+/**
+ * File \c open operation.
+ *
+ * \param inode device inode.
+ * \param filp file pointer.
+ *
+ * Puts the dev->fops corresponding to the device minor number into
+ * \p filp, call the \c open method, and restore the file operations.
+ */
+int drm_stub_open(struct inode *inode, struct file *filp)
+{
+ drm_device_t *dev = NULL;
+ int minor = iminor(inode);
+ int err = -ENODEV;
+ const struct file_operations *old_fops;
+
+ DRM_DEBUG("\n");
+
+ if (!((minor >= 0) && (minor < drm_cards_limit)))
+ return -ENODEV;
+
+ if (!drm_heads[minor])
+ return -ENODEV;
+
+ if (!(dev = drm_heads[minor]->dev))
+ return -ENODEV;
+
+ old_fops = filp->f_op;
+ filp->f_op = fops_get(&dev->driver->fops);
+ if (filp->f_op->open && (err = filp->f_op->open(inode, filp))) {
+ fops_put(filp->f_op);
+ filp->f_op = fops_get(old_fops);
+ }
+ fops_put(old_fops);
+
+ return err;
+}
+
+/**
+ * Check whether DRI will run on this CPU.
+ *
+ * \return non-zero if the DRI will run on this CPU, or zero otherwise.
+ */
+static int drm_cpu_valid(void)
+{
+#if defined(__i386__)
+ if (boot_cpu_data.x86 == 3)
+ return 0; /* No cmpxchg on a 386 */
+#endif
+#if defined(__sparc__) && !defined(__sparc_v9__)
+ return 0; /* No cmpxchg before v9 sparc. */
+#endif
+ return 1;
+}
+
+/**
+ * Called whenever a process opens /dev/drm.
+ *
+ * \param inode device inode.
+ * \param filp file pointer.
+ * \param dev device.
+ * \return zero on success or a negative number on failure.
+ *
+ * Creates and initializes a drm_file structure for the file private data in \p
+ * filp and add it into the double linked list in \p dev.
+ */
+static int drm_open_helper(struct inode *inode, struct file *filp,
+ drm_device_t * dev)
+{
+ int minor = iminor(inode);
+ drm_file_t *priv;
+ int ret;
+
+ if (filp->f_flags & O_EXCL)
+ return -EBUSY; /* No exclusive opens */
+ if (!drm_cpu_valid())
+ return -EINVAL;
+
+ DRM_DEBUG("pid = %d, minor = %d\n", current->pid, minor);
+
+ priv = drm_alloc(sizeof(*priv), DRM_MEM_FILES);
+ if (!priv)
+ return -ENOMEM;
+
+ memset(priv, 0, sizeof(*priv));
+ filp->private_data = priv;
+ priv->uid = current->euid;
+ priv->pid = current->pid;
+ priv->minor = minor;
+ priv->head = drm_heads[minor];
+ priv->ioctl_count = 0;
+ /* for compatibility root is always authenticated */
+ priv->authenticated = capable(CAP_SYS_ADMIN);
+ priv->lock_count = 0;
+
+ if (dev->driver->open) {
+ ret = dev->driver->open(dev, priv);
+ if (ret < 0)
+ goto out_free;
+ }
+
+ mutex_lock(&dev->struct_mutex);
+ if (!dev->file_last) {
+ priv->next = NULL;
+ priv->prev = NULL;
+ dev->file_first = priv;
+ dev->file_last = priv;
+ /* first opener automatically becomes master */
+ priv->master = 1;
+ } else {
+ priv->next = NULL;
+ priv->prev = dev->file_last;
+ dev->file_last->next = priv;
+ dev->file_last = priv;
+ }
+ mutex_unlock(&dev->struct_mutex);
+
+#ifdef __alpha__
+ /*
+ * Default the hose
+ */
+ if (!dev->hose) {
+ struct pci_dev *pci_dev;
+ pci_dev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, NULL);
+ if (pci_dev) {
+ dev->hose = pci_dev->sysdata;
+ pci_dev_put(pci_dev);
+ }
+ if (!dev->hose) {
+ struct pci_bus *b = pci_bus_b(pci_root_buses.next);
+ if (b)
+ dev->hose = b->sysdata;
+ }
+ }
+#endif
+
+ return 0;
+ out_free:
+ drm_free(priv, sizeof(*priv), DRM_MEM_FILES);
+ filp->private_data = NULL;
+ return ret;
+}
+
+/** No-op. */
+int drm_fasync(int fd, struct file *filp, int on)
+{
+ drm_file_t *priv = filp->private_data;
+ drm_device_t *dev = priv->head->dev;
+ int retcode;
+
+ DRM_DEBUG("fd = %d, device = 0x%lx\n", fd,
+ (long)old_encode_dev(priv->head->device));
+ retcode = fasync_helper(fd, filp, on, &dev->buf_async);
+ if (retcode < 0)
+ return retcode;
+ return 0;
+}
+EXPORT_SYMBOL(drm_fasync);
+