[RFC PATCH 02/10] arm_mpam: Carry mbw_min and the hard limit in mpam_config

[Jinjie Ruan]

Add mbw_min and max_limit to mpam_config so the bandwidth minimum and
the MBW_MAX hard-limit bit can be programmed per PARTID through resctrl.

The hard limit is a config bit of MPAMCFG_MBW_MAX, not a discoverable
capability, so mpam_feat_max_limit is set alongside mpam_feat_mbw_max.
mpam_reprogram_ris_partid() writes the config's mbw_min when its feature
bit is set, and sets the hard-limit bit from its own feature bit so
MBHDL can be set without MBW_MAX being written.

Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
 drivers/resctrl/mpam_devices.c  | 25 +++++++++++++++++++++----
 drivers/resctrl/mpam_internal.h |  3 +++
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/mpam_devices.c
index 0fbf3464e744..806bf61b6dbe 100644
--- a/drivers/resctrl/mpam_devices.c
+++ b/drivers/resctrl/mpam_devices.c
@@ -848,8 +848,11 @@ static void mpam_ris_hw_probe(struct mpam_msc_ris *ris)
 		 */
 		props->bwa_wd = min(props->bwa_wd, 16);
 
-		if (props->bwa_wd && FIELD_GET(MPAMF_MBW_IDR_HAS_MAX, mbw_features))
+		if (props->bwa_wd && FIELD_GET(MPAMF_MBW_IDR_HAS_MAX, mbw_features)) {
 			mpam_set_feature(mpam_feat_mbw_max, props);
+			/* The hard-limit bit is a config bit, not a capability */
+			mpam_set_feature(mpam_feat_max_limit, props);
+		}
 
 		if (props->bwa_wd && FIELD_GET(MPAMF_MBW_IDR_HAS_MIN, mbw_features))
 			mpam_set_feature(mpam_feat_mbw_min, props);
@@ -1586,6 +1589,9 @@ static void mpam_reprogram_ris_partid(struct mpam_msc_ris *ris, u16 partid,
 	if (mpam_has_feature(mpam_feat_mbw_min, rprops)) {
 		u16 val = 0;
 
+		if (mpam_has_feature(mpam_feat_mbw_min, cfg))
+			val = cfg->mbw_min;
+
 		if (mpam_has_quirk(T241_FORCE_MBW_MIN_TO_ONE, msc)) {
 			u16 min = mpam_wa_t241_force_mbw_min_to_one(rprops);
 
@@ -1597,10 +1603,19 @@ static void mpam_reprogram_ris_partid(struct mpam_msc_ris *ris, u16 partid,
 	}
 
 	if (mpam_has_feature(mpam_feat_mbw_max, rprops)) {
+		u32 val = MPAMCFG_MBW_MAX_MAX;
+
 		if (mpam_has_feature(mpam_feat_mbw_max, cfg))
-			mpam_write_partsel_reg(msc, MBW_MAX, cfg->mbw_max);
-		else
-			mpam_write_partsel_reg(msc, MBW_MAX, MPAMCFG_MBW_MAX_MAX);
+			val = cfg->mbw_max;
+
+		/*
+		 * The hard-limit bit follows its own feature bit: MBHDL can
+		 * be configured without MBW_MAX ever being written.
+		 */
+		if (mpam_has_feature(mpam_feat_max_limit, cfg) && cfg->max_limit)
+			val |= MPAMCFG_MBW_MAX_HARDLIM;
+
+		mpam_write_partsel_reg(msc, MBW_MAX, val);
 	}
 
 	if (mpam_has_feature(mpam_feat_mbw_prop, rprops))
@@ -2922,6 +2937,8 @@ static bool mpam_update_config(struct mpam_config *cfg,
 	maybe_update_config(cfg, mpam_feat_cpor_part, newcfg, cpbm, has_changes);
 	maybe_update_config(cfg, mpam_feat_mbw_part, newcfg, mbw_pbm, has_changes);
 	maybe_update_config(cfg, mpam_feat_mbw_max, newcfg, mbw_max, has_changes);
+	maybe_update_config(cfg, mpam_feat_mbw_min, newcfg, mbw_min, has_changes);
+	maybe_update_config(cfg, mpam_feat_max_limit, newcfg, max_limit, has_changes);
 
 	return has_changes;
 }
diff --git a/drivers/resctrl/mpam_internal.h b/drivers/resctrl/mpam_internal.h
index def0e3a65c23..f5efebde3c2c 100644
--- a/drivers/resctrl/mpam_internal.h
+++ b/drivers/resctrl/mpam_internal.h
@@ -188,6 +188,7 @@ enum mpam_device_features {
 	mpam_feat_msmon_mbwu_capture,
 	mpam_feat_msmon_mbwu_rwbw,
 	mpam_feat_partid_nrw,
+	mpam_feat_max_limit,
 	MPAM_FEATURE_LAST
 };
 
@@ -318,6 +319,8 @@ struct mpam_config {
 	u32	cpbm;
 	u32	mbw_pbm;
 	u16	mbw_max;
+	u16	mbw_min;
+	bool	max_limit;
 
 	struct mpam_garbage	garbage;
 };
-- 
2.34.1