zephyr: Update tasks shim to use K_THREAD_DEFINE

Use Zephyr's K_THREAD_DEFINE to statically create the needed threads
instead of dynamically creating them with k_thread_create().

This saves a small amount of RAM (40 bytes) and increases flash usage by
about 140 bytes.

This change should not merge until
https://github.com/zephyrproject-rtos/zephyr/pull/50508 merges.

BUG=none
BRANCH=none
TEST=zmake build -a
TEST=./twister
TEST=verify zephyr image boots on herobrine.  Verify thread priorities
are unchanged.

Cq-Depend: chromium:3936185
Signed-off-by: Keith Short <keithshort@chromium.org>
Change-Id: Ie11c8fd99e0d424e2a03f33c545fa847d9d73ff9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3916581
Reviewed-by: Fabio Baltieri <fabiobaltieri@google.com>
Code-Coverage: Zoss <zoss-cl-coverage@prod.google.com>

1 files changed, 23 insertions, 83 deletions

diff --git a/zephyr/shim/src/tasks.c b/zephyr/shim/src/tasks.c
index 4143215442..35d4ab7c42 100644
--- a/zephyr/shim/src/tasks.c
+++ b/zephyr/shim/src/tasks.c
@@ -18,14 +18,6 @@ BUILD_ASSERT(EC_TASK_PRIORITY(EC_TASK_PRIO_LOWEST) < K_IDLE_PRIO,
 	     "CONFIG_NUM_PREEMPT_PRIORITIES too small, some tasks would run at "
 	     "idle priority");
 
-/* Declare all task stacks here */
-#define CROS_EC_TASK(name, e, p, size, pr) \
-	K_THREAD_STACK_DEFINE(name##_STACK, size);
-#define TASK_TEST(name, e, p, size) CROS_EC_TASK(name, e, p, size)
-CROS_EC_TASK_LIST
-#undef CROS_EC_TASK
-#undef TASK_TEST
-
 /* Forward declare all task entry point functions */
 #define CROS_EC_TASK(name, entry, ...) void entry(void *p);
 #define TASK_TEST(name, entry, ...) CROS_EC_TASK(name, entry)
@@ -33,23 +25,14 @@ CROS_EC_TASK_LIST
 #undef CROS_EC_TASK
 #undef TASK_TEST
 
-/** Context for each CROS EC task that is run in its own zephyr thread */
-struct task_ctx_cfg {
-#ifdef CONFIG_THREAD_NAME
-	/** Name of thread (for debugging) */
-	const char *name;
-#endif
-	/** Address of Zephyr thread's stack */
-	k_thread_stack_t *stack;
-	/** Usabled size in bytes of above thread stack */
-	size_t stack_size;
-	/** Task (platform/ec) entry point */
-	void (*entry)(void *p);
-	/** The parameter that is passed into the task entry point */
-	intptr_t parameter;
-	/** The task priority */
-	int priority;
-};
+/* Statically declare all threads here */
+#define CROS_EC_TASK(name, entry, parameter, stack_size, priority)      \
+	K_THREAD_DEFINE(name, stack_size, entry, parameter, NULL, NULL, \
+			EC_TASK_PRIORITY(priority), 0, -1);
+#define TASK_TEST(name, e, p, size) CROS_EC_TASK(name, e, p, size)
+CROS_EC_TASK_LIST
+#undef CROS_EC_TASK
+#undef TASK_TEST
 
 struct task_ctx_base_data {
 	/** A wait-able event that is raised when a new task event is posted */
@@ -58,32 +41,20 @@ struct task_ctx_base_data {
 	atomic_t event_mask;
 };
 
-struct task_ctx_data {
-	/** Zephyr thread structure that hosts EC tasks */
-	struct k_thread zephyr_thread;
-	/** Zephyr thread id for above thread */
-	k_tid_t zephyr_tid;
-	/** Base context data */
-	struct task_ctx_base_data base;
-};
-
-#define CROS_EC_TASK(_name, _entry, _parameter, _size, _prio) \
-	{ .entry = _entry,                                    \
-	  .parameter = _parameter,                            \
-	  .stack = _name##_STACK,                             \
-	  .stack_size = _size,                                \
-	  .priority = EC_TASK_PRIORITY(_prio),                \
-	  COND_CODE_1(CONFIG_THREAD_NAME, (.name = #_name, ), ()) },
-#define TASK_TEST(_name, _entry, _parameter, _size) \
-	CROS_EC_TASK(_name, _entry, _parameter, _size)
-const static struct task_ctx_cfg shimmed_tasks_cfg[TASK_ID_COUNT] = {
-	CROS_EC_TASK_LIST
+/*
+ * Create a mapping from the cros-ec task ID to the Zephyr thread.
+ */
+#undef CROS_EC_TASK
+#define CROS_EC_TASK(_name, _entry, _parameter, _size, _prio) _name,
 #ifdef TEST_BUILD
-		[TASK_ID_TEST_RUNNER] = {},
+static k_tid_t task_to_k_tid[TASK_ID_COUNT] = {
+#else
+const static k_tid_t task_to_k_tid[TASK_ID_COUNT] = {
 #endif
+	CROS_EC_TASK_LIST
 };
 
-static struct task_ctx_data shimmed_tasks_data[TASK_ID_COUNT];
+static struct task_ctx_base_data shimmed_tasks_data[TASK_ID_COUNT];
 static struct task_ctx_base_data extra_tasks_data[EXTRA_TASK_COUNT];
 /* Task timer structures. Keep separate from the context ones to avoid memory
  * holes due to int64_t fields in struct _timeout.
@@ -104,7 +75,7 @@ static struct task_ctx_base_data *task_get_base_data(task_id_t cros_task_id)
 		return &extra_tasks_data[cros_task_id - TASK_ID_COUNT];
 	}
 
-	return &shimmed_tasks_data[cros_task_id].base;
+	return &shimmed_tasks_data[cros_task_id];
 }
 
 task_id_t task_get_current(void)
@@ -120,7 +91,7 @@ task_id_t task_get_current(void)
 #endif
 
 	for (size_t i = 0; i < TASK_ID_COUNT; ++i) {
-		if (shimmed_tasks_data[i].zephyr_tid == k_current_get())
+		if (task_to_k_tid[i] == k_current_get())
 			return i;
 	}
 
@@ -235,18 +206,6 @@ uint32_t task_wait_event_mask(uint32_t event_mask, int timeout_us)
 	return events & event_mask;
 }
 
-static void task_entry(void *task_context_cfg, void *task_context_data,
-		       void *unused1)
-{
-	ARG_UNUSED(task_context_data);
-	ARG_UNUSED(unused1);
-
-	struct task_ctx_cfg *const cfg = task_context_cfg;
-
-	/* Call into task entry point */
-	cfg->entry((void *)cfg->parameter);
-}
-
 /*
  * Callback function to use with k_timer_start to set the
  * TASK_EVENT_TIMER event on a task.
@@ -291,7 +250,7 @@ void timer_cancel(task_id_t cros_ec_task_id)
 #ifdef TEST_BUILD
 void set_test_runner_tid(void)
 {
-	shimmed_tasks_data[TASK_ID_TEST_RUNNER].zephyr_tid = k_current_get();
+	task_to_k_tid[TASK_ID_TEST_RUNNER] = k_current_get();
 }
 
 #ifdef CONFIG_TASKS_SET_TEST_RUNNER_TID_RULE
@@ -315,32 +274,13 @@ void start_ec_tasks(void)
 	}
 
 	for (size_t i = 0; i < TASK_ID_COUNT; ++i) {
-		struct task_ctx_data *const data = &shimmed_tasks_data[i];
-		const struct task_ctx_cfg *const cfg = &shimmed_tasks_cfg[i];
-
 #ifdef TEST_BUILD
-		/* Do not create thread for test runner; it will be set later */
+		/* The test runner thread is automatically started. */
 		if (i == TASK_ID_TEST_RUNNER) {
-			data->zephyr_tid = NULL;
 			continue;
 		}
 #endif
-
-		/*
-		 * TODO(b/172361873): Add K_FP_REGS for FPU tasks. See
-		 * comment in config.h for CONFIG_TASK_LIST for existing flags
-		 * implementation.
-		 */
-		data->zephyr_tid = k_thread_create(&data->zephyr_thread,
-						   cfg->stack, cfg->stack_size,
-						   task_entry, (void *)cfg,
-						   data, NULL, cfg->priority, 0,
-						   K_NO_WAIT);
-
-#ifdef CONFIG_THREAD_NAME
-		/* Name thread for debugging */
-		k_thread_name_set(data->zephyr_tid, cfg->name);
-#endif
+		k_thread_start(task_to_k_tid[i]);
 	}
 
 	tasks_started = 1;