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 /*\r
  38  * Setup the timer to generate the tick interrupts.  The implementation in this\r
  39  * file is weak to allow application writers to change the timer used to\r
  40  * generate the tick interrupt.\r
  41  */\r
  42 void vPortSetupTimerInterrupt( void ) __attribute__(( weak ));\r
  43 \r
  44 /*\r
  45  * Used to catch tasks that attempt to return from their implementing function.\r
  46  */\r
  47 static void prvTaskExitError( void );\r
  48 \r
  49 /*-----------------------------------------------------------*/\r
  50 \r
  51 /* Used to program the machine timer compare register. */\r
  52 static uint64_t ullNextTime = 0ULL;\r
  53 static const uint64_t ullTimerIncrementsForOneTick = ( uint64_t ) ( configCPU_CLOCK_HZ / configTICK_RATE_HZ );\r
  54 static volatile uint64_t * const pullMachineTimerCompareRegister = ( volatile uint64_t * const ) ( configCTRL_BASE + 0x4000 );\r
  55 \r
  56 /*-----------------------------------------------------------*/\r
  57 \r
  58 void prvTaskExitError( void )\r
  59 {\r
  60 volatile uint32_t ulx = 0;\r
  61 \r
  62         /* A function that implements a task must not exit or attempt to return to\r
  63         its caller as there is nothing to return to.  If a task wants to exit it\r
  64         should instead call vTaskDelete( NULL ).\r
  65 \r
  66         Artificially force an assert() to be triggered if configASSERT() is\r
  67         defined, then stop here so application writers can catch the error. */\r
  68         configASSERT( ulx == ~0UL );\r
  69         portDISABLE_INTERRUPTS();\r
  70         for( ;; );\r
  71 }\r
  72 /*-----------------------------------------------------------*/\r
  73 \r
  74 /*\r
  75  * See header file for description.\r
  76  */\r
  77 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )\r
  78 {\r
  79 uint32_t mstatus;\r
  80 const uint32_t ulMPIE_Bit = 0x80, ulMPP_Bits = 0x1800;\r
  81         /*\r
  82            X1 to X31 integer registers for the 'I' profile, X1 to X15 for the 'E' profile.\r
  83 \r
  84                 Register        ABI Name                Description                                     Saver\r
  85                 x0                      zero                    Hard-wired zero                                 -\r
  86                 x1                      ra                              Return address                                  Caller\r
  87                 x2                      sp                              Stack pointer                                   Callee\r
  88                 x3                      gp                              Global pointer                                  -\r
  89                 x4                      tp                              Thread pointer                                  -\r
  90                 x5-7            t0-2                    Temporaries                                     Caller\r
  91                 x8                      s0/fp                   Saved register/Frame pointer    Callee\r
  92                 x9                      s1                              Saved register                                  Callee\r
  93                 x10-11          a0-1                    Function Arguments/return values Caller\r
  94                 x12-17          a2-7                    Function arguments                              Caller\r
  95                 x18-27          s2-11                   Saved registers                                 Callee\r
  96                 x28-31          t3-6                    Temporaries                                     Caller\r
  97         */\r
  98 \r
  99         /* Start task with interrupt enabled. */\r
 100         __asm volatile ("csrr %0, mstatus" : "=r"(mstatus));\r
 101         mstatus |= ulMPIE_Bit | ulMPP_Bits;\r
 102         pxTopOfStack--;\r
 103         *pxTopOfStack = mstatus;\r
 104 \r
 105         /* Numbers correspond to the x register number. */\r
 106         pxTopOfStack--;\r
 107         *pxTopOfStack = ( StackType_t ) 31;\r
 108         pxTopOfStack--;\r
 109         *pxTopOfStack = ( StackType_t ) 30;\r
 110         pxTopOfStack--;\r
 111         *pxTopOfStack = ( StackType_t ) 29;\r
 112         pxTopOfStack--;\r
 113         *pxTopOfStack = ( StackType_t ) 28;\r
 114         pxTopOfStack--;\r
 115         *pxTopOfStack = ( StackType_t ) 27;\r
 116         pxTopOfStack--;\r
 117         *pxTopOfStack = ( StackType_t ) 26;\r
 118         pxTopOfStack--;\r
 119         *pxTopOfStack = ( StackType_t ) 25;\r
 120         pxTopOfStack--;\r
 121         *pxTopOfStack = ( StackType_t ) 24;\r
 122         pxTopOfStack--;\r
 123         *pxTopOfStack = ( StackType_t ) 23;\r
 124         pxTopOfStack--;\r
 125         *pxTopOfStack = ( StackType_t ) 22;\r
 126         pxTopOfStack--;\r
 127         *pxTopOfStack = ( StackType_t ) 21;\r
 128         pxTopOfStack--;\r
 129         *pxTopOfStack = ( StackType_t ) 20;\r
 130         pxTopOfStack--;\r
 131         *pxTopOfStack = ( StackType_t ) 19;\r
 132         pxTopOfStack--;\r
 133         *pxTopOfStack = ( StackType_t ) 18;\r
 134         pxTopOfStack--;\r
 135         *pxTopOfStack = ( StackType_t ) 17;\r
 136         pxTopOfStack--;\r
 137         *pxTopOfStack = ( StackType_t ) 16;\r
 138         pxTopOfStack--;\r
 139         *pxTopOfStack = ( StackType_t ) 15;\r
 140         pxTopOfStack--;\r
 141         *pxTopOfStack = ( StackType_t ) 14;\r
 142         pxTopOfStack--;\r
 143         *pxTopOfStack = ( StackType_t ) 13;\r
 144         pxTopOfStack--;\r
 145         *pxTopOfStack = ( StackType_t ) 12;\r
 146         pxTopOfStack--;\r
 147         *pxTopOfStack = ( StackType_t ) 11;\r
 148         pxTopOfStack--;\r
 149         *pxTopOfStack = ( StackType_t ) pvParameters;\r
 150         pxTopOfStack--;\r
 151         *pxTopOfStack = ( StackType_t ) 9;\r
 152         pxTopOfStack--;\r
 153         *pxTopOfStack = ( StackType_t ) 8;\r
 154         pxTopOfStack--;\r
 155         *pxTopOfStack = ( StackType_t ) 7;\r
 156         pxTopOfStack--;\r
 157         *pxTopOfStack = ( StackType_t ) 6;\r
 158         pxTopOfStack--;\r
 159         *pxTopOfStack = ( StackType_t ) 5;\r
 160         pxTopOfStack--;\r
 161 //      *pxTopOfStack = ( StackType_t ) 4;  /* Thread pointer. */\r
 162 //      pxTopOfStack--;\r
 163 //      *pxTopOfStack = ( StackType_t ) 3;  /* Global pointer. */\r
 164 //      pxTopOfStack--;\r
 165 //      *pxTopOfStack = ( StackType_t ) 2;  /* Stack pointer. */\r
 166 //      pxTopOfStack--;\r
 167         *pxTopOfStack = ( StackType_t ) prvTaskExitError;\r
 168         pxTopOfStack--;\r
 169         *pxTopOfStack = ( StackType_t ) pxCode;\r
 170 \r
 171         return pxTopOfStack;\r
 172 }\r
 173 /*-----------------------------------------------------------*/\r
 174 \r
 175 void vPortSetupTimerInterrupt( void )\r
 176 {\r
 177 uint32_t ulCurrentTimeHigh, ulCurrentTimeLow;\r
 178 volatile uint32_t * const pulTimeHigh = ( volatile uint32_t * const ) ( configCTRL_BASE + 0xBFFC );\r
 179 volatile uint32_t * const pulTimeLow = ( volatile uint32_t * const ) ( configCTRL_BASE + 0xBFF8 );\r
 180 \r
 181         do\r
 182         {\r
 183                 ulCurrentTimeHigh = *pulTimeHigh;\r
 184                 ulCurrentTimeLow = *pulTimeLow;\r
 185         } while( ulCurrentTimeHigh != *pulTimeHigh );\r
 186 \r
 187         ullNextTime = ( uint64_t ) ulCurrentTimeHigh;\r
 188         ullNextTime <<= 32ULL;\r
 189         ullNextTime |= ( uint64_t ) ulCurrentTimeLow;\r
 190         ullNextTime += ullTimerIncrementsForOneTick;\r
 191         *pullMachineTimerCompareRegister = ullNextTime;\r
 192 \r
 193         /* Prepare the time to use after the next tick interrupt. */\r
 194         ullNextTime += ullTimerIncrementsForOneTick;\r
 195 \r
 196         /* Enable timer interrupt */\r
 197         __asm volatile( "csrs mie, %0" :: "r"(0x80) ); /* 1<<7 for timer interrupt. */\r
 198 }\r
 199 /*-----------------------------------------------------------*/\r
 200 \r
 201 void Software_IRQHandler( void )\r
 202 {\r
 203 volatile uint32_t * const ulSoftInterrupt = ( uint32_t * ) configCTRL_BASE;\r
 204 \r
 205         vTaskSwitchContext();\r
 206 \r
 207         /* Clear software interrupt. */\r
 208         *( ( uint32_t * ) configCTRL_BASE ) &= 0x08UL;\r
 209 }\r
 210 /*-----------------------------------------------------------*/\r
 211 \r
 212 void Timer_IRQHandler( void )\r
 213 {\r
 214 extern void vTaskSwitchContext( void );\r
 215 \r
 216         /* Reload for the next timer interrupt. */\r
 217         *pullMachineTimerCompareRegister = ullNextTime;\r
 218         ullNextTime += ullTimerIncrementsForOneTick;\r
 219 \r
 220         if( xTaskIncrementTick() != pdFALSE )\r
 221         {\r
 222                 vTaskSwitchContext();\r
 223         }\r
 224 }\r
 225 /*-----------------------------------------------------------*/\r
 226 \r
 227 BaseType_t xPortStartScheduler( void )\r
 228 {\r
 229 extern void xPortStartFirstTask( void );\r
 230 \r
 231         #if( configASSERT_DEFINED == 1 )\r
 232         {\r
 233                 volatile uint32_t mtvec = 0;\r
 234 \r
 235                 /* Check the least significant two bits of mtvec are 00 - indicating single\r
 236                 vector mode. */\r
 237                 __asm volatile( "csrr %0, mtvec" : "=r"( mtvec ) );\r
 238                 configASSERT( ( mtvec & 0x03UL ) == 0 );\r
 239         }\r
 240         #endif\r
 241 \r
 242         vPortSetupTimerInterrupt();\r
 243         xPortStartFirstTask();\r
 244 \r
 245         /* Should not get here as after calling xPortStartFirstTask() only tasks\r
 246         should be executing. */\r
 247         return pdFAIL;\r
 248 }\r
 249 \r
 250 \r
 251 \r