[PATCH v4 1/3] dt-bindings: watchdog: ti,rti-wdt: Add support for WDIOF_CARDRESET

[Li, Hua Qian]

On Sun, 2023-07-16 at 22:15 -0700, Guenter Roeck wrote:
> On 7/16/23 21:07, huaqian.li at siemens.com wrote:
> > From: Li Hua Qian <huaqian.li at siemens.com>
> > 
> > TI RTI (Real Time Interrupt) Watchdog doesn't support to record the
> > watchdog cause. Add a reserved memory to know the last reboot was
> > caused
> > by the watchdog card. In the reserved memory, some specific info
> > will be
> > saved to indicate whether the watchdog reset was triggered in last
> > boot.
> > 
> > Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski at linaro.org>
> > Reviewed-by: Conor Dooley <conor at kernel.org>
> > Reviewed-by: Rob Herring <robh at kernel.org>
> > Signed-off-by: Li Hua Qian <huaqian.li at siemens.com>
> 
> Reviewed-by: Guenter Roeck <linux at roeck-us.net>
Hi Guenter,

I'm going to integrate it with the existing binding as Krzysztof
suggested, could I leave you in `Reviewed-by`?

   59 examples:                                                       
   60   - |                                                           
   61     /*                                                          
   62      * RTI WDT in main domain on J721e SoC. Assigned clocks are
used to                                                               
   63      * select the source clock for the watchdog, forcing it to
tick with                                                             
~  64      * a 32kHz clock in this case. Add a reserved
memory(optional) to keep                                              
~_ 65      * the watchdog reset cause persistent, which was be written
in 12 bytes                                                           
   66      * starting from 0xa2200000 by RTI Watchdog Firmware.       
   67      *                                                          
   68      * Reserved memory should be defined as follows:            
   69      * reserved-memory {                                        
   70      *     wdt_reset_memory_region: wdt-memory at a2200000 {       
   71      *         reg = <0x00 0xa2200000 0x00 0x1000>;             
   72      *         no-map;                                          
   73      *     };                                                   
   74      * }                                                        
   75      */                                                         
~  76     #include <dt-bindings/soc/ti,sci_pm_domain.h>               
+  77                                                                 
+  78     watchdog at 2200000 {                                          
   79         compatible = "ti,j7-rti-wdt";                           
~  80         reg = <0x2200000 0x100>;                                
~  81         clocks = <&k3_clks 252 1>;                              
~  82         power-domains = <&k3_pds 252 TI_SCI_PD_EXCLUSIVE>;      
~  83         assigned-clocks = <&k3_clks 252 1>;                     
~  84         assigned-clock-parents = <&k3_clks 252 5>;              
   85         memory-region = <&wdt_reset_memory_region>;             
   86     };                                                          

Best regards,
Li Hua Qian                                                           
> 
> > ---
> >   .../bindings/watchdog/ti,rti-wdt.yaml         | 41
> > +++++++++++++++++++
> >   1 file changed, 41 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/watchdog/ti,rti-
> > wdt.yaml b/Documentation/devicetree/bindings/watchdog/ti,rti-
> > wdt.yaml
> > index fc553211e42d..4b66c4fcdf35 100644
> > --- a/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml
> > +++ b/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml
> > @@ -34,6 +34,20 @@ properties:
> >     power-domains:
> >       maxItems: 1
> >   
> > +  memory-region:
> > +    maxItems: 1
> > +    description:
> > +      Contains the watchdog reserved memory. It is optional.
> > +      In the reserved memory, the specified values, which are
> > +      PON_REASON_SOF_NUM(0xBBBBCCCC),
> > PON_REASON_MAGIC_NUM(0xDDDDDDDD),
> > +      and PON_REASON_EOF_NUM(0xCCCCBBBB), are pre-stored at the
> > first
> > +      3 * 4 bytes to tell that last boot was caused by watchdog
> > reset.
> > +      Once the PON reason is captured by driver(rti_wdt.c), the
> > driver
> > +      is supposed to wipe the whole memory region. Surely, if this
> > +      property is set, at least 12 bytes reserved memory starting
> > from
> > +      specific memory address(0xa220000) should be set. More
> > please
> > +      refer to Example 2.
> > +
> >   required:
> >     - compatible
> >     - reg
> > @@ -59,3 +73,30 @@ examples:
> >           assigned-clocks = <&k3_clks 252 1>;
> >           assigned-clock-parents = <&k3_clks 252 5>;
> >       };
> > +
> > +  - |
> > +    // Example 2 (Add reserved memory for watchdog reset cause):
> > +    /*
> > +     * RTI WDT in main domain on J721e SoC. Assigned clocks are
> > used to
> > +     * select the source clock for the watchdog, forcing it to
> > tick with
> > +     * a 32kHz clock in this case. Add a reserved memory to keep
> > the
> > +     * watchdog reset cause persistent, which was be written in 12
> > bytes
> > +     * starting from 0xa2200000 by RTI Watchdog Firmware.
> > +     *
> > +     * Reserved memory should be defined as follows:
> > +     * reserved-memory {
> > +     *     wdt_reset_memory_region: wdt-memory at a2200000 {
> > +     *         reg = <0x00 0xa2200000 0x00 0x1000>;
> > +     *         no-map;
> > +     *     };
> > +     * }
> > +     */
> > +    watchdog at 40610000 {
> > +        compatible = "ti,j7-rti-wdt";
> > +        reg = <0x40610000 0x100>;
> > +        clocks = <&k3_clks 135 1>;
> > +        power-domains = <&k3_pds 135 TI_SCI_PD_EXCLUSIVE>;
> > +        assigned-clocks = <&k3_clks 135 0>;
> > +        assigned-clock-parents = <&k3_clks 135 4>;
> > +        memory-region = <&wdt_reset_memory_region>;
> > +    };
>