Patchwork [1/4] Add helpers for finding a device node which as a certain property

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Submitter Michael Ellerman
Date Nov. 13, 2008, 4:20 a.m.
Message ID <2743c30c538d24a0befee055bd6e0fcd746d0e82.1226550015.git.michael@ellerman.id.au>
Download mbox | patch
Permalink /patch/8527/
State Superseded, archived
Headers show

Comments

Michael Ellerman - Nov. 13, 2008, 4:20 a.m.
This commit adds a routine for finding a device node which has a certain
property, the contents of the property are not taken into account,
merely the presence or absence of the property.

Based on that routine, we add a for_each_ macro for iterating over all
nodes that have a certain property.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
---
 drivers/of/base.c  |   34 ++++++++++++++++++++++++++++++++++
 include/linux/of.h |    6 ++++++
 2 files changed, 40 insertions(+), 0 deletions(-)
David Miller - Nov. 13, 2008, 6:46 a.m.
From: Michael Ellerman <michael@ellerman.id.au>
Date: Thu, 13 Nov 2008 15:20:35 +1100 (EST)

> +	np = from ? from->allnext : allnodes;
> +	for (; np; np = np->allnext) {
> +		for (pp = np->properties; pp != 0; pp = pp->next) {
> +			if (of_prop_cmp(pp->name, prop_name) == 0) {
> +				goto out;
> +			}
> +		}
> +	}

We're starting to duplicate a lot of code in this file.

Perhaps split out the locked section of of_find_proeprty() into
a __of_find_property() and use that here and in of_find_property()
as well?

staitc struct property *__of_find_property(const struct device_node *np,
					   const char *name,
					   int *lenp)
{
	struct property *pp;

	for (pp = np->properties; pp != 0; pp = pp->next) {
		if (of_prop_cmp(pp->name, name) == 0) {
			if (lenp != 0)
				*lenp = pp->length;
			break;
		}
	}

	return pp;
}

struct property *of_find_property(const struct device_node *np,
				  const char *name,
				  int *lenp)
{
	struct property *pp;

	if (!np)
		return NULL;

	read_lock(&devtree_lock);
	pp = __of_find_property(np, name, lenp);
	read_unlock(&devtree_lock);

	return pp;
}
EXPORT_SYMBOL(of_find_property);
Michael Ellerman - Nov. 13, 2008, 6:49 a.m.
On Wed, 2008-11-12 at 22:46 -0800, David Miller wrote:
> From: Michael Ellerman <michael@ellerman.id.au>
> Date: Thu, 13 Nov 2008 15:20:35 +1100 (EST)
> 
> > +	np = from ? from->allnext : allnodes;
> > +	for (; np; np = np->allnext) {
> > +		for (pp = np->properties; pp != 0; pp = pp->next) {
> > +			if (of_prop_cmp(pp->name, prop_name) == 0) {
> > +				goto out;
> > +			}
> > +		}
> > +	}
> 
> We're starting to duplicate a lot of code in this file.

Agreed.

> Perhaps split out the locked section of of_find_proeprty() into
> a __of_find_property() and use that here and in of_find_property()
> as well?

Yeah I thought about it, but decided it wasn't worth it. But I'll try it
and see how the sizes end up.

cheers
Michael Ellerman - Nov. 13, 2008, 7:11 a.m.
On Thu, 2008-11-13 at 17:49 +1100, Michael Ellerman wrote:
> On Wed, 2008-11-12 at 22:46 -0800, David Miller wrote:
> > From: Michael Ellerman <michael@ellerman.id.au>
> > Date: Thu, 13 Nov 2008 15:20:35 +1100 (EST)
> > 
> > > +	np = from ? from->allnext : allnodes;
> > > +	for (; np; np = np->allnext) {
> > > +		for (pp = np->properties; pp != 0; pp = pp->next) {
> > > +			if (of_prop_cmp(pp->name, prop_name) == 0) {
> > > +				goto out;
> > > +			}
> > > +		}
> > > +	}
> > 
> > We're starting to duplicate a lot of code in this file.
> 
> Agreed.
> 
> > Perhaps split out the locked section of of_find_proeprty() into
> > a __of_find_property() and use that here and in of_find_property()
> > as well?
> 
> Yeah I thought about it, but decided it wasn't worth it. But I'll try it
> and see how the sizes end up.

With my compiler (4.3.1) it just gets inlined and actually makes the
text 8 bytes larger. We might be using different CFLAGs to sparc though.

I didn't think it made the source significantly clearer to split out the
of_find_property() logic, especially seeing as we don't need the lenp
behaviour in of_find_node_with_property().

cheers
David Miller - Nov. 13, 2008, 7:31 a.m.
From: Michael Ellerman <michael@ellerman.id.au>
Date: Thu, 13 Nov 2008 18:11:43 +1100

> With my compiler (4.3.1) it just gets inlined and actually makes the
> text 8 bytes larger. We might be using different CFLAGs to sparc though.
> 
> I didn't think it made the source significantly clearer to split out the
> of_find_property() logic, especially seeing as we don't need the lenp
> behaviour in of_find_node_with_property().

Fair enough.

Patch

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 7c79e94..0c3dcd0 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -329,6 +329,40 @@  struct device_node *of_find_compatible_node(struct device_node *from,
 EXPORT_SYMBOL(of_find_compatible_node);
 
 /**
+ *	of_find_node_with_property - Find a node which has a property with
+ *                                   the given name.
+ *	@from:		The node to start searching from or NULL, the node
+ *			you pass will not be searched, only the next one
+ *			will; typically, you pass what the previous call
+ *			returned. of_node_put() will be called on it
+ *	@prop_name:	The name of the property to look for.
+ *
+ *	Returns a node pointer with refcount incremented, use
+ *	of_node_put() on it when done.
+ */
+struct device_node *of_find_node_with_property(struct device_node *from,
+	const char *prop_name)
+{
+	struct device_node *np;
+	struct property *pp;
+
+	read_lock(&devtree_lock);
+	np = from ? from->allnext : allnodes;
+	for (; np; np = np->allnext) {
+		for (pp = np->properties; pp != 0; pp = pp->next) {
+			if (of_prop_cmp(pp->name, prop_name) == 0) {
+				goto out;
+			}
+		}
+	}
+out:
+	of_node_put(from);
+	read_unlock(&devtree_lock);
+	return np;
+}
+EXPORT_SYMBOL(of_find_node_with_property);
+
+/**
  * of_match_node - Tell if an device_node has a matching of_match structure
  *	@matches:	array of of device match structures to search in
  *	@node:		the of device structure to match against
diff --git a/include/linux/of.h b/include/linux/of.h
index e2488f5..6a7efa2 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -57,6 +57,12 @@  extern struct device_node *of_get_next_child(const struct device_node *node,
 	for (child = of_get_next_child(parent, NULL); child != NULL; \
 	     child = of_get_next_child(parent, child))
 
+extern struct device_node *of_find_node_with_property(
+	struct device_node *from, const char *prop_name);
+#define for_each_node_with_property(dn, prop_name) \
+	for (dn = of_find_node_with_property(NULL, prop_name); dn; \
+	     dn = of_find_node_with_property(dn, prop_name))
+
 extern struct property *of_find_property(const struct device_node *np,
 					 const char *name,
 					 int *lenp);