rtc: sysfs: facilitate attribute add to rtc device

This patches addresses following problem:
rtc_allocate_device
devm_device_add_group  <-- kernel oops / null pointer, because
			sysfs entry does not yet exist
rtc_register_device
rc = devm_device_add_group
if (rc)
	return rc;     <-- forbidden to return error code
			after device register

This patch adds rtc_add_group(s) functions.
The functions store the sum of attribute groups as device resource.

Signed-off-by: Denis Osterland <Denis.Osterland@diehl.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-core.h b/drivers/rtc/rtc-core.h
index 0abf989..ccc17a2 100644 (file)
--- a/drivers/rtc/rtc-core.h
+++ b/drivers/rtc/rtc-core.h
@@ -40,9 +40,23 @@ static inline void rtc_proc_del_device(struct rtc_device *rtc)
 
 #ifdef CONFIG_RTC_INTF_SYSFS
 const struct attribute_group **rtc_get_dev_attribute_groups(void);
+int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp);
+int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps);
 #else
 static inline const struct attribute_group **rtc_get_dev_attribute_groups(void)
 {
        return NULL;
 }
+
+static inline
+int rtc_add_group(struct rtc_device *rtc, const struct attribute_group *grp)
+{
+       return 0;
+}
+
+static inline
+int rtc_add_groups(struct rtc_device *rtc, const struct attribute_group **grps)
+{
+       return 0;
+}
 #endif

diff --git a/drivers/rtc/rtc-sysfs.c b/drivers/rtc/rtc-sysfs.c
index 454da38..f1ff30a 100644 (file)
--- 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);