Add interrupt support for emulator

This provides us a way to inject interrupts during a test. If a test has
interrupt_generator() defined, it will run in a separate thread. The
generator can then trigger interrupts when it decides to. The current
running task is suspended while emulator is executing ISR.

Also fixes a bug that tasks run without scheduler notifying them during
emulator start-up.

BUG=chrome-os-partner:19235
TEST=Repeatedly run all tests.
BRANCH=None

Change-Id: I0f921c47c0f848a9626da6272d9040e2b7c5ac86
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/55671

include/task_id.h

@@ -53,7 +53,10 @@ enum {
 	/* Number of tasks */
 	TASK_ID_COUNT,
 	/* Special task identifiers */
-	TASK_ID_INVALID = 0xff  /* unable to find the task */
+#ifdef EMU_BUILD
+	TASK_ID_INT_GEN = 0xfe, /* interrupt generator */
+#endif
+	TASK_ID_INVALID = 0xff, /* unable to find the task */
 };
 #undef TASK
 

include/test_util.h

@@ -109,6 +109,28 @@ int test_get_error_count(void);
 int test_send_host_command(int command, int version, const void *params,
 			   int params_size, void *resp, int resp_size);
 
+/* Optionally defined interrupt generator entry point */
+void interrupt_generator(void);
+
+/*
+ * Trigger an interrupt. This function must only be called by interrupt
+ * generator.
+ */
+void task_trigger_test_interrupt(void (*isr)(void));
+
+/*
+ * Special implementation of udelay() for interrupt generator. Calls
+ * to udelay() from interrupt generator are delegated to this function
+ * automatically.
+ */
+void interrupt_generator_udelay(unsigned us);
+
+#ifdef EMU_BUILD
+void wait_for_task_started(void);
+#else
+static inline void wait_for_task_started(void) { }
+#endif
+
 uint32_t prng(uint32_t seed);
 
 uint32_t prng_no_seed(void);