Hi Rob, Thank you for the review. On Thu, Jan 2, 2025 at 9:46 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > On Fri, Dec 27, 2024 at 07:02:08PM +0000, Prabhakar wrote: > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> > > > > The RZ/V2H(P) CPG block includes Error Reset Registers (CPG_ERROR_RSTm). > > A system reset is triggered in response to error interrupt factors, and > > the corresponding bit is set in the CPG_ERROR_RSTm register. These > > registers can be utilized by various IP blocks as needed. > > > > In the event of a watchdog overflow or underflow, a system reset is issued, > > and the CPG_ERROR_RST2[0/1/2/3] bits are set depending on the watchdog in > > use: CM33 = 0, CA55 = 1, CR8_0 = 2, CR8_1 = 3. For the watchdog driver to > > determine and report the current boot status, it needs to read the > > CPG_ERROR_RST2[0/1/2/3]bits and provide this information to the user upon > > request. > > > > To facilitate this operation, add `renesas,syscon-cpg-error-rst` > > property to the WDT node, which maps to the `syscon` CPG node, enabling > > retrieval of the necessary information. > > > > Additionally, the property is marked as required for the RZ/V2H(P) SoC to > > ensure future compatibility (e.g., where the same IP block is present on > > the RZ/G3E SoC) and explicitly disallowed for other SoCs. > > This is the other half of the ABI change. > > > > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx> > > --- > > v1->v2 > > - Renamed `renesas,r9a09g057-syscon-wdt-errorrst` to `renesas,syscon-cpg-error-rst` > > - Updated commit message > > --- > > .../bindings/watchdog/renesas,wdt.yaml | 17 +++++++++++++++++ > > 1 file changed, 17 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/watchdog/renesas,wdt.yaml b/Documentation/devicetree/bindings/watchdog/renesas,wdt.yaml > > index 29ada89fdcdc..ca62ae8b1b0c 100644 > > --- a/Documentation/devicetree/bindings/watchdog/renesas,wdt.yaml > > +++ b/Documentation/devicetree/bindings/watchdog/renesas,wdt.yaml > > @@ -112,6 +112,19 @@ properties: > > > > timeout-sec: true > > > > + renesas,syscon-cpg-error-rst: > > + $ref: /schemas/types.yaml#/definitions/phandle-array > > + description: > > + The first cell is a phandle to the SYSCON entry required to obtain > > + the current boot status. The second cell specifies the CPG_ERROR_RSTm > > + register offset within the SYSCON, and the third cell indicates the > > + bit within the CPG_ERROR_RSTm register. > > + items: > > + - items: > > + - description: Phandle to the CPG node > > + - description: The CPG_ERROR_RSTm register offset > > + - description: The bit within CPG_ERROR_RSTm register of interest > > + > > required: > > - compatible > > - reg > > @@ -182,7 +195,11 @@ allOf: > > properties: > > interrupts: false > > interrupt-names: false > > + required: > > + - renesas,syscon-cpg-error-rst > > New required property == ABI break > > Once the OS driver relies on this being present, then older DTs will > break. > In this case there is no ABI break, as the driver code [0] does not fail the probe when the property does not exist, it's just that it won't report the status of current boot. [0] https://lore.kernel.org/all/20241227190210.69025-6-prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx/ Cheers, Prabhakar
