usbfs: Add support for allocating / freeing streams

This allows userspace to use bulk-streams, just like in kernel drivers, see
Documentation/usb/bulk-streams.txt for details on the in kernel API. This
is exported pretty much one on one to userspace.

To use streams an app must first make a USBDEVFS_ALLOC_STREAMS ioctl,
on success this will return the number of streams available (which may be
less then requested). If there are n streams the app can then submit
usbdevfs_urb-s with their stream_id member set to 1-n to use a specific
stream. IE if USBDEVFS_ALLOC_STREAMS returns 4 then stream_id 1-4 can be
used.

When the app is done using streams it should call USBDEVFS_FREE_STREAMS

Note applications are advised to use libusb rather then using the
usbdevfs api directly. The latest version of libusb has support for streams.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>

1 files changed, 118 insertions, 0 deletions

diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c
index 502974b4deb5..12401ee4ba0e 100644
--- a/drivers/usb/core/devio.c
+++ b/drivers/usb/core/devio.c
@@ -778,6 +778,79 @@ static struct usb_host_endpoint *ep_to_host_endpoint(struct usb_device *dev,
                 return dev->ep_out[ep & USB_ENDPOINT_NUMBER_MASK];
 }
 
+static int parse_usbdevfs_streams(struct dev_state *ps,
+                                  struct usbdevfs_streams __user *streams,
+                                  unsigned int *num_streams_ret,
+                                  unsigned int *num_eps_ret,
+                                  struct usb_host_endpoint ***eps_ret,
+                                  struct usb_interface **intf_ret)
+{
+        unsigned int i, num_streams, num_eps;
+        struct usb_host_endpoint **eps;
+        struct usb_interface *intf = NULL;
+        unsigned char ep;
+        int ifnum, ret;
+
+        if (get_user(num_streams, &streams->num_streams) ||
+            get_user(num_eps, &streams->num_eps))
+                return -EFAULT;
+
+        if (num_eps < 1 || num_eps > USB_MAXENDPOINTS)
+                return -EINVAL;
+
+        /* The XHCI controller allows max 2 ^ 16 streams */
+        if (num_streams_ret && (num_streams < 2 || num_streams > 65536))
+                return -EINVAL;
+
+        eps = kmalloc(num_eps * sizeof(*eps), GFP_KERNEL);
+        if (!eps)
+                return -ENOMEM;
+
+        for (i = 0; i < num_eps; i++) {
+                if (get_user(ep, &streams->eps[i])) {
+                        ret = -EFAULT;
+                        goto error;
+                }
+                eps[i] = ep_to_host_endpoint(ps->dev, ep);
+                if (!eps[i]) {
+                        ret = -EINVAL;
+                        goto error;
+                }
+
+                /* usb_alloc/free_streams operate on an usb_interface */
+                ifnum = findintfep(ps->dev, ep);
+                if (ifnum < 0) {
+                        ret = ifnum;
+                        goto error;
+                }
+
+                if (i == 0) {
+                        ret = checkintf(ps, ifnum);
+                        if (ret < 0)
+                                goto error;
+                        intf = usb_ifnum_to_if(ps->dev, ifnum);
+                } else {
+                        /* Verify all eps belong to the same interface */
+                        if (ifnum != intf->altsetting->desc.bInterfaceNumber) {
+                                ret = -EINVAL;
+                                goto error;
+                        }
+                }
+        }
+
+        if (num_streams_ret)
+                *num_streams_ret = num_streams;
+        *num_eps_ret = num_eps;
+        *eps_ret = eps;
+        *intf_ret = intf;
+
+        return 0;
+
+error:
+        kfree(eps);
+        return ret;
+}
+
 static int match_devt(struct device *dev, void *data)
 {
         return dev->devt == (dev_t) (unsigned long) data;
@@ -2009,6 +2082,45 @@ static int proc_disconnect_claim(struct dev_state *ps, void __user *arg)
         return claimintf(ps, dc.interface);
 }
 
+static int proc_alloc_streams(struct dev_state *ps, void __user *arg)
+{
+        unsigned num_streams, num_eps;
+        struct usb_host_endpoint **eps;
+        struct usb_interface *intf;
+        int r;
+
+        r = parse_usbdevfs_streams(ps, arg, &num_streams, &num_eps,
+                                   &eps, &intf);
+        if (r)
+                return r;
+
+        destroy_async_on_interface(ps,
+                                   intf->altsetting[0].desc.bInterfaceNumber);
+
+        r = usb_alloc_streams(intf, eps, num_eps, num_streams, GFP_KERNEL);
+        kfree(eps);
+        return r;
+}
+
+static int proc_free_streams(struct dev_state *ps, void __user *arg)
+{
+        unsigned num_eps;
+        struct usb_host_endpoint **eps;
+        struct usb_interface *intf;
+        int r;
+
+        r = parse_usbdevfs_streams(ps, arg, NULL, &num_eps, &eps, &intf);
+        if (r)
+                return r;
+
+        destroy_async_on_interface(ps,
+                                   intf->altsetting[0].desc.bInterfaceNumber);
+
+        r = usb_free_streams(intf, eps, num_eps, GFP_KERNEL);
+        kfree(eps);
+        return r;
+}
+
 /*
  * NOTE:  All requests here that have interface numbers as parameters
  * are assuming that somehow the configuration has been prevented from
@@ -2185,6 +2297,12 @@ static long usbdev_do_ioctl(struct file *file, unsigned int cmd,
         case USBDEVFS_DISCONNECT_CLAIM:
                 ret = proc_disconnect_claim(ps, p);
                 break;
+        case USBDEVFS_ALLOC_STREAMS:
+                ret = proc_alloc_streams(ps, p);
+                break;
+        case USBDEVFS_FREE_STREAMS:
+                ret = proc_free_streams(ps, p);
+                break;
         }
         usb_unlock_device(dev);
         if (ret >= 0)