[PATCH v2] OF: base: match each node compatible against all given matches first

[Sebastian Hesselbarth]

Currently, of_match_node compares each given match against all node's
compatible strings with of_device_is_compatible.

To achieve multiple compatible strings per node with ordering from
specific to generic, this requires given matches to be ordered from
specific to generic. For most of the drivers this is not true and also
an alphabetical ordering is more sane there.

Therefore, this patch modifies of_match_node to match each of the node's
compatible strings against all given matches first, before checking the
next compatible string. This implies that node's compatibles are ordered
from specific to generic while given matches can be in any order.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
---
Changelog:
v1->v2:
- Allow checks against nodes with no compatible (Reported by Rob Herring)
- Add some comments

Cc: Grant Likely <grant.likely@xxxxxxxxxx>
Cc: Rob Herring <rob.herring@xxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
Cc: Meelis Roos <mroos@xxxxxxxx>
Cc: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Cc: Scott Wood <scottwood@xxxxxxxxxxxxx>
Cc: devicetree@xxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 drivers/of/base.c |   53 +++++++++++++++++++++++++++++++++++++----------------
 1 files changed, 37 insertions(+), 16 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index f807d0e..8d007d8 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -731,24 +731,42 @@ static
 const struct of_device_id *__of_match_node(const struct of_device_id *matches,
 					   const struct device_node *node)
 {
+	const char *cp;
+	int cplen, l;
+
 	if (!matches)
 		return NULL;
 
-	while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
-		int match = 1;
-		if (matches->name[0])
-			match &= node->name
-				&& !strcmp(matches->name, node->name);
-		if (matches->type[0])
-			match &= node->type
-				&& !strcmp(matches->type, node->type);
-		if (matches->compatible[0])
-			match &= __of_device_is_compatible(node,
-							   matches->compatible);
-		if (match)
-			return matches;
-		matches++;
-	}
+	cp = __of_get_property(node, "compatible", &cplen);
+	do {
+		const struct of_device_id *m = matches;
+
+		/* Check against matches with current compatible string */
+		while (m->name[0] || m->type[0] || m->compatible[0]) {
+			int match = 1;
+			if (m->name[0])
+				match &= node->name
+					&& !strcmp(m->name, node->name);
+			if (m->type[0])
+				match &= node->type
+					&& !strcmp(m->type, node->type);
+			if (m->compatible[0])
+				match &= cp
+					&& !of_compat_cmp(m->compatible, cp,
+							strlen(m->compatible));
+			if (match)
+				return m;
+			m++;
+		}
+
+		/* Get node's next compatible string */ 
+		if (cp) {
+			l = strlen(cp) + 1;
+			cp += l;
+			cplen -= l;
+		}
+	} while (cp && (cplen > 0));
+
 	return NULL;
 }
 
@@ -757,7 +775,10 @@ const struct of_device_id *__of_match_node(const struct of_device_id *matches,
  *	@matches:	array of of device match structures to search in
  *	@node:		the of device structure to match against
  *
- *	Low level utility function used by device matching.
+ *	Low level utility function used by device matching. Matching order
+ *	is to compare each of the node's compatibles with all given matches
+ *	first. This implies node's compatible is sorted from specific to
+ *	generic while matches can be in any order.
  */
 const struct of_device_id *of_match_node(const struct of_device_id *matches,
 					 const struct device_node *node)
-- 
1.7.2.5

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