2 FreeRTOS V8.2.0rc1 - Copyright (C) 2014 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 This file is part of the FreeRTOS distribution.
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9 FreeRTOS is free software; you can redistribute it and/or modify it under
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10 the terms of the GNU General Public License (version 2) as published by the
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11 Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.
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13 >>! NOTE: The modification to the GPL is included to allow you to !<<
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14 >>! distribute a combined work that includes FreeRTOS without being !<<
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15 >>! obliged to provide the source code for proprietary components !<<
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16 >>! outside of the FreeRTOS kernel. !<<
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18 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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19 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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20 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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21 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * Having a problem? Start by reading the FAQ "My application does *
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28 * not run, what could be wrong?". Have you defined configASSERT()? *
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30 * http://www.FreeRTOS.org/FAQHelp.html *
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32 ***************************************************************************
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34 ***************************************************************************
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36 * FreeRTOS provides completely free yet professionally developed, *
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37 * robust, strictly quality controlled, supported, and cross *
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38 * platform software that is more than just the market leader, it *
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39 * is the industry's de facto standard. *
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41 * Help yourself get started quickly while simultaneously helping *
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42 * to support the FreeRTOS project by purchasing a FreeRTOS *
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43 * tutorial book, reference manual, or both: *
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44 * http://www.FreeRTOS.org/Documentation *
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46 ***************************************************************************
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48 ***************************************************************************
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50 * Investing in training allows your team to be as productive as *
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51 * possible as early as possible, lowering your overall development *
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52 * cost, and enabling you to bring a more robust product to market *
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53 * earlier than would otherwise be possible. Richard Barry is both *
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54 * the architect and key author of FreeRTOS, and so also the world's *
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55 * leading authority on what is the world's most popular real time *
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56 * kernel for deeply embedded MCU designs. Obtaining your training *
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57 * from Richard ensures your team will gain directly from his in-depth *
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58 * product knowledge and years of usage experience. Contact Real Time *
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59 * Engineers Ltd to enquire about the FreeRTOS Masterclass, presented *
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60 * by Richard Barry: http://www.FreeRTOS.org/contact
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62 ***************************************************************************
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64 ***************************************************************************
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66 * You are receiving this top quality software for free. Please play *
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67 * fair and reciprocate by reporting any suspected issues and *
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68 * participating in the community forum: *
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69 * http://www.FreeRTOS.org/support *
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73 ***************************************************************************
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75 http://www.FreeRTOS.org - Documentation, books, training, latest versions,
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76 license and Real Time Engineers Ltd. contact details.
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78 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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79 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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80 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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82 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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83 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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85 http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
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86 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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87 licenses offer ticketed support, indemnification and commercial middleware.
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89 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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90 engineered and independently SIL3 certified version for use in safety and
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91 mission critical applications that require provable dependability.
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97 /*-----------------------------------------------------------
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98 * Implementation of functions defined in portable.h for the ARM7 port.
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100 * Components that can be compiled to either ARM or THUMB mode are
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101 * contained in this file. The ISR routines, which can only be compiled
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102 * to ARM mode are contained in portISR.c.
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103 *----------------------------------------------------------*/
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106 /* Standard includes. */
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107 #include <stdlib.h>
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109 /* Scheduler includes. */
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110 #include "FreeRTOS.h"
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113 /* Constants required to setup the task context. */
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114 #define portINITIAL_SPSR ( ( StackType_t ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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115 #define portTHUMB_MODE_BIT ( ( StackType_t ) 0x20 )
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116 #define portINSTRUCTION_SIZE ( ( StackType_t ) 4 )
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117 #define portNO_CRITICAL_SECTION_NESTING ( ( StackType_t ) 0 )
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119 /* Constants required to setup the tick ISR. */
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120 #define portENABLE_TIMER ( ( uint8_t ) 0x01 )
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121 #define portPRESCALE_VALUE 0x00
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122 #define portINTERRUPT_ON_MATCH ( ( uint32_t ) 0x01 )
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123 #define portRESET_COUNT_ON_MATCH ( ( uint32_t ) 0x02 )
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125 /* Constants required to setup the VIC for the tick ISR. */
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126 #define portTIMER_VIC_CHANNEL ( ( uint32_t ) 0x0004 )
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127 #define portTIMER_VIC_CHANNEL_BIT ( ( uint32_t ) 0x0010 )
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128 #define portTIMER_VIC_ENABLE ( ( uint32_t ) 0x0020 )
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130 /*-----------------------------------------------------------*/
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132 /* Setup the timer to generate the tick interrupts. */
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133 static void prvSetupTimerInterrupt( void );
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136 * The scheduler can only be started from ARM mode, so
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137 * vPortISRStartFirstSTask() is defined in portISR.c.
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139 extern void vPortISRStartFirstTask( void );
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141 /*-----------------------------------------------------------*/
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144 * Initialise the stack of a task to look exactly as if a call to
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145 * portSAVE_CONTEXT had been called.
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147 * See header file for description.
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149 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
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151 StackType_t *pxOriginalTOS;
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153 pxOriginalTOS = pxTopOfStack;
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155 /* To ensure asserts in tasks.c don't fail, although in this case the assert
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156 is not really required. */
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159 /* Setup the initial stack of the task. The stack is set exactly as
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160 expected by the portRESTORE_CONTEXT() macro. */
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162 /* First on the stack is the return address - which in this case is the
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163 start of the task. The offset is added to make the return address appear
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164 as it would within an IRQ ISR. */
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165 *pxTopOfStack = ( StackType_t ) pxCode + portINSTRUCTION_SIZE;
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168 *pxTopOfStack = ( StackType_t ) 0x00000000; /* R14 */
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170 *pxTopOfStack = ( StackType_t ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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172 *pxTopOfStack = ( StackType_t ) 0x12121212; /* R12 */
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174 *pxTopOfStack = ( StackType_t ) 0x11111111; /* R11 */
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176 *pxTopOfStack = ( StackType_t ) 0x10101010; /* R10 */
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178 *pxTopOfStack = ( StackType_t ) 0x09090909; /* R9 */
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180 *pxTopOfStack = ( StackType_t ) 0x08080808; /* R8 */
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182 *pxTopOfStack = ( StackType_t ) 0x07070707; /* R7 */
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184 *pxTopOfStack = ( StackType_t ) 0x06060606; /* R6 */
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186 *pxTopOfStack = ( StackType_t ) 0x05050505; /* R5 */
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188 *pxTopOfStack = ( StackType_t ) 0x04040404; /* R4 */
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190 *pxTopOfStack = ( StackType_t ) 0x03030303; /* R3 */
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192 *pxTopOfStack = ( StackType_t ) 0x02020202; /* R2 */
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194 *pxTopOfStack = ( StackType_t ) 0x01010101; /* R1 */
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197 /* When the task starts is will expect to find the function parameter in
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199 *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
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202 /* The last thing onto the stack is the status register, which is set for
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203 system mode, with interrupts enabled. */
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204 *pxTopOfStack = ( StackType_t ) portINITIAL_SPSR;
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206 if( ( ( uint32_t ) pxCode & 0x01UL ) != 0x00 )
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208 /* We want the task to start in thumb mode. */
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209 *pxTopOfStack |= portTHUMB_MODE_BIT;
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214 /* Some optimisation levels use the stack differently to others. This
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215 means the interrupt flags cannot always be stored on the stack and will
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216 instead be stored in a variable, which is then saved as part of the
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218 *pxTopOfStack = portNO_CRITICAL_SECTION_NESTING;
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220 return pxTopOfStack;
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222 /*-----------------------------------------------------------*/
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224 BaseType_t xPortStartScheduler( void )
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226 /* Start the timer that generates the tick ISR. Interrupts are disabled
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228 prvSetupTimerInterrupt();
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230 /* Start the first task. */
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231 vPortISRStartFirstTask();
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233 /* Should not get here! */
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236 /*-----------------------------------------------------------*/
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238 void vPortEndScheduler( void )
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240 /* It is unlikely that the ARM port will require this function as there
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241 is nothing to return to. */
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243 /*-----------------------------------------------------------*/
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246 * Setup the timer 0 to generate the tick interrupts at the required frequency.
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248 static void prvSetupTimerInterrupt( void )
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250 uint32_t ulCompareMatch;
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252 PCLKSEL0 = (PCLKSEL0 & (~(0x3<<2))) | (0x01 << 2);
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253 T0TCR = 2; /* Stop and reset the timer */
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254 T0CTCR = 0; /* Timer mode */
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256 /* A 1ms tick does not require the use of the timer prescale. This is
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257 defaulted to zero but can be used if necessary. */
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258 T0PR = portPRESCALE_VALUE;
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260 /* Calculate the match value required for our wanted tick rate. */
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261 ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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263 /* Protect against divide by zero. Using an if() statement still results
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264 in a warning - hence the #if. */
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265 #if portPRESCALE_VALUE != 0
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267 ulCompareMatch /= ( portPRESCALE_VALUE + 1 );
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270 T0MR1 = ulCompareMatch;
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272 /* Generate tick with timer 0 compare match. */
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273 T0MCR = (3 << 3); /* Reset timer on match and generate interrupt */
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275 /* Setup the VIC for the timer. */
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276 VICIntEnable = 0x00000010;
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278 /* The ISR installed depends on whether the preemptive or cooperative
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279 scheduler is being used. */
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280 #if configUSE_PREEMPTION == 1
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282 extern void ( vPreemptiveTick )( void );
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283 VICVectAddr4 = ( int32_t ) vPreemptiveTick;
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287 extern void ( vNonPreemptiveTick )( void );
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288 VICVectAddr4 = ( int32_t ) vNonPreemptiveTick;
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294 /* Start the timer - interrupts are disabled when this function is called
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295 so it is okay to do this here. */
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296 T0TCR = portENABLE_TIMER;
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298 /*-----------------------------------------------------------*/
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