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Commit ad54a0cf authored by Heiko Stuebner's avatar Heiko Stuebner Committed by Mark Brown
Browse files

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



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: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarHeiko Stuebner <heiko.stuebner@bqreaders.com>
Acked-by: default avatarRob Herring <robh@kernel.org>
Acked-by: default avatarGrant Likely <grant.likely@linaro.org>
Acked-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarMark Brown <broonie@linaro.org>
parent 38dbfb59

drivers/of/base.c

+32 −0
Original line number Diff line number Diff line
@@ -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

 *

include/linux/of.h

+76 −0
Original line number Diff line number Diff line
@@ -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.