On 12 November 2015 at 21:33, Rob Herring <robh@xxxxxxxxxx> wrote: > On Thu, Nov 12, 2015 at 04:24:50PM +0000, Peter Maydell wrote: >> The existing device tree bindings assume that we are only trying to >> describe a single address space with a device tree (for ARM, either >> the Normal or the Secure world). Some uses for device tree need to >> describe both Normal and Secure worlds in a single device tree. Add >> documentation of how to do this, by adding extra properties which >> describe when a device appears differently in the two worlds or when >> it only appears in one of them. >> >> The binding describes the general principles for adding new >> properties describing the secure world, but for now we only need a >> single new property, "secure-status", which can be used to annotate >> devices to indicate that they are only visible in one of the two >> worlds. >> >> The primary expected use of this binding is for a virtual machine >> like QEMU to describe the VM layout to a TrustZone aware firmware >> (which would then use the secure-only devices itself, and pass the DT >> on to a kernel running in the non-secure world, which ignores the >> secure-only devices and uses the rest). >> >> Signed-off-by: Peter Maydell <peter.maydell@xxxxxxxxxx> > > I'd specifically like Mark's ack on this one. > >> --- >> This binding doesn't affect the kernel itself, but the kernel >> Documentation/ tree is the de-facto current place where all DT >> bindings are documented, so Grant suggested this was the right >> place to send a doc patch. >> >> Changes v1->v2: >> * list all the status/secure-status combinations explicitly >> * use /* */ comment syntax, not // >> >> Documentation/devicetree/bindings/arm/secure.txt | 51 ++++++++++++++++++++++++ >> 1 file changed, 51 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/arm/secure.txt >> >> diff --git a/Documentation/devicetree/bindings/arm/secure.txt b/Documentation/devicetree/bindings/arm/secure.txt >> new file mode 100644 >> index 0000000..7ed5ed6 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/arm/secure.txt >> @@ -0,0 +1,51 @@ >> +* ARM Secure world bindings >> + >> +ARM CPUs with TrustZone support have two distinct address spaces, >> +"Normal" and "Secure". Most devicetree consumers (including the Linux >> +kernel) are not TrustZone aware and run entirely in either the Normal >> +world or the Secure world. However some devicetree consumers are >> +TrustZone aware and need to be able to determine whether devices are >> +visible only in the Secure address space, only in the Normal address >> +space, or visible in both. (One example of that situation would be a >> +virtual machine which boots Secure firmware and wants to tell the >> +firmware about the layout of the machine via devicetree.) >> + >> +The general principle of the naming scheme for Secure world bindings >> +is that any property that needs a different value in the Secure world >> +can be supported by prefixing the property name with "secure-". So for >> +instance "secure-reg" would override "reg". If there is no "secure-" > > I'd prefer this be "secure-foo" and "foo", rather than reg given I > specifically have a differing opinion on how to support reg. > > Also, would it be secure-vendor,foo or vendor,secure-foo for properties > with vendor prefix? The latter looks more correct to me, but the former > would be easier to search for both variants of the property. I'd lean > towards the latter. OK, so how about making that para read: + The general principle of the naming scheme for Secure world bindings + is that any property that needs a different value in the Secure world + can be supported by prefixing the property name with "secure-". So for + instance "secure-foo" would override "foo". For property names with + a vendor prefix, the Secure variant of "vendor,foo" would be + "vendor,secure-foo". If there is no "secure-" property then the Secure + world value is the same as specified for the Normal world by the + non-prefixed property. However, only the properties listed below may + validly have "secure-" versions; this list will be enlarged on a + case-by-case basis. thanks -- PMM -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
