Merge pull request #6984 from stevew817/'efm32_irq_bugfix'

EFM32 IRQ handling fix

Author: Cruz Monrreal

targets/TARGET_Silicon_Labs/TARGET_EFM32/gpio_irq_api.c

@@ -61,12 +61,26 @@ static void handle_interrupt_in(uint8_t pin)
         return;
     }
 
-    // Get trigger event
+    // trying to discern which GPIO IRQ we got
     gpio_irq_event event = IRQ_NONE;
-    if (GPIO->EXTIFALL & (1 << pin)) {
+    if (((GPIO->EXTIFALL & (1 << pin)) != 0) && ((GPIO->EXTIRISE & (1 << pin)) == 0)) {
+        // Only the fall handler is active, so this must be a falling edge
         event = IRQ_FALL;
-    } else if (GPIO->EXTIRISE & (1 << pin)) {
+    } else if (((GPIO->EXTIFALL & (1 << pin)) == 0) && ((GPIO->EXTIRISE & (1 << pin)) != 0)) {
+        // Only the rise handler is active, so this must be a rising edge
         event = IRQ_RISE;
+    } else {
+        // Ambiguous as to which IRQ we've received. Poll the pin to check which one to fire.
+        // NOTE: If trying to detect a pulse where the width is shorter than this handler's
+        // reaction time, there will only be one callback (for the trailing edge) called.
+
+        // we are storing two ports in each uint8, so we must acquire the one we want.
+        // If pin is odd, the port is encoded in the 4 most significant bits.
+        // If pin is even, the port is encoded in the 4 least significant bits
+        uint8_t isRise = GPIO_PinInGet((pin & 0x1) ?
+                                       channel_ports[(pin>>1) & 0x7] >> 4 & 0xF :
+                                       channel_ports[(pin>>1) & 0x7] >> 0 & 0xF, pin);
+        event = (isRise == 1 ? IRQ_RISE : IRQ_FALL);
     }
     GPIO_IntClear(pin);
     irq_handler(channel_ids[pin], event);
@@ -132,9 +146,6 @@ void gpio_irq_set(gpio_irq_t *obj, gpio_irq_event event, uint32_t enable)
     /* Disable, set config and enable */
     gpio_irq_disable(obj);
 
-    bool was_disabled = false;
-    if(GPIO->IEN == 0) was_disabled = true;
-
     GPIO_IntConfig((GPIO_Port_TypeDef)((obj->pin >> 4) & 0xF), obj->pin &0xF, obj->risingEdge, obj->fallingEdge, obj->risingEdge || obj->fallingEdge);
 }