From 55a1266ec87b39b5b77341760a40a9a93f590286 Mon Sep 17 00:00:00 2001
From: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
Date: Mon, 2 Oct 2017 12:10:54 +0100
Subject: [PATCH] SDEI: Add API for explicit dispatch

This allows for other EL3 components to schedule an SDEI event dispatch
to Normal world upon the next ERET. The API usage constrains are set out
in the SDEI dispatcher documentation.

Documentation to follow.

Change-Id: Id534bae0fd85afc94523490098c81f85c4e8f019
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
---
 include/services/sdei.h                |  3 +
 services/std_svc/sdei/sdei_intr_mgmt.c | 86 ++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)

diff --git a/include/services/sdei.h b/include/services/sdei.h
index 72eb6d7d..b07e93b1 100644
--- a/include/services/sdei.h
+++ b/include/services/sdei.h
@@ -175,4 +175,7 @@ uint64_t sdei_smc_handler(uint32_t smc_fid,
 
 void sdei_init(void);
 
+/* Public API to dispatch an event to Normal world */
+int sdei_dispatch_event(int ev_num, unsigned int preempted_sec_state);
+
 #endif /* __SDEI_H__ */
diff --git a/services/std_svc/sdei/sdei_intr_mgmt.c b/services/std_svc/sdei/sdei_intr_mgmt.c
index d7cf289c..4551a8b1 100644
--- a/services/std_svc/sdei/sdei_intr_mgmt.c
+++ b/services/std_svc/sdei/sdei_intr_mgmt.c
@@ -465,6 +465,85 @@ int sdei_intr_handler(uint32_t intr_raw, uint32_t flags, void *handle,
 	return 0;
 }
 
+/* Explicitly dispatch the given SDEI event */
+int sdei_dispatch_event(int ev_num, unsigned int preempted_sec_state)
+{
+	sdei_entry_t *se;
+	sdei_ev_map_t *map;
+	cpu_context_t *ctx;
+	sdei_dispatch_context_t *disp_ctx;
+	sdei_cpu_state_t *state;
+
+	/* Validate preempted security state */
+	if ((preempted_sec_state != SECURE) || (preempted_sec_state != NON_SECURE))
+		return -1;
+
+	/* Can't dispatch if events are masked on this PE */
+	state = sdei_get_this_pe_state();
+	if (state->pe_masked == PE_MASKED)
+		return -1;
+
+	/* Event 0 can't be dispatched */
+	if (ev_num == SDEI_EVENT_0)
+		return -1;
+
+	/* Locate mapping corresponding to this event */
+	map = find_event_map(ev_num);
+	if (!map)
+		return -1;
+
+	/*
+	 * Statically-bound or dynamic maps are dispatched only as a result of
+	 * interrupt, and not upon explicit request.
+	 */
+	if (is_map_dynamic(map) || is_map_bound(map))
+		return -1;
+
+	/* The event must be private */
+	if (is_event_shared(map))
+		return -1;
+
+	/* Examine state of dispatch stack */
+	disp_ctx = get_outstanding_dispatch();
+	if (disp_ctx) {
+		/*
+		 * There's an outstanding dispatch. If the outstanding dispatch
+		 * is critical, no more dispatches are possible.
+		 */
+		if (is_event_critical(disp_ctx->map))
+			return -1;
+
+		/*
+		 * If the outstanding dispatch is Normal, only critical events
+		 * can be dispatched.
+		 */
+		if (is_event_normal(map))
+			return -1;
+	}
+
+	se = get_event_entry(map);
+	if (!can_sdei_state_trans(se, DO_DISPATCH))
+		return -1;
+
+	/* Activate the priority corresponding to the event being dispatched */
+	ehf_activate_priority(sdei_event_priority(map));
+
+	/*
+	 * We assume the current context is SECURE, and that it's already been
+	 * saved.
+	 */
+	ctx = restore_and_resume_ns_context();
+
+	/*
+	 * The caller has effectively terminated execution. Record to resume the
+	 * preempted context later when the event completes or
+	 * complete-and-resumes.
+	 */
+	setup_ns_dispatch(map, se, ctx, preempted_sec_state, 0);
+
+	return 0;
+}
+
 int sdei_event_complete(int resume, uint64_t pc)
 {
 	sdei_dispatch_context_t *disp_ctx;
@@ -556,6 +635,13 @@ int sdei_event_complete(int resume, uint64_t pc)
 		 * interrupt.
 		 */
 		plat_ic_end_of_interrupt(disp_ctx->intr_raw);
+	} else {
+		/*
+		 * An unbound event must have been dispatched explicitly.
+		 * Deactivate the priority level that was activated at the time
+		 * of explicit dispatch.
+		 */
+		ehf_deactivate_priority(sdei_event_priority(map));
 	}
 
 	if (is_event_shared(map))
-- 
2.30.2