reset: modify the way reset lookup works for board files

Commit 7af1bb19f1d7 ("reset: add support for non-DT systems")
introduced reset control lookup mechanism for boards that still use
board files.

The routine used to register lookup entries takes the corresponding
reset_controlled_dev structure as argument.

It's been determined however that for the first user of this new
interface - davinci psc driver - it will be easier to register the
lookup entries using the reset controller device name.

This patch changes the way lookup entries are added.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
[p.zabel@pengutronix.de: added missing ERR_PTR]
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

drivers/reset/core.c

@@ -153,12 +153,10 @@ EXPORT_SYMBOL_GPL(devm_reset_controller_register);
 
 /**
  * reset_controller_add_lookup - register a set of lookup entries
- * @rcdev: initialized reset controller device owning the reset line
  * @lookup: array of reset lookup entries
  * @num_entries: number of entries in the lookup array
  */
-void reset_controller_add_lookup(struct reset_controller_dev *rcdev,
-				 struct reset_control_lookup *lookup,
+void reset_controller_add_lookup(struct reset_control_lookup *lookup,
 				 unsigned int num_entries)
 {
 	struct reset_control_lookup *entry;
@@ -168,13 +166,12 @@ void reset_controller_add_lookup(struct reset_controller_dev *rcdev,
 	for (i = 0; i < num_entries; i++) {
 		entry = &lookup[i];
 
-		if (!entry->dev_id) {
-			pr_warn("%s(): reset lookup entry has no dev_id, skipping\n",
+		if (!entry->dev_id || !entry->provider) {
+			pr_warn("%s(): reset lookup entry badly specified, skipping\n",
 				__func__);
 			continue;
 		}
 
-		entry->rcdev = rcdev;
 		list_add_tail(&entry->list, &reset_lookup_list);
 	}
 	mutex_unlock(&reset_lookup_mutex);
@@ -526,11 +523,30 @@ struct reset_control *__of_reset_control_get(struct device_node *node,
 }
 EXPORT_SYMBOL_GPL(__of_reset_control_get);
 
+static struct reset_controller_dev *
+__reset_controller_by_name(const char *name)
+{
+	struct reset_controller_dev *rcdev;
+
+	lockdep_assert_held(&reset_list_mutex);
+
+	list_for_each_entry(rcdev, &reset_controller_list, list) {
+		if (!rcdev->dev)
+			continue;
+
+		if (!strcmp(name, dev_name(rcdev->dev)))
+			return rcdev;
+	}
+
+	return NULL;
+}
+
 static struct reset_control *
 __reset_control_get_from_lookup(struct device *dev, const char *con_id,
 				bool shared, bool optional)
 {
 	const struct reset_control_lookup *lookup;
+	struct reset_controller_dev *rcdev;
 	const char *dev_id = dev_name(dev);
 	struct reset_control *rstc = NULL;
 
@@ -547,7 +563,15 @@ __reset_control_get_from_lookup(struct device *dev, const char *con_id,
 		    ((con_id && lookup->con_id) &&
 		     !strcmp(con_id, lookup->con_id))) {
 			mutex_lock(&reset_list_mutex);
-			rstc = __reset_control_get_internal(lookup->rcdev,
+			rcdev = __reset_controller_by_name(lookup->provider);
+			if (!rcdev) {
+				mutex_unlock(&reset_list_mutex);
+				mutex_unlock(&reset_lookup_mutex);
+				/* Reset provider may not be ready yet. */
+				return ERR_PTR(-EPROBE_DEFER);
+			}
+
+			rstc = __reset_control_get_internal(rcdev,
 							    lookup->index,
 							    shared);
 			mutex_unlock(&reset_list_mutex);

include/linux/reset-controller.h

@@ -30,24 +30,25 @@ struct of_phandle_args;
  * struct reset_control_lookup - represents a single lookup entry
  *
  * @list: internal list of all reset lookup entries
- * @rcdev: reset controller device controlling this reset line
+ * @provider: name of the reset controller device controlling this reset line
  * @index: ID of the reset controller in the reset controller device
  * @dev_id: name of the device associated with this reset line
  * @con_id name of the reset line (can be NULL)
  */
 struct reset_control_lookup {
 	struct list_head list;
-	struct reset_controller_dev *rcdev;
+	const char *provider;
 	unsigned int index;
 	const char *dev_id;
 	const char *con_id;
 };
 
-#define RESET_LOOKUP(_dev_id, _con_id, _index)				\
+#define RESET_LOOKUP(_provider, _index, _dev_id, _con_id)		\
 	{								\
+		.provider = _provider,					\
+		.index = _index,					\
 		.dev_id = _dev_id,					\
 		.con_id = _con_id,					\
-		.index = _index,					\
 	}
 
 /**
@@ -57,6 +58,7 @@ struct reset_control_lookup {
  * @owner: kernel module of the reset controller driver
  * @list: internal list of reset controller devices
  * @reset_control_head: head of internal list of requested reset controls
+ * @dev: corresponding driver model device struct
  * @of_node: corresponding device tree node as phandle target
  * @of_reset_n_cells: number of cells in reset line specifiers
  * @of_xlate: translation function to translate from specifier as found in the
@@ -68,6 +70,7 @@ struct reset_controller_dev {
 	struct module *owner;
 	struct list_head list;
 	struct list_head reset_control_head;
+	struct device *dev;
 	struct device_node *of_node;
 	int of_reset_n_cells;
 	int (*of_xlate)(struct reset_controller_dev *rcdev,
@@ -82,8 +85,7 @@ struct device;
 int devm_reset_controller_register(struct device *dev,
 				   struct reset_controller_dev *rcdev);
 
-void reset_controller_add_lookup(struct reset_controller_dev *rcdev,
-				 struct reset_control_lookup *lookup,
+void reset_controller_add_lookup(struct reset_control_lookup *lookup,
 				 unsigned int num_entries);
 
 #endif