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14 * The above copyright notice and this permission notice shall be included in all
15 * copies or substantial portions of the Software.
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22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
30 * Implementation of functions defined in portable.h for the ARM CM7 port.
41 …#error This port can only be used when the project options are configured to enable hardware float…
51 /* Constants required to manipulate the core. Registers first... */
57 /* ...then bits in the registers. */
70 /* Constants used to check the installation of the FreeRTOS interrupt handlers. */
75 /* Constants required to check the validity of an interrupt priority. */
85 /* Masks off all bits but the VECTACTIVE bits in the ICSR register. */
88 /* Constants required to manipulate the VFP. */
92 /* Constants required to set up the initial stack. */
96 /* The systick is a 24-bit counter. */
99 /* A fiddle factor to estimate the number of SysTick counts that would have
100 * occurred while the SysTick counter is stopped during tickless idle
104 /* For strict compliance with the Cortex-M spec the task start address should
105 * have bit-0 clear, as it is loaded into the PC on exit from an ISR. */
108 /* Let the user override the default SysTick clock rate. If defined by the
109 * user, this symbol must equal the SysTick clock rate when the CLK bit is 0 in the
113 /* Ensure the SysTick is clocked at the same frequency as the core. */
116 /* Select the option to clock SysTick not at the same frequency as the core. */
121 * Setup the timer to generate the tick interrupts. The implementation in this
122 * file is weak to allow application writers to change the timer used to
123 * generate the tick interrupt.
138 * Turn the VFP on.
154 /* Each task maintains its own interrupt status in the critical nesting
159 * The number of SysTick increments that make up one tick period.
166 * The maximum number of tick periods that can be suppressed is limited by the
167 * 24 bit resolution of the SysTick timer.
174 * Compensate for the CPU cycles that pass while the SysTick is stopped (low
182 * Used by the portASSERT_IF_INTERRUPT_PRIORITY_INVALID() macro to ensure
201 /* Simulate the stack frame as it would be created by a context switch in pxPortInitialiseStack()
204 /* Offset added to account for the way the MCU uses the stack on entry/exit in pxPortInitialiseStack()
236 * defined, then stop here so application writers can catch the error. */ in prvTaskExitError()
251 /* An application can install FreeRTOS interrupt handlers in one of the in xPortStartScheduler()
253 * 1. Direct Routing - Install the functions vPortSVCHandler and in xPortStartScheduler()
267 /* Validate that the application has correctly installed the FreeRTOS in xPortStartScheduler()
268 * handlers for SVCall and PendSV interrupts. We do not check the in xPortStartScheduler()
269 * installation of the SysTick handler because the application may in xPortStartScheduler()
270 * choose to drive the RTOS tick using a timer other than the SysTick in xPortStartScheduler()
271 * timer by overriding the weak function vPortSetupTimerInterrupt(). in xPortStartScheduler()
273 * Assertion failures here indicate incorrect installation of the in xPortStartScheduler()
274 * FreeRTOS handlers. For help installing the FreeRTOS handlers, see in xPortStartScheduler()
277 * Systems with a configurable address for the interrupt vector table in xPortStartScheduler()
279 * VTOR is not set correctly to point to the application's vector table. */ in xPortStartScheduler()
292 /* Determine the maximum priority from which ISR safe FreeRTOS API in xPortStartScheduler()
297 * Save the interrupt priority value that is about to be clobbered. */ in xPortStartScheduler()
300 /* Determine the number of priority bits available. First write to all in xPortStartScheduler()
304 /* Read the value back to see how many bits stuck. */ in xPortStartScheduler()
307 /* Use the same mask on the maximum system call priority. */ in xPortStartScheduler()
310 /* Check that the maximum system call priority is nonzero after in xPortStartScheduler()
311 * accounting for the number of priority bits supported by the in xPortStartScheduler()
312 * hardware. A priority of 0 is invalid because setting the BASEPRI in xPortStartScheduler()
318 /* Check that the bits not implemented in hardware are zero in in xPortStartScheduler()
322 /* Calculate the maximum acceptable priority group value for the number in xPortStartScheduler()
333 /* When the hardware implements 8 priority bits, there is no way for in xPortStartScheduler()
334 * the software to configure PRIGROUP to not have sub-priorities. As in xPortStartScheduler()
335 * a result, the least significant bit is always used for sub-priority in xPortStartScheduler()
341 * are at the same preemption priority. This may appear confusing as in xPortStartScheduler()
345 * to 4, this confusion does not happen and the behaviour remains the same. in xPortStartScheduler()
347 * The following assert ensures that the sub-priority bit in the in xPortStartScheduler()
348 * configMAX_SYSCALL_INTERRUPT_PRIORITY is clear to avoid the above mentioned in xPortStartScheduler()
358 /* Shift the priority group value back to its position within the AIRCR in xPortStartScheduler()
363 /* Restore the clobbered interrupt priority register to its original in xPortStartScheduler()
369 /* Make PendSV and SysTick the lowest priority interrupts, and make SVCall in xPortStartScheduler()
370 * the highest priority. */ in xPortStartScheduler()
375 /* Start the timer that generates the tick ISR. Interrupts are disabled in xPortStartScheduler()
379 /* Initialise the critical nesting count ready for the first task. */ in xPortStartScheduler()
382 /* Ensure the VFP is enabled - it should be anyway. */ in xPortStartScheduler()
388 /* Start the first task. */ in xPortStartScheduler()
409 /* This is not the interrupt safe version of the enter critical function so in vPortEnterCritical()
412 * the critical nesting count is 1 to protect against recursive calls if the in vPortEnterCritical()
435 /* The SysTick runs at the lowest interrupt priority, so when this interrupt in xPortSysTickHandler()
437 * save and then restore the interrupt mask value as its value is already in xPortSysTickHandler()
442 /* Increment the RTOS tick. */ in xPortSysTickHandler()
448 * the PendSV interrupt. Pend the PendSV interrupt. */ in xPortSysTickHandler()
467 /* Make sure the SysTick reload value does not overflow the counter. */ in vPortSuppressTicksAndSleep()
473 /* Enter a critical section but don't use the taskENTER_CRITICAL() in vPortSuppressTicksAndSleep()
479 /* If a context switch is pending or a task is waiting for the scheduler in vPortSuppressTicksAndSleep()
480 * to be unsuspended then abandon the low power entry. */ in vPortSuppressTicksAndSleep()
483 /* Re-enable interrupts - see comments above the __disable_interrupt() in vPortSuppressTicksAndSleep()
489 /* Stop the SysTick momentarily. The time the SysTick is stopped for in vPortSuppressTicksAndSleep()
490 * is accounted for as best it can be, but using the tickless mode will in vPortSuppressTicksAndSleep()
491 * inevitably result in some tiny drift of the time maintained by the in vPortSuppressTicksAndSleep()
495 /* Use the SysTick current-value register to determine the number of in vPortSuppressTicksAndSleep()
496 * SysTick decrements remaining until the next tick interrupt. If the in vPortSuppressTicksAndSleep()
498 * ulTimerCountsForOneTick decrements remaining, not zero, because the in vPortSuppressTicksAndSleep()
499 * SysTick requests the interrupt when decrementing from 1 to 0. */ in vPortSuppressTicksAndSleep()
507 /* Calculate the reload value required to wait xExpectedIdleTime in vPortSuppressTicksAndSleep()
509 * way through the first tick period. But if the SysTick IRQ is now in vPortSuppressTicksAndSleep()
510 * pending, then clear the IRQ, suppressing the first tick, and correct in vPortSuppressTicksAndSleep()
511 * the reload value to reflect that the second tick period is already in vPortSuppressTicksAndSleep()
512 * underway. The expected idle time is always at least two ticks. */ in vPortSuppressTicksAndSleep()
526 /* Set the new reload value. */ in vPortSuppressTicksAndSleep()
529 /* Clear the SysTick count flag and set the count value back to in vPortSuppressTicksAndSleep()
539 * should not be executed again. However, the original expected idle in vPortSuppressTicksAndSleep()
553 /* Re-enable interrupts to allow the interrupt that brought the MCU in vPortSuppressTicksAndSleep()
555 * the __disable_interrupt() call above. */ in vPortSuppressTicksAndSleep()
560 /* Disable interrupts again because the clock is about to be stopped in vPortSuppressTicksAndSleep()
561 * and interrupts that execute while the clock is stopped will increase in vPortSuppressTicksAndSleep()
562 * any slippage between the time maintained by the RTOS and calendar in vPortSuppressTicksAndSleep()
568 /* Disable the SysTick clock without reading the in vPortSuppressTicksAndSleep()
569 * portNVIC_SYSTICK_CTRL_REG register to ensure the in vPortSuppressTicksAndSleep()
571 * the time the SysTick is stopped for is accounted for as best it can in vPortSuppressTicksAndSleep()
572 * be, but using the tickless mode will inevitably result in some tiny in vPortSuppressTicksAndSleep()
573 * drift of the time maintained by the kernel with respect to calendar in vPortSuppressTicksAndSleep()
577 /* Determine whether the SysTick has already counted to zero. */ in vPortSuppressTicksAndSleep()
582 /* The tick interrupt ended the sleep (or is now pending), and in vPortSuppressTicksAndSleep()
584 * with whatever remains of the new tick period. */ in vPortSuppressTicksAndSleep()
588 * underflowed because the post sleep hook did something in vPortSuppressTicksAndSleep()
589 * that took too long or because the SysTick current-value register in vPortSuppressTicksAndSleep()
598 /* As the pending tick will be processed as soon as this in vPortSuppressTicksAndSleep()
599 * function exits, the tick value maintained by the tick is stepped in vPortSuppressTicksAndSleep()
600 * forward by one less than the time spent waiting. */ in vPortSuppressTicksAndSleep()
605 /* Something other than the tick interrupt ended the sleep. */ in vPortSuppressTicksAndSleep()
607 /* Use the SysTick current-value register to determine the in vPortSuppressTicksAndSleep()
608 * number of SysTick decrements remaining until the expected idle in vPortSuppressTicksAndSleep()
613 /* If the SysTick is not using the core clock, the current- in vPortSuppressTicksAndSleep()
614 * value register might still be zero here. In that case, the in vPortSuppressTicksAndSleep()
615 * SysTick didn't load from the reload register, and there are in vPortSuppressTicksAndSleep()
616 * ulReloadValue decrements remaining in the expected idle in vPortSuppressTicksAndSleep()
625 /* Work out how long the sleep lasted rounded to complete tick in vPortSuppressTicksAndSleep()
626 * periods (not the ulReload value which accounted for part in vPortSuppressTicksAndSleep()
630 /* How many complete tick periods passed while the processor in vPortSuppressTicksAndSleep()
634 /* The reload value is set to whatever fraction of a single tick in vPortSuppressTicksAndSleep()
641 * the SysTick is not using the core clock, temporarily configure it to in vPortSuppressTicksAndSleep()
642 * use the core clock. This configuration forces the SysTick to load in vPortSuppressTicksAndSleep()
643 * from portNVIC_SYSTICK_LOAD_REG immediately instead of at the next in vPortSuppressTicksAndSleep()
644 * cycle of the other clock. Then portNVIC_SYSTICK_LOAD_REG is ready in vPortSuppressTicksAndSleep()
645 * to receive the standard value immediately. */ in vPortSuppressTicksAndSleep()
654 /* The temporary usage of the core clock has served its purpose, in vPortSuppressTicksAndSleep()
655 * as described above. Resume usage of the other clock. */ in vPortSuppressTicksAndSleep()
660 /* The partial tick period already ended. Be sure the SysTick in vPortSuppressTicksAndSleep()
670 /* Step the tick to account for any tick periods that elapsed. */ in vPortSuppressTicksAndSleep()
682 * Setup the systick timer to generate the tick interrupts at the required
687 /* Calculate the constants required to configure the tick interrupt. */ in vPortSetupTimerInterrupt()
696 /* Stop and clear the SysTick. */ in vPortSetupTimerInterrupt()
700 /* Configure SysTick to interrupt at the requested rate. */ in vPortSetupTimerInterrupt()
713 /* Obtain the number of the currently executing interrupt. */ in vPortValidateInterruptPriority()
716 /* Is the interrupt number a user defined interrupt? */ in vPortValidateInterruptPriority()
719 /* Look up the interrupt's priority. */ in vPortValidateInterruptPriority()
722 /* The following assertion will fail if a service routine (ISR) for in vPortValidateInterruptPriority()
730 * interrupt priorities, therefore the priority of the interrupt must in vPortValidateInterruptPriority()
734 * Interrupts that use the FreeRTOS API must not be left at their in vPortValidateInterruptPriority()
735 * default priority of zero as that is the highest possible priority, in vPortValidateInterruptPriority()
742 * The following links provide detailed information: in vPortValidateInterruptPriority()
748 /* Priority grouping: The interrupt controller (NVIC) allows the bits in vPortValidateInterruptPriority()
750 * define the interrupt's pre-emption priority bits and bits that define in vPortValidateInterruptPriority()
751 * the interrupt's sub-priority. For simplicity all bits must be defined in vPortValidateInterruptPriority()
752 * to be pre-emption priority bits. The following assertion will fail if in vPortValidateInterruptPriority()
753 * this is not the case (if some bits represent a sub-priority). in vPortValidateInterruptPriority()
755 * If the application only uses CMSIS libraries for interrupt in vPortValidateInterruptPriority()
756 * configuration then the correct setting can be achieved on all Cortex-M in vPortValidateInterruptPriority()
757 * devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the in vPortValidateInterruptPriority()