On 08/18/2013 02:37 AM, Alexandre Courbot wrote: > On Thu, Aug 15, 2013 at 6:35 AM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote: >> On 08/12/2013 08:29 PM, Alexandre Courbot wrote: >>> Trusted Foundations is a TrustZone-based secure monitor for ARM that >>> can be invoked using a consistent smc-based API on all supported >>> platforms. This patch adds initial basic support for Trusted >>> Foundations using the ARM firmware API. Current features are limited >>> to the ability to boot secondary processors. >> >>> diff --git a/Documentation/devicetree/bindings/arm/firmware/tl,trusted-foundations.txt b/Documentation/devicetree/bindings/arm/firmware/tl,trusted-foundations.txt >> >>> +Trusted Foundations >>> + >>> +Boards that use the Trusted Foundations secure monitor can signal its >>> +presence by declaring a node compatible with "tl,trusted-foundations" >>> +(the name and location of the node does not matter). >>> + >>> +Required properties: >>> +- compatible : "tl,trusted-foundations" >> >>> +- version : Must contain the version number string of the Trusted Foundation >>> + firmware. >> >> Can the version be queried at run-time from the firmware itself? > > I'm afraid there is not, unfortunately. :/ > >> If not, I wonder if we shouldn't instead encode the version number into >> the compatible value. > > Why? This would make the node harder to find and would also complicate > the case where a given firmware handler can support a given range of > versions (which is what I expect will happen). I guess that would be painful. There are probably a lot more valid version numbers for a SW firmware interface than there are for a HW IP block interface, so it makes less sense to encoded the version into the compatible value, at least in cases where the interface is "similar enough"; we can add some kind of basic version number into the compatible values for radically different interfaces if they appear in the future. >>> diff --git a/arch/arm/firmware/Kconfig b/arch/arm/firmware/Kconfig >> >>> +config ARCH_SUPPORTS_TRUSTED_FOUNDATIONS >>> + bool >> >> Shouldn't that be "config ARCH_SUPPORTS_FIRMWARE", since presumably in >> the future there will be more entries in the menu, and hence we want the >> menu to appear if any of those entries are useful? > > The things is that because you support one firmware does not mean you > will support then all. Only some set of architectures will support > firmware X, and another set (maybe not inclusive) will support > firmware Y. We do not want to allow selecting firmware Y if the kernel > does not support any of the architectures that may make use of it. > >>> + >>> +menu "Firmware options" >>> + depends on ARCH_SUPPORTS_TRUSTED_FOUNDATIONS >> >> Or perhaps that comment is more appropriate for that "depends". > > Here the idea is to not show the "Firmware options" menu if the kernel > does not include support for any architecture that uses them. As more > firmwares get added, the depends line should expand into something > like "depends on ARCH_SUPPORTS_FIRMWARE_X || ARCH_SUPPORTS_FIRMWARE_Y > || ... > > Maybe there's a better way to express this? Is there a need for a menu at all? I suppose it might group things nicely. If so, how about: config ARCH_SUPPORTS_FIRMWARE bool config ARCH_SUPPORTS_TRUSTED_FOUNDATIONS bool select ARCH_SUPPORTS_FIRMWARE config ARCH_SUPPORTS_SOME_OTHER_FW bool select ARCH_SUPPORTS_FIRMWARE menu "Firmware options" depends on ARCH_SUPPORTS_FIRMWARE That's probably slightly easier to read than a huge "depends" statement in the menu stanza, and ARCH_SUPPORTS_FIRMWARE might be a useful to build in support for any core firmware utility code. -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
