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

Mon Jun 29 14:37:10 CEST 2020

On Mon, Jun 29, 2020 at 07:56:53AM +0530, 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.

Note that not all properties in a DT in Linux need to be used in Linux,
this is something I _think_ there is growing understanding of.

> >>>> +
> >>>>   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?

Adding in Michal.  Why is this area doing what it's doing and not one of
the other generic ways to handle this problem?  Thanks!

-- 
Tom
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