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Improvements to the Cortex-M ports:

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- Clear the SysTick current value register before starting the SysTick (only required if something uses SysTick before starting the scheduler).
- Ensure atomic operations are thread safe by executing clrex in the context switch.
This commit is contained in:
Richard Barry 2016-06-27 13:13:05 +00:00
parent 6c975cd46a
commit c296e2cff8
23 changed files with 139 additions and 40 deletions
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13
FreeRTOS/Source/portable/GCC/ARM_CM0/port.c
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@ -76,8 +76,9 @@
#include "task.h"
/* Constants required to manipulate the NVIC. */
#define portNVIC_SYSTICK_CTRL ( ( volatile uint32_t *) 0xe000e010 )
#define portNVIC_SYSTICK_LOAD ( ( volatile uint32_t *) 0xe000e014 )
#define portNVIC_SYSTICK_CTRL ( ( volatile uint32_t * ) 0xe000e010 )
#define portNVIC_SYSTICK_LOAD ( ( volatile uint32_t * ) 0xe000e014 )
#define portNVIC_SYSTICK_CURRENT_VALUE ( ( volatile uint32_t * ) 0xe000e018 )
#define portNVIC_INT_CTRL ( ( volatile uint32_t *) 0xe000ed04 )
#define portNVIC_SYSPRI2 ( ( volatile uint32_t *) 0xe000ed20 )
#define portNVIC_SYSTICK_CLK 0x00000004
@ -310,7 +311,7 @@ void xPortPendSVHandler( void )
" mov r5, r9 \n"
" mov r6, r10 \n"
" mov r7, r11 \n"
" stmia r0!, {r4-r7} \n"
" stmia r0!, {r4-r7} \n"
" \n"
" push {r3, r14} \n"
" cpsid i \n"
@ -330,7 +331,7 @@ void xPortPendSVHandler( void )
" msr psp, r0 \n" /* Remember the new top of stack for the task. */
" \n"
" sub r0, r0, #32 \n" /* Go back for the low registers that are not automatically restored. */
" ldmia r0!, {r4-r7} \n" /* Pop low registers. */
" ldmia r0!, {r4-r7} \n" /* Pop low registers. */
" \n"
" bx r3 \n"
" \n"
@ -363,6 +364,10 @@ uint32_t ulPreviousMask;
*/
void prvSetupTimerInterrupt( void )
{
/* Stop and reset the SysTick. */
*(portNVIC_SYSTICK_CTRL) = 0UL;
*(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL;
/* Configure SysTick to interrupt at the requested rate. */
*(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;
*(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;