Merge pull request #8904 from ZetaR60/RIOT_atmega_race_fix_alt

cpu/atmega_common: return to non-interrupt context swaps

boards/common/arduino-atmega/include/board_common.h

@@ -59,32 +59,6 @@ extern "C" {
 #define LED0_TOGGLE         (PORTB ^=  LED0_MASK)
 /** @} */
 
-/**
- * @brief   Context swap defines
- *
- * Setup to use PC5 which is pin change interrupt 13 (PCINT13)
- * This emulates a software triggered interrupt
- */
-#ifdef CPU_ATMEGA328P
-#define AVR_CONTEXT_SWAP_INIT do { \
-            DDRD |= (1 << PD7); \
-            PCICR |= (1 << PCIE2); \
-            PCMSK2 |= (1 << PCINT23); \
-} while (0)
-#define AVR_CONTEXT_SWAP_INTERRUPT_VECT  PCINT2_vect
-#define AVR_CONTEXT_SWAP_TRIGGER   PORTD ^= (1 << PD7)
-#endif
-
-#ifdef CPU_ATMEGA2560
-#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)
-#endif
-
 /**
  * @name    xtimer configuration values
  * @{

boards/jiminy-mega256rfr2/include/board.h

@@ -75,21 +75,6 @@ extern "C" {
 #define LED2_TOGGLE         (LED_PORT ^=  LED2_MASK)
 /** @} */
 
-/**
- * @name Context swap defines
- * This emulates a software triggered interrupt
- * @{
- */
-#define AVR_CONTEXT_SWAP_INIT do { \
-        DDRE |= (1 << PE7); \
-        EICRB |= (1 << ISC70); \
-        EIMSK |= (1 << INT7); \
-        sei(); \
-} while (0)
-#define AVR_CONTEXT_SWAP_INTERRUPT_VECT  INT7_vect
-#define AVR_CONTEXT_SWAP_TRIGGER   PORTE ^= (1 << PE7)
-/** @} */
-
 /**
  * @name xtimer configuration values
  * @{

boards/mega-xplained/include/board.h

@@ -49,22 +49,6 @@ extern "C" {
  */
 #define UART_STDIO_DEV       (UART_DEV(1))
 
-/**
- * @name    Context swap defines
- *
- * Setup to use PD7 which is pin change interrupt 31 (PCINT31)
- * This emulates a software triggered interrupt
- * @{
- */
-#define AVR_CONTEXT_SWAP_INIT do { \
-            DDRD |= (1 << PD7); \
-            PCICR |= (1 << PCIE3); \
-            PCMSK3 |= (1 << PCINT31); \
-} while (0)
-#define AVR_CONTEXT_SWAP_INTERRUPT_VECT  PCINT3_vect
-#define AVR_CONTEXT_SWAP_TRIGGER   PORTD ^= (1 << PD7)
-/** @} */
-
 /**
  * @name    xtimer configuration values
  *

boards/waspmote-pro/include/board.h

@@ -145,21 +145,6 @@ extern "C" {
                                      MUX_USB_XBEE_ON
 /** @} */
 
-/**
- * @brief 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)
-/** @cond INTERNAL */
-#define AVR_CONTEXT_SWAP_INTERRUPT_VECT  PCINT0_vect
-#define AVR_CONTEXT_SWAP_TRIGGER   PORTB ^= (1 << PB5)
-/** @endcond */
-
 /**
  * @name    xtimer configuration values
  * @{

cpu/atmega_common/include/cpu.h

@@ -97,6 +97,13 @@ __attribute__((always_inline)) static inline void cpu_print_last_instruction(voi
  */
 void atmega_stdio_init(void);
 
+/**
+ * @brief   Exit ISR mode and yield with a return from interrupt. Use at the
+ * end of ISRs in place of thread_yield_higher. If thread_yield is needed, use
+ * thread_yield followed by thread_yield_isr instead of thread_yield alone.
+ */
+void thread_yield_isr(void);
+
 #ifdef __cplusplus
 }
 #endif

cpu/atmega_common/periph/gpio.c

@@ -313,10 +313,9 @@ ISR(INT6_vect, ISR_BLOCK)
 }
 #endif
 
-#if defined(INT7_vect) && !defined(BOARD_JIMINY_MEGA256RFR2)
+#if defined(INT7_vect)
-/**< INT7 is context swap pin for the Jiminy board */
 ISR(INT7_vect, ISR_BLOCK)
 {
     irq_handler(7); /**< predefined interrupt pin */
 }
-#endif  /* INT7_vect && END BOARD_JIMINY_MEGA256RFR2 */
+#endif

cpu/atmega_common/periph/timer.c

@@ -176,6 +176,7 @@ static inline void _isr(tim_t tim, int chan)
 
     if (sched_context_switch_request) {
         thread_yield();
+        thread_yield_isr();
     }
 
     __exit_isr();

cpu/atmega_common/periph/uart.c

@@ -170,6 +170,7 @@ static inline void isr_handler(int num)
 
     if (sched_context_switch_request) {
         thread_yield();
+        thread_yield_isr();
     }
 }
 

cpu/atmega_common/thread_arch.c

@@ -29,31 +29,6 @@
 #include "board.h"
 
 
-/**
- * @brief AVR_CONTEXT_SWAP_INIT initialize 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 __)
  */
@@ -228,7 +203,6 @@ void cpu_switch_context_exit(void) __attribute__((naked));
 void cpu_switch_context_exit(void)
 {
     sched_run();
-    AVR_CONTEXT_SWAP_INIT;
     __enter_thread_mode();
 }
 
@@ -247,18 +221,25 @@ void NORETURN __enter_thread_mode(void)
 }
 
 void thread_yield_higher(void) {
-    AVR_CONTEXT_SWAP_TRIGGER;
+    if (irq_is_in() == 0) {
-}
-
-
-/* Use this interrupt to perform all context switches */
-ISR(AVR_CONTEXT_SWAP_INTERRUPT_VECT, ISR_NAKED) {
         __context_save();
         sched_run();
         __context_restore();
-    __asm__ volatile("reti");
+        __asm__ volatile("ret");
+    } else {
+        sched_context_switch_request = 1;
+    }
 }
 
+void thread_yield_isr(void) {
+    __context_save();
+    sched_run();
+    __context_restore();
+
+    __exit_isr();
+
+    __asm__ volatile("reti");
+}
 
 __attribute__((always_inline)) static inline void __context_save(void)
 {