Up to now the emulated RTC is initialized using the U-Boot build time.
With this patch the environment variable 'rtc_emul_epoch' can be used to provide a better initial time. The variable is a decimal string with the number of seconds since 1970-01-01. Here is an example where the RTC had not been probed yet:
=> setenv rtc_emul_epoch 1610109000 => date Date: 2021-01-08 (Friday) Time: 12:30:00
If the variable does not exist, the U-Boot build time is used as fallback.
The environment variable may be set when shutting down the operating system if the U-Boot environment is exposed to the OS (cf. ENV_IS_IN_FAT and ENV_IS_IN_EXT4).
Suggested-by: Pablo Sebastián Greco pgreco@centosproject.org Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de --- drivers/rtc/Kconfig | 13 ++++++++----- drivers/rtc/emul_rtc.c | 16 +++++++++++++--- 2 files changed, 21 insertions(+), 8 deletions(-)
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index d06d272e14..cad667a404 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -68,11 +68,14 @@ config RTC_EMULATION depends on DM_RTC help On a board without hardware clock this software real time clock can be - used. The build time is used to initialize the RTC. So you will have - to adjust the time either manually using the 'date' command or use - the 'sntp' to update the RTC with the time from a network time server. - See CONFIG_CMD_SNTP and CONFIG_BOOTP_NTPSERVER. The RTC time is - advanced according to CPU ticks. + used. The initial time may be provided via the environment variable + 'rtc_emul_epoch' as a decimal string indicating seconds since + 1970-01-01. If the environment variable is missing, the build time is + used to initialize the RTC. The time can be adjusted manually via the + 'date' command or the 'sntp' command can be used to update the RTC + with the time from a network time server. See CONFIG_CMD_SNTP and + CONFIG_BOOTP_NTPSERVER. The RTC time is advanced according to CPU + ticks.
config RTC_ISL1208 bool "Enable ISL1208 driver" diff --git a/drivers/rtc/emul_rtc.c b/drivers/rtc/emul_rtc.c index 209b4965c1..7e522103fd 100644 --- a/drivers/rtc/emul_rtc.c +++ b/drivers/rtc/emul_rtc.c @@ -8,6 +8,7 @@ #include <common.h> #include <div64.h> #include <dm.h> +#include <env.h> #include <generated/timestamp_autogenerated.h> #include <rtc.h>
@@ -60,9 +61,18 @@ static int emul_rtc_set(struct udevice *dev, const struct rtc_time *time) int emul_rtc_probe(struct udevice *dev) { struct emul_rtc *priv = dev_get_priv(dev); - - /* Use the build date as initial time */ - priv->offset_us = U_BOOT_EPOCH * 1000000ULL - timer_get_us(); + const char *epoch_str; + u64 epoch; + + epoch_str = env_get("rtc_emul_epoch"); + + if (epoch_str) { + epoch = simple_strtoull(epoch_str, NULL, 10); + } else { + /* Use the build date as initial time */ + epoch = U_BOOT_EPOCH; + } + priv->offset_us = epoch * 1000000ULL - timer_get_us(); priv->isdst = -1;
return 0; -- 2.28.0