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Subject[PATCH] reset: Add reset_control_get_count()
Date
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>
---
See https://lore.kernel.org/lkml/1539003437.11512.20.camel@pengutronix.de/
for the rationale to ensure a single, dedicated reset line.

drivers/reset/core.c | 41 +++++++++++++++++++++++++++++++++++++++++
include/linux/reset.h | 7 +++++++
2 files changed, 48 insertions(+)

diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index 654e20ff2d5da9d4..c32b755ec373c338 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -859,3 +859,44 @@ 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;
+}
+
+/**
+ * of_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 f0b094130686bf32..2698b36bd1eb3e0c 100644
--- 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)
--
2.17.1
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