Fixed MTP to work with TWRP

drivers/nubus/nubus.c

@@ -0,0 +1,997 @@
+/*
+ *	Macintosh Nubus Interface Code
+ *
+ *      Originally by Alan Cox
+ *
+ *      Mostly rewritten by David Huggins-Daines, C. Scott Ananian,
+ *      and others.
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/nubus.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <asm/setup.h>
+#include <asm/page.h>
+#include <asm/hwtest.h>
+#include <asm/mac_via.h>
+#include <asm/mac_oss.h>
+
+extern void via_nubus_init(void);
+extern void oss_nubus_init(void);
+
+/* Constants */
+
+/* This is, of course, the size in bytelanes, rather than the size in
+   actual bytes */
+#define FORMAT_BLOCK_SIZE 20
+#define ROM_DIR_OFFSET 0x24
+
+#define NUBUS_TEST_PATTERN 0x5A932BC7
+
+/* Define this if you like to live dangerously - it is known not to
+   work on pretty much every machine except the Quadra 630 and the LC
+   III. */
+#undef I_WANT_TO_PROBE_SLOT_ZERO
+
+/* This sometimes helps combat failure to boot */
+#undef TRY_TO_DODGE_WSOD
+
+/* Globals */
+
+struct nubus_dev*   nubus_devices;
+struct nubus_board* nubus_boards;
+
+/* Meaning of "bytelanes":
+
+   The card ROM may appear on any or all bytes of each long word in
+   NuBus memory.  The low 4 bits of the "map" value found in the
+   format block (at the top of the slot address space, as well as at
+   the top of the MacOS ROM) tells us which bytelanes, i.e. which byte
+   offsets within each longword, are valid.  Thus:
+
+   A map of 0x0f, as found in the MacOS ROM, means that all bytelanes
+   are valid.
+
+   A map of 0xf0 means that no bytelanes are valid (We pray that we
+   will never encounter this, but stranger things have happened)
+
+   A map of 0xe1 means that only the MSB of each long word is actually
+   part of the card ROM.  (We hope to never encounter NuBus on a
+   little-endian machine.  Again, stranger things have happened)
+
+   A map of 0x78 means that only the LSB of each long word is valid.
+
+   Etcetera, etcetera.  Hopefully this clears up some confusion over
+   what the following code actually does.  */
+ 
+static inline int not_useful(void *p, int map)
+{
+	unsigned long pv=(unsigned long)p;
+	pv &= 3;
+	if(map & (1<<pv))
+		return 0;
+	return 1;
+}
+ 
+static unsigned long nubus_get_rom(unsigned char **ptr, int len, int map)
+{
+	/* This will hold the result */
+	unsigned long v = 0;
+	unsigned char *p = *ptr;
+
+	while(len)
+	{
+		v <<= 8;
+		while(not_useful(p,map))
+			p++;
+		v |= *p++;
+		len--;
+	}
+	*ptr = p;
+	return v;
+}
+
+static void nubus_rewind(unsigned char **ptr, int len, int map)
+{
+	unsigned char *p=*ptr;
+
+	/* Sanity check */
+	if(len > 65536)
+		printk(KERN_ERR "rewind of 0x%08x!\n", len);
+	while(len)
+	{
+		do
+		{
+			p--;
+		}
+		while(not_useful(p, map));
+		len--;
+	}
+	*ptr=p;
+}
+
+static void nubus_advance(unsigned char **ptr, int len, int map)
+{
+	unsigned char *p = *ptr;
+	if(len>65536)
+		printk(KERN_ERR "advance of 0x%08x!\n", len);
+	while(len)
+	{
+		while(not_useful(p,map))
+			p++;
+		p++;
+		len--;
+	}
+	*ptr = p;
+}
+
+static void nubus_move(unsigned char **ptr, int len, int map)
+{
+	if(len > 0)
+		nubus_advance(ptr, len, map);
+	else if(len < 0)
+		nubus_rewind(ptr, -len, map);
+}
+
+/* Now, functions to read the sResource tree */
+
+/* Each sResource entry consists of a 1-byte ID and a 3-byte data
+   field.  If that data field contains an offset, then obviously we
+   have to expand it from a 24-bit signed number to a 32-bit signed
+   number. */
+
+static inline long nubus_expand32(long foo)
+{
+	if(foo & 0x00800000)	/* 24bit negative */
+		foo |= 0xFF000000;
+	return foo;
+}
+
+static inline void *nubus_rom_addr(int slot)
+{	
+	/*
+	 *	Returns the first byte after the card. We then walk
+	 *	backwards to get the lane register and the config
+	 */
+	return (void *)(0xF1000000+(slot<<24));
+}
+
+static unsigned char *nubus_dirptr(const struct nubus_dirent *nd)
+{
+	unsigned char *p = nd->base;
+	/* Essentially, just step over the bytelanes using whatever
+	   offset we might have found */
+	nubus_move(&p, nubus_expand32(nd->data), nd->mask);
+	/* And return the value */
+	return p;
+}
+
+/* These two are for pulling resource data blocks (i.e. stuff that's
+   pointed to with offsets) out of the card ROM. */
+
+void nubus_get_rsrc_mem(void *dest, const struct nubus_dirent* dirent,
+			int len)
+{
+	unsigned char *t = (unsigned char *)dest;
+	unsigned char *p = nubus_dirptr(dirent);
+	while(len)
+	{
+		*t++ = nubus_get_rom(&p, 1, dirent->mask);
+		len--;
+	}
+}
+EXPORT_SYMBOL(nubus_get_rsrc_mem);
+
+void nubus_get_rsrc_str(void *dest, const struct nubus_dirent* dirent,
+			int len)
+{
+	unsigned char *t=(unsigned char *)dest;
+	unsigned char *p = nubus_dirptr(dirent);
+	while(len)
+	{
+		*t = nubus_get_rom(&p, 1, dirent->mask);
+		if(!*t++)
+			break;
+		len--;
+	}
+}
+EXPORT_SYMBOL(nubus_get_rsrc_str);
+
+int nubus_get_root_dir(const struct nubus_board* board,
+		       struct nubus_dir* dir)
+{
+	dir->ptr = dir->base = board->directory;
+	dir->done = 0;
+	dir->mask = board->lanes;
+	return 0;
+}
+EXPORT_SYMBOL(nubus_get_root_dir);
+
+/* This is a slyly renamed version of the above */
+int nubus_get_func_dir(const struct nubus_dev* dev,
+		       struct nubus_dir* dir)
+{
+	dir->ptr = dir->base = dev->directory;
+	dir->done = 0;
+	dir->mask = dev->board->lanes;
+	return 0;
+}
+EXPORT_SYMBOL(nubus_get_func_dir);
+
+int nubus_get_board_dir(const struct nubus_board* board,
+			struct nubus_dir* dir)
+{
+	struct nubus_dirent ent;
+	
+	dir->ptr = dir->base = board->directory;
+	dir->done = 0;
+	dir->mask = board->lanes;
+
+	/* Now dereference it (the first directory is always the board
+	   directory) */
+	if (nubus_readdir(dir, &ent) == -1)
+		return -1;
+	if (nubus_get_subdir(&ent, dir) == -1)
+		return -1;
+	return 0;
+}
+EXPORT_SYMBOL(nubus_get_board_dir);
+
+int nubus_get_subdir(const struct nubus_dirent *ent,
+		     struct nubus_dir *dir)
+{
+	dir->ptr = dir->base = nubus_dirptr(ent);
+	dir->done = 0;
+	dir->mask = ent->mask;
+	return 0;
+}
+EXPORT_SYMBOL(nubus_get_subdir);
+
+int nubus_readdir(struct nubus_dir *nd, struct nubus_dirent *ent)
+{
+	u32 resid;
+	if (nd->done)
+		return -1;
+
+	/* Do this first, otherwise nubus_rewind & co are off by 4 */
+	ent->base = nd->ptr;
+
+	/* This moves nd->ptr forward */
+	resid = nubus_get_rom(&nd->ptr, 4, nd->mask);
+
+	/* EOL marker, as per the Apple docs */
+	if((resid&0xff000000) == 0xff000000)
+	{
+		/* Mark it as done */
+		nd->done = 1;
+		return -1;
+	}
+
+	/* First byte is the resource ID */
+	ent->type  = resid >> 24;
+	/* Low 3 bytes might contain data (or might not) */
+	ent->data = resid & 0xffffff;
+	ent->mask  = nd->mask;
+	return 0;
+}
+EXPORT_SYMBOL(nubus_readdir);
+
+int nubus_rewinddir(struct nubus_dir* dir)
+{
+	dir->ptr = dir->base;
+	return 0;
+}
+EXPORT_SYMBOL(nubus_rewinddir);
+
+/* Driver interface functions, more or less like in pci.c */
+
+struct nubus_dev*
+nubus_find_device(unsigned short category,
+		  unsigned short type,
+		  unsigned short dr_hw,
+		  unsigned short dr_sw,
+		  const struct nubus_dev* from)
+{
+	struct nubus_dev* itor =
+		from ? from->next : nubus_devices;
+
+	while (itor) {
+		if (itor->category == category
+		    && itor->type == type
+		    && itor->dr_hw == dr_hw
+		    && itor->dr_sw == dr_sw)
+			return itor;
+		itor = itor->next;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(nubus_find_device);
+
+struct nubus_dev*
+nubus_find_type(unsigned short category,
+		unsigned short type,
+		const struct nubus_dev* from)
+{
+	struct nubus_dev* itor =
+		from ? from->next : nubus_devices;
+
+	while (itor) {
+		if (itor->category == category
+		    && itor->type == type)
+			return itor;
+		itor = itor->next;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(nubus_find_type);
+
+struct nubus_dev*
+nubus_find_slot(unsigned int slot,
+		const struct nubus_dev* from)
+{
+	struct nubus_dev* itor =
+		from ? from->next : nubus_devices;
+	
+	while (itor) {
+		if (itor->board->slot == slot)
+			return itor;
+		itor = itor->next;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(nubus_find_slot);
+
+int
+nubus_find_rsrc(struct nubus_dir* dir, unsigned char rsrc_type,
+		struct nubus_dirent* ent)
+{
+	while (nubus_readdir(dir, ent) != -1) {
+		if (ent->type == rsrc_type)
+			return 0;
+	}	
+	return -1;
+}
+EXPORT_SYMBOL(nubus_find_rsrc);
+
+/* Initialization functions - decide which slots contain stuff worth
+   looking at, and print out lots and lots of information from the
+   resource blocks. */
+
+/* FIXME: A lot of this stuff will eventually be useful after
+   initialization, for intelligently probing Ethernet and video chips,
+   among other things.  The rest of it should go in the /proc code.
+   For now, we just use it to give verbose boot logs. */
+
+static int __init nubus_show_display_resource(struct nubus_dev* dev,
+					      const struct nubus_dirent* ent)
+{
+	switch (ent->type) {
+	case NUBUS_RESID_GAMMADIR:
+		printk(KERN_INFO "    gamma directory offset: 0x%06x\n", ent->data);
+		break;
+	case 0x0080 ... 0x0085:
+		printk(KERN_INFO "    mode %02X info offset: 0x%06x\n",
+		       ent->type, ent->data);
+		break;
+	default:
+		printk(KERN_INFO "    unknown resource %02X, data 0x%06x\n",
+		       ent->type, ent->data);
+	}
+	return 0;
+}
+
+static int __init nubus_show_network_resource(struct nubus_dev* dev,
+					      const struct nubus_dirent* ent)
+{
+	switch (ent->type) {
+	case NUBUS_RESID_MAC_ADDRESS:
+	{
+		char addr[6];
+		int i;
+		
+		nubus_get_rsrc_mem(addr, ent, 6);
+		printk(KERN_INFO "    MAC address: ");
+		for (i = 0; i < 6; i++)
+			printk("%02x%s", addr[i] & 0xff,
+			       i == 5 ? "" : ":");
+		printk("\n");
+		break;
+	}
+	default:
+		printk(KERN_INFO "    unknown resource %02X, data 0x%06x\n",
+		       ent->type, ent->data);
+	}
+	return 0;
+}
+
+static int __init nubus_show_cpu_resource(struct nubus_dev* dev,
+					  const struct nubus_dirent* ent)
+{
+	switch (ent->type) {
+	case NUBUS_RESID_MEMINFO:
+	{
+		unsigned long meminfo[2];
+		nubus_get_rsrc_mem(&meminfo, ent, 8);
+		printk(KERN_INFO "    memory: [ 0x%08lx 0x%08lx ]\n",
+		       meminfo[0], meminfo[1]);
+		break;
+	}
+	case NUBUS_RESID_ROMINFO:
+	{
+		unsigned long rominfo[2];
+		nubus_get_rsrc_mem(&rominfo, ent, 8);
+		printk(KERN_INFO "    ROM:    [ 0x%08lx 0x%08lx ]\n",
+		       rominfo[0], rominfo[1]);
+		break;
+	}
+	default:
+		printk(KERN_INFO "    unknown resource %02X, data 0x%06x\n",
+		       ent->type, ent->data);
+	}
+	return 0;
+}
+
+static int __init nubus_show_private_resource(struct nubus_dev* dev,
+					      const struct nubus_dirent* ent)
+{
+	switch (dev->category) {
+	case NUBUS_CAT_DISPLAY:
+		nubus_show_display_resource(dev, ent);
+		break;
+	case NUBUS_CAT_NETWORK:
+		nubus_show_network_resource(dev, ent);
+		break;
+	case NUBUS_CAT_CPU:
+		nubus_show_cpu_resource(dev, ent);
+		break;
+	default:
+		printk(KERN_INFO "    unknown resource %02X, data 0x%06x\n",
+		       ent->type, ent->data);
+	}
+	return 0;
+}
+
+static struct nubus_dev* __init
+	   nubus_get_functional_resource(struct nubus_board* board,
+					 int slot,
+					 const struct nubus_dirent* parent)
+{
+	struct nubus_dir    dir;
+	struct nubus_dirent ent;
+	struct nubus_dev*   dev;
+	
+	printk(KERN_INFO "  Function 0x%02x:\n", parent->type);
+	nubus_get_subdir(parent, &dir);
+
+	/* Apple seems to have botched the ROM on the IIx */
+	if (slot == 0 && (unsigned long)dir.base % 2)
+		dir.base += 1;
+	
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+		printk(KERN_DEBUG "nubus_get_functional_resource: parent is 0x%p, dir is 0x%p\n",
+		       parent->base, dir.base);
+
+	/* Actually we should probably panic if this fails */
+	if ((dev = kzalloc(sizeof(*dev), GFP_ATOMIC)) == NULL)
+		return NULL;	
+	dev->resid = parent->type;
+	dev->directory = dir.base;
+	dev->board = board;
+	
+	while (nubus_readdir(&dir, &ent) != -1)
+	{
+		switch(ent.type)
+		{
+		case NUBUS_RESID_TYPE:
+		{
+			unsigned short nbtdata[4];
+			nubus_get_rsrc_mem(nbtdata, &ent, 8);
+			dev->category = nbtdata[0];
+			dev->type     = nbtdata[1];
+			dev->dr_sw    = nbtdata[2];
+			dev->dr_hw    = nbtdata[3];
+			printk(KERN_INFO "    type: [cat 0x%x type 0x%x hw 0x%x sw 0x%x]\n",
+			       nbtdata[0], nbtdata[1], nbtdata[2], nbtdata[3]);
+			break;
+		}
+		case NUBUS_RESID_NAME:
+		{
+			nubus_get_rsrc_str(dev->name, &ent, 64);
+			printk(KERN_INFO "    name: %s\n", dev->name);
+			break;
+		}
+		case NUBUS_RESID_DRVRDIR:
+		{
+			/* MacOS driver.  If we were NetBSD we might
+			   use this :-) */
+			struct nubus_dir drvr_dir;
+			struct nubus_dirent drvr_ent;
+			nubus_get_subdir(&ent, &drvr_dir);
+			nubus_readdir(&drvr_dir, &drvr_ent);
+			dev->driver = nubus_dirptr(&drvr_ent);
+			printk(KERN_INFO "    driver at: 0x%p\n",
+			       dev->driver);
+			break;
+		}
+		case NUBUS_RESID_MINOR_BASEOS:
+			/* We will need this in order to support
+			   multiple framebuffers.  It might be handy
+			   for Ethernet as well */
+			nubus_get_rsrc_mem(&dev->iobase, &ent, 4);
+			printk(KERN_INFO "    memory offset: 0x%08lx\n",
+			       dev->iobase);
+			break;
+		case NUBUS_RESID_MINOR_LENGTH:
+			/* Ditto */
+			nubus_get_rsrc_mem(&dev->iosize, &ent, 4);
+			printk(KERN_INFO "    memory length: 0x%08lx\n",
+			       dev->iosize);
+			break;			
+		case NUBUS_RESID_FLAGS:
+			dev->flags = ent.data;
+			printk(KERN_INFO "    flags: 0x%06x\n", dev->flags);
+			break;
+		case NUBUS_RESID_HWDEVID:
+			dev->hwdevid = ent.data;
+			printk(KERN_INFO "    hwdevid: 0x%06x\n", dev->hwdevid);
+			break;
+		default:
+			/* Local/Private resources have their own
+			   function */
+			nubus_show_private_resource(dev, &ent);
+		}
+	}
+		
+	return dev;
+}
+
+/* This is cool. */
+static int __init nubus_get_vidnames(struct nubus_board* board,
+				     const struct nubus_dirent* parent)
+{
+	struct nubus_dir    dir;
+	struct nubus_dirent ent;
+	/* FIXME: obviously we want to put this in a header file soon */
+	struct vidmode {
+		u32 size;
+		/* Don't know what this is yet */
+		u16 id;
+		/* Longest one I've seen so far is 26 characters */
+		char name[32];
+	};
+
+	printk(KERN_INFO "    video modes supported:\n");
+	nubus_get_subdir(parent, &dir);
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+		printk(KERN_DEBUG "nubus_get_vidnames: parent is 0x%p, dir is 0x%p\n",
+		       parent->base, dir.base);
+
+	while(nubus_readdir(&dir, &ent) != -1)
+	{
+		struct vidmode mode;
+		u32 size;
+
+		/* First get the length */
+		nubus_get_rsrc_mem(&size, &ent, 4);
+		
+		/* Now clobber the whole thing */
+		if (size > sizeof(mode) - 1)
+			size = sizeof(mode) - 1;
+		memset(&mode, 0, sizeof(mode));
+		nubus_get_rsrc_mem(&mode, &ent, size);
+		printk (KERN_INFO "      %02X: (%02X) %s\n", ent.type,
+			mode.id, mode.name);
+	}
+	return 0;
+}
+
+/* This is *really* cool. */
+static int __init nubus_get_icon(struct nubus_board* board,
+				 const struct nubus_dirent* ent)
+{
+	/* Should be 32x32 if my memory serves me correctly */
+	unsigned char icon[128];
+	int x, y;
+	
+	nubus_get_rsrc_mem(&icon, ent, 128);
+	printk(KERN_INFO "    icon:\n");
+
+	/* We should actually plot these somewhere in the framebuffer
+	   init.  This is just to demonstrate that they do, in fact,
+	   exist */
+	for (y = 0; y < 32; y++) {
+		printk(KERN_INFO "      ");
+		for (x = 0; x < 32; x++) {
+			if (icon[y*4 + x/8]
+			    & (0x80 >> (x%8)))
+				printk("*");
+			else
+				printk(" ");
+		}
+		printk("\n");
+	}
+	return 0;
+}
+
+static int __init nubus_get_vendorinfo(struct nubus_board* board,
+				       const struct nubus_dirent* parent)
+{
+	struct nubus_dir    dir;
+	struct nubus_dirent ent;
+	static char* vendor_fields[6] = {"ID", "serial", "revision",
+					 "part", "date", "unknown field"};
+
+	printk(KERN_INFO "    vendor info:\n");
+	nubus_get_subdir(parent, &dir);
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+		printk(KERN_DEBUG "nubus_get_vendorinfo: parent is 0x%p, dir is 0x%p\n",
+		       parent->base, dir.base);
+
+	while(nubus_readdir(&dir, &ent) != -1)
+	{
+		char name[64];
+		
+		/* These are all strings, we think */
+		nubus_get_rsrc_str(name, &ent, 64);
+		if (ent.type > 5)
+			ent.type = 5;
+		printk(KERN_INFO "    %s: %s\n",
+		       vendor_fields[ent.type-1], name);
+	}
+	return 0;
+}
+
+static int __init nubus_get_board_resource(struct nubus_board* board, int slot,
+					   const struct nubus_dirent* parent)
+{
+	struct nubus_dir    dir;
+	struct nubus_dirent ent;
+	
+	nubus_get_subdir(parent, &dir);
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+		printk(KERN_DEBUG "nubus_get_board_resource: parent is 0x%p, dir is 0x%p\n",
+		       parent->base, dir.base);
+
+	while(nubus_readdir(&dir, &ent) != -1)
+	{
+		switch (ent.type) {
+		case NUBUS_RESID_TYPE:
+		{
+			unsigned short nbtdata[4];
+			/* This type is always the same, and is not
+			   useful except insofar as it tells us that
+			   we really are looking at a board resource. */
+			nubus_get_rsrc_mem(nbtdata, &ent, 8);
+			printk(KERN_INFO "    type: [cat 0x%x type 0x%x hw 0x%x sw 0x%x]\n",
+			       nbtdata[0], nbtdata[1], nbtdata[2],
+			       nbtdata[3]);
+			if (nbtdata[0] != 1 || nbtdata[1] != 0 ||
+			    nbtdata[2] != 0 || nbtdata[3] != 0)
+				printk(KERN_ERR "this sResource is not a board resource!\n");
+			break;
+		}
+		case NUBUS_RESID_NAME:
+			nubus_get_rsrc_str(board->name, &ent, 64);
+			printk(KERN_INFO "    name: %s\n", board->name);
+			break;
+		case NUBUS_RESID_ICON:
+			nubus_get_icon(board, &ent);
+			break;
+		case NUBUS_RESID_BOARDID:
+			printk(KERN_INFO "    board id: 0x%x\n", ent.data);
+			break;
+		case NUBUS_RESID_PRIMARYINIT:
+			printk(KERN_INFO "    primary init offset: 0x%06x\n", ent.data);
+			break;
+		case NUBUS_RESID_VENDORINFO:
+			nubus_get_vendorinfo(board, &ent);
+			break;
+		case NUBUS_RESID_FLAGS:
+			printk(KERN_INFO "    flags: 0x%06x\n", ent.data);
+			break;
+		case NUBUS_RESID_HWDEVID:
+			printk(KERN_INFO "    hwdevid: 0x%06x\n", ent.data);
+			break;
+		case NUBUS_RESID_SECONDINIT:
+			printk(KERN_INFO "    secondary init offset: 0x%06x\n", ent.data);
+			break;
+			/* WTF isn't this in the functional resources? */ 
+		case NUBUS_RESID_VIDNAMES:
+			nubus_get_vidnames(board, &ent);
+			break;
+			/* Same goes for this */
+		case NUBUS_RESID_VIDMODES:
+			printk(KERN_INFO "    video mode parameter directory offset: 0x%06x\n",
+			       ent.data);
+			break;			
+		default:
+			printk(KERN_INFO "    unknown resource %02X, data 0x%06x\n",
+			       ent.type, ent.data);
+		}
+	}
+	return 0;
+}
+
+/* Attempt to bypass the somewhat non-obvious arrangement of
+   sResources in the motherboard ROM */
+static void __init nubus_find_rom_dir(struct nubus_board* board)
+{
+	unsigned char* rp;
+	unsigned char* romdir;
+	struct nubus_dir dir;
+	struct nubus_dirent ent;
+
+	/* Check for the extra directory just under the format block */
+	rp = board->fblock;
+	nubus_rewind(&rp, 4, board->lanes);
+	if (nubus_get_rom(&rp, 4, board->lanes) != NUBUS_TEST_PATTERN) {
+		/* OK, the ROM was telling the truth */
+		board->directory = board->fblock;
+		nubus_move(&board->directory,
+			   nubus_expand32(board->doffset),
+			   board->lanes);
+		return;
+	}
+
+	/* On "slot zero", you have to walk down a few more
+	   directories to get to the equivalent of a real card's root
+	   directory.  We don't know what they were smoking when they
+	   came up with this. */
+	romdir = nubus_rom_addr(board->slot);
+	nubus_rewind(&romdir, ROM_DIR_OFFSET, board->lanes);
+	dir.base = dir.ptr = romdir;
+	dir.done = 0;
+	dir.mask = board->lanes;
+
+	/* This one points to an "Unknown Macintosh" directory */
+	if (nubus_readdir(&dir, &ent) == -1)
+		goto badrom;
+
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+		printk(KERN_INFO "nubus_get_rom_dir: entry %02x %06x\n", ent.type, ent.data);
+	/* This one takes us to where we want to go. */
+	if (nubus_readdir(&dir, &ent) == -1) 
+		goto badrom;
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+		printk(KERN_DEBUG "nubus_get_rom_dir: entry %02x %06x\n", ent.type, ent.data);
+	nubus_get_subdir(&ent, &dir);
+
+	/* Resource ID 01, also an "Unknown Macintosh" */
+	if (nubus_readdir(&dir, &ent) == -1) 
+		goto badrom;
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+		printk(KERN_DEBUG "nubus_get_rom_dir: entry %02x %06x\n", ent.type, ent.data);
+
+	/* FIXME: the first one is *not* always the right one.  We
+	   suspect this has something to do with the ROM revision.
+	   "The HORROR ROM" (LC-series) uses 0x7e, while "The HORROR
+	   Continues" (Q630) uses 0x7b.  The DAFB Macs evidently use
+	   something else.  Please run "Slots" on your Mac (see
+	   include/linux/nubus.h for where to get this program) and
+	   tell us where the 'SiDirPtr' for Slot 0 is.  If you feel
+	   brave, you should also use MacsBug to walk down the ROM
+	   directories like this function does and try to find the
+	   path to that address... */
+	if (nubus_readdir(&dir, &ent) == -1)
+		goto badrom;
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+		printk(KERN_DEBUG "nubus_get_rom_dir: entry %02x %06x\n", ent.type, ent.data);
+	
+	/* Bwahahahaha... */
+	nubus_get_subdir(&ent, &dir);
+	board->directory = dir.base;
+	return;
+	
+	/* Even more evil laughter... */
+ badrom:
+	board->directory = board->fblock;
+	nubus_move(&board->directory, nubus_expand32(board->doffset), board->lanes);
+	printk(KERN_ERR "nubus_get_rom_dir: ROM weirdness!  Notify the developers...\n");
+}
+
+/* Add a board (might be many devices) to the list */
+static struct nubus_board* __init nubus_add_board(int slot, int bytelanes)
+{
+	struct nubus_board* board;
+	struct nubus_board** boardp;
+
+	unsigned char *rp;
+	unsigned long dpat;
+	struct nubus_dir dir;
+	struct nubus_dirent ent;
+
+	/* Move to the start of the format block */
+	rp = nubus_rom_addr(slot);		
+	nubus_rewind(&rp, FORMAT_BLOCK_SIZE, bytelanes);
+
+	/* Actually we should probably panic if this fails */
+	if ((board = kzalloc(sizeof(*board), GFP_ATOMIC)) == NULL)
+		return NULL;	
+	board->fblock = rp;
+
+	/* Dump the format block for debugging purposes */
+	if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG) {
+		int i;
+		printk(KERN_DEBUG "Slot %X, format block at 0x%p\n",
+		       slot, rp);
+		printk(KERN_DEBUG "Format block: ");
+		for (i = 0; i < FORMAT_BLOCK_SIZE; i += 4) {
+			unsigned short foo, bar;
+			foo = nubus_get_rom(&rp, 2, bytelanes);
+			bar = nubus_get_rom(&rp, 2, bytelanes);
+			printk("%04x %04x  ", foo, bar);
+		}
+		printk("\n");
+		rp = board->fblock;
+	}
+	
+	board->slot = slot;
+	board->slot_addr = (unsigned long) nubus_slot_addr(slot);
+	board->doffset = nubus_get_rom(&rp, 4, bytelanes);
+	/* rom_length is *supposed* to be the total length of the
+	 * ROM.  In practice it is the "amount of ROM used to compute
+	 * the CRC."  So some jokers decide to set it to zero and
+	 * set the crc to zero so they don't have to do any math.
+	 * See the Performa 460 ROM, for example.  Those Apple "engineers".
+	 */
+	board->rom_length = nubus_get_rom(&rp, 4, bytelanes);
+	board->crc = nubus_get_rom(&rp, 4, bytelanes);
+	board->rev = nubus_get_rom(&rp, 1, bytelanes);
+	board->format = nubus_get_rom(&rp,1, bytelanes);
+	board->lanes = bytelanes;
+
+	/* Directory offset should be small and negative... */
+	if(!(board->doffset & 0x00FF0000))
+		printk(KERN_WARNING "Dodgy doffset!\n");
+	dpat = nubus_get_rom(&rp, 4, bytelanes);
+	if(dpat != NUBUS_TEST_PATTERN)
+		printk(KERN_WARNING "Wrong test pattern %08lx!\n", dpat);
+		
+	/*
+	 *	I wonder how the CRC is meant to work -
+	 *		any takers ?
+	 * CSA: According to MAC docs, not all cards pass the CRC anyway,
+	 * since the initial Macintosh ROM releases skipped the check.
+	 */
+
+	/* Attempt to work around slot zero weirdness */
+	nubus_find_rom_dir(board);
+	nubus_get_root_dir(board, &dir);	
+
+	/* We're ready to rock */
+	printk(KERN_INFO "Slot %X:\n", slot);
+
+	/* Each slot should have one board resource and any number of
+	   functional resources.  So we'll fill in some fields in the
+	   struct nubus_board from the board resource, then walk down
+	   the list of functional resources, spinning out a nubus_dev
+	   for each of them. */
+	if (nubus_readdir(&dir, &ent) == -1) {
+		/* We can't have this! */
+		printk(KERN_ERR "Board resource not found!\n");
+		return NULL;
+	} else {
+		printk(KERN_INFO "  Board resource:\n");
+		nubus_get_board_resource(board, slot, &ent);
+	}
+
+	/* Aaaarrrrgghh!  The LC III motherboard has *two* board
+	   resources.  I have no idea WTF to do about this. */
+
+	while (nubus_readdir(&dir, &ent) != -1) {
+		struct nubus_dev*  dev;
+		struct nubus_dev** devp;
+		dev = nubus_get_functional_resource(board, slot, &ent);
+		if (dev == NULL)
+			continue;
+
+		/* We zeroed this out above */
+		if (board->first_dev == NULL)
+			board->first_dev = dev;
+		
+		/* Put it on the global NuBus device chain. Keep entries in order. */
+		for (devp=&nubus_devices; *devp!=NULL; devp=&((*devp)->next))
+			/* spin */;
+		*devp = dev;
+		dev->next = NULL;		
+	}
+
+	/* Put it on the global NuBus board chain. Keep entries in order. */
+	for (boardp=&nubus_boards; *boardp!=NULL; boardp=&((*boardp)->next))
+		/* spin */;
+	*boardp = board;
+	board->next = NULL;
+	
+	return board;
+}
+
+void __init nubus_probe_slot(int slot)
+{
+	unsigned char dp;
+	unsigned char* rp;
+	int i;
+
+	rp = nubus_rom_addr(slot);	
+	for(i = 4; i; i--)
+	{
+		unsigned long flags;
+		int card_present;
+
+		rp--;
+		local_irq_save(flags);
+		card_present = hwreg_present(rp);
+		local_irq_restore(flags);
+	       
+		if (!card_present)
+			continue;
+
+		printk(KERN_DEBUG "Now probing slot %X at %p\n", slot, rp);
+		dp = *rp;
+		if(dp == 0)
+			continue;
+
+		/* The last byte of the format block consists of two
+		   nybbles which are "mirror images" of each other.
+		   These show us the valid bytelanes */
+		if ((((dp>>4) ^ dp) & 0x0F) != 0x0F)
+			continue;
+		/* Check that this value is actually *on* one of the
+		   bytelanes it claims are valid! */
+		if ((dp & 0x0F) >= (1<<i))
+			continue;
+
+		/* Looks promising.  Let's put it on the list. */
+		nubus_add_board(slot, dp);
+
+		return;
+	}
+}
+
+void __init nubus_scan_bus(void)
+{
+	int slot;
+	/* This might not work on your machine */
+#ifdef I_WANT_TO_PROBE_SLOT_ZERO
+	nubus_probe_slot(0);
+#endif
+	for(slot = 9; slot < 15; slot++)
+	{
+		nubus_probe_slot(slot);
+	}
+}
+
+static int __init nubus_init(void)
+{
+	if (!MACH_IS_MAC) 
+		return 0;
+
+	/* Initialize the NuBus interrupts */
+	if (oss_present) {
+		oss_nubus_init();
+	} else {
+		via_nubus_init();
+	}
+
+#ifdef TRY_TO_DODGE_WSOD
+	/* Rogue Ethernet interrupts can kill the machine if we don't
+	   do this.  Obviously this is bogus.  Hopefully the local VIA
+	   gurus can fix the real cause of the problem. */
+	mdelay(1000);
+#endif
+	
+	/* And probe */
+	printk("NuBus: Scanning NuBus slots.\n");
+	nubus_devices = NULL;
+	nubus_boards  = NULL;
+	nubus_scan_bus();
+	nubus_proc_init();
+	return 0;
+}
+
+subsys_initcall(nubus_init);