usb: add a hcd_uses_dma helper

The USB buffer allocation code is the only place in the usb core (and in
fact the whole kernel) that uses is_device_dma_capable, while the URB
mapping code uses the uses_dma flag in struct usb_bus.  Switch the buffer
allocation to use the uses_dma flag used by the rest of the USB code,
and create a helper in hcd.h that checks this flag as well as the
CONFIG_HAS_DMA to simplify the caller a bit.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20190811080520.21712-3-hch@lst.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/buffer.c

@@ -66,9 +66,7 @@ int hcd_buffer_create(struct usb_hcd *hcd)
 	char		name[16];
 	int		i, size;
 
-	if (hcd->localmem_pool ||
-	    !IS_ENABLED(CONFIG_HAS_DMA) ||
-	    !is_device_dma_capable(hcd->self.sysdev))
+	if (hcd->localmem_pool || !hcd_uses_dma(hcd))
 		return 0;
 
 	for (i = 0; i < HCD_BUFFER_POOLS; i++) {
@@ -129,8 +127,7 @@ void *hcd_buffer_alloc(
 		return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);
 
 	/* some USB hosts just use PIO */
-	if (!IS_ENABLED(CONFIG_HAS_DMA) ||
-	    !is_device_dma_capable(bus->sysdev)) {
+	if (!hcd_uses_dma(hcd)) {
 		*dma = ~(dma_addr_t) 0;
 		return kmalloc(size, mem_flags);
 	}
@@ -160,8 +157,7 @@ void hcd_buffer_free(
 		return;
 	}
 
-	if (!IS_ENABLED(CONFIG_HAS_DMA) ||
-	    !is_device_dma_capable(bus->sysdev)) {
+	if (!hcd_uses_dma(hcd)) {
 		kfree(addr);
 		return;
 	}

drivers/usb/core/hcd.c

@@ -1412,7 +1412,7 @@ int usb_hcd_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
 	if (usb_endpoint_xfer_control(&urb->ep->desc)) {
 		if (hcd->self.uses_pio_for_control)
 			return ret;
-		if (IS_ENABLED(CONFIG_HAS_DMA) && hcd->self.uses_dma) {
+		if (hcd_uses_dma(hcd)) {
 			if (is_vmalloc_addr(urb->setup_packet)) {
 				WARN_ONCE(1, "setup packet is not dma capable\n");
 				return -EAGAIN;
@@ -1446,7 +1446,7 @@ int usb_hcd_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
 	dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
 	if (urb->transfer_buffer_length != 0
 	    && !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) {
-		if (IS_ENABLED(CONFIG_HAS_DMA) && hcd->self.uses_dma) {
+		if (hcd_uses_dma(hcd)) {
 			if (urb->num_sgs) {
 				int n;
 

drivers/usb/dwc2/hcd.c

@@ -4608,7 +4608,7 @@ static int _dwc2_hcd_urb_enqueue(struct usb_hcd *hcd, struct urb *urb,
 
 	buf = urb->transfer_buffer;
 
-	if (hcd->self.uses_dma) {
+	if (hcd_uses_dma(hcd)) {
 		if (!buf && (urb->transfer_dma & 3)) {
 			dev_err(hsotg->dev,
 				"%s: unaligned transfer with no transfer_buffer",

include/linux/usb.h

@@ -1457,7 +1457,7 @@ typedef void (*usb_complete_t)(struct urb *);
  * field rather than determining a dma address themselves.
  *
  * Note that transfer_buffer must still be set if the controller
- * does not support DMA (as indicated by bus.uses_dma) and when talking
+ * does not support DMA (as indicated by hcd_uses_dma()) and when talking
  * to root hub. If you have to trasfer between highmem zone and the device
  * on such controller, create a bounce buffer or bail out with an error.
  * If transfer_buffer cannot be set (is in highmem) and the controller is DMA

include/linux/usb/hcd.h

@@ -422,6 +422,9 @@ static inline bool hcd_periodic_completion_in_progress(struct usb_hcd *hcd,
 	return hcd->high_prio_bh.completing_ep == ep;
 }
 
+#define hcd_uses_dma(hcd) \
+	(IS_ENABLED(CONFIG_HAS_DMA) && (hcd)->self.uses_dma)
+
 extern int usb_hcd_link_urb_to_ep(struct usb_hcd *hcd, struct urb *urb);
 extern int usb_hcd_check_unlink_urb(struct usb_hcd *hcd, struct urb *urb,
 		int status);