From f076ef44a44d02ed91543f820c14c2c7dff53716 Mon Sep 17 00:00:00 2001 From: Julius Werner Date: Tue, 15 Dec 2015 15:02:49 -0800 Subject: rtc: rk808: Compensate for Rockchip calendar deviation on November 31st In A.D. 1582 Pope Gregory XIII found that the existing Julian calendar insufficiently represented reality, and changed the rules about calculating leap years to account for this. Similarly, in A.D. 2013 Rockchip hardware engineers found that the new Gregorian calendar still contained flaws, and that the month of November should be counted up to 31 days instead. Unfortunately it takes a long time for calendar changes to gain widespread adoption, and just like more than 300 years went by before the last Protestant nation implemented Greg's proposal, we will have to wait a while until all religions and operating system kernels acknowledge the inherent advantages of the Rockchip system. Until then we need to translate dates read from (and written to) Rockchip hardware back to the Gregorian format. This patch works by defining Jan 1st, 2016 as the arbitrary anchor date on which Rockchip and Gregorian calendars are in sync. From that we can translate arbitrary later dates back and forth by counting the number of November/December transitons since the anchor date to determine the offset between the calendars. We choose this method (rather than trying to regularly "correct" the date stored in hardware) since it's the only way to ensure perfect time-keeping even if the system may be shut down for an unknown number of years. The drawback is that other software reading the same hardware (e.g. mainboard firmware) must use the same translation convention (including the same anchor date) to be able to read and write correct timestamps from/to the RTC. Signed-off-by: Julius Werner Reviewed-by: Douglas Anderson Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-rk808.c | 48 ++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 44 insertions(+), 4 deletions(-) (limited to 'drivers') diff --git a/drivers/rtc/rtc-rk808.c b/drivers/rtc/rtc-rk808.c index 91ca0bc1b484..35c9aada07c8 100644 --- a/drivers/rtc/rtc-rk808.c +++ b/drivers/rtc/rtc-rk808.c @@ -56,6 +56,42 @@ struct rk808_rtc { int irq; }; +/* + * The Rockchip calendar used by the RK808 counts November with 31 days. We use + * these translation functions to convert its dates to/from the Gregorian + * calendar used by the rest of the world. We arbitrarily define Jan 1st, 2016 + * as the day when both calendars were in sync, and treat all other dates + * relative to that. + * NOTE: Other system software (e.g. firmware) that reads the same hardware must + * implement this exact same conversion algorithm, with the same anchor date. + */ +static time64_t nov2dec_transitions(struct rtc_time *tm) +{ + return (tm->tm_year + 1900) - 2016 + (tm->tm_mon + 1 > 11 ? 1 : 0); +} + +static void rockchip_to_gregorian(struct rtc_time *tm) +{ + /* If it's Nov 31st, rtc_tm_to_time64() will count that like Dec 1st */ + time64_t time = rtc_tm_to_time64(tm); + rtc_time64_to_tm(time + nov2dec_transitions(tm) * 86400, tm); +} + +static void gregorian_to_rockchip(struct rtc_time *tm) +{ + time64_t extra_days = nov2dec_transitions(tm); + time64_t time = rtc_tm_to_time64(tm); + rtc_time64_to_tm(time - extra_days * 86400, tm); + + /* Compensate if we went back over Nov 31st (will work up to 2381) */ + if (nov2dec_transitions(tm) < extra_days) { + if (tm->tm_mon + 1 == 11) + tm->tm_mday++; /* This may result in 31! */ + else + rtc_time64_to_tm(time - (extra_days - 1) * 86400, tm); + } +} + /* Read current time and date in RTC */ static int rk808_rtc_readtime(struct device *dev, struct rtc_time *tm) { @@ -101,9 +137,10 @@ static int rk808_rtc_readtime(struct device *dev, struct rtc_time *tm) tm->tm_mon = (bcd2bin(rtc_data[4] & MONTHS_REG_MSK)) - 1; tm->tm_year = (bcd2bin(rtc_data[5] & YEARS_REG_MSK)) + 100; tm->tm_wday = bcd2bin(rtc_data[6] & WEEKS_REG_MSK); + rockchip_to_gregorian(tm); dev_dbg(dev, "RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n", 1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday, - tm->tm_wday, tm->tm_hour , tm->tm_min, tm->tm_sec); + tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec); return ret; } @@ -116,6 +153,10 @@ static int rk808_rtc_set_time(struct device *dev, struct rtc_time *tm) u8 rtc_data[NUM_TIME_REGS]; int ret; + dev_dbg(dev, "set RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n", + 1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday, + tm->tm_wday, tm->tm_hour, tm->tm_min, tm->tm_sec); + gregorian_to_rockchip(tm); rtc_data[0] = bin2bcd(tm->tm_sec); rtc_data[1] = bin2bcd(tm->tm_min); rtc_data[2] = bin2bcd(tm->tm_hour); @@ -123,9 +164,6 @@ static int rk808_rtc_set_time(struct device *dev, struct rtc_time *tm) rtc_data[4] = bin2bcd(tm->tm_mon + 1); rtc_data[5] = bin2bcd(tm->tm_year - 100); rtc_data[6] = bin2bcd(tm->tm_wday); - dev_dbg(dev, "set RTC date/time %4d-%02d-%02d(%d) %02d:%02d:%02d\n", - 1900 + tm->tm_year, tm->tm_mon + 1, tm->tm_mday, - tm->tm_wday, tm->tm_hour , tm->tm_min, tm->tm_sec); /* Stop RTC while updating the RTC registers */ ret = regmap_update_bits(rk808->regmap, RK808_RTC_CTRL_REG, @@ -170,6 +208,7 @@ static int rk808_rtc_readalarm(struct device *dev, struct rtc_wkalrm *alrm) alrm->time.tm_mday = bcd2bin(alrm_data[3] & DAYS_REG_MSK); alrm->time.tm_mon = (bcd2bin(alrm_data[4] & MONTHS_REG_MSK)) - 1; alrm->time.tm_year = (bcd2bin(alrm_data[5] & YEARS_REG_MSK)) + 100; + rockchip_to_gregorian(&alrm->time); ret = regmap_read(rk808->regmap, RK808_RTC_INT_REG, &int_reg); if (ret) { @@ -227,6 +266,7 @@ static int rk808_rtc_setalarm(struct device *dev, struct rtc_wkalrm *alrm) alrm->time.tm_mday, alrm->time.tm_wday, alrm->time.tm_hour, alrm->time.tm_min, alrm->time.tm_sec); + gregorian_to_rockchip(&alrm->time); alrm_data[0] = bin2bcd(alrm->time.tm_sec); alrm_data[1] = bin2bcd(alrm->time.tm_min); alrm_data[2] = bin2bcd(alrm->time.tm_hour); -- cgit v1.2.3-59-g8ed1b From 77535acedc26627f16a1a39c1471f942689fe11e Mon Sep 17 00:00:00 2001 From: Steve Twiss Date: Tue, 8 Dec 2015 16:28:39 +0000 Subject: rtc: da9063: fix access ordering error during RTC interrupt at system power on This fix alters the ordering of the IRQ and device registrations in the RTC driver probe function. This change will apply to the RTC driver that supports both DA9063 and DA9062 PMICs. A problem could occur with the existing RTC driver if: A system is started from a cold boot using the PMIC RTC IRQ to initiate a power on operation. For instance, if an RTC alarm is used to start a platform from power off. The existing driver IRQ is requested before the device has been properly registered. i.e. ret = devm_request_threaded_irq() comes before rtc->rtc_dev = devm_rtc_device_register(); In this case, the interrupt can be called before the device has been registered and the handler can be called immediately. The IRQ handler da9063_alarm_event() contains the function call rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF); which in turn tries to access the unavailable rtc->rtc_dev. The fix is to reorder the functions inside the RTC probe. The IRQ is requested after the RTC device resource has been registered so that get_irq_byname is the last thing to happen. Signed-off-by: Steve Twiss Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-da9063.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) (limited to 'drivers') diff --git a/drivers/rtc/rtc-da9063.c b/drivers/rtc/rtc-da9063.c index 284b587da65c..d6c853bbfa9f 100644 --- a/drivers/rtc/rtc-da9063.c +++ b/drivers/rtc/rtc-da9063.c @@ -483,24 +483,23 @@ static int da9063_rtc_probe(struct platform_device *pdev) platform_set_drvdata(pdev, rtc); + rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, DA9063_DRVNAME_RTC, + &da9063_rtc_ops, THIS_MODULE); + if (IS_ERR(rtc->rtc_dev)) + return PTR_ERR(rtc->rtc_dev); + + da9063_data_to_tm(data, &rtc->alarm_time, rtc); + rtc->rtc_sync = false; + irq_alarm = platform_get_irq_byname(pdev, "ALARM"); ret = devm_request_threaded_irq(&pdev->dev, irq_alarm, NULL, da9063_alarm_event, IRQF_TRIGGER_LOW | IRQF_ONESHOT, "ALARM", rtc); - if (ret) { + if (ret) dev_err(&pdev->dev, "Failed to request ALARM IRQ %d: %d\n", irq_alarm, ret); - return ret; - } - - rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, DA9063_DRVNAME_RTC, - &da9063_rtc_ops, THIS_MODULE); - if (IS_ERR(rtc->rtc_dev)) - return PTR_ERR(rtc->rtc_dev); - da9063_data_to_tm(data, &rtc->alarm_time, rtc); - rtc->rtc_sync = false; return ret; } -- cgit v1.2.3-59-g8ed1b