git.sur5r.net Git - freertos/blob - FreeRTOS/Source/portable/GCC/RISC-V-RV32/port.c

   1 /*\r
   2  * FreeRTOS Kernel V10.1.1\r
   3  * Copyright (C) 2018 Amazon.com, Inc. or its affiliates.  All Rights Reserved.\r
   4  *\r
   5  * Permission is hereby granted, free of charge, to any person obtaining a copy of\r
   6  * this software and associated documentation files (the "Software"), to deal in\r
   7  * the Software without restriction, including without limitation the rights to\r
   8  * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of\r
   9  * the Software, and to permit persons to whom the Software is furnished to do so,\r
  10  * subject to the following conditions:\r
  11  *\r
  12  * The above copyright notice and this permission notice shall be included in all\r
  13  * copies or substantial portions of the Software.\r
  14  *\r
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR\r
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS\r
  17  * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR\r
  18  * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER\r
  19  * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN\r
  20  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.\r
  21  *\r
  22  * http://www.FreeRTOS.org\r
  23  * http://aws.amazon.com/freertos\r
  24  *\r
  25  * 1 tab == 4 spaces!\r
  26  */\r
  27 \r
  28 /*-----------------------------------------------------------\r
  29  * Implementation of functions defined in portable.h for the RISC-V RV32 port.\r
  30  *----------------------------------------------------------*/\r
  31 \r
  32 /* Scheduler includes. */\r
  33 #include "FreeRTOS.h"\r
  34 #include "task.h"\r
  35 #include "portmacro.h"\r
  36 \r
  37 #ifdef configISR_STACK_SIZE\r
  38         /* The stack used by interrupt service routines. */\r
  39         static __attribute__ ((aligned(16))) StackType_t xISRStack[ configISR_STACK_SIZE ] = { 0 };\r
  40         const StackType_t * const xISRStackTop = &( xISRStack[ ( configISR_STACK_SIZE & ~portBYTE_ALIGNMENT_MASK ) - 1 ] );\r
  41 #else\r
  42 #warning What should _sp be named?\r
  43         extern const uint32_t _sp[];\r
  44         const uint32_t xISRStackTop = ( uint32_t ) _sp;\r
  45 #endif\r
  46 \r
  47 /*\r
  48  * Setup the timer to generate the tick interrupts.  The implementation in this\r
  49  * file is weak to allow application writers to change the timer used to\r
  50  * generate the tick interrupt.\r
  51  */\r
  52 void vPortSetupTimerInterrupt( void ) __attribute__(( weak ));\r
  53 \r
  54 /*\r
  55  * Used to catch tasks that attempt to return from their implementing function.\r
  56  */\r
  57 static void prvTaskExitError( void );\r
  58 \r
  59 /*-----------------------------------------------------------*/\r
  60 \r
  61 /* Used to program the machine timer compare register. */\r
  62 uint64_t ullNextTime = 0ULL;\r
  63 const uint64_t *pullNextTime = &ullNextTime;\r
  64 const uint32_t ulTimerIncrementsForOneTick = ( uint32_t ) ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ); /* Assumes increment won't go over 32-bits. */\r
  65 volatile uint64_t * const pullMachineTimerCompareRegister = ( volatile uint64_t * const ) ( configCLINT_BASE_ADDRESS + 0x4000 );\r
  66 \r
  67 /* Set configCHECK_FOR_STACK_OVERFLOW to 3 to add ISR stack checking to task\r
  68 stack checking.  A problem in the ISR stack will trigger an assert, not call the\r
  69 stack overflow hook function (because the stack overflow hook is specific to a\r
  70 task stack, not the ISR stack). */\r
  71 #if( configCHECK_FOR_STACK_OVERFLOW > 2 )\r
  72         #warning This path not tested, or even compiled yet.\r
  73         /* Don't use 0xa5 as the stack fill bytes as that is used by the kernerl for\r
  74         the task stacks, and so will legitimately appear in many positions within\r
  75         the ISR stack. */\r
  76         #define portISR_STACK_FILL_BYTE 0xee\r
  77 \r
  78         static const uint8_t ucExpectedStackBytes[] = {\r
  79                                                                         portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE,             \\r
  80                                                                         portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE,             \\r
  81                                                                         portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE,             \\r
  82                                                                         portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE,             \\r
  83                                                                         portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE };   \\r
  84 \r
  85         #define portCHECK_ISR_STACK() configASSERT( ( memcmp( ( void * ) xISRStack, ( void * ) ucExpectedStackBytes, sizeof( ucExpectedStackBytes ) ) == 0 ) )\r
  86 #else\r
  87         /* Define the function away. */\r
  88         #define portCHECK_ISR_STACK()\r
  89 #endif /* configCHECK_FOR_STACK_OVERFLOW > 2 */\r
  90 \r
  91 /*-----------------------------------------------------------*/\r
  92 \r
  93 void prvTaskExitError( void )\r
  94 {\r
  95 volatile uint32_t ulx = 0;\r
  96 \r
  97         /* A function that implements a task must not exit or attempt to return to\r
  98         its caller as there is nothing to return to.  If a task wants to exit it\r
  99         should instead call vTaskDelete( NULL ).\r
 100 \r
 101         Artificially force an assert() to be triggered if configASSERT() is\r
 102         defined, then stop here so application writers can catch the error. */\r
 103         configASSERT( ulx == ~0UL );\r
 104         portDISABLE_INTERRUPTS();\r
 105         for( ;; );\r
 106 }\r
 107 /*-----------------------------------------------------------*/\r
 108 \r
 109 /*\r
 110  * See header file for description.\r
 111  */\r
 112 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )\r
 113 {\r
 114 uint32_t mstatus;\r
 115 const uint32_t ulMPIE_Bit = 0x80, ulMPP_Bits = 0x1800;\r
 116         /*\r
 117            X1 to X31 integer registers for the 'I' profile, X1 to X15 for the 'E' profile.\r
 118 \r
 119                 Register        ABI Name                Description                                     Saver\r
 120                 x0                      zero                    Hard-wired zero                                 -\r
 121                 x1                      ra                              Return address                                  Caller\r
 122                 x2                      sp                              Stack pointer                                   Callee\r
 123                 x3                      gp                              Global pointer                                  -\r
 124                 x4                      tp                              Thread pointer                                  -\r
 125                 x5-7            t0-2                    Temporaries                                     Caller\r
 126                 x8                      s0/fp                   Saved register/Frame pointer    Callee\r
 127                 x9                      s1                              Saved register                                  Callee\r
 128                 x10-11          a0-1                    Function Arguments/return values Caller\r
 129                 x12-17          a2-7                    Function arguments                              Caller\r
 130                 x18-27          s2-11                   Saved registers                                 Callee\r
 131                 x28-31          t3-6                    Temporaries                                     Caller\r
 132         */\r
 133 \r
 134         /* Start task with interrupt enabled. */\r
 135         __asm volatile ("csrr %0, mstatus" : "=r"(mstatus));\r
 136         mstatus |= ulMPIE_Bit | ulMPP_Bits;\r
 137         pxTopOfStack--;\r
 138         *pxTopOfStack = mstatus;\r
 139 \r
 140         /* Numbers correspond to the x register number. */\r
 141         pxTopOfStack--;\r
 142         *pxTopOfStack = ( StackType_t ) 31;\r
 143         pxTopOfStack--;\r
 144         *pxTopOfStack = ( StackType_t ) 30;\r
 145         pxTopOfStack--;\r
 146         *pxTopOfStack = ( StackType_t ) 29;\r
 147         pxTopOfStack--;\r
 148         *pxTopOfStack = ( StackType_t ) 28;\r
 149         pxTopOfStack--;\r
 150         *pxTopOfStack = ( StackType_t ) 27;\r
 151         pxTopOfStack--;\r
 152         *pxTopOfStack = ( StackType_t ) 26;\r
 153         pxTopOfStack--;\r
 154         *pxTopOfStack = ( StackType_t ) 25;\r
 155         pxTopOfStack--;\r
 156         *pxTopOfStack = ( StackType_t ) 24;\r
 157         pxTopOfStack--;\r
 158         *pxTopOfStack = ( StackType_t ) 23;\r
 159         pxTopOfStack--;\r
 160         *pxTopOfStack = ( StackType_t ) 22;\r
 161         pxTopOfStack--;\r
 162         *pxTopOfStack = ( StackType_t ) 21;\r
 163         pxTopOfStack--;\r
 164         *pxTopOfStack = ( StackType_t ) 20;\r
 165         pxTopOfStack--;\r
 166         *pxTopOfStack = ( StackType_t ) 19;\r
 167         pxTopOfStack--;\r
 168         *pxTopOfStack = ( StackType_t ) 18;\r
 169         pxTopOfStack--;\r
 170         *pxTopOfStack = ( StackType_t ) 17;\r
 171         pxTopOfStack--;\r
 172         *pxTopOfStack = ( StackType_t ) 16;\r
 173         pxTopOfStack--;\r
 174         *pxTopOfStack = ( StackType_t ) 15;\r
 175         pxTopOfStack--;\r
 176         *pxTopOfStack = ( StackType_t ) 14;\r
 177         pxTopOfStack--;\r
 178         *pxTopOfStack = ( StackType_t ) 13;\r
 179         pxTopOfStack--;\r
 180         *pxTopOfStack = ( StackType_t ) 12;\r
 181         pxTopOfStack--;\r
 182         *pxTopOfStack = ( StackType_t ) 11;\r
 183         pxTopOfStack--;\r
 184         *pxTopOfStack = ( StackType_t ) pvParameters;\r
 185         pxTopOfStack--;\r
 186         *pxTopOfStack = ( StackType_t ) 9;\r
 187         pxTopOfStack--;\r
 188         *pxTopOfStack = ( StackType_t ) 8;\r
 189         pxTopOfStack--;\r
 190         *pxTopOfStack = ( StackType_t ) 7;\r
 191         pxTopOfStack--;\r
 192         *pxTopOfStack = ( StackType_t ) 6;\r
 193         pxTopOfStack--;\r
 194         *pxTopOfStack = ( StackType_t ) 5;\r
 195         pxTopOfStack--;\r
 196 //      *pxTopOfStack = ( StackType_t ) 4;  /* Thread pointer. */\r
 197 //      pxTopOfStack--;\r
 198 //      *pxTopOfStack = ( StackType_t ) 3;  /* Global pointer. */\r
 199 //      pxTopOfStack--;\r
 200 //      *pxTopOfStack = ( StackType_t ) 2;  /* Stack pointer. */\r
 201 //      pxTopOfStack--;\r
 202         *pxTopOfStack = ( StackType_t ) prvTaskExitError;\r
 203         pxTopOfStack--;\r
 204         *pxTopOfStack = ( StackType_t ) pxCode;\r
 205 \r
 206         return pxTopOfStack;\r
 207 }\r
 208 /*-----------------------------------------------------------*/\r
 209 \r
 210 void vPortSetupTimerInterrupt( void )\r
 211 {\r
 212 uint32_t ulCurrentTimeHigh, ulCurrentTimeLow;\r
 213 volatile uint32_t * const pulTimeHigh = ( volatile uint32_t * const ) ( configCLINT_BASE_ADDRESS + 0xBFFC );\r
 214 volatile uint32_t * const pulTimeLow = ( volatile uint32_t * const ) ( configCLINT_BASE_ADDRESS + 0xBFF8 );\r
 215 \r
 216         do\r
 217         {\r
 218                 ulCurrentTimeHigh = *pulTimeHigh;\r
 219                 ulCurrentTimeLow = *pulTimeLow;\r
 220         } while( ulCurrentTimeHigh != *pulTimeHigh );\r
 221 \r
 222         ullNextTime = ( uint64_t ) ulCurrentTimeHigh;\r
 223         ullNextTime <<= 32ULL;\r
 224         ullNextTime |= ( uint64_t ) ulCurrentTimeLow;\r
 225         ullNextTime += ( uint64_t ) ulTimerIncrementsForOneTick;\r
 226         *pullMachineTimerCompareRegister = ullNextTime;\r
 227 \r
 228         /* Prepare the time to use after the next tick interrupt. */\r
 229         ullNextTime += ( uint64_t ) ulTimerIncrementsForOneTick;\r
 230 \r
 231         /* Enable timer interrupt. */\r
 232         __asm volatile( "csrs mie, %0" :: "r"(0x80) ); /* 1<<7 for timer interrupt. */\r
 233 }\r
 234 /*-----------------------------------------------------------*/\r
 235 \r
 236 BaseType_t xPortStartScheduler( void )\r
 237 {\r
 238 extern void xPortStartFirstTask( void );\r
 239 \r
 240         #if( configASSERT_DEFINED == 1 )\r
 241         {\r
 242                 volatile uint32_t mtvec = 0;\r
 243 \r
 244                 /* Check the least significant two bits of mtvec are 00 - indicating\r
 245                 single vector mode. */\r
 246                 __asm volatile( "csrr %0, mtvec" : "=r"( mtvec ) );\r
 247                 configASSERT( ( mtvec & 0x03UL ) == 0 );\r
 248 \r
 249                 /* Check alignment of the interrupt stack - which is the same as the\r
 250                 stack that was being used by main() prior to the scheduler being\r
 251                 started. */\r
 252                 configASSERT( ( xISRStackTop & portBYTE_ALIGNMENT_MASK ) == 0 );\r
 253         }\r
 254         #endif\r
 255 \r
 256         vPortSetupTimerInterrupt();\r
 257         xPortStartFirstTask();\r
 258 \r
 259         /* Should not get here as after calling xPortStartFirstTask() only tasks\r
 260         should be executing. */\r
 261         return pdFAIL;\r
 262 }\r
 263 /*-----------------------------------------------------------*/\r
 264 \r
 265 void vPortEndScheduler( void )\r
 266 {\r
 267         /* Not implemented. */\r
 268         for( ;; );\r
 269 }\r
 270 \r
 271 \r
 272 \r
 273 \r