[PATCH] USB: usbcore misc cleanup (notably for non-dma hcds)

The support for non-dma HCDs is likely the most interesting bit here.

    - makes dma calls behave sensibly when used with host controllers
      that don't use dma (including sl811).  usb_buffer_map() is a nop
      while scatterlist dma mappings fail (as they must).

    - make usb_sg_init() behave sensibly when used with non-dma hcs.
      the urbs are initted with transfer_buffer, not transfer_dma.
      this is the higher level analogue to usb_buffer_map(), so it
      needs to succeed unless there's a Real Error (tm).

    - moves two compatibility inlines from ehci.h into hcd.h so
      it'll be more practical to have the other hcds work in other
      environments (notably lk 2.4) too

    - remove URB_TIMEOUT_KILLED flag ... no device driver tests it;
      hcds don't really (uhci sets it, never reads it; sl811 doesn't
      enable the path that might set it), and it's not well defined.
      if any hcd needs such state, keep it in hc-private storage.

    - in usb_sg_wait(), use yield() instead of schedule() to let
      other activities free resources needed to continue.  (This
      was noted recently by Oliver.)

drivers/usb/core/hcd.c

@@ -1029,8 +1029,11 @@ static int hcd_submit_urb (struct urb *urb, int mem_flags)
 		return status;
 	}
 
-	/* lower level hcd code should use *_dma exclusively */
-	if (!(urb->transfer_flags & URB_NO_DMA_MAP)) {
+	/* lower level hcd code should use *_dma exclusively,
+	 * unless it uses pio or talks to another transport.
+	 */
+	if (!(urb->transfer_flags & URB_NO_DMA_MAP)
+			&& hcd->controller->dma_mask) {
 		if (usb_pipecontrol (urb->pipe))
 			urb->setup_dma = dma_map_single (
 					hcd->controller,

drivers/usb/core/hcd.h

@@ -111,6 +111,13 @@ struct usb_hcd {	/* usb_bus.hcpriv points to this */
 	 */
 };
 
+/* 2.4 does this a bit differently ... */
+static inline struct usb_bus *hcd_to_bus (struct usb_hcd *hcd)
+{
+	return &hcd->self;
+}
+
+
 struct hcd_dev {	/* usb_device.hcpriv points to this */
 	struct list_head	dev_list;	/* on this hcd */
 	struct list_head	urb_list;	/* pending on this dev */
@@ -343,6 +350,13 @@ extern void usb_deregister_bus (struct usb_bus *);
 extern int usb_register_root_hub (struct usb_device *usb_dev,
 		struct device *parent_dev);
 
+/* for portability to 2.4, hcds should call this */
+static inline int hcd_register_root (struct usb_hcd *hcd)
+{
+	return usb_register_root_hub (
+		hcd_to_bus (hcd)->root_hub, hcd->controller);
+}
+
 /*-------------------------------------------------------------------------*/
 
 /* exported only within usbcore */

drivers/usb/core/message.c

@@ -206,6 +206,7 @@ static void sg_clean (struct usb_sg_request *io)
 		kfree (io->urbs);
 		io->urbs = 0;
 	}
+	if (io->dev->dev.dma_mask != 0)
 		usb_buffer_unmap_sg (io->dev, io->pipe, io->sg, io->nents);
 	io->dev = 0;
 }
@@ -301,6 +302,7 @@ int usb_sg_init (
 {
 	int			i;
 	int			urb_flags;
+	int			dma;
 
 	if (!io || !dev || !sg
 			|| usb_pipecontrol (pipe)
@@ -314,8 +316,16 @@ int usb_sg_init (
 	io->sg = sg;
 	io->nents = nents;
 
-	/* initialize all the urbs we'll use */
+	/* not all host controllers use DMA (like the mainstream pci ones);
+	 * they can use PIO (sl811) or be software over another transport.
+	 */
+	dma = (dev->dev.dma_mask == 0);
+	if (dma)
 		io->entries = usb_buffer_map_sg (dev, pipe, sg, nents);
+	else
+		io->entries = nents;
+
+	/* initialize all the urbs we'll use */
 	if (io->entries <= 0)
 		return io->entries;
 
@@ -347,8 +357,17 @@ int usb_sg_init (
 		io->urbs [i]->status = -EINPROGRESS;
 		io->urbs [i]->actual_length = 0;
 
+		if (dma) {
+			/* hc may use _only_ transfer_dma */
 			io->urbs [i]->transfer_dma = sg_dma_address (sg + i);
 			len = sg_dma_len (sg + i);
+		} else {
+			/* hc may use _only_ transfer_buffer */
+			io->urbs [i]->transfer_buffer =
+				page_address (sg [i].page) + sg [i].offset;
+			len = sg [i].length;
+		}
+
 		if (length) {
 			len = min_t (unsigned, len, length);
 			length -= len;
@@ -434,9 +453,7 @@ void usb_sg_wait (struct usb_sg_request *io)
 			retval = 0;
 			i--;
 			// FIXME:  should it usb_sg_cancel() on INTERRUPT?
-			// how about imposing a backoff?
-			set_current_state (TASK_UNINTERRUPTIBLE);
-			schedule ();
+			yield ();
 			break;
 
 			/* no error? continue immediately.

drivers/usb/core/usb.c

@@ -1224,7 +1224,8 @@ void usb_buffer_free (
  *
  * Return value is either null (indicating no buffer could be mapped), or
  * the parameter.  URB_NO_DMA_MAP is added to urb->transfer_flags if the
- * operation succeeds.
+ * operation succeeds.  If the device is connected to this system through
+ * a non-DMA controller, this operation always succeeds.
  *
  * This call would normally be used for an urb which is reused, perhaps
  * as the target of a large periodic transfer, with usb_buffer_dmasync()
@@ -1245,12 +1246,15 @@ struct urb *usb_buffer_map (struct urb *urb)
 			|| !(controller = bus->controller))
 		return 0;
 
+	if (controller->dma_mask) {
 		urb->transfer_dma = dma_map_single (controller,
 			urb->transfer_buffer, urb->transfer_buffer_length,
 			usb_pipein (urb->pipe)
 				? DMA_FROM_DEVICE : DMA_TO_DEVICE);
 	// FIXME generic api broken like pci, can't report errors
 	// if (urb->transfer_dma == DMA_ADDR_INVALID) return 0;
+	} else
+		urb->transfer_dma = ~0;
 	urb->transfer_flags |= URB_NO_DMA_MAP;
 	return urb;
 }
@@ -1271,6 +1275,7 @@ void usb_buffer_dmasync (struct urb *urb)
 			|| !(controller = bus->controller))
 		return;
 
+	if (controller->dma_mask)
 		dma_sync_single (controller,
 			urb->transfer_dma, urb->transfer_buffer_length,
 			usb_pipein (urb->pipe)
@@ -1295,10 +1300,12 @@ void usb_buffer_unmap (struct urb *urb)
 			|| !(controller = bus->controller))
 		return;
 
+	if (controller->dma_mask)
 		dma_unmap_single (controller,
 			urb->transfer_dma, urb->transfer_buffer_length,
 			usb_pipein (urb->pipe)
 				? DMA_FROM_DEVICE : DMA_TO_DEVICE);
+	urb->transfer_flags &= ~URB_NO_DMA_MAP;
 }
 
 /**
@@ -1336,7 +1343,8 @@ int usb_buffer_map_sg (struct usb_device *dev, unsigned pipe,
 	if (!dev
 			|| usb_pipecontrol (pipe)
 			|| !(bus = dev->bus)
-			|| !(controller = bus->controller))
+			|| !(controller = bus->controller)
+			|| !controller->dma_mask)
 		return -1;
 
 	// FIXME generic api broken like pci, can't report errors
@@ -1362,7 +1370,8 @@ void usb_buffer_dmasync_sg (struct usb_device *dev, unsigned pipe,
 
 	if (!dev
 			|| !(bus = dev->bus)
-			|| !(controller = bus->controller))
+			|| !(controller = bus->controller)
+			|| !controller->dma_mask)
 		return;
 
 	dma_sync_sg (controller, sg, n_hw_ents,
@@ -1386,7 +1395,8 @@ void usb_buffer_unmap_sg (struct usb_device *dev, unsigned pipe,
 
 	if (!dev
 			|| !(bus = dev->bus)
-			|| !(controller = bus->controller))
+			|| !(controller = bus->controller)
+			|| !controller->dma_mask)
 		return;
 
 	dma_unmap_sg (controller, sg, n_hw_ents,

drivers/usb/host/ehci.h

@@ -426,16 +426,6 @@ static inline int hcd_register_root (struct usb_hcd *hcd)
 
 #else	/* LINUX_VERSION_CODE */
 
-// hcd_to_bus() eventually moves to hcd.h on 2.5 too
-static inline struct usb_bus *hcd_to_bus (struct usb_hcd *hcd)
-	{ return &hcd->self; }
-// ... as does hcd_register_root()
-static inline int hcd_register_root (struct usb_hcd *hcd)
-{
-	return usb_register_root_hub (
-		hcd_to_bus (hcd)->root_hub, &hcd->pdev->dev);
-}
-
 #define SUBMIT_URB(urb,mem_flags) usb_submit_urb(urb,mem_flags)
 
 #ifndef DEBUG

drivers/usb/host/hc_simple.c

@@ -219,7 +219,7 @@ static int hci_unlink_urb (struct urb * urb)
 	if (!list_empty (&urb->urb_list) && urb->status == -EINPROGRESS) {
 		/* URB active? */
 
-		if (urb->transfer_flags & (URB_ASYNC_UNLINK | URB_TIMEOUT_KILLED)) {
+		if (urb->transfer_flags & URB_ASYNC_UNLINK) {
 			/* asynchronous with callback */
 			/* relink the urb to the del list */
 			list_move (&urb->urb_list, &hci->del_list);
@@ -388,7 +388,6 @@ static void qu_urb_timeout (unsigned long lurb)
 	struct urb *urb = (struct urb *) lurb;
 
 	DBGFUNC ("enter qu_urb_timeout\n");
-	urb->transfer_flags |= URB_TIMEOUT_KILLED;
 	hci_unlink_urb (urb);
 }
 #endif

drivers/usb/host/uhci-hcd.c

@@ -1747,7 +1747,6 @@ static void stall_callback(unsigned long ptr)
 
 		tmp = tmp->next;
 
-		u->transfer_flags |= URB_TIMEOUT_KILLED;
 		uhci_urb_dequeue(hcd, u);
 	}
 

include/linux/usb.h

@@ -554,7 +554,6 @@ extern int usb_disabled(void);
 #define URB_NO_FSBR		0x0020	/* UHCI-specific */
 #define URB_ZERO_PACKET		0x0040	/* Finish bulk OUTs with short packet */
 #define URB_NO_INTERRUPT	0x0080	/* HINT: no non-error interrupt needed */
-#define URB_TIMEOUT_KILLED	0x1000	/* only set by HCD! */
 
 struct usb_iso_packet_descriptor {
 	unsigned int offset;