On Fri, Jan 17, 2014 at 9:44 AM, Heiko Stübner <heiko@xxxxxxxxx> wrote:
> 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@xxxxxxx>
> Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
> ---
> changes since v1:
> address comments from Rob Herring and Mark Rutland:
> - provide a helper and a set of wrappers for u8-u64
> - get rid of extra len variable, prop->length is enough
> - include node name in error message
>
> drivers/of/base.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/of.h | 32 +++++++++++++++++
> 2 files changed, 130 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index f807d0e..b6e6d4a 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -862,6 +862,104 @@ struct device_node *of_find_node_by_phandle(phandle handle)
> EXPORT_SYMBOL(of_find_node_by_phandle);
>
> /**
> + * of_count_property_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
> + */
> +static int of_count_property_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->name, elem_size);
> + return -EINVAL;
> + }
> +
> + return prop->length / elem_size;
> +}
Export this one.
> +
> +/**
> + * 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.
> + */
> +int of_property_count_u8_elems(const struct device_node *np,
> + const char *propname)
> +{
> + return of_count_property_elems_of_size(np, propname, sizeof(u8));
> +}
> +EXPORT_SYMBOL_GPL(of_property_count_u8_elems);
And make all these static inline.
Then you only need a single empty function for !OF.
Rob
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
