2 * Low-Level PCI Access for i386 machines
4 * Copyright 1993, 1994 Drew Eckhardt
6 * (Unix and Linux consulting and custom programming)
10 * Drew's work was sponsored by:
11 * iX Multiuser Multitasking Magazine
15 * Copyright 1997--2000 Martin Mares <mj@suse.cz>
17 * For more information, please consult the following manuals (look at
18 * http://www.pcisig.com/ for how to get them):
20 * PCI BIOS Specification
21 * PCI Local Bus Specification
22 * PCI to PCI Bridge Specification
23 * PCI System Design Guide
27 * Jun 17, 1994 : Modified to accommodate the broken pre-PCI BIOS SPECIFICATION
28 * Revision 2.0 present on <thys@dennis.ee.up.ac.za>'s ASUS mainboard.
30 * Jan 5, 1995 : Modified to probe PCI hardware at boot time by Frederic
31 * Potter, potter@cao-vlsi.ibp.fr
33 * Jan 10, 1995 : Modified to store the information about configured pci
34 * devices into a list, which can be accessed via /proc/pci by
35 * Curtis Varner, cvarner@cs.ucr.edu
37 * Jan 12, 1995 : CPU-PCI bridge optimization support by Frederic Potter.
38 * Alpha version. Intel & UMC chipset support only.
40 * Apr 16, 1995 : Source merge with the DEC Alpha PCI support. Most of the code
41 * moved to drivers/pci/pci.c.
43 * Dec 7, 1996 : Added support for direct configuration access of boards
44 * with Intel compatible access schemes (tsbogend@alpha.franken.de)
46 * Feb 3, 1997 : Set internal functions to static, save/restore flags
47 * avoid dead locks reading broken PCI BIOS, werner@suse.de
49 * Apr 26, 1997 : Fixed case when there is BIOS32, but not PCI BIOS
50 * (mj@atrey.karlin.mff.cuni.cz)
52 * May 7, 1997 : Added some missing cli()'s. [mj]
54 * Jun 20, 1997 : Corrected problems in "conf1" type accesses.
57 * Aug 2, 1997 : Split to PCI BIOS handling and direct PCI access parts
58 * and cleaned it up... Martin Mares <mj@atrey.karlin.mff.cuni.cz>
60 * Feb 6, 1998 : No longer using BIOS to find devices and device classes. [mj]
62 * May 1, 1998 : Support for peer host bridges. [mj]
64 * Jun 19, 1998 : Changed to use spinlocks, so that PCI configuration space
65 * can be accessed from interrupts even on SMP systems. [mj]
67 * August 1998 : Better support for peer host bridges and more paranoid
68 * checks for direct hardware access. Ugh, this file starts to look as
69 * a large gallery of common hardware bug workarounds (watch the comments)
70 * -- the PCI specs themselves are sane, but most implementors should be
71 * hit hard with \hammer scaled \magstep5. [mj]
73 * Jan 23, 1999 : More improvements to peer host bridge logic. i450NX fixup. [mj]
75 * Feb 8, 1999 : Added UM8886BF I/O address fixup. [mj]
77 * August 1999 : New resource management and configuration access stuff. [mj]
79 * Sep 19, 1999 : Use PCI IRQ routing tables for detection of peer host bridges.
80 * Based on ideas by Chris Frantz and David Hinds. [mj]
82 * Sep 28, 1999 : Handle unreported/unassigned IRQs. Thanks to Shuu Yamaguchi
83 * for a lot of patience during testing. [mj]
85 * Oct 8, 1999 : Split to pci-i386.c, pci-pc.c and pci-visws.c. [mj]
88 #include <linux/types.h>
89 #include <linux/kernel.h>
90 #include <linux/pci.h>
91 #include <linux/init.h>
92 #include <linux/ioport.h>
93 #include <linux/errno.h>
98 pcibios_update_resource(struct pci_dev
*dev
, struct resource
*root
,
99 struct resource
*res
, int resource
)
104 new = res
->start
| (res
->flags
& PCI_REGION_FLAG_MASK
);
106 reg
= PCI_BASE_ADDRESS_0
+ 4*resource
;
107 } else if (resource
== PCI_ROM_RESOURCE
) {
108 res
->flags
|= PCI_ROM_ADDRESS_ENABLE
;
109 new |= PCI_ROM_ADDRESS_ENABLE
;
110 reg
= dev
->rom_base_reg
;
112 /* Somebody might have asked allocation of a non-standard resource */
116 pci_write_config_dword(dev
, reg
, new);
117 pci_read_config_dword(dev
, reg
, &check
);
118 if ((new ^ check
) & ((new & PCI_BASE_ADDRESS_SPACE_IO
) ? PCI_BASE_ADDRESS_IO_MASK
: PCI_BASE_ADDRESS_MEM_MASK
)) {
119 printk(KERN_ERR
"PCI: Error while updating region "
120 "%s/%d (%08x != %08x)\n", dev
->slot_name
, resource
,
126 * We need to avoid collisions with `mirrored' VGA ports
127 * and other strange ISA hardware, so we always want the
128 * addresses to be allocated in the 0x000-0x0ff region
131 * Why? Because some silly external IO cards only decode
132 * the low 10 bits of the IO address. The 0x00-0xff region
133 * is reserved for motherboard devices that decode all 16
134 * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
135 * but we want to try to avoid allocating at 0x2900-0x2bff
136 * which might have be mirrored at 0x0100-0x03ff..
139 pcibios_align_resource(void *data
, struct resource
*res
, unsigned long size
)
141 if (res
->flags
& IORESOURCE_IO
) {
142 unsigned long start
= res
->start
;
145 start
= (start
+ 0x3ff) & ~0x3ff;
153 * Handle resources of PCI devices. If the world were perfect, we could
154 * just allocate all the resource regions and do nothing more. It isn't.
155 * On the other hand, we cannot just re-allocate all devices, as it would
156 * require us to know lots of host bridge internals. So we attempt to
157 * keep as much of the original configuration as possible, but tweak it
158 * when it's found to be wrong.
160 * Known BIOS problems we have to work around:
161 * - I/O or memory regions not configured
162 * - regions configured, but not enabled in the command register
163 * - bogus I/O addresses above 64K used
164 * - expansion ROMs left enabled (this may sound harmless, but given
165 * the fact the PCI specs explicitly allow address decoders to be
166 * shared between expansion ROMs and other resource regions, it's
167 * at least dangerous)
170 * (1) Allocate resources for all buses behind PCI-to-PCI bridges.
171 * This gives us fixed barriers on where we can allocate.
172 * (2) Allocate resources for all enabled devices. If there is
173 * a collision, just mark the resource as unallocated. Also
174 * disable expansion ROMs during this step.
175 * (3) Try to allocate resources for disabled devices. If the
176 * resources were assigned correctly, everything goes well,
177 * if they weren't, they won't disturb allocation of other
179 * (4) Assign new addresses to resources which were either
180 * not configured at all or misconfigured. If explicitly
181 * requested by the user, configure expansion ROM address
185 static void __init
pcibios_allocate_bus_resources(struct list_head
*bus_list
)
187 struct list_head
*ln
;
191 struct resource
*r
, *pr
;
193 /* Depth-First Search on bus tree */
194 for (ln
=bus_list
->next
; ln
!= bus_list
; ln
=ln
->next
) {
196 if ((dev
= bus
->self
)) {
197 for (idx
= PCI_BRIDGE_RESOURCES
; idx
< PCI_NUM_RESOURCES
; idx
++) {
198 r
= &dev
->resource
[idx
];
201 pr
= pci_find_parent_resource(dev
, r
);
202 if (!pr
|| request_resource(pr
, r
) < 0)
203 printk(KERN_ERR
"PCI: Cannot allocate resource region %d of bridge %s\n", idx
, dev
->slot_name
);
206 pcibios_allocate_bus_resources(&bus
->children
);
210 static void __init
pcibios_allocate_resources(int pass
)
215 struct resource
*r
, *pr
;
217 pci_for_each_dev(dev
) {
218 pci_read_config_word(dev
, PCI_COMMAND
, &command
);
219 for(idx
= 0; idx
< 6; idx
++) {
220 r
= &dev
->resource
[idx
];
221 if (r
->parent
) /* Already allocated */
223 if (!r
->start
) /* Address not assigned at all */
225 if (r
->flags
& IORESOURCE_IO
)
226 disabled
= !(command
& PCI_COMMAND_IO
);
228 disabled
= !(command
& PCI_COMMAND_MEMORY
);
229 if (pass
== disabled
) {
230 DBG("PCI: Resource %08lx-%08lx (f=%lx, d=%d, p=%d)\n",
231 r
->start
, r
->end
, r
->flags
, disabled
, pass
);
232 pr
= pci_find_parent_resource(dev
, r
);
233 if (!pr
|| request_resource(pr
, r
) < 0) {
234 printk(KERN_ERR
"PCI: Cannot allocate resource region %d of device %s\n", idx
, dev
->slot_name
);
235 /* We'll assign a new address later */
242 r
= &dev
->resource
[PCI_ROM_RESOURCE
];
243 if (r
->flags
& PCI_ROM_ADDRESS_ENABLE
) {
244 /* Turn the ROM off, leave the resource region, but keep it unregistered. */
246 DBG("PCI: Switching off ROM of %s\n", dev
->slot_name
);
247 r
->flags
&= ~PCI_ROM_ADDRESS_ENABLE
;
248 pci_read_config_dword(dev
, dev
->rom_base_reg
, ®
);
249 pci_write_config_dword(dev
, dev
->rom_base_reg
, reg
& ~PCI_ROM_ADDRESS_ENABLE
);
255 static void __init
pcibios_assign_resources(void)
261 pci_for_each_dev(dev
) {
262 int class = dev
->class >> 8;
264 /* Don't touch classless devices and host bridges */
265 if (!class || class == PCI_CLASS_BRIDGE_HOST
)
268 for(idx
=0; idx
<6; idx
++) {
269 r
= &dev
->resource
[idx
];
272 * Don't touch IDE controllers and I/O ports of video cards!
274 if ((class == PCI_CLASS_STORAGE_IDE
&& idx
< 4) ||
275 (class == PCI_CLASS_DISPLAY_VGA
&& (r
->flags
& IORESOURCE_IO
)))
279 * We shall assign a new address to this resource, either because
280 * the BIOS forgot to do so or because we have decided the old
281 * address was unusable for some reason.
283 if (!r
->start
&& r
->end
)
284 pci_assign_resource(dev
, idx
);
287 if (pci_probe
& PCI_ASSIGN_ROMS
) {
288 r
= &dev
->resource
[PCI_ROM_RESOURCE
];
292 pci_assign_resource(dev
, PCI_ROM_RESOURCE
);
297 void __init
pcibios_resource_survey(void)
299 DBG("PCI: Allocating resources\n");
300 pcibios_allocate_bus_resources(&pci_root_buses
);
301 pcibios_allocate_resources(0);
302 pcibios_allocate_resources(1);
303 pcibios_assign_resources();
306 int pcibios_enable_resources(struct pci_dev
*dev
)
312 pci_read_config_word(dev
, PCI_COMMAND
, &cmd
);
314 for(idx
=0; idx
<6; idx
++) {
315 r
= &dev
->resource
[idx
];
316 if (!r
->start
&& r
->end
) {
317 printk(KERN_ERR
"PCI: Device %s not available because of resource collisions\n", dev
->slot_name
);
320 if (r
->flags
& IORESOURCE_IO
)
321 cmd
|= PCI_COMMAND_IO
;
322 if (r
->flags
& IORESOURCE_MEM
)
323 cmd
|= PCI_COMMAND_MEMORY
;
325 if (dev
->resource
[PCI_ROM_RESOURCE
].start
)
326 cmd
|= PCI_COMMAND_MEMORY
;
327 if (cmd
!= old_cmd
) {
328 printk("PCI: Enabling device %s (%04x -> %04x)\n", dev
->slot_name
, old_cmd
, cmd
);
329 pci_write_config_word(dev
, PCI_COMMAND
, cmd
);
335 * If we set up a device for bus mastering, we need to check the latency
336 * timer as certain crappy BIOSes forget to set it properly.
338 unsigned int pcibios_max_latency
= 255;
340 void pcibios_set_master(struct pci_dev
*dev
)
343 pci_read_config_byte(dev
, PCI_LATENCY_TIMER
, &lat
);
345 lat
= (64 <= pcibios_max_latency
) ? 64 : pcibios_max_latency
;
346 else if (lat
> pcibios_max_latency
)
347 lat
= pcibios_max_latency
;
350 printk("PCI: Setting latency timer of device %s to %d\n", dev
->slot_name
, lat
);
351 pci_write_config_byte(dev
, PCI_LATENCY_TIMER
, lat
);