diff options
| -rw-r--r-- | core/cortex-m0/switch.S | 35 | ||||
| -rw-r--r-- | core/cortex-m0/task.c | 27 |
2 files changed, 36 insertions, 26 deletions
diff --git a/core/cortex-m0/switch.S b/core/cortex-m0/switch.S index 4b5ae23838..a58336b0c1 100644 --- a/core/cortex-m0/switch.S +++ b/core/cortex-m0/switch.S @@ -7,6 +7,8 @@ #include "config.h" +#define CPU_SCB_ICSR 0xe000ed04 + .text .syntax unified @@ -79,3 +81,36 @@ __task_start: movs r0, #1 @ set to EC_ERROR_UNKNOWN bx lr +/** + * SVC exception handler + */ +.global svc_handler +.thumb_func +svc_handler: + push {r3, lr} @ save link register and keep stack aligned + bl __svc_handler @ call svc handler helper + ldr r3,=current_task @ load the current task's address + ldr r1, [r3] @ load the current task + cmp r0, r1 @ compare with previous task returned by helper + beq svc_handler_return @ return if they are the same + bl __switchto @ context switch to the next task +svc_handler_return: + pop {r3, pc} @ return from exception or return to caller + +/** + * PendSVC exception handler + */ +.global pendsv_handler +.thumb_func +pendsv_handler: + push {r3, lr} @ save link register and keep stack aligned + ldr r0, =#CPU_SCB_ICSR @ load CPU_SCB_ICSR's address + movs r1, #1 @ prepare left shift (1 << 27) + lsls r1, #27 @ shift the bit + str r1, [r0] @ clear pending flag + cpsid i @ ensure we have priority 0 during re-scheduling + movs r1, #0 @ desched nothing + movs r0, #0 @ resched nothing + bl svc_handler @ re-schedule the highest priority task + cpsie i @ leave priority 0 + pop {r3, pc} @ return from exception diff --git a/core/cortex-m0/task.c b/core/cortex-m0/task.c index 654711ff6d..27465080a6 100644 --- a/core/cortex-m0/task.c +++ b/core/cortex-m0/task.c @@ -59,7 +59,6 @@ static uint32_t task_switches; /* Number of times active task changed */ static uint32_t irq_dist[CONFIG_IRQ_COUNT]; /* Distribution of IRQ calls */ #endif -extern void __switchto(task_ *from, task_ *to); extern int __task_start(int *task_stack_ready); #ifndef CONFIG_LOW_POWER_IDLE @@ -124,7 +123,7 @@ uint8_t task_stacks[0 /* Reserve space to discard context on first context switch. */ uint32_t scratchpad[17]; -static task_ *current_task = (task_ *)scratchpad; +task_ *current_task = (task_ *)scratchpad; /* * Bitmap of all tasks ready to be run. @@ -260,18 +259,6 @@ task_ __attribute__((noinline)) *__svc_handler(int desched, task_id_t resched) return current; } -void svc_handler(int desched, task_id_t resched) -{ - /* - * The layout of the this routine (and the __svc_handler companion one) - * ensures that we are getting the right tail call optimization from - * the compiler. - */ - task_ *prev = __svc_handler(desched, resched); - if (current_task != prev) - __switchto(prev, current_task); -} - void __schedule(int desched, int resched) { register int p0 asm("r0") = desched; @@ -280,18 +267,6 @@ void __schedule(int desched, int resched) asm("svc 0" : : "r"(p0), "r"(p1)); } -void pendsv_handler(void) -{ - /* Clear pending flag */ - CPU_SCB_ICSR = (1 << 27); - - /* ensure we have priority 0 during re-scheduling */ - __asm__ __volatile__("cpsid i"); - /* re-schedule the highest priority task */ - svc_handler(0, 0); - __asm__ __volatile__("cpsie i"); -} - #ifdef CONFIG_TASK_PROFILING void task_start_irq_handler(void *excep_return) { |