SPM: Implement global response buffer helpers

This buffer is where all the responses from Secure Partitions are stored
until they are requested.

Change-Id: Iafeb8f0848c5ff6f3e187060cd3a47702484dc45
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

include/plat/arm/common/arm_spm_def.h

@@ -139,5 +139,6 @@
 #define PLAT_SPM_SERVICES_MAX		U(30)
 
 #define PLAT_SPCI_HANDLES_MAX_NUM	U(20)
+#define PLAT_SPM_RESPONSES_MAX		U(30)
 
 #endif /* ARM_SPM_DEF_H */

services/std_svc/spm/spm.mk

@@ -19,6 +19,7 @@ SPM_SOURCES	:=	$(addprefix services/std_svc/spm/,	\
 			sp_setup.c				\
 			sp_xlat.c				\
 			spci.c					\
+			spm_buffers.c				\
 			spm_main.c				\
 			sprt.c)					\
 			${SPRT_LIB_SOURCES}

services/std_svc/spm/spm_buffers.c

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2018, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <platform_def.h>
+#include <spinlock.h>
+#include <utils_def.h>
+
+/*******************************************************************************
+ * Secure Service response global array. All the responses to the requests done
+ * to the Secure Partition are stored here. They are removed from the array as
+ * soon as their value is read.
+ ******************************************************************************/
+struct sprt_response {
+	int is_valid;
+	uint32_t token;
+	uint16_t client_id, handle;
+	u_register_t x1, x2, x3;
+};
+
+static struct sprt_response responses[PLAT_SPM_RESPONSES_MAX];
+
+static spinlock_t responses_lock;
+
+/* Add response to the global response buffer. Returns 0 on success else -1. */
+int spm_response_add(uint16_t client_id, uint16_t handle, uint32_t token,
+		     u_register_t x1, u_register_t x2, u_register_t x3)
+{
+	spin_lock(&responses_lock);
+
+	/* Make sure that there isn't any other response with the same token. */
+	for (unsigned int i = 0U; i < ARRAY_SIZE(responses); i++) {
+		struct sprt_response *resp = &(responses[i]);
+
+		if ((resp->is_valid == 1) && (resp->token == token)) {
+			return -1;
+		}
+	}
+
+	for (int i = 0; i < ARRAY_SIZE(responses); i++) {
+		struct sprt_response *resp = &(responses[i]);
+
+		if (resp->is_valid == 0) {
+			resp->token = token;
+			resp->client_id = client_id;
+			resp->handle = handle;
+			resp->x1 = x1;
+			resp->x2 = x2;
+			resp->x3 = x3;
+
+			dmbish();
+
+			resp->is_valid = 1;
+
+			spin_unlock(&responses_lock);
+
+			return 0;
+		}
+	}
+
+	spin_unlock(&responses_lock);
+
+	return -1;
+}
+
+/*
+ * Returns a response from the requests array and removes it from it. Returns 0
+ * on success, -1 if it wasn't found.
+ */
+int spm_response_get(uint16_t client_id, uint16_t handle, uint32_t token,
+		     u_register_t *x1, u_register_t *x2, u_register_t *x3)
+{
+	spin_lock(&responses_lock);
+
+	for (unsigned int i = 0U; i < ARRAY_SIZE(responses); i++) {
+		struct sprt_response *resp = &(responses[i]);
+
+		/* Ignore invalid entries */
+		if (resp->is_valid == 0) {
+			continue;
+		}
+
+		/* Make sure that all the information matches the stored one */
+		if ((resp->token != token) || (resp->client_id != client_id) ||
+		    (resp->handle != handle)) {
+			continue;
+		}
+
+		*x1 = resp->x1;
+		*x2 = resp->x2;
+		*x3 = resp->x3;
+
+		dmbish();
+
+		resp->is_valid = 0;
+
+		spin_unlock(&responses_lock);
+
+		return 0;
+	}
+
+	spin_unlock(&responses_lock);
+
+	return -1;
+}

services/std_svc/spm/spm_private.h

@@ -104,6 +104,12 @@ void spm_cpu_set_sp_ctx(unsigned int linear_id, sp_context_t *sp_ctx);
 sp_context_t *spm_cpu_get_sp_ctx(unsigned int linear_id);
 sp_context_t *spm_sp_get_by_uuid(const uint32_t (*svc_uuid)[4]);
 
+/* Functions to manipulate response and requests buffers */
+int spm_response_add(uint16_t client_id, uint16_t handle, uint32_t token,
+		     u_register_t x1, u_register_t x2, u_register_t x3);
+int spm_response_get(uint16_t client_id, uint16_t handle, uint32_t token,
+		     u_register_t *x1, u_register_t *x2, u_register_t *x3);
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* SPM_PRIVATE_H */