LXR linux/drivers/pci/rom.c

   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 */
  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 some
  40         * devices have buggy ROM BARs that read as zero when disabled.
  41         */
  42        pcibios_resource_to_bus(pdev->bus, &region, 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 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 */
  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 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 */
  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 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 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 */
 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 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);
 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 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 */
 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