add MD PMAP_NOCACHE flag to i386 and use it to implement the

BUS_DMA_NOCACHE flag with guarantees that the dma memory will be mapped
uncached. Some broken/odd hardware needs this.

discussion with miod, toby, art and kettenis. ok miod.

4 files changed, 17 insertions, 6 deletions

diff --git a/sys/arch/i386/i386/bus_dma.c b/sys/arch/i386/i386/bus_dma.c
index ab75b0d9bbe..f2fbc9ff40c 100644
--- a/sys/arch/i386/i386/bus_dma.c
+++ b/sys/arch/i386/i386/bus_dma.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bus_dma.c,v 1.2 2008/12/04 19:25:38 oga Exp $	*/
+/*	$OpenBSD: bus_dma.c,v 1.3 2009/02/05 01:13:21 oga Exp $	*/
 /*-
  * Copyright (c) 1996, 1997 The NetBSD Foundation, Inc.
  * All rights reserved.
@@ -368,7 +368,10 @@ _bus_dmamem_map(bus_dma_tag_t t, bus_dma_segment_t *segs, int nsegs,
 {
 	vaddr_t va;
 	bus_addr_t addr;
-	int curseg;
+	int curseg, pmapflags;
+
+	if (flags & BUS_DMA_NOCACHE)
+		pmapflags |= PMAP_NOCACHE;
 
 	size = round_page(size);
 	va = uvm_km_valloc(kernel_map, size);
@@ -385,7 +388,8 @@ _bus_dmamem_map(bus_dma_tag_t t, bus_dma_segment_t *segs, int nsegs,
 				panic("_bus_dmamem_map: size botch");
 			pmap_enter(pmap_kernel(), va, addr,
 			    VM_PROT_READ | VM_PROT_WRITE,
-			    VM_PROT_READ | VM_PROT_WRITE | PMAP_WIRED);
+			    VM_PROT_READ | VM_PROT_WRITE | PMAP_WIRED |
+			    pmapflags);
 		}
 	}
 	pmap_update(pmap_kernel());
diff --git a/sys/arch/i386/i386/pmap.c b/sys/arch/i386/i386/pmap.c
index 7e3ebfe7cd6..753298eb42a 100644
--- a/sys/arch/i386/i386/pmap.c
+++ b/sys/arch/i386/i386/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.135 2009/01/27 22:14:13 miod Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.136 2009/02/05 01:13:21 oga Exp $	*/
 /*	$NetBSD: pmap.c,v 1.91 2000/06/02 17:46:37 thorpej Exp $	*/
 
 /*
@@ -2591,6 +2591,8 @@ enter_now:
 	pmap_exec_account(pmap, va, opte, npte);
 	if (wired)
 		npte |= PG_W;
+	if (flags & PMAP_NOCACHE)
+		npte |= PG_N;
 	if (va < VM_MAXUSER_ADDRESS)
 		npte |= PG_u;
 	else if (va < VM_MAX_ADDRESS)
diff --git a/sys/arch/i386/include/bus.h b/sys/arch/i386/include/bus.h
index 6a6ccbc933e..eb89149d0dc 100644
--- a/sys/arch/i386/include/bus.h
+++ b/sys/arch/i386/include/bus.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bus.h,v 1.45 2008/12/03 15:46:06 oga Exp $	*/
+/*	$OpenBSD: bus.h,v 1.46 2009/02/05 01:13:21 oga Exp $	*/
 /*	$NetBSD: bus.h,v 1.6 1996/11/10 03:19:25 thorpej Exp $	*/
 
 /*-
@@ -452,6 +452,7 @@ void	bus_space_copy_4(bus_space_tag_t, bus_space_handle_t, bus_size_t,
 #define	BUS_DMA_STREAMING	0x100	/* hint: sequential, unidirectional */
 #define	BUS_DMA_READ		0x200	/* mapping is device -> memory only */
 #define	BUS_DMA_WRITE		0x400	/* mapping is memory -> device only */
+#define	BUS_DMA_NOCACHE		0x800	/* map memory uncached */
 
 /* Forwards needed by prototypes below. */
 struct mbuf;
diff --git a/sys/arch/i386/include/pmap.h b/sys/arch/i386/include/pmap.h
index fa446e6c2a0..89af1a42440 100644
--- a/sys/arch/i386/include/pmap.h
+++ b/sys/arch/i386/include/pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.h,v 1.50 2008/12/18 14:17:28 kurt Exp $	*/
+/*	$OpenBSD: pmap.h,v 1.51 2009/02/05 01:13:21 oga Exp $	*/
 /*	$NetBSD: pmap.h,v 1.44 2000/04/24 17:18:18 thorpej Exp $	*/
 
 /*
@@ -292,6 +292,10 @@ struct pv_entry {			/* locked by its list's pvh_lock */
 	vaddr_t pv_va;			/* the virtual address */
 	struct vm_page *pv_ptp;		/* the vm_page of the PTP */
 };
+/*
+ * MD flags to pmap_enter:
+ */
+#define	PMAP_NOCACHE	PMAP_MD0
 
 /*
  * We keep mod/ref flags in struct vm_page->pg_flags.