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; +} + +/** + * 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); + +/** + * 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. + */ +int of_property_count_u16_elems(const struct device_node *np, + const char *propname) +{ + return of_count_property_elems_of_size(np, propname, sizeof(u16)); +} +EXPORT_SYMBOL_GPL(of_property_count_u16_elems); + +/** + * 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. + */ +int of_property_count_u32_elems(const struct device_node *np, + const char *propname) +{ + return of_count_property_elems_of_size(np, propname, sizeof(u32)); +} +EXPORT_SYMBOL_GPL(of_property_count_u32_elems); + +/** + * 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. + */ +int of_property_count_u64_elems(const struct device_node *np, + const char *propname) +{ + return of_count_property_elems_of_size(np, propname, sizeof(u64)); +} +EXPORT_SYMBOL_GPL(of_property_count_u64_elems); + +/** * of_find_property_value_of_size * * @np: device node from which the property value is to be read. diff --git a/include/linux/of.h b/include/linux/of.h index 276c546..06fe898 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -250,6 +250,14 @@ 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_u8_elems(const struct device_node *np, + const char *propname); +extern int of_property_count_u16_elems(const struct device_node *np, + const char *propname); +extern int of_property_count_u32_elems(const struct device_node *np, + const char *propname); +extern int of_property_count_u64_elems(const struct device_node *np, + const char *propname); extern int of_property_read_u32_index(const struct device_node *np, const char *propname, u32 index, u32 *out_value); @@ -426,6 +434,30 @@ static inline struct device_node *of_find_compatible_node( return NULL; } +static inline int of_property_count_u8_elems(const struct device_node *np, + const char *propname) +{ + return -ENOSYS; +} + +static inline int of_property_count_u16_elems(const struct device_node *np, + const char *propname) +{ + return -ENOSYS; +} + +static inline int of_property_count_u32_elems(const struct device_node *np, + const char *propname) +{ + return -ENOSYS; +} + +static inline int of_property_count_u64_elems(const struct device_node *np, + const char *propname) +{ + return -ENOSYS; +} + static inline int of_property_read_u32_index(const struct device_node *np, const char *propname, u32 index, u32 *out_value) { -- 1.7.10.4 -- 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