busdma: Option to round to cache lines on sync

Some targets support only flushing or invalidating complete cache lines.
In this cases misaligned buffers might lead to unexpected results. This
patch adds a flag that allows drivers to signal to the bus dma driver
that it is OK to round a buffer to the next full cache line. That's for
example necessary if a driver wants to send out 14 byte via a USB DMA.
Only the driver knows whether these 14 bytes are located in an otherwise
unused cache line aligned buffer.

5 files changed, 66 insertions, 0 deletions

diff --git a/freebsd/sys/dev/usb/usb_busdma.c b/freebsd/sys/dev/usb/usb_busdma.c
index dc52fe15..b74f0823 100644
--- a/freebsd/sys/dev/usb/usb_busdma.c
+++ b/freebsd/sys/dev/usb/usb_busdma.c
@@ -67,6 +67,9 @@
 #include <dev/usb/usb_controller.h>
 #include <dev/usb/usb_bus.h>
 #endif			/* USB_GLOBAL_INCLUDE_FILE */
+#ifdef __rtems__
+#include <machine/rtems-bsd-cache.h>
+#endif /* __rtems__ */
 
 #if USB_HAVE_BUSDMA
 static void	usb_dma_tag_create(struct usb_dma_tag *, usb_size_t, usb_size_t);
@@ -543,6 +546,15 @@ usb_pc_alloc_mem(struct usb_page_cache *pc, struct usb_page *pg,
 
 	uptag = pc->tag_parent;
 
+#if defined(__rtems__) && defined(CPU_DATA_CACHE_ALIGNMENT)
+	while (align % CPU_DATA_CACHE_ALIGNMENT != 0) {
+		align *= 2;
+	}
+	if (size % CPU_DATA_CACHE_ALIGNMENT != 0) {
+		size = (size + (CPU_DATA_CACHE_ALIGNMENT - 1)) &
+		    ~(CPU_DATA_CACHE_ALIGNMENT - 1);
+	}
+#endif /* __rtems__ */
 	if (align != 1) {
 		/*
 	         * The alignment must be greater or equal to the
@@ -605,7 +617,12 @@ usb_pc_alloc_mem(struct usb_page_cache *pc, struct usb_page *pg,
 	/* load memory into DMA */
 	err = bus_dmamap_load(
 	    utag->tag, map, ptr, size, &usb_pc_alloc_mem_cb,
+#if defined(__rtems__) && CPU_DATA_CACHE_ALIGNMENT
+	    pc, (BUS_DMA_WAITOK | BUS_DMA_COHERENT |
+	    BUS_DMA_DO_CACHE_LINE_BLOW_UP));
+#else /* __rtems__ */
 	    pc, (BUS_DMA_WAITOK | BUS_DMA_COHERENT));
+#endif /* __rtems__ */
 
 	if (err == EINPROGRESS) {
 		cv_wait(uptag->cv, uptag->mtx);
@@ -662,6 +679,12 @@ usb_pc_free_mem(struct usb_page_cache *pc)
 uint8_t
 usb_pc_load_mem(struct usb_page_cache *pc, usb_size_t size, uint8_t sync)
 {
+#ifdef __rtems__
+	int flags;
+
+	flags = pc->dma_do_cache_line_blow_up ?
+	    BUS_DMA_DO_CACHE_LINE_BLOW_UP : 0;
+#endif /* __rtems__ */
 	/* setup page cache */
 	pc->page_offset_buf = 0;
 	pc->page_offset_end = size;
@@ -687,7 +710,11 @@ usb_pc_load_mem(struct usb_page_cache *pc, usb_size_t size, uint8_t sync)
 			 */
 			err = bus_dmamap_load(
 			    pc->tag, pc->map, pc->buffer, size,
+#ifndef __rtems__
 			    &usb_pc_alloc_mem_cb, pc, BUS_DMA_WAITOK);
+#else /* __rtems__ */
+			    &usb_pc_alloc_mem_cb, pc, BUS_DMA_WAITOK | flags);
+#endif /* __rtems__ */
 			if (err == EINPROGRESS) {
 				cv_wait(uptag->cv, uptag->mtx);
 				err = 0;
@@ -709,7 +736,11 @@ usb_pc_load_mem(struct usb_page_cache *pc, usb_size_t size, uint8_t sync)
 			 */
 			if (bus_dmamap_load(
 			    pc->tag, pc->map, pc->buffer, size,
+#ifndef __rtems__
 			    &usb_pc_load_mem_cb, pc, BUS_DMA_WAITOK)) {
+#else /* __rtems__ */
+			    &usb_pc_load_mem_cb, pc, BUS_DMA_WAITOK | flags)) {
+#endif /* __rtems__ */
 			}
 		}
 	} else {
diff --git a/freebsd/sys/dev/usb/usb_busdma.h b/freebsd/sys/dev/usb/usb_busdma.h
index d75e67ee..03eca30d 100644
--- a/freebsd/sys/dev/usb/usb_busdma.h
+++ b/freebsd/sys/dev/usb/usb_busdma.h
@@ -102,6 +102,11 @@ struct usb_page_cache {
 					 * from the memory. Else write. */
 	uint8_t	ismultiseg:1;		/* set if we can have multiple
 					 * segments */
+#ifdef __rtems__
+	uint8_t dma_do_cache_line_blow_up:1;
+					/* set if it is OK to align the buffer
+					 * start and end to next cache line */
+#endif /* __rtems__ */
 #endif
 };
 
diff --git a/freebsd/sys/dev/usb/usb_transfer.c b/freebsd/sys/dev/usb/usb_transfer.c
index 3b67c20c..ee1e4c28 100644
--- a/freebsd/sys/dev/usb/usb_transfer.c
+++ b/freebsd/sys/dev/usb/usb_transfer.c
@@ -2195,6 +2195,9 @@ usbd_xfer_set_frame_data(struct usb_xfer *xfer, usb_frcount_t frindex,
 	/* set virtual address to load and length */
 	xfer->frbuffers[frindex].buffer = ptr;
 	usbd_xfer_set_frame_len(xfer, frindex, len);
+#ifdef __rtems__
+	xfer->frbuffers[frindex].dma_do_cache_line_blow_up = 0;
+#endif /* __rtems__ */
 }
 
 void
@@ -2209,6 +2212,23 @@ usbd_xfer_frame_data(struct usb_xfer *xfer, usb_frcount_t frindex,
 		*len = xfer->frlengths[frindex];
 }
 
+#ifdef __rtems__
+/*------------------------------------------------------------------------*
+ *	usbd_xfer_frame_allow_cache_line_blow_up
+ *
+ * Set a flag that the buffer start and end belonging to this frame can be
+ * aligned to the next cache line on sync and flush.
+ *------------------------------------------------------------------------*/
+void
+usbd_xfer_frame_allow_cache_line_blow_up(struct usb_xfer *xfer,
+    usb_frcount_t frindex)
+{
+	KASSERT(frindex < xfer->max_frame_count, ("frame index overflow"));
+
+	xfer->frbuffers[frindex].dma_do_cache_line_blow_up = 1;
+}
+
+#endif /* __rtems__ */
 /*------------------------------------------------------------------------*
  *	usbd_xfer_old_frame_length
  *
diff --git a/freebsd/sys/dev/usb/usbdi.h b/freebsd/sys/dev/usb/usbdi.h
index 0a393844..834810a8 100644
--- a/freebsd/sys/dev/usb/usbdi.h
+++ b/freebsd/sys/dev/usb/usbdi.h
@@ -640,6 +640,10 @@ void	usbd_xfer_set_frame_data(struct usb_xfer *xfer, usb_frcount_t frindex,
 	    void *ptr, usb_frlength_t len);
 void	usbd_xfer_frame_data(struct usb_xfer *xfer, usb_frcount_t frindex,
 	    void **ptr, int *len);
+#ifdef __rtems__
+void	usbd_xfer_frame_allow_cache_line_blow_up(struct usb_xfer *xfer,
+	    usb_frcount_t frindex);
+#endif /* __rtems__ */
 void	usbd_xfer_set_frame_offset(struct usb_xfer *xfer, usb_frlength_t offset,
 	    usb_frcount_t frindex);
 usb_frlength_t usbd_xfer_max_len(struct usb_xfer *xfer);
diff --git a/freebsd/sys/sys/bus_dma.h b/freebsd/sys/sys/bus_dma.h
index e99d8ece..d5a08be0 100644
--- a/freebsd/sys/sys/bus_dma.h
+++ b/freebsd/sys/sys/bus_dma.h
@@ -107,6 +107,12 @@
 #define	BUS_DMA_KEEP_PG_OFFSET	0x400
 
 #define	BUS_DMA_LOAD_MBUF	0x800
+#ifdef __rtems__
+/*
+ * Hint that the start address and size can be aligned to the next cache line.
+ */
+#define BUS_DMA_DO_CACHE_LINE_BLOW_UP	0x80000000
+#endif /* __rtems__ */
 
 /* Forwards needed by prototypes below. */
 union ccb;