ACPI support for optee driver

ACPI support for optee driver

[Mayuresh Chitale]

Hi,

I am working on adding APCI support to optee kernel driver and was
considering implementing it in the following way:

- An optee device node would be added to the bios as follows:
Device(OPTE) {
      Name(_HID, ...)
      Name(_CID, ...)
      Name(_DDN, ...)
      Name (_DSD, Package () {
          Package () {
            Package (2) {"method", "smc"}
          }
      })
    }

- The optee kernel driver would then search for \\SB.OPTE device using
acpi_get_handle and parse the node to get the conduit method.

I was wondering if this is the correct way to implement it and if so
do I need to get the OPTE device registered?  Your feedback is really
appreciated.

Thanks,
Mayuresh.

Re: ACPI support for optee driver

[Mika Westerberg]

On Wed, Sep 20, 2017 at 02:17:38PM +0530, Mayuresh Chitale wrote:
> Hi,
> 
> I am working on adding APCI support to optee kernel driver and was
> considering implementing it in the following way:
> 
> - An optee device node would be added to the bios as follows:
> Device(OPTE) {
>       Name(_HID, ...)
>       Name(_CID, ...)
>       Name(_DDN, ...)
>       Name (_DSD, Package () {
>           Package () {
>             Package (2) {"method", "smc"}
>           }

This _DSD is malformed as it is missing UUID.

>       })
>     }
> 
> - The optee kernel driver would then search for \\SB.OPTE device using
> acpi_get_handle and parse the node to get the conduit method.

You can use the standard device_property_* (see
include/linux/property.h) accessors which fully support _DSD device
properties.

> I was wondering if this is the correct way to implement it and if so
> do I need to get the OPTE device registered?  Your feedback is really
> appreciated.

There is something documented here:

Documentation/acpi/DSD-properties-rules.txt

Re: ACPI support for optee driver

[Mayuresh Chitale]

On 9/20/17, Mika Westerberg <mika.westerberg@linux.intel.com> wrote:
> On Wed, Sep 20, 2017 at 02:17:38PM +0530, Mayuresh Chitale wrote:
>> Hi,
>>
>> I am working on adding APCI support to optee kernel driver and was
>> considering implementing it in the following way:
>>
>> - An optee device node would be added to the bios as follows:
>> Device(OPTE) {
>>       Name(_HID, ...)
>>       Name(_CID, ...)
>>       Name(_DDN, ...)
>>       Name (_DSD, Package () {
>>           Package () {
>>             Package (2) {"method", "smc"}
>>           }
>
> This _DSD is malformed as it is missing UUID.
Actually it is present in the code. I just wanted to present the
required details. Sorry for the ambiguity.
>
>>       })
>>     }
>>
>> - The optee kernel driver would then search for \\SB.OPTE device using
>> acpi_get_handle and parse the node to get the conduit method.
>
> You can use the standard device_property_* (see
> include/linux/property.h) accessors which fully support _DSD device
> properties.
>
>> I was wondering if this is the correct way to implement it and if so
>> do I need to get the OPTE device registered?  Your feedback is really
>> appreciated.
>
> There is something documented here:
>
> Documentation/acpi/DSD-properties-rules.txt
>
In DT, the optee node is placed under the firmware directory but I
dont think there is any equivalent to that in ACPI so I added the
'OPTE' node. I was wondering if this needs to be registered with
UEFI/ACPI forum.

Re: ACPI support for optee driver

[Mika Westerberg]

On Wed, Sep 20, 2017 at 10:07:05PM +0530, Mayuresh Chitale wrote:
> On 9/20/17, Mika Westerberg <mika.westerberg@linux.intel.com> wrote:
> > On Wed, Sep 20, 2017 at 02:17:38PM +0530, Mayuresh Chitale wrote:
> >> Hi,
> >>
> >> I am working on adding APCI support to optee kernel driver and was
> >> considering implementing it in the following way:
> >>
> >> - An optee device node would be added to the bios as follows:
> >> Device(OPTE) {
> >>       Name(_HID, ...)
> >>       Name(_CID, ...)
> >>       Name(_DDN, ...)
> >>       Name (_DSD, Package () {
> >>           Package () {
> >>             Package (2) {"method", "smc"}
> >>           }
> >
> > This _DSD is malformed as it is missing UUID.
> Actually it is present in the code. I just wanted to present the
> required details. Sorry for the ambiguity.
> >
> >>       })
> >>     }
> >>
> >> - The optee kernel driver would then search for \\SB.OPTE device using
> >> acpi_get_handle and parse the node to get the conduit method.
> >
> > You can use the standard device_property_* (see
> > include/linux/property.h) accessors which fully support _DSD device
> > properties.
> >
> >> I was wondering if this is the correct way to implement it and if so
> >> do I need to get the OPTE device registered?  Your feedback is really
> >> appreciated.
> >
> > There is something documented here:
> >
> > Documentation/acpi/DSD-properties-rules.txt
> >
> In DT, the optee node is placed under the firmware directory but I
> dont think there is any equivalent to that in ACPI so I added the
> 'OPTE' node. I was wondering if this needs to be registered with
> UEFI/ACPI forum.

No, I don't think ACPI node names need to be registered anywhere. Just
as long as you don't use the reserved ones, like _SB and PCI0 and on.