Create a unique cdev number for on demand devices

For disk like devices attached to MCI, ATA or USB it depends on the order they
will be recognized. So an unique number for all disk like devices is required.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 14 insertions, 0 deletions

diff --git a/fs/devfs-core.c b/fs/devfs-core.c
index 519e18e6b7..9bc3126d6b 100644
--- a/fs/devfs-core.c
+++ b/fs/devfs-core.c
@@ -40,6 +40,20 @@ struct cdev *cdev_by_name(const char *filename)
 	return NULL;
 }
 
+int cdev_find_free_index(const char *basename)
+{
+	int i;
+	char fname[100];
+
+	for (i = 0; i < 1000; i++) {
+		snprintf(fname, sizeof(fname), "%s%d", basename, i);
+		if (cdev_by_name(fname) == NULL)
+			return i;
+	}
+
+	return -EBUSY;	/* all indexes are used */
+}
+
 struct cdev *cdev_open(const char *name, unsigned long flags)
 {
 	struct cdev *cdev = cdev_by_name(name);