[PATCH v7 01/10] spl: Kconfig: allow K3 devices to use falcon mode

[Anshul Dalal]

On Mon Jun 9, 2025 at 8:29 PM IST, Tom Rini wrote:
> On Mon, Jun 09, 2025 at 05:38:37PM +0530, Anshul Dalal wrote:
>> On Sat Jun 7, 2025 at 12:36 AM IST, Tom Rini wrote:
>> > On Tue, Jun 03, 2025 at 07:54:41PM +0530, Anshul Dalal wrote:
>> >
>> >> Falcon mode was disabled for TI_SECURE_DEVICE at commit e95b9b4437bc
>> >> ("ti_armv7_common: Disable Falcon Mode on HS devices") for older 32-bit
>> >> HS devices and can be enabled on K3 devices.
>> >> 
>> >> For secure boot, the kernel with x509 headers can be packaged in a fit
>> >> container (fitImage) signed with TIFS keys for authentication.
>> >> 
>> >> Signed-off-by: Anshul Dalal <anshuld at ti.com>
>> >> ---
>> >>  common/spl/Kconfig | 2 +-
>> >>  1 file changed, 1 insertion(+), 1 deletion(-)
>> >> 
>> >> diff --git a/common/spl/Kconfig b/common/spl/Kconfig
>> >> index 77cf04d38ed..bc5a334a1c5 100644
>> >> --- a/common/spl/Kconfig
>> >> +++ b/common/spl/Kconfig
>> >> @@ -1190,7 +1190,7 @@ config SPL_ONENAND_SUPPORT
>> >>  
>> >>  config SPL_OS_BOOT
>> >>  	bool "Activate Falcon Mode"
>> >> -	depends on !TI_SECURE_DEVICE
>> >> +	depends on !TI_SECURE_DEVICE || ARCH_K3
>> >>  	help
>> >>  	  Enable booting directly to an OS from SPL.
>> >>  	  for more info read doc/README.falcon
>> >
>> > I wonder if overloading ARCH_K3 like this isn't a great idea. Or perhaps
>> > TI_SECURE_DEVICE is too generic a name. I kind of want to introduce
>> > something that means TI Secure Boot is supported but also Falcon is
>> > supported, and then use that as how we disable in Kconfig various
>> > insecure options. And I assume that it's a matter of effort not
>> > technical restrictions for supporting falcon mode on older HS parts?
>> 
>> I second your opinion here, the falcon boot flow we do have in K3
>> devices is quite different from existing platforms but still enabled by
>> the same SPL_OS_BOOT config. Perhaps adding a config like K3_FALCON
>> makes sense here.
>> 
>> And yes, older HS *K3* parts should be able to support a similar falcon
>> style boot flow with not much changes to the k3_falcon_prep function.
>
> Maybe we need a common symbol for things that are common to all TI
> secure devices, and other symbols for K3 or AM33xx (or whatever is most
> appropriate for that overall era of parts).

I was thinking of adding TI_SECURE_DEVICE_(LEGACY|K3) hidden config
symbols which TI_SECURE_DEVICE selects as below:

config TI_SECURE_DEVICE
	bool "HS Device Type Support"
	depends on ARCH_KEYSTONE || ARCH_OMAP2PLUS || ARCH_K3
	select TI_SECURE_DEVICE_LEGACY if ARCH_KEYSTONE || ARCH_OMAP2PLUS
	select TI_SECURE_DEVICE_K3 if ARCH_K3

We can then use TI_SECURE_DEVICE_LEGACY to disable OS_BOOT for older non
K3 platforms instead.