Dispatch interrupts asynchroneously

This patch-set changes interrupt dispatching to happen asynchronously. This is a first step towards making API-calls interrupt safe. It also makes Epicardium more robust against a buggy payload as such a payload can no longer deadlock tasks which try to send interrupts (in such an instance, now they will be scheduled but never leave the IRQ queue).

Patch-List:

chore(interrupts): Make api_interrupt_trigger() return void

api_interrupt_trigger() cannot fail except by a programmer error (passing an invalid ID) in which case we should raise an assertion. Thus, make it return void instead of int.

fix(lifecycle): Don't trigger a reset during startup

This is a silent issue which I noticed during work in this patchset; we are sending a superfluous interrupt during boot. This patch changes this although it reduces readability of the code. I'd be ok with dropping it again if readability here is more important.

chore(interrupts): Move api into an epicardium module

Our buildsystem prevents implementing the task in epicardium/api so I moved the interrupts API into an Epicardium module.

chore(interrupts): Fix all modules to use new api

Update code-base to use new API.

feat(interrupts): Dispatch interrupts asynchroneously

Instead of blocking the triggering task when core 1 is still busy handling the previous interrupt, offload interrupt dispatching into a separate task. This is the first step towards making API-calls interrupt safe.

Next to the async triggering, the synchroneous mechanism is retained for special cases where async does not work (e.g. because of spin-locks). Currently, there is only one such case when resetting core 1 (triggering EPIC_INT_RESET).

docs(interrupts): Document new interrupt dispatcher task

Docs ...

Documentation/overview.rst

@@ -14,31 +14,34 @@ Epicardium
 Epicardium is based on `FreeRTOS <https://www.freertos.org/>`_.  There are a
 number of tasks that will have been keeping card10 running.  These are:
 
-+-------------------+-------------------------------+----------+-------------------------------------------+
-| Name              | ID Global                     | Priority | Description                               |
-+===================+===============================+==========+===========================================+
-| `vPmicTask`_      | ``pmic_task_id`` (static)     | +4       | Power Management (and Reset Button)       |
-+-------------------+-------------------------------+----------+-------------------------------------------+
-| `vLifecycleTask`_ | ``lifecycle_task`` (static)   | +3       | Control of the payload running on core 1. |
-+-------------------+-------------------------------+----------+-------------------------------------------+
-| `vBleTask`_       | ``ble_task_id`` (static)      | +3       | Bluetooth Low Energy Stack                |
-+-------------------+-------------------------------+----------+-------------------------------------------+
-| `vSerialTask`_    | ``serial_task_id``            | +3       | Serial Output via UART/CDC-ACM/BLE        |
-+-------------------+-------------------------------+----------+-------------------------------------------+
-| `vApiDispatcher`_ | ``dispatcher_task_id``        | +2       | Epicardium API dispatcher                 |
-+-------------------+-------------------------------+----------+-------------------------------------------+
-| `vLedTask`_       | -/-                           | +1       | LED Animations                            |
-+-------------------+-------------------------------+----------+-------------------------------------------+
-| `vMAX30001Task`_  | ``max30001_task_id`` (static) | +1       | `MAX30001`_ ECG driver                    |
-+-------------------+-------------------------------+----------+-------------------------------------------+
-| `vBhi160Task`_    | ``bhi160_task_id`` (static)   | +1       | `BHI160`_ sensor fusion driver            |
-+-------------------+-------------------------------+----------+-------------------------------------------+
++--------------------+-------------------------------+----------+-------------------------------------------+
+| Name               | ID Global                     | Priority | Description                               |
++====================+===============================+==========+===========================================+
+| `vPmicTask`_       | ``pmic_task_id`` (static)     | +4       | Power Management (and Reset Button)       |
++--------------------+-------------------------------+----------+-------------------------------------------+
+| `vLifecycleTask`_  | ``lifecycle_task`` (static)   | +3       | Control of the payload running on core 1. |
++--------------------+-------------------------------+----------+-------------------------------------------+
+| `vBleTask`_        | ``ble_task_id`` (static)      | +3       | Bluetooth Low Energy Stack                |
++--------------------+-------------------------------+----------+-------------------------------------------+
+| `vSerialTask`_     | ``serial_task_id``            | +3       | Serial Output via UART/CDC-ACM/BLE        |
++--------------------+-------------------------------+----------+-------------------------------------------+
+| `vApiDispatcher`_  | ``dispatcher_task_id``        | +2       | Epicardium API dispatcher                 |
++--------------------+-------------------------------+----------+-------------------------------------------+
+| `vInterruptsTask`_ | ``interrupts_task`` (static)  | +2       | Interrupt dispatcher worker               |
++--------------------+-------------------------------+----------+-------------------------------------------+
+| `vLedTask`_        | -/-                           | +1       | LED Animations                            |
++--------------------+-------------------------------+----------+-------------------------------------------+
+| `vMAX30001Task`_   | ``max30001_task_id`` (static) | +1       | `MAX30001`_ ECG driver                    |
++--------------------+-------------------------------+----------+-------------------------------------------+
+| `vBhi160Task`_     | ``bhi160_task_id`` (static)   | +1       | `BHI160`_ sensor fusion driver            |
++--------------------+-------------------------------+----------+-------------------------------------------+
 
 .. _vPmicTask: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/modules/pmic.c#L281
 .. _vLifecycleTask: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/modules/lifecycle.c#L361
 .. _vBleTask: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/ble/ble.c#L237
 .. _vSerialTask: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/modules/serial.c#L289
 .. _vApiDispatcher: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/modules/dispatcher.c#L25
+.. _vInterruptsTask: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/modules/interrupts.c#L119
 .. _vLedTask: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/modules/personal_state.c#L58
 .. _vMAX30001Task: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/modules/max30001.c#L378
 .. _vBhi160Task: https://git.card10.badge.events.ccc.de/card10/firmware/blob/master/epicardium/modules/bhi.c#L419