- Split the routine to initialize a bus_space_handle into the separate

  function.
- Only access a bus_space_handle if the resource type is SYS_RES_MEMORY or
  SYS_RES_IOPORT.
- Add the bus_space_subregion supports.

9 files changed, 339 insertions, 142 deletions

diff --git a/sys/amd64/amd64/legacy.c b/sys/amd64/amd64/legacy.c
index 07518ad..d4fa131 100644
--- a/sys/amd64/amd64/legacy.c
+++ b/sys/amd64/amd64/legacy.c
@@ -76,9 +76,6 @@
 #include <i386/isa/intr_machdep.h>
 #include <sys/rtprio.h>
 
-#ifdef PC98
-static MALLOC_DEFINE(M_BUSSPACEHANDLE, "busspacehandle", "Bus space handle");
-#endif
 static MALLOC_DEFINE(M_NEXUSDEV, "nexusdev", "Nexus device");
 struct nexus_device {
 	struct resource_list	nx_resources;
@@ -438,40 +435,32 @@ nexus_alloc_resource(device_t bus, device_t child, int type, int *rid,
 	rv = rman_reserve_resource(rm, start, end, count, flags, child);
 	if (rv == 0)
 		return 0;
-#ifdef PC98
-	/* Allocate bushandle. */
-	rv->r_bushandle = malloc(sizeof *rv->r_bushandle, M_BUSSPACEHANDLE,
-				 M_NOWAIT | M_ZERO);
-	if (rv->r_bushandle == 0) {
-		rman_release_resource(rv);
-		return 0;
-	}
-#endif
 
 	if (type == SYS_RES_MEMORY) {
 		rman_set_bustag(rv, I386_BUS_SPACE_MEM);
 	} else if (type == SYS_RES_IOPORT) {
 		rman_set_bustag(rv, I386_BUS_SPACE_IO);
-#ifdef PC98
-		/* PC-98: the type of bus_space_handle_t is the structure. */
-		rv->r_bushandle->bsh_base = rv->r_start;
-		rv->r_bushandle->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
-		rv->r_bushandle->bsh_iatsz = 0;
-		rv->r_bushandle->bsh_res = NULL;
-		rv->r_bushandle->bsh_ressz = 0;
-
-		/* default: direct access */
-		rv->r_bushandle->bsh_bam = rv->r_bustag->bs_da;
-#else
-		/* IBM-PC: the type of bus_space_handle_t is u_int */
+#ifndef PC98
 		rman_set_bushandle(rv, rv->r_start);
 #endif
 	}
 
+#ifdef PC98
+	if ((type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) &&
+	    i386_bus_space_handle_alloc(rv->r_bustag, rv->r_start, count,
+					&rv->r_bushandle) != 0) {
+		rman_release_resource(rv);
+		return 0;
+	}
+#endif
+
 	if (needactivate) {
 		if (bus_activate_resource(child, type, *rid, rv)) {
 #ifdef PC98
-			free(rv->r_bushandle, M_BUSSPACEHANDLE);
+			if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+				i386_bus_space_handle_free(rv->r_bustag,
+				    rv->r_bushandle, rv->r_bushandle->bsh_sz);
+			}
 #endif
 			rman_release_resource(rv);
 			return 0;
@@ -511,13 +500,6 @@ nexus_activate_resource(device_t bus, device_t child, int type, int rid,
 #ifdef PC98
 		/* PC-98: the type of bus_space_handle_t is the structure. */
 		r->r_bushandle->bsh_base = (bus_addr_t) vaddr;
-		r->r_bushandle->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
-		r->r_bushandle->bsh_iatsz = 0;
-		r->r_bushandle->bsh_res = NULL;
-		r->r_bushandle->bsh_ressz = 0;
-
-		/* default: direct access */
-		r->r_bushandle->bsh_bam = r->r_bustag->bs_da;
 #else
 		/* IBM-PC: the type of bus_space_handle_t is u_int */
 		rman_set_bushandle(r, (bus_space_handle_t) vaddr);
@@ -554,7 +536,10 @@ nexus_release_resource(device_t bus, device_t child, int type, int rid,
 			return error;
 	}
 #ifdef PC98
-	free(r->r_bushandle, M_BUSSPACEHANDLE);
+	if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+		i386_bus_space_handle_free(r->r_bustag, r->r_bushandle,
+					   r->r_bushandle->bsh_sz);
+	}
 #endif
 	return (rman_release_resource(r));
 }
diff --git a/sys/amd64/amd64/nexus.c b/sys/amd64/amd64/nexus.c
index 07518ad..d4fa131 100644
--- a/sys/amd64/amd64/nexus.c
+++ b/sys/amd64/amd64/nexus.c
@@ -76,9 +76,6 @@
 #include <i386/isa/intr_machdep.h>
 #include <sys/rtprio.h>
 
-#ifdef PC98
-static MALLOC_DEFINE(M_BUSSPACEHANDLE, "busspacehandle", "Bus space handle");
-#endif
 static MALLOC_DEFINE(M_NEXUSDEV, "nexusdev", "Nexus device");
 struct nexus_device {
 	struct resource_list	nx_resources;
@@ -438,40 +435,32 @@ nexus_alloc_resource(device_t bus, device_t child, int type, int *rid,
 	rv = rman_reserve_resource(rm, start, end, count, flags, child);
 	if (rv == 0)
 		return 0;
-#ifdef PC98
-	/* Allocate bushandle. */
-	rv->r_bushandle = malloc(sizeof *rv->r_bushandle, M_BUSSPACEHANDLE,
-				 M_NOWAIT | M_ZERO);
-	if (rv->r_bushandle == 0) {
-		rman_release_resource(rv);
-		return 0;
-	}
-#endif
 
 	if (type == SYS_RES_MEMORY) {
 		rman_set_bustag(rv, I386_BUS_SPACE_MEM);
 	} else if (type == SYS_RES_IOPORT) {
 		rman_set_bustag(rv, I386_BUS_SPACE_IO);
-#ifdef PC98
-		/* PC-98: the type of bus_space_handle_t is the structure. */
-		rv->r_bushandle->bsh_base = rv->r_start;
-		rv->r_bushandle->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
-		rv->r_bushandle->bsh_iatsz = 0;
-		rv->r_bushandle->bsh_res = NULL;
-		rv->r_bushandle->bsh_ressz = 0;
-
-		/* default: direct access */
-		rv->r_bushandle->bsh_bam = rv->r_bustag->bs_da;
-#else
-		/* IBM-PC: the type of bus_space_handle_t is u_int */
+#ifndef PC98
 		rman_set_bushandle(rv, rv->r_start);
 #endif
 	}
 
+#ifdef PC98
+	if ((type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) &&
+	    i386_bus_space_handle_alloc(rv->r_bustag, rv->r_start, count,
+					&rv->r_bushandle) != 0) {
+		rman_release_resource(rv);
+		return 0;
+	}
+#endif
+
 	if (needactivate) {
 		if (bus_activate_resource(child, type, *rid, rv)) {
 #ifdef PC98
-			free(rv->r_bushandle, M_BUSSPACEHANDLE);
+			if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+				i386_bus_space_handle_free(rv->r_bustag,
+				    rv->r_bushandle, rv->r_bushandle->bsh_sz);
+			}
 #endif
 			rman_release_resource(rv);
 			return 0;
@@ -511,13 +500,6 @@ nexus_activate_resource(device_t bus, device_t child, int type, int rid,
 #ifdef PC98
 		/* PC-98: the type of bus_space_handle_t is the structure. */
 		r->r_bushandle->bsh_base = (bus_addr_t) vaddr;
-		r->r_bushandle->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
-		r->r_bushandle->bsh_iatsz = 0;
-		r->r_bushandle->bsh_res = NULL;
-		r->r_bushandle->bsh_ressz = 0;
-
-		/* default: direct access */
-		r->r_bushandle->bsh_bam = r->r_bustag->bs_da;
 #else
 		/* IBM-PC: the type of bus_space_handle_t is u_int */
 		rman_set_bushandle(r, (bus_space_handle_t) vaddr);
@@ -554,7 +536,10 @@ nexus_release_resource(device_t bus, device_t child, int type, int rid,
 			return error;
 	}
 #ifdef PC98
-	free(r->r_bushandle, M_BUSSPACEHANDLE);
+	if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+		i386_bus_space_handle_free(r->r_bustag, r->r_bushandle,
+					   r->r_bushandle->bsh_sz);
+	}
 #endif
 	return (rman_release_resource(r));
 }
diff --git a/sys/amd64/isa/isa.c b/sys/amd64/isa/isa.c
index 9124c8d..bd1df32 100644
--- a/sys/amd64/isa/isa.c
+++ b/sys/amd64/isa/isa.c
@@ -236,11 +236,13 @@ isa_release_resource(device_t bus, device_t child, int type, int rid,
 	 */
 	int	i;
 
-	for (i = 1; i < r->r_bushandle->bsh_ressz; i++)
-		resource_list_release(rl, bus, child, type, rid + i,
-				      r->r_bushandle->bsh_res[i]);
-	if (r->r_bushandle->bsh_res != NULL)
-		free(r->r_bushandle->bsh_res, M_DEVBUF);
+	if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+		for (i = 1; i < r->r_bushandle->bsh_ressz; i++)
+			resource_list_release(rl, bus, child, type, rid + i,
+					      r->r_bushandle->bsh_res[i]);
+		if (r->r_bushandle->bsh_res != NULL)
+			free(r->r_bushandle->bsh_res, M_DEVBUF);
+	}
 #endif
 	return resource_list_release(rl, bus, child, type, rid, r);
 }
diff --git a/sys/i386/i386/legacy.c b/sys/i386/i386/legacy.c
index 07518ad..d4fa131 100644
--- a/sys/i386/i386/legacy.c
+++ b/sys/i386/i386/legacy.c
@@ -76,9 +76,6 @@
 #include <i386/isa/intr_machdep.h>
 #include <sys/rtprio.h>
 
-#ifdef PC98
-static MALLOC_DEFINE(M_BUSSPACEHANDLE, "busspacehandle", "Bus space handle");
-#endif
 static MALLOC_DEFINE(M_NEXUSDEV, "nexusdev", "Nexus device");
 struct nexus_device {
 	struct resource_list	nx_resources;
@@ -438,40 +435,32 @@ nexus_alloc_resource(device_t bus, device_t child, int type, int *rid,
 	rv = rman_reserve_resource(rm, start, end, count, flags, child);
 	if (rv == 0)
 		return 0;
-#ifdef PC98
-	/* Allocate bushandle. */
-	rv->r_bushandle = malloc(sizeof *rv->r_bushandle, M_BUSSPACEHANDLE,
-				 M_NOWAIT | M_ZERO);
-	if (rv->r_bushandle == 0) {
-		rman_release_resource(rv);
-		return 0;
-	}
-#endif
 
 	if (type == SYS_RES_MEMORY) {
 		rman_set_bustag(rv, I386_BUS_SPACE_MEM);
 	} else if (type == SYS_RES_IOPORT) {
 		rman_set_bustag(rv, I386_BUS_SPACE_IO);
-#ifdef PC98
-		/* PC-98: the type of bus_space_handle_t is the structure. */
-		rv->r_bushandle->bsh_base = rv->r_start;
-		rv->r_bushandle->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
-		rv->r_bushandle->bsh_iatsz = 0;
-		rv->r_bushandle->bsh_res = NULL;
-		rv->r_bushandle->bsh_ressz = 0;
-
-		/* default: direct access */
-		rv->r_bushandle->bsh_bam = rv->r_bustag->bs_da;
-#else
-		/* IBM-PC: the type of bus_space_handle_t is u_int */
+#ifndef PC98
 		rman_set_bushandle(rv, rv->r_start);
 #endif
 	}
 
+#ifdef PC98
+	if ((type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) &&
+	    i386_bus_space_handle_alloc(rv->r_bustag, rv->r_start, count,
+					&rv->r_bushandle) != 0) {
+		rman_release_resource(rv);
+		return 0;
+	}
+#endif
+
 	if (needactivate) {
 		if (bus_activate_resource(child, type, *rid, rv)) {
 #ifdef PC98
-			free(rv->r_bushandle, M_BUSSPACEHANDLE);
+			if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+				i386_bus_space_handle_free(rv->r_bustag,
+				    rv->r_bushandle, rv->r_bushandle->bsh_sz);
+			}
 #endif
 			rman_release_resource(rv);
 			return 0;
@@ -511,13 +500,6 @@ nexus_activate_resource(device_t bus, device_t child, int type, int rid,
 #ifdef PC98
 		/* PC-98: the type of bus_space_handle_t is the structure. */
 		r->r_bushandle->bsh_base = (bus_addr_t) vaddr;
-		r->r_bushandle->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
-		r->r_bushandle->bsh_iatsz = 0;
-		r->r_bushandle->bsh_res = NULL;
-		r->r_bushandle->bsh_ressz = 0;
-
-		/* default: direct access */
-		r->r_bushandle->bsh_bam = r->r_bustag->bs_da;
 #else
 		/* IBM-PC: the type of bus_space_handle_t is u_int */
 		rman_set_bushandle(r, (bus_space_handle_t) vaddr);
@@ -554,7 +536,10 @@ nexus_release_resource(device_t bus, device_t child, int type, int rid,
 			return error;
 	}
 #ifdef PC98
-	free(r->r_bushandle, M_BUSSPACEHANDLE);
+	if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+		i386_bus_space_handle_free(r->r_bustag, r->r_bushandle,
+					   r->r_bushandle->bsh_sz);
+	}
 #endif
 	return (rman_release_resource(r));
 }
diff --git a/sys/i386/i386/nexus.c b/sys/i386/i386/nexus.c
index 07518ad..d4fa131 100644
--- a/sys/i386/i386/nexus.c
+++ b/sys/i386/i386/nexus.c
@@ -76,9 +76,6 @@
 #include <i386/isa/intr_machdep.h>
 #include <sys/rtprio.h>
 
-#ifdef PC98
-static MALLOC_DEFINE(M_BUSSPACEHANDLE, "busspacehandle", "Bus space handle");
-#endif
 static MALLOC_DEFINE(M_NEXUSDEV, "nexusdev", "Nexus device");
 struct nexus_device {
 	struct resource_list	nx_resources;
@@ -438,40 +435,32 @@ nexus_alloc_resource(device_t bus, device_t child, int type, int *rid,
 	rv = rman_reserve_resource(rm, start, end, count, flags, child);
 	if (rv == 0)
 		return 0;
-#ifdef PC98
-	/* Allocate bushandle. */
-	rv->r_bushandle = malloc(sizeof *rv->r_bushandle, M_BUSSPACEHANDLE,
-				 M_NOWAIT | M_ZERO);
-	if (rv->r_bushandle == 0) {
-		rman_release_resource(rv);
-		return 0;
-	}
-#endif
 
 	if (type == SYS_RES_MEMORY) {
 		rman_set_bustag(rv, I386_BUS_SPACE_MEM);
 	} else if (type == SYS_RES_IOPORT) {
 		rman_set_bustag(rv, I386_BUS_SPACE_IO);
-#ifdef PC98
-		/* PC-98: the type of bus_space_handle_t is the structure. */
-		rv->r_bushandle->bsh_base = rv->r_start;
-		rv->r_bushandle->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
-		rv->r_bushandle->bsh_iatsz = 0;
-		rv->r_bushandle->bsh_res = NULL;
-		rv->r_bushandle->bsh_ressz = 0;
-
-		/* default: direct access */
-		rv->r_bushandle->bsh_bam = rv->r_bustag->bs_da;
-#else
-		/* IBM-PC: the type of bus_space_handle_t is u_int */
+#ifndef PC98
 		rman_set_bushandle(rv, rv->r_start);
 #endif
 	}
 
+#ifdef PC98
+	if ((type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) &&
+	    i386_bus_space_handle_alloc(rv->r_bustag, rv->r_start, count,
+					&rv->r_bushandle) != 0) {
+		rman_release_resource(rv);
+		return 0;
+	}
+#endif
+
 	if (needactivate) {
 		if (bus_activate_resource(child, type, *rid, rv)) {
 #ifdef PC98
-			free(rv->r_bushandle, M_BUSSPACEHANDLE);
+			if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+				i386_bus_space_handle_free(rv->r_bustag,
+				    rv->r_bushandle, rv->r_bushandle->bsh_sz);
+			}
 #endif
 			rman_release_resource(rv);
 			return 0;
@@ -511,13 +500,6 @@ nexus_activate_resource(device_t bus, device_t child, int type, int rid,
 #ifdef PC98
 		/* PC-98: the type of bus_space_handle_t is the structure. */
 		r->r_bushandle->bsh_base = (bus_addr_t) vaddr;
-		r->r_bushandle->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
-		r->r_bushandle->bsh_iatsz = 0;
-		r->r_bushandle->bsh_res = NULL;
-		r->r_bushandle->bsh_ressz = 0;
-
-		/* default: direct access */
-		r->r_bushandle->bsh_bam = r->r_bustag->bs_da;
 #else
 		/* IBM-PC: the type of bus_space_handle_t is u_int */
 		rman_set_bushandle(r, (bus_space_handle_t) vaddr);
@@ -554,7 +536,10 @@ nexus_release_resource(device_t bus, device_t child, int type, int rid,
 			return error;
 	}
 #ifdef PC98
-	free(r->r_bushandle, M_BUSSPACEHANDLE);
+	if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+		i386_bus_space_handle_free(r->r_bustag, r->r_bushandle,
+					   r->r_bushandle->bsh_sz);
+	}
 #endif
 	return (rman_release_resource(r));
 }
diff --git a/sys/i386/include/bus_pc98.h b/sys/i386/include/bus_pc98.h
index 99ac7a8..e1ab78f 100644
--- a/sys/i386/include/bus_pc98.h
+++ b/sys/i386/include/bus_pc98.h
@@ -148,6 +148,8 @@ extern struct bus_space_tag SBUS_mem_space_tag;
  */
 struct bus_space_handle {
 	bus_addr_t	bsh_base;
+	size_t		bsh_sz;
+
 	bus_addr_t	bsh_iat[BUS_SPACE_IAT_MAXSIZE];
 	size_t		bsh_maxiatsz;
 	size_t		bsh_iatsz;
@@ -160,6 +162,29 @@ struct bus_space_handle {
 typedef struct bus_space_handle *bus_space_handle_t;
 
 /*
+ * Allocate/Free bus_space_handle
+ */
+int i386_bus_space_handle_alloc(bus_space_tag_t t, bus_addr_t bpa,
+				bus_size_t size, bus_space_handle_t *bshp);
+void i386_bus_space_handle_free(bus_space_tag_t t, bus_space_handle_t bsh,
+				size_t size);
+
+/*
+ *      int bus_space_subregion (bus_space_tag_t t,
+ *          bus_space_handle_t bsh, bus_size_t offset, bus_size_t size,
+ *          bus_space_handle_t *nbshp);
+ *
+ * Get a new handle for a subregion of an already-mapped area of bus space.
+ */
+
+int i386_memio_subregion(bus_space_tag_t t, bus_space_handle_t bsh,
+			 bus_size_t offset, bus_size_t size,
+			 bus_space_handle_t *nbshp);
+
+#define bus_space_subregion(t, h, o, s, nhp)				\
+	i386_memio_subregion((t), (h), (o), (s), (nhp))
+
+/*
  * Access methods for bus resources and address space.
  */
 #define	_BUS_ACCESS_METHODS_PROTO(TYPE,BWN) \
diff --git a/sys/i386/isa/isa.c b/sys/i386/isa/isa.c
index 9124c8d..bd1df32 100644
--- a/sys/i386/isa/isa.c
+++ b/sys/i386/isa/isa.c
@@ -236,11 +236,13 @@ isa_release_resource(device_t bus, device_t child, int type, int rid,
 	 */
 	int	i;
 
-	for (i = 1; i < r->r_bushandle->bsh_ressz; i++)
-		resource_list_release(rl, bus, child, type, rid + i,
-				      r->r_bushandle->bsh_res[i]);
-	if (r->r_bushandle->bsh_res != NULL)
-		free(r->r_bushandle->bsh_res, M_DEVBUF);
+	if (type == SYS_RES_MEMORY || type == SYS_RES_IOPORT) {
+		for (i = 1; i < r->r_bushandle->bsh_ressz; i++)
+			resource_list_release(rl, bus, child, type, rid + i,
+					      r->r_bushandle->bsh_res[i]);
+		if (r->r_bushandle->bsh_res != NULL)
+			free(r->r_bushandle->bsh_res, M_DEVBUF);
+	}
 #endif
 	return resource_list_release(rl, bus, child, type, rid, r);
 }
diff --git a/sys/pc98/i386/busiosubr.c b/sys/pc98/i386/busiosubr.c
index c2c6228..4df0c1b 100644
--- a/sys/pc98/i386/busiosubr.c
+++ b/sys/pc98/i386/busiosubr.c
@@ -43,8 +43,11 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
+#include <sys/malloc.h>
 #include <machine/bus.h>
 
+static MALLOC_DEFINE(M_BUSSPACEHANDLE, "busspacehandle", "Bus space handle");
+
 _BUS_SPACE_CALL_FUNCS_PROTO(SBUS_DA_io,u_int8_t,1)
 _BUS_SPACE_CALL_FUNCS_PROTO(SBUS_DA_io,u_int16_t,2)
 _BUS_SPACE_CALL_FUNCS_PROTO(SBUS_DA_io,u_int32_t,4)
@@ -142,3 +145,114 @@ struct bus_space_tag NEPC_mem_space_tag = {
 };
 
 #endif /* DEV_MECIA */
+
+/*************************************************************************
+ * map init
+ *************************************************************************/
+static __inline void
+bus_space_iat_init(bus_space_handle_t bsh)
+{
+	int i;
+
+	for (i = 0; i < bsh->bsh_maxiatsz; i++)
+		bsh->bsh_iat[i] = bsh->bsh_base + i;
+}
+
+/*************************************************************************
+ * handle allocation
+ *************************************************************************/
+int
+i386_bus_space_handle_alloc(bus_space_tag_t t, bus_addr_t bpa, bus_size_t size,
+			    bus_space_handle_t *bshp)
+{
+	bus_space_handle_t bsh;
+
+	bsh = (bus_space_handle_t) malloc(sizeof (*bsh), M_BUSSPACEHANDLE,
+					  M_NOWAIT | M_ZERO);
+	if (bsh == NULL)
+		return ENOMEM;
+
+	bsh->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
+	bsh->bsh_iatsz = 0;
+	bsh->bsh_base = bpa;
+	bsh->bsh_sz = size;
+	bsh->bsh_res = NULL;
+	bsh->bsh_ressz = 0;
+	bus_space_iat_init(bsh);
+
+	bsh->bsh_bam = t->bs_da;		/* default: direct access */
+
+	*bshp = bsh;
+	return 0;
+}
+
+void
+i386_bus_space_handle_free(bus_space_tag_t t, bus_space_handle_t bsh,
+			   size_t size)
+{
+
+	free(bsh, M_BUSSPACEHANDLE);
+}
+
+/*************************************************************************
+ * map
+ *************************************************************************/
+int
+i386_memio_subregion(bus_space_tag_t t, bus_space_handle_t pbsh,
+		     bus_size_t offset, bus_size_t size,
+		     bus_space_handle_t *tbshp)
+{
+	int i, error = 0;
+	bus_space_handle_t bsh;
+	bus_addr_t pbase;
+
+	pbase = pbsh->bsh_base + offset;
+	switch (t->bs_tag) {
+	case BUS_SPACE_IO:
+		if (pbsh->bsh_iatsz > 0) {
+			if (offset >= pbsh->bsh_iatsz || 
+			    offset + size > pbsh->bsh_iatsz)
+				return EINVAL;
+			pbase = pbsh->bsh_base;
+		}
+		break;
+
+	case BUS_SPACE_MEM:
+		if (pbsh->bsh_iatsz > 0)
+			return EINVAL;
+		if (offset > pbsh->bsh_sz || offset + size > pbsh->bsh_sz)
+			return EINVAL;
+		break;
+
+	default:
+		panic("i386_memio_subregion: bad bus space tag");
+		break;
+	}
+
+	error = i386_bus_space_handle_alloc(t, pbase, size, &bsh);
+	if (error != 0)
+		return error;
+
+	switch (t->bs_tag) {
+	case BUS_SPACE_IO:
+		if (pbsh->bsh_iatsz > 0) {
+			for (i = 0; i < size; i ++)
+				bsh->bsh_iat[i] = pbsh->bsh_iat[i + offset];
+			bsh->bsh_iatsz = size;
+		} else if (pbsh->bsh_base > bsh->bsh_base ||
+		         pbsh->bsh_base + pbsh->bsh_sz <
+		         bsh->bsh_base + bsh->bsh_sz) {
+			i386_bus_space_handle_free(t, bsh, size);
+			return EINVAL;
+		}
+		break;
+
+	case BUS_SPACE_MEM:
+		break;
+	}
+
+	if (pbsh->bsh_iatsz > 0)
+		bsh->bsh_bam = t->bs_ra;	/* relocate access */
+	*tbshp = bsh;
+	return error;
+}
diff --git a/sys/pc98/pc98/busiosubr.c b/sys/pc98/pc98/busiosubr.c
index c2c6228..4df0c1b 100644
--- a/sys/pc98/pc98/busiosubr.c
+++ b/sys/pc98/pc98/busiosubr.c
@@ -43,8 +43,11 @@
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/kernel.h>
+#include <sys/malloc.h>
 #include <machine/bus.h>
 
+static MALLOC_DEFINE(M_BUSSPACEHANDLE, "busspacehandle", "Bus space handle");
+
 _BUS_SPACE_CALL_FUNCS_PROTO(SBUS_DA_io,u_int8_t,1)
 _BUS_SPACE_CALL_FUNCS_PROTO(SBUS_DA_io,u_int16_t,2)
 _BUS_SPACE_CALL_FUNCS_PROTO(SBUS_DA_io,u_int32_t,4)
@@ -142,3 +145,114 @@ struct bus_space_tag NEPC_mem_space_tag = {
 };
 
 #endif /* DEV_MECIA */
+
+/*************************************************************************
+ * map init
+ *************************************************************************/
+static __inline void
+bus_space_iat_init(bus_space_handle_t bsh)
+{
+	int i;
+
+	for (i = 0; i < bsh->bsh_maxiatsz; i++)
+		bsh->bsh_iat[i] = bsh->bsh_base + i;
+}
+
+/*************************************************************************
+ * handle allocation
+ *************************************************************************/
+int
+i386_bus_space_handle_alloc(bus_space_tag_t t, bus_addr_t bpa, bus_size_t size,
+			    bus_space_handle_t *bshp)
+{
+	bus_space_handle_t bsh;
+
+	bsh = (bus_space_handle_t) malloc(sizeof (*bsh), M_BUSSPACEHANDLE,
+					  M_NOWAIT | M_ZERO);
+	if (bsh == NULL)
+		return ENOMEM;
+
+	bsh->bsh_maxiatsz = BUS_SPACE_IAT_MAXSIZE;
+	bsh->bsh_iatsz = 0;
+	bsh->bsh_base = bpa;
+	bsh->bsh_sz = size;
+	bsh->bsh_res = NULL;
+	bsh->bsh_ressz = 0;
+	bus_space_iat_init(bsh);
+
+	bsh->bsh_bam = t->bs_da;		/* default: direct access */
+
+	*bshp = bsh;
+	return 0;
+}
+
+void
+i386_bus_space_handle_free(bus_space_tag_t t, bus_space_handle_t bsh,
+			   size_t size)
+{
+
+	free(bsh, M_BUSSPACEHANDLE);
+}
+
+/*************************************************************************
+ * map
+ *************************************************************************/
+int
+i386_memio_subregion(bus_space_tag_t t, bus_space_handle_t pbsh,
+		     bus_size_t offset, bus_size_t size,
+		     bus_space_handle_t *tbshp)
+{
+	int i, error = 0;
+	bus_space_handle_t bsh;
+	bus_addr_t pbase;
+
+	pbase = pbsh->bsh_base + offset;
+	switch (t->bs_tag) {
+	case BUS_SPACE_IO:
+		if (pbsh->bsh_iatsz > 0) {
+			if (offset >= pbsh->bsh_iatsz || 
+			    offset + size > pbsh->bsh_iatsz)
+				return EINVAL;
+			pbase = pbsh->bsh_base;
+		}
+		break;
+
+	case BUS_SPACE_MEM:
+		if (pbsh->bsh_iatsz > 0)
+			return EINVAL;
+		if (offset > pbsh->bsh_sz || offset + size > pbsh->bsh_sz)
+			return EINVAL;
+		break;
+
+	default:
+		panic("i386_memio_subregion: bad bus space tag");
+		break;
+	}
+
+	error = i386_bus_space_handle_alloc(t, pbase, size, &bsh);
+	if (error != 0)
+		return error;
+
+	switch (t->bs_tag) {
+	case BUS_SPACE_IO:
+		if (pbsh->bsh_iatsz > 0) {
+			for (i = 0; i < size; i ++)
+				bsh->bsh_iat[i] = pbsh->bsh_iat[i + offset];
+			bsh->bsh_iatsz = size;
+		} else if (pbsh->bsh_base > bsh->bsh_base ||
+		         pbsh->bsh_base + pbsh->bsh_sz <
+		         bsh->bsh_base + bsh->bsh_sz) {
+			i386_bus_space_handle_free(t, bsh, size);
+			return EINVAL;
+		}
+		break;
+
+	case BUS_SPACE_MEM:
+		break;
+	}
+
+	if (pbsh->bsh_iatsz > 0)
+		bsh->bsh_bam = t->bs_ra;	/* relocate access */
+	*tbshp = bsh;
+	return error;
+}