[PATCH v3 0/4] rtc: pcf85063: Update interrupt support

[A. Sverdlin]

From: Alexander Sverdlin <alexander.sverdlin@xxxxxxxxxxx>

Add hardware-backed UIE (1 Hz update interrupt) support to the pcf85063
driver. The PCF85063A/RV8263 have no dedicated update-interrupt source,
so chrony and similar tools that rely on RTC_UIE_ON fall back to the
kernel's software polling emulation. This series repurposes the chip's
countdown timer (TCF = 1 Hz, T = 1) to generate a periodic interrupt on
the INT pin, serving UIE entirely in hardware.

Patches 2-3 are preparatory: they fix an AIE race in the interrupt
handler and a lost-alarm-flag race in the clkout helpers.

Patch 1 fixes a pre-existing use-after-free in the clkout clock provider
on unbind, found during review by Sashiko.

Changelog:
v3:
- split into 3 preparatory patches and the final new feature patch
- replaced racy regmap_write() with regmap_update_bits() in IRQ handler
- the timer flag (TF) is write-0-to-clear, so every read-modify-write of
  CTRL2 preserves it by writing it back as 1
v2:
- https://lore.kernel.org/all/20260820112437.3715237-1-alexander.sverdlin@xxxxxxxxxxx/

Alexander Sverdlin (4):
  rtc: pcf85063: use devm_of_clk_add_hw_provider() for clkout
  rtc: pcf85063: do not clear AIE in the interrupt handler
  rtc: pcf85063: preserve the alarm flag in clkout register updates
  rtc: pcf85063: add 1 Hz update interrupt (UIE) support

 drivers/rtc/rtc-pcf85063.c | 139 +++++++++++++++++++++++++++++++------
 1 file changed, 118 insertions(+), 21 deletions(-)

-- 
2.55.0