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of: base: add of_parse_phandle_with_optional_args() 

Add a new variant of the of_parse_phandle_with_args() which treats the
cells name as optional. If it's missing, it is assumed that the phandle
has no arguments.

Up until now, a nvmem node didn't have any arguments, so all the device
trees haven't any '#*-cells' property. But there is a need for an
additional argument for the phandle, for which we need a '#*-cells'
property. Therefore, we need to support nvmem nodes with and without
this property.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20230206134356.839737-10-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Walle 2023-02-06 13:43:43 +00:00 committed by Greg Kroah-Hartman
parent 7390609b01
commit c5d264d4b5
1 changed files with 25 additions and 0 deletions
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25
include/linux/of.h
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@ -1008,6 +1008,31 @@ static inline int of_parse_phandle_with_fixed_args(const struct device_node *np,
index, out_args);
}
/**
* of_parse_phandle_with_optional_args() - Find a node pointed by phandle in a list
* @np: pointer to a device tree node containing a list
* @list_name: property name that contains a list
* @cells_name: property name that specifies phandles' arguments count
* @index: index of a phandle to parse out
* @out_args: optional pointer to output arguments structure (will be filled)
*
* Same as of_parse_phandle_with_args() except that if the cells_name property
* is not found, cell_count of 0 is assumed.
*
* This is used to useful, if you have a phandle which didn't have arguments
* before and thus doesn't have a '#*-cells' property but is now migrated to
* having arguments while retaining backwards compatibility.
*/
static inline int of_parse_phandle_with_optional_args(const struct device_node *np,
const char *list_name,
const char *cells_name,
int index,
struct of_phandle_args *out_args)
{
return __of_parse_phandle_with_args(np, list_name, cells_name,
0, index, out_args);
}
/**
* of_property_count_u8_elems - Count the number of u8 elements in a property
*