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Update XMOS xcore.ai port to be compatible with v11.x (FreeRTOS#1096)
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* Fix kexcept function

* Create dummy pxCurrentTCBs for xcore.ai port

* Additional commentary

* Add a layer of indirection to cope with singlecore

* Clarify use of _DoException
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ACascarino authored Jun 27, 2024
1 parent 9e83829 commit 17dfd0f
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Showing 2 changed files with 36 additions and 8 deletions.
35 changes: 33 additions & 2 deletions portable/ThirdParty/xClang/XCOREAI/port.c
Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,15 @@ static hwtimer_t xKernelTimer;

uint32_t ulPortYieldRequired[ portMAX_CORE_COUNT ] = { pdFALSE };

/* When this port was designed, it was assumed that pxCurrentTCBs would always
exist and that it would always be an array containing pointers to the current
TCBs for each core. In v11, this is not the case; if we are only running one
core, the symbol is pxCurrentTCB instead. Therefore, this port adds a layer
of indirection - we populate this pointer-to-pointer in the RTOS kernel entry
function below. This makes this port agnostic to whether it is running on SMP
or singlecore RTOS. */
void ** xcorePvtTCBContainer;

/*-----------------------------------------------------------*/

void vIntercoreInterruptISR( void )
Expand Down Expand Up @@ -140,15 +149,37 @@ DEFINE_RTOS_KERNEL_ENTRY( void, vPortStartSchedulerOnCore, void )
}
#endif

/* Populate the TCBContainer depending on whether we're singlecore or SMP */
#if ( configNUMBER_OF_CORES == 1 )
{
asm volatile (
"ldaw %0, dp[pxCurrentTCB]\n\t"
: "=r"(xcorePvtTCBContainer)
: /* no inputs */
: /* no clobbers */
);
}
#else
{
asm volatile (
"ldaw %0, dp[pxCurrentTCBs]\n\t"
: "=r"(xcorePvtTCBContainer)
: /* no inputs */
: /* no clobbers */
);
}

#endif

debug_printf( "FreeRTOS Core %d initialized\n", xCoreID );

/*
* Restore the context of the first thread
* to run and jump into it.
*/
asm volatile (
"mov r6, %0\n\t" /* R6 must be the FreeRTOS core ID*/
"ldaw r5, dp[pxCurrentTCBs]\n\t" /* R5 must be the TCB list which is indexed by R6 */
"mov r6, %0\n\t" /* R6 must be the FreeRTOS core ID. In singlecore this is always 0. */
"ldw r5, dp[xcorePvtTCBContainer]\n\t" /* R5 must be the TCB list which is indexed by R6 */
"bu _freertos_restore_ctx\n\t"
: /* no outputs */
: "r" ( xCoreID )
Expand Down
9 changes: 3 additions & 6 deletions portable/ThirdParty/xClang/XCOREAI/portasm.S
Original file line number Diff line number Diff line change
Expand Up @@ -14,11 +14,8 @@ rest of the ISR callback functions. */
.issue_mode dual
.cc_top kexcept.function, kexcept
kexcept:
ldc r11, 0x0008
shl r11, r11, 16
ldc r9, 0x0080
or r11, r11, r9
bau r11 //_TrapHandler is at 0x00080080. TODO: Is it always? Why can't I access the symbol _TrapHandler?
bu _DoException /* This symbol is generated by the toolchain and */
/* provides graceful exception handling */

_yield:
{set sp, r4 /* Restore the task's SP to save the rest of its context. */
Expand Down Expand Up @@ -123,7 +120,7 @@ _yield_continue:
ldaw r11, sp[37]}
vstc r11[0]
#endif
ldaw r5, dp[pxCurrentTCBs] /* Get the current TCB array into r5. */
ldw r5, dp[xcorePvtTCBContainer]
ldw r1, r5[r0] /* Get this core's current TCB pointer into r1. */
stw r4, r1[0x0] /* Save the current task's SP to the first */
/* word (top of stack) in the current TCB. */
Expand Down

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