1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * PCI ROM access routines |
4 | * |
5 | * (C) Copyright 2004 Jon Smirl <jonsmirl@yahoo.com> |
6 | * (C) Copyright 2004 Silicon Graphics, Inc. Jesse Barnes <jbarnes@sgi.com> |
7 | */ |
8 | #include <linux/kernel.h> |
9 | #include <linux/export.h> |
10 | #include <linux/pci.h> |
11 | #include <linux/slab.h> |
12 | |
13 | #include "pci.h" |
14 | |
15 | /** |
16 | * pci_enable_rom - enable ROM decoding for a PCI device |
17 | * @pdev: PCI device to enable |
18 | * |
19 | * Enable ROM decoding on @dev. This involves simply turning on the last |
20 | * bit of the PCI ROM BAR. Note that some cards may share address decoders |
21 | * between the ROM and other resources, so enabling it may disable access |
22 | * to MMIO registers or other card memory. |
23 | */ |
24 | int pci_enable_rom(struct pci_dev *pdev) |
25 | { |
26 | struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; |
27 | struct pci_bus_region region; |
28 | u32 rom_addr; |
29 | |
30 | if (!res->flags) |
31 | return -1; |
32 | |
33 | /* Nothing to enable if we're using a shadow copy in RAM */ |
34 | if (res->flags & IORESOURCE_ROM_SHADOW) |
35 | return 0; |
36 | |
37 | /* |
38 | * Ideally pci_update_resource() would update the ROM BAR address, |
39 | * and we would only set the enable bit here. But apparently some |
40 | * devices have buggy ROM BARs that read as zero when disabled. |
41 | */ |
42 | pcibios_resource_to_bus(bus: pdev->bus, region: ®ion, res); |
43 | pci_read_config_dword(dev: pdev, where: pdev->rom_base_reg, val: &rom_addr); |
44 | rom_addr &= ~PCI_ROM_ADDRESS_MASK; |
45 | rom_addr |= region.start | PCI_ROM_ADDRESS_ENABLE; |
46 | pci_write_config_dword(dev: pdev, where: pdev->rom_base_reg, val: rom_addr); |
47 | return 0; |
48 | } |
49 | EXPORT_SYMBOL_GPL(pci_enable_rom); |
50 | |
51 | /** |
52 | * pci_disable_rom - disable ROM decoding for a PCI device |
53 | * @pdev: PCI device to disable |
54 | * |
55 | * Disable ROM decoding on a PCI device by turning off the last bit in the |
56 | * ROM BAR. |
57 | */ |
58 | void pci_disable_rom(struct pci_dev *pdev) |
59 | { |
60 | struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; |
61 | u32 rom_addr; |
62 | |
63 | if (res->flags & IORESOURCE_ROM_SHADOW) |
64 | return; |
65 | |
66 | pci_read_config_dword(dev: pdev, where: pdev->rom_base_reg, val: &rom_addr); |
67 | rom_addr &= ~PCI_ROM_ADDRESS_ENABLE; |
68 | pci_write_config_dword(dev: pdev, where: pdev->rom_base_reg, val: rom_addr); |
69 | } |
70 | EXPORT_SYMBOL_GPL(pci_disable_rom); |
71 | |
72 | /** |
73 | * pci_get_rom_size - obtain the actual size of the ROM image |
74 | * @pdev: target PCI device |
75 | * @rom: kernel virtual pointer to image of ROM |
76 | * @size: size of PCI window |
77 | * return: size of actual ROM image |
78 | * |
79 | * Determine the actual length of the ROM image. |
80 | * The PCI window size could be much larger than the |
81 | * actual image size. |
82 | */ |
83 | static size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, |
84 | size_t size) |
85 | { |
86 | void __iomem *image; |
87 | int last_image; |
88 | unsigned int length; |
89 | |
90 | image = rom; |
91 | do { |
92 | void __iomem *pds; |
93 | /* Standard PCI ROMs start out with these bytes 55 AA */ |
94 | if (readw(addr: image) != 0xAA55) { |
95 | pci_info(pdev, "Invalid PCI ROM header signature: expecting 0xaa55, got %#06x\n" , |
96 | readw(image)); |
97 | break; |
98 | } |
99 | /* get the PCI data structure and check its "PCIR" signature */ |
100 | pds = image + readw(addr: image + 24); |
101 | if (readl(addr: pds) != 0x52494350) { |
102 | pci_info(pdev, "Invalid PCI ROM data signature: expecting 0x52494350, got %#010x\n" , |
103 | readl(pds)); |
104 | break; |
105 | } |
106 | last_image = readb(addr: pds + 21) & 0x80; |
107 | length = readw(addr: pds + 16); |
108 | image += length * 512; |
109 | /* Avoid iterating through memory outside the resource window */ |
110 | if (image >= rom + size) |
111 | break; |
112 | if (!last_image) { |
113 | if (readw(addr: image) != 0xAA55) { |
114 | pci_info(pdev, "No more image in the PCI ROM\n" ); |
115 | break; |
116 | } |
117 | } |
118 | } while (length && !last_image); |
119 | |
120 | /* never return a size larger than the PCI resource window */ |
121 | /* there are known ROMs that get the size wrong */ |
122 | return min((size_t)(image - rom), size); |
123 | } |
124 | |
125 | /** |
126 | * pci_map_rom - map a PCI ROM to kernel space |
127 | * @pdev: pointer to pci device struct |
128 | * @size: pointer to receive size of pci window over ROM |
129 | * |
130 | * Return: kernel virtual pointer to image of ROM |
131 | * |
132 | * Map a PCI ROM into kernel space. If ROM is boot video ROM, |
133 | * the shadow BIOS copy will be returned instead of the |
134 | * actual ROM. |
135 | */ |
136 | void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size) |
137 | { |
138 | struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; |
139 | loff_t start; |
140 | void __iomem *rom; |
141 | |
142 | /* assign the ROM an address if it doesn't have one */ |
143 | if (res->parent == NULL && pci_assign_resource(dev: pdev, i: PCI_ROM_RESOURCE)) |
144 | return NULL; |
145 | |
146 | start = pci_resource_start(pdev, PCI_ROM_RESOURCE); |
147 | *size = pci_resource_len(pdev, PCI_ROM_RESOURCE); |
148 | if (*size == 0) |
149 | return NULL; |
150 | |
151 | /* Enable ROM space decodes */ |
152 | if (pci_enable_rom(pdev)) |
153 | return NULL; |
154 | |
155 | rom = ioremap(offset: start, size: *size); |
156 | if (!rom) |
157 | goto err_ioremap; |
158 | |
159 | /* |
160 | * Try to find the true size of the ROM since sometimes the PCI window |
161 | * size is much larger than the actual size of the ROM. |
162 | * True size is important if the ROM is going to be copied. |
163 | */ |
164 | *size = pci_get_rom_size(pdev, rom, size: *size); |
165 | if (!*size) |
166 | goto invalid_rom; |
167 | |
168 | return rom; |
169 | |
170 | invalid_rom: |
171 | iounmap(addr: rom); |
172 | err_ioremap: |
173 | /* restore enable if ioremap fails */ |
174 | if (!(res->flags & IORESOURCE_ROM_ENABLE)) |
175 | pci_disable_rom(pdev); |
176 | return NULL; |
177 | } |
178 | EXPORT_SYMBOL(pci_map_rom); |
179 | |
180 | /** |
181 | * pci_unmap_rom - unmap the ROM from kernel space |
182 | * @pdev: pointer to pci device struct |
183 | * @rom: virtual address of the previous mapping |
184 | * |
185 | * Remove a mapping of a previously mapped ROM |
186 | */ |
187 | void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom) |
188 | { |
189 | struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; |
190 | |
191 | iounmap(addr: rom); |
192 | |
193 | /* Disable again before continuing */ |
194 | if (!(res->flags & IORESOURCE_ROM_ENABLE)) |
195 | pci_disable_rom(pdev); |
196 | } |
197 | EXPORT_SYMBOL(pci_unmap_rom); |
198 | |