Hiroshi Doyu [off-list ref] wrote @ Thu, 12 Dec 2013 14:14:04 +0200 (EET):

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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>

....

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---
 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)

Having to pass in cells_name, cell_count, cur and end each time seems a
little odd. Can a state structure be used instead?

struct of_phandle_iter_state {
        const char *cells_name;
        int cells_count;
        const __be32 *cur;
        const __be32 *end;
        struct of_phandle_args out_args;
}

Make the caller provide one of those and fill it in with the init
function.

I rewrote this a few times and so now I have a few version of this
implementations :-) The above proposal is similar to the version v6+++
mentioned in the above patch note:

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

which is:

  [RFC][PATCHv6+++ 01/13] of: introduce of_property_for_earch_phandle_with_args()
    http://lists.linuxfoundation.org/pipermail/iommu/2013-November/007087.html

Stephen seemed to prefer the version without state struct. I like the
idea to not pass the same arguments repeatly. Instead, wrapping them
in a struct with state may look better.

So if Stephen agrees, I'll rewrite the version with state struct
again.

Stephen, let me know what you think.