linux-kernel - Re: [PATCH] optee: enable apci support

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Message-ID: <CAMj1kXEfVh-q=cae1RWTVwABYsmX=-OZbWmgRMm4DSK7NjQBEg@mail.gmail.com>
Date:   Thu, 18 Mar 2021 08:47:33 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Ran Wang <ran.wang_1@....com>
Cc:     Jens Wiklander <jens.wiklander@...aro.org>,
        "op-tee@...ts.trustedfirmware.org" <op-tee@...ts.trustedfirmware.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] optee: enable apci support

On Thu, 18 Mar 2021 at 08:29, Ran Wang <ran.wang_1@....com> wrote:
>
> Hi Ard,
>
>
> On Wednesday, March 17, 2021 4:29 PM, Ard Biesheuvel wrote:
> >
> > On Wed, 17 Mar 2021 at 09:04, Jens Wiklander <jens.wiklander@...aro.org> wrote:
> > >
> > > On Fri, Mar 12, 2021 at 04:36:53PM +0800, Ran Wang wrote:
> > > > This patch add ACPI support for optee driver.
> > > >
> > > > Signed-off-by: Ran Wang <ran.wang_1@....com>
> > > > ---
> > > >  drivers/tee/optee/core.c | 10 ++++++++++
> > > >  1 file changed, 10 insertions(+)
> > > >
> > > > diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
> > > > index cf4718c6d35d..8fb261f4b9db 100644
> > > > --- a/drivers/tee/optee/core.c
> > > > +++ b/drivers/tee/optee/core.c
> > > > @@ -5,6 +5,7 @@
> > > >
> > > >  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> > > >
> > > > +#include <linux/acpi.h>
> > > >  #include <linux/arm-smccc.h>
> > > >  #include <linux/errno.h>
> > > >  #include <linux/io.h>
> > > > @@ -735,12 +736,21 @@ static const struct of_device_id
> > > > optee_dt_match[] = {  };  MODULE_DEVICE_TABLE(of, optee_dt_match);
> > > >
> > > > +#ifdef CONFIG_ACPI
> > > > +static const struct acpi_device_id optee_acpi_match[] = {
> > > > +     { "OPTEE01",},
> >
> > You cannot just invent ACPI HIDs like that. The 4 character prefix is a vendor ID that is assigned by the UEFI forum, the 4 following digits are
> > up to the vendor to assign,
>
> Thanks for this info. Could you please show me where I can find the guide/example for this assign process?
>

I think it is better to ask around internally. As far as I know, NXP
already owns a ACPI/PNP vendor prefix.

> > > > +     { },
> > > > +};
> > > > +MODULE_DEVICE_TABLE(acpi, dwc3_acpi_match);
> >
> > dwc3_acpi_match ?? Does this even build?
>
> My bad, I was referring dwc3 code as an example, will correct it.
>
> But looks this typo didn’t trigger error in my unit-test.
>

Does your build have CONFIG_ACPI enabled?

> >
> > > > +#endif
> > > > +
> > > >  static struct platform_driver optee_driver = {
> > > >       .probe  = optee_probe,
> > > >       .remove = optee_remove,
> > > >       .driver = {
> > > >               .name = "optee",
> > > >               .of_match_table = optee_dt_match,
> > > > +             .acpi_match_table = ACPI_PTR(optee_acpi_match),
> > > >       },
> > > >  };
> > > >  module_platform_driver(optee_driver);
> > > > --
> > > > 2.25.1
> > > >
> > >
> > > This looks simple enough. Ard, is this what you had in mind earlier?
> > >
> >
> > Not really.
> >
> > On SynQuacer, we use
> >
> >     Device (TOS0) {
> >       Name (_HID, "PRP0001")
> >       Name (_UID, 0x0)
> >       Name (_DSD, Package () {
> >         ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> >         Package () {
> >           Package (2) { "compatible", "linaro,optee-tz" },
> >           Package (2) { "method", "smc" },
> >         }
> >       })
> >     }
> >
> > which does not require any changes to Linux. So I don't think this patch is needed at all tbh.
>
> Thanks for this example, but actually I failed to trigger kernel optee probe function by using
> above code in ACPI table.
>
> And I am curious how this 'compatible' properties be picked up by kernel when try to match driver in ACPI mode?
>

On SynQuacer,

$ cat /sys/devices/platform/PRP0001:00/firmware_node/modalias
of:Ntos0TClinaro,optee-tz

> My understanding is to get it done by feeding .acpi_match_table with something, right?
>

The PRP0001 HID is handled in a special way. Please grep the Linux
source if you are curious to understand how this is implemented.