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

[Lokesh Vutla]

+Tom,

Hi Tom,

On 02/06/21 3:07 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. 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 at 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?

> +
> +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 5c7ef593fe..5016ee4708 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -33,7 +33,12 @@ obj-$(CONFIG_WDT_OCTEONTX) += octeontx_wdt.o
>  obj-$(CONFIG_WDT_OMAP3) += omap_wdt.o
>  obj-$(CONFIG_WDT_SBSA) += sbsa_gwdt.o
>  obj-$(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
> +

[...snip..]

>  	timer_margin = timeout_ms * priv->clk_khz / 1000;
>  	timer_margin >>= WDT_PRELOAD_SHIFT;
>  	if (timer_margin > WDT_PRELOAD_MAX)
> diff --git a/drivers/watchdog/rti_wdt_fw.S b/drivers/watchdog/rti_wdt_fw.S
> new file mode 100644
> index 0000000000..78d99ff9f2
> --- /dev/null
> +++ b/drivers/watchdog/rti_wdt_fw.S

Isn't this usecase specific? IMHO, drivers might not be the right place. Did I
misunderstand something?

Thanks and regards,
Lokesh

> @@ -0,0 +1,20 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (c) Siemens AG, 2020
> + *
> + * Authors:
> + *   Jan Kiszka <jan.kiszka at siemens.com>
> + */
> +
> +.section .rodata
> +
> +.global rti_wdt_fw
> +.global rti_wdt_fw_size
> +
> +rti_wdt_fw:
> +.align 4
> +.incbin CONFIG_WDT_K3_RTI_FW_FILE
> +rti_wdt_fw_end:
> +
> +rti_wdt_fw_size:
> +.int rti_wdt_fw_end - rti_wdt_fw
>