Hi Grant,

Grant Likely [off-list ref] wrote @ Wed, 11 Dec 2013 14:28:45 +0100:

quoted

On Thu, 21 Nov 2013 11:57:00 -0700, Stephen Warren [off-list ref] wrote:

quoted

On 11/21/2013 10:17 AM, Hiroshi Doyu wrote:

quoted

Iterating over a property containing a list of phandles with arguments
is a common operation for device drivers. This patch adds a new
of_property_for_each_phandle_with_args() macro to make the iteration
simpler.

Signed-off-by: Hiroshi Doyu <redacted>
---
v6+:
Use the description, which Grant Likely proposed, to be full enough
that a future reader can figure out why a patch was written.
  http://lists.linuxfoundation.org/pipermail/iommu/2013-November/007062.html

...

quoted

That's right, I forgot I said that. Yes please fix the implementation.

Here's the latest. I'll include this with the next v7 series.

Can I get your Acked-by with this?

--8<----

From 8f7c0404aa68f0e8dbe0babc240590f6528ecc1f Mon Sep 17 00:00:00 2001
From: Hiroshi Doyu <redacted>
Date: Fri, 15 Nov 2013 10:52:53 +0200
Subject: [PATCH] of: introduce of_property_for_each_phandle_with_args()

Iterating over a property containing a list of phandles with arguments
is a common operation for device drivers. This patch adds a new
of_property_for_each_phandle_with_args() macro to make the iteration
simpler.

Signed-off-by: Hiroshi Doyu <redacted>
Cc: Rob Herring <redacted>
---
v7:
Fixed some minors pointed by Rob and Stephen.

v6++++:
Iterate without intrducing a new struct.

v6+++:
Introduced a new struct "of_phandle_iter" to keep the state when
iterating over the list.

v6++:
Optimized to avoid O(n^2), suggested by Stephen Warren.
http://lists.linuxfoundation.org/pipermail/iommu/2013-November/007066.html

I didn't introduce any struct to hold params and state here.

v6+:
Use the description, which Grant Likely proposed, to be full enough
that a future reader can figure out why a patch was written.

v5:
New patch for v5.

Signed-off-by: Hiroshi Doyu <redacted>
---
 drivers/of/base.c  | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of.h | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index f807d0e..cd4ab05 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c

@@ -1201,6 +1201,52 @@ void of_print_phandle_args(const char *msg, const struct of_phandle_args *args)
 	printk("\n");
 }
 
+const __be32 *of_phandle_iter_next(const char *cells_name, int cell_count,
+				   const __be32 *cur, const __be32 *end,
+				   struct of_phandle_args *out_args)

+{
+	struct device_node *dn;
+	int i;
+
+	if (!cells_name && !cell_count)
+		return NULL;
+
+	if (!cur || (cur >= end))
+		return NULL;
+
+	dn = of_find_node_by_phandle(be32_to_cpup(cur++));
+	if (!dn)
+		return NULL;
+
+	if (cells_name)
+		if (of_property_read_u32(dn, cells_name, &cell_count))
+			return NULL;
+
+	out_args->np = dn;
+	out_args->args_count = cell_count;
+	for (i = 0; i < cell_count; i++)
+		out_args->args[i] = be32_to_cpup(cur++);
+
+	return cur;
+}
+EXPORT_SYMBOL_GPL(of_phandle_iter_next);
+
+const __be32 *of_phandle_iter_init(const struct device_node *np,
+				   const char *list_name,
+				   const __be32 **end)
+{
+	size_t bytes;
+	const __be32 *cur;
+
+	cur = of_get_property(np, list_name, &bytes);
+	*end = cur;
+	if (bytes)
+		*end += bytes / sizeof(*cur);
+
+	return cur;
+}
+EXPORT_SYMBOL_GPL(of_phandle_iter_init);
+
 static int __of_parse_phandle_with_args(const struct device_node *np,
 					const char *list_name,
 					const char *cells_name,

diff --git a/include/linux/of.h b/include/linux/of.h
index 276c546..4345582 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h

@@ -303,6 +303,14 @@ extern int of_parse_phandle_with_fixed_args(const struct device_node *np,
 extern int of_count_phandle_with_args(const struct device_node *np,
 	const char *list_name, const char *cells_name);
 
+extern const __be32 *of_phandle_iter_init(const struct device_node *np,
+					  const char *list_name,
+					  const __be32 **end);
+extern const __be32 *of_phandle_iter_next(const char *cells_name,
+					  int cell_count,
+					  const __be32 *cur, const __be32 *end,
+					  struct of_phandle_args *out_args);
+
 extern void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align));
 extern int of_alias_get_id(struct device_node *np, const char *stem);
 

@@ -527,6 +535,22 @@ static inline int of_count_phandle_with_args(struct device_node *np,
 	return -ENOSYS;
 }
 
+static inline const __be32 *of_phandle_iter_init(const struct device_node *np,
+						 const char *list_name,
+						 const __be32 **end)
+{
+	return NULL;
+}
+
+static inline const __be32 *of_phandle_iter_next(const char *cells_name,
+						 int cell_count,
+						 const __be32 *cur,
+						 const __be32 *end,
+						 struct of_phandle_args *out_args);
+{
+	return NULL;
+}
+
 static inline int of_alias_get_id(struct device_node *np, const char *stem)
 {
 	return -ENOSYS;

@@ -613,6 +637,14 @@ static inline int of_property_read_u32(const struct device_node *np,
 		s;						\
 		s = of_prop_next_string(prop, s))
 
+#define of_property_for_each_phandle_with_args(node, list_name, cells_name, \
+					       cell_count, out_args, cur, end) \
+	for (cur = of_phandle_iter_init(node, list_name, &end),		\
+		     cur = of_phandle_iter_next(cells_name, cell_count, \
+						cur, end, &out_args);	\