1 // SPDX-License-Identifier: GPL-2.0
3 * PCI ROM access routines
5 * (C) Copyright 2004 Jon Smirl <jonsmirl@yahoo.com>
6 * (C) Copyright 2004 Silicon Graphics, Inc. Jesse Barnes <jbarnes@sgi.com>
8 #include <linux/kernel.h>
9 #include <linux/export.h>
10 #include <linux/pci.h>
11 #include <linux/slab.h>
16 * pci_enable_rom - enable ROM decoding for a PCI device
17 * @pdev: PCI device to enable
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.
24 int pci_enable_rom(struct pci_dev
*pdev
)
26 struct resource
*res
= &pdev
->resource
[PCI_ROM_RESOURCE
];
27 struct pci_bus_region region
;
33 /* Nothing to enable if we're using a shadow copy in RAM */
34 if (res
->flags
& IORESOURCE_ROM_SHADOW
)
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.
42 pcibios_resource_to_bus(pdev
->bus
, ®ion
, res
);
43 pci_read_config_dword(pdev
, pdev
->rom_base_reg
, &rom_addr
);
44 rom_addr
&= ~PCI_ROM_ADDRESS_MASK
;
45 rom_addr
|= region
.start
| PCI_ROM_ADDRESS_ENABLE
;
46 pci_write_config_dword(pdev
, pdev
->rom_base_reg
, rom_addr
);
49 EXPORT_SYMBOL_GPL(pci_enable_rom
);
52 * pci_disable_rom - disable ROM decoding for a PCI device
53 * @pdev: PCI device to disable
55 * Disable ROM decoding on a PCI device by turning off the last bit in the
58 void pci_disable_rom(struct pci_dev
*pdev
)
60 struct resource
*res
= &pdev
->resource
[PCI_ROM_RESOURCE
];
63 if (res
->flags
& IORESOURCE_ROM_SHADOW
)
66 pci_read_config_dword(pdev
, pdev
->rom_base_reg
, &rom_addr
);
67 rom_addr
&= ~PCI_ROM_ADDRESS_ENABLE
;
68 pci_write_config_dword(pdev
, pdev
->rom_base_reg
, rom_addr
);
70 EXPORT_SYMBOL_GPL(pci_disable_rom
);
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
79 * Determine the actual length of the ROM image.
80 * The PCI window size could be much larger than the
83 size_t pci_get_rom_size(struct pci_dev
*pdev
, void __iomem
*rom
, size_t size
)
92 /* Standard PCI ROMs start out with these bytes 55 AA */
93 if (readw(image
) != 0xAA55) {
94 pci_info(pdev
, "Invalid PCI ROM header signature: expecting 0xaa55, got %#06x\n",
98 /* get the PCI data structure and check its "PCIR" signature */
99 pds
= image
+ readw(image
+ 24);
100 if (readl(pds
) != 0x52494350) {
101 pci_info(pdev
, "Invalid PCI ROM data signature: expecting 0x52494350, got %#010x\n",
105 last_image
= readb(pds
+ 21) & 0x80;
106 length
= readw(pds
+ 16);
107 image
+= length
* 512;
108 /* Avoid iterating through memory outside the resource window */
109 if (image
> rom
+ size
)
111 } while (length
&& !last_image
);
113 /* never return a size larger than the PCI resource window */
114 /* there are known ROMs that get the size wrong */
115 return min((size_t)(image
- rom
), size
);
119 * pci_map_rom - map a PCI ROM to kernel space
120 * @pdev: pointer to pci device struct
121 * @size: pointer to receive size of pci window over ROM
123 * Return: kernel virtual pointer to image of ROM
125 * Map a PCI ROM into kernel space. If ROM is boot video ROM,
126 * the shadow BIOS copy will be returned instead of the
129 void __iomem
*pci_map_rom(struct pci_dev
*pdev
, size_t *size
)
131 struct resource
*res
= &pdev
->resource
[PCI_ROM_RESOURCE
];
135 /* assign the ROM an address if it doesn't have one */
136 if (res
->parent
== NULL
&& pci_assign_resource(pdev
, PCI_ROM_RESOURCE
))
139 start
= pci_resource_start(pdev
, PCI_ROM_RESOURCE
);
140 *size
= pci_resource_len(pdev
, PCI_ROM_RESOURCE
);
144 /* Enable ROM space decodes */
145 if (pci_enable_rom(pdev
))
148 rom
= ioremap(start
, *size
);
153 * Try to find the true size of the ROM since sometimes the PCI window
154 * size is much larger than the actual size of the ROM.
155 * True size is important if the ROM is going to be copied.
157 *size
= pci_get_rom_size(pdev
, rom
, *size
);
166 /* restore enable if ioremap fails */
167 if (!(res
->flags
& IORESOURCE_ROM_ENABLE
))
168 pci_disable_rom(pdev
);
171 EXPORT_SYMBOL(pci_map_rom
);
174 * pci_unmap_rom - unmap the ROM from kernel space
175 * @pdev: pointer to pci device struct
176 * @rom: virtual address of the previous mapping
178 * Remove a mapping of a previously mapped ROM
180 void pci_unmap_rom(struct pci_dev
*pdev
, void __iomem
*rom
)
182 struct resource
*res
= &pdev
->resource
[PCI_ROM_RESOURCE
];
186 /* Disable again before continuing */
187 if (!(res
->flags
& IORESOURCE_ROM_ENABLE
))
188 pci_disable_rom(pdev
);
190 EXPORT_SYMBOL(pci_unmap_rom
);
193 * pci_platform_rom - provides a pointer to any ROM image provided by the
195 * @pdev: pointer to pci device struct
196 * @size: pointer to receive size of pci window over ROM
198 void __iomem
*pci_platform_rom(struct pci_dev
*pdev
, size_t *size
)
200 if (pdev
->rom
&& pdev
->romlen
) {
201 *size
= pdev
->romlen
;
202 return phys_to_virt((phys_addr_t
)pdev
->rom
);
207 EXPORT_SYMBOL(pci_platform_rom
);