On 15/10/2020 17:52, Robin Murphy wrote:
On 2020-10-14 19:39, Rob Herring wrote:
On Wed, Oct 14, 2020 at 9:54 AM Richard Fitzgerald
<rf@xxxxxxxxxxxxxxxxxxxxx> wrote:
Add an equivalent of of_count_phandle_with_args() for fixed argument
sets, to pair with of_parse_phandle_with_fixed_args().
Signed-off-by: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/of/base.c | 42 ++++++++++++++++++++++++++++++++++++++++++
include/linux/of.h | 9 +++++++++
2 files changed, 51 insertions(+)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index ea44fea99813..45d8b0e65345 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1772,6 +1772,48 @@ int of_count_phandle_with_args(const struct
device_node *np, const char *list_na
}
EXPORT_SYMBOL(of_count_phandle_with_args);
+/**
+ * of_count_phandle_with_fixed_args() - Find the number of phandles
references in a property
+ * @np: pointer to a device tree node containing a list
+ * @list_name: property name that contains a list
+ * @cell_count: number of argument cells following the phandle
+ *
+ * Returns the number of phandle + argument tuples within a
property. It
+ * is a typical pattern to encode a list of phandle and variable
+ * arguments into a single property.
+ */
+int of_count_phandle_with_fixed_args(const struct device_node *np,
+ const char *list_name,
+ int cells_count)
+{
Looks to me like you can refactor of_count_phandle_with_args to handle
both case and then make this and of_count_phandle_with_args simple
wrapper functions.
Although for just counting the number of phandles each with n arguments
that a property contains, isn't that simply a case of dividing the
property length by n + 1? The phandles themselves will be validated by
any subsequent of_parse_phandle*() call anyway, so there doesn't seem
much point in doing more work then necessary here.
As I'm not a DT expert, I'm reluctant to change existing algorithms that
could break everything just for the trivial case of adding a fixed
arguments count. I have a re-worked patch as suggested by Rob that
re-uses the existing counting function for both cases.
+ struct of_phandle_iterator it;
+ int rc, cur_index = 0;
+
+ if (!cells_count) {
+ const __be32 *list;
+ int size;
+
+ list = of_get_property(np, list_name, &size);
+ if (!list)
+ return -ENOENT;
+
+ return size / sizeof(*list);
Case in point - if it's OK to do exactly that for n == 0, then clearly
we're *aren't* fussed about validating anything, so the n > 0 code below
is nothing more than a massively expensive way to check for a nonzero
remainder :/
Robin.
+ }
+
+ rc = of_phandle_iterator_init(&it, np, list_name, NULL,
cells_count);
+ if (rc)
+ return rc;
+
+ while ((rc = of_phandle_iterator_next(&it)) == 0)
+ cur_index += 1;
+
+ if (rc != -ENOENT)
+ return rc;
+
+ return cur_index;
+}
+EXPORT_SYMBOL(of_count_phandle_with_fixed_args);
+
/**
* __of_add_property - Add a property to a node without lock
operations
*/
diff --git a/include/linux/of.h b/include/linux/of.h
index 5cf7ae0465d1..9f315da4e9da 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -377,6 +377,8 @@ extern int of_parse_phandle_with_fixed_args(const
struct device_node *np,
struct of_phandle_args *out_args);
extern int of_count_phandle_with_args(const struct device_node *np,
const char *list_name, const char *cells_name);
+extern int of_count_phandle_with_fixed_args(const struct device_node
*np,
+ const char *list_name, int cells_count);
/* phandle iterator functions */
extern int of_phandle_iterator_init(struct of_phandle_iterator *it,
@@ -886,6 +888,13 @@ static inline int
of_count_phandle_with_args(struct device_node *np,
return -ENOSYS;
}
+static inline int of_count_phandle_with_fixed_args(const struct
device_node *np,
+ const char
*list_name,
+ int cells_count)
+{
+ return -ENOSYS;
+}
+
static inline int of_phandle_iterator_init(struct
of_phandle_iterator *it,
const struct device_node
*np,
const char *list_name,
--
2.20.1
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