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

From: Jan Kiszka <jan.kiszka@siemens.com>
To: Lokesh Vutla <lokeshvutla@ti.com>,
	U-Boot Mailing List <u-boot@lists.denx.de>
Cc: Le Jin <le.jin@siemens.com>,
	Bao Cheng Su <baocheng.su@siemens.com>,
	Nian Gao <nian.gao@siemens.com>,
	Chao Zeng <chao.zeng@siemens.com>, Tom Rini <trini@konsulko.com>
Subject: Re: [PATCH v2 4/5] watchdog: rti_wdt: Add support for loading firmware
Date: Mon, 7 Jun 2021 12:20:29 +0200	[thread overview]
Message-ID: <5c777240-9bc6-b655-f9b2-cabc758cda4c@siemens.com> (raw)
In-Reply-To: <96039724-9a5f-dbb8-d46b-b268a0d9a8c2@ti.com>

On 07.06.21 12:03, Lokesh Vutla wrote:
> +Tom,
> 
> Hi Tom,
> 
> On 02/06/21 3:07 pm, Jan Kiszka wrote:
>> From: Jan Kiszka <jan.kiszka@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@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?
> 

It's specific to this driver - on a subset of supported hardware
platforms, namely AM65x SR1.0.

Jan

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