[RFC 1/3] VFIO: platform: add reset support

[Eric Auger]

This patch adds support for vfio platform reset. The modality only is
exposed when a specialized VFIO driver populates the reset callback.
For the generic vfio platform/amba driver, the modality is not supported
since the driver is by essence a metadriver and does not know how to
reset the underlying device.

Signed-off-by: Eric Auger <eric.auger at linaro.org>
---
 drivers/vfio/platform/vfio_platform_common.c  | 12 ++++++++++--
 drivers/vfio/platform/vfio_platform_private.h |  1 +
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 4113d46..b989ce5 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -100,6 +100,8 @@ static void vfio_platform_release(void *device_data)
 	mutex_lock(&driver_lock);
 
 	if (!(--vdev->refcnt)) {
+		if (vdev->reset)
+			vdev->reset(vdev);
 		vfio_platform_regions_cleanup(vdev);
 		vfio_platform_irq_cleanup(vdev);
 	}
@@ -159,6 +161,8 @@ static long vfio_platform_ioctl(void *device_data,
 		if (info.argsz < minsz)
 			return -EINVAL;
 
+		if (vdev->reset)
+			vdev->flags |= VFIO_DEVICE_FLAGS_RESET;
 		info.flags = vdev->flags;
 		info.num_regions = vdev->num_regions;
 		info.num_irqs = vdev->num_irqs;
@@ -252,8 +256,12 @@ static long vfio_platform_ioctl(void *device_data,
 
 		return ret;
 
-	} else if (cmd == VFIO_DEVICE_RESET)
-		return -EINVAL;
+	} else if (cmd == VFIO_DEVICE_RESET) {
+		if (vdev->reset)
+			return vdev->reset(vdev);
+		else
+			return -ENOTTY;
+	}
 
 	return -ENOTTY;
 }
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index 253caa3..0a20028 100644
--- a/drivers/vfio/platform/vfio_platform_private.h
+++ b/drivers/vfio/platform/vfio_platform_private.h
@@ -68,6 +68,7 @@ struct vfio_platform_device {
 	struct resource*
 		(*get_resource)(struct vfio_platform_device *vdev, int i);
 	int	(*get_irq)(struct vfio_platform_device *vdev, int i);
+	int	(*reset)(struct vfio_platform_device *vdev);
 };
 
 extern int vfio_platform_probe_common(struct vfio_platform_device *vdev,
-- 
1.9.1