2 FreeRTOS V7.4.0 - Copyright (C) 2013 Real Time Engineers Ltd.
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4 FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT
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5 http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS tutorial books are available in pdf and paperback. *
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10 * Complete, revised, and edited pdf reference manuals are also *
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13 * Purchasing FreeRTOS documentation will not only help you, by *
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14 * ensuring you get running as quickly as possible and with an *
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15 * in-depth knowledge of how to use FreeRTOS, it will also help *
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16 * the FreeRTOS project to continue with its mission of providing *
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17 * professional grade, cross platform, de facto standard solutions *
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18 * for microcontrollers - completely free of charge! *
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20 * >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
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22 * Thank you for using FreeRTOS, and thank you for your support! *
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24 ***************************************************************************
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27 This file is part of the FreeRTOS distribution.
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29 FreeRTOS is free software; you can redistribute it and/or modify it under
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30 the terms of the GNU General Public License (version 2) as published by the
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31 Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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33 >>>>>>NOTE<<<<<< The modification to the GPL is included to allow you to
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34 distribute a combined work that includes FreeRTOS without being obliged to
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35 provide the source code for proprietary components outside of the FreeRTOS
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38 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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39 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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40 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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41 details. You should have received a copy of the GNU General Public License
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42 and the FreeRTOS license exception along with FreeRTOS; if not itcan be
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43 viewed here: http://www.freertos.org/a00114.html and also obtained by
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44 writing to Real Time Engineers Ltd., contact details for whom are available
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45 on the FreeRTOS WEB site.
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49 ***************************************************************************
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51 * Having a problem? Start by reading the FAQ "My application does *
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52 * not run, what could be wrong?" *
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54 * http://www.FreeRTOS.org/FAQHelp.html *
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56 ***************************************************************************
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59 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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60 license and Real Time Engineers Ltd. contact details.
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62 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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63 including FreeRTOS+Trace - an indispensable productivity tool, and our new
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64 fully thread aware and reentrant UDP/IP stack.
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66 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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67 Integrity Systems, who sell the code with commercial support,
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68 indemnification and middleware, under the OpenRTOS brand.
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70 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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71 engineered and independently SIL3 certified version for use in safety and
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72 mission critical applications that require provable dependability.
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76 /*-----------------------------------------------------------
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77 * Implementation of functions defined in portable.h for the ARM7 port.
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79 * Components that can be compiled to either ARM or THUMB mode are
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80 * contained in this file. The ISR routines, which can only be compiled
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81 * to ARM mode are contained in portISR.c.
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82 *----------------------------------------------------------*/
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85 /* Standard includes. */
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88 /* Scheduler includes. */
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89 #include "FreeRTOS.h"
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92 /* Constants required to setup the task context. */
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93 #define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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94 #define portTHUMB_MODE_BIT ( ( portSTACK_TYPE ) 0x20 )
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95 #define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 )
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96 #define portNO_CRITICAL_SECTION_NESTING ( ( portSTACK_TYPE ) 0 )
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98 /* Constants required to setup the tick ISR. */
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99 #define portENABLE_TIMER ( ( unsigned char ) 0x01 )
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100 #define portPRESCALE_VALUE 0x00
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101 #define portINTERRUPT_ON_MATCH ( ( unsigned long ) 0x01 )
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102 #define portRESET_COUNT_ON_MATCH ( ( unsigned long ) 0x02 )
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104 /* Constants required to setup the VIC for the tick ISR. */
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105 #define portTIMER_VIC_CHANNEL ( ( unsigned long ) 0x0004 )
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106 #define portTIMER_VIC_CHANNEL_BIT ( ( unsigned long ) 0x0010 )
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107 #define portTIMER_VIC_ENABLE ( ( unsigned long ) 0x0020 )
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109 /*-----------------------------------------------------------*/
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111 /* Setup the timer to generate the tick interrupts. */
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112 static void prvSetupTimerInterrupt( void );
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115 * The scheduler can only be started from ARM mode, so
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116 * vPortISRStartFirstSTask() is defined in portISR.c.
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118 extern void vPortISRStartFirstTask( void );
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120 /*-----------------------------------------------------------*/
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123 * Initialise the stack of a task to look exactly as if a call to
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124 * portSAVE_CONTEXT had been called.
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126 * See header file for description.
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128 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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130 portSTACK_TYPE *pxOriginalTOS;
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132 pxOriginalTOS = pxTopOfStack;
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134 /* To ensure asserts in tasks.c don't fail, although in this case the assert
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135 is not really required. */
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138 /* Setup the initial stack of the task. The stack is set exactly as
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139 expected by the portRESTORE_CONTEXT() macro. */
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141 /* First on the stack is the return address - which in this case is the
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142 start of the task. The offset is added to make the return address appear
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143 as it would within an IRQ ISR. */
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144 *pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
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147 *pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */
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149 *pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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151 *pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */
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153 *pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */
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155 *pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */
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157 *pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */
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159 *pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */
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161 *pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */
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163 *pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */
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165 *pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */
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167 *pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */
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169 *pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */
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171 *pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */
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173 *pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */
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176 /* When the task starts is will expect to find the function parameter in
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178 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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181 /* The last thing onto the stack is the status register, which is set for
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182 system mode, with interrupts enabled. */
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183 *pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR;
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185 if( ( ( unsigned long ) pxCode & 0x01UL ) != 0x00 )
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187 /* We want the task to start in thumb mode. */
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188 *pxTopOfStack |= portTHUMB_MODE_BIT;
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193 /* Some optimisation levels use the stack differently to others. This
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194 means the interrupt flags cannot always be stored on the stack and will
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195 instead be stored in a variable, which is then saved as part of the
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197 *pxTopOfStack = portNO_CRITICAL_SECTION_NESTING;
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199 return pxTopOfStack;
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201 /*-----------------------------------------------------------*/
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203 portBASE_TYPE xPortStartScheduler( void )
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205 /* Start the timer that generates the tick ISR. Interrupts are disabled
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207 prvSetupTimerInterrupt();
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209 /* Start the first task. */
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210 vPortISRStartFirstTask();
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212 /* Should not get here! */
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215 /*-----------------------------------------------------------*/
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217 void vPortEndScheduler( void )
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219 /* It is unlikely that the ARM port will require this function as there
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220 is nothing to return to. */
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222 /*-----------------------------------------------------------*/
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225 * Setup the timer 0 to generate the tick interrupts at the required frequency.
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227 static void prvSetupTimerInterrupt( void )
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229 unsigned long ulCompareMatch;
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230 extern void ( vTickISR )( void );
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232 /* A 1ms tick does not require the use of the timer prescale. This is
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233 defaulted to zero but can be used if necessary. */
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234 T0_PR = portPRESCALE_VALUE;
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236 /* Calculate the match value required for our wanted tick rate. */
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237 ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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239 /* Protect against divide by zero. Using an if() statement still results
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240 in a warning - hence the #if. */
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241 #if portPRESCALE_VALUE != 0
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243 ulCompareMatch /= ( portPRESCALE_VALUE + 1 );
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246 T0_MR0 = ulCompareMatch;
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248 /* Generate tick with timer 0 compare match. */
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249 T0_MCR = portRESET_COUNT_ON_MATCH | portINTERRUPT_ON_MATCH;
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251 /* Setup the VIC for the timer. */
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252 VICIntSelect &= ~( portTIMER_VIC_CHANNEL_BIT );
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253 VICIntEnable |= portTIMER_VIC_CHANNEL_BIT;
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255 /* The ISR installed depends on whether the preemptive or cooperative
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256 scheduler is being used. */
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258 VICVectAddr0 = ( long ) vTickISR;
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259 VICVectCntl0 = portTIMER_VIC_CHANNEL | portTIMER_VIC_ENABLE;
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261 /* Start the timer - interrupts are disabled when this function is called
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262 so it is okay to do this here. */
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263 T0_TCR = portENABLE_TIMER;
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265 /*-----------------------------------------------------------*/
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