Add helper function to check if a USB page cache buffer is properly

aligned to reduce the use of bounce buffers in PIO mode.

MFC after:	1 week

diff --git a/sys/dev/usb/usb_busdma.c b/sys/dev/usb/usb_busdma.c
index d9c198774f7adf9ed761f00782a42deff6cdfa68..821e0fb816ebafdfa67c6d11cf9f8a3d433600ed 100644 (file)
--- a/sys/dev/usb/usb_busdma.c
+++ b/sys/dev/usb/usb_busdma.c
@@ -133,6 +133,35 @@ usbd_get_page(struct usb_page_cache *pc, usb_frlength_t offset,
 #endif
 }
 
+/*------------------------------------------------------------------------*
+ *  usb_pc_buffer_is_aligned - verify alignment
+ * 
+ * This function is used to check if a page cache buffer is properly
+ * aligned to reduce the use of bounce buffers in PIO mode.
+ *------------------------------------------------------------------------*/
+uint8_t
+usb_pc_buffer_is_aligned(struct usb_page_cache *pc, usb_frlength_t offset,
+    usb_frlength_t len, usb_frlength_t mask)
+{
+       struct usb_page_search buf_res;
+
+       while (len != 0) {
+
+               usbd_get_page(pc, offset, &buf_res);
+
+               if (buf_res.length > len)
+                       buf_res.length = len;
+               if (USB_P2U(buf_res.buffer) & mask)
+                       return (0);
+               if (buf_res.length & mask)
+                       return (0);
+
+               offset += buf_res.length;
+               len -= buf_res.length;
+       }
+       return (1);
+}
+
 /*------------------------------------------------------------------------*
  *  usbd_copy_in - copy directly to DMA-able memory
  *------------------------------------------------------------------------*/

diff --git a/sys/dev/usb/usb_busdma.h b/sys/dev/usb/usb_busdma.h
index eee91f36893f1df15ad77770a3383770d196b37c..077bf8b86417af27b34b33ed1371b8b8a10152c6 100644 (file)
--- a/sys/dev/usb/usb_busdma.h
+++ b/sys/dev/usb/usb_busdma.h
@@ -159,5 +159,8 @@ void        usb_pc_cpu_flush(struct usb_page_cache *pc);
 void   usb_pc_cpu_invalidate(struct usb_page_cache *pc);
 void   usb_pc_dmamap_destroy(struct usb_page_cache *pc);
 void   usb_pc_free_mem(struct usb_page_cache *pc);
+uint8_t        usb_pc_buffer_is_aligned(struct usb_page_cache *pc,
+           usb_frlength_t offset, usb_frlength_t len,
+           usb_frlength_t mask);
 
 #endif                                 /* _USB_BUSDMA_H_ */