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 */
  83size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size)
  84{
  85        void __iomem *image;
  86        int last_image;
  87        unsigned length;
  88
  89        image = rom;
  90        do {
  91                void __iomem *pds;
  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",
  95                                 readw(image));
  96                        break;
  97                }
  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",
 102                                 readl(pds));
 103                        break;
 104                }
 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)
 110                        break;
 111        } while (length && !last_image);
 112
 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);
 116}
 117
 118/**
 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
 122 *
 123 * Return: kernel virtual pointer to image of ROM
 124 *
 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
 127 * actual ROM.
 128 */
 129void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
 130{
 131        struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 132        loff_t start;
 133        void __iomem *rom;
 134
 135        /* assign the ROM an address if it doesn't have one */
 136        if (res->parent == NULL && pci_assign_resource(pdev, PCI_ROM_RESOURCE))
 137                return NULL;
 138
 139        start = pci_resource_start(pdev, PCI_ROM_RESOURCE);
 140        *size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
 141        if (*size == 0)
 142                return NULL;
 143
 144        /* Enable ROM space decodes */
 145        if (pci_enable_rom(pdev))
 146                return NULL;
 147
 148        rom = ioremap(start, *size);
 149        if (!rom)
 150                goto err_ioremap;
 151
 152        /*
 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.
 156         */
 157        *size = pci_get_rom_size(pdev, rom, *size);
 158        if (!*size)
 159                goto invalid_rom;
 160
 161        return rom;
 162
 163invalid_rom:
 164        iounmap(rom);
 165err_ioremap:
 166        /* restore enable if ioremap fails */
 167        if (!(res->flags & IORESOURCE_ROM_ENABLE))
 168                pci_disable_rom(pdev);
 169        return NULL;
 170}
 171EXPORT_SYMBOL(pci_map_rom);
 172
 173/**
 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
 177 *
 178 * Remove a mapping of a previously mapped ROM
 179 */
 180void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
 181{
 182        struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 183
 184        iounmap(rom);
 185
 186        /* Disable again before continuing */
 187        if (!(res->flags & IORESOURCE_ROM_ENABLE))
 188                pci_disable_rom(pdev);
 189}
 190EXPORT_SYMBOL(pci_unmap_rom);
 191
 192/**
 193 * pci_platform_rom - provides a pointer to any ROM image provided by the
 194 * platform
 195 * @pdev: pointer to pci device struct
 196 * @size: pointer to receive size of pci window over ROM
 197 */
 198void __iomem *pci_platform_rom(struct pci_dev *pdev, size_t *size)
 199{
 200        if (pdev->rom && pdev->romlen) {
 201                *size = pdev->romlen;
 202                return phys_to_virt((phys_addr_t)pdev->rom);
 203        }
 204
 205        return NULL;
 206}
 207EXPORT_SYMBOL(pci_platform_rom);
 208