From: Markus Pfeiffer <markus.pfeiffer@morphism.de>
Date: Wed, 4 Jul 2012 13:31:38 +0000 (+0000)
Subject: kernel - Add BUS_DMA_KEEP_PG_OFFSET (i386)
X-Git-Tag: v3.2.0~692
X-Git-Url: http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/be46f3bf23325bf9536c44699d5423134d88c844

kernel - Add BUS_DMA_KEEP_PG_OFFSET (i386)

Add BUS_DMA_KEEP_PG_OFFSET from FreeBSD in preparation of import of
FreeBSD's USB stack
---

diff --git a/sys/platform/pc32/i386/busdma_machdep.c b/sys/platform/pc32/i386/busdma_machdep.c
index b6e7a8a..a8cff4e 100644
--- a/sys/platform/pc32/i386/busdma_machdep.c
+++ b/sys/platform/pc32/i386/busdma_machdep.c
@@ -1371,6 +1371,11 @@ add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map, vm_offset_t vaddr,
 
 	BZ_UNLOCK(bz);
 
+	if (dmat->flags & BUS_DMA_KEEP_PG_OFFSET) {
+		/* Page offset needs to be preserved. */
+		bpage->vaddr |= vaddr & PAGE_MASK;
+		bpage->busaddr |= vaddr & PAGE_MASK;
+	}
 	bpage->datavaddr = vaddr;
 	bpage->datacount = size;
 	STAILQ_INSERT_TAIL(&map->bpages, bpage, links);
@@ -1386,6 +1391,16 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
 	bpage->datavaddr = 0;
 	bpage->datacount = 0;
 
+	if (dmat->flags & BUS_DMA_KEEP_PG_OFFSET) {
+		/*
+		 * Reset the bounce page to start at offset 0.  Other uses
+		 * of this bounce page may need to store a full page of
+		 * data and/or assume it starts on a page boundary.
+		 */
+		bpage->vaddr &= ~PAGE_MASK;
+		bpage->busaddr &= ~PAGE_MASK;
+	}
+
 	BZ_LOCK(bz);
 
 	STAILQ_INSERT_HEAD(&bz->bounce_page_list, bpage, links);