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

Mon Jun 29 06:50:12 CEST 2020

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.

Jan

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