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

[Lokesh Vutla]

+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.

> 
>> 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?

Thanks and regards,
Lokesh

> 
> Jan
>