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1// SPDX-License-Identifier: GPL-2.02/*3 * PCI ROM access routines4 *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 device17 * @pdev: PCI device to enable18 *19 * Enable ROM decoding on @dev. This involves simply turning on the last20 * bit of the PCI ROM BAR. Note that some cards may share address decoders21 * between the ROM and other resources, so enabling it may disable access22 * to MMIO registers or other card memory.23 */24int 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 some40 * devices have buggy ROM BARs that read as zero when disabled.41 */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);47 return 0;48}49EXPORT_SYMBOL_GPL(pci_enable_rom);50 51/**52 * pci_disable_rom - disable ROM decoding for a PCI device53 * @pdev: PCI device to disable54 *55 * Disable ROM decoding on a PCI device by turning off the last bit in the56 * ROM BAR.57 */58void 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(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);69}70EXPORT_SYMBOL_GPL(pci_disable_rom);71 72/**73 * pci_get_rom_size - obtain the actual size of the ROM image74 * @pdev: target PCI device75 * @rom: kernel virtual pointer to image of ROM76 * @size: size of PCI window77 * return: size of actual ROM image78 *79 * Determine the actual length of the ROM image.80 * The PCI window size could be much larger than the81 * actual image size.82 */83static 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(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(image + 24);101 if (readl(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(pds + 21) & 0x80;107 length = readw(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(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 space127 * @pdev: pointer to pci device struct128 * @size: pointer to receive size of pci window over ROM129 *130 * Return: kernel virtual pointer to image of ROM131 *132 * Map a PCI ROM into kernel space. If ROM is boot video ROM,133 * the shadow BIOS copy will be returned instead of the134 * actual ROM.135 */136void __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(pdev, 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(start, *size);156 if (!rom)157 goto err_ioremap;158 159 /*160 * Try to find the true size of the ROM since sometimes the PCI window161 * 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);165 if (!*size)166 goto invalid_rom;167 168 return rom;169 170invalid_rom:171 iounmap(rom);172err_ioremap:173 /* restore enable if ioremap fails */174 if (!(res->flags & IORESOURCE_ROM_ENABLE))175 pci_disable_rom(pdev);176 return NULL;177}178EXPORT_SYMBOL(pci_map_rom);179 180/**181 * pci_unmap_rom - unmap the ROM from kernel space182 * @pdev: pointer to pci device struct183 * @rom: virtual address of the previous mapping184 *185 * Remove a mapping of a previously mapped ROM186 */187void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)188{189 struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];190 191 iounmap(rom);192 193 /* Disable again before continuing */194 if (!(res->flags & IORESOURCE_ROM_ENABLE))195 pci_disable_rom(pdev);196}197EXPORT_SYMBOL(pci_unmap_rom);198