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Message-ID: <20131202.130220.1404999403649937134.hdoyu@nvidia.com>
Date: Mon, 2 Dec 2013 12:02:20 +0100
From: Hiroshi Doyu <hdoyu@...dia.com>
To: "swarren@...dotorg.org" <swarren@...dotorg.org>
CC: "grant.likely@...aro.org" <grant.likely@...aro.org>,
"thierry.reding@...il.com" <thierry.reding@...il.com>,
"robherring2@...il.com" <robherring2@...il.com>,
"joro@...tes.org" <joro@...tes.org>,
Stephen Warren <swarren@...dia.com>,
"will.deacon@....com" <will.deacon@....com>,
"mark.rutland@....com" <mark.rutland@....com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
"galak@...eaurora.org" <galak@...eaurora.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC][PATCHv6+++ 01/13] of: introduce
of_property_for_earch_phandle_with_args()
Stephen Warren <swarren@...dotorg.org> wrote @ Sun, 1 Dec 2013 20:00:09 +0100:
> On 11/29/2013 04:46 AM, Hiroshi Doyu wrote:
> ...
> > 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.
> >
> > Introduced a new struct "of_phandle_iter" to keep the state when
> > iterating over the list.
> >
> > Signed-off-by: Hiroshi Doyu <hdoyu@...dia.com>
> > ---
> > v6+++:
>
> Surely that's v9; "+++" is rather unusual.
My intention was to put this into the next v7 series after I get this
reviewed as RFC.
...
> Together with removing:
>
> > + const char *cells_name;
> > + int cell_count;
>
> ... then you'd only be left with cur/end, so I think you could get away
> without a struct at all, but simply "cur" as the iterator variable, plus
> "end" as the one temp variable.
Although the above proposal would be alsmot same as "[RFC][PATCHv6++
01/13]"(*1) where I use *list(cur) and rem as remaining count, here's
the update. I'll put this into v7 series.
---8<------8<------8<------8<------8<------8<------8<------8<------8<---
From: Hiroshi Doyu <hdoyu@...dia.com>
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 <hdoyu@...dia.com>
---
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 <hdoyu@...dia.com>
---
drivers/of/base.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/of.h | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 87 insertions(+)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index f807d0e..7501f24 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1201,6 +1201,59 @@ 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)
+{
+ phandle phandle;
+ struct device_node *dn;
+ int i;
+
+ if (!cells_name && !cell_count)
+ return NULL;
+
+ if (!cur)
+ return NULL;
+
+ if (end - cur <= 0)
+ return NULL;
+
+ phandle = be32_to_cpup(cur++);
+ if (!phandle)
+ return NULL;
+
+ dn = of_find_node_by_phandle(phandle);
+ 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);
+ if (bytes)
+ *end = cur + 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..c23710b 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 +535,24 @@ 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 char *cells_name,
+ const int cell_count,
+ struct of_phandle_args *out_args)
+{
+ 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 +639,14 @@ 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); \
+ cur; \
+ cur = of_phandle_iter_next(cells_name, cell_count, cur, end, &out_args))
+
#if defined(CONFIG_PROC_FS) && defined(CONFIG_PROC_DEVICETREE)
extern void proc_device_tree_add_node(struct device_node *, struct proc_dir_entry *);
extern void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop);
--
1.8.1.5
*1:
http://lists.linuxfoundation.org/pipermail/iommu/2013-November/007086.html
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