drm/xe/pci: Introduce a helper to allow VF access to PF xe_device

In certain scenarios (such as VF migration), VF driver needs to interact
with PF driver.
Add a helper to allow VF driver access to PF xe_device.

Reviewed-by: Michal Wajdeczko <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Michał Winiarski <[e-mail]>
(cherry picked from commit 8b3cce3ad9c78ce3dae1c178f99352d50e12a3c0)
Signed-off-by: Thomas Hellström <[e-mail]>

drivers/gpu/drm/xe/xe_pci.c

···
 #endif
 };
 
+/**
+ * xe_pci_to_pf_device() - Get PF &xe_device.
+ * @pdev: the VF &pci_dev device
+ *
+ * Return: pointer to PF &xe_device, NULL otherwise.
+ */
+struct xe_device *xe_pci_to_pf_device(struct pci_dev *pdev)
+{
+	struct drm_device *drm;
+
+	drm = pci_iov_get_pf_drvdata(pdev, &xe_pci_driver);
+	if (IS_ERR(drm))
+		return NULL;
+
+	return to_xe_device(drm);
+}
+
 int xe_register_pci_driver(void)
 {
 	return pci_register_driver(&xe_pci_driver);

drivers/gpu/drm/xe/xe_pci.h

···
 #ifndef _XE_PCI_H_
 #define _XE_PCI_H_
 
+struct pci_dev;
+
 int xe_register_pci_driver(void);
 void xe_unregister_pci_driver(void);
+struct xe_device *xe_pci_to_pf_device(struct pci_dev *pdev);
 
 #endif