feat(interrupts): support for registering custom handler

This patch provides support for registering and unregistering
handler that is invoked by SP at the tail end of the virtual interrupt
processing.

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: Ia12686361063bb680ff32b4f4bf90e0af2521c36

4 files changed, 67 insertions, 3 deletions

diff --git a/spm/cactus/cactus_interrupt.c b/spm/cactus/cactus_interrupt.c
index ef3d5cc..f0d916f 100644
--- a/spm/cactus/cactus_interrupt.c
+++ b/spm/cactus/cactus_interrupt.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021, Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2022, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -22,6 +22,8 @@ extern void notification_pending_interrupt_handler(void);
 
 extern ffa_id_t g_ffa_id;
 
+extern spinlock_t sp_handler_lock[NUM_VINT_ID];
+
 void cactus_interrupt_handler(void)
 {
 	uint32_t intid = spm_interrupt_get();
@@ -59,4 +61,11 @@ void cactus_interrupt_handler(void)
 			 intid);
 		panic();
 	}
+
+	/* Invoke the tail end handler registered by the SP. */
+	spin_lock(&sp_handler_lock[intid]);
+	if (sp_interrupt_tail_end_handler[intid]) {
+		sp_interrupt_tail_end_handler[intid]();
+	}
+	spin_unlock(&sp_handler_lock[intid]);
 }
diff --git a/spm/cactus/cactus_main.c b/spm/cactus/cactus_main.c
index 58186d1..dd15d97 100644
--- a/spm/cactus/cactus_main.c
+++ b/spm/cactus/cactus_main.c
@@ -206,6 +206,9 @@ void __dead2 cactus_main(bool primary_cold_boot)
 
 		/* Configure and enable Stage-1 MMU, enable D-Cache */
 		cactus_plat_configure_mmu(ffa_id);
+
+		/* Initialize locks for tail end interrupt handler */
+		sp_handler_spin_lock_init();
 	}
 
 	/*
diff --git a/spm/common/sp_helpers.c b/spm/common/sp_helpers.c
index 77031f8..448084f 100644
--- a/spm/common/sp_helpers.c
+++ b/spm/common/sp_helpers.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2021, Arm Limited. All rights reserved.
+ * Copyright (c) 2018-2022, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -13,6 +13,10 @@
 
 #include "sp_helpers.h"
 
+spinlock_t sp_handler_lock[NUM_VINT_ID];
+
+void (*sp_interrupt_tail_end_handler[NUM_VINT_ID])(void);
+
 uintptr_t bound_rand(uintptr_t min, uintptr_t max)
 {
 	/*
@@ -80,3 +84,35 @@ void sp_sleep(uint32_t ms)
 {
 	(void)sp_sleep_elapsed_time(ms);
 }
+
+void sp_handler_spin_lock_init(void)
+{
+	for (uint32_t i = 0; i < NUM_VINT_ID; i++) {
+		init_spinlock(&sp_handler_lock[i]);
+	}
+}
+
+void sp_register_interrupt_tail_end_handler(void (*handler)(void),
+			uint32_t interrupt_id)
+{
+	if (interrupt_id >= NUM_VINT_ID) {
+		ERROR("Cannot register handler for interrupt %u\n", interrupt_id);
+		panic();
+	}
+
+	spin_lock(&sp_handler_lock[interrupt_id]);
+	sp_interrupt_tail_end_handler[interrupt_id] = handler;
+	spin_unlock(&sp_handler_lock[interrupt_id]);
+}
+
+void sp_unregister_interrupt_tail_end_handler(uint32_t interrupt_id)
+{
+	if (interrupt_id >= NUM_VINT_ID) {
+		ERROR("Cannot unregister handler for interrupt %u\n", interrupt_id);
+		panic();
+	}
+
+	spin_lock(&sp_handler_lock[interrupt_id]);
+	sp_interrupt_tail_end_handler[interrupt_id] = NULL;
+	spin_unlock(&sp_handler_lock[interrupt_id]);
+}
diff --git a/spm/common/sp_helpers.h b/spm/common/sp_helpers.h
index 6fe8ec0..ef60221 100644
--- a/spm/common/sp_helpers.h
+++ b/spm/common/sp_helpers.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2021, Arm Limited. All rights reserved.
+ * Copyright (c) 2018-2022, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -10,6 +10,10 @@
 #include <stdint.h>
 #include <tftf_lib.h>
 #include <spm_common.h>
+#include <spinlock.h>
+
+/* Currently, Hafnium/SPM supports only 64 virtual interrupt IDs. */
+#define NUM_VINT_ID	64
 
 typedef struct {
 	u_register_t fid;
@@ -62,4 +66,16 @@ uint64_t sp_sleep_elapsed_time(uint32_t ms);
 /* Sleep for at least 'ms' milliseconds. */
 void sp_sleep(uint32_t ms);
 
+void sp_handler_spin_lock_init(void);
+
+/* Handler invoked at the tail end of interrupt processing by SP. */
+extern void (*sp_interrupt_tail_end_handler[NUM_VINT_ID])(void);
+
+/* Register the handler. */
+void sp_register_interrupt_tail_end_handler(void (*handler)(void),
+						uint32_t interrupt_id);
+
+/* Un-register the handler. */
+void sp_unregister_interrupt_tail_end_handler(uint32_t interrupt_id);
+
 #endif /* SP_HELPERS_H */