[PATCH v6 0/4] clocksource/drivers/timer-vt8500: clean up and add watchdog function

[Alexey Charkov <alchark@gmail.com>]

Add named defines for the registers and bits in timer-vt8500.
Move the system events timer from channel 0 to channel 1 when enough
information is provided by the device tree (i.e. more than one IRQ).
Use channel 0 for the system watchdog, and let the watchdog restart the
SoC, which the machine's own restart hook fails to do on WM8950.

Signed-off-by: Alexey Charkov <alchark@gmail.com>
---
Changes in v6:
- Dropped the binding patch, which Rob has applied
- Rebased onto next-20261111
- Moved the shared header under include/clocksource (thanks Daniel)
- Pass the watchdog a single register base, and keep the watchdog
  register offsets in its own driver (thanks Daniel)
- Build the watchdog driver in rather than as a module: the timer it
  depends on is always built in, and the driver is tiny (thanks Daniel)
- kfree the correct structure upon aux child release (thanks Daniel)
- Return -ENODEV rather than -ENOMEM if the timer failed to initialize,
  and drop the message on allocation failure (thanks Daniel)
- Unmap the timer registers if its interrupt is missing, so that no
  watchdog gets created on a timer that never started
- Improved code comments and commit messages (thanks Daniel)
- Give the watchdog a default timeout, so that opening the device
  before setting one no longer arms it for the next counter wraparound
- Wait for a pending match register write to settle before rewriting it,
  as the clock event code does
- Honour the nowayout parameter, and disallow unbinding the watchdog,
  which would leave it armed with nothing to ping it
- Added a restart handler, so that reboot works on WM8950
- Link to v5: https://lore.kernel.org/r/20250521-vt8500-timer-updates-v5-0-7e4bd11df72e@gmail.com

Changes in v5:
- Make sure the watchdog timeout value is clamped to hardware limits
  before writing it to the registers (thanks Guenter)
- Add a comment about the watchdog match value (deadline) wrapping around
  the U32_MAX boundary, which is expected behavior (thanks Guenter)
- Avoid moving register definitions to the shared header file to reduce
  churn: the watchdog driver gets direct pointers to the two registers it
  uses anyway, so it doesn't have to know all those offsets and bits
- Put the watchdog Kconfig entry with other ARM platforms where it belongs
- Link to v4: https://lore.kernel.org/r/20250521-vt8500-timer-updates-v4-0-2d4306a16ae4@gmail.com

Changes in v4:
- Changed the watchdog driver to use auxiliary bus instead of platform
  (thanks Guenter)
- Split out the register definitions into a header file shared between
  the clocksource driver and the watchdog driver
- Replaced -1UL with U32_MAX in watchdog max_heartbeat_ms to make builds
  on non-32bit platforms happier
- Link to v3: https://lore.kernel.org/r/20250515-vt8500-timer-updates-v3-0-2197a1b062bd@gmail.com

Changes in v3:
- Dropped the DTS patch already applied by Krzysztof
- Rebased onto v6.15-rc5 as requested by Daniel
- Split out the watchdog code into a dedicated platform driver, like
  timer-gxp does (thanks Daniel)
- Link to v2: https://lore.kernel.org/r/20250507-vt8500-timer-updates-v2-0-65e5d1b0855e@gmail.com

Changes in v2:
- Included the previously reviewed binding change that is directly related
  to this series as the first patch here (thanks Krzysztof)
- Created a separate config symbol for the watchdog function to let users
  build a kernel without forcing watchdog functionality upon them
  (thanks Krzysztof)
- Link to the previous binding submission: https://lore.kernel.org/all/20250506-via_vt8500_timer_binding-v3-1-88450907503f@gmail.com/

---
Alexey Charkov (4):
      clocksource/drivers/timer-vt8500: Add defines for magic constants
      clocksource/drivers/timer-vt8500: Prepare for watchdog functionality
      watchdog: Add support for VIA/WonderMedia SoC watchdog functionality
      watchdog: vt8500: Add a restart handler

 Documentation/watchdog/watchdog-parameters.rst |   7 +
 MAINTAINERS                                    |   2 +
 drivers/clocksource/Kconfig                    |   1 +
 drivers/clocksource/timer-vt8500.c             | 179 +++++++++++++++++++++----
 drivers/watchdog/Kconfig                       |  12 ++
 drivers/watchdog/Makefile                      |   1 +
 drivers/watchdog/vt8500-wdt.c                  | 145 ++++++++++++++++++++
 include/clocksource/vt8500-timer.h             |  22 +++
 8 files changed, 342 insertions(+), 27 deletions(-)
---
base-commit: aaa2f954c21b205a0bcd0961e5b2be4e82e58455
change-id: 20250506-vt8500-timer-updates-44a0d22cd720

Best regards,
--  
Alexey Charkov <alchark@gmail.com>