target/linux/generic/backport-5.10/827-v6.3-0001-of-base-add-of_parse_phandle_with_optional_args.patch

   1 From 8eddceb280f5deb8046fcb660de9f9f683b408b9 Mon Sep 17 00:00:00 2001
   2 From: Michael Walle <michael@walle.cc>
   3 Date: Tue, 6 Dec 2022 21:07:21 +0100
   4 Subject: [PATCH] of: base: add of_parse_phandle_with_optional_args()
   5
   6 Add a new variant of the of_parse_phandle_with_args() which treats the
   7 cells name as optional. If it's missing, it is assumed that the phandle
   8 has no arguments.
   9
  10 Up until now, a nvmem node didn't have any arguments, so all the device
  11 trees haven't any '#*-cells' property. But there is a need for an
  12 additional argument for the phandle, for which we need a '#*-cells'
  13 property. Therefore, we need to support nvmem nodes with and without
  14 this property.
  15
  16 Signed-off-by: Michael Walle <michael@walle.cc>
  17 Reviewed-by: Rob Herring <robh@kernel.org>
  18 Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
  19 ---
  20  include/linux/of.h | 25 +++++++++++++++++++++++++
  21  1 file changed, 25 insertions(+)
  22
  23 --- a/include/linux/of.h
  24 +++ b/include/linux/of.h
  25 @@ -1157,6 +1157,31 @@ static inline int of_parse_phandle_with_
  26  }
  27
  28  /**
  29 + * of_parse_phandle_with_optional_args() - Find a node pointed by phandle in a list
  30 + * @np:                pointer to a device tree node containing a list
  31 + * @list_name: property name that contains a list
  32 + * @cells_name:        property name that specifies phandles' arguments count
  33 + * @index:     index of a phandle to parse out
  34 + * @out_args:  optional pointer to output arguments structure (will be filled)
  35 + *
  36 + * Same as of_parse_phandle_with_args() except that if the cells_name property
  37 + * is not found, cell_count of 0 is assumed.
  38 + *
  39 + * This is used to useful, if you have a phandle which didn't have arguments
  40 + * before and thus doesn't have a '#*-cells' property but is now migrated to
  41 + * having arguments while retaining backwards compatibility.
  42 + */
  43 +static inline int of_parse_phandle_with_optional_args(const struct device_node *np,
  44 +                                                     const char *list_name,
  45 +                                                     const char *cells_name,
  46 +                                                     int index,
  47 +                                                     struct of_phandle_args *out_args)
  48 +{
  49 +       return __of_parse_phandle_with_args(np, list_name, cells_name,
  50 +                                           0, index, out_args);
  51 +}
  52 +
  53 +/**
  54   * of_property_count_u8_elems - Count the number of u8 elements in a property
  55   *
  56   * @np:                device node from which the property value is to be read.