xref: /linux/arch/arm/kernel/bios32.c (revision 04eeb606a8383b306f4bc6991da8231b5f3924b0)
1 /*
2  *  linux/arch/arm/kernel/bios32.c
3  *
4  *  PCI bios-type initialisation for PCI machines
5  *
6  *  Bits taken from various places.
7  */
8 #include <linux/export.h>
9 #include <linux/kernel.h>
10 #include <linux/pci.h>
11 #include <linux/slab.h>
12 #include <linux/init.h>
13 #include <linux/io.h>
14 
15 #include <asm/mach-types.h>
16 #include <asm/mach/map.h>
17 #include <asm/mach/pci.h>
18 
19 static int debug_pci;
20 
21 /*
22  * We can't use pci_get_device() here since we are
23  * called from interrupt context.
24  */
25 static void pcibios_bus_report_status(struct pci_bus *bus, u_int status_mask, int warn)
26 {
27 	struct pci_dev *dev;
28 
29 	list_for_each_entry(dev, &bus->devices, bus_list) {
30 		u16 status;
31 
32 		/*
33 		 * ignore host bridge - we handle
34 		 * that separately
35 		 */
36 		if (dev->bus->number == 0 && dev->devfn == 0)
37 			continue;
38 
39 		pci_read_config_word(dev, PCI_STATUS, &status);
40 		if (status == 0xffff)
41 			continue;
42 
43 		if ((status & status_mask) == 0)
44 			continue;
45 
46 		/* clear the status errors */
47 		pci_write_config_word(dev, PCI_STATUS, status & status_mask);
48 
49 		if (warn)
50 			printk("(%s: %04X) ", pci_name(dev), status);
51 	}
52 
53 	list_for_each_entry(dev, &bus->devices, bus_list)
54 		if (dev->subordinate)
55 			pcibios_bus_report_status(dev->subordinate, status_mask, warn);
56 }
57 
58 void pcibios_report_status(u_int status_mask, int warn)
59 {
60 	struct pci_bus *bus;
61 
62 	list_for_each_entry(bus, &pci_root_buses, node)
63 		pcibios_bus_report_status(bus, status_mask, warn);
64 }
65 
66 /*
67  * We don't use this to fix the device, but initialisation of it.
68  * It's not the correct use for this, but it works.
69  * Note that the arbiter/ISA bridge appears to be buggy, specifically in
70  * the following area:
71  * 1. park on CPU
72  * 2. ISA bridge ping-pong
73  * 3. ISA bridge master handling of target RETRY
74  *
75  * Bug 3 is responsible for the sound DMA grinding to a halt.  We now
76  * live with bug 2.
77  */
78 static void pci_fixup_83c553(struct pci_dev *dev)
79 {
80 	/*
81 	 * Set memory region to start at address 0, and enable IO
82 	 */
83 	pci_write_config_dword(dev, PCI_BASE_ADDRESS_0, PCI_BASE_ADDRESS_SPACE_MEMORY);
84 	pci_write_config_word(dev, PCI_COMMAND, PCI_COMMAND_IO);
85 
86 	dev->resource[0].end -= dev->resource[0].start;
87 	dev->resource[0].start = 0;
88 
89 	/*
90 	 * All memory requests from ISA to be channelled to PCI
91 	 */
92 	pci_write_config_byte(dev, 0x48, 0xff);
93 
94 	/*
95 	 * Enable ping-pong on bus master to ISA bridge transactions.
96 	 * This improves the sound DMA substantially.  The fixed
97 	 * priority arbiter also helps (see below).
98 	 */
99 	pci_write_config_byte(dev, 0x42, 0x01);
100 
101 	/*
102 	 * Enable PCI retry
103 	 */
104 	pci_write_config_byte(dev, 0x40, 0x22);
105 
106 	/*
107 	 * We used to set the arbiter to "park on last master" (bit
108 	 * 1 set), but unfortunately the CyberPro does not park the
109 	 * bus.  We must therefore park on CPU.  Unfortunately, this
110 	 * may trigger yet another bug in the 553.
111 	 */
112 	pci_write_config_byte(dev, 0x83, 0x02);
113 
114 	/*
115 	 * Make the ISA DMA request lowest priority, and disable
116 	 * rotating priorities completely.
117 	 */
118 	pci_write_config_byte(dev, 0x80, 0x11);
119 	pci_write_config_byte(dev, 0x81, 0x00);
120 
121 	/*
122 	 * Route INTA input to IRQ 11, and set IRQ11 to be level
123 	 * sensitive.
124 	 */
125 	pci_write_config_word(dev, 0x44, 0xb000);
126 	outb(0x08, 0x4d1);
127 }
128 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_WINBOND, PCI_DEVICE_ID_WINBOND_83C553, pci_fixup_83c553);
129 
130 static void pci_fixup_unassign(struct pci_dev *dev)
131 {
132 	dev->resource[0].end -= dev->resource[0].start;
133 	dev->resource[0].start = 0;
134 }
135 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_WINBOND2, PCI_DEVICE_ID_WINBOND2_89C940F, pci_fixup_unassign);
136 
137 /*
138  * Prevent the PCI layer from seeing the resources allocated to this device
139  * if it is the host bridge by marking it as such.  These resources are of
140  * no consequence to the PCI layer (they are handled elsewhere).
141  */
142 static void pci_fixup_dec21285(struct pci_dev *dev)
143 {
144 	int i;
145 
146 	if (dev->devfn == 0) {
147 		dev->class &= 0xff;
148 		dev->class |= PCI_CLASS_BRIDGE_HOST << 8;
149 		for (i = 0; i < PCI_NUM_RESOURCES; i++) {
150 			dev->resource[i].start = 0;
151 			dev->resource[i].end   = 0;
152 			dev->resource[i].flags = 0;
153 		}
154 	}
155 }
156 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_DEC, PCI_DEVICE_ID_DEC_21285, pci_fixup_dec21285);
157 
158 /*
159  * PCI IDE controllers use non-standard I/O port decoding, respect it.
160  */
161 static void pci_fixup_ide_bases(struct pci_dev *dev)
162 {
163 	struct resource *r;
164 	int i;
165 
166 	if ((dev->class >> 8) != PCI_CLASS_STORAGE_IDE)
167 		return;
168 
169 	for (i = 0; i < PCI_NUM_RESOURCES; i++) {
170 		r = dev->resource + i;
171 		if ((r->start & ~0x80) == 0x374) {
172 			r->start |= 2;
173 			r->end = r->start;
174 		}
175 	}
176 }
177 DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, pci_fixup_ide_bases);
178 
179 /*
180  * Put the DEC21142 to sleep
181  */
182 static void pci_fixup_dec21142(struct pci_dev *dev)
183 {
184 	pci_write_config_dword(dev, 0x40, 0x80000000);
185 }
186 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_DEC, PCI_DEVICE_ID_DEC_21142, pci_fixup_dec21142);
187 
188 /*
189  * The CY82C693 needs some rather major fixups to ensure that it does
190  * the right thing.  Idea from the Alpha people, with a few additions.
191  *
192  * We ensure that the IDE base registers are set to 1f0/3f4 for the
193  * primary bus, and 170/374 for the secondary bus.  Also, hide them
194  * from the PCI subsystem view as well so we won't try to perform
195  * our own auto-configuration on them.
196  *
197  * In addition, we ensure that the PCI IDE interrupts are routed to
198  * IRQ 14 and IRQ 15 respectively.
199  *
200  * The above gets us to a point where the IDE on this device is
201  * functional.  However, The CY82C693U _does not work_ in bus
202  * master mode without locking the PCI bus solid.
203  */
204 static void pci_fixup_cy82c693(struct pci_dev *dev)
205 {
206 	if ((dev->class >> 8) == PCI_CLASS_STORAGE_IDE) {
207 		u32 base0, base1;
208 
209 		if (dev->class & 0x80) {	/* primary */
210 			base0 = 0x1f0;
211 			base1 = 0x3f4;
212 		} else {			/* secondary */
213 			base0 = 0x170;
214 			base1 = 0x374;
215 		}
216 
217 		pci_write_config_dword(dev, PCI_BASE_ADDRESS_0,
218 				       base0 | PCI_BASE_ADDRESS_SPACE_IO);
219 		pci_write_config_dword(dev, PCI_BASE_ADDRESS_1,
220 				       base1 | PCI_BASE_ADDRESS_SPACE_IO);
221 
222 		dev->resource[0].start = 0;
223 		dev->resource[0].end   = 0;
224 		dev->resource[0].flags = 0;
225 
226 		dev->resource[1].start = 0;
227 		dev->resource[1].end   = 0;
228 		dev->resource[1].flags = 0;
229 	} else if (PCI_FUNC(dev->devfn) == 0) {
230 		/*
231 		 * Setup IDE IRQ routing.
232 		 */
233 		pci_write_config_byte(dev, 0x4b, 14);
234 		pci_write_config_byte(dev, 0x4c, 15);
235 
236 		/*
237 		 * Disable FREQACK handshake, enable USB.
238 		 */
239 		pci_write_config_byte(dev, 0x4d, 0x41);
240 
241 		/*
242 		 * Enable PCI retry, and PCI post-write buffer.
243 		 */
244 		pci_write_config_byte(dev, 0x44, 0x17);
245 
246 		/*
247 		 * Enable ISA master and DMA post write buffering.
248 		 */
249 		pci_write_config_byte(dev, 0x45, 0x03);
250 	}
251 }
252 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_CONTAQ, PCI_DEVICE_ID_CONTAQ_82C693, pci_fixup_cy82c693);
253 
254 static void pci_fixup_it8152(struct pci_dev *dev)
255 {
256 	int i;
257 	/* fixup for ITE 8152 devices */
258 	/* FIXME: add defines for class 0x68000 and 0x80103 */
259 	if ((dev->class >> 8) == PCI_CLASS_BRIDGE_HOST ||
260 	    dev->class == 0x68000 ||
261 	    dev->class == 0x80103) {
262 		for (i = 0; i < PCI_NUM_RESOURCES; i++) {
263 			dev->resource[i].start = 0;
264 			dev->resource[i].end   = 0;
265 			dev->resource[i].flags = 0;
266 		}
267 	}
268 }
269 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ITE, PCI_DEVICE_ID_ITE_8152, pci_fixup_it8152);
270 
271 /*
272  * If the bus contains any of these devices, then we must not turn on
273  * parity checking of any kind.  Currently this is CyberPro 20x0 only.
274  */
275 static inline int pdev_bad_for_parity(struct pci_dev *dev)
276 {
277 	return ((dev->vendor == PCI_VENDOR_ID_INTERG &&
278 		 (dev->device == PCI_DEVICE_ID_INTERG_2000 ||
279 		  dev->device == PCI_DEVICE_ID_INTERG_2010)) ||
280 		(dev->vendor == PCI_VENDOR_ID_ITE &&
281 		 dev->device == PCI_DEVICE_ID_ITE_8152));
282 
283 }
284 
285 /*
286  * pcibios_fixup_bus - Called after each bus is probed,
287  * but before its children are examined.
288  */
289 void pcibios_fixup_bus(struct pci_bus *bus)
290 {
291 	struct pci_dev *dev;
292 	u16 features = PCI_COMMAND_SERR | PCI_COMMAND_PARITY | PCI_COMMAND_FAST_BACK;
293 
294 	/*
295 	 * Walk the devices on this bus, working out what we can
296 	 * and can't support.
297 	 */
298 	list_for_each_entry(dev, &bus->devices, bus_list) {
299 		u16 status;
300 
301 		pci_read_config_word(dev, PCI_STATUS, &status);
302 
303 		/*
304 		 * If any device on this bus does not support fast back
305 		 * to back transfers, then the bus as a whole is not able
306 		 * to support them.  Having fast back to back transfers
307 		 * on saves us one PCI cycle per transaction.
308 		 */
309 		if (!(status & PCI_STATUS_FAST_BACK))
310 			features &= ~PCI_COMMAND_FAST_BACK;
311 
312 		if (pdev_bad_for_parity(dev))
313 			features &= ~(PCI_COMMAND_SERR | PCI_COMMAND_PARITY);
314 
315 		switch (dev->class >> 8) {
316 		case PCI_CLASS_BRIDGE_PCI:
317 			pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &status);
318 			status |= PCI_BRIDGE_CTL_PARITY|PCI_BRIDGE_CTL_MASTER_ABORT;
319 			status &= ~(PCI_BRIDGE_CTL_BUS_RESET|PCI_BRIDGE_CTL_FAST_BACK);
320 			pci_write_config_word(dev, PCI_BRIDGE_CONTROL, status);
321 			break;
322 
323 		case PCI_CLASS_BRIDGE_CARDBUS:
324 			pci_read_config_word(dev, PCI_CB_BRIDGE_CONTROL, &status);
325 			status |= PCI_CB_BRIDGE_CTL_PARITY|PCI_CB_BRIDGE_CTL_MASTER_ABORT;
326 			pci_write_config_word(dev, PCI_CB_BRIDGE_CONTROL, status);
327 			break;
328 		}
329 	}
330 
331 	/*
332 	 * Now walk the devices again, this time setting them up.
333 	 */
334 	list_for_each_entry(dev, &bus->devices, bus_list) {
335 		u16 cmd;
336 
337 		pci_read_config_word(dev, PCI_COMMAND, &cmd);
338 		cmd |= features;
339 		pci_write_config_word(dev, PCI_COMMAND, cmd);
340 
341 		pci_write_config_byte(dev, PCI_CACHE_LINE_SIZE,
342 				      L1_CACHE_BYTES >> 2);
343 	}
344 
345 	/*
346 	 * Propagate the flags to the PCI bridge.
347 	 */
348 	if (bus->self && bus->self->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
349 		if (features & PCI_COMMAND_FAST_BACK)
350 			bus->bridge_ctl |= PCI_BRIDGE_CTL_FAST_BACK;
351 		if (features & PCI_COMMAND_PARITY)
352 			bus->bridge_ctl |= PCI_BRIDGE_CTL_PARITY;
353 	}
354 
355 	/*
356 	 * Report what we did for this bus
357 	 */
358 	printk(KERN_INFO "PCI: bus%d: Fast back to back transfers %sabled\n",
359 		bus->number, (features & PCI_COMMAND_FAST_BACK) ? "en" : "dis");
360 }
361 EXPORT_SYMBOL(pcibios_fixup_bus);
362 
363 void pcibios_add_bus(struct pci_bus *bus)
364 {
365 	struct pci_sys_data *sys = bus->sysdata;
366 	if (sys->add_bus)
367 		sys->add_bus(bus);
368 }
369 
370 void pcibios_remove_bus(struct pci_bus *bus)
371 {
372 	struct pci_sys_data *sys = bus->sysdata;
373 	if (sys->remove_bus)
374 		sys->remove_bus(bus);
375 }
376 
377 /*
378  * Swizzle the device pin each time we cross a bridge.  If a platform does
379  * not provide a swizzle function, we perform the standard PCI swizzling.
380  *
381  * The default swizzling walks up the bus tree one level at a time, applying
382  * the standard swizzle function at each step, stopping when it finds the PCI
383  * root bus.  This will return the slot number of the bridge device on the
384  * root bus and the interrupt pin on that device which should correspond
385  * with the downstream device interrupt.
386  *
387  * Platforms may override this, in which case the slot and pin returned
388  * depend entirely on the platform code.  However, please note that the
389  * PCI standard swizzle is implemented on plug-in cards and Cardbus based
390  * PCI extenders, so it can not be ignored.
391  */
392 static u8 pcibios_swizzle(struct pci_dev *dev, u8 *pin)
393 {
394 	struct pci_sys_data *sys = dev->sysdata;
395 	int slot, oldpin = *pin;
396 
397 	if (sys->swizzle)
398 		slot = sys->swizzle(dev, pin);
399 	else
400 		slot = pci_common_swizzle(dev, pin);
401 
402 	if (debug_pci)
403 		printk("PCI: %s swizzling pin %d => pin %d slot %d\n",
404 			pci_name(dev), oldpin, *pin, slot);
405 
406 	return slot;
407 }
408 
409 /*
410  * Map a slot/pin to an IRQ.
411  */
412 static int pcibios_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
413 {
414 	struct pci_sys_data *sys = dev->sysdata;
415 	int irq = -1;
416 
417 	if (sys->map_irq)
418 		irq = sys->map_irq(dev, slot, pin);
419 
420 	if (debug_pci)
421 		printk("PCI: %s mapping slot %d pin %d => irq %d\n",
422 			pci_name(dev), slot, pin, irq);
423 
424 	return irq;
425 }
426 
427 static int pcibios_init_resources(int busnr, struct pci_sys_data *sys)
428 {
429 	int ret;
430 	struct pci_host_bridge_window *window;
431 
432 	if (list_empty(&sys->resources)) {
433 		pci_add_resource_offset(&sys->resources,
434 			 &iomem_resource, sys->mem_offset);
435 	}
436 
437 	list_for_each_entry(window, &sys->resources, list) {
438 		if (resource_type(window->res) == IORESOURCE_IO)
439 			return 0;
440 	}
441 
442 	sys->io_res.start = (busnr * SZ_64K) ?  : pcibios_min_io;
443 	sys->io_res.end = (busnr + 1) * SZ_64K - 1;
444 	sys->io_res.flags = IORESOURCE_IO;
445 	sys->io_res.name = sys->io_res_name;
446 	sprintf(sys->io_res_name, "PCI%d I/O", busnr);
447 
448 	ret = request_resource(&ioport_resource, &sys->io_res);
449 	if (ret) {
450 		pr_err("PCI: unable to allocate I/O port region (%d)\n", ret);
451 		return ret;
452 	}
453 	pci_add_resource_offset(&sys->resources, &sys->io_res,
454 				sys->io_offset);
455 
456 	return 0;
457 }
458 
459 static void pcibios_init_hw(struct device *parent, struct hw_pci *hw,
460 			    struct list_head *head)
461 {
462 	struct pci_sys_data *sys = NULL;
463 	int ret;
464 	int nr, busnr;
465 
466 	for (nr = busnr = 0; nr < hw->nr_controllers; nr++) {
467 		sys = kzalloc(sizeof(struct pci_sys_data), GFP_KERNEL);
468 		if (!sys)
469 			panic("PCI: unable to allocate sys data!");
470 
471 #ifdef CONFIG_PCI_DOMAINS
472 		sys->domain  = hw->domain;
473 #endif
474 		sys->busnr   = busnr;
475 		sys->swizzle = hw->swizzle;
476 		sys->map_irq = hw->map_irq;
477 		sys->align_resource = hw->align_resource;
478 		sys->add_bus = hw->add_bus;
479 		sys->remove_bus = hw->remove_bus;
480 		INIT_LIST_HEAD(&sys->resources);
481 
482 		if (hw->private_data)
483 			sys->private_data = hw->private_data[nr];
484 
485 		ret = hw->setup(nr, sys);
486 
487 		if (ret > 0) {
488 			ret = pcibios_init_resources(nr, sys);
489 			if (ret)  {
490 				kfree(sys);
491 				break;
492 			}
493 
494 			if (hw->scan)
495 				sys->bus = hw->scan(nr, sys);
496 			else
497 				sys->bus = pci_scan_root_bus(parent, sys->busnr,
498 						hw->ops, sys, &sys->resources);
499 
500 			if (!sys->bus)
501 				panic("PCI: unable to scan bus!");
502 
503 			busnr = sys->bus->busn_res.end + 1;
504 
505 			list_add(&sys->node, head);
506 		} else {
507 			kfree(sys);
508 			if (ret < 0)
509 				break;
510 		}
511 	}
512 }
513 
514 void pci_common_init_dev(struct device *parent, struct hw_pci *hw)
515 {
516 	struct pci_sys_data *sys;
517 	LIST_HEAD(head);
518 
519 	pci_add_flags(PCI_REASSIGN_ALL_RSRC);
520 	if (hw->preinit)
521 		hw->preinit();
522 	pcibios_init_hw(parent, hw, &head);
523 	if (hw->postinit)
524 		hw->postinit();
525 
526 	pci_fixup_irqs(pcibios_swizzle, pcibios_map_irq);
527 
528 	list_for_each_entry(sys, &head, node) {
529 		struct pci_bus *bus = sys->bus;
530 
531 		if (!pci_has_flag(PCI_PROBE_ONLY)) {
532 			/*
533 			 * Size the bridge windows.
534 			 */
535 			pci_bus_size_bridges(bus);
536 
537 			/*
538 			 * Assign resources.
539 			 */
540 			pci_bus_assign_resources(bus);
541 		}
542 
543 		/*
544 		 * Tell drivers about devices found.
545 		 */
546 		pci_bus_add_devices(bus);
547 	}
548 
549 	list_for_each_entry(sys, &head, node) {
550 		struct pci_bus *bus = sys->bus;
551 
552 		/* Configure PCI Express settings */
553 		if (bus && !pci_has_flag(PCI_PROBE_ONLY)) {
554 			struct pci_bus *child;
555 
556 			list_for_each_entry(child, &bus->children, node)
557 				pcie_bus_configure_settings(child);
558 		}
559 	}
560 }
561 
562 #ifndef CONFIG_PCI_HOST_ITE8152
563 void pcibios_set_master(struct pci_dev *dev)
564 {
565 	/* No special bus mastering setup handling */
566 }
567 #endif
568 
569 char * __init pcibios_setup(char *str)
570 {
571 	if (!strcmp(str, "debug")) {
572 		debug_pci = 1;
573 		return NULL;
574 	} else if (!strcmp(str, "firmware")) {
575 		pci_add_flags(PCI_PROBE_ONLY);
576 		return NULL;
577 	}
578 	return str;
579 }
580 
581 /*
582  * From arch/i386/kernel/pci-i386.c:
583  *
584  * We need to avoid collisions with `mirrored' VGA ports
585  * and other strange ISA hardware, so we always want the
586  * addresses to be allocated in the 0x000-0x0ff region
587  * modulo 0x400.
588  *
589  * Why? Because some silly external IO cards only decode
590  * the low 10 bits of the IO address. The 0x00-0xff region
591  * is reserved for motherboard devices that decode all 16
592  * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
593  * but we want to try to avoid allocating at 0x2900-0x2bff
594  * which might be mirrored at 0x0100-0x03ff..
595  */
596 resource_size_t pcibios_align_resource(void *data, const struct resource *res,
597 				resource_size_t size, resource_size_t align)
598 {
599 	struct pci_dev *dev = data;
600 	struct pci_sys_data *sys = dev->sysdata;
601 	resource_size_t start = res->start;
602 
603 	if (res->flags & IORESOURCE_IO && start & 0x300)
604 		start = (start + 0x3ff) & ~0x3ff;
605 
606 	start = (start + align - 1) & ~(align - 1);
607 
608 	if (sys->align_resource)
609 		return sys->align_resource(dev, res, start, size, align);
610 
611 	return start;
612 }
613 
614 /**
615  * pcibios_enable_device - Enable I/O and memory.
616  * @dev: PCI device to be enabled
617  */
618 int pcibios_enable_device(struct pci_dev *dev, int mask)
619 {
620 	if (pci_has_flag(PCI_PROBE_ONLY))
621 		return 0;
622 
623 	return pci_enable_resources(dev, mask);
624 }
625 
626 int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
627 			enum pci_mmap_state mmap_state, int write_combine)
628 {
629 	struct pci_sys_data *root = dev->sysdata;
630 	unsigned long phys;
631 
632 	if (mmap_state == pci_mmap_io) {
633 		return -EINVAL;
634 	} else {
635 		phys = vma->vm_pgoff + (root->mem_offset >> PAGE_SHIFT);
636 	}
637 
638 	/*
639 	 * Mark this as IO
640 	 */
641 	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
642 
643 	if (remap_pfn_range(vma, vma->vm_start, phys,
644 			     vma->vm_end - vma->vm_start,
645 			     vma->vm_page_prot))
646 		return -EAGAIN;
647 
648 	return 0;
649 }
650 
651 void __init pci_map_io_early(unsigned long pfn)
652 {
653 	struct map_desc pci_io_desc = {
654 		.virtual	= PCI_IO_VIRT_BASE,
655 		.type		= MT_DEVICE,
656 		.length		= SZ_64K,
657 	};
658 
659 	pci_io_desc.pfn = pfn;
660 	iotable_init(&pci_io_desc, 1);
661 }
662