Re: [PATCH v4 2/6] arm/virt: Wire up GPIO error source for ACPI / GHES

[Jonathan Cameron]

On Tue, 30 Jul 2024 07:13:30 +0200
Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:

> Em Mon, 29 Jul 2024 17:08:40 +0100
> Jonathan Cameron <Jonathan.Cameron@Huawei.com> escreveu:
> 
> > On Mon, 29 Jul 2024 15:21:06 +0200
> > Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:
> >   
> > > From: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > > 
> > > Creates a Generic Event Device (GED) as specified at    
> > 
> > I wrote this a while back and wasn't aware of the naming
> > mess around GED in the ACPI spec.  This one is just
> > referred to as 'error device' whereas there is also
> > a Generic Event Device.
> > 
> > Linux solved this clash by going with Hardware Error Device
> > I think we should do the same here.  
> 
> I opted to do it a little bit different to stay closer to ACPI 6.5
> 18.3.2.7.2. - Event Notification For Generic Error Sources.
> 
> There, it is actually talking about a General Purpose Event (GPE).
> Current ACPI spec doesn't mention "GED", so maybe such term was fixed
> on some previous ACPI spec revision.
> 
> Basically, it currently mentions:
>       - error device
>       - GPE / General Purpose Event
>       - Generic Hardware Error Source Structure 
> 
> I guess Linux crafted the term Hardware Error device by mixing
> those.
> 
> As we don't need to really preserve such names here, as this appears
> only at the patch description, I opted to rewrite the patch description
> to:
> 
>     arm/virt: Wire up GPIO error source for ACPI / GHES
>     
>     Creates a hardware event device to support General Purpose
>     Event (GPE) as specified at ACPI 6.5 specification at 18.3.2.7.2:
>     
> https://uefi.org/specs/ACPI/6.5/18_Platform_Error_Interfaces.html#event-notification-for-generic-error-sources
>     using HID PNP0C33.
>     
>     The PNP0C33 device is used to report hardware errors to
>     the bios via ACPI APEI Generic Hardware Error Source (GHES).
>     
>     It is aligned with Linux Kernel patch:
>     
> https://lore.kernel.org/lkml/1272350481-27951-8-git-send-email-ying.huang@intel.com/
>     
>     [mchehab: use a define for the generic event pin number and do some 
> cleanups]
>     Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>     Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> 
> Clearly associating "hardware event device" with ACPI GPE. That sounds
> good enough to be stored at the git description associated with such
> change.
All looks good to me.

Thanks,

Jonathan

> 
> > > ACPI 6.5 specification at 18.3.2.7.2:
> > > https://uefi.org/specs/ACPI/6.5/18_Platform_Error_Interfaces.html#event-notification-for-generic-error-sources
> > > with HID PNP0C33.
> > > 
> > > The PNP0C33 device is used to report hardware errors to
> > > the bios via ACPI APEI Generic Hardware Error Source (GHES).
> > > 
> > > It is aligned with Linux Kernel patch:
> > > https://lore.kernel.org/lkml/1272350481-27951-8-git-send-email-ying.huang@intel.com/
> > > 
> > > [mchehab: use a define for the generic event pin number and do some 
> > > cleanups]
> > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>    
> >   
> > > ---
> > >  hw/arm/virt-acpi-build.c | 30 ++++++++++++++++++++++++++----
> > >  hw/arm/virt.c            | 14 ++++++++++++--
> > >  include/hw/arm/virt.h    |  1 +
> > >  include/hw/boards.h      |  1 +
> > >  4 files changed, 40 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> > > index f76fb117adff..c502ccf40909 100644
> > > --- a/hw/arm/virt-acpi-build.c
> > > +++ b/hw/arm/virt-acpi-build.c
> > > @@ -63,6 +63,7 @@
> > >  
> > >  #define ARM_SPI_BASE 32
> > >  
> > > +#define ACPI_GENERIC_EVENT_DEVICE "GEDD"    
> > 
> > Ah. My mistake. This is the confusing named GENERIC_ERROR_DEVICE
> > or HARDWARE_ERROR_DEVICE (which is what Linux called it because
> > in the ACPI Spec it is just (all lower case) error device).  
> 
> I opted to use a different name there, using just error device,
> together with the name of the PNP device. So:
> 
>       #define PNP0C33_ERROR_DEVICE "GEDD"
> 
> This is clear enough for people just looking at the driver, and
> even clearer for people familiar with session 18.3.2.7.2 of the
> ACPI spec.
> 
> >   
> > >  #define ACPI_BUILD_TABLE_SIZE             0x20000    
> >   
> > >  /* DSDT */
> > >  static void
> > >  build_dsdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
> > > @@ -841,10 +863,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, 
> > > VirtMachineState *vms)
> > >                        HOTPLUG_HANDLER(vms->acpi_dev),
> > >                        irqmap[VIRT_ACPI_GED] + ARM_SPI_BASE, 
> > > AML_SYSTEM_MEMORY,
> > >                        memmap[VIRT_ACPI_GED].base);
> > > -    } else {
> > > -        acpi_dsdt_add_gpio(scope, &memmap[VIRT_GPIO],
> > > -                           (irqmap[VIRT_GPIO] + ARM_SPI_BASE));
> > >      }
> > > +    acpi_dsdt_add_gpio(scope, &memmap[VIRT_GPIO],
> > > +                       (irqmap[VIRT_GPIO] + ARM_SPI_BASE));    
> > 
> > Arguably excess brackets, but obviously this is just a code move
> > so fine to keep it the same.  
> 
> I'll drop the extra brackets.
> 
> > >  
> > >      if (vms->acpi_dev) {
> > >          uint32_t event = object_property_get_uint(OBJECT(vms->acpi_dev),
> > > @@ -858,6 +879,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker, 
> > > VirtMachineState *vms)
> > >      }
> > >  
> > >      acpi_dsdt_add_power_button(scope);  
> 
> > > +    acpi_dsdt_add_generic_event_device(scope);  
> 
> I'm also renaming this function/function call to run away from GED,
> calling it as:
> 
>        acpi_dsdt_add_error_device(scope);
> 
> > >  #ifdef CONFIG_TPM
> > >      acpi_dsdt_add_tpm(scope, vms);
> > >  #endif    
> >   
> 
> Thanks,
> Mauro