target/linux/generic/backport-5.15/827-v6.3-0001-of-base-add-of_parse_phandle_with_optional_args.patch

   1 From c5d264d4b527c96ae8903376a4b195df47b05203 Mon Sep 17 00:00:00 2001
   2 From: Michael Walle <michael@walle.cc>
   3 Date: Mon, 6 Feb 2023 13:43:43 +0000
   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 Link: https://lore.kernel.org/r/20230206134356.839737-10-srinivas.kandagatla@linaro.org
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21 ---
  22  include/linux/of.h | 25 +++++++++++++++++++++++++
  23  1 file changed, 25 insertions(+)
  24
  25 --- a/include/linux/of.h
  26 +++ b/include/linux/of.h
  27 @@ -1019,6 +1019,31 @@ static inline int of_parse_phandle_with_
  28  }
  29
  30  /**
  31 + * of_parse_phandle_with_optional_args() - Find a node pointed by phandle in a list
  32 + * @np:                pointer to a device tree node containing a list
  33 + * @list_name: property name that contains a list
  34 + * @cells_name:        property name that specifies phandles' arguments count
  35 + * @index:     index of a phandle to parse out
  36 + * @out_args:  optional pointer to output arguments structure (will be filled)
  37 + *
  38 + * Same as of_parse_phandle_with_args() except that if the cells_name property
  39 + * is not found, cell_count of 0 is assumed.
  40 + *
  41 + * This is used to useful, if you have a phandle which didn't have arguments
  42 + * before and thus doesn't have a '#*-cells' property but is now migrated to
  43 + * having arguments while retaining backwards compatibility.
  44 + */
  45 +static inline int of_parse_phandle_with_optional_args(const struct device_node *np,
  46 +                                                     const char *list_name,
  47 +                                                     const char *cells_name,
  48 +                                                     int index,
  49 +                                                     struct of_phandle_args *out_args)
  50 +{
  51 +       return __of_parse_phandle_with_args(np, list_name, cells_name,
  52 +                                           0, index, out_args);
  53 +}
  54 +
  55 +/**
  56   * of_property_count_u8_elems - Count the number of u8 elements in a property
  57   *
  58   * @np:                device node from which the property value is to be read.