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SubjectRe: [PATCH V9 6/9] vfio: platform: call _RST method when using ACPI
On Wed, 13 Jul 2016 22:06:32 -0400
Sinan Kaya <okaya@codeaurora.org> wrote:

> The device tree code checks for the presence of a reset driver and calls
> the of_reset function pointer by looking up the reset driver as a module.
>
> ACPI defines _RST method to perform device level reset. After the _RST
> method is executed, the OS can resume using the device. _RST method is
> expected to stop DMA transfers and IRQs.
>
> This patch introduces two functions as vfio_platform_acpi_has_reset and
> vfio_platform_acpi_call_reset. The has reset method is used to declare
> reset capability via the ioctl flag VFIO_DEVICE_FLAGS_RESET. The call
> reset function is used to execute the _RST ACPI method.
>
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
> drivers/vfio/platform/vfio_platform_common.c | 52 +++++++++++++++++++++++++++-
> 1 file changed, 51 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index 03483c2..2d9c905 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -28,6 +28,8 @@
> #define DRIVER_AUTHOR "Antonios Motakis <a.motakis@virtualopensystems.com>"
> #define DRIVER_DESC "VFIO platform base module"
>
> +#define VFIO_PLATFORM_IS_ACPI(vdev) ((vdev)->acpihid != NULL)
> +
> static LIST_HEAD(reset_list);
> static DEFINE_MUTEX(driver_lock);
>
> @@ -77,13 +79,55 @@ static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
> #endif
> }
>
> +static inline
> +int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev,
> + const char **extra_dbg)
> +{
> +#ifdef CONFIG_ACPI
> + struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
> + struct device *dev = vdev->device;
> + acpi_handle handle = ACPI_HANDLE(dev);
> + acpi_status acpi_ret;
> +
> + acpi_ret = acpi_evaluate_object(handle, "_RST", NULL, &buffer);
> + if (ACPI_FAILURE(acpi_ret)) {
> + if (extra_dbg)
> + *extra_dbg = acpi_format_exception(acpi_ret);
> + return -EINVAL;
> + }
> +
> + return 0;
> +#else
> + return -ENOENT;
> +#endif
> +}
> +
> +static inline
> +bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
> +{
> +#ifdef CONFIG_ACPI
> + struct device *dev = vdev->device;
> + acpi_handle handle = ACPI_HANDLE(dev);
> +
> + return acpi_has_method(handle, "_RST");
> +#else
> + return false;
> +#endif
> +}

What exactly is the rationale for making these inline? Clearly reset
is not a performance relevant path. Thanks,

Alex

> +
> static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
> {
> + if (VFIO_PLATFORM_IS_ACPI(vdev))
> + return vfio_platform_acpi_has_reset(vdev);
> +
> return vdev->of_reset ? true : false;
> }
>
> static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
> {
> + if (VFIO_PLATFORM_IS_ACPI(vdev))
> + return;
> +
> vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
> &vdev->reset_module);
> if (!vdev->of_reset) {
> @@ -95,6 +139,9 @@ static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
>
> static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
> {
> + if (VFIO_PLATFORM_IS_ACPI(vdev))
> + return;
> +
> if (vdev->of_reset)
> module_put(vdev->reset_module);
> }
> @@ -170,7 +217,10 @@ static void vfio_platform_regions_cleanup(struct vfio_platform_device *vdev)
> static int vfio_platform_call_reset(struct vfio_platform_device *vdev,
> const char **extra_dbg)
> {
> - if (vdev->of_reset) {
> + if (VFIO_PLATFORM_IS_ACPI(vdev)) {
> + dev_info(vdev->device, "reset\n");
> + return vfio_platform_acpi_call_reset(vdev, extra_dbg);
> + } else if (vdev->of_reset) {
> dev_info(vdev->device, "reset\n");
> return vdev->of_reset(vdev);
> }

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