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Subject[PATCH V6 5/8] vfio: platform: call _RST method when using ACPI
Date
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 checks the presence of _RST method and calls the _RST
method when reset is requested.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Reviewed-by: Eric Auger <eric.auger@linaro.org>
---
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);
}

dev_warn(vdev->device, "no reset function found!\n");
--
1.8.2.1
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