[PATCH v4 0/2] renesas: Renesas R-Car Gen4 watchdog driver

[Shmuel Leib Melamud via B4 Relay]

These series add support of Renesas R-Car Gen4 watchdog timer.
Timeouts up to 8184.0s are supported (CKS1 register is not involved).
The watchdog uses the clock type CLK_TYPE_GEN4_MDSEL, so a separate
patch adds handling of this constant to gen3_clk_get_rate64() function.

The series were tested on real Renesas R8A779F0 hardware. If the
watchdog driver is enabled at the build time, the watchdog timer is
initialized when U-Boot starts. Under normal circumstances, U-Boot loads
the kernel, it starts systemd and systemd continues to pet the watchdog.
If systemd is not started before the timeout expires, the watchdog
resets the board.

Signed-off-by: Shmuel Leib Melamud <smelamud at redhat.com>

---
Changes in v4:
- Added #define for the maximal counter value.
- Sorted list of #includes.
- Prefer (a) parameter of usleep_range(a, b)
- Added a comment to the loop that finds the best clock divider.
- Link to v3: https://lore.kernel.org/r/20250603-us-renesas-watchdog-v3-0-af3a65afd03e@redhat.com

Changes in v3:
- Reference to the Linux driver added.
- Clock driver change moved to a separate patch.
- rwdt_ prefix used everywhere instead of renesas_wdt_.
- Disable the clock if rwdt_probe() fails.
- List of compatibles updated.
- Link to v2: https://lore.kernel.org/r/20250530-us-renesas-watchdog-v2-1-b0d8f96c64dc@redhat.com

---
Shmuel Leib Melamud (2):
      clk: renesas: Handle CLK_TYPE_GEN4_MDSEL in gen3_clk_get_rate64()
      renesas: Renesas R-Car Gen4 watchdog driver

 drivers/clk/renesas/clk-rcar-gen3.c |   4 +-
 drivers/watchdog/Kconfig            |   8 ++
 drivers/watchdog/Makefile           |   1 +
 drivers/watchdog/renesas_wdt.c      | 189 ++++++++++++++++++++++++++++++++++++
 4 files changed, 201 insertions(+), 1 deletion(-)
---
base-commit: 3b6760ddeb4ef940226921017cd9088c89784b01
change-id: 20250530-us-renesas-watchdog-2c79dbbd5cd2

Best regards,
-- 
Shmuel Leib Melamud <smelamud at redhat.com>