[PATCH 3/5] VFIO: platform: add reset callback

[eric.auger@linaro.org (Eric Auger)]

A new reset callback is introduced. If this callback is populated,
the reset is invoked on device release or upon userspace ioctl. The
modality is exposed on VFIO_DEVICE_GET_INFO.

Signed-off-by: Eric Auger <eric.auger@linaro.org>

---

v2 -> v3:
- change patch title and commit message. Use IS_ERR_OR_NULL to
  anticipate for getter returned value.

v1 -> v2:
- On VFIO_DEVICE_RESET returns -EINVAL in case the callback is not
  populated (instead of -ENOTTY)
---
 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 edbf24c..0d10018 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -103,6 +103,8 @@ static void vfio_platform_release(void *device_data)
 	mutex_lock(&driver_lock);
 
 	if (!(--vdev->refcnt)) {
+		if (!IS_ERR_OR_NULL(vdev->reset))
+			vdev->reset(vdev);
 		vfio_platform_regions_cleanup(vdev);
 		vfio_platform_irq_cleanup(vdev);
 	}
@@ -162,6 +164,8 @@ static long vfio_platform_ioctl(void *device_data,
 		if (info.argsz < minsz)
 			return -EINVAL;
 
+		if (!IS_ERR_OR_NULL(vdev->reset))
+			vdev->flags |= VFIO_DEVICE_FLAGS_RESET;
 		info.flags = vdev->flags;
 		info.num_regions = vdev->num_regions;
 		info.num_irqs = vdev->num_irqs;
@@ -255,8 +259,12 @@ 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 (!IS_ERR_OR_NULL(vdev->reset))
+			return vdev->reset(vdev);
+		else
+			return -EINVAL;
+	}
 
 	return -ENOTTY;
 }
diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
index 68909a4..84ccf6d 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 {
 		(*get_resource)(struct vfio_platform_device *vdev, int i);
 	int	(*get_irq)(struct vfio_platform_device *vdev, int i);
 	struct device *(*get_device)(struct vfio_platform_device *vdev);
+	int	(*reset)(struct vfio_platform_device *vdev);
 };
 
 typedef int (*vfio_platform_reset_fn_t)(struct vfio_platform_device *vdev);
-- 
1.9.1