event: Add basic support for events
Add a way to create and dispatch events without needing to allocate
memory. Also add a way to 'spy' on events, thus allowing 'hooks' to be
created.
Use a linker list for static events, which we can use to replace functions
like arch_cpu_init_f(). Allow an EVENT_DEBUG option which makes it
easier to see what is going on at runtime, but uses more code space.
Dynamic events allow the creation of a spy at runtime. This is not always
necessary, but can be enabled with EVENT_DYNAMIC if needed.
A 'test' event is the only option for now.
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/common/event.c b/common/event.c
new file mode 100644
index 0000000..366be24
--- /dev/null
+++ b/common/event.c
@@ -0,0 +1,186 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Events provide a general-purpose way to react to / subscribe to changes
+ * within U-Boot
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#define LOG_CATEGORY LOGC_EVENT
+
+#include <common.h>
+#include <event.h>
+#include <event_internal.h>
+#include <log.h>
+#include <linker_lists.h>
+#include <malloc.h>
+#include <asm/global_data.h>
+#include <linux/list.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#if CONFIG_IS_ENABLED(EVENT_DEBUG)
+const char *const type_name[] = {
+ "none",
+ "test",
+};
+
+_Static_assert(ARRAY_SIZE(type_name) == EVT_COUNT, "event type_name size");
+#endif
+
+static const char *event_type_name(enum event_t type)
+{
+#if CONFIG_IS_ENABLED(EVENT_DEBUG)
+ return type_name[type];
+#else
+ return "(unknown)";
+#endif
+}
+
+static int notify_static(struct event *ev)
+{
+ struct evspy_info *start =
+ ll_entry_start(struct evspy_info, evspy_info);
+ const int n_ents = ll_entry_count(struct evspy_info, evspy_info);
+ struct evspy_info *spy;
+
+ for (spy = start; spy != start + n_ents; spy++) {
+ if (spy->type == ev->type) {
+ int ret;
+
+ log_debug("Sending event %x/%s to spy '%s'\n", ev->type,
+ event_type_name(ev->type), event_spy_id(spy));
+ ret = spy->func(NULL, ev);
+
+ /*
+ * TODO: Handle various return codes to
+ *
+ * - claim an event (no others will see it)
+ * - return an error from the event
+ */
+ if (ret)
+ return log_msg_ret("spy", ret);
+ }
+ }
+
+ return 0;
+}
+
+static int notify_dynamic(struct event *ev)
+{
+ struct event_state *state = gd_event_state();
+ struct event_spy *spy, *next;
+
+ list_for_each_entry_safe(spy, next, &state->spy_head, sibling_node) {
+ if (spy->type == ev->type) {
+ int ret;
+
+ log_debug("Sending event %x/%s to spy '%s'\n", ev->type,
+ event_type_name(ev->type), spy->id);
+ ret = spy->func(spy->ctx, ev);
+
+ /*
+ * TODO: Handle various return codes to
+ *
+ * - claim an event (no others will see it)
+ * - return an error from the event
+ */
+ if (ret)
+ return log_msg_ret("spy", ret);
+ }
+ }
+
+ return 0;
+}
+
+int event_notify(enum event_t type, void *data, int size)
+{
+ struct event event;
+ int ret;
+
+ event.type = type;
+ if (size > sizeof(event.data))
+ return log_msg_ret("size", -E2BIG);
+ memcpy(&event.data, data, size);
+
+ ret = notify_static(&event);
+ if (ret)
+ return log_msg_ret("dyn", ret);
+
+ if (CONFIG_IS_ENABLED(EVENT_DYNAMIC)) {
+ ret = notify_dynamic(&event);
+ if (ret)
+ return log_msg_ret("dyn", ret);
+ }
+
+ return 0;
+}
+
+int event_notify_null(enum event_t type)
+{
+ return event_notify(type, NULL, 0);
+}
+
+void event_show_spy_list(void)
+{
+ struct evspy_info *start =
+ ll_entry_start(struct evspy_info, evspy_info);
+ const int n_ents = ll_entry_count(struct evspy_info, evspy_info);
+ struct evspy_info *spy;
+ const int size = sizeof(ulong) * 2;
+
+ printf("Seq %-24s %*s %s\n", "Type", size, "Function", "ID");
+ for (spy = start; spy != start + n_ents; spy++) {
+ printf("%3x %-3x %-20s %*p %s\n", (uint)(spy - start),
+ spy->type, event_type_name(spy->type), size, spy->func,
+ event_spy_id(spy));
+ }
+}
+
+#if CONFIG_IS_ENABLED(EVENT_DYNAMIC)
+static void spy_free(struct event_spy *spy)
+{
+ list_del(&spy->sibling_node);
+}
+
+int event_register(const char *id, enum event_t type, event_handler_t func, void *ctx)
+{
+ struct event_state *state = gd_event_state();
+ struct event_spy *spy;
+
+ if (!CONFIG_IS_ENABLED(EVENT_DYNAMIC))
+ return -ENOSYS;
+ spy = malloc(sizeof(*spy));
+ if (!spy)
+ return log_msg_ret("alloc", -ENOMEM);
+
+ spy->id = id;
+ spy->type = type;
+ spy->func = func;
+ spy->ctx = ctx;
+ list_add_tail(&spy->sibling_node, &state->spy_head);
+
+ return 0;
+}
+
+int event_uninit(void)
+{
+ struct event_state *state = gd_event_state();
+ struct event_spy *spy, *next;
+
+ list_for_each_entry_safe(spy, next, &state->spy_head, sibling_node)
+ spy_free(spy);
+
+ return 0;
+}
+
+int event_init(void)
+{
+ struct event_state *state = gd_event_state();
+
+ INIT_LIST_HEAD(&state->spy_head);
+
+ return 0;
+}
+#endif /* EVENT_DYNAMIC */