linux-kernel - [RFC PATCH 29/36] arm_mpam: Add helpers to allocate monitors

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Message-Id: <20250711183648.30766-30-james.morse@arm.com>
Date: Fri, 11 Jul 2025 18:36:41 +0000
From: James Morse <james.morse@....com>
To: linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Cc: Rob Herring <robh@...nel.org>,
	Ben Horgan <ben.horgan@....com>,
	Rohit Mathew <rohit.mathew@....com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Zeng Heng <zengheng4@...wei.com>,
	Lecopzer Chen <lecopzerc@...dia.com>,
	Carl Worth <carl@...amperecomputing.com>,
	shameerali.kolothum.thodi@...wei.com,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	lcherian@...vell.com,
	bobo.shaobowang@...wei.com,
	tan.shaopeng@...itsu.com,
	baolin.wang@...ux.alibaba.com,
	Jamie Iles <quic_jiles@...cinc.com>,
	Xin Hao <xhao@...ux.alibaba.com>,
	peternewman@...gle.com,
	dfustini@...libre.com,
	amitsinght@...vell.com,
	David Hildenbrand <david@...hat.com>,
	Rex Nie <rex.nie@...uarmicro.com>,
	Dave Martin <dave.martin@....com>,
	Koba Ko <kobak@...dia.com>,
	James Morse <james.morse@....com>
Subject: [RFC PATCH 29/36] arm_mpam: Add helpers to allocate monitors

MPAM's MSC support a number of monitors, each of which supports
bandwidth counters, or cache-storage-utilisation counters. To use
a counter, a monitor needs to be configured. Add helpers to allocate
and free CSU or MBWU monitors.

Signed-off-by: James Morse <james.morse@....com>
---
 drivers/platform/arm64/mpam/mpam_devices.c  |  2 ++
 drivers/platform/arm64/mpam/mpam_internal.h | 35 +++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/platform/arm64/mpam/mpam_devices.c b/drivers/platform/arm64/mpam/mpam_devices.c
index 2cf081e7c4b2..b11503d8ef1b 100644
--- a/drivers/platform/arm64/mpam/mpam_devices.c
+++ b/drivers/platform/arm64/mpam/mpam_devices.c
@@ -338,6 +338,8 @@ mpam_class_alloc(u8 level_idx, enum mpam_class_types type, gfp_t gfp)
 	class->level = level_idx;
 	class->type = type;
 	INIT_LIST_HEAD_RCU(&class->classes_list);
+	ida_init(&class->ida_csu_mon);
+	ida_init(&class->ida_mbwu_mon);
 
 	list_add_rcu(&class->classes_list, &mpam_classes);
 
diff --git a/drivers/platform/arm64/mpam/mpam_internal.h b/drivers/platform/arm64/mpam/mpam_internal.h
index 1586d6bd12f0..aca91f7dfbf6 100644
--- a/drivers/platform/arm64/mpam/mpam_internal.h
+++ b/drivers/platform/arm64/mpam/mpam_internal.h
@@ -230,6 +230,9 @@ struct mpam_class {
 	/* member of mpam_classes */
 	struct list_head	classes_list;
 
+	struct ida		ida_csu_mon;
+	struct ida		ida_mbwu_mon;
+
 	struct mpam_garbage	garbage;
 };
 
@@ -305,6 +308,38 @@ struct mpam_msc_ris {
 	struct mpam_garbage	garbage;
 };
 
+static inline int mpam_alloc_csu_mon(struct mpam_class *class)
+{
+	struct mpam_props *cprops = &class->props;
+
+	if (!mpam_has_feature(mpam_feat_msmon_csu, cprops))
+		return -EOPNOTSUPP;
+
+	return ida_alloc_range(&class->ida_csu_mon, 0, cprops->num_csu_mon - 1,
+			       GFP_KERNEL);
+}
+
+static inline void mpam_free_csu_mon(struct mpam_class *class, int csu_mon)
+{
+	ida_free(&class->ida_csu_mon, csu_mon);
+}
+
+static inline int mpam_alloc_mbwu_mon(struct mpam_class *class)
+{
+	struct mpam_props *cprops = &class->props;
+
+	if (!mpam_has_feature(mpam_feat_msmon_mbwu, cprops))
+		return -EOPNOTSUPP;
+
+	return ida_alloc_range(&class->ida_mbwu_mon, 0,
+			       cprops->num_mbwu_mon - 1, GFP_KERNEL);
+}
+
+static inline void mpam_free_mbwu_mon(struct mpam_class *class, int mbwu_mon)
+{
+	ida_free(&class->ida_mbwu_mon, mbwu_mon);
+}
+
 /* List of all classes - protected by srcu*/
 extern struct srcu_struct mpam_srcu;
 extern struct list_head mpam_classes;
-- 
2.39.5