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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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6
FreeRTOS/Source/portable/GCC/ARM_CM3_MPU/port.c
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@ -89,6 +89,7 @@ task.h is included from an application file. */
/* Constants required to access and manipulate the NVIC. */
#define portNVIC_SYSTICK_CTRL_REG ( * ( ( volatile uint32_t * ) 0xe000e010 ) )
#define portNVIC_SYSTICK_LOAD_REG ( * ( ( volatile uint32_t * ) 0xe000e014 ) )
#define portNVIC_SYSTICK_CURRENT_VALUE_REG ( * ( ( volatile uint32_t * ) 0xe000e018 ) )
#define portNVIC_SYSPRI2_REG ( * ( ( volatile uint32_t * ) 0xe000ed20 ) )
#define portNVIC_SYSPRI1_REG ( * ( ( volatile uint32_t * ) 0xe000ed1c ) )
#define portNVIC_SYS_CTRL_STATE_REG ( * ( ( volatile uint32_t * ) 0xe000ed24 ) )
@ -449,6 +450,7 @@ void xPortPendSVHandler( void )
" mrs r1, control \n"
" stmdb r0!, {r1, r4-r11} \n" /* Save the remaining registers. */
" str r0, [r2] \n" /* Save the new top of stack into the first member of the TCB. */
" clrex \n" /* Ensure thread safety of atomic operations. */
" \n"
" stmdb sp!, {r3, r14} \n"
" mov r0, %0 \n"
@ -500,6 +502,10 @@ uint32_t ulDummy;
*/
static void prvSetupTimerInterrupt( void )
{
/* Reset the SysTick timer. */
portNVIC_SYSTICK_CTRL_REG = 0UL;
portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
/* Configure SysTick to interrupt at the requested rate. */
portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;