port.c

STM32 FreeRTOS v5.2移植源代码

	/* Because FreeRTOS is not supposed to run with nested interrupts, put all OS
	calls in a critical section . */
	portENTER_CRITICAL();
		vTaskIncrementTick();
	portEXIT_CRITICAL();

	/* Restore the context of the "elected task". */
	portRESTORE_CONTEXT_OS_INT();
}
/*-----------------------------------------------------------*/

__attribute__((__naked__)) void SCALLYield( void )
{
	/* Save the context of the interrupted task. */
	portSAVE_CONTEXT_SCALL();
	vTaskSwitchContext();
	portRESTORE_CONTEXT_SCALL();
}
/*-----------------------------------------------------------*/

/* The code generated by the GCC compiler uses the stack in different ways at
different optimisation levels.  The interrupt flags can therefore not always
be saved to the stack.  Instead the critical section nesting level is stored
in a variable, which is then saved as part of the stack context. */
__attribute__((__noinline__)) void vPortEnterCritical( void )
{
	/* Disable interrupts */
	portDISABLE_INTERRUPTS();

	/* Now interrupts are disabled ulCriticalNesting can be accessed
	 directly.  Increment ulCriticalNesting to keep a count of how many times
	 portENTER_CRITICAL() has been called. */
	ulCriticalNesting++;
}
/*-----------------------------------------------------------*/

__attribute__((__noinline__)) void vPortExitCritical( void )
{
	if(ulCriticalNesting > portNO_CRITICAL_NESTING)
	{
		ulCriticalNesting--;
		if( ulCriticalNesting == portNO_CRITICAL_NESTING )
		{
			/* Enable all interrupt/exception. */
			portENABLE_INTERRUPTS();
		}
	}
}
/*-----------------------------------------------------------*/

/*
 * Initialise the stack of a task to look exactly as if a call to
 * portSAVE_CONTEXT had been called.
 *
 * See header file for description.
 */
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
	/* Setup the initial stack of the task.  The stack is set exactly as
	expected by the portRESTORE_CONTEXT() macro. */

	/* When the task starts, it will expect to find the function parameter in R12. */
	pxTopOfStack--;
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x08080808;					/* R8 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x09090909;					/* R9 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x0A0A0A0A;					/* R10 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x0B0B0B0B;					/* R11 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) pvParameters;					/* R12 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0xDEADBEEF;					/* R14/LR */
	*pxTopOfStack-- = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE; /* R15/PC */
	*pxTopOfStack-- = ( portSTACK_TYPE ) portINITIAL_SR;				/* SR */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0xFF0000FF;					/* R0 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x01010101;					/* R1 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x02020202;					/* R2 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x03030303;					/* R3 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x04040404;					/* R4 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x05050505;					/* R5 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x06060606;					/* R6 */
	*pxTopOfStack-- = ( portSTACK_TYPE ) 0x07070707;					/* R7 */
	*pxTopOfStack = ( portSTACK_TYPE ) portNO_CRITICAL_NESTING;			/* ulCriticalNesting */

	return pxTopOfStack;
}
/*-----------------------------------------------------------*/

portBASE_TYPE xPortStartScheduler( void )
{
	/* Start the timer that generates the tick ISR.  Interrupts are disabled
	here already. */
	prvSetupTimerInterrupt();

	/* Start the first task. */
	portRESTORE_CONTEXT();

	/* Should not get here! */
	return 0;
}
/*-----------------------------------------------------------*/

void vPortEndScheduler( void )
{
	/* It is unlikely that the AVR32 port will require this function as there
	is nothing to return to.  */
}
/*-----------------------------------------------------------*/

/* Schedule the COUNT&COMPARE match interrupt in (configCPU_CLOCK_HZ/configTICK_RATE_HZ)
clock cycles from now. */
#if( configTICK_USE_TC==0 )
	static void prvScheduleFirstTick(void)
	{
		unsigned long lCycles;

		lCycles = Get_system_register(AVR32_COUNT);
		lCycles += (configCPU_CLOCK_HZ/configTICK_RATE_HZ);
		// If lCycles ends up to be 0, make it 1 so that the COMPARE and exception
		// generation feature does not get disabled.
		if(0 == lCycles)
		{
			lCycles++;
		}
		Set_system_register(AVR32_COMPARE, lCycles);
	}
	
	__attribute__((__noinline__)) static void prvScheduleNextTick(void)
	{
		unsigned long lCycles, lCount;

		lCycles = Get_system_register(AVR32_COMPARE);
		lCycles += (configCPU_CLOCK_HZ/configTICK_RATE_HZ);
		// If lCycles ends up to be 0, make it 1 so that the COMPARE and exception
		// generation feature does not get disabled.
		if(0 == lCycles)
		{
			lCycles++;
		}
		lCount = Get_system_register(AVR32_COUNT);
		if( lCycles < lCount )
		{		// We missed a tick, recover for the next.
			lCycles += (configCPU_CLOCK_HZ/configTICK_RATE_HZ);
		}
		Set_system_register(AVR32_COMPARE, lCycles);
	}
#else
	__attribute__((__noinline__)) static void prvClearTcInt(void)
	{
		AVR32_TC.channel[configTICK_TC_CHANNEL].sr;
	}
#endif
/*-----------------------------------------------------------*/

/* Setup the timer to generate the tick interrupts. */
static void prvSetupTimerInterrupt(void)
{
#if( configTICK_USE_TC==1 )

	volatile avr32_tc_t *tc = &AVR32_TC;

	// Options for waveform genration.
	tc_waveform_opt_t waveform_opt =
	{
	.channel  = configTICK_TC_CHANNEL,             /* Channel selection. */

	.bswtrg   = TC_EVT_EFFECT_NOOP,                /* Software trigger effect on TIOB. */
	.beevt    = TC_EVT_EFFECT_NOOP,                /* External event effect on TIOB. */
	.bcpc     = TC_EVT_EFFECT_NOOP,                /* RC compare effect on TIOB. */
	.bcpb     = TC_EVT_EFFECT_NOOP,                /* RB compare effect on TIOB. */

	.aswtrg   = TC_EVT_EFFECT_NOOP,                /* Software trigger effect on TIOA. */
	.aeevt    = TC_EVT_EFFECT_NOOP,                /* External event effect on TIOA. */
	.acpc     = TC_EVT_EFFECT_NOOP,                /* RC compare effect on TIOA: toggle. */
	.acpa     = TC_EVT_EFFECT_NOOP,                /* RA compare effect on TIOA: toggle (other possibilities are none, set and clear). */

	.wavsel   = TC_WAVEFORM_SEL_UP_MODE_RC_TRIGGER,/* Waveform selection: Up mode without automatic trigger on RC compare. */
	.enetrg   = FALSE,                             /* External event trigger enable. */
	.eevt     = 0,                                 /* External event selection. */
	.eevtedg  = TC_SEL_NO_EDGE,                    /* External event edge selection. */
	.cpcdis   = FALSE,                             /* Counter disable when RC compare. */
	.cpcstop  = FALSE,                             /* Counter clock stopped with RC compare. */

	.burst    = FALSE,                             /* Burst signal selection. */
	.clki     = FALSE,                             /* Clock inversion. */
	.tcclks   = TC_CLOCK_SOURCE_TC2                /* Internal source clock 2. */
	};

	tc_interrupt_t tc_interrupt =
	{
		.etrgs=0,
		.ldrbs=0,
		.ldras=0,
		.cpcs =1,
		.cpbs =0,
		.cpas =0,
		.lovrs=0,
		.covfs=0,
	};

#endif

	/* Disable all interrupt/exception. */
	portDISABLE_INTERRUPTS();

	/* Register the compare interrupt handler to the interrupt controller and
	enable the compare interrupt. */

	#if( configTICK_USE_TC==1 )
	{
		INTC_register_interrupt(&vTick, configTICK_TC_IRQ, INT0);

		/* Initialize the timer/counter. */
		tc_init_waveform(tc, &waveform_opt);

		/* Set the compare triggers.
		Remember TC counter is 16-bits, so counting second is not possible!
		That's why we configure it to count ms. */
		tc_write_rc( tc, configTICK_TC_CHANNEL, ( configPBA_CLOCK_HZ / 4) / configTICK_RATE_HZ );

		tc_configure_interrupts( tc, configTICK_TC_CHANNEL, &tc_interrupt );

		/* Start the timer/counter. */
		tc_start(tc, configTICK_TC_CHANNEL);
	}
	#else
	{
		INTC_register_interrupt(&vTick, AVR32_CORE_COMPARE_IRQ, INT0);
		prvScheduleFirstTick();
	}
	#endif
}