linux-kernel - [PATCH 1/2] of: Make of_find_property_value_of

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Date:   Tue, 6 Sep 2016 16:02:00 +0100
From:   Richard Fitzgerald <rf@...nsource.wolfsonmicro.com>
To:     <robh+dt@...nel.org>, <frowand.list@...il.com>
CC:     <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <patches@...nsource.wolfsonmicro.com>
Subject: [PATCH 1/2] of: Make of_find_property_value_of_size take a length range

In preparation for adding variable-length array reads, change
of_find_property_value_of_size so that it takes an optional
maximum length. If the maximum is passed as 0, the behaviour is
unchanged and it will return a property if it's >= the requested
minimum length. If maximum is non-zero it will only return a
property whose length is min <= l <= max.

Signed-off-by: Richard Fitzgerald <rf@...nsource.wolfsonmicro.com>
---
 drivers/of/base.c | 39 +++++++++++++++++++++++++++++----------
 1 file changed, 29 insertions(+), 10 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 3ce6953..b853737 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1146,16 +1146,18 @@ EXPORT_SYMBOL_GPL(of_property_count_elems_of_size);
  *
  * @np:		device node from which the property value is to be read.
  * @propname:	name of the property to be searched.
- * @len:	requested length of property value
+ * @min:	minimum allowed length of property value
+ * @max:	maximum allowed length of property value (0 means unlimited)
+ * @len:	if !=NULL, actual length is written to here
  *
  * Search for a property in a device node and valid the requested size.
  * Returns the property value on success, -EINVAL if the property does not
  *  exist, -ENODATA if property does not have a value, and -EOVERFLOW if the
- * property data isn't large enough.
+ * property data is too small or too large.
  *
  */
 static void *of_find_property_value_of_size(const struct device_node *np,
-			const char *propname, u32 len)
+			const char *propname, u32 min, u32 max, size_t *len)
 {
 	struct property *prop = of_find_property(np, propname, NULL);
 
@@ -1163,8 +1165,13 @@ static void *of_find_property_value_of_size(const struct device_node *np,
 		return ERR_PTR(-EINVAL);
 	if (!prop->value)
 		return ERR_PTR(-ENODATA);
-	if (len > prop->length)
+	if (prop->length < min)
 		return ERR_PTR(-EOVERFLOW);
+	if (max && prop->length > max)
+		return ERR_PTR(-EOVERFLOW);
+
+	if (len)
+		*len = prop->length;
 
 	return prop->value;
 }
@@ -1189,7 +1196,9 @@ int of_property_read_u32_index(const struct device_node *np,
 				       u32 index, u32 *out_value)
 {
 	const u32 *val = of_find_property_value_of_size(np, propname,
-					((index + 1) * sizeof(*out_value)));
+					((index + 1) * sizeof(*out_value)),
+					0,
+					NULL);
 
 	if (IS_ERR(val))
 		return PTR_ERR(val);
@@ -1221,7 +1230,9 @@ int of_property_read_u8_array(const struct device_node *np,
 			const char *propname, u8 *out_values, size_t sz)
 {
 	const u8 *val = of_find_property_value_of_size(np, propname,
-						(sz * sizeof(*out_values)));
+						(sz * sizeof(*out_values)),
+						0,
+						NULL);
 
 	if (IS_ERR(val))
 		return PTR_ERR(val);
@@ -1254,7 +1265,9 @@ int of_property_read_u16_array(const struct device_node *np,
 			const char *propname, u16 *out_values, size_t sz)
 {
 	const __be16 *val = of_find_property_value_of_size(np, propname,
-						(sz * sizeof(*out_values)));
+						(sz * sizeof(*out_values)),
+						0,
+						NULL);
 
 	if (IS_ERR(val))
 		return PTR_ERR(val);
@@ -1286,7 +1299,9 @@ int of_property_read_u32_array(const struct device_node *np,
 			       size_t sz)
 {
 	const __be32 *val = of_find_property_value_of_size(np, propname,
-						(sz * sizeof(*out_values)));
+						(sz * sizeof(*out_values)),
+						0,
+						NULL);
 
 	if (IS_ERR(val))
 		return PTR_ERR(val);
@@ -1314,7 +1329,9 @@ int of_property_read_u64(const struct device_node *np, const char *propname,
 			 u64 *out_value)
 {
 	const __be32 *val = of_find_property_value_of_size(np, propname,
-						sizeof(*out_value));
+						sizeof(*out_value),
+						0,
+						NULL);
 
 	if (IS_ERR(val))
 		return PTR_ERR(val);
@@ -1345,7 +1362,9 @@ int of_property_read_u64_array(const struct device_node *np,
 			       size_t sz)
 {
 	const __be32 *val = of_find_property_value_of_size(np, propname,
-						(sz * sizeof(*out_values)));
+						(sz * sizeof(*out_values)),
+						0,
+						NULL);
 
 	if (IS_ERR(val))
 		return PTR_ERR(val);
-- 
1.9.1