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pci-frv.c
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1 /* pci-frv.c: low-level PCI access routines
2  *
3  * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
4  * Written by David Howells ([email protected])
5  * - Derived from the i386 equivalent stuff
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * as published by the Free Software Foundation; either version
10  * 2 of the License, or (at your option) any later version.
11  */
12 
13 #include <linux/types.h>
14 #include <linux/kernel.h>
15 #include <linux/pci.h>
16 #include <linux/init.h>
17 #include <linux/ioport.h>
18 #include <linux/errno.h>
19 
20 #include "pci-frv.h"
21 
22 /*
23  * We need to avoid collisions with `mirrored' VGA ports
24  * and other strange ISA hardware, so we always want the
25  * addresses to be allocated in the 0x000-0x0ff region
26  * modulo 0x400.
27  *
28  * Why? Because some silly external IO cards only decode
29  * the low 10 bits of the IO address. The 0x00-0xff region
30  * is reserved for motherboard devices that decode all 16
31  * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
32  * but we want to try to avoid allocating at 0x2900-0x2bff
33  * which might have be mirrored at 0x0100-0x03ff..
34  */
36 pcibios_align_resource(void *data, const struct resource *res,
38 {
40 
41  if ((res->flags & IORESOURCE_IO) && (start & 0x300))
42  start = (start + 0x3ff) & ~0x3ff;
43 
44  return start;
45 }
46 
47 
48 /*
49  * Handle resources of PCI devices. If the world were perfect, we could
50  * just allocate all the resource regions and do nothing more. It isn't.
51  * On the other hand, we cannot just re-allocate all devices, as it would
52  * require us to know lots of host bridge internals. So we attempt to
53  * keep as much of the original configuration as possible, but tweak it
54  * when it's found to be wrong.
55  *
56  * Known BIOS problems we have to work around:
57  * - I/O or memory regions not configured
58  * - regions configured, but not enabled in the command register
59  * - bogus I/O addresses above 64K used
60  * - expansion ROMs left enabled (this may sound harmless, but given
61  * the fact the PCI specs explicitly allow address decoders to be
62  * shared between expansion ROMs and other resource regions, it's
63  * at least dangerous)
64  *
65  * Our solution:
66  * (1) Allocate resources for all buses behind PCI-to-PCI bridges.
67  * This gives us fixed barriers on where we can allocate.
68  * (2) Allocate resources for all enabled devices. If there is
69  * a collision, just mark the resource as unallocated. Also
70  * disable expansion ROMs during this step.
71  * (3) Try to allocate resources for disabled devices. If the
72  * resources were assigned correctly, everything goes well,
73  * if they weren't, they won't disturb allocation of other
74  * resources.
75  * (4) Assign new addresses to resources which were either
76  * not configured at all or misconfigured. If explicitly
77  * requested by the user, configure expansion ROM address
78  * as well.
79  */
80 
81 static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
82 {
83  struct list_head *ln;
84  struct pci_bus *bus;
85  struct pci_dev *dev;
86  int idx;
87  struct resource *r;
88 
89  /* Depth-First Search on bus tree */
90  for (ln=bus_list->next; ln != bus_list; ln=ln->next) {
91  bus = pci_bus_b(ln);
92  if ((dev = bus->self)) {
93  for (idx = PCI_BRIDGE_RESOURCES; idx < PCI_NUM_RESOURCES; idx++) {
94  r = &dev->resource[idx];
95  if (!r->start)
96  continue;
97  pci_claim_resource(dev, idx);
98  }
99  }
100  pcibios_allocate_bus_resources(&bus->children);
101  }
102 }
103 
104 static void __init pcibios_allocate_resources(int pass)
105 {
106  struct pci_dev *dev = NULL;
107  int idx, disabled;
108  u16 command;
109  struct resource *r;
110 
111  for_each_pci_dev(dev) {
112  pci_read_config_word(dev, PCI_COMMAND, &command);
113  for(idx = 0; idx < 6; idx++) {
114  r = &dev->resource[idx];
115  if (r->parent) /* Already allocated */
116  continue;
117  if (!r->start) /* Address not assigned at all */
118  continue;
119  if (r->flags & IORESOURCE_IO)
120  disabled = !(command & PCI_COMMAND_IO);
121  else
122  disabled = !(command & PCI_COMMAND_MEMORY);
123  if (pass == disabled) {
124  DBG("PCI: Resource %08lx-%08lx (f=%lx, d=%d, p=%d)\n",
125  r->start, r->end, r->flags, disabled, pass);
126  if (pci_claim_resource(dev, idx) < 0) {
127  /* We'll assign a new address later */
128  r->end -= r->start;
129  r->start = 0;
130  }
131  }
132  }
133  if (!pass) {
134  r = &dev->resource[PCI_ROM_RESOURCE];
135  if (r->flags & IORESOURCE_ROM_ENABLE) {
136  /* Turn the ROM off, leave the resource region, but keep it unregistered. */
137  u32 reg;
138  DBG("PCI: Switching off ROM of %s\n", pci_name(dev));
140  pci_read_config_dword(dev, dev->rom_base_reg, &reg);
141  pci_write_config_dword(dev, dev->rom_base_reg, reg & ~PCI_ROM_ADDRESS_ENABLE);
142  }
143  }
144  }
145 }
146 
147 static void __init pcibios_assign_resources(void)
148 {
149  struct pci_dev *dev = NULL;
150  int idx;
151  struct resource *r;
152 
153  for_each_pci_dev(dev) {
154  int class = dev->class >> 8;
155 
156  /* Don't touch classless devices and host bridges */
157  if (!class || class == PCI_CLASS_BRIDGE_HOST)
158  continue;
159 
160  for(idx=0; idx<6; idx++) {
161  r = &dev->resource[idx];
162 
163  /*
164  * Don't touch IDE controllers and I/O ports of video cards!
165  */
166  if ((class == PCI_CLASS_STORAGE_IDE && idx < 4) ||
167  (class == PCI_CLASS_DISPLAY_VGA && (r->flags & IORESOURCE_IO)))
168  continue;
169 
170  /*
171  * We shall assign a new address to this resource, either because
172  * the BIOS forgot to do so or because we have decided the old
173  * address was unusable for some reason.
174  */
175  if (!r->start && r->end)
176  pci_assign_resource(dev, idx);
177  }
178 
179  if (pci_probe & PCI_ASSIGN_ROMS) {
180  r = &dev->resource[PCI_ROM_RESOURCE];
181  r->end -= r->start;
182  r->start = 0;
183  if (r->end)
185  }
186  }
187 }
188 
190 {
191  DBG("PCI: Allocating resources\n");
192  pcibios_allocate_bus_resources(&pci_root_buses);
193  pcibios_allocate_resources(0);
194  pcibios_allocate_resources(1);
195  pcibios_assign_resources();
196 }