1 | /** |
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2 | * @file |
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3 | * |
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4 | * @brief Boot and system start code. |
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5 | */ |
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6 | |
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7 | /* |
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8 | * Copyright (c) 2008-2013 embedded brains GmbH. All rights reserved. |
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9 | * |
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10 | * embedded brains GmbH |
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11 | * Obere Lagerstr. 30 |
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12 | * 82178 Puchheim |
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13 | * Germany |
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14 | * <rtems@embedded-brains.de> |
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15 | * |
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16 | * The license and distribution terms for this file may be |
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17 | * found in the file LICENSE in this distribution or at |
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18 | * http://www.rtems.com/license/LICENSE. |
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19 | */ |
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20 | |
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21 | #include <rtems/asm.h> |
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22 | #include <rtems/system.h> |
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23 | #include <rtems/score/cpu.h> |
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24 | |
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25 | #include <bspopts.h> |
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26 | #include <bsp/irq.h> |
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27 | #include <bsp/linker-symbols.h> |
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28 | |
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29 | /* External symbols */ |
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30 | .extern bsp_reset |
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31 | .extern boot_card |
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32 | .extern bsp_start_hook_0 |
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33 | .extern bsp_start_hook_1 |
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34 | .extern _ARMV4_Exception_undef_default |
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35 | .extern _ARMV4_Exception_swi_default |
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36 | .extern _ARMV4_Exception_data_abort_default |
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37 | .extern _ARMV4_Exception_pref_abort_default |
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38 | .extern _ARMV4_Exception_reserved_default |
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39 | .extern _ARMV4_Exception_irq_default |
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40 | .extern _ARMV4_Exception_fiq_default |
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41 | .extern _ARMV7M_Exception_default |
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42 | |
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43 | /* Global symbols */ |
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44 | .globl _start |
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45 | .globl bsp_start_vector_table_begin |
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46 | .globl bsp_start_vector_table_end |
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47 | .globl bsp_start_vector_table_size |
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48 | .globl bsp_vector_table_size |
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49 | |
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50 | .section ".bsp_start_text", "ax" |
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51 | |
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52 | #if defined(ARM_MULTILIB_ARCH_V4) |
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53 | |
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54 | .arm |
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55 | |
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56 | /* |
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57 | * This is the exception vector table and the pointers to the default |
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58 | * exceptions handlers. |
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59 | */ |
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60 | |
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61 | bsp_start_vector_table_begin: |
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62 | |
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63 | ldr pc, handler_addr_reset |
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64 | ldr pc, handler_addr_undef |
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65 | ldr pc, handler_addr_swi |
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66 | ldr pc, handler_addr_prefetch |
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67 | ldr pc, handler_addr_abort |
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68 | |
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69 | /* Program signature checked by boot loader */ |
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70 | .word 0xb8a06f58 |
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71 | |
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72 | ldr pc, handler_addr_irq |
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73 | ldr pc, handler_addr_fiq |
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74 | |
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75 | handler_addr_reset: |
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76 | |
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77 | #ifdef BSP_START_RESET_VECTOR |
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78 | .word BSP_START_RESET_VECTOR |
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79 | #else |
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80 | .word _start |
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81 | #endif |
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82 | |
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83 | handler_addr_undef: |
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84 | |
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85 | .word _ARMV4_Exception_undef_default |
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86 | |
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87 | handler_addr_swi: |
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88 | |
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89 | .word _ARMV4_Exception_swi_default |
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90 | |
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91 | handler_addr_prefetch: |
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92 | |
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93 | .word _ARMV4_Exception_data_abort_default |
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94 | |
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95 | handler_addr_abort: |
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96 | |
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97 | .word _ARMV4_Exception_pref_abort_default |
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98 | |
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99 | handler_addr_reserved: |
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100 | |
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101 | .word _ARMV4_Exception_reserved_default |
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102 | |
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103 | handler_addr_irq: |
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104 | |
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105 | .word _ARMV4_Exception_irq_default |
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106 | |
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107 | handler_addr_fiq: |
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108 | |
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109 | .word _ARMV4_Exception_fiq_default |
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110 | |
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111 | bsp_start_vector_table_end: |
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112 | |
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113 | /* Start entry */ |
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114 | |
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115 | _start: |
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116 | |
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117 | /* |
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118 | * We do not save the context since we do not return to the boot |
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119 | * loader. |
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120 | */ |
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121 | |
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122 | /* |
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123 | * Set SVC mode, disable interrupts and enable ARM instructions. |
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124 | */ |
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125 | mov r0, #(ARM_PSR_M_SVC | ARM_PSR_I | ARM_PSR_F) |
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126 | msr cpsr, r0 |
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127 | |
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128 | /* Initialize stack pointer registers for the various modes */ |
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129 | |
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130 | /* Enter IRQ mode and set up the IRQ stack pointer */ |
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131 | mov r0, #(ARM_PSR_M_IRQ | ARM_PSR_I | ARM_PSR_F) |
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132 | msr cpsr, r0 |
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133 | ldr sp, =bsp_stack_irq_end |
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134 | |
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135 | /* Enter FIQ mode and set up the FIQ stack pointer */ |
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136 | mov r0, #(ARM_PSR_M_FIQ | ARM_PSR_I | ARM_PSR_F) |
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137 | msr cpsr, r0 |
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138 | ldr sp, =bsp_stack_fiq_end |
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139 | |
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140 | /* Enter ABT mode and set up the ABT stack pointer */ |
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141 | mov r0, #(ARM_PSR_M_ABT | ARM_PSR_I | ARM_PSR_F) |
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142 | msr cpsr, r0 |
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143 | ldr sp, =bsp_stack_abt_end |
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144 | |
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145 | /* Enter UND mode and set up the UND stack pointer */ |
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146 | mov r0, #(ARM_PSR_M_UND | ARM_PSR_I | ARM_PSR_F) |
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147 | msr cpsr, r0 |
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148 | ldr sp, =bsp_stack_und_end |
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149 | |
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150 | /* Enter SVC mode and set up the SVC stack pointer */ |
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151 | mov r0, #(ARM_PSR_M_SVC | ARM_PSR_I | ARM_PSR_F) |
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152 | msr cpsr, r0 |
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153 | ldr sp, =bsp_stack_svc_end |
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154 | |
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155 | /* Stay in SVC mode */ |
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156 | |
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157 | #ifdef ARM_MULTILIB_VFP_D32 |
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158 | /* Read CPACR */ |
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159 | mrc p15, 0, r0, c1, c0, 2 |
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160 | |
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161 | /* Enable CP10 and CP11 */ |
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162 | orr r0, r0, #(1 << 20) |
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163 | orr r0, r0, #(1 << 22) |
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164 | |
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165 | /* Clear ASEDIS and D32DIS */ |
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166 | bic r0, r0, #(3 << 30) |
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167 | |
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168 | /* Write CPACR */ |
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169 | mcr p15, 0, r0, c1, c0, 2 |
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170 | isb |
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171 | |
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172 | /* Enable FPU */ |
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173 | mov r0, #(1 << 30) |
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174 | vmsr FPEXC, r0 |
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175 | #endif |
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176 | |
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177 | /* |
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178 | * Branch to start hook 0. |
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179 | * |
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180 | * The previous code and parts of the start hook 0 may run with an |
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181 | * address offset. This implies that only branches relative to the |
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182 | * program counter are allowed. After the start hook 0 it is assumed |
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183 | * that the code can run at its intended position. Thus the link |
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184 | * register will be loaded with the absolute address. In THUMB mode |
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185 | * the start hook 0 must be within a 2kByte range due to the branch |
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186 | * instruction limitation. |
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187 | */ |
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188 | |
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189 | ldr lr, =bsp_start_hook_0_done |
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190 | #ifdef __thumb__ |
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191 | orr lr, #1 |
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192 | #endif |
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193 | |
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194 | SWITCH_FROM_ARM_TO_THUMB r0 |
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195 | |
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196 | b bsp_start_hook_0 |
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197 | |
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198 | bsp_start_hook_0_done: |
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199 | |
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200 | SWITCH_FROM_THUMB_TO_ARM |
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201 | |
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202 | /* |
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203 | * Initialize the exception vectors. This includes the exceptions |
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204 | * vectors and the pointers to the default exception handlers. |
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205 | */ |
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206 | |
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207 | ldr r0, =bsp_vector_table_begin |
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208 | adr r1, bsp_start_vector_table_begin |
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209 | cmp r0, r1 |
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210 | beq bsp_vector_table_copy_done |
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211 | ldmia r1!, {r2-r9} |
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212 | stmia r0!, {r2-r9} |
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213 | ldmia r1!, {r2-r9} |
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214 | stmia r0!, {r2-r9} |
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215 | |
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216 | bsp_vector_table_copy_done: |
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217 | |
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218 | SWITCH_FROM_ARM_TO_THUMB r0 |
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219 | |
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220 | /* Branch to start hook 1 */ |
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221 | bl bsp_start_hook_1 |
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222 | |
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223 | /* Branch to boot card */ |
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224 | mov r0, #0 |
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225 | bl boot_card |
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226 | |
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227 | twiddle: |
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228 | |
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229 | /* Branch to reset function */ |
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230 | bl bsp_reset |
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231 | |
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232 | b twiddle |
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233 | |
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234 | #elif defined(ARM_MULTILIB_ARCH_V7M) |
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235 | |
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236 | .syntax unified |
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237 | |
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238 | .extern bsp_stack_main_end |
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239 | |
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240 | .thumb |
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241 | |
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242 | bsp_start_vector_table_begin: |
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243 | |
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244 | .word bsp_stack_main_end |
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245 | .word _start /* Reset */ |
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246 | .word _ARMV7M_Exception_default /* NMI */ |
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247 | .word _ARMV7M_Exception_default /* Hard Fault */ |
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248 | .word _ARMV7M_Exception_default /* MPU Fault */ |
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249 | .word _ARMV7M_Exception_default /* Bus Fault */ |
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250 | .word _ARMV7M_Exception_default /* Usage Fault */ |
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251 | .word _ARMV7M_Exception_default /* Reserved */ |
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252 | .word _ARMV7M_Exception_default /* Reserved */ |
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253 | .word _ARMV7M_Exception_default /* Reserved */ |
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254 | .word _ARMV7M_Exception_default /* Reserved */ |
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255 | .word _ARMV7M_Exception_default /* SVC */ |
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256 | .word _ARMV7M_Exception_default /* Debug Monitor */ |
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257 | .word _ARMV7M_Exception_default /* Reserved */ |
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258 | .word _ARMV7M_Exception_default /* PendSV */ |
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259 | .word _ARMV7M_Exception_default /* SysTick */ |
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260 | .rept BSP_INTERRUPT_VECTOR_MAX + 1 |
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261 | .word _ARMV7M_Exception_default /* IRQ */ |
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262 | .endr |
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263 | |
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264 | bsp_start_vector_table_end: |
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265 | |
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266 | .thumb_func |
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267 | |
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268 | _start: |
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269 | |
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270 | ldr sp, =bsp_stack_main_end |
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271 | ldr lr, =bsp_start_hook_0_done + 1 |
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272 | b bsp_start_hook_0 |
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273 | |
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274 | bsp_start_hook_0_done: |
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275 | |
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276 | bl bsp_start_hook_1 |
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277 | movs r0, #0 |
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278 | bl boot_card |
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279 | |
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280 | twiddle: |
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281 | |
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282 | bl bsp_reset |
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283 | b twiddle |
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284 | |
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285 | #endif /* defined(ARM_MULTILIB_ARCH_V7M) */ |
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286 | |
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287 | .set bsp_start_vector_table_size, bsp_start_vector_table_end - bsp_start_vector_table_begin |
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288 | .set bsp_vector_table_size, bsp_start_vector_table_size |
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