[PATCH v2 2/4] coresight: syscfg: Match feature capabilities separately from device class

[Amir Ayupov]

A feature loads on a device when the two share any match flag. That works
for device classes, where a feature wants any one of them, but not for
capabilities a device may or may not have: a feature that sets a class
and a capability would still load on a device of that class without the
capability.

Reserve CS_CFG_MATCH_CAP_MASK for capability flags. A feature now loads on
a device that shares one of its other flags and has all of its
capabilities. Check this once in cscfg_load_feat_csdev(), which both the
feature and the device registration paths call. No capability flags are
defined yet, so matching is unchanged.

Assisted-by: Devmate:Opus-5.5
Signed-off-by: Amir Ayupov <aaupov at fb.com>
---
 .../hwtracing/coresight/coresight-config.h    |  6 ++++
 .../hwtracing/coresight/coresight-syscfg.c    | 35 +++++++++++++------
 2 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
index 90fd937d3bd83..af6ef96b9ae01 100644
--- a/drivers/hwtracing/coresight/coresight-config.h
+++ b/drivers/hwtracing/coresight/coresight-config.h
@@ -30,6 +30,12 @@
 #define CS_CFG_MATCH_CLASS_SRC_ALL	0x0001	/* match any source */
 #define CS_CFG_MATCH_CLASS_SRC_ETM4	0x0002	/* match any ETMv4 device */
 
+/*
+ * flags defining device capabilities a feature can require. A feature loads on
+ * a device that matches one of its classes and has all of its capabilities.
+ */
+#define CS_CFG_MATCH_CAP_MASK		0x0000ff00
+
 /* flags defining device instance matching - used in config match desc data. */
 #define CS_CFG_MATCH_INST_ANY		0x80000000 /* any instance of a class */
 
diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index a816c22c87bc8..1545d64afec01 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
@@ -172,7 +172,21 @@ cscfg_alloc_csdev_feat(struct coresight_device *csdev, struct cscfg_feature_desc
 }
 
 /* load one feature into one coresight device */
+/*
+ * A feature matches a device that shares one of its class flags and has all of
+ * the capability flags it requires.
+ */
+static bool cscfg_match_feat_csdev(u32 feat_flags, u32 csdev_flags)
+{
+	u32 caps = feat_flags & CS_CFG_MATCH_CAP_MASK;
+
+	return (feat_flags & csdev_flags & ~CS_CFG_MATCH_CAP_MASK) &&
+	       (csdev_flags & caps) == caps;
+}
+
+/* Load the feature into the device if it matches, otherwise skip it. */
 static int cscfg_load_feat_csdev(struct coresight_device *csdev,
+				 u32 match_flags,
 				 struct cscfg_feature_desc *feat_desc,
 				 struct cscfg_csdev_feat_ops *ops)
 {
@@ -183,6 +197,9 @@ static int cscfg_load_feat_csdev(struct coresight_device *csdev,
 	if (!ops->load_feat)
 		return -EINVAL;
 
+	if (!cscfg_match_feat_csdev(feat_desc->match_flags, match_flags))
+		return 0;
+
 	feat_csdev = cscfg_alloc_csdev_feat(csdev, feat_desc);
 	if (!feat_csdev)
 		return -ENOMEM;
@@ -212,11 +229,11 @@ static int cscfg_add_feat_to_csdevs(struct cscfg_feature_desc *feat_desc)
 	int err;
 
 	list_for_each_entry(csdev_item, &cscfg_mgr->csdev_desc_list, item) {
-		if (csdev_item->match_flags & feat_desc->match_flags) {
-			err = cscfg_load_feat_csdev(csdev_item->csdev, feat_desc, &csdev_item->ops);
-			if (err)
-				return err;
-		}
+		err = cscfg_load_feat_csdev(csdev_item->csdev,
+					    csdev_item->match_flags, feat_desc,
+					    &csdev_item->ops);
+		if (err)
+			return err;
 	}
 	return 0;
 }
@@ -739,11 +756,9 @@ static int cscfg_add_feats_csdev(struct coresight_device *csdev,
 		return -EINVAL;
 
 	list_for_each_entry(feat_desc, &cscfg_mgr->feat_desc_list, item) {
-		if (feat_desc->match_flags & match_flags) {
-			err = cscfg_load_feat_csdev(csdev, feat_desc, ops);
-			if (err)
-				break;
-		}
+		err = cscfg_load_feat_csdev(csdev, match_flags, feat_desc, ops);
+		if (err)
+			break;
 	}
 	return err;
 }
-- 
2.52.0