Re: [PATCH v2 4/5] watchdog: rti_wdt: Add support for loading firmware

[Jan Kiszka <jan.kiszka@siemens.com>]

On 26.06.21 20:29, Simon Glass wrote:
> Hi,
> 
> On Fri, 11 Jun 2021 at 08:08, Tom Rini <trini@konsulko.com> wrote:
>>
>> On Fri, Jun 11, 2021 at 07:14:21PM +0530, Lokesh Vutla wrote:
>>> Hi Tom,
>>>
>>> On 09/06/21 6:47 pm, Jan Kiszka wrote:
>>>> On 07.06.21 13:44, Jan Kiszka wrote:
>>>>> On 07.06.21 13:40, Tom Rini wrote:
>>>>>> On Mon, Jun 07, 2021 at 03:33:52PM +0530, Lokesh Vutla wrote:
>>>>>>> +Tom,
>>>>>>>
>>>>>>> Hi Tom,
>>>>>>>
>>>>>>> On 02/06/21 3:07 pm, Jan Kiszka wrote:
>>>>>>>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>>>>>>>
>>>>>>>> To avoid the need of extra boot scripting on AM65x for loading a
>>>>>>>> watchdog firmware, add the required rproc init and loading logic for the
>>>>>>>> first R5F core to the watchdog start handler. In case the R5F cluster is
>>>>>>>> in lock-step mode, also initialize the second core. The firmware itself
>>>>>>>> is embedded into U-Boot binary to ease access to it and ensure it is
>>>>>>>> properly hashed in case of secure boot.
>>>>>>>>
>>>>>>>> One possible firmware source is https://github.com/siemens/k3-rti-wdt.
>>>>>>>>
>>>>>>>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>>>>>>>> ---
>>>>>>>>  drivers/watchdog/Kconfig      | 20 ++++++++++++
>>>>>>>>  drivers/watchdog/Makefile     |  5 +++
>>>>>>>>  drivers/watchdog/rti_wdt.c    | 58 ++++++++++++++++++++++++++++++++++-
>>>>>>>>  drivers/watchdog/rti_wdt_fw.S | 20 ++++++++++++
>>>>>>>>  4 files changed, 102 insertions(+), 1 deletion(-)
>>>>>>>>  create mode 100644 drivers/watchdog/rti_wdt_fw.S
>>>>>>>>
>>>>>>>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>>>>>>>> index f0ff2612a6..1a1fddfe9f 100644
>>>>>>>> --- a/drivers/watchdog/Kconfig
>>>>>>>> +++ b/drivers/watchdog/Kconfig
>>>>>>>> @@ -209,6 +209,26 @@ config WDT_K3_RTI
>>>>>>>>           Say Y here if you want to include support for the K3 watchdog
>>>>>>>>           timer (RTI module) available in the K3 generation of processors.
>>>>>>>>
>>>>>>>> +if WDT_K3_RTI
>>>>>>>> +
>>>>>>>> +config WDT_K3_RTI_LOAD_FW
>>>>>>>> +       bool "Load watchdog firmware"
>>>>>>>> +       depends on REMOTEPROC
>>>>>>>> +       help
>>>>>>>> +         Automatically load the specified firmware image into the MCU R5F
>>>>>>>> +         core 0. On the AM65x, this firmware is supposed to handle the expiry
>>>>>>>> +         of the watchdog timer, typically by resetting the system.
>>>>>>>> +
>>>>>>>> +config WDT_K3_RTI_FW_FILE
>>>>>>>> +       string "Watchdog firmware image file"
>>>>>>>> +       default "k3-rti-wdt.fw"
>>>>>>>> +       depends on WDT_K3_RTI_LOAD_FW
>>>>>>>> +       help
>>>>>>>> +         Firmware image to be embedded into U-Boot and loaded on watchdog
>>>>>>>> +         start.
>>>>>>>
>>>>>>> I need your input on this proach. Is it okay to include the linker file unders
>>>>>>> drivers?
>>>>>>
>>>>>> Maybe?  I suppose the first thing that springs to mind is why aren't we
>>>>>> using binman and including this blob (which I happily see is GPLv2)
>>>>>> similar to how we do things with x86 for one example.
>>>>>>
>>>>>
>>>>> See https://www.mail-archive.com/u-boot@lists.denx.de/msg377894.html
>>>>>
>>>>> Jan
>>>>>
>>>>
>>>> Did this help to answer open questions? Otherwise, please let me know.
>>>>
>>>> I'd also like to avoid that his patch alone blocks 1-3 of the series
>>>> needless - but I would also not mind getting everything in at once.
>>>
>>> Can you provide your reviewed-by if you are okay with this approach?
>>
>> I was kind of hoping Simon would chime in here on binman usage.  So,
>> re-re-reading the above URL, yes, fsloader wouldn't be the right choice
>> for watchdog firmware.  But I think binman_entry_find() and related
>> could work, in general, for this case of "need firmware blob embedded in
>> to image".  That said, this isn't just any firmware blob, it's the
>> watchdog firmware.  The less reliance on other things the safer it is.
>> That means this would be an exception to the general firmware blob
>> loading rule and yeah, OK, we can do it this way.  Sorry for the delay.
> 
> Yes I've been a little tied up recently. But I think this should use
> binman. We really don't want to be building binary firmware into
> U-Boot itself!
> 
> Also Tom says, see x86 for a load of binaries of different types and
> how they are accessed at runttime. This is what binman is for.
> 

Please take the time and study my arguments. I'm open for better
proposals, but they need to be concrete and addressing my points.

Thanks,
Jan

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