[patch 2.6.28-rc7] regulator: catch some registration errors

[David Brownell <david-b@pacbell.net>]

From: David Brownell <dbrownell@users.sourceforge.net>

Prevent registration of duplicate "struct regulator" names.
They'd be unavailable, and clearly indicate something wrong.

Also make sure the consumer device is provided.  It's nonsensical
to omit these, and not a documented part of the interface.  Since
no code in mainline does such stuff, this is just anti-oops medicine.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
 drivers/regulator/core.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -772,9 +772,23 @@ static int set_consumer_device_supply(st
 {
 	struct regulator_map *node;
 
-	if (supply == NULL)
+	if (supply == NULL || !consumer_dev)
 		return -EINVAL;
 
+	list_for_each_entry(node, &regulator_map_list, list) {
+		if (consumer_dev != node->dev)
+			continue;
+		if (strcmp(node->supply, supply) != 0)
+			continue;
+
+		dev_dbg(consumer_dev, "%s/%s is '%s' supply; fail %s/%s\n",
+				dev_name(&node->regulator->dev),
+				node->regulator->desc->name,
+				supply,
+				dev_name(&rdev->dev), rdev->desc->name);
+		return -EBUSY;
+	}
+
 	node = kmalloc(sizeof(struct regulator_map), GFP_KERNEL);
 	if (node == NULL)
 		return -ENOMEM;