Commit the first of half of changes that allow busdma to transparently

honor the alignment and boundary constraints in the dma tag when loading
buffers.  Previously, these constraints were only honored when allocating
memory via bus_dmamem_alloc().  Now, bus_dmamap_load() will automatically
use bounce buffers when needed.

Also add a set of sysctls to monitor the global busdma stats.  These are:

hw.busdma.free_bpages
hw.busdma.reserved_bpages
hw.busdma.active_bpages
hw.busdma.total_bpages
hw.busdma.total_bounced
hw.busdma.total_deferred

1 files changed, 47 insertions, 11 deletions

diff --git a/sys/i386/i386/busdma_machdep.c b/sys/i386/i386/busdma_machdep.c
index 54c60e5..455f956 100644
--- a/sys/i386/i386/busdma_machdep.c
+++ b/sys/i386/i386/busdma_machdep.c
@@ -38,6 +38,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/mutex.h>
 #include <sys/mbuf.h>
 #include <sys/uio.h>
+#include <sys/sysctl.h>
 
 #include <vm/vm.h>
 #include <vm/vm_page.h>
@@ -84,8 +85,24 @@ static int free_bpages;
 static int reserved_bpages;
 static int active_bpages;
 static int total_bpages;
+static int total_bounced;
+static int total_deferred;
 static bus_addr_t bounce_lowaddr = BUS_SPACE_MAXADDR;
 
+SYSCTL_NODE(_hw, OID_AUTO, busdma, CTLFLAG_RD, 0, "Busdma parameters");
+SYSCTL_INT(_hw_busdma, OID_AUTO, free_bpages, CTLFLAG_RD, &free_bpages, 0,
+	   "Free bounce pages");
+SYSCTL_INT(_hw_busdma, OID_AUTO, reserved_bpages, CTLFLAG_RD, &reserved_bpages,
+	   0, "Reserved bounce pages");
+SYSCTL_INT(_hw_busdma, OID_AUTO, active_bpages, CTLFLAG_RD, &active_bpages, 0,
+	   "Active bounce pages");
+SYSCTL_INT(_hw_busdma, OID_AUTO, total_bpages, CTLFLAG_RD, &total_bpages, 0,
+	   "Total bounce pages");
+SYSCTL_INT(_hw_busdma, OID_AUTO, total_bounced, CTLFLAG_RD, &total_bounced, 0,
+	   "Total bounce requests");
+SYSCTL_INT(_hw_busdma, OID_AUTO, total_deferred, CTLFLAG_RD, &total_deferred, 0,
+	   "Total bounce requests that were deferred");
+
 struct bus_dmamap {
 	struct bp_list	       bpages;
 	int		       pagesneeded;
@@ -109,7 +126,8 @@ static int reserve_bounce_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
 static bus_addr_t add_bounce_page(bus_dma_tag_t dmat, bus_dmamap_t map,
 				   vm_offset_t vaddr, bus_size_t size);
 static void free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage);
-static __inline int run_filter(bus_dma_tag_t dmat, bus_addr_t paddr);
+static __inline int run_filter(bus_dma_tag_t dmat, bus_addr_t paddr,
+			       bus_size_t len);
 
 /*
  * Return true if a match is made.
@@ -120,14 +138,18 @@ static __inline int run_filter(bus_dma_tag_t dmat, bus_addr_t paddr);
  * to check for a match, if there is no filter callback then assume a match.
  */
 static __inline int
-run_filter(bus_dma_tag_t dmat, bus_addr_t paddr)
+run_filter(bus_dma_tag_t dmat, bus_addr_t paddr, bus_size_t len)
 {
+	bus_size_t bndy;
 	int retval;
 
 	retval = 0;
+	bndy = dmat->boundary;
+
 	do {
-		if (paddr > dmat->lowaddr
-		 && paddr <= dmat->highaddr
+		if (((paddr > dmat->lowaddr && paddr <= dmat->highaddr)
+		 || ((paddr & (dmat->alignment - 1)) != 0)
+		 || ((paddr & bndy) != ((paddr + len) & bndy)))
 		 && (dmat->filter == NULL
 		  || (*dmat->filter)(dmat->filterarg, paddr) != 0))
 			retval = 1;
@@ -188,6 +210,10 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
 	bus_dma_tag_t newtag;
 	int error = 0;
 
+	/* Basic sanity checking */
+	if (boundary != 0 && boundary < maxsegsz)
+		maxsegsz = boundary;
+
 	/* Return a NULL tag on failure */
 	*dmat = NULL;
 
@@ -322,7 +348,13 @@ bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
 			return (ENOMEM);
 	}
 
-	if (dmat->lowaddr < ptoa((vm_paddr_t)Maxmem)) {
+	/*
+	 * Bouncing might be required if the driver asks for an active
+	 * exclusion region, a data alignment that is stricter than 1, and/or
+	 * an active address boundary.
+	 */
+	if (dmat->lowaddr < ptoa((vm_paddr_t)Maxmem)
+	 || dmat->alignment > 1 || dmat->boundary > 0) {
 		/* Must bounce */
 		int maxpages;
 
@@ -340,8 +372,7 @@ bus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
 		 */
 		maxpages = MIN(MAX_BPAGES, Maxmem - atop(dmat->lowaddr));
 		if ((dmat->flags & BUS_DMA_MIN_ALLOC_COMP) == 0
-		 || (dmat->map_count > 0
-		  && total_bpages < maxpages)) {
+		 || (dmat->map_count > 0 && total_bpages < maxpages)) {
 			int pages;
 
 			if (dmat->lowaddr > bounce_lowaddr) {
@@ -426,6 +457,7 @@ bus_dmamem_alloc(bus_dma_tag_t dmat, void** vaddr, int flags,
 		 * XXX Use Contigmalloc until it is merged into this facility
 		 *     and handles multi-seg allocations.  Nobody is doing
 		 *     multi-seg allocations yet though.
+		 * XXX Certain AGP hardware does.
 		 */
 		*vaddr = contigmalloc(dmat->maxsize, M_DEVBUF, mflags,
 		    0ul, dmat->lowaddr, dmat->alignment? dmat->alignment : 1ul,
@@ -492,8 +524,9 @@ _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
 	else
 		pmap = NULL;
 
-	if (dmat->lowaddr < ptoa((vm_paddr_t)Maxmem) &&
-	    map->pagesneeded == 0) {
+	if ((dmat->lowaddr < ptoa((vm_paddr_t)Maxmem)
+	 || dmat->boundary > 0 || dmat->alignment > 1)
+	 && map->pagesneeded == 0) {
 		vm_offset_t	vendaddr;
 
 		/*
@@ -505,7 +538,7 @@ _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
 
 		while (vaddr < vendaddr) {
 			paddr = pmap_kextract(vaddr);
-			if (run_filter(dmat, paddr) != 0) {
+			if (run_filter(dmat, paddr, 0) != 0) {
 				needbounce = 1;
 				map->pagesneeded++;
 			}
@@ -566,7 +599,7 @@ _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
 				sgsize = (baddr - curaddr);
 		}
 
-		if (map->pagesneeded != 0 && run_filter(dmat, curaddr))
+		if (map->pagesneeded != 0 && run_filter(dmat, curaddr, sgsize))
 			curaddr = add_bounce_page(dmat, map, vaddr, sgsize);
 
 		/*
@@ -763,6 +796,8 @@ _bus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
 		 * want to add support for invalidating
 		 * the caches on broken hardware
 		 */
+		total_bounced++;
+
 		if (op & BUS_DMASYNC_PREWRITE) {
 			while (bpage != NULL) {
 				bcopy((void *)bpage->datavaddr,
@@ -901,6 +936,7 @@ free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage)
 			STAILQ_INSERT_TAIL(&bounce_map_callbacklist,
 					   map, links);
 			busdma_swi_pending = 1;
+			total_deferred++;
 			swi_sched(vm_ih, 0);
 		}
 	}