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author | Heiko Stuebner <heiko.stuebner@bqreaders.com> | 2014-02-12 01:00:34 +0100 |
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committer | Mark Brown <broonie@linaro.org> | 2014-02-12 16:48:48 +0100 |
commit | ad54a0cfbeb4bd4033d09017557ccbc423f9d5ff (patch) | |
tree | 673298cf99ab63d9bc0ab19b705537966d65e2e3 /drivers/of | |
parent | Linus 3.14-rc1 (diff) | |
download | linux-ad54a0cfbeb4bd4033d09017557ccbc423f9d5ff.tar.xz linux-ad54a0cfbeb4bd4033d09017557ccbc423f9d5ff.zip |
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: 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>
Diffstat (limited to 'drivers/of')
-rw-r--r-- | drivers/of/base.c | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/drivers/of/base.c b/drivers/of/base.c index ff85450d5683..8a2a55c65e5d 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -886,6 +886,38 @@ 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 * * @np: device node from which the property value is to be read. |