[RFC/PATCH] dt: Add of_device_compatible_match()

[Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>]

This provides an equivalent of of_fdt_match() for non-flat trees.

This is more practical than matching an array of of_device_id structs
when converting a bunch of existing users of of_fdt_match().

Signed-off-by: Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
---

This is a pre-requisite for some work I'm doing to move the platform
identification in arch/powerpc until after we have unflattened the
device-tree. Rewriting all those lists as of_device_id's would be
significantly cumbersome.

Note: untested other than it compiles. I want an agreement on the
interface ASAP since the conversion of all the platforms is a burden
I'd like to avoid doing twice.

diff --git a/drivers/of/base.c b/drivers/of/base.c
index ebf84e3..429c594 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -493,6 +493,28 @@ int of_device_is_compatible(const struct device_node *device,
 }
 EXPORT_SYMBOL(of_device_is_compatible);
 
+/** Checks if the device is compatible with any of the entries in
+ *  a NULL terminated array of strings. Returns the best match
+ *  score or 0.
+ */
+int of_device_compatible_match(struct device_node *device,
+			       const char *const *compat)
+{
+	unsigned int tmp, score = 0;
+
+	if (!compat)
+		return 0;
+
+	while (*compat) {
+		tmp = of_device_is_compatible(device, *compat);
+		if (tmp && (score == 0 || (tmp < score)))
+			score = tmp;
+		compat++;
+	}
+
+	return score;
+}
+
 /**
  * of_machine_is_compatible - Test root of device tree for a given compatible value
  * @compat: compatible string to look for in root node's compatible property.
diff --git a/include/linux/of.h b/include/linux/of.h
index 74eb28c..33c184d 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -324,6 +324,8 @@ extern int of_property_read_string_helper(const struct device_node *np,
 					      const char **out_strs, size_t sz, int index);
 extern int of_device_is_compatible(const struct device_node *device,
 				   const char *);
+extern int of_device_compatible_match(struct device_node *device,
+				      const char *const *compat);
 extern bool of_device_is_available(const struct device_node *device);
 extern bool of_device_is_big_endian(const struct device_node *device);
 extern const void *of_get_property(const struct device_node *node,
--
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