[LTSI-3.14,335/894] of: add functions to count number of elements in a property

Commit Message

Simon Horman Aug. 28, 2014, 6:57 a.m. UTC

From: Heiko Stuebner <[e-mail]>

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 <[e-mail]>
Signed-off-by: Heiko Stuebner <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Acked-by: Grant Likely <[e-mail]>
Acked-by: Mark Rutland <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>
(cherry picked from commit ad54a0cfbeb4bd4033d09017557ccbc423f9d5ff)
Signed-off-by: Simon Horman <[e-mail]>
---
 drivers/of/base.c  | 32 +++++++++++++++++++++++
 include/linux/of.h | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 108 insertions(+)

Patch

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 89e888a..1b95a40 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -904,6 +904,38 @@  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.
diff --git a/include/linux/of.h b/include/linux/of.h
index 435cb99..83d1ac8 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -198,6 +198,8 @@  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);
@@ -390,6 +392,12 @@  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)
 {
@@ -536,6 +544,74 @@  static inline struct device_node *of_find_matching_node(
 }
 
 /**
+ * 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.