[PATCH v2 2/3] watchdog: rti_wdt: Add support for loading firmware

[Lokesh Vutla]

On 29/06/20 10:20 am, Jan Kiszka wrote:
> On 29.06.20 04:26, Lokesh Vutla wrote:
>> +Tom
>>
>> On 23/06/20 8:11 pm, Jan Kiszka wrote:
>>> On 23.06.20 14:37, Jan Kiszka wrote:
>>>> On 23.06.20 13:50, Lokesh Vutla wrote:
>>>>>
>>>>>
>>>>> On 23/06/20 4:45 pm, Jan Kiszka wrote:
>>>>>> From: Jan Kiszka <jan.kiszka at 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. The firmware itself is
>>>>>> embedded into U-Boot binary.
>>>>>>
>>>>>> One possible firmware source is https://github.com/siemens/k3-rti-wdt.
>>>>>>
>>>>>> Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
>>>>>> ---
>>>>>>    drivers/watchdog/Kconfig      | 20 ++++++++++++++++++++
>>>>>>    drivers/watchdog/Makefile     |  3 +++
>>>>>>    drivers/watchdog/rti_wdt.c    | 24 ++++++++++++++++++++++++
>>>>>>    drivers/watchdog/rti_wdt_fw.S | 20 ++++++++++++++++++++
>>>>>>    4 files changed, 67 insertions(+)
>>>>>>    create mode 100644 drivers/watchdog/rti_wdt_fw.S
>>>>>>
>>>>>> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
>>>>>> index ee99bd2af1..fd6ab9a85b 100644
>>>>>> --- a/drivers/watchdog/Kconfig
>>>>>> +++ b/drivers/watchdog/Kconfig
>>>>>> @@ -162,6 +162,26 @@ 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.
>>>>>> +
>>>>>> +endif
>>>>>> +
>>>>>>    config WDT_SANDBOX
>>>>>>        bool "Enable Watchdog Timer support for Sandbox"
>>>>>>        depends on SANDBOX && WDT
>>>>>> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
>>>>>> index 16bdbf4970..bf58684875 100644
>>>>>> --- a/drivers/watchdog/Makefile
>>>>>> +++ b/drivers/watchdog/Makefile
>>>>>> @@ -28,7 +28,10 @@ obj-$(CONFIG_WDT_MT7621) += mt7621_wdt.o
>>>>>>    obj-$(CONFIG_WDT_MTK) += mtk_wdt.o
>>>>>>    obj-$(CONFIG_WDT_OMAP3) += omap_wdt.o
>>>>>>    obj-$(CONFIG_WDT_K3_RTI) += rti_wdt.o
>>>>>> +obj-$(CONFIG_WDT_K3_RTI_LOAD_FW) += rti_wdt_fw.o
>>>>>>    obj-$(CONFIG_WDT_SP805) += sp805_wdt.o
>>>>>>    obj-$(CONFIG_WDT_STM32MP) += stm32mp_wdt.o
>>>>>>    obj-$(CONFIG_WDT_TANGIER) += tangier_wdt.o
>>>>>>    obj-$(CONFIG_WDT_XILINX) += xilinx_wwdt.o
>>>>>> +
>>>>>> +$(obj)/rti_wdt_fw.o: $(shell readlink -f $(CONFIG_WDT_K3_RTI_FW_FILE)) FORCE
>>>>>> diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
>>>>>> index ebe29c7409..38e82a6b6b 100644
>>>>>> --- a/drivers/watchdog/rti_wdt.c
>>>>>> +++ b/drivers/watchdog/rti_wdt.c
>>>>>> @@ -14,6 +14,7 @@
>>>>>>    #include <power-domain.h>
>>>>>>    #include <wdt.h>
>>>>>>    #include <asm/io.h>
>>>>>> +#include <remoteproc.h>
>>>>>>    /* Timer register set definition */
>>>>>>    #define RTIDWDCTRL        0x90
>>>>>> @@ -37,11 +38,16 @@
>>>>>>    #define WDT_PRELOAD_MAX        0xfff
>>>>>> +#define RTI_PROC_ID        0
>>>>>
>>>>> Can we get the rproc id from DT?
>>>>
>>>> You mean, resolve "mcu_r5fss0_core0" to the ID? Doable.
>>>>
>>>
>>> I'm now probing for the first instance of "ti,am654-r5f" compatible. That
>>> excludes usage for the J721E for now, but that one is fine without firmware -
>>> provided there is way to prevent power-down for RTI watchdog otherwise...
>>
>> I was more of thinking to have a DT property to reference R5-core. But anyways,
>> the property is not present in kernel. I am okay with this for now.
>>
>>>
>>>>>
>>>>>> +
>>>>>>    struct rti_wdt_priv {
>>>>>>        phys_addr_t regs;
>>>>>>        unsigned int clk_khz;
>>>>>>    };
>>>>>> +extern const u32 rti_wdt_fw[];
>>>>>> +extern const int rti_wdt_fw_size;
>>>>>
>>>>> FIT is the preferred way of packing images in U-Boot. Can you try using it?
>>>>
>>>> How does that work? Some example for me?
>>>>
>>>
>>> If you happen to refer to fs-loader: That does not target OSPI, our primary use
>>> case.
>>
>> No. I was thinking to pack the image in FIT along with ATF and OPTEE like in
>> k3_fit_atf.sh and register a U_BOOT_FIT_LOADABLE_HANDLER for installing the
>> firmware.
> 
> In case of our board, that image is not processed by U-Boot (only generated).
> Also, processing it from the R5 loader would imply putting remoteproc support
> into that level, duplicating what we have in A53 U-Boot.
> 
>>
>>>
>>>> What benefit would that bring? There are other users of this pattern, e.g.
>>>> board/xilinx/zynqmp/pm_cfg_obj.S.
>>
>> I didn't know U-Boot is accepting this. Tom, is this the preferred way for
>> including firmware images?
>>
>>>>
>>>
>>> The only benefit of an alternative loading mechanism seems to be handling of
>>> larger images from different sources. But that's what I would tackle via boot
>>> scripting and, thus, without this feature. If you only have a few hundred bytes
>>> to embed, like for k3-rti-wdt, you quickly have a lot of overhead with other
>>> approaches.
>>
>> hmm.. Does the build break if firmware is not present?
> 
> Yes, if you configure to include the firmware but specify an invalid path, the
> build breaks.

So, how do we handle the travis CI/gitlab build without this firmware. I am not
sure how xilinx is handling this. It should be the same case in the above
scenario you pointed out.

Thanks and regards,
Lokesh