[PATCH V10 6/9] vfio: platform: call _RST method when using ACPI

Sinan Kaya
2016-07-18T23:09:45Z

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 | 50 +++++++++++++++++++++++++++-
1 file changed, 49 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index f6025c9..b1e5801 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);

@@ -76,13 +78,53 @@ static int vfio_platform_acpi_probe(struct vfio_platform_device *vdev,
return WARN_ON(!vdev->acpihid) ? -ENOENT : 0;
}

+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
+}
+
+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
+}
+
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) {
@@ -94,6 +136,9 @@ 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);
}
@@ -169,7 +214,10 @@ 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);
}
--
1.8.2.1