rtc: ab8500: let the core handle range

Let the core handle offsetting and windowing the RTC range.
The RTC has a 24 bit counter for minutes plus a seconds counter.
Keep the epoch at the beginning of 2000.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

1 files changed, 4 insertions, 49 deletions

diff --git a/drivers/rtc/rtc-ab8500.c b/drivers/rtc/rtc-ab8500.c
index e97015e5c63e..2e2671b84ab0 100644
--- a/drivers/rtc/rtc-ab8500.c
+++ b/drivers/rtc/rtc-ab8500.c
@@ -46,7 +46,6 @@
 #define RTC_STATUS_DATA                 0x01
 
 #define COUNTS_PER_SEC                  (0xF000 / 60)
-#define AB8500_RTC_EPOCH                2000
 
 static const u8 ab8500_rtc_time_regs[] = {
         AB8500_RTC_WATCH_TMIN_HI_REG, AB8500_RTC_WATCH_TMIN_MID_REG,
@@ -59,23 +58,6 @@ static const u8 ab8500_rtc_alarm_regs[] = {
         AB8500_RTC_ALRM_MIN_LOW_REG
 };
 
-/* Calculate the seconds from 1970 to 01-01-2000 00:00:00 */
-static unsigned long get_elapsed_seconds(int year)
-{
-        unsigned long secs;
-        struct rtc_time tm = {
-                .tm_year = year - 1900,
-                .tm_mday = 1,
-        };
-
-        /*
-         * This function calculates secs from 1970 and not from
-         * 1900, even if we supply the offset from year 1900.
-         */
-        rtc_tm_to_time(&tm, &secs);
-        return secs;
-}
-
 static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
 {
         unsigned long timeout = jiffies + HZ;
@@ -118,9 +100,6 @@ static int ab8500_rtc_read_time(struct device *dev, struct rtc_time *tm)
         secs =  secs / COUNTS_PER_SEC;
         secs =  secs + (mins * 60);
 
-        /* Add back the initially subtracted number of seconds */
-        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
-
         rtc_time_to_tm(secs, tm);
         return 0;
 }
@@ -131,21 +110,8 @@ static int ab8500_rtc_set_time(struct device *dev, struct rtc_time *tm)
         unsigned char buf[ARRAY_SIZE(ab8500_rtc_time_regs)];
         unsigned long no_secs, no_mins, secs = 0;
 
-        if (tm->tm_year < (AB8500_RTC_EPOCH - 1900)) {
-                dev_dbg(dev, "year should be equal to or greater than %d\n",
-                                AB8500_RTC_EPOCH);
-                return -EINVAL;
-        }
-
-        /* Get the number of seconds since 1970 */
         rtc_tm_to_time(tm, &secs);
 
-        /*
-         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
-         * we only have a small counter in the RTC.
-         */
-        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
-
         no_mins = secs / 60;
 
         no_secs = secs % 60;
@@ -202,9 +168,6 @@ static int ab8500_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
         mins = (buf[0] << 16) | (buf[1] << 8) | (buf[2]);
         secs = mins * 60;
 
-        /* Add back the initially subtracted number of seconds */
-        secs += get_elapsed_seconds(AB8500_RTC_EPOCH);
-
         rtc_time_to_tm(secs, &alarm->time);
 
         return rtc_valid_tm(&alarm->time);
@@ -224,12 +187,6 @@ static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
         unsigned long mins, secs = 0, cursec = 0;
         struct rtc_time curtm;
 
-        if (alarm->time.tm_year < (AB8500_RTC_EPOCH - 1900)) {
-                dev_dbg(dev, "year should be equal to or greater than %d\n",
-                                AB8500_RTC_EPOCH);
-                return -EINVAL;
-        }
-
         /* Get the number of seconds since 1970 */
         rtc_tm_to_time(&alarm->time, &secs);
 
@@ -245,12 +202,6 @@ static int ab8500_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
                 return -EINVAL;
         }
 
-        /*
-         * Convert it to the number of seconds since 01-01-2000 00:00:00, since
-         * we only have a small counter in the RTC.
-         */
-        secs -= get_elapsed_seconds(AB8500_RTC_EPOCH);
-
         mins = secs / 60;
 
         buf[2] = mins & 0xFF;
@@ -445,6 +396,10 @@ static int ab8500_rtc_probe(struct platform_device *pdev)
 
         rtc->uie_unsupported = 1;
 
+        rtc->range_max = (1ULL << 24) * 60 - 1; // 24-bit minutes + 59 secs
+        rtc->start_secs = RTC_TIMESTAMP_BEGIN_2000;
+        rtc->set_start_time = true;
+
         err = rtc_add_group(rtc, &ab8500_rtc_sysfs_files);
         if (err)
                 return err;