Add support of counting of interrupts (#2149)

* Add support of counting of interrupts

* Update the timestamp when interrupt happens during dispatch. Also
clear out interrupts when setting up a new callback

app/modules/gpio.c

@@ -53,17 +53,31 @@ static void gpio_intr_callback_task (task_param_t param, uint8 priority)
     // GPIO callbacks are run in L0 and include the level as a parameter
     lua_State *L = lua_getstate();
     NODE_DBG("Calling: %08x\n", gpio_cb_ref[pin]);
-    //
-    if (!INTERRUPT_TYPE_IS_LEVEL(pin_int_type[pin])) {
-      // Edge triggered -- re-enable the interrupt
-      platform_gpio_intr_init(pin, pin_int_type[pin]);
-    }
+
+    bool needs_callback = 1;
+
+    while (needs_callback)  {
+      // Note that the interrupt level only modifies 'seen' and
+      // the base level only modifies 'reported'. 
 
       // Do the actual callback
       lua_rawgeti(L, LUA_REGISTRYINDEX, gpio_cb_ref[pin]);
       lua_pushinteger(L, level);
       lua_pushinteger(L, then);
-    lua_call(L, 2, 0);
+      uint16_t seen = pin_counter[pin].seen;
+      lua_pushinteger(L, 0x7fff & (seen - pin_counter[pin].reported));
+      pin_counter[pin].reported = seen & 0x7fff; // This will cause the next interrupt to trigger a callback
+      uint16_t diff = (seen ^ pin_counter[pin].seen);
+      // Needs another callback if seen changed but not if the top bit is set
+      needs_callback = diff <= 0x7fff && diff > 0;
+      if (needs_callback) {
+        // Fake this for next time (this only happens if another interrupt happens since
+        // we loaded the 'seen' variable.
+        then = system_get_time() & 0x7fffffff;
+      }
+
+      lua_call(L, 3, 0);
+    } 
 
     if (INTERRUPT_TYPE_IS_LEVEL(pin_int_type[pin])) {
       // Level triggered -- re-enable the callback
@@ -108,6 +122,14 @@ static int lgpio_trig( lua_State* L )
   // unreference any overwritten callback
   if(old_pin_ref != LUA_NOREF) luaL_unref(L, LUA_REGISTRYINDEX, old_pin_ref);
 
+  uint16_t seen;
+
+  // Make sure that we clear out any queued interrupts
+  do {
+    seen = pin_counter[pin].seen;
+    pin_counter[pin].reported = seen & 0x7fff;
+  } while (seen != pin_counter[pin].seen);
+
   NODE_DBG("Pin data: %d %d %08x, %d %d %d, %08x\n",
           pin, type, pin_mux[pin], pin_num[pin], pin_func[pin], pin_int_type[pin], gpio_cb_ref[pin]);
   platform_gpio_intr_init(pin, type);

app/platform/pin_map.c

@@ -9,6 +9,7 @@ uint8_t  pin_func[GPIO_PIN_NUM];
 #ifdef GPIO_INTERRUPT_ENABLE
 uint8_t  pin_num_inv[GPIO_PIN_NUM_INV];
 uint8_t  pin_int_type[GPIO_PIN_NUM];
+GPIO_INT_COUNTER pin_counter[GPIO_PIN_NUM];
 #endif
 
 typedef struct {

app/platform/pin_map.h

@@ -15,6 +15,13 @@ extern uint8_t  pin_func[GPIO_PIN_NUM];
 #ifdef GPIO_INTERRUPT_ENABLE
 extern uint8_t  pin_num_inv[GPIO_PIN_NUM_INV];
 extern uint8_t  pin_int_type[GPIO_PIN_NUM];
+typedef struct {
+  // These values have 15 bits of count, and the top bit
+  // in 'seen' is set if we are missing a task post
+  volatile uint16_t seen;
+  volatile uint16_t reported;
+} GPIO_INT_COUNTER;
+extern GPIO_INT_COUNTER pin_counter[GPIO_PIN_NUM];
 #endif
 
 void get_pin_map(void);

app/platform/platform.c

@@ -14,6 +14,8 @@
 #include "driver/uart.h"
 #include "driver/sigma_delta.h"
 
+#define INTERRUPT_TYPE_IS_LEVEL(x)   ((x) >= GPIO_PIN_INTR_LOLEVEL)
+
 #ifdef GPIO_INTERRUPT_ENABLE
 static task_handle_t gpio_task_handle;
 
@@ -226,13 +228,25 @@ static void ICACHE_RAM_ATTR platform_gpio_intr_dispatcher (void *dummy){
     if (gpio_status&1) {
       int i = pin_num_inv[j];
       if (pin_int_type[i]) {
+        uint16_t diff = pin_counter[i].seen ^ pin_counter[i].reported;
+
+        pin_counter[i].seen = 0x7fff & (pin_counter[i].seen + 1);
+
+        if (INTERRUPT_TYPE_IS_LEVEL(pin_int_type[i])) {
           //disable interrupt
           gpio_pin_intr_state_set(GPIO_ID_PIN(j), GPIO_PIN_INTR_DISABLE);
+        }
         //clear interrupt status
         GPIO_REG_WRITE(GPIO_STATUS_W1TC_ADDRESS, BIT(j));
+
+        if (diff == 0 || diff & 0x8000) {
           uint32 level = 0x1 & GPIO_INPUT_GET(GPIO_ID_PIN(j));
-	task_post_high (gpio_task_handle, (now << 8) + (i<<1) + level);
-	// We re-enable the interrupt when we execute the callback
+	  if (!task_post_high (gpio_task_handle, (now << 8) + (i<<1) + level)) {
+            // If we fail to post, then try on the next interrupt
+            pin_counter[i].seen |= 0x8000;
+          }
+          // We re-enable the interrupt when we execute the callback (if level)
+        }
       }
     }
   }

docs/en/modules/gpio.md

@@ -125,10 +125,15 @@ This function is not available if GPIO_INTERRUPT_ENABLE was undefined at compile
 - `type` "up", "down", "both", "low", "high", which represent *rising edge*, *falling edge*, *both 
 edges*, *low level*, and *high level* trigger modes respectivey. If the type is "none" or omitted 
 then the callback function is removed and the interrupt is disabled.
-- `callback_function(level, when)` callback function when trigger occurs. The level of the specified pin 
+- `callback_function(level, when, eventcount)` callback function when trigger occurs. The level of the specified pin 
 at the interrupt passed as the first parameter to the callback. The timestamp of the event is passed
 as the second parameter. This is in microseconds and has the same base as for `tmr.now()`. This timestamp
 is grabbed at interrupt level and is more consistent than getting the time in the callback function.
+This timestamp is normally of the first interrupt detected, but, under overload conditions, might be a later one.
+The eventcount is the number of interrupts that were elided for this callback. This works best for edge triggered
+interrupts and enables counting of edges. However, beware
+of switch bounces -- you can get multiple pulses for a single switch closure. Counting
+works best when the edges are digitally generated.
 The previous callback function will be used if the function is omitted.
 
 #### Returns