rtc/hctosys: only claim the RTC provided the system time if it did

Without this patch /sys/class/rtc/$CONFIG_RTC_HCTOSYS_DEVICE/hctosys
contains a 1 (meaning "This rtc was used to initialize the system clock")
even if reading the time at bootup failed.

Moreover change error handling in rtc_hctosys() to use goto and so reduce
the indention level.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Paul Gortmaker <p_gortmaker@yahoo.com>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/hctosys.c

@@ -22,25 +22,37 @@
  * the best guess is to add 0.5s.
  */
 
+int rtc_hctosys_ret = -ENODEV;
+
 static int __init rtc_hctosys(void)
 {
-	int err;
+	int err = -ENODEV;
 	struct rtc_time tm;
+	struct timespec tv = {
+		.tv_nsec = NSEC_PER_SEC >> 1,
+	};
 	struct rtc_device *rtc = rtc_class_open(CONFIG_RTC_HCTOSYS_DEVICE);
 
 	if (rtc == NULL) {
-		printk("%s: unable to open rtc device (%s)\n",
+		pr_err("%s: unable to open rtc device (%s)\n",
 			__FILE__, CONFIG_RTC_HCTOSYS_DEVICE);
-		return -ENODEV;
+		goto err_open;
 	}
 
 	err = rtc_read_time(rtc, &tm);
-	if (err == 0) {
-		err = rtc_valid_tm(&tm);
-		if (err == 0) {
-			struct timespec tv;
+	if (err) {
+		dev_err(rtc->dev.parent,
+			"hctosys: unable to read the hardware clock\n");
+		goto err_read;
 
-			tv.tv_nsec = NSEC_PER_SEC >> 1;
+	}
+
+	err = rtc_valid_tm(&tm);
+	if (err) {
+		dev_err(rtc->dev.parent,
+			"hctosys: invalid date/time\n");
+		goto err_invalid;
+	}
 
 	rtc_tm_to_time(&tm, &tv.tv_sec);
 
@@ -52,18 +64,15 @@ static int __init rtc_hctosys(void)
 		tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
 		tm.tm_hour, tm.tm_min, tm.tm_sec,
 		(unsigned int) tv.tv_sec);
-		}
-		else
-			dev_err(rtc->dev.parent,
-				"hctosys: invalid date/time\n");
-	}
-	else
-		dev_err(rtc->dev.parent,
-			"hctosys: unable to read the hardware clock\n");
 
+err_invalid:
+err_read:
 	rtc_class_close(rtc);
 
-	return 0;
+err_open:
+	rtc_hctosys_ret = err;
+
+	return err;
 }
 
 late_initcall(rtc_hctosys);

drivers/rtc/rtc-sysfs.c

@@ -107,7 +107,8 @@ rtc_sysfs_show_hctosys(struct device *dev, struct device_attribute *attr,
 		char *buf)
 {
 #ifdef CONFIG_RTC_HCTOSYS_DEVICE
-	if (strcmp(dev_name(&to_rtc_device(dev)->dev),
+	if (rtc_hctosys_ret == 0 &&
+			strcmp(dev_name(&to_rtc_device(dev)->dev),
 				CONFIG_RTC_HCTOSYS_DEVICE) == 0)
 		return sprintf(buf, "1\n");
 	else

include/linux/rtc.h

@@ -238,6 +238,12 @@ static inline bool is_leap_year(unsigned int year)
 	return (!(year % 4) && (year % 100)) || !(year % 400);
 }
 
+#ifdef CONFIG_RTC_HCTOSYS
+extern int rtc_hctosys_ret;
+#else
+#define rtc_hctosys_ret -ENODEV
+#endif
+
 #endif /* __KERNEL__ */
 
 #endif /* _LINUX_RTC_H_ */