usb gadget stack: remove usb_ep_*_buffer(), part 2

This patch removes controller driver infrastructure which supported
the now-removed usb_ep_{alloc,free}_buffer() calls.

As can be seen, many of the implementations of this were broken to
various degrees.  Many didn't properly return dma-coherent mappings;
those which did so were necessarily ugly because of bogosity in the
underlying dma_free_coherent() calls ... which on many platforms
can't be called from the same contexts (notably in_irq) from which
their dma_alloc_coherent() sibling can be called.

The main potential downside of removing this is that gadget drivers
wouldn't have specific knowledge that the controller drivers have:
endpoints that aren't dma-capable don't need any dma mappings at all.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/at91_udc.c

@@ -601,25 +601,6 @@ static void at91_ep_free_request(struct usb_ep *_ep, struct usb_request *_req)
 	kfree(req);
 }
 
-static void *at91_ep_alloc_buffer(
-	struct usb_ep *_ep,
-	unsigned bytes,
-	dma_addr_t *dma,
-	gfp_t gfp_flags)
-{
-	*dma = ~0;
-	return kmalloc(bytes, gfp_flags);
-}
-
-static void at91_ep_free_buffer(
-	struct usb_ep *ep,
-	void *buf,
-	dma_addr_t dma,
-	unsigned bytes)
-{
-	kfree(buf);
-}
-
 static int at91_ep_queue(struct usb_ep *_ep,
 			struct usb_request *_req, gfp_t gfp_flags)
 {
@@ -788,8 +769,6 @@ static const struct usb_ep_ops at91_ep_ops = {
 	.disable	= at91_ep_disable,
 	.alloc_request	= at91_ep_alloc_request,
 	.free_request	= at91_ep_free_request,
-	.alloc_buffer	= at91_ep_alloc_buffer,
-	.free_buffer	= at91_ep_free_buffer,
 	.queue		= at91_ep_queue,
 	.dequeue	= at91_ep_dequeue,
 	.set_halt	= at91_ep_set_halt,

drivers/usb/gadget/dummy_hcd.c

@@ -497,38 +497,6 @@ dummy_free_request (struct usb_ep *_ep, struct usb_request *_req)
 	kfree (req);
 }
 
-static void *
-dummy_alloc_buffer (
-	struct usb_ep *_ep,
-	unsigned bytes,
-	dma_addr_t *dma,
-	gfp_t mem_flags
-) {
-	char			*retval;
-	struct dummy_ep		*ep;
-	struct dummy		*dum;
-
-	ep = usb_ep_to_dummy_ep (_ep);
-	dum = ep_to_dummy (ep);
-
-	if (!dum->driver)
-		return NULL;
-	retval = kmalloc (bytes, mem_flags);
-	*dma = (dma_addr_t) retval;
-	return retval;
-}
-
-static void
-dummy_free_buffer (
-	struct usb_ep *_ep,
-	void *buf,
-	dma_addr_t dma,
-	unsigned bytes
-) {
-	if (bytes)
-		kfree (buf);
-}
-
 static void
 fifo_complete (struct usb_ep *ep, struct usb_request *req)
 {
@@ -659,10 +627,6 @@ static const struct usb_ep_ops dummy_ep_ops = {
 	.alloc_request	= dummy_alloc_request,
 	.free_request	= dummy_free_request,
 
-	.alloc_buffer	= dummy_alloc_buffer,
-	.free_buffer	= dummy_free_buffer,
-	/* map, unmap, ... eventually hook the "generic" dma calls */
-
 	.queue		= dummy_queue,
 	.dequeue	= dummy_dequeue,
 

drivers/usb/gadget/fsl_usb2_udc.c

@@ -601,39 +601,6 @@ static void fsl_free_request(struct usb_ep *_ep, struct usb_request *_req)
 		kfree(req);
 }
 
-/*------------------------------------------------------------------
- * Allocate an I/O buffer
-*---------------------------------------------------------------------*/
-static void *fsl_alloc_buffer(struct usb_ep *_ep, unsigned bytes,
-		dma_addr_t *dma, gfp_t gfp_flags)
-{
-	struct fsl_ep *ep;
-
-	if (!_ep)
-		return NULL;
-
-	ep = container_of(_ep, struct fsl_ep, ep);
-
-	return dma_alloc_coherent(ep->udc->gadget.dev.parent,
-			bytes, dma, gfp_flags);
-}
-
-/*------------------------------------------------------------------
- * frees an i/o buffer
-*---------------------------------------------------------------------*/
-static void fsl_free_buffer(struct usb_ep *_ep, void *buf,
-		dma_addr_t dma, unsigned bytes)
-{
-	struct fsl_ep *ep;
-
-	if (!_ep)
-		return;
-
-	ep = container_of(_ep, struct fsl_ep, ep);
-
-	dma_free_coherent(ep->udc->gadget.dev.parent, bytes, buf, dma);
-}
-
 /*-------------------------------------------------------------------------*/
 static int fsl_queue_td(struct fsl_ep *ep, struct fsl_req *req)
 {
@@ -1047,9 +1014,6 @@ static struct usb_ep_ops fsl_ep_ops = {
 	.alloc_request = fsl_alloc_request,
 	.free_request = fsl_free_request,
 
-	.alloc_buffer = fsl_alloc_buffer,
-	.free_buffer = fsl_free_buffer,
-
 	.queue = fsl_ep_queue,
 	.dequeue = fsl_ep_dequeue,
 

drivers/usb/gadget/goku_udc.c

@@ -296,51 +296,6 @@ goku_free_request(struct usb_ep *_ep, struct usb_request *_req)
 
 /*-------------------------------------------------------------------------*/
 
-/* allocating buffers this way eliminates dma mapping overhead, which
- * on some platforms will mean eliminating a per-io buffer copy.  with
- * some kinds of system caches, further tweaks may still be needed.
- */
-static void *
-goku_alloc_buffer(struct usb_ep *_ep, unsigned bytes,
-			dma_addr_t *dma, gfp_t gfp_flags)
-{
-	void		*retval;
-	struct goku_ep	*ep;
-
-	ep = container_of(_ep, struct goku_ep, ep);
-	if (!_ep)
-		return NULL;
-	*dma = DMA_ADDR_INVALID;
-
-	if (ep->dma) {
-		/* the main problem with this call is that it wastes memory
-		 * on typical 1/N page allocations: it allocates 1-N pages.
-		 */
-#warning Using dma_alloc_coherent even with buffers smaller than a page.
-		retval = dma_alloc_coherent(&ep->dev->pdev->dev,
-				bytes, dma, gfp_flags);
-	} else
-		retval = kmalloc(bytes, gfp_flags);
-	return retval;
-}
-
-static void
-goku_free_buffer(struct usb_ep *_ep, void *buf, dma_addr_t dma, unsigned bytes)
-{
-	/* free memory into the right allocator */
-	if (dma != DMA_ADDR_INVALID) {
-		struct goku_ep	*ep;
-
-		ep = container_of(_ep, struct goku_ep, ep);
-		if (!_ep)
-			return;
-		dma_free_coherent(&ep->dev->pdev->dev, bytes, buf, dma);
-	} else
-		kfree (buf);
-}
-
-/*-------------------------------------------------------------------------*/
-
 static void
 done(struct goku_ep *ep, struct goku_request *req, int status)
 {
@@ -1026,9 +981,6 @@ static struct usb_ep_ops goku_ep_ops = {
 	.alloc_request	= goku_alloc_request,
 	.free_request	= goku_free_request,
 
-	.alloc_buffer	= goku_alloc_buffer,
-	.free_buffer	= goku_free_buffer,
-
 	.queue		= goku_queue,
 	.dequeue	= goku_dequeue,
 

drivers/usb/gadget/lh7a40x_udc.c

@@ -75,10 +75,6 @@ static int lh7a40x_ep_enable(struct usb_ep *ep,
 static int lh7a40x_ep_disable(struct usb_ep *ep);
 static struct usb_request *lh7a40x_alloc_request(struct usb_ep *ep, gfp_t);
 static void lh7a40x_free_request(struct usb_ep *ep, struct usb_request *);
-static void *lh7a40x_alloc_buffer(struct usb_ep *ep, unsigned, dma_addr_t *,
-				  gfp_t);
-static void lh7a40x_free_buffer(struct usb_ep *ep, void *, dma_addr_t,
-				unsigned);
 static int lh7a40x_queue(struct usb_ep *ep, struct usb_request *, gfp_t);
 static int lh7a40x_dequeue(struct usb_ep *ep, struct usb_request *);
 static int lh7a40x_set_halt(struct usb_ep *ep, int);
@@ -104,9 +100,6 @@ static struct usb_ep_ops lh7a40x_ep_ops = {
 	.alloc_request = lh7a40x_alloc_request,
 	.free_request = lh7a40x_free_request,
 
-	.alloc_buffer = lh7a40x_alloc_buffer,
-	.free_buffer = lh7a40x_free_buffer,
-
 	.queue = lh7a40x_queue,
 	.dequeue = lh7a40x_dequeue,
 
@@ -1134,26 +1127,6 @@ static void lh7a40x_free_request(struct usb_ep *ep, struct usb_request *_req)
 	kfree(req);
 }
 
-static void *lh7a40x_alloc_buffer(struct usb_ep *ep, unsigned bytes,
-				  dma_addr_t * dma, gfp_t gfp_flags)
-{
-	char *retval;
-
-	DEBUG("%s (%p, %d, %d)\n", __FUNCTION__, ep, bytes, gfp_flags);
-
-	retval = kmalloc(bytes, gfp_flags & ~(__GFP_DMA | __GFP_HIGHMEM));
-	if (retval)
-		*dma = virt_to_bus(retval);
-	return retval;
-}
-
-static void lh7a40x_free_buffer(struct usb_ep *ep, void *buf, dma_addr_t dma,
-				unsigned bytes)
-{
-	DEBUG("%s, %p\n", __FUNCTION__, ep);
-	kfree(buf);
-}
-
 /** Queue one request
  *  Kickstart transfer if needed
  *  NOTE: Sets INDEX register

drivers/usb/gadget/net2280.c

@@ -450,100 +450,6 @@ net2280_free_request (struct usb_ep *_ep, struct usb_request *_req)
 
 /*-------------------------------------------------------------------------*/
 
-/*
- * dma-coherent memory allocation (for dma-capable endpoints)
- *
- * NOTE: the dma_*_coherent() API calls suck.  Most implementations are
- * (a) page-oriented, so small buffers lose big; and (b) asymmetric with
- * respect to calls with irqs disabled:  alloc is safe, free is not.
- * We currently work around (b), but not (a).
- */
-
-static void *
-net2280_alloc_buffer (
-	struct usb_ep		*_ep,
-	unsigned		bytes,
-	dma_addr_t		*dma,
-	gfp_t			gfp_flags
-)
-{
-	void			*retval;
-	struct net2280_ep	*ep;
-
-	ep = container_of (_ep, struct net2280_ep, ep);
-	if (!_ep)
-		return NULL;
-	*dma = DMA_ADDR_INVALID;
-
-	if (ep->dma)
-		retval = dma_alloc_coherent(&ep->dev->pdev->dev,
-				bytes, dma, gfp_flags);
-	else
-		retval = kmalloc(bytes, gfp_flags);
-	return retval;
-}
-
-static DEFINE_SPINLOCK(buflock);
-static LIST_HEAD(buffers);
-
-struct free_record {
-	struct list_head	list;
-	struct device		*dev;
-	unsigned		bytes;
-	dma_addr_t		dma;
-};
-
-static void do_free(unsigned long ignored)
-{
-	spin_lock_irq(&buflock);
-	while (!list_empty(&buffers)) {
-		struct free_record	*buf;
-
-		buf = list_entry(buffers.next, struct free_record, list);
-		list_del(&buf->list);
-		spin_unlock_irq(&buflock);
-
-		dma_free_coherent(buf->dev, buf->bytes, buf, buf->dma);
-
-		spin_lock_irq(&buflock);
-	}
-	spin_unlock_irq(&buflock);
-}
-
-static DECLARE_TASKLET(deferred_free, do_free, 0);
-
-static void
-net2280_free_buffer (
-	struct usb_ep *_ep,
-	void *address,
-	dma_addr_t dma,
-	unsigned bytes
-) {
-	/* free memory into the right allocator */
-	if (dma != DMA_ADDR_INVALID) {
-		struct net2280_ep	*ep;
-		struct free_record	*buf = address;
-		unsigned long		flags;
-
-		ep = container_of(_ep, struct net2280_ep, ep);
-		if (!_ep)
-			return;
-
-		ep = container_of (_ep, struct net2280_ep, ep);
-		buf->dev = &ep->dev->pdev->dev;
-		buf->bytes = bytes;
-		buf->dma = dma;
-
-		spin_lock_irqsave(&buflock, flags);
-		list_add_tail(&buf->list, &buffers);
-		tasklet_schedule(&deferred_free);
-		spin_unlock_irqrestore(&buflock, flags);
-	} else
-		kfree (address);
-}
-
-/*-------------------------------------------------------------------------*/
-
 /* load a packet into the fifo we use for usb IN transfers.
  * works for all endpoints.
  *
@@ -1392,9 +1298,6 @@ static const struct usb_ep_ops net2280_ep_ops = {
 	.alloc_request	= net2280_alloc_request,
 	.free_request	= net2280_free_request,
 
-	.alloc_buffer	= net2280_alloc_buffer,
-	.free_buffer	= net2280_free_buffer,
-
 	.queue		= net2280_queue,
 	.dequeue	= net2280_dequeue,
 

drivers/usb/gadget/omap_udc.c

@@ -296,111 +296,6 @@ omap_free_request(struct usb_ep *ep, struct usb_request *_req)
 
 /*-------------------------------------------------------------------------*/
 
-/*
- * dma-coherent memory allocation (for dma-capable endpoints)
- *
- * NOTE: the dma_*_coherent() API calls suck.  Most implementations are
- * (a) page-oriented, so small buffers lose big; and (b) asymmetric with
- * respect to calls with irqs disabled:  alloc is safe, free is not.
- * We currently work around (b), but not (a).
- */
-
-static void *
-omap_alloc_buffer(
-	struct usb_ep	*_ep,
-	unsigned	bytes,
-	dma_addr_t	*dma,
-	gfp_t		gfp_flags
-)
-{
-	void		*retval;
-	struct omap_ep	*ep;
-
-	if (!_ep)
-		return NULL;
-
-	ep = container_of(_ep, struct omap_ep, ep);
-	if (use_dma && ep->has_dma) {
-		static int	warned;
-		if (!warned && bytes < PAGE_SIZE) {
-			dev_warn(ep->udc->gadget.dev.parent,
-				"using dma_alloc_coherent for "
-				"small allocations wastes memory\n");
-			warned++;
-		}
-		return dma_alloc_coherent(ep->udc->gadget.dev.parent,
-				bytes, dma, gfp_flags);
-	}
-
-	retval = kmalloc(bytes, gfp_flags);
-	if (retval)
-		*dma = virt_to_phys(retval);
-	return retval;
-}
-
-static DEFINE_SPINLOCK(buflock);
-static LIST_HEAD(buffers);
-
-struct free_record {
-	struct list_head	list;
-	struct device		*dev;
-	unsigned		bytes;
-	dma_addr_t		dma;
-};
-
-static void do_free(unsigned long ignored)
-{
-	spin_lock_irq(&buflock);
-	while (!list_empty(&buffers)) {
-		struct free_record	*buf;
-
-		buf = list_entry(buffers.next, struct free_record, list);
-		list_del(&buf->list);
-		spin_unlock_irq(&buflock);
-
-		dma_free_coherent(buf->dev, buf->bytes, buf, buf->dma);
-
-		spin_lock_irq(&buflock);
-	}
-	spin_unlock_irq(&buflock);
-}
-
-static DECLARE_TASKLET(deferred_free, do_free, 0);
-
-static void omap_free_buffer(
-	struct usb_ep	*_ep,
-	void		*buf,
-	dma_addr_t	dma,
-	unsigned	bytes
-)
-{
-	if (!_ep) {
-		WARN_ON(1);
-		return;
-	}
-
-	/* free memory into the right allocator */
-	if (dma != DMA_ADDR_INVALID) {
-		struct omap_ep		*ep;
-		struct free_record	*rec = buf;
-		unsigned long		flags;
-
-		ep = container_of(_ep, struct omap_ep, ep);
-
-		rec->dev = ep->udc->gadget.dev.parent;
-		rec->bytes = bytes;
-		rec->dma = dma;
-
-		spin_lock_irqsave(&buflock, flags);
-		list_add_tail(&rec->list, &buffers);
-		tasklet_schedule(&deferred_free);
-		spin_unlock_irqrestore(&buflock, flags);
-	} else
-		kfree(buf);
-}
-
-/*-------------------------------------------------------------------------*/
-
 static void
 done(struct omap_ep *ep, struct omap_req *req, int status)
 {
@@ -1271,9 +1166,6 @@ static struct usb_ep_ops omap_ep_ops = {
 	.alloc_request	= omap_alloc_request,
 	.free_request	= omap_free_request,
 
-	.alloc_buffer	= omap_alloc_buffer,
-	.free_buffer	= omap_free_buffer,
-
 	.queue		= omap_ep_queue,
 	.dequeue	= omap_ep_dequeue,
 

drivers/usb/gadget/pxa2xx_udc.c

@@ -341,26 +341,6 @@ pxa2xx_ep_free_request (struct usb_ep *_ep, struct usb_request *_req)
 	kfree(req);
 }
 
-
-static void *
-pxa2xx_ep_alloc_buffer(struct usb_ep *_ep, unsigned bytes,
-	dma_addr_t *dma, gfp_t gfp_flags)
-{
-	char			*retval;
-
-	retval = kmalloc (bytes, gfp_flags & ~(__GFP_DMA|__GFP_HIGHMEM));
-	if (retval)
-		*dma = (dma_addr_t)~0;
-	return retval;
-}
-
-static void
-pxa2xx_ep_free_buffer(struct usb_ep *_ep, void *buf, dma_addr_t dma,
-		unsigned bytes)
-{
-	kfree (buf);
-}
-
 /*-------------------------------------------------------------------------*/
 
 /*
@@ -927,9 +907,6 @@ static struct usb_ep_ops pxa2xx_ep_ops = {
 	.alloc_request	= pxa2xx_ep_alloc_request,
 	.free_request	= pxa2xx_ep_free_request,
 
-	.alloc_buffer	= pxa2xx_ep_alloc_buffer,
-	.free_buffer	= pxa2xx_ep_free_buffer,
-
 	.queue		= pxa2xx_ep_queue,
 	.dequeue	= pxa2xx_ep_dequeue,
 

drivers/usb/gadget/s3c2410_udc.c

@@ -1196,36 +1196,6 @@ s3c2410_udc_free_request(struct usb_ep *_ep, struct usb_request *_req)
 	kfree(req);
 }
 
-/*
- *	s3c2410_udc_alloc_buffer
- */
-static void *s3c2410_udc_alloc_buffer(struct usb_ep *_ep,
-		unsigned bytes, dma_addr_t *dma, gfp_t mem_flags)
-{
-	char *retval;
-
-	dprintk(DEBUG_VERBOSE, "%s()\n", __func__);
-
-	if (!the_controller->driver)
-		return NULL;
-
-	retval = kmalloc (bytes, mem_flags);
-	*dma = (dma_addr_t) retval;
-	return retval;
-}
-
-/*
- * s3c2410_udc_free_buffer
- */
-static void s3c2410_udc_free_buffer (struct usb_ep *_ep, void *buf,
-		dma_addr_t dma, unsigned bytes)
-{
-	dprintk(DEBUG_VERBOSE, "%s()\n", __func__);
-
-	if (bytes)
-		kfree (buf);
-}
-
 /*
  *	s3c2410_udc_queue
  */
@@ -1441,9 +1411,6 @@ static const struct usb_ep_ops s3c2410_ep_ops = {
 	.alloc_request	= s3c2410_udc_alloc_request,
 	.free_request	= s3c2410_udc_free_request,
 
-	.alloc_buffer	= s3c2410_udc_alloc_buffer,
-	.free_buffer	= s3c2410_udc_free_buffer,
-
 	.queue		= s3c2410_udc_queue,
 	.dequeue	= s3c2410_udc_dequeue,
 

include/linux/usb_gadget.h

@@ -110,13 +110,6 @@ struct usb_ep_ops {
 		gfp_t gfp_flags);
 	void (*free_request) (struct usb_ep *ep, struct usb_request *req);
 
-	void *(*alloc_buffer) (struct usb_ep *ep, unsigned bytes,
-		dma_addr_t *dma, gfp_t gfp_flags);
-	void (*free_buffer) (struct usb_ep *ep, void *buf, dma_addr_t dma,
-		unsigned bytes);
-	// NOTE:  on 2.6, drivers may also use dma_map() and
-	// dma_sync_single_*() to directly manage dma overhead. 
-
 	int (*queue) (struct usb_ep *ep, struct usb_request *req,
 		gfp_t gfp_flags);
 	int (*dequeue) (struct usb_ep *ep, struct usb_request *req);