Commit fdc29a14 authored Nov 19, 2025 by Rohit Mathew Committed by Catalin Marinas Nov 19, 2025

arm_mpam: Probe for long/lwd mbwu counters



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@arm.com>
[ morse: Added 31bit counter feature to simplify later logic ]
Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Fenghua Yu <fenghuay@nvidia.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Carl Worth <carl@os.amperecomputing.com>
Tested-by: Gavin Shan <gshan@redhat.com>
Tested-by: Zeng Heng <zengheng4@huawei.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

parent b3536379

drivers/resctrl/mpam_devices.c

+23 −12

Original line number	Diff line number	Diff line
		@@ -783,16 +783,26 @@ 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);

		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);
		}

		/* Is NRDY hardware managed? */
		hw_managed = mpam_ris_hw_probe_hw_nrdy(ris, MBWU);
		if (hw_managed)
		@@ -804,6 +814,7 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
		*/
		}
		}
		}

		/*
		* RIS with PARTID narrowing don't have enough storage for one

drivers/resctrl/mpam_internal.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -164,6 +164,9 @@ 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,