Re: [PATCH v2 2/2] rtc: provide an emulated RTC
On 26.10.20 16:31, Grant Likely wrote:
On Mon, Oct 26, 2020 at 3:30 PM Grant Likely grant.likely@secretlab.ca wrote:
On Sun, Oct 25, 2020 at 7:13 AM Heinrich Schuchardt xypron.glpk@gmx.de wrote:
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.
Signed-off-by: Heinrich Schuchardt xypron.glpk@gmx.de
Looks good to me, and tested on RockPro64 w/ UEFI SCT.
Tested-by: Grant Likely grant.likely@arm.com
One thought: Can this be automatically enabled if no other RTC driver is configured in?
* This RTC does not show the correct time unless you use SNTP to set it. * There is no need for an RTC to boot an OS. * Many board maintainers struggle with the size of there U-Boot binary.
So it does not make sense to me to enable this driver as fallback by default.
Best regards
Heinrich
g.
g.
v2: more elaborate Kconfig message adjust device name properties use build time as initial time
MAINTAINERS | 1 + drivers/rtc/Kconfig | 11 ++++++ drivers/rtc/Makefile | 1 + drivers/rtc/emul_rtc.c | 80 ++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 93 insertions(+) create mode 100644 drivers/rtc/emul_rtc.c
diff --git a/MAINTAINERS b/MAINTAINERS index fc4fad46ee..a98e0c5b76 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -678,6 +678,7 @@ S: Maintained T: git https://gitlab.denx.de/u-boot/custodians/u-boot-efi.git F: doc/api/efi.rst F: doc/uefi/* +F: drivers/rtc/emul_rtc.c F: include/capitalization.h F: include/charset.h F: include/cp1250.h diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index 63662001c2..d06d272e14 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -63,6 +63,17 @@ config RTC_DS3232 Support for Dallas Semiconductor (now Maxim) DS3232 compatible Real Time Clock devices.
+config RTC_EMULATION
bool "Enable emulated RTC"depends on DM_RTChelpOn a board without hardware clock this software real time clock can beused. The build time is used to initialize the RTC. So you will haveto adjust the time either manually using the 'date' command or usethe 'sntp' to update the RTC with the time from a network time server.See CONFIG_CMD_SNTP and CONFIG_BOOTP_NTPSERVER. The RTC time isadvanced according to CPU ticks.config RTC_ISL1208 bool "Enable ISL1208 driver" depends on DM_RTC diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile index 12eb449583..ef66dc4bf0 100644 --- a/drivers/rtc/Makefile +++ b/drivers/rtc/Makefile @@ -22,6 +22,7 @@ obj-$(CONFIG_RTC_DS164x) += ds164x.o obj-$(CONFIG_RTC_DS174x) += ds174x.o obj-$(CONFIG_RTC_DS3231) += ds3231.o obj-$(CONFIG_RTC_DS3232) += ds3232.o +obj-$(CONFIG_RTC_EMULATION) += emul_rtc.o obj-$(CONFIG_RTC_FTRTC010) += ftrtc010.o obj-$(CONFIG_SANDBOX) += i2c_rtc_emul.o obj-$(CONFIG_RTC_IMXDI) += imxdi.o diff --git a/drivers/rtc/emul_rtc.c b/drivers/rtc/emul_rtc.c new file mode 100644 index 0000000000..c98c24bbb3 --- /dev/null +++ b/drivers/rtc/emul_rtc.c @@ -0,0 +1,80 @@ +// SPDX-License-Identifier: GPL-2.0+ +/*
- Copyright 2020, Heinrich Schuchardt xypron.glpk@gmx.de
- This driver emulates a real time clock based on timer ticks.
- */
+#include <common.h> +#include <div64.h> +#include <dm.h> +#include <generated/timestamp_autogenerated.h> +#include <rtc.h>
+/**
- struct emul_rtc - private data for emulated RTC driver
- */
+struct emul_rtc {
/*** @offset_us: microseconds from 1970-01-01 to timer_get_us() base*/u64 offset_us;/*** @isdst: daylight saving time*/int isdst;+};
+static int emul_rtc_get(struct udevice *dev, struct rtc_time *time) +{
struct emul_rtc *priv = dev_get_priv(dev);u64 now;if (!priv->offset_us) {/* Use the build date as initial time */priv->offset_us = U_BOOT_EPOCH * 1000000ULL - timer_get_us();priv->isdst = -1;}now = timer_get_us() + priv->offset_us;do_div(now, 1000000);rtc_to_tm(now, time);time->tm_isdst = priv->isdst;return 0;+}
+static int emul_rtc_set(struct udevice *dev, const struct rtc_time *time) +{
struct emul_rtc *priv = dev_get_priv(dev);if (time->tm_year < 1970)return -EINVAL;priv->offset_us = rtc_mktime(time) * 1000000ULL - timer_get_us();if (time->tm_isdst > 0)priv->isdst = 1;else if (time->tm_isdst < 0)priv->isdst = -1;elsepriv->isdst = 0;return 0;+}
+static const struct rtc_ops emul_rtc_ops = {
.get = emul_rtc_get,.set = emul_rtc_set,+};
+U_BOOT_DRIVER(rtc_emul) = {
.name = "rtc_emul",.id = UCLASS_RTC,.ops = &emul_rtc_ops,.priv_auto_alloc_size = sizeof(struct emul_rtc),+};
+U_BOOT_DEVICE(rtc_emul) = {
.name = "rtc_emul",+};
2.28.0
participants (1)
-
Heinrich Schuchardt