rtc: mc13xxx: make rtc_read_time() more readable

Remove unnecessary locks when reading the time and make the read
operation until the values of day matched between reading the seconds,
it will make the mc13xxx_rtc_read_time() procedure more readable.
Additionally, patch introduced a "seconds in a day" definition.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Sascha Hauer <kernel@pengutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 36 deletions

diff --git a/drivers/rtc/rtc-mc13xxx.c b/drivers/rtc/rtc-mc13xxx.c
index 7b39852eb542..9b1a77eb91a9 100644
--- a/drivers/rtc/rtc-mc13xxx.c
+++ b/drivers/rtc/rtc-mc13xxx.c
@@ -23,6 +23,8 @@
 #define MC13XXX_RTCDAY  22
 #define MC13XXX_RTCDAYA 23
 
+#define SEC_PER_DAY     (24 * 60 * 60)
+
 struct mc13xxx_rtc {
         struct rtc_device *rtc;
         struct mc13xxx *mc13xxx;
@@ -61,42 +63,27 @@ static int mc13xxx_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
         struct mc13xxx_rtc *priv = dev_get_drvdata(dev);
         unsigned int seconds, days1, days2;
-        unsigned long s1970;
-        int ret;
 
         if (!priv->valid)
                 return -ENODATA;
 
-        mc13xxx_lock(priv->mc13xxx);
+        do {
+                int ret;
 
-        ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCDAY, &days1);
-        if (unlikely(ret))
-                goto out;
-
-        ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCTOD, &seconds);
-        if (unlikely(ret))
-                goto out;
-
-        ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCDAY, &days2);
-out:
-        mc13xxx_unlock(priv->mc13xxx);
-
-        if (ret)
-                return ret;
-
-        if (days2 == days1 + 1) {
-                if (seconds >= 86400 / 2)
-                        days2 = days1;
-                else
-                        days1 = days2;
-        }
+                ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCDAY, &days1);
+                if (ret)
+                        return ret;
 
-        if (days1 != days2)
-                return -EIO;
+                ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCTOD, &seconds);
+                if (ret)
+                        return ret;
 
-        s1970 = days1 * 86400 + seconds;
+                ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCDAY, &days2);
+                if (ret)
+                        return ret;
+        } while (days1 != days2);
 
-        rtc_time_to_tm(s1970, tm);
+        rtc_time_to_tm(days1 * SEC_PER_DAY + seconds, tm);
 
         return rtc_valid_tm(tm);
 }
@@ -108,8 +95,8 @@ static int mc13xxx_rtc_set_mmss(struct device *dev, unsigned long secs)
         unsigned int alarmseconds;
         int ret;
 
-        seconds = secs % 86400;
-        days = secs / 86400;
+        seconds = secs % SEC_PER_DAY;
+        days = secs / SEC_PER_DAY;
 
         mc13xxx_lock(priv->mc13xxx);
 
@@ -121,7 +108,7 @@ static int mc13xxx_rtc_set_mmss(struct device *dev, unsigned long secs)
         if (unlikely(ret))
                 goto out;
 
-        if (alarmseconds < 86400) {
+        if (alarmseconds < SEC_PER_DAY) {
                 ret = mc13xxx_reg_write(priv->mc13xxx,
                                 MC13XXX_RTCTODA, 0x1ffff);
                 if (unlikely(ret))
@@ -145,7 +132,7 @@ static int mc13xxx_rtc_set_mmss(struct device *dev, unsigned long secs)
                 goto out;
 
         /* restore alarm */
-        if (alarmseconds < 86400) {
+        if (alarmseconds < SEC_PER_DAY) {
                 ret = mc13xxx_reg_write(priv->mc13xxx,
                                 MC13XXX_RTCTODA, alarmseconds);
                 if (unlikely(ret))
@@ -181,7 +168,7 @@ static int mc13xxx_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
         ret = mc13xxx_reg_read(priv->mc13xxx, MC13XXX_RTCTODA, &seconds);
         if (unlikely(ret))
                 goto out;
-        if (seconds >= 86400) {
+        if (seconds >= SEC_PER_DAY) {
                 ret = -ENODATA;
                 goto out;
         }
@@ -202,7 +189,7 @@ out:
         alarm->enabled = enabled;
         alarm->pending = pending;
 
-        s1970 = days * 86400 + seconds;
+        s1970 = days * SEC_PER_DAY + seconds;
 
         rtc_time_to_tm(s1970, &alarm->time);
         dev_dbg(dev, "%s: %lu\n", __func__, s1970);
@@ -240,8 +227,8 @@ static int mc13xxx_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
         if (unlikely(ret))
                 goto out;
 
-        seconds = s1970 % 86400;
-        days = s1970 / 86400;
+        seconds = s1970 % SEC_PER_DAY;
+        days = s1970 / SEC_PER_DAY;
 
         ret = mc13xxx_reg_write(priv->mc13xxx, MC13XXX_RTCDAYA, days);
         if (unlikely(ret))