[RFC 5/9] VFIO: Extend external user API

[Eric Auger]

New functions are added to be called from ARM KVM-VFIO device.

- vfio_device_get_external_user enables to get a vfio device from
  its fd
- vfio_device_put_external_user puts the vfio device
- vfio_external_get_type enables to retrieve the type of the device
  (PCI or platform)
- vfio_external_get_base_device enables to get the
  struct device*, useful to access the platform_device

Signed-off-by: Eric Auger <eric.auger at linaro.org>
---
 drivers/vfio/vfio.c  | 35 +++++++++++++++++++++++++++++++++++
 include/linux/vfio.h |  4 ++++
 2 files changed, 39 insertions(+)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 8e84471..c93b9e4 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1401,6 +1401,41 @@ void vfio_group_put_external_user(struct vfio_group *group)
 }
 EXPORT_SYMBOL_GPL(vfio_group_put_external_user);
 
+struct vfio_device *vfio_device_get_external_user(struct file *filep)
+{
+	struct vfio_device *vdev = filep->private_data;
+
+	if (filep->f_op != &vfio_device_fops)
+		return ERR_PTR(-EINVAL);
+
+	vfio_device_get(vdev);
+	return vdev;
+}
+EXPORT_SYMBOL_GPL(vfio_device_get_external_user);
+
+void vfio_device_put_external_user(struct vfio_device *vdev)
+{
+	vfio_device_put(vdev);
+}
+EXPORT_SYMBOL_GPL(vfio_device_put_external_user);
+
+int vfio_external_get_type(struct vfio_device *vdev)
+{
+	if (!strcmp(vdev->ops->name,  "vfio-platform"))
+		return VFIO_DEVICE_FLAGS_PLATFORM;
+	else if (!strcmp(vdev->ops->name,  "vfio-pci"))
+		return VFIO_DEVICE_FLAGS_PCI;
+	else
+		return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(vfio_external_get_type);
+
+struct device *vfio_external_get_base_device(struct vfio_device *vdev)
+{
+	return vdev->dev;
+}
+EXPORT_SYMBOL_GPL(vfio_external_get_base_device);
+
 int vfio_external_user_iommu_id(struct vfio_group *group)
 {
 	return iommu_group_id(group->iommu_group);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index ffe04ed..19e98eb 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -99,6 +99,10 @@ extern void vfio_group_put_external_user(struct vfio_group *group);
 extern int vfio_external_user_iommu_id(struct vfio_group *group);
 extern long vfio_external_check_extension(struct vfio_group *group,
 					  unsigned long arg);
+extern struct vfio_device *vfio_device_get_external_user(struct file *filep);
+extern void vfio_device_put_external_user(struct vfio_device *vdev);
+extern int vfio_external_get_type(struct vfio_device *vdev);
+extern struct device *vfio_external_get_base_device(struct vfio_device *vdev);
 
 struct pci_dev;
 #ifdef CONFIG_EEH
-- 
1.9.1