1 files changed, 43 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 454da38c6012..f1ff30ade534 100644
--- a/drivers/rtc/rtc-sysfs.c
+++ b/drivers/rtc/rtc-sysfs.c
@@ -317,3 +317,46 @@ const struct attribute_group **rtc_get_dev_attribute_groups(void)
 {
         return rtc_attr_groups;
 }
+
+int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps)
+{
+        size_t old_cnt = 0, add_cnt = 0, new_cnt;
+        const struct attribute_group **groups, **old;
+
+        if (rtc->registered)
+                return -EINVAL;
+        if (!grps)
+                return -EINVAL;
+
+        groups = rtc->dev.groups;
+        if (groups)
+                for (; *groups; groups++)
+                        old_cnt++;
+
+        for (groups = grps; *groups; groups++)
+                add_cnt++;
+
+        new_cnt = old_cnt + add_cnt + 1;
+        groups = devm_kcalloc(&rtc->dev, new_cnt, sizeof(*groups), GFP_KERNEL);
+        if (IS_ERR_OR_NULL(groups))
+                return PTR_ERR(groups);
+        memcpy(groups, rtc->dev.groups, old_cnt * sizeof(*groups));
+        memcpy(groups + old_cnt, grps, add_cnt * sizeof(*groups));
+        groups[old_cnt + add_cnt] = NULL;
+
+        old = rtc->dev.groups;
+        rtc->dev.groups = groups;
+        if (old && old != rtc_attr_groups)
+                devm_kfree(&rtc->dev, old);
+
+        return 0;
+}
+EXPORT_SYMBOL(rtc_add_groups);
+
+int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
+{
+        const struct attribute_group *groups[] = { grp, NULL };
+
+        return rtc_add_groups(rtc, groups);
+}
+EXPORT_SYMBOL(rtc_add_group);