Add irq_has_handler() and use it to fix GPIO IRQ assert (raspberrypi#2277)

Author: kilograham

src/rp2_common/hardware_gpio/gpio.c

@@ -184,12 +184,9 @@ static void _gpio_set_irq_enabled(uint gpio, uint32_t events, bool enabled, io_b
 }
 
 void gpio_set_irq_enabled(uint gpio, uint32_t events, bool enabled) {
-    // either this call disables the interrupt
-    // or callback should already be set (raw or using gpio_set_irq_callback)
+    // either this call disables the interrupt or callback should already be set.
     // this protects against enabling the interrupt without callback set
-    assert(!enabled
-                || (raw_irq_mask[get_core_num()] & (1ull<<gpio))
-                || callbacks[get_core_num()]);
+    assert(!enabled || irq_has_handler(IO_IRQ_BANK0));
 
     // Separate mask/force/status per-core, so check which core called, and
     // set the relevant IRQ controls.

src/rp2_common/hardware_irq/include/hardware/irq.h

@@ -403,9 +403,23 @@ void irq_add_shared_handler(uint num, irq_handler_t handler, uint8_t order_prior
  */
 void irq_remove_handler(uint num, irq_handler_t handler);
 
-/*! \brief Determine if the current handler for the given number is shared
+/*! \brief Determine if there is an installed IRQ handler for the given interrupt number
  *  \ingroup hardware_irq
  *
+ * See \ref irq_set_exclusive_handler() for discussion on the scope of handlers
+ * when using both cores.
+ *
+ * \param num Interrupt number \ref interrupt_nums
+ * \return true if the specified IRQ has a handler
+ */
+bool irq_has_handler(uint num);
+
+/*! \brief Determine if the current IRQ andler for the given interrupt number is shared
+ *  \ingroup hardware_irq
+ *
+ * See \ref irq_set_exclusive_handler() for discussion on the scope of handlers
+ * when using both cores.
+ *
  * \param num Interrupt number \ref interrupt_nums
  * \return true if the specified IRQ has a shared handler
  */

src/rp2_common/hardware_irq/irq.c

@@ -197,10 +197,16 @@ static inline bool is_shared_irq_raw_handler(irq_handler_t raw_handler) {
     return (uintptr_t)raw_handler - (uintptr_t)irq_handler_chain_slots < sizeof(irq_handler_chain_slots);
 }
 
+bool irq_has_handler(uint irq_num) {
+    check_irq_param(irq_num);
+    irq_handler_t handler = irq_get_vtable_handler(irq_num);
+    return handler && handler != __unhandled_user_irq;
+}
+
 bool irq_has_shared_handler(uint irq_num) {
     check_irq_param(irq_num);
     irq_handler_t handler = irq_get_vtable_handler(irq_num);
-    return handler && is_shared_irq_raw_handler(handler);
+    return is_shared_irq_raw_handler(handler);
 }
 
 #else // PICO_DISABLE_SHARED_IRQ_HANDLERS