2 FreeRTOS V7.6.0 - Copyright (C) 2013 Real Time Engineers Ltd.
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5 VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
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7 ***************************************************************************
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9 * FreeRTOS provides completely free yet professionally developed, *
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10 * robust, strictly quality controlled, supported, and cross *
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11 * platform software that has become a de facto standard. *
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13 * Help yourself get started quickly and support the FreeRTOS *
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14 * project by purchasing a FreeRTOS tutorial book, reference *
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15 * manual, or both from: http://www.FreeRTOS.org/Documentation *
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19 ***************************************************************************
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21 This file is part of the FreeRTOS distribution.
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23 FreeRTOS is free software; you can redistribute it and/or modify it under
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24 the terms of the GNU General Public License (version 2) as published by the
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25 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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27 >>! NOTE: The modification to the GPL is included to allow you to distribute
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28 >>! a combined work that includes FreeRTOS without being obliged to provide
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29 >>! the source code for proprietary components outside of the FreeRTOS
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32 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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33 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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34 FOR A PARTICULAR PURPOSE. Full license text is available from the following
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35 link: http://www.freertos.org/a00114.html
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39 ***************************************************************************
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41 * Having a problem? Start by reading the FAQ "My application does *
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42 * not run, what could be wrong?" *
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44 * http://www.FreeRTOS.org/FAQHelp.html *
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46 ***************************************************************************
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48 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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49 license and Real Time Engineers Ltd. contact details.
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51 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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52 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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53 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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55 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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56 Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
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57 licenses offer ticketed support, indemnification and middleware.
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59 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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60 engineered and independently SIL3 certified version for use in safety and
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61 mission critical applications that require provable dependability.
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67 /*-----------------------------------------------------------
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68 * Implementation of functions defined in portable.h for the ARM7 port.
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70 * Components that can be compiled to either ARM or THUMB mode are
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71 * contained in this file. The ISR routines, which can only be compiled
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72 * to ARM mode are contained in portISR.c.
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73 *----------------------------------------------------------*/
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76 /* Standard includes. */
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79 /* Scheduler includes. */
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80 #include "FreeRTOS.h"
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83 /* Constants required to setup the task context. */
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84 #define portINITIAL_SPSR ( ( StackType_t ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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85 #define portTHUMB_MODE_BIT ( ( StackType_t ) 0x20 )
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86 #define portINSTRUCTION_SIZE ( ( StackType_t ) 4 )
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87 #define portNO_CRITICAL_SECTION_NESTING ( ( StackType_t ) 0 )
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89 /* Constants required to setup the tick ISR. */
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90 #define portENABLE_TIMER ( ( uint8_t ) 0x01 )
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91 #define portPRESCALE_VALUE 0x00
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92 #define portINTERRUPT_ON_MATCH ( ( uint32_t ) 0x01 )
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93 #define portRESET_COUNT_ON_MATCH ( ( uint32_t ) 0x02 )
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95 /* Constants required to setup the VIC for the tick ISR. */
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96 #define portTIMER_VIC_CHANNEL ( ( uint32_t ) 0x0004 )
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97 #define portTIMER_VIC_CHANNEL_BIT ( ( uint32_t ) 0x0010 )
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98 #define portTIMER_VIC_ENABLE ( ( uint32_t ) 0x0020 )
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100 /*-----------------------------------------------------------*/
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102 /* Setup the timer to generate the tick interrupts. */
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103 static void prvSetupTimerInterrupt( void );
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106 * The scheduler can only be started from ARM mode, so
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107 * vPortISRStartFirstSTask() is defined in portISR.c.
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109 extern void vPortISRStartFirstTask( void );
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111 /*-----------------------------------------------------------*/
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114 * Initialise the stack of a task to look exactly as if a call to
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115 * portSAVE_CONTEXT had been called.
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117 * See header file for description.
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119 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
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121 StackType_t *pxOriginalTOS;
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123 pxOriginalTOS = pxTopOfStack;
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125 /* To ensure asserts in tasks.c don't fail, although in this case the assert
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126 is not really required. */
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129 /* Setup the initial stack of the task. The stack is set exactly as
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130 expected by the portRESTORE_CONTEXT() macro. */
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132 /* First on the stack is the return address - which in this case is the
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133 start of the task. The offset is added to make the return address appear
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134 as it would within an IRQ ISR. */
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135 *pxTopOfStack = ( StackType_t ) pxCode + portINSTRUCTION_SIZE;
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138 *pxTopOfStack = ( StackType_t ) 0xaaaaaaaa; /* R14 */
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140 *pxTopOfStack = ( StackType_t ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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142 *pxTopOfStack = ( StackType_t ) 0x12121212; /* R12 */
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144 *pxTopOfStack = ( StackType_t ) 0x11111111; /* R11 */
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146 *pxTopOfStack = ( StackType_t ) 0x10101010; /* R10 */
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148 *pxTopOfStack = ( StackType_t ) 0x09090909; /* R9 */
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150 *pxTopOfStack = ( StackType_t ) 0x08080808; /* R8 */
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152 *pxTopOfStack = ( StackType_t ) 0x07070707; /* R7 */
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154 *pxTopOfStack = ( StackType_t ) 0x06060606; /* R6 */
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156 *pxTopOfStack = ( StackType_t ) 0x05050505; /* R5 */
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158 *pxTopOfStack = ( StackType_t ) 0x04040404; /* R4 */
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160 *pxTopOfStack = ( StackType_t ) 0x03030303; /* R3 */
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162 *pxTopOfStack = ( StackType_t ) 0x02020202; /* R2 */
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164 *pxTopOfStack = ( StackType_t ) 0x01010101; /* R1 */
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167 /* When the task starts is will expect to find the function parameter in
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169 *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
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172 /* The last thing onto the stack is the status register, which is set for
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173 system mode, with interrupts enabled. */
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174 *pxTopOfStack = ( StackType_t ) portINITIAL_SPSR;
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176 if( ( ( uint32_t ) pxCode & 0x01UL ) != 0x00 )
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178 /* We want the task to start in thumb mode. */
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179 *pxTopOfStack |= portTHUMB_MODE_BIT;
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184 /* Some optimisation levels use the stack differently to others. This
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185 means the interrupt flags cannot always be stored on the stack and will
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186 instead be stored in a variable, which is then saved as part of the
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188 *pxTopOfStack = portNO_CRITICAL_SECTION_NESTING;
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190 return pxTopOfStack;
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192 /*-----------------------------------------------------------*/
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194 BaseType_t xPortStartScheduler( void )
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196 /* Start the timer that generates the tick ISR. Interrupts are disabled
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198 prvSetupTimerInterrupt();
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200 /* Start the first task. */
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201 vPortISRStartFirstTask();
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203 /* Should not get here! */
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206 /*-----------------------------------------------------------*/
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208 void vPortEndScheduler( void )
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210 /* It is unlikely that the ARM port will require this function as there
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211 is nothing to return to. */
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213 /*-----------------------------------------------------------*/
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216 * Setup the timer 0 to generate the tick interrupts at the required frequency.
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218 static void prvSetupTimerInterrupt( void )
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220 uint32_t ulCompareMatch;
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221 extern void ( vTickISR )( void );
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223 /* A 1ms tick does not require the use of the timer prescale. This is
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224 defaulted to zero but can be used if necessary. */
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225 T0_PR = portPRESCALE_VALUE;
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227 /* Calculate the match value required for our wanted tick rate. */
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228 ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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230 /* Protect against divide by zero. Using an if() statement still results
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231 in a warning - hence the #if. */
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232 #if portPRESCALE_VALUE != 0
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234 ulCompareMatch /= ( portPRESCALE_VALUE + 1 );
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237 T0_MR0 = ulCompareMatch;
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239 /* Generate tick with timer 0 compare match. */
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240 T0_MCR = portRESET_COUNT_ON_MATCH | portINTERRUPT_ON_MATCH;
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242 /* Setup the VIC for the timer. */
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243 VICIntSelect &= ~( portTIMER_VIC_CHANNEL_BIT );
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244 VICIntEnable |= portTIMER_VIC_CHANNEL_BIT;
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246 /* The ISR installed depends on whether the preemptive or cooperative
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247 scheduler is being used. */
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249 VICVectAddr0 = ( int32_t ) vTickISR;
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250 VICVectCntl0 = portTIMER_VIC_CHANNEL | portTIMER_VIC_ENABLE;
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252 /* Start the timer - interrupts are disabled when this function is called
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253 so it is okay to do this here. */
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254 T0_TCR = portENABLE_TIMER;
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256 /*-----------------------------------------------------------*/
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