[U-Boot] [PATCH v2 1/6] drivers: rtc: resolve year 2038 problem in rtc_to_tm
Alexander Graf
agraf at suse.de
Sun Jul 8 21:32:19 UTC 2018
On 07.07.18 23:39, Heinrich Schuchardt wrote:
> Our implementation of rtc_to_tm() cannot handle dates of more than
> 0x7fffffff seconds after 1970-01-01.
>
> Adopt the Linux kernel implementation.
>
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
This patch is slightly out of scope for efi-next and the other patches
are independent of it FWIW, so I'll leave it to others to review.
I'll CC Arnd though, as I'm quite sure he has a good grip on anything
2038 :)
Alex
> ---
> v2
> adopt the Linux kernel implementation
> ---
> drivers/rtc/Makefile | 1 +
> drivers/rtc/date.c | 43 ----------------------
> drivers/rtc/i2c_rtc_emul.c | 4 ++-
> drivers/rtc/rtc-lib.c | 73 ++++++++++++++++++++++++++++++++++++++
> include/rtc.h | 16 +++++++--
> 5 files changed, 90 insertions(+), 47 deletions(-)
> create mode 100644 drivers/rtc/rtc-lib.c
>
> diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
> index 09f2b08244..513e3ffc07 100644
> --- a/drivers/rtc/Makefile
> +++ b/drivers/rtc/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_DM_RTC) += rtc-uclass.o
>
> obj-$(CONFIG_RTC_AT91SAM9_RTT) += at91sam9_rtt.o
> obj-y += date.o
> +obj-y += rtc-lib.o
> obj-$(CONFIG_RTC_DAVINCI) += davinci.o
> obj-$(CONFIG_RTC_DS1302) += ds1302.o
> obj-$(CONFIG_RTC_DS1306) += ds1306.o
> diff --git a/drivers/rtc/date.c b/drivers/rtc/date.c
> index 1256ffe374..f2568cf886 100644
> --- a/drivers/rtc/date.c
> +++ b/drivers/rtc/date.c
> @@ -19,10 +19,6 @@
> #define days_in_year(a) (leapyear(a) ? 366 : 365)
> #define days_in_month(a) (month_days[(a) - 1])
>
> -static int month_days[12] = {
> - 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
> -};
> -
> static int month_offset[] = {
> 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
> };
> @@ -65,45 +61,6 @@ int rtc_calc_weekday(struct rtc_time *tm)
> return 0;
> }
>
> -int rtc_to_tm(int tim, struct rtc_time *tm)
> -{
> - register int i;
> - register long hms, day;
> -
> - day = tim / SECDAY;
> - hms = tim % SECDAY;
> -
> - /* Hours, minutes, seconds are easy */
> - tm->tm_hour = hms / 3600;
> - tm->tm_min = (hms % 3600) / 60;
> - tm->tm_sec = (hms % 3600) % 60;
> -
> - /* Number of years in days */
> - for (i = STARTOFTIME; day >= days_in_year(i); i++)
> - day -= days_in_year(i);
> - tm->tm_year = i;
> -
> - /* Number of months in days left */
> - if (leapyear(tm->tm_year))
> - days_in_month(FEBRUARY) = 29;
> - for (i = 1; day >= days_in_month(i); i++)
> - day -= days_in_month(i);
> - days_in_month(FEBRUARY) = 28;
> - tm->tm_mon = i;
> -
> - /* Days are what is left over (+1) from all that */
> - tm->tm_mday = day + 1;
> -
> - /* Zero unused fields */
> - tm->tm_yday = 0;
> - tm->tm_isdst = 0;
> -
> - /*
> - * Determine the day of week
> - */
> - return rtc_calc_weekday(tm);
> -}
> -
> /*
> * Converts Gregorian date to seconds since 1970-01-01 00:00:00.
> * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
> diff --git a/drivers/rtc/i2c_rtc_emul.c b/drivers/rtc/i2c_rtc_emul.c
> index bad61c377f..d4b33e59d6 100644
> --- a/drivers/rtc/i2c_rtc_emul.c
> +++ b/drivers/rtc/i2c_rtc_emul.c
> @@ -96,7 +96,9 @@ static int sandbox_i2c_rtc_get(struct udevice *dev, struct rtc_time *time)
> now = plat->base_time;
> }
>
> - return rtc_to_tm(now + plat->offset, time);
> + rtc_to_tm(now + plat->offset, time);
> +
> + return 0;
> }
>
> static int sandbox_i2c_rtc_set(struct udevice *dev, const struct rtc_time *time)
> diff --git a/drivers/rtc/rtc-lib.c b/drivers/rtc/rtc-lib.c
> new file mode 100644
> index 0000000000..b8a7a8b2d3
> --- /dev/null
> +++ b/drivers/rtc/rtc-lib.c
> @@ -0,0 +1,73 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * rtc and date/time utility functions
> + *
> + * Copyright (C) 2005-06 Tower Technologies
> + * Author: Alessandro Zummo <a.zummo at towertech.it>
> + *
> + * U-Boot rtc_time differs from Linux rtc_time:
> + * - The year field takes the actual value, not year - 1900.
> + * - January is month 1.
> + */
> +
> +#include <common.h>
> +#include <rtc.h>
> +#include <linux/math64.h>
> +
> +static const unsigned char rtc_days_in_month[] = {
> + 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
> +};
> +
> +#define LEAPS_THRU_END_OF(y) ((y) / 4 - (y) / 100 + (y) / 400)
> +
> +/*
> + * The number of days in the month.
> + */
> +static int rtc_month_days(unsigned int month, unsigned int year)
> +{
> + return rtc_days_in_month[month] + (is_leap_year(year) && month == 1);
> +}
> +
> +/*
> + * rtc_to_tm - Converts u64 to rtc_time.
> + * Convert seconds since 01-01-1970 00:00:00 to Gregorian date.
> + */
> +void rtc_to_tm(u64 time, struct rtc_time *tm)
> +{
> + unsigned int month, year, secs, days;
> +
> + days = div_u64_rem(time, 86400, &secs);
> +
> + /* day of the week, 1970-01-01 was a Thursday */
> + tm->tm_wday = (days + 4) % 7;
> +
> + year = 1970 + days / 365;
> + days -= (year - 1970) * 365
> + + LEAPS_THRU_END_OF(year - 1)
> + - LEAPS_THRU_END_OF(1970 - 1);
> + while (days < 0) {
> + year -= 1;
> + days += 365 + is_leap_year(year);
> + }
> + tm->tm_year = year; /* Not year - 1900 */
> + tm->tm_yday = days + 1;
> +
> + for (month = 0; month < 11; month++) {
> + int newdays;
> +
> + newdays = days - rtc_month_days(month, year);
> + if (newdays < 0)
> + break;
> + days = newdays;
> + }
> + tm->tm_mon = month + 1; /* January = 1 */
> + tm->tm_mday = days + 1;
> +
> + tm->tm_hour = secs / 3600;
> + secs -= tm->tm_hour * 3600;
> + tm->tm_min = secs / 60;
> + tm->tm_sec = secs - tm->tm_min * 60;
> +
> + /* Zero unused fields */
> + tm->tm_isdst = 0;
> +}
> diff --git a/include/rtc.h b/include/rtc.h
> index 746624d799..0d964d56d5 100644
> --- a/include/rtc.h
> +++ b/include/rtc.h
> @@ -208,7 +208,18 @@ void rtc_write32(int reg, u32 value);
> * rtc_init() - Set up the real time clock ready for use
> */
> void rtc_init(void);
> -#endif
> +#endif /* CONFIG_DM_RTC */
> +
> +/**
> + * is_leap_year - Check if year is a leap year
> + *
> + * @year Year
> + * @return 1 if leap year
> + */
> +static inline bool is_leap_year(unsigned int year)
> +{
> + return (!(year % 4) && (year % 100)) || !(year % 400);
> +}
>
> /**
> * rtc_calc_weekday() - Work out the weekday from a time
> @@ -231,9 +242,8 @@ int rtc_calc_weekday(struct rtc_time *time);
> *
> * @time_t: Number of seconds since 1970-01-01 00:00:00
> * @time: Place to put the broken-out time
> - * @return 0 if OK, -EINVAL if the weekday could not be determined
> */
> -int rtc_to_tm(int time_t, struct rtc_time *time);
> +void rtc_to_tm(u64 time_t, struct rtc_time *time);
>
> /**
> * rtc_mktime() - Convert a broken-out time into a time_t value
>
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