2 FreeRTOS V7.4.2 - 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 it can 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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75 /*-----------------------------------------------------------
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76 * Implementation of functions defined in portable.h for the Atmel ARM7 port.
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77 *----------------------------------------------------------*/
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80 /* Standard includes. */
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83 /* Scheduler includes. */
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84 #include "FreeRTOS.h"
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87 /* Constants required to setup the initial stack. */
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88 #define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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89 #define portTHUMB_MODE_BIT ( ( portSTACK_TYPE ) 0x20 )
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90 #define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 )
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92 /* Constants required to setup the PIT. */
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93 #define portPIT_CLOCK_DIVISOR ( ( unsigned long ) 16 )
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94 #define portPIT_COUNTER_VALUE ( ( ( configCPU_CLOCK_HZ / portPIT_CLOCK_DIVISOR ) / 1000UL ) * portTICK_RATE_MS )
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96 /* Constants required to handle critical sections. */
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97 #define portNO_CRITICAL_NESTING ( ( unsigned long ) 0 )
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100 #define portINT_LEVEL_SENSITIVE 0
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101 #define portPIT_ENABLE ( ( unsigned short ) 0x1 << 24 )
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102 #define portPIT_INT_ENABLE ( ( unsigned short ) 0x1 << 25 )
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103 /*-----------------------------------------------------------*/
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105 /* Setup the PIT to generate the tick interrupts. */
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106 static void prvSetupTimerInterrupt( void );
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108 /* ulCriticalNesting will get set to zero when the first task starts. It
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109 cannot be initialised to 0 as this will cause interrupts to be enabled
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110 during the kernel initialisation process. */
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111 unsigned long ulCriticalNesting = ( unsigned long ) 9999;
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113 /*-----------------------------------------------------------*/
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116 * Initialise the stack of a task to look exactly as if a call to
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117 * portSAVE_CONTEXT had been called.
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119 * See header file for description.
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121 portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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123 portSTACK_TYPE *pxOriginalTOS;
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125 pxOriginalTOS = pxTopOfStack;
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127 /* To ensure asserts in tasks.c don't fail, although in this case the assert
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128 is not really required. */
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131 /* Setup the initial stack of the task. The stack is set exactly as
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132 expected by the portRESTORE_CONTEXT() macro. */
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134 /* First on the stack is the return address - which in this case is the
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135 start of the task. The offset is added to make the return address appear
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136 as it would within an IRQ ISR. */
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137 *pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
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140 *pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */
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142 *pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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144 *pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */
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146 *pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */
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148 *pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */
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150 *pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */
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152 *pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */
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154 *pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */
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156 *pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */
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158 *pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */
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160 *pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */
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162 *pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */
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164 *pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */
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166 *pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */
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169 /* When the task starts is will expect to find the function parameter in
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171 *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
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174 /* The status register is set for system mode, with interrupts enabled. */
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175 *pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR;
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177 if( ( ( unsigned long ) pxCode & 0x01UL ) != 0x00UL )
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179 /* We want the task to start in thumb mode. */
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180 *pxTopOfStack |= portTHUMB_MODE_BIT;
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185 /* 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_NESTING;
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190 return pxTopOfStack;
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192 /*-----------------------------------------------------------*/
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194 portBASE_TYPE xPortStartScheduler( void )
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196 extern void vPortStartFirstTask( void );
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198 /* Start the timer that generates the tick ISR. Interrupts are disabled
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200 prvSetupTimerInterrupt();
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202 /* Start the first task. */
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203 vPortStartFirstTask();
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205 /* Should not get here! */
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208 /*-----------------------------------------------------------*/
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210 void vPortEndScheduler( void )
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212 /* It is unlikely that the ARM port will require this function as there
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213 is nothing to return to. */
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215 /*-----------------------------------------------------------*/
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217 #if configUSE_PREEMPTION == 0
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219 /* The cooperative scheduler requires a normal IRQ service routine to
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220 simply increment the system tick. */
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221 static __arm __irq void vPortNonPreemptiveTick( void );
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222 static __arm __irq void vPortNonPreemptiveTick( void )
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224 unsigned long ulDummy;
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226 /* Increment the tick count - which may wake some tasks but as the
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227 preemptive scheduler is not being used any woken task is not given
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228 processor time no matter what its priority. */
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229 vTaskIncrementTick();
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231 /* Clear the PIT interrupt. */
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232 ulDummy = AT91C_BASE_PITC->PITC_PIVR;
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234 /* End the interrupt in the AIC. */
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235 AT91C_BASE_AIC->AIC_EOICR = ulDummy;
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240 /* Currently the IAR port requires the preemptive tick function to be
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241 defined in an asm file. */
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245 /*-----------------------------------------------------------*/
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247 static void prvSetupTimerInterrupt( void )
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249 AT91PS_PITC pxPIT = AT91C_BASE_PITC;
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251 /* Setup the AIC for PIT interrupts. The interrupt routine chosen depends
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252 on whether the preemptive or cooperative scheduler is being used. */
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253 #if configUSE_PREEMPTION == 0
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255 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_SYS, AT91C_AIC_PRIOR_HIGHEST, portINT_LEVEL_SENSITIVE, ( void (*)(void) ) vPortNonPreemptiveTick );
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259 extern void ( vPortPreemptiveTick )( void );
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260 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_SYS, AT91C_AIC_PRIOR_HIGHEST, portINT_LEVEL_SENSITIVE, ( void (*)(void) ) vPortPreemptiveTick );
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264 /* Configure the PIT period. */
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265 pxPIT->PITC_PIMR = portPIT_ENABLE | portPIT_INT_ENABLE | portPIT_COUNTER_VALUE;
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267 /* Enable the interrupt. Global interrupts are disables at this point so
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269 AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_SYS );
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271 /*-----------------------------------------------------------*/
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273 void vPortEnterCritical( void )
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275 /* Disable interrupts first! */
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276 __disable_interrupt();
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278 /* Now interrupts are disabled ulCriticalNesting can be accessed
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279 directly. Increment ulCriticalNesting to keep a count of how many times
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280 portENTER_CRITICAL() has been called. */
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281 ulCriticalNesting++;
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283 /*-----------------------------------------------------------*/
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285 void vPortExitCritical( void )
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287 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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289 /* Decrement the nesting count as we are leaving a critical section. */
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290 ulCriticalNesting--;
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292 /* If the nesting level has reached zero then interrupts should be
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294 if( ulCriticalNesting == portNO_CRITICAL_NESTING )
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296 __enable_interrupt();
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300 /*-----------------------------------------------------------*/
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