diff --git a/docs/porting-guide.rst b/docs/porting-guide.rst
index f020ec9..51d2e64 100644
--- a/docs/porting-guide.rst
+++ b/docs/porting-guide.rst
@@ -549,6 +549,22 @@
    doesn't print anything to the console. If ``PLAT_LOG_LEVEL_ASSERT`` isn't
    defined, it defaults to ``LOG_LEVEL``.
 
+If the platform port uses the Activity Monitor Unit, the following constants
+may be defined:
+
+-  **PLAT\_AMU\_GROUP1\_COUNTERS\_MASK**
+   This mask reflects the set of group counters that should be enabled.  The
+   maximum number of group 1 counters supported by AMUv1 is 16 so the mask
+   can be at most 0xffff. If the platform does not define this mask, no group 1
+   counters are enabled. If the platform defines this mask, the following
+   constant needs to also be defined.
+
+-  **PLAT\_AMU\_GROUP1\_NR\_COUNTERS**
+   This value is used to allocate an array to save and restore the counters
+   specified by ``PLAT_AMU_GROUP1_COUNTERS_MASK`` on CPU suspend.
+   This value should be equal to the highest bit position set in the
+   mask, plus 1.  The maximum number of group 1 counters in AMUv1 is 16.
+
 File : plat\_macros.S [mandatory]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/include/lib/extensions/amu.h b/include/lib/extensions/amu.h
index bbefe8f..2ecbea5 100644
--- a/include/lib/extensions/amu.h
+++ b/include/lib/extensions/amu.h
@@ -7,9 +7,28 @@
 #ifndef __AMU_H__
 #define __AMU_H__
 
-/* Enable all group 0 counters */
+#include <sys/cdefs.h> /* for CASSERT() */
+#include <cassert.h>
+#include <platform_def.h>
+
+/* All group 0 counters */
 #define AMU_GROUP0_COUNTERS_MASK	0xf
 
+#ifdef PLAT_AMU_GROUP1_COUNTERS_MASK
+#define AMU_GROUP1_COUNTERS_MASK	PLAT_AMU_GROUP1_COUNTERS_MASK
+#else
+#define AMU_GROUP1_COUNTERS_MASK	0
+#endif
+
+#ifdef PLAT_AMU_GROUP1_NR_COUNTERS
+#define AMU_GROUP1_NR_COUNTERS		PLAT_AMU_GROUP1_NR_COUNTERS
+#else
+#define AMU_GROUP1_NR_COUNTERS		0
+#endif
+
+CASSERT(AMU_GROUP1_COUNTERS_MASK <= 0xffff, invalid_amu_group1_counters_mask);
+CASSERT(AMU_GROUP1_NR_COUNTERS <= 16, invalid_amu_group1_nr_counters);
+
 void amu_enable(int el2_unused);
 
 #endif /* __AMU_H__ */
diff --git a/lib/extensions/amu/aarch64/amu.c b/lib/extensions/amu/aarch64/amu.c
index 007b349..c00aa5a 100644
--- a/lib/extensions/amu/aarch64/amu.c
+++ b/lib/extensions/amu/aarch64/amu.c
@@ -36,5 +36,7 @@
 
 		/* Enable group 0 counters */
 		write_amcntenset0_el0(AMU_GROUP0_COUNTERS_MASK);
+		/* Enable group 1 counters */
+		write_amcntenset1_el0(AMU_GROUP1_COUNTERS_MASK);
 	}
 }