dt: add property iteration helpers

This patch adds macros of_property_for_each_u32() and
of_property_for_each_string(), which iterate over an array of values
within a device-tree property. Usage is for example:

struct property *prop;
const __be32 *p;
u32 u;
of_property_for_each_u32(np, "propname", prop, p, u)
	printk("U32 value: %x\n", u);

struct property *prop;
const char *s;
of_property_for_each_string(np, "propname", prop, s)
	printk("String value: %s\n", s);

Based on work by Rob Herring <robherring2@gmail.com>

Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 41 insertions, 0 deletions

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 580644986945..d9bfd49b1935 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1260,3 +1260,44 @@ int of_alias_get_id(struct device_node *np, const char *stem)
         return id;
 }
 EXPORT_SYMBOL_GPL(of_alias_get_id);
+
+const __be32 *of_prop_next_u32(struct property *prop, const __be32 *cur,
+                               u32 *pu)
+{
+        const void *curv = cur;
+
+        if (!prop)
+                return NULL;
+
+        if (!cur) {
+                curv = prop->value;
+                goto out_val;
+        }
+
+        curv += sizeof(*cur);
+        if (curv >= prop->value + prop->length)
+                return NULL;
+
+out_val:
+        *pu = be32_to_cpup(curv);
+        return curv;
+}
+EXPORT_SYMBOL_GPL(of_prop_next_u32);
+
+const char *of_prop_next_string(struct property *prop, const char *cur)
+{
+        const void *curv = cur;
+
+        if (!prop)
+                return NULL;
+
+        if (!cur)
+                return prop->value;
+
+        curv += strlen(cur) + 1;
+        if (curv >= prop->value + prop->length)
+                return NULL;
+
+        return curv;
+}
+EXPORT_SYMBOL_GPL(of_prop_next_string);