1 files changed, 20 insertions, 4 deletions

diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index 02426812bebc..589351ef75d0 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -14,6 +14,7 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/rtc.h>
 #include <linux/kdev_t.h>
 #include <linux/idr.h>
@@ -157,12 +158,27 @@ struct rtc_device *rtc_device_register(const char *name, struct device *dev,
 {
         struct rtc_device *rtc;
         struct rtc_wkalrm alrm;
-        int id, err;
+        int of_id = -1, id = -1, err;
+
+        if (dev->of_node)
+                of_id = of_alias_get_id(dev->of_node, "rtc");
+        else if (dev->parent && dev->parent->of_node)
+                of_id = of_alias_get_id(dev->parent->of_node, "rtc");
+
+        if (of_id >= 0) {
+                id = ida_simple_get(&rtc_ida, of_id, of_id + 1,
+                                    GFP_KERNEL);
+                if (id < 0)
+                        dev_warn(dev, "/aliases ID %d not available\n",
+                                    of_id);
+        }
 
-        id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
         if (id < 0) {
-                err = id;
-                goto exit;
+                id = ida_simple_get(&rtc_ida, 0, 0, GFP_KERNEL);
+                if (id < 0) {
+                        err = id;
+                        goto exit;
+                }
         }
 
         rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);