On Mon, 13 Jun 2016 00:26:38 -0400
Sinan Kaya <okaya@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxx>
> Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
> ---
> drivers/vfio/platform/vfio_platform_common.c | 51 ++++++++++++++++++++++++++++
> 1 file changed, 51 insertions(+)
>
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index e7ce2c2..0ea8c26 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -73,21 +73,66 @@ static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
> }
> return 0;
> }
> +
> +static int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev,
> + const char **extra_dbg)
> +{
> + struct device *dev = vdev->device;
> + acpi_handle handle = ACPI_HANDLE(dev);
> + acpi_status acpi_ret;
> + unsigned long long val;
> +
> + acpi_ret = acpi_evaluate_integer(handle, "_RST", NULL, &val);
> + if (ACPI_FAILURE(acpi_ret)) {
> + if (extra_dbg)
> + *extra_dbg = acpi_format_exception(acpi_ret);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
> +{
> + struct device *dev = vdev->device;
> + acpi_handle handle = ACPI_HANDLE(dev);
> +
> + return acpi_has_method(handle, "_RST");
> +}
> #else
> static inline int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
> struct device *dev)
> {
> return -ENOENT;
> }
> +
> +static inline
> +int vfio_platform_acpi_call_reset(struct vfio_platform_device *vdev,
> + const char **extra_dbg)
> +{
> + return -ENOENT;
> +}
> +
> +static inline
> +bool vfio_platform_acpi_has_reset(struct vfio_platform_device *vdev)
> +{
> + return false;
> +}
> #endif
>
> static bool vfio_platform_has_reset(struct vfio_platform_device *vdev)
> {
> + if (vdev->acpihid)
> + 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 (vdev->acpihid)
> + return;
> +
> vdev->of_reset = vfio_platform_lookup_reset(vdev->compat,
> &vdev->reset_module);
> if (!vdev->of_reset) {
> @@ -99,6 +144,9 @@ static void vfio_platform_get_reset(struct vfio_platform_device *vdev)
>
> static void vfio_platform_put_reset(struct vfio_platform_device *vdev)
> {
> + if (vdev->acpihid)
> + return;
> +
> if (vdev->of_reset)
> module_put(vdev->reset_module);
> }
> @@ -177,6 +225,9 @@ static int vfio_platform_call_reset(struct vfio_platform_device *vdev,
> if (vdev->of_reset) {
> dev_info(vdev->device, "reset\n");
> return vdev->of_reset(vdev);
> + } else if (vdev->acpihid) {
> + dev_info(vdev->device, "reset\n");
> + return vfio_platform_acpi_call_reset(vdev, extra_dbg);
nit, all the cases until this one prioritize ACPI over DT, here we have
the opposite. Granted we should never have of_reset set when acpihid
is set. A macro like
#define vfio_platform_is_acpi(vdev) (vdev->acpihid != NULL)
might be useful.
> }
>
> dev_warn(vdev->device, "no reset function found!\n");
--
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