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| 147 | CCM_SRAM:
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| 148 | str r3, [r1] // store 0 at address
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| 149 | adds r1, r1, #4 // increment to next address
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| 150 | cmp r1, r2 // update flags
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| 151 | bne CCM_SRAM // branch if write address equals end of CCM-SRAM
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| 152 |
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| 153 | #endif
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| 154 | #ifdef __VECTORS_IN_RAM
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| 155 | //
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| 156 | // Copy vector table (from Flash) to RAM
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| 157 | //
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| 158 | ldr R0, =__vectors_start__
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| 159 | ldr R1, =__vectors_end__
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| 160 | ldr R2, =__vectors_ram_start__
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| 161 | 1:
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| 162 | cmp R0, R1
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| 163 | beq 2f
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| 164 | ldr R3, [R0]
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| 165 | str R3, [R2]
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| 166 | adds R0, R0, #4
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| 167 | adds R2, R2, #4
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| 168 | b 1b
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| 169 | 2:
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| 170 | #endif
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| 171 |
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| 172 | #if defined(__VTOR_CONFIG) || defined(__VECTORS_IN_RAM)
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| 173 | //
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| 174 | // Configure vector table offset register
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| 175 | //
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| 176 | #ifdef __ARM_ARCH_6M__
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| 177 | ldr R0, =0xE000ED08 // VTOR_REG
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| 178 | #else
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| 179 | movw R0, 0xED08 // VTOR_REG
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| 180 | movt R0, 0xE000
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| 181 | #endif
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| 182 | #ifdef __VECTORS_IN_RAM
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| 183 | ldr R1, =_vectors_ram
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| 184 | #else
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| 185 | ldr R1, =_vectors
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| 186 | #endif
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| 187 | str R1, [R0]
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| 188 | #endif
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| 189 | #if !defined(__SOFTFP__) && !defined(__NO_FPU_ENABLE)
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| 190 | //
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| 191 | // Enable CP11 and CP10 with CPACR |= (0xf<<20)
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| 192 | //
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| 193 | movw R0, 0xED88 // CPACR
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| 194 | movt R0, 0xE000
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| 195 | ldr R1, [R0]
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| 196 | orrs R1, R1, #(0xf << 20)
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| 197 | str R1, [R0]
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| 198 | #endif
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| 199 | //
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| 200 | // Call runtime initialization, which calls main().
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| 201 | //
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| 202 | bl _start
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| 203 |
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| 204 | //
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| 205 | // Weak only declaration of SystemInit enables Linker to replace bl SystemInit with a NOP,
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| 206 | // when there is no strong definition of SystemInit.
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| 207 | //
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| 208 | .weak SystemInit
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| 209 | //
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| 210 | // Place SystemCoreClockUpdate in .init_array
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| 211 | // to be called after runtime initialization
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| 212 | //
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| 213 | #if !defined(__NO_SYSTEM_INIT) && !defined(__NO_SYSTEM_CLK_UPDATE)
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| 214 | .section .init_array, "aw"
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| 215 | .balign 4
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| 216 | .word SystemCoreClockUpdate
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| 217 | #endif
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| 218 |
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| 219 | /*********************************************************************
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| 220 | *
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| 221 | * HardFault_Handler
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| 222 | *
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| 223 | * Function description
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| 224 | * Simple exception handler for HardFault.
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| 225 | * In case of a HardFault caused by BKPT instruction without
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| 226 | * debugger attached, return execution, otherwise stay in loop.
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| 227 | *
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| 228 | * Additional information
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| 229 | * The stack pointer is expected to be initialized by hardware,
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| 230 | * i.e. read from vectortable[0].
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| 231 | * For manual initialization add
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| 232 | * ldr R0, =__stack_end__
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| 233 | * mov SP, R0
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| 234 | */
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| 235 |
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| 236 | #undef L
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| 237 | #define L(label) .LHardFault_Handler_##label
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| 238 |
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| 239 | .weak HardFault_Handler
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| 240 | .section .init.HardFault_Handler, "ax"
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| 241 | .balign 2
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| 242 | .thumb_func
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| 243 | HardFault_Handler:
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| 244 | //
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| 245 | // Check if HardFault is caused by BKPT instruction
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| 246 | //
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| 247 | ldr R1, =0xE000ED2C // Load NVIC_HFSR
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| 248 | ldr R2, [R1]
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| 249 | cmp R2, #0 // Check NVIC_HFSR[31]
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| 250 |
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| 251 | L(hfLoop):
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| 252 | bmi L(hfLoop) // Not set? Stay in HardFault Handler.
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| 253 | //
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| 254 | // Continue execution after BKPT instruction
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| 255 | //
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| 256 | #if defined(__thumb__) && !defined(__thumb2__)
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| 257 | movs R0, #4
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| 258 | mov R1, LR
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| 259 | tst R0, R1 // Check EXC_RETURN in Link register bit 2.
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| 260 | bne L(Uses_PSP)
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| 261 | mrs R0, MSP // Stacking was using MSP.
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| 262 | b L(Pass_StackPtr)
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| 263 | L(Uses_PSP):
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| 264 | mrs R0, PSP // Stacking was using PSP.
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| 265 | L(Pass_StackPtr):
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| 266 | #else
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| 267 | tst LR, #4 // Check EXC_RETURN[2] in link register to get the return stack
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| 268 | ite eq
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| 269 | mrseq R0, MSP // Frame stored on MSP
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| 270 | mrsne R0, PSP // Frame stored on PSP
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| 271 | #endif
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| 272 | //
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| 273 | // Reset HardFault Status
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| 274 | //
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| 275 | #if defined(__thumb__) && !defined(__thumb2__)
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| 276 | movs R3, #1
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| 277 | lsls R3, R3, #31
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| 278 | orrs R2, R3
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| 279 | str R2, [R1]
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| 280 | #else
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| 281 | orr R2, R2, #0x80000000
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| 282 | str R2, [R1]
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| 283 | #endif
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| 284 | //
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| 285 | // Adjust return address
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| 286 | //
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| 287 | ldr R1, [R0, #24] // Get stored PC from stack
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| 288 | adds R1, #2 // Adjust PC by 2 to skip current BKPT
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| 289 | str R1, [R0, #24] // Write back adjusted PC to stack
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| 290 | //
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| 291 | bx LR // Return
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| 292 |
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| 293 | /*************************** End of file ****************************/
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