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of: add functions to count number of elements in a property

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The need to know the number of array elements in a property is
a common pattern. To prevent duplication of open-coded implementations
add a helper static function that also centralises strict sanity
checking and DTB format details, as well as a set of wrapper functions
for u8, u16, u32 and u64.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Heiko Stuebner <heiko.stuebner@bqreaders.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
This commit is contained in:
Heiko Stuebner 2014-02-12 01:00:34 +01:00 committed by Mark Brown
parent 38dbfb59d1
commit ad54a0cfbe
2 changed files with 108 additions and 0 deletions
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32
drivers/of/base.c
View File

@ -885,6 +885,38 @@ struct device_node *of_find_node_by_phandle(phandle handle)
}
EXPORT_SYMBOL(of_find_node_by_phandle);
/**
* of_property_count_elems_of_size - Count the number of elements in a property
*
* @np: device node from which the property value is to be read.
* @propname: name of the property to be searched.
* @elem_size: size of the individual element
*
* Search for a property in a device node and count the number of elements of
* size elem_size in it. Returns number of elements on sucess, -EINVAL if the
* property does not exist or its length does not match a multiple of elem_size
* and -ENODATA if the property does not have a value.
*/
int of_property_count_elems_of_size(const struct device_node *np,
const char *propname, int elem_size)
{
struct property *prop = of_find_property(np, propname, NULL);
if (!prop)
return -EINVAL;
if (!prop->value)
return -ENODATA;
if (prop->length % elem_size != 0) {
pr_err("size of %s in node %s is not a multiple of %d\n",
propname, np->full_name, elem_size);
return -EINVAL;
}
return prop->length / elem_size;
}
EXPORT_SYMBOL_GPL(of_property_count_elems_of_size);
/**
* of_find_property_value_of_size
*

76
include/linux/of.h
View File

@ -250,6 +250,8 @@ extern struct device_node *of_find_node_with_property(
extern struct property *of_find_property(const struct device_node *np,
const char *name,
int *lenp);
extern int of_property_count_elems_of_size(const struct device_node *np,
const char *propname, int elem_size);
extern int of_property_read_u32_index(const struct device_node *np,
const char *propname,
u32 index, u32 *out_value);
@ -431,6 +433,12 @@ static inline struct device_node *of_find_compatible_node(
return NULL;
}
static inline int of_property_count_elems_of_size(const struct device_node *np,
const char *propname, int elem_size)
{
return -ENOSYS;
}
static inline int of_property_read_u32_index(const struct device_node *np,
const char *propname, u32 index, u32 *out_value)
{
@ -569,6 +577,74 @@ extern int of_node_to_nid(struct device_node *np);
static inline int of_node_to_nid(struct device_node *device) { return 0; }
#endif
/**
* of_property_count_u8_elems - Count the number of u8 elements in a property
*
* @np: device node from which the property value is to be read.
* @propname: name of the property to be searched.
*
* Search for a property in a device node and count the number of u8 elements
* in it. Returns number of elements on sucess, -EINVAL if the property does
* not exist or its length does not match a multiple of u8 and -ENODATA if the
* property does not have a value.
*/
static inline int of_property_count_u8_elems(const struct device_node *np,
const char *propname)
{
return of_property_count_elems_of_size(np, propname, sizeof(u8));
}
/**
* of_property_count_u16_elems - Count the number of u16 elements in a property
*
* @np: device node from which the property value is to be read.
* @propname: name of the property to be searched.
*
* Search for a property in a device node and count the number of u16 elements
* in it. Returns number of elements on sucess, -EINVAL if the property does
* not exist or its length does not match a multiple of u16 and -ENODATA if the
* property does not have a value.
*/
static inline int of_property_count_u16_elems(const struct device_node *np,
const char *propname)
{
return of_property_count_elems_of_size(np, propname, sizeof(u16));
}
/**
* of_property_count_u32_elems - Count the number of u32 elements in a property
*
* @np: device node from which the property value is to be read.
* @propname: name of the property to be searched.
*
* Search for a property in a device node and count the number of u32 elements
* in it. Returns number of elements on sucess, -EINVAL if the property does
* not exist or its length does not match a multiple of u32 and -ENODATA if the
* property does not have a value.
*/
static inline int of_property_count_u32_elems(const struct device_node *np,
const char *propname)
{
return of_property_count_elems_of_size(np, propname, sizeof(u32));
}
/**
* of_property_count_u64_elems - Count the number of u64 elements in a property
*
* @np: device node from which the property value is to be read.
* @propname: name of the property to be searched.
*
* Search for a property in a device node and count the number of u64 elements
* in it. Returns number of elements on sucess, -EINVAL if the property does
* not exist or its length does not match a multiple of u64 and -ENODATA if the
* property does not have a value.
*/
static inline int of_property_count_u64_elems(const struct device_node *np,
const char *propname)
{
return of_property_count_elems_of_size(np, propname, sizeof(u64));
}
/**
* of_property_read_bool - Findfrom a property
* @np: device node from which the property value is to be read.