reset: Add reset_control_get_count()

Currently the reset core has internal support for counting the number of
resets for a device described in DT.  Generalize this to devices using
lookup resets, and export it for public use.

This will be used by generic drivers that need to be sure a device is
controlled by a single, dedicated reset line (e.g. vfio-platform).

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
[p.zabel@pengutronix.de: fixed a typo in reset_control_get_count comment]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index d1887c0..bce2d6a 100644 (file)
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -795,3 +795,44 @@ devm_reset_control_array_get(struct device *dev, bool shared, bool optional)
        return rstc;
 }
 EXPORT_SYMBOL_GPL(devm_reset_control_array_get);
+
+static int reset_control_get_count_from_lookup(struct device *dev)
+{
+       const struct reset_control_lookup *lookup;
+       const char *dev_id = dev_name(dev);
+       int count = 0;
+
+       if (!dev)
+               return -EINVAL;
+
+       mutex_lock(&reset_lookup_mutex);
+
+       list_for_each_entry(lookup, &reset_lookup_list, list) {
+               if (!strcmp(lookup->dev_id, dev_id))
+                       count++;
+       }
+
+       mutex_unlock(&reset_lookup_mutex);
+
+       if (count == 0)
+               count = -ENOENT;
+
+       return count;
+}
+
+/**
+ * reset_control_get_count - Count number of resets available with a device
+ *
+ * @dev: device for which to return the number of resets
+ *
+ * Returns positive reset count on success, or error number on failure and
+ * on count being zero.
+ */
+int reset_control_get_count(struct device *dev)
+{
+       if (dev->of_node)
+               return of_reset_control_get_count(dev->of_node);
+
+       return reset_control_get_count_from_lookup(dev);
+}
+EXPORT_SYMBOL_GPL(reset_control_get_count);

diff --git a/include/linux/reset.h b/include/linux/reset.h
index 76690cf..c1901b6 100644 (file)
--- a/include/linux/reset.h
+++ b/include/linux/reset.h
@@ -32,6 +32,8 @@ struct reset_control *devm_reset_control_array_get(struct device *dev,
 struct reset_control *of_reset_control_array_get(struct device_node *np,
                                                 bool shared, bool optional);
 
+int reset_control_get_count(struct device *dev);
+
 #else
 
 static inline int reset_control_reset(struct reset_control *rstc)
@@ -97,6 +99,11 @@ of_reset_control_array_get(struct device_node *np, bool shared, bool optional)
        return optional ? NULL : ERR_PTR(-ENOTSUPP);
 }
 
+static inline int reset_control_get_count(struct device *dev)
+{
+       return -ENOENT;
+}
+
 #endif /* CONFIG_RESET_CONTROLLER */
 
 static inline int __must_check device_reset(struct device *dev)