[0/3] rtc: rzn1: support XTAL clk and SCMP method

Message

Wolfram Sang March 19, 2025, 11:03 a.m. UTC

So far, the code and the binding for the RZ/N1D RTC assumed an input
clock of 32768Hz, so it was not explicitly described. It makes sense to
do this, though. For one reason, clocks with other frequencies might be
used. This RTC supports that via the SCMP counting method. The other
reason is, the upcoming R-Car Gen5 has only the SCMP method described,
so we need to use it there later.

This series lets the driver handle the optional "xtal" clock and switch
to the SCMP method if suitable. It has been tested on a Renesas RZ/N1D
board with hacked devicetree values.

A branch with updated DTs can be found here:

git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git renesas/n1d/rtc

Looking forward to comments!


Changes since RFC:
* add binding tag from Krzysztof (Thanks!)
* new patch to disable controller before initially modifying CTL0
* cosmetic changes

Wolfram Sang (3):
  dt-bindings: rtc: rzn1: add optional second clock
  rtc: rzn1: Disable controller before initialization
  rtc: rzn1: support input frequencies other than 32768Hz

 .../bindings/rtc/renesas,rzn1-rtc.yaml        |  8 ++-
 drivers/rtc/rtc-rzn1.c                        | 59 +++++++++++++++----
 2 files changed, 53 insertions(+), 14 deletions(-)