diff --git a/include/lib/extensions/amu.h b/include/lib/extensions/amu.h
index 3071464..84ed67f 100644
--- a/include/lib/extensions/amu.h
+++ b/include/lib/extensions/amu.h
@@ -1,35 +1,80 @@
 /*
- * Copyright (c) 2017, Arm Limited. All rights reserved.
+ * Copyright (c) 2017-2020, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-#ifndef __AMU_H__
-#define __AMU_H__
+#ifndef AMU_H
+#define AMU_H
 
-#include <platform_def.h>
 #include <stdint.h>
 
-#define AMU_GROUP0_NR_COUNTERS		4
-#define AMU_GROUP0_COUNTERS_MASK	0xf
+#include <cassert.h>
+#include <platform_def.h>
+
+#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
 #else
-#define AMU_GROUP1_COUNTERS_MASK	0
+#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		0
+#define	AMU_GROUP1_NR_COUNTERS		0U
 #endif
 
-#define AMU_GROUP0_MAX_NR_COUNTERS	4
-#define AMU_GROUP1_MAX_NR_COUNTERS	16
+CASSERT(AMU_GROUP1_COUNTERS_MASK <= 0xffff, invalid_amu_group1_counters_mask);
 
 int amu_supported(void);
-uint64_t amu_group0_cnt_read(int idx);
-uint64_t amu_group1_cnt_read(int idx);
+int amu_supported_8_6(void);
 
-#endif /* __AMU_H__ */
+uint64_t amu_group0_cnt_read(unsigned int idx);
+#if __aarch64__
+uint64_t amu_group0_voffset_read(unsigned int idx);
+void amu_group0_voffset_write(unsigned int idx, uint64_t val);
+#endif
+
+#if AMU_GROUP1_NR_COUNTERS
+uint64_t amu_group1_cnt_read(unsigned int idx);
+#if __aarch64__
+uint64_t amu_group1_voffset_read(unsigned int idx);
+void amu_group1_voffset_write(unsigned int idx, uint64_t val);
+#endif
+#endif
+
+#endif /* AMU_H */