Re: [PATCH v3 1/2] platform/x86: surfacepro3_button: Fix device check

[Andy Shevchenko <andy.shevchenko@gmail.com>]

On Sat, Jul 20, 2019 at 6:05 PM Maximilian Luz <luzmaximilian@gmail.com> wrote:
>
> Do not use the surfacepro3_button driver on newer Microsoft Surface
> models, only use it on the Surface Pro 3 and 4. Newer models (5th, 6th
> and possibly future generations) use the same device as the Surface Pro
> 4 to represent their volume and power buttons (MSHW0040), but their
> actual implementation is significantly different. This patch ensures
> that the surfacepro3_button driver is only used on the Pro 3 and 4
> models, allowing a different driver to bind on other models.
>

Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>

assuming it will go thru Input subsystem.

> Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
> ---
>  drivers/platform/x86/surfacepro3_button.c | 47 +++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
>
> diff --git a/drivers/platform/x86/surfacepro3_button.c b/drivers/platform/x86/surfacepro3_button.c
> index 47c6d000465a..ec515223f654 100644
> --- a/drivers/platform/x86/surfacepro3_button.c
> +++ b/drivers/platform/x86/surfacepro3_button.c
> @@ -20,6 +20,12 @@
>  #define SURFACE_BUTTON_OBJ_NAME                "VGBI"
>  #define SURFACE_BUTTON_DEVICE_NAME     "Surface Pro 3/4 Buttons"
>
> +#define MSHW0040_DSM_REVISION          0x01
> +#define MSHW0040_DSM_GET_OMPR          0x02    // get OEM Platform Revision
> +static const guid_t MSHW0040_DSM_UUID =
> +       GUID_INIT(0x6fd05c69, 0xcde3, 0x49f4, 0x95, 0xed, 0xab, 0x16, 0x65,
> +                 0x49, 0x80, 0x35);
> +
>  #define SURFACE_BUTTON_NOTIFY_TABLET_MODE      0xc8
>
>  #define SURFACE_BUTTON_NOTIFY_PRESS_POWER      0xc6
> @@ -142,6 +148,44 @@ static int surface_button_resume(struct device *dev)
>  }
>  #endif
>
> +/*
> + * Surface Pro 4 and Surface Book 2 / Surface Pro 2017 use the same device
> + * ID (MSHW0040) for the power/volume buttons. Make sure this is the right
> + * device by checking for the _DSM method and OEM Platform Revision.
> + *
> + * Returns true if the driver should bind to this device, i.e. the device is
> + * either MSWH0028 (Pro 3) or MSHW0040 on a Pro 4 or Book 1.
> + */
> +static bool surface_button_check_MSHW0040(struct acpi_device *dev)
> +{
> +       acpi_handle handle = dev->handle;
> +       union acpi_object *result;
> +       u64 oem_platform_rev = 0;       // valid revisions are nonzero
> +
> +       // get OEM platform revision
> +       result = acpi_evaluate_dsm_typed(handle, &MSHW0040_DSM_UUID,
> +                                        MSHW0040_DSM_REVISION,
> +                                        MSHW0040_DSM_GET_OMPR,
> +                                        NULL, ACPI_TYPE_INTEGER);
> +
> +       /*
> +        * If evaluating the _DSM fails, the method is not present. This means
> +        * that we have either MSHW0028 or MSHW0040 on Pro 4 or Book 1, so we
> +        * should use this driver. We use revision 0 indicating it is
> +        * unavailable.
> +        */
> +
> +       if (result) {
> +               oem_platform_rev = result->integer.value;
> +               ACPI_FREE(result);
> +       }
> +
> +       dev_dbg(&dev->dev, "OEM Platform Revision %llu\n", oem_platform_rev);
> +
> +       return oem_platform_rev == 0;
> +}
> +
> +
>  static int surface_button_add(struct acpi_device *device)
>  {
>         struct surface_button *button;
> @@ -154,6 +198,9 @@ static int surface_button_add(struct acpi_device *device)
>             strlen(SURFACE_BUTTON_OBJ_NAME)))
>                 return -ENODEV;
>
> +       if (!surface_button_check_MSHW0040(device))
> +               return -ENODEV;
> +
>         button = kzalloc(sizeof(struct surface_button), GFP_KERNEL);
>         if (!button)
>                 return -ENOMEM;
> --
> 2.22.0
>


-- 
With Best Regards,
Andy Shevchenko