linux-kernel - [PATCH 29/33] arm_mpam: Probe for long/lwd mbwu counters

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Message-ID: <20251107123450.664001-30-ben.horgan@arm.com>
Date: Fri,  7 Nov 2025 12:34:46 +0000
From: Ben Horgan <ben.horgan@....com>
To: james.morse@....com
Cc: amitsinght@...vell.com,
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	Ben Horgan <ben.horgan@....com>,
	Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Subject: [PATCH 29/33] arm_mpam: Probe for long/lwd mbwu counters

From: Rohit Mathew <rohit.mathew@....com>

mpam v0.1 and versions above v1.0 support optional long counter for
memory bandwidth monitoring. The MPAMF_MBWUMON_IDR register has fields
indicating support for long counters.

Probe these feature bits.

The mpam_feat_msmon_mbwu feature is used to indicate that bandwidth
monitors are supported, instead of muddling this with which size of
bandwidth monitors, add an explicit 31 bit counter feature.

Signed-off-by: Rohit Mathew <rohit.mathew@....com>
[ morse: Added 31bit counter feature to simplify later logic ]
Signed-off-by: James Morse <james.morse@....com>
Reviewed-by: Ben Horgan <ben.horgan@....com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>
Tested-by: Fenghua Yu <fenghuay@...dia.com>
Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Tested-by: Peter Newman <peternewman@...gle.com>
Signed-off-by: Ben Horgan <ben.horgan@....com>
---
Changes since v3:
Only set the exact counter length that is supported
---
 drivers/resctrl/mpam_devices.c  | 34 +++++++++++++++++++++------------
 drivers/resctrl/mpam_internal.h |  3 +++
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index eea082dfcddc..e93f2e919a85 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -783,25 +783,35 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
 				dev_err_once(dev, "Counters are not usable because not-ready timeout was not provided by firmware.");
 		}
 		if (FIELD_GET(MPAMF_MSMON_IDR_MSMON_MBWU, msmon_features)) {
-			bool hw_managed;
+			bool has_long, hw_managed;
 			u32 mbwumon_idr = mpam_read_partsel_reg(msc, MBWUMON_IDR);
 
 			props->num_mbwu_mon = FIELD_GET(MPAMF_MBWUMON_IDR_NUM_MON, mbwumon_idr);
-			if (props->num_mbwu_mon)
+			if (props->num_mbwu_mon) {
 				mpam_set_feature(mpam_feat_msmon_mbwu, props);
 
-			if (FIELD_GET(MPAMF_MBWUMON_IDR_HAS_RWBW, mbwumon_idr))
-				mpam_set_feature(mpam_feat_msmon_mbwu_rwbw, props);
+				if (FIELD_GET(MPAMF_MBWUMON_IDR_HAS_RWBW, mbwumon_idr))
+					mpam_set_feature(mpam_feat_msmon_mbwu_rwbw, props);
 
-			/* Is NRDY hardware managed? */
-			hw_managed = mpam_ris_hw_probe_hw_nrdy(ris, MBWU);
-			if (hw_managed)
-				mpam_set_feature(mpam_feat_msmon_mbwu_hw_nrdy, props);
+				has_long = FIELD_GET(MPAMF_MBWUMON_IDR_HAS_LONG, mbwumon_idr);
+				if (has_long) {
+					if (FIELD_GET(MPAMF_MBWUMON_IDR_LWD, mbwumon_idr))
+						mpam_set_feature(mpam_feat_msmon_mbwu_63counter, props);
+					else
+						mpam_set_feature(mpam_feat_msmon_mbwu_44counter, props);
+				} else
+					mpam_set_feature(mpam_feat_msmon_mbwu_31counter, props);
 
-			/*
-			 * Don't warn about any missing firmware property for
-			 * MBWU NRDY - it doesn't make any sense!
-			 */
+				/* Is NRDY hardware managed? */
+				hw_managed = mpam_ris_hw_probe_hw_nrdy(ris, MBWU);
+				if (hw_managed)
+					mpam_set_feature(mpam_feat_msmon_mbwu_hw_nrdy, props);
+
+				/*
+				 * Don't warn about any missing firmware property for
+				 * MBWU NRDY - it doesn't make any sense!
+				 */
+			}
 		}
 	}
 
diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index 7c99d4f3dc9c..f3bf26b7fdaf 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -162,6 +162,9 @@ enum mpam_device_features {
 	mpam_feat_msmon_csu_xcl,
 	mpam_feat_msmon_csu_hw_nrdy,
 	mpam_feat_msmon_mbwu,
+	mpam_feat_msmon_mbwu_31counter,
+	mpam_feat_msmon_mbwu_44counter,
+	mpam_feat_msmon_mbwu_63counter,
 	mpam_feat_msmon_mbwu_capture,
 	mpam_feat_msmon_mbwu_rwbw,
 	mpam_feat_msmon_mbwu_hw_nrdy,
-- 
2.43.0