First draft of common code between pccbb and pcic drivers for talking

to ExCA register sets.  These registers exist in both ISA and PCI
devices in a couple different ways, and this will provide a common
base for future building.  This code is a rehash of the pccbb 16-bit
code, which was a rehash of the pcic code, which was a rehash of the
netbsd i82365 code.  More hashing to come.

1 files changed, 617 insertions, 0 deletions

diff --git a/sys/dev/exca/exca.c b/sys/dev/exca/exca.c
new file mode 100644
index 0000000..52e3da2
--- /dev/null
+++ b/sys/dev/exca/exca.c
@@ -0,0 +1,617 @@
+/* $FreeBSD$ */
+
+/*
+ * Copyright (c) 2002 M Warner Losh.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software may be derived from NetBSD i82365.c and other files with
+ * the following copyright:
+ *
+ * Copyright (c) 1997 Marc Horowitz.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by Marc Horowitz.
+ * 4. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/errno.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+#include <sys/queue.h>
+
+#include <sys/bus.h>
+#include <machine/bus.h>
+#include <sys/rman.h>
+#include <machine/resource.h>
+
+#include <dev/pccard/pccardreg.h>
+#include <dev/pccard/pccardvar.h>
+
+#include <dev/exca/excareg.h>
+#include <dev/exca/excavar.h>
+
+#define EXCA_DEBUG
+#ifdef EXCA_DEBUG
+#define DEVPRINTF(dev, fmt, args...)	device_printf((dev), (fmt), ## args)
+#define DPRINTF(fmt, args...)		printf(fmt, ## args)
+#else
+#define DEVPRINTF(dev, fmt, args...)
+#define DPRINTF(fmt, args...)
+#endif
+
+
+/* memory */
+
+#define	EXCA_MEMINFO(NUM) {						\
+	EXCA_SYSMEM_ADDR ## NUM ## _START_LSB,				\
+	EXCA_SYSMEM_ADDR ## NUM ## _START_MSB,				\
+	EXCA_SYSMEM_ADDR ## NUM ## _STOP_LSB,				\
+	EXCA_SYSMEM_ADDR ## NUM ## _STOP_MSB,				\
+	EXCA_SYSMEM_ADDR ## NUM ## _WIN,				\
+	EXCA_CARDMEM_ADDR ## NUM ## _LSB,				\
+	EXCA_CARDMEM_ADDR ## NUM ## _MSB,				\
+	EXCA_ADDRWIN_ENABLE_MEM ## NUM ##,				\
+}
+
+static struct mem_map_index_st {
+	int	sysmem_start_lsb;
+	int	sysmem_start_msb;
+	int	sysmem_stop_lsb;
+	int	sysmem_stop_msb;
+	int	sysmem_win;
+	int	cardmem_lsb;
+	int	cardmem_msb;
+	int	memenable;
+} mem_map_index[] = {
+	EXCA_MEMINFO(0),
+	EXCA_MEMINFO(1),
+	EXCA_MEMINFO(2),
+	EXCA_MEMINFO(3),
+	EXCA_MEMINFO(4)
+};
+#undef	EXCA_MEMINFO
+
+/*
+ * Helper function.  This will map the requested memory slot.  We setup the
+ * map before we call this function.  This is used to initially force the
+ * mapping, as well as later restore the mapping after it has been destroyed
+ * in some fashion (due to a power event typically).
+ */
+static void
+exca_do_mem_map(struct exca_softc *sc, int win)
+{
+	struct mem_map_index_st *map;
+	struct pccard_mem_handle *mem;
+	
+	map = &mem_map_index[win];
+	mem = &sc->mem[win];
+	exca_write(sc, map->sysmem_start_lsb,
+	    (mem->addr >> EXCA_SYSMEM_ADDRX_SHIFT) & 0xff);
+	exca_write(sc, map->sysmem_start_msb,
+	    ((mem->addr >> (EXCA_SYSMEM_ADDRX_SHIFT + 8)) &
+	    EXCA_SYSMEM_ADDRX_START_MSB_ADDR_MASK) | 0x80);
+
+	exca_write(sc, map->sysmem_stop_lsb,
+	    ((mem->addr + mem->realsize - 1) >>
+	    EXCA_SYSMEM_ADDRX_SHIFT) & 0xff);
+	exca_write(sc, map->sysmem_stop_msb,
+	    (((mem->addr + mem->realsize - 1) >>
+	    (EXCA_SYSMEM_ADDRX_SHIFT + 8)) &
+	    EXCA_SYSMEM_ADDRX_STOP_MSB_ADDR_MASK) |
+	    EXCA_SYSMEM_ADDRX_STOP_MSB_WAIT2);
+
+	exca_write(sc, map->sysmem_win,
+	    (mem->addr >> EXCA_MEMREG_WIN_SHIFT) & 0xff);
+
+	exca_write(sc, map->cardmem_lsb,
+	    (mem->offset >> EXCA_CARDMEM_ADDRX_SHIFT) & 0xff);
+	exca_write(sc, map->cardmem_msb,
+	    ((mem->offset >> (EXCA_CARDMEM_ADDRX_SHIFT + 8)) &
+	    EXCA_CARDMEM_ADDRX_MSB_ADDR_MASK) |
+	    ((mem->kind == PCCARD_MEM_ATTR) ?
+	    EXCA_CARDMEM_ADDRX_MSB_REGACTIVE_ATTR : 0));
+
+	exca_setb(sc, EXCA_ADDRWIN_ENABLE, EXCA_ADDRWIN_ENABLE_MEMCS16 |
+	    map->memenable);
+
+	DELAY(100);
+#ifdef EXCA_DEBUG
+	{
+		int r1, r2, r3, r4, r5, r6, r7;
+		r1 = exca_read(sc, map->sysmem_start_msb);
+		r2 = exca_read(sc, map->sysmem_start_lsb);
+		r3 = exca_read(sc, map->sysmem_stop_msb);
+		r4 = exca_read(sc, map->sysmem_stop_lsb);
+		r5 = exca_read(sc, map->cardmem_msb);
+		r6 = exca_read(sc, map->cardmem_lsb);
+		r7 = exca_read(sc, map->sysmem_win);
+		printf("exca_do_mem_map window %d: %02x%02x %02x%02x "
+		    "%02x%02x %02x (%08x+%08x.%08x*%08lx)\n",
+		    win, r1, r2, r3, r4, r5, r6, r7,
+		    mem->addr, mem->size, mem->realsize,
+		    mem->offset);
+	}
+#endif
+}
+
+/*
+ * public interface to map a resource.  kind is the type of memory to
+ * map (either common or attribute).  Memory created via this interface
+ * starts out at card address 0.  Since the only way to set this is
+ * to set it on a struct resource after it has been mapped, we're safe
+ * in maping this assumption.  Note that resources can be remapped using
+ * exca_do_mem_map so that's how the card address can be set later.
+ */
+int
+exca_mem_map(struct exca_softc *sc, int kind, struct resource *res)
+{
+	int win;
+
+	for (win = 0; win < EXCA_MEM_WINS; win++) {
+		if ((sc->memalloc & (1 << win)) == 0) {
+			sc->memalloc |= (1 << win);
+			break;
+		}
+	}
+	if (win >= EXCA_MEM_WINS)
+		return (1);
+
+	sc->mem[win].cardaddr = 0;
+	sc->mem[win].memt = rman_get_bustag(res);
+	sc->mem[win].memh = rman_get_bushandle(res);
+	sc->mem[win].addr = rman_get_start(res);
+	sc->mem[win].size = rman_get_end(res) - sc->mem[win].addr + 1;
+	sc->mem[win].realsize = sc->mem[win].size + EXCA_MEM_PAGESIZE - 1;
+	sc->mem[win].realsize = sc->mem[win].realsize -
+	    (sc->mem[win].realsize % EXCA_MEM_PAGESIZE);
+	sc->mem[win].offset = (long)(sc->mem[win].addr);
+	sc->mem[win].kind = kind;
+	DPRINTF("exca_mem_map window %d bus %x+%x+%lx card addr %x\n",
+	    win, sc->mem[win].addr, sc->mem[win].size,
+	    sc->mem[win].offset, sc->mem[win].cardaddr);
+	exca_do_mem_map(sc, win);
+
+	return (0);
+}
+
+/*
+ * Private helper function.  This turns off a given memory map that is in
+ * use.  We do this by just clearing the enable bit in the pcic.  If we needed
+ * to make memory unmapping/mapping pairs faster, we would have to store
+ * more state information about the pcic and then use that to intelligently
+ * to the map/unmap.  However, since we don't do that sort of thing often
+ * (generally just at configure time), it isn't a case worth optimizing.
+ */
+static void
+exca_mem_unmap(struct exca_softc *sc, int window)
+{
+	if (window < 0 || window >= EXCA_MEM_WINS)
+		panic("exca_mem_unmap: window out of range");
+
+	exca_clrb(sc, EXCA_ADDRWIN_ENABLE, mem_map_index[window].memenable);
+	sc->memalloc &= ~(1 << window);
+}
+
+/*
+ * Find the map that we're using to hold the resoruce.  This works well
+ * so long as the client drivers don't do silly things like map the same
+ * area mutliple times, or map both common and attribute memory at the
+ * same time.  This latter restriction is a bug.  We likely should just
+ * store a pointer to the res in the mem[x] data structure.
+ */
+static int
+exca_mem_findmap(struct exca_softc *sc, struct resource *res)
+{
+	int win;
+
+	for (win = 0; win < EXCA_MEM_WINS; win++) {
+		if (sc->mem[win].memt == rman_get_bustag(res) &&
+		    sc->mem[win].addr == rman_get_start(res) &&
+		    sc->mem[win].size == rman_get_size(res))
+			return (win);
+	}
+	return (-1);
+}
+
+/*
+ * Set the memory flag.  This means that we are setting if the memory
+ * is coming from attribute memory or from common memory on the card.
+ * CIS entries are generally in attribute memory (although they can
+ * reside in common memory).  Generally, this is the only use for attribute
+ * memory.  However, some cards require their drivers to dance in both
+ * common and/or attribute memory and this interface (and setting the
+ * offset interface) exist for such cards.
+ */
+int
+exca_mem_set_flags(struct exca_softc *sc, struct resource *res, uint32_t flags)
+{
+	int win;
+
+	win = exca_mem_findmap(sc, res);
+	if (win < 0) {
+		device_printf(sc->dev,
+		    "set_res_flags: specified resource not active\n");
+		return (ENOENT);
+	}
+
+	sc->mem[win].kind = flags;
+	exca_do_mem_map(sc, win);
+	return (0);
+}
+
+/*
+ * Given a resource, go ahead and unmap it if we can find it in the
+ * resrouce list that's used.
+ */
+int
+exca_mem_unmap_res(struct exca_softc *sc, struct resource *res)
+{
+	int win;
+
+	win = exca_mem_findmap(sc, res);
+	if (win < 0)
+		return (ENOENT);
+	exca_mem_unmap(sc, win);
+	return (0);
+}
+	
+/*
+ * Set the offset of the memory.  We use this for reading the CIS and
+ * frobbing the pccard's pccard registers (POR, etc).  Some drivers
+ * need to access this functionality as well, since they have receive
+ * buffers defined in the attribute memory.  Thankfully, these cards
+ * are few and fare between.  Some cards also have common memory that
+ * is large and only map a small portion of it at a time (but these cards
+ * are rare, the more common case being to have just a small amount
+ * of common memory that the driver needs to bcopy data from in order to
+ * get at it.
+ */
+int
+exca_mem_set_offset(struct exca_softc *sc, struct resource *res,
+    uint32_t cardaddr, uint32_t *deltap)
+{
+	int win;
+	uint32_t delta;
+
+	win = exca_mem_findmap(sc, res);
+	if (win < 0) {
+		device_printf(sc->dev,
+		    "set_memory_offset: specified resource not active\n");
+		return (ENOENT);
+	}
+	sc->mem[win].cardaddr = cardaddr;
+	delta = cardaddr % EXCA_MEM_PAGESIZE;
+	if (deltap)
+		*deltap = delta;
+	cardaddr -= delta;
+	sc->mem[win].realsize = sc->mem[win].size + delta +
+	    EXCA_MEM_PAGESIZE - 1;
+	sc->mem[win].realsize = sc->mem[win].realsize -
+	    (sc->mem[win].realsize % EXCA_MEM_PAGESIZE);
+	sc->mem[win].offset = cardaddr - sc->mem[win].addr;
+	exca_do_mem_map(sc, win);
+	return (0);
+}
+			
+
+/* I/O */
+
+#define	EXCA_IOINFO(NUM) {						\
+	EXCA_IOADDR ## NUM ## _START_LSB,				\
+	EXCA_IOADDR ## NUM ## _START_MSB,				\
+	EXCA_IOADDR ## NUM ## _STOP_LSB,				\
+	EXCA_IOADDR ## NUM ## _STOP_MSB,				\
+	EXCA_ADDRWIN_ENABLE_IO ## NUM ##,				\
+	EXCA_IOCTL_IO ## NUM ## _WAITSTATE				\
+	| EXCA_IOCTL_IO ## NUM ## _ZEROWAIT				\
+	| EXCA_IOCTL_IO ## NUM ## _IOCS16SRC_MASK			\
+	| EXCA_IOCTL_IO ## NUM ## _DATASIZE_MASK,			\
+	{								\
+		EXCA_IOCTL_IO ## NUM ## _IOCS16SRC_CARD,		\
+		EXCA_IOCTL_IO ## NUM ## _IOCS16SRC_DATASIZE		\
+		| EXCA_IOCTL_IO ## NUM ## _DATASIZE_8BIT,		\
+		EXCA_IOCTL_IO ## NUM ## _IOCS16SRC_DATASIZE		\
+		| EXCA_IOCTL_IO ## NUM ## _DATASIZE_16BIT,		\
+	}								\
+}
+
+static struct io_map_index_st {
+	int	start_lsb;
+	int	start_msb;
+	int	stop_lsb;
+	int	stop_msb;
+	int	ioenable;
+	int	ioctlmask;
+	int	ioctlbits[3]; /* indexed by PCCARD_WIDTH_* */
+} io_map_index[] = {
+	EXCA_IOINFO(0),
+	EXCA_IOINFO(1),
+};
+#undef	EXCA_IOINFO
+
+static void
+exca_do_io_map(struct exca_softc *sc, int win)
+{
+	struct io_map_index_st *map;
+
+	struct pccard_io_handle *io;
+
+	map = &io_map_index[win];
+	io = &sc->io[win];
+	exca_write(sc, map->start_lsb, io->addr & 0xff);
+	exca_write(sc, map->start_msb, (io->addr >> 8) & 0xff);
+
+	exca_write(sc, map->stop_lsb, (io->addr + io->size - 1) & 0xff);
+	exca_write(sc, map->stop_msb, ((io->addr + io->size - 1) >> 8) & 0xff);
+
+	exca_clrb(sc, EXCA_IOCTL, map->ioctlmask);
+	exca_setb(sc, EXCA_IOCTL, map->ioctlbits[io->width]);
+
+	exca_setb(sc, EXCA_ADDRWIN_ENABLE, map->ioenable);
+#ifdef EXCA_DEBUG
+	{
+		int r1, r2, r3, r4;
+		r1 = exca_read(sc, map->start_msb);
+		r2 = exca_read(sc, map->start_lsb);
+		r3 = exca_read(sc, map->stop_msb);
+		r4 = exca_read(sc, map->stop_lsb);
+		DPRINTF("exca_do_io_map window %d: %02x%02x %02x%02x "
+		    "(%08x+%08x)\n", win, r1, r2, r3, r4,
+		    io->addr, io->size);
+	}
+#endif
+}
+
+int
+exca_io_map(struct exca_softc *sc, int width, struct resource *r)
+{
+	int win;
+#ifdef EXCA_DEBUG
+	static char *width_names[] = { "auto", "io8", "io16"};
+#endif
+	for (win=0; win < EXCA_IO_WINS; win++) {
+		if ((sc->ioalloc & (1 << win)) == 0) {
+			sc->ioalloc |= (1 << win);
+			break;
+		}
+	}
+	if (win >= EXCA_IO_WINS)
+		return (1);
+
+	sc->io[win].iot = rman_get_bustag(r);
+	sc->io[win].ioh = rman_get_bushandle(r);
+	sc->io[win].addr = rman_get_start(r);
+	sc->io[win].size = rman_get_end(r) - sc->io[win].addr + 1;
+	sc->io[win].flags = 0;
+	sc->io[win].width = width;
+	DPRINTF("exca_io_map window %d %s port %x+%x\n",
+	    win, width_names[width], sc->io[win].addr,
+	    sc->io[win].size);
+	exca_do_io_map(sc, win);
+
+	return (0);
+}
+
+static void
+exca_io_unmap(struct exca_softc *sc, int window)
+{
+	if (window >= EXCA_IO_WINS)
+		panic("exca_io_unmap: window out of range");
+
+	exca_clrb(sc, EXCA_ADDRWIN_ENABLE, io_map_index[window].ioenable);
+
+	sc->ioalloc &= ~(1 << window);
+
+	sc->io[window].iot = 0;
+	sc->io[window].ioh = 0;
+	sc->io[window].addr = 0;
+	sc->io[window].size = 0;
+	sc->io[window].flags = 0;
+	sc->io[window].width = 0;
+}
+
+static int
+exca_io_findmap(struct exca_softc *sc, struct resource *res)
+{
+	int win;
+
+	for (win = 0; win < EXCA_IO_WINS; win++) {
+		if (sc->io[win].iot == rman_get_bustag(res) &&
+		    sc->io[win].addr == rman_get_start(res) &&
+		    sc->io[win].size == rman_get_size(res))
+			return (win);
+	}
+	return (-1);
+}
+
+
+int
+exca_io_unmap_res(struct exca_softc *sc, struct resource *res)
+{
+	int win;
+
+	win = exca_io_findmap(sc, res);
+	if (win < 0)
+		return (ENOENT);
+	exca_io_unmap(sc, win);
+	return (0);
+}
+
+/* Misc */
+
+/*
+ * If interrupts are enabled, then we should be able to just wait for
+ * an interrupt routine to wake us up.  Busy waiting shouldn't be
+ * necessary.  Sadly, not all legacy ISA cards support an interrupt
+ * for the busy state transitions, at least according to their datasheets, 
+ * so we busy wait a while here..
+ */
+static void
+exca_wait_ready(struct exca_softc *sc)
+{
+	int i;
+	DEVPRINTF(sc->dev, "exca_wait_ready: status 0x%02x\n",
+	    exca_read(sc, EXCA_IF_STATUS));
+	for (i = 0; i < 10000; i++) {
+		if (exca_read(sc, EXCA_IF_STATUS) & EXCA_IF_STATUS_READY)
+			return;
+		DELAY(500);
+	}
+	device_printf(sc->dev, "ready never happened, status = %02x\n",
+	    exca_read(sc, EXCA_IF_STATUS));
+}
+
+/*
+ * Reset the card.  Ideally, we'd do a lot of this via interrupts.
+ * However, many PC Cards will deassert the ready signal.  This means
+ * that they are asserting an interrupt.  This makes it hard to 
+ * do anything but a busy wait here.  One could argue that these
+ * such cards are broken, or that the bridge that allows this sort
+ * of interrupt through isn't quite what you'd want (and may be a standards
+ * violation).  However, such arguing would leave a huge class of pc cards
+ * and bridges out of reach for 
+ */
+void
+exca_reset(struct exca_softc *sc, device_t child)
+{
+	int cardtype;
+	int win;
+
+	/* enable socket i/o */
+	exca_setb(sc, EXCA_PWRCTL, EXCA_PWRCTL_OE);
+
+	exca_write(sc, EXCA_INTR, EXCA_INTR_ENABLE);
+	/* hold reset for 30ms */
+	DELAY(30*1000);
+	/* clear the reset flag */
+	exca_setb(sc, EXCA_INTR, EXCA_INTR_RESET);
+	/* wait 20ms as per pc card standard (r2.01) section 4.3.6 */
+	DELAY(20*1000);
+
+	exca_wait_ready(sc);
+
+	/* disable all address windows */
+	exca_write(sc, EXCA_ADDRWIN_ENABLE, 0);
+
+	CARD_GET_TYPE(child, &cardtype);
+	exca_setb(sc, EXCA_INTR, (cardtype == PCCARD_IFTYPE_IO) ?
+	    EXCA_INTR_CARDTYPE_IO : EXCA_INTR_CARDTYPE_MEM);
+	DEVPRINTF(sc->dev, "card type is %s\n",
+	    (cardtype == PCCARD_IFTYPE_IO) ? "io" : "mem");
+
+	/* reinstall all the memory and io mappings */
+	for (win = 0; win < EXCA_MEM_WINS; ++win)
+		if (sc->memalloc & (1 << win))
+			exca_do_mem_map(sc, win);
+	for (win = 0; win < EXCA_IO_WINS; ++win)
+		if (sc->ioalloc & (1 << win))
+			exca_do_io_map(sc, win);
+}
+
+/*
+ * Initialize the exca_softc data structure for the first time.
+ */
+void
+exca_init(struct exca_softc *sc, device_t dev, exca_write_t *wrfn,
+    exca_read_t *rdfn, bus_space_tag_t bst, bus_space_handle_t bsh,
+    uint32_t offset)
+{
+	sc->dev = dev;
+	sc->write_exca = wrfn;
+	sc->read_exca = rdfn;
+	sc->memalloc = 0;
+	sc->ioalloc = 0;
+	sc->bst = bst;
+	sc->bsh = bsh;
+	sc->offset = offset;
+	sc->flags = 0;
+}
+
+/*
+ * Probe the expected slots.  We maybe should set the ID for each of these
+ * slots too while we're at it.  But maybe that belongs to a separate
+ * function.
+ *
+ * Callers must charantee that there are at least EXCA_NSLOTS (4) in
+ * the array that they pass the address of the first element in the
+ * "exca" parameter.
+ */
+int
+exca_probe_slots(device_t dev, struct exca_softc *exca, exca_write_t writefnp,
+    exca_read_t readfnp)
+{
+	int rid;
+	struct resource *res;
+	int err;
+	bus_space_tag_t iot;
+	bus_space_handle_t ioh;
+	int i;
+
+	err = ENXIO;
+	rid = 0;
+	res = bus_alloc_resource(dev, SYS_RES_IOPORT, &rid, 0, ~0, EXCA_IOSIZE,
+	    RF_ACTIVE);
+	if (res == NULL)
+		return (ENXIO);
+	iot = rman_get_bustag(res);
+	ioh = rman_get_bushandle(res);
+	for (i = 0; i < EXCA_NSLOTS; i++) {
+		exca_init(&exca[i], dev, writefnp, readfnp, iot, ioh,
+		    i * EXCA_SOCKET_SIZE);
+		if (exca_is_pcic(&exca[i])) {
+			err = 0;
+			exca[i].flags |= EXCA_SOCKET_PRESENT;
+		}
+	}
+	bus_release_resource(dev, SYS_RES_IOPORT, rid, res);
+	return (err);
+}
+
+int
+exca_is_pcic(struct exca_softc *sc)
+{
+	/* XXX */
+	return (0);
+}