rtc: sun6i: Add support for broken-down alarm registers

Newer versions of the Allwinner RTC, for instance as found in the H616
SoC, not only store the current day as a linear number, but also change
the way the alarm is handled: There are now two registers, that
explicitly store the wakeup time, in the same format as the current
time.

Add support for that variant by writing the requested wakeup time
directly into the registers, instead of programming the seconds left, as
the old SoCs required.

Reviewed by: Jernej Skrabec <jernej.skrabec@gmail.com>

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220211122643.1343315-6-andre.przywara@arm.com

diff --git a/drivers/rtc/rtc-sun6i.c b/drivers/rtc/rtc-sun6i.c
index e1245ee4d99b42f039c8fafafb2f3cdd14a1e719..448e0e14a9ffd5371a88c9a18b7a5090f050c8db 100644 (file)
--- a/drivers/rtc/rtc-sun6i.c
+++ b/drivers/rtc/rtc-sun6i.c
@@ -48,7 +48,8 @@
 
 /* Alarm 0 (counter) */
 #define SUN6I_ALRM_COUNTER                     0x0020
-#define SUN6I_ALRM_CUR_VAL                     0x0024
+/* This holds the remaining alarm seconds on older SoCs (current value) */
+#define SUN6I_ALRM_COUNTER_HMS                 0x0024
 #define SUN6I_ALRM_EN                          0x0028
 #define SUN6I_ALRM_EN_CNT_EN                   BIT(0)
 #define SUN6I_ALRM_IRQ_EN                      0x002c
@@ -523,32 +524,54 @@ static int sun6i_rtc_setalarm(struct device *dev, struct rtc_wkalrm *wkalrm)
        struct sun6i_rtc_dev *chip = dev_get_drvdata(dev);
        struct rtc_time *alrm_tm = &wkalrm->time;
        struct rtc_time tm_now;
-       time64_t time_now, time_set;
+       time64_t time_set;
+       u32 counter_val, counter_val_hms;
        int ret;
 
-       ret = sun6i_rtc_gettime(dev, &tm_now);
-       if (ret < 0) {
-               dev_err(dev, "Error in getting time\n");
-               return -EINVAL;
-       }
-
        time_set = rtc_tm_to_time64(alrm_tm);
-       time_now = rtc_tm_to_time64(&tm_now);
-       if (time_set <= time_now) {
-               dev_err(dev, "Date to set in the past\n");
-               return -EINVAL;
-       }
 
-       if ((time_set - time_now) > U32_MAX) {
-               dev_err(dev, "Date too far in the future\n");
-               return -EINVAL;
+       if (chip->flags & RTC_LINEAR_DAY) {
+               /*
+                * The alarm registers hold the actual alarm time, encoded
+                * in the same way (linear day + HMS) as the current time.
+                */
+               counter_val_hms = SUN6I_TIME_SET_SEC_VALUE(alrm_tm->tm_sec)  |
+                                 SUN6I_TIME_SET_MIN_VALUE(alrm_tm->tm_min)  |
+                                 SUN6I_TIME_SET_HOUR_VALUE(alrm_tm->tm_hour);
+               /* The division will cut off the H:M:S part of alrm_tm. */
+               counter_val = div_u64(rtc_tm_to_time64(alrm_tm), SECS_PER_DAY);
+       } else {
+               /* The alarm register holds the number of seconds left. */
+               time64_t time_now;
+
+               ret = sun6i_rtc_gettime(dev, &tm_now);
+               if (ret < 0) {
+                       dev_err(dev, "Error in getting time\n");
+                       return -EINVAL;
+               }
+
+               time_now = rtc_tm_to_time64(&tm_now);
+               if (time_set <= time_now) {
+                       dev_err(dev, "Date to set in the past\n");
+                       return -EINVAL;
+               }
+               if ((time_set - time_now) > U32_MAX) {
+                       dev_err(dev, "Date too far in the future\n");
+                       return -EINVAL;
+               }
+
+               counter_val = time_set - time_now;
        }
 
        sun6i_rtc_setaie(0, chip);
        writel(0, chip->base + SUN6I_ALRM_COUNTER);
+       if (chip->flags & RTC_LINEAR_DAY)
+               writel(0, chip->base + SUN6I_ALRM_COUNTER_HMS);
        usleep_range(100, 300);
 
-       writel(time_set - time_now, chip->base + SUN6I_ALRM_COUNTER);
+       writel(counter_val, chip->base + SUN6I_ALRM_COUNTER);
+       if (chip->flags & RTC_LINEAR_DAY)
+               writel(counter_val_hms, chip->base + SUN6I_ALRM_COUNTER_HMS);
        chip->alarm = time_set;
 
        sun6i_rtc_setaie(wkalrm->enabled, chip);