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atmega: use software interrupt for context swap #5763

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Merged
LudwigKnuepfer merged 1 commit into from
Sep 21, 2016
Merged

atmega: use software interrupt for context swap #5763

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16 changes: 16 additions & 0 deletions boards/arduino-mega2560/include/board.h
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,22 @@ extern "C" {
#define LED0_TOGGLE (PORTB ^= LED0_MASK)
/** @} */


/**
* Context swap defines
* Setup to use PJ6 which is pin change interrupt 15 (PCINT15)
* This emulates a software triggered interrupt
**/
#define AVR_CONTEXT_SWAP_INIT do { \
DDRJ |= (1 << PJ6); \
PCICR |= (1 << PCIE1); \
PCMSK1 |= (1 << PCINT15); \
} while (0)
#define AVR_CONTEXT_SWAP_INTERRUPT_VECT PCINT1_vect
#define AVR_CONTEXT_SWAP_TRIGGER PORTJ ^= (1 << PJ6)



/**
* @brief xtimer configuration values
* @{
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13 changes: 13 additions & 0 deletions boards/waspmote-pro/include/board.h
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Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,19 @@ extern "C" {

/** @} */

/**
* Context swap defines
* Setup to use PB5 which is pin change interrupt 5
* This emulates a software triggered interrupt
**/
#define AVR_CONTEXT_SWAP_INIT do { \
DDRB |= (1 << PB5); \
PCICR |= (1 << PCIE0); \
PCMSK0 |= (1 << PCINT5); \
} while (0)
#define AVR_CONTEXT_SWAP_INTERRUPT_VECT PCINT0_vect
#define AVR_CONTEXT_SWAP_TRIGGER PORTB ^= (1 << PB5)

/**
* @brief xtimer configuration values
* @{
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46 changes: 36 additions & 10 deletions cpu/atmega_common/thread_arch.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,11 +25,37 @@
#include "sched.h"
#include "irq.h"
#include "cpu.h"
#include "board.h"


/**
* @brief AVR_CONTEXT_SWAP_INIT intialize the context swap trigger
* Called when threading is first started.
*/
#ifndef AVR_CONTEXT_SWAP_INIT
#error AVR_CONTEXT_SWAP_INIT must be defined in board.h
#endif

/**
* @brief AVR_CONTEXT_SWAP_INTERRUPT_VECT Name of the ISR to use for context swapping
*/
#ifndef AVR_CONTEXT_SWAP_INTERRUPT_VECT
#error AVR_CONTEXT_SWAP_INTERRUPT_VECT must be defined in board.h
#endif

/**
* @brief AVR_CONTEXT_SWAP_TRIGGER executed to start the context swap
* When executed, this should result in the interrupt named in
* AVR_CONTEXT_SWAP_INTERRUPT_VECT being called
*/
#ifndef AVR_CONTEXT_SWAP_TRIGGER
#error ARV_CONTEXT_SWAP_TRIGGER must be defined in board.h
#endif


/*
* local function declarations (prefixed with __)
*/

static void __context_save(void);
static void __context_restore(void);
static void __enter_thread_mode(void);
Expand Down Expand Up @@ -122,7 +148,6 @@ char *thread_arch_stack_init(thread_task_func_t task_func, void *arg,
stk--;
*stk = (uint8_t) 0x00;
#endif

#if defined(RAMPZ)
stk--;
*stk = (uint8_t) 0x00;
Expand Down Expand Up @@ -221,6 +246,7 @@ void thread_arch_start_threading(void) __attribute__((naked));
void thread_arch_start_threading(void)
{
sched_run();
AVR_CONTEXT_SWAP_INIT;
__enter_thread_mode();
}

Expand All @@ -238,17 +264,17 @@ void NORETURN __enter_thread_mode(void)
UNREACHABLE();
}

void thread_arch_yield(void) __attribute__((naked));
void thread_arch_yield(void)
{
__context_save();
void thread_arch_yield(void) {
AVR_CONTEXT_SWAP_TRIGGER;
}

/* irq_disable(); */ /* gets already disabled during __context_save() */
sched_run();
irq_enable();

// Use this interrupt to perform all context switches
ISR(AVR_CONTEXT_SWAP_INTERRUPT_VECT, ISR_NAKED) {
__context_save();
sched_run();
__context_restore();
__asm__ volatile("ret");
__asm__ volatile("reti");
}


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