This series adds support for the "robust" real time clock found on the
Freescale MCF5441x family of ColdFire SoCs.
Patch 1 adds the rtc-class driver. Besides the usual time/calendar and a
one-shot alarm, the block contains 2KB of battery-backed standby RAM that
survives a main-power loss while VSTBY_RTC is supplied; the driver exposes
it through the nvmem framework so userspace can persist data (for example a
reset/reboot counter) across power cycles. Register and standby-RAM writes
go through the RTC_CR[WE] knock sequence, the time counters are read under
the RTC_SR[INVAL] guard described in the reference manual, and the time/date
encoding is forced to binary at probe.
Patch 2 registers the platform device from the m5441x ColdFire SoC support
code so that every MCF5441x board gets the RTC. The MCFRTC_BASE, MCFRTC_SIZE
and MCF_IRQ_RTC definitions it relies on already exist in
arch/m68k/include/asm/m5441xsim.h.
The driver has been exercised on an MCF54418-based board: it registers
as an rtc device, exposes the standby RAM as an nvmem device, and a value
written to the standby RAM survives a mains power-cycle.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>
---
Jean-Michel Hautbois (2):
rtc: m5441x: add MCF5441x on-chip RTC driver
m68k: coldfire/m5441x: register the on-chip RTC
MAINTAINERS | 6 +
arch/m68k/coldfire/m5441x.c | 29 +++
drivers/rtc/Kconfig | 12 +
drivers/rtc/Makefile | 1 +
drivers/rtc/rtc-m5441x.c | 582 ++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 630 insertions(+)
---
base-commit: 6f3ed7fec72fc8979b2a8c7219c0a9fcfc8d07b5
change-id: 20260529-jmh-upstream-coldfire-rtc-88b095b2cf28
Best regards,
--
Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org>