2 FreeRTOS V8.2.0 - Copyright (C) 2015 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 ***************************************************************************
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14 >>! NOTE: The modification to the GPL is included to allow you to !<<
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15 >>! distribute a combined work that includes FreeRTOS without being !<<
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16 >>! obliged to provide the source code for proprietary components !<<
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17 >>! outside of the FreeRTOS kernel. !<<
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18 ***************************************************************************
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20 FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY
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21 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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22 FOR A PARTICULAR PURPOSE. Full license text is available on the following
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23 link: http://www.freertos.org/a00114.html
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25 ***************************************************************************
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27 * FreeRTOS provides completely free yet professionally developed, *
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28 * robust, strictly quality controlled, supported, and cross *
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29 * platform software that is more than just the market leader, it *
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30 * is the industry's de facto standard. *
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32 * Help yourself get started quickly while simultaneously helping *
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33 * to support the FreeRTOS project by purchasing a FreeRTOS *
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34 * tutorial book, reference manual, or both: *
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35 * http://www.FreeRTOS.org/Documentation *
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37 ***************************************************************************
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39 http://www.FreeRTOS.org/FAQHelp.html - Having a problem? Start by reading
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40 the FAQ page "My application does not run, what could be wrong?". Have you
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41 defined configASSERT()?
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43 http://www.FreeRTOS.org/support - In return for receiving this top quality
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44 embedded software for free we request you assist our global community by
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45 participating in the support forum.
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47 http://www.FreeRTOS.org/training - Investing in training allows your team to
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48 be as productive as possible as early as possible. Now you can receive
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49 FreeRTOS training directly from Richard Barry, CEO of Real Time Engineers
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50 Ltd, and the world's leading authority on the world's leading RTOS.
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52 http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
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53 including FreeRTOS+Trace - an indispensable productivity tool, a DOS
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54 compatible FAT file system, and our tiny thread aware UDP/IP stack.
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56 http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
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57 Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.
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59 http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
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60 Integrity Systems ltd. to sell under the OpenRTOS brand. Low cost OpenRTOS
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61 licenses offer ticketed support, indemnification and commercial middleware.
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63 http://www.SafeRTOS.com - High Integrity Systems also provide a safety
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64 engineered and independently SIL3 certified version for use in safety and
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65 mission critical applications that require provable dependability.
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70 /*-----------------------------------------------------------
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71 * Implementation of functions defined in portable.h for the Atmel ARM7 port.
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72 *----------------------------------------------------------*/
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75 /* Standard includes. */
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78 /* Scheduler includes. */
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79 #include "FreeRTOS.h"
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82 /* Constants required to setup the initial stack. */
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83 #define portINITIAL_SPSR ( ( StackType_t ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
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84 #define portTHUMB_MODE_BIT ( ( StackType_t ) 0x20 )
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85 #define portINSTRUCTION_SIZE ( ( StackType_t ) 4 )
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87 /* Constants required to setup the PIT. */
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88 #define portPIT_CLOCK_DIVISOR ( ( uint32_t ) 16 )
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89 #define portPIT_COUNTER_VALUE ( ( ( configCPU_CLOCK_HZ / portPIT_CLOCK_DIVISOR ) / 1000UL ) * portTICK_PERIOD_MS )
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91 /* Constants required to handle critical sections. */
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92 #define portNO_CRITICAL_NESTING ( ( uint32_t ) 0 )
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95 #define portINT_LEVEL_SENSITIVE 0
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96 #define portPIT_ENABLE ( ( uint16_t ) 0x1 << 24 )
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97 #define portPIT_INT_ENABLE ( ( uint16_t ) 0x1 << 25 )
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98 /*-----------------------------------------------------------*/
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100 /* Setup the PIT to generate the tick interrupts. */
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101 static void prvSetupTimerInterrupt( void );
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103 /* ulCriticalNesting will get set to zero when the first task starts. It
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104 cannot be initialised to 0 as this will cause interrupts to be enabled
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105 during the kernel initialisation process. */
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106 uint32_t ulCriticalNesting = ( uint32_t ) 9999;
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108 /*-----------------------------------------------------------*/
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111 * Initialise the stack of a task to look exactly as if a call to
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112 * portSAVE_CONTEXT had been called.
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114 * See header file for description.
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116 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
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118 StackType_t *pxOriginalTOS;
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120 pxOriginalTOS = pxTopOfStack;
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122 /* To ensure asserts in tasks.c don't fail, although in this case the assert
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123 is not really required. */
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126 /* Setup the initial stack of the task. The stack is set exactly as
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127 expected by the portRESTORE_CONTEXT() macro. */
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129 /* First on the stack is the return address - which in this case is the
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130 start of the task. The offset is added to make the return address appear
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131 as it would within an IRQ ISR. */
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132 *pxTopOfStack = ( StackType_t ) pxCode + portINSTRUCTION_SIZE;
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135 *pxTopOfStack = ( StackType_t ) 0xaaaaaaaa; /* R14 */
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137 *pxTopOfStack = ( StackType_t ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
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139 *pxTopOfStack = ( StackType_t ) 0x12121212; /* R12 */
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141 *pxTopOfStack = ( StackType_t ) 0x11111111; /* R11 */
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143 *pxTopOfStack = ( StackType_t ) 0x10101010; /* R10 */
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145 *pxTopOfStack = ( StackType_t ) 0x09090909; /* R9 */
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147 *pxTopOfStack = ( StackType_t ) 0x08080808; /* R8 */
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149 *pxTopOfStack = ( StackType_t ) 0x07070707; /* R7 */
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151 *pxTopOfStack = ( StackType_t ) 0x06060606; /* R6 */
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153 *pxTopOfStack = ( StackType_t ) 0x05050505; /* R5 */
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155 *pxTopOfStack = ( StackType_t ) 0x04040404; /* R4 */
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157 *pxTopOfStack = ( StackType_t ) 0x03030303; /* R3 */
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159 *pxTopOfStack = ( StackType_t ) 0x02020202; /* R2 */
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161 *pxTopOfStack = ( StackType_t ) 0x01010101; /* R1 */
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164 /* When the task starts is will expect to find the function parameter in
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166 *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
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169 /* The status register is set for system mode, with interrupts enabled. */
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170 *pxTopOfStack = ( StackType_t ) portINITIAL_SPSR;
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172 if( ( ( uint32_t ) pxCode & 0x01UL ) != 0x00UL )
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174 /* We want the task to start in thumb mode. */
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175 *pxTopOfStack |= portTHUMB_MODE_BIT;
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180 /* Interrupt flags cannot always be stored on the stack and will
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181 instead be stored in a variable, which is then saved as part of the
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183 *pxTopOfStack = portNO_CRITICAL_NESTING;
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185 return pxTopOfStack;
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187 /*-----------------------------------------------------------*/
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189 BaseType_t xPortStartScheduler( void )
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191 extern void vPortStartFirstTask( void );
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193 /* Start the timer that generates the tick ISR. Interrupts are disabled
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195 prvSetupTimerInterrupt();
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197 /* Start the first task. */
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198 vPortStartFirstTask();
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200 /* Should not get here! */
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203 /*-----------------------------------------------------------*/
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205 void vPortEndScheduler( void )
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207 /* It is unlikely that the ARM port will require this function as there
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208 is nothing to return to. */
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210 /*-----------------------------------------------------------*/
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212 #if configUSE_PREEMPTION == 0
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214 /* The cooperative scheduler requires a normal IRQ service routine to
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215 simply increment the system tick. */
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216 static __arm __irq void vPortNonPreemptiveTick( void );
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217 static __arm __irq void vPortNonPreemptiveTick( void )
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221 /* Increment the tick count - which may wake some tasks but as the
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222 preemptive scheduler is not being used any woken task is not given
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223 processor time no matter what its priority. */
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224 xTaskIncrementTick();
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226 /* Clear the PIT interrupt. */
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227 ulDummy = AT91C_BASE_PITC->PITC_PIVR;
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229 /* End the interrupt in the AIC. */
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230 AT91C_BASE_AIC->AIC_EOICR = ulDummy;
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235 /* Currently the IAR port requires the preemptive tick function to be
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236 defined in an asm file. */
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240 /*-----------------------------------------------------------*/
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242 static void prvSetupTimerInterrupt( void )
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244 AT91PS_PITC pxPIT = AT91C_BASE_PITC;
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246 /* Setup the AIC for PIT interrupts. The interrupt routine chosen depends
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247 on whether the preemptive or cooperative scheduler is being used. */
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248 #if configUSE_PREEMPTION == 0
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250 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_SYS, AT91C_AIC_PRIOR_HIGHEST, portINT_LEVEL_SENSITIVE, ( void (*)(void) ) vPortNonPreemptiveTick );
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254 extern void ( vPortPreemptiveTick )( void );
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255 AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_SYS, AT91C_AIC_PRIOR_HIGHEST, portINT_LEVEL_SENSITIVE, ( void (*)(void) ) vPortPreemptiveTick );
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259 /* Configure the PIT period. */
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260 pxPIT->PITC_PIMR = portPIT_ENABLE | portPIT_INT_ENABLE | portPIT_COUNTER_VALUE;
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262 /* Enable the interrupt. Global interrupts are disables at this point so
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264 AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_SYS );
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266 /*-----------------------------------------------------------*/
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268 void vPortEnterCritical( void )
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270 /* Disable interrupts first! */
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271 __disable_interrupt();
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273 /* Now interrupts are disabled ulCriticalNesting can be accessed
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274 directly. Increment ulCriticalNesting to keep a count of how many times
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275 portENTER_CRITICAL() has been called. */
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276 ulCriticalNesting++;
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278 /*-----------------------------------------------------------*/
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280 void vPortExitCritical( void )
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282 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
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284 /* Decrement the nesting count as we are leaving a critical section. */
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285 ulCriticalNesting--;
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287 /* If the nesting level has reached zero then interrupts should be
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289 if( ulCriticalNesting == portNO_CRITICAL_NESTING )
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291 __enable_interrupt();
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295 /*-----------------------------------------------------------*/
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