of: add functions to count number of elements in a property
From: Heiko Stuebner <heiko@...> Date: Thu, 16 Jan 2014 18:26:28 +0100
Commit-Message
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@...> Signed-off-by: Heiko Stuebner <heiko@...>
Patch-Comment
This is the same as v4 when this patch was separate, that was a result of the discussion in in v6 of the rockchip-smp series. drivers/of/base.c | 32 ++++++++++++++++++++++ include/linux/of.h | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 108 insertions(+)
Statistics
- 108 lines added
- 0 lines removed
Changes
------------------------------ drivers/of/base.c -------------------------------
index 8d007d8..d08acbc 100644
@@ -883,6 +883,38 @@ 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.
------------------------------ include/linux/of.h ------------------------------
index 70c64ba..b59f2e4 100644
@@ -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)
{
@@ -570,6 +578,74 @@ 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.
* @propname: name of the property to be searched.