From Eric Anholt:

 Introduce a new ioctl, DRM_IOCTL_SET_VERSION. This ioctl allows the server
or client to notify the DRM that it expects a certain version of the device
dependent or device independent interface. If the major doesn't match or minor
is too large, EINVAL is returned. A major of -1 means that the requestor
doesn't care about that portion of the interface. The ioctl returns the actual
versions in the same struct. 

drivers/char/drm/drm.h

@@ -580,6 +580,16 @@ typedef struct drm_scatter_gather {
 	unsigned long handle;	/**< Used for mapping / unmapping */
 } drm_scatter_gather_t;
 
+/**
+ * DRM_IOCTL_SET_VERSION ioctl argument type.
+ */
+typedef struct drm_set_version {
+	int drm_di_major;
+	int drm_di_minor;
+	int drm_dd_major;
+	int drm_dd_minor;
+} drm_set_version_t;
+
 
 #define DRM_IOCTL_BASE			'd'
 #define DRM_IO(nr)			_IO(DRM_IOCTL_BASE,nr)
@@ -594,6 +604,7 @@ typedef struct drm_scatter_gather {
 #define DRM_IOCTL_GET_MAP               DRM_IOWR(0x04, drm_map_t)
 #define DRM_IOCTL_GET_CLIENT            DRM_IOWR(0x05, drm_client_t)
 #define DRM_IOCTL_GET_STATS             DRM_IOR( 0x06, drm_stats_t)
+#define DRM_IOCTL_SET_VERSION		DRM_IOWR(0x07, drm_set_version_t)
 
 #define DRM_IOCTL_SET_UNIQUE		DRM_IOW( 0x10, drm_unique_t)
 #define DRM_IOCTL_AUTH_MAGIC		DRM_IOW( 0x11, drm_auth_t)

drivers/char/drm/drmP.h

@@ -819,6 +819,8 @@ extern int	     DRM(getclient)(struct inode *inode, struct file *filp,
 				    unsigned int cmd, unsigned long arg);
 extern int	     DRM(getstats)(struct inode *inode, struct file *filp,
 				   unsigned int cmd, unsigned long arg);
+extern int	     DRM(setversion)(struct inode *inode, struct file *filp,
+				     unsigned int cmd, unsigned long arg);
 
 				/* Context IOCTL support (drm_context.h) */
 extern int	     DRM(resctx)( struct inode *inode, struct file *filp,

drivers/char/drm/drm_drv.h

@@ -174,6 +174,7 @@ static drm_ioctl_desc_t		  DRM(ioctls)[] = {
 	[DRM_IOCTL_NR(DRM_IOCTL_GET_MAP)]       = { DRM(getmap),      0, 0 },
 	[DRM_IOCTL_NR(DRM_IOCTL_GET_CLIENT)]    = { DRM(getclient),   0, 0 },
 	[DRM_IOCTL_NR(DRM_IOCTL_GET_STATS)]     = { DRM(getstats),    0, 0 },
+	[DRM_IOCTL_NR(DRM_IOCTL_SET_VERSION)]   = { DRM(setversion),  0, 1 },
 
 	[DRM_IOCTL_NR(DRM_IOCTL_SET_UNIQUE)]    = { DRM(setunique),   1, 1 },
 	[DRM_IOCTL_NR(DRM_IOCTL_BLOCK)]         = { DRM(noop),        1, 1 },

drivers/char/drm/drm_ioctl.h

@@ -35,6 +35,7 @@
 
 #include "drmP.h"
 
+#include "linux/pci.h"
 
 /**
  * Get interrupt from bus id.
@@ -139,7 +140,9 @@ int DRM(getunique)(struct inode *inode, struct file *filp,
  * \return zero on success or a negative number on failure.
  *
  * Copies the bus id from userspace into drm_device::unique, and searches for
- * the respective PCI device, updating drm_device::pdev.
+ * the respective PCI device, updating drm_device::pdev.  Deprecated in
+ * interface version 1.1 and will return EBUSY when setversion has requested
+ * version 1.1 or greater.
  */
 int DRM(setunique)(struct inode *inode, struct file *filp,
 		   unsigned int cmd, unsigned long arg)
@@ -217,6 +220,36 @@ int DRM(setunique)(struct inode *inode, struct file *filp,
 	return 0;
 }
 
+static int
+DRM(set_busid)(drm_device_t *dev)
+{
+	if (dev->unique != NULL)
+		return EBUSY;
+
+	dev->unique_len = 20;
+	dev->unique = DRM(alloc)(dev->unique_len + 1, DRM_MEM_DRIVER);
+	if (dev->unique == NULL)
+		return ENOMEM;
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,5,74)
+	snprintf(dev->unique, dev->unique_len, "pci:%s", pci_name(dev->pdev));
+#else
+	{
+		int domain = 0;
+#ifdef __alpha__
+		struct pci_controller *hose = pci_dev->sysdata;
+
+		domain = hose->bus->number;
+#endif
+		snprintf(dev->unique, dev->unique_len, "pci:%04x:%02x:%02x.%d",
+			domain, dev->pdev->bus->number,
+			PCI_SLOT(dev->pdev->devfn), PCI_FUNC(dev->pdev->devfn));
+	}
+#endif
+
+	return 0;
+}
+
 
 /**
  * Get a mapping information.
@@ -363,3 +396,43 @@ int DRM(getstats)( struct inode *inode, struct file *filp,
 		return -EFAULT;
 	return 0;
 }
+
+int DRM(setversion)(DRM_IOCTL_ARGS)
+{
+	DRM_DEVICE;
+	drm_set_version_t sv;
+	drm_set_version_t retv;
+
+	DRM_COPY_FROM_USER_IOCTL(sv, (drm_set_version_t *)data, sizeof(sv));
+
+	retv.drm_di_major = 1;
+	retv.drm_di_minor = 1;
+	retv.drm_dd_major = DRIVER_MAJOR;
+	retv.drm_dd_minor = DRIVER_MINOR;
+	
+	DRM_COPY_TO_USER_IOCTL((drm_set_version_t *)data, retv, sizeof(sv));
+
+	if (sv.drm_di_major != -1) {
+		if (sv.drm_di_major != 1 || sv.drm_di_minor < 0)
+			return EINVAL;
+		if (sv.drm_di_minor > 1)
+			return EINVAL;
+		if (sv.drm_di_minor >= 1) {
+			/*
+			 * Version 1.1 includes tying of DRM to specific device
+			 */
+			DRM(set_busid)(dev);
+		}
+	}
+
+	if (sv.drm_dd_major != -1) {
+		if (sv.drm_dd_major != DRIVER_MAJOR || sv.drm_dd_minor < 0)
+			return EINVAL;
+		if (sv.drm_dd_minor > DRIVER_MINOR)
+			return EINVAL;
+#ifdef DRIVER_SETVERSION
+		DRIVER_SETVERSION(dev, sv);
+#endif
+	}
+	return 0;
+}