diff --git a/include/lib/extensions/amu.h b/include/lib/extensions/amu.h
index 99ecfcc..dcbdd5a 100644
--- a/include/lib/extensions/amu.h
+++ b/include/lib/extensions/amu.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -10,13 +10,14 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#include <platform_def.h>
-
 #include <lib/cassert.h>
 #include <lib/utils_def.h>
 
+#include <platform_def.h>
+
 /* All group 0 counters */
 #define AMU_GROUP0_COUNTERS_MASK	U(0xf)
+#define AMU_GROUP0_NR_COUNTERS		U(4)
 
 #ifdef PLAT_AMU_GROUP1_COUNTERS_MASK
 #define AMU_GROUP1_COUNTERS_MASK	PLAT_AMU_GROUP1_COUNTERS_MASK
@@ -24,25 +25,67 @@
 #define AMU_GROUP1_COUNTERS_MASK	U(0)
 #endif
 
-#ifdef PLAT_AMU_GROUP1_NR_COUNTERS
-#define AMU_GROUP1_NR_COUNTERS		PLAT_AMU_GROUP1_NR_COUNTERS
+/* Calculate number of group 1 counters */
+#if (AMU_GROUP1_COUNTERS_MASK	& (1 << 15))
+#define	AMU_GROUP1_NR_COUNTERS		16U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 14))
+#define	AMU_GROUP1_NR_COUNTERS		15U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 13))
+#define	AMU_GROUP1_NR_COUNTERS		14U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 12))
+#define	AMU_GROUP1_NR_COUNTERS		13U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 11))
+#define	AMU_GROUP1_NR_COUNTERS		12U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 10))
+#define	AMU_GROUP1_NR_COUNTERS		11U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 9))
+#define	AMU_GROUP1_NR_COUNTERS		10U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 8))
+#define	AMU_GROUP1_NR_COUNTERS		9U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 7))
+#define	AMU_GROUP1_NR_COUNTERS		8U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 6))
+#define	AMU_GROUP1_NR_COUNTERS		7U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 5))
+#define	AMU_GROUP1_NR_COUNTERS		6U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 4))
+#define	AMU_GROUP1_NR_COUNTERS		5U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 3))
+#define	AMU_GROUP1_NR_COUNTERS		4U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 2))
+#define	AMU_GROUP1_NR_COUNTERS		3U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 1))
+#define	AMU_GROUP1_NR_COUNTERS		2U
+#elif (AMU_GROUP1_COUNTERS_MASK	& (1 << 0))
+#define	AMU_GROUP1_NR_COUNTERS		1U
 #else
-#define AMU_GROUP1_NR_COUNTERS		U(0)
+#define	AMU_GROUP1_NR_COUNTERS		0U
 #endif
 
 CASSERT(AMU_GROUP1_COUNTERS_MASK <= 0xffff, invalid_amu_group1_counters_mask);
-CASSERT(AMU_GROUP1_NR_COUNTERS <= 16, invalid_amu_group1_nr_counters);
+
+struct amu_ctx {
+	uint64_t group0_cnts[AMU_GROUP0_NR_COUNTERS];
+
+#if AMU_GROUP1_NR_COUNTERS
+	uint64_t group1_cnts[AMU_GROUP1_NR_COUNTERS];
+#endif
+};
 
 bool amu_supported(void);
 void amu_enable(bool el2_unused);
 
 /* Group 0 configuration helpers */
-uint64_t amu_group0_cnt_read(int idx);
-void amu_group0_cnt_write(int idx, uint64_t val);
+uint64_t amu_group0_cnt_read(unsigned int idx);
+void amu_group0_cnt_write(unsigned int idx, uint64_t val);
+
+#if AMU_GROUP1_NR_COUNTERS
+bool amu_group1_supported(void);
 
 /* Group 1 configuration helpers */
-uint64_t amu_group1_cnt_read(int idx);
-void amu_group1_cnt_write(int idx, uint64_t val);
-void amu_group1_set_evtype(int idx, unsigned int val);
+uint64_t amu_group1_cnt_read(unsigned int idx);
+void amu_group1_cnt_write(unsigned int idx, uint64_t val);
+void amu_group1_set_evtype(unsigned int idx, unsigned int val);
+#endif
 
 #endif /* AMU_H */
diff --git a/include/lib/extensions/amu_private.h b/include/lib/extensions/amu_private.h
index ab4e6aa..30ce59d 100644
--- a/include/lib/extensions/amu_private.h
+++ b/include/lib/extensions/amu_private.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017-2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -9,11 +9,11 @@
 
 #include <stdint.h>
 
-uint64_t amu_group0_cnt_read_internal(int idx);
-void amu_group0_cnt_write_internal(int idx, uint64_t val);
+uint64_t amu_group0_cnt_read_internal(unsigned int idx);
+void amu_group0_cnt_write_internal(unsigned int idx, uint64_t val);
 
-uint64_t amu_group1_cnt_read_internal(int idx);
-void amu_group1_cnt_write_internal(int idx, uint64_t val);
-void amu_group1_set_evtype_internal(int idx, unsigned int val);
+uint64_t amu_group1_cnt_read_internal(unsigned int idx);
+void amu_group1_cnt_write_internal(unsigned int idx, uint64_t val);
+void amu_group1_set_evtype_internal(unsigned int idx, unsigned int val);
 
 #endif /* AMU_PRIVATE_H */