linux/drivers/pci/rom.c
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   1/*
   2 * drivers/pci/rom.c
   3 *
   4 * (C) Copyright 2004 Jon Smirl <jonsmirl@yahoo.com>
   5 * (C) Copyright 2004 Silicon Graphics, Inc. Jesse Barnes <jbarnes@sgi.com>
   6 *
   7 * PCI ROM access routines
   8 */
   9#include <linux/kernel.h>
  10#include <linux/export.h>
  11#include <linux/pci.h>
  12#include <linux/slab.h>
  13
  14#include "pci.h"
  15
  16/**
  17 * pci_enable_rom - enable ROM decoding for a PCI device
  18 * @pdev: PCI device to enable
  19 *
  20 * Enable ROM decoding on @dev.  This involves simply turning on the last
  21 * bit of the PCI ROM BAR.  Note that some cards may share address decoders
  22 * between the ROM and other resources, so enabling it may disable access
  23 * to MMIO registers or other card memory.
  24 */
  25int pci_enable_rom(struct pci_dev *pdev)
  26{
  27        struct resource *res = pdev->resource + PCI_ROM_RESOURCE;
  28        struct pci_bus_region region;
  29        u32 rom_addr;
  30
  31        if (!res->flags)
  32                return -1;
  33
  34        pcibios_resource_to_bus(pdev, &region, res);
  35        pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
  36        rom_addr &= ~PCI_ROM_ADDRESS_MASK;
  37        rom_addr |= region.start | PCI_ROM_ADDRESS_ENABLE;
  38        pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
  39        return 0;
  40}
  41
  42/**
  43 * pci_disable_rom - disable ROM decoding for a PCI device
  44 * @pdev: PCI device to disable
  45 *
  46 * Disable ROM decoding on a PCI device by turning off the last bit in the
  47 * ROM BAR.
  48 */
  49void pci_disable_rom(struct pci_dev *pdev)
  50{
  51        u32 rom_addr;
  52        pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
  53        rom_addr &= ~PCI_ROM_ADDRESS_ENABLE;
  54        pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
  55}
  56
  57/**
  58 * pci_get_rom_size - obtain the actual size of the ROM image
  59 * @pdev: target PCI device
  60 * @rom: kernel virtual pointer to image of ROM
  61 * @size: size of PCI window
  62 *  return: size of actual ROM image
  63 *
  64 * Determine the actual length of the ROM image.
  65 * The PCI window size could be much larger than the
  66 * actual image size.
  67 */
  68size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size)
  69{
  70        void __iomem *image;
  71        int last_image;
  72
  73        image = rom;
  74        do {
  75                void __iomem *pds;
  76                /* Standard PCI ROMs start out with these bytes 55 AA */
  77                if (readb(image) != 0x55) {
  78                        dev_err(&pdev->dev, "Invalid ROM contents\n");
  79                        break;
  80                }
  81                if (readb(image + 1) != 0xAA)
  82                        break;
  83                /* get the PCI data structure and check its signature */
  84                pds = image + readw(image + 24);
  85                if (readb(pds) != 'P')
  86                        break;
  87                if (readb(pds + 1) != 'C')
  88                        break;
  89                if (readb(pds + 2) != 'I')
  90                        break;
  91                if (readb(pds + 3) != 'R')
  92                        break;
  93                last_image = readb(pds + 21) & 0x80;
  94                /* this length is reliable */
  95                image += readw(pds + 16) * 512;
  96        } while (!last_image);
  97
  98        /* never return a size larger than the PCI resource window */
  99        /* there are known ROMs that get the size wrong */
 100        return min((size_t)(image - rom), size);
 101}
 102
 103/**
 104 * pci_map_rom - map a PCI ROM to kernel space
 105 * @pdev: pointer to pci device struct
 106 * @size: pointer to receive size of pci window over ROM
 107 *
 108 * Return: kernel virtual pointer to image of ROM
 109 *
 110 * Map a PCI ROM into kernel space. If ROM is boot video ROM,
 111 * the shadow BIOS copy will be returned instead of the
 112 * actual ROM.
 113 */
 114void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
 115{
 116        struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 117        loff_t start;
 118        void __iomem *rom;
 119
 120        /*
 121         * IORESOURCE_ROM_SHADOW set on x86, x86_64 and IA64 supports legacy
 122         * memory map if the VGA enable bit of the Bridge Control register is
 123         * set for embedded VGA.
 124         */
 125        if (res->flags & IORESOURCE_ROM_SHADOW) {
 126                /* primary video rom always starts here */
 127                start = (loff_t)0xC0000;
 128                *size = 0x20000; /* cover C000:0 through E000:0 */
 129        } else {
 130                if (res->flags &
 131                        (IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY)) {
 132                        *size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
 133                        return (void __iomem *)(unsigned long)
 134                                pci_resource_start(pdev, PCI_ROM_RESOURCE);
 135                } else {
 136                        /* assign the ROM an address if it doesn't have one */
 137                        if (res->parent == NULL &&
 138                            pci_assign_resource(pdev,PCI_ROM_RESOURCE))
 139                                return NULL;
 140                        start = pci_resource_start(pdev, PCI_ROM_RESOURCE);
 141                        *size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
 142                        if (*size == 0)
 143                                return NULL;
 144
 145                        /* Enable ROM space decodes */
 146                        if (pci_enable_rom(pdev))
 147                                return NULL;
 148                }
 149        }
 150
 151        rom = ioremap(start, *size);
 152        if (!rom) {
 153                /* restore enable if ioremap fails */
 154                if (!(res->flags & (IORESOURCE_ROM_ENABLE |
 155                                    IORESOURCE_ROM_SHADOW |
 156                                    IORESOURCE_ROM_COPY)))
 157                        pci_disable_rom(pdev);
 158                return NULL;
 159        }
 160
 161        /*
 162         * Try to find the true size of the ROM since sometimes the PCI window
 163         * size is much larger than the actual size of the ROM.
 164         * True size is important if the ROM is going to be copied.
 165         */
 166        *size = pci_get_rom_size(pdev, rom, *size);
 167        return rom;
 168}
 169
 170/**
 171 * pci_unmap_rom - unmap the ROM from kernel space
 172 * @pdev: pointer to pci device struct
 173 * @rom: virtual address of the previous mapping
 174 *
 175 * Remove a mapping of a previously mapped ROM
 176 */
 177void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
 178{
 179        struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 180
 181        if (res->flags & (IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY))
 182                return;
 183
 184        iounmap(rom);
 185
 186        /* Disable again before continuing, leave enabled if pci=rom */
 187        if (!(res->flags & (IORESOURCE_ROM_ENABLE | IORESOURCE_ROM_SHADOW)))
 188                pci_disable_rom(pdev);
 189}
 190
 191/**
 192 * pci_cleanup_rom - free the ROM copy created by pci_map_rom_copy
 193 * @pdev: pointer to pci device struct
 194 *
 195 * Free the copied ROM if we allocated one.
 196 */
 197void pci_cleanup_rom(struct pci_dev *pdev)
 198{
 199        struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 200        if (res->flags & IORESOURCE_ROM_COPY) {
 201                kfree((void*)(unsigned long)res->start);
 202                res->flags &= ~IORESOURCE_ROM_COPY;
 203                res->start = 0;
 204                res->end = 0;
 205        }
 206}
 207
 208/**
 209 * pci_platform_rom - provides a pointer to any ROM image provided by the
 210 * platform
 211 * @pdev: pointer to pci device struct
 212 * @size: pointer to receive size of pci window over ROM
 213 */
 214void __iomem *pci_platform_rom(struct pci_dev *pdev, size_t *size)
 215{
 216        if (pdev->rom && pdev->romlen) {
 217                *size = pdev->romlen;
 218                return phys_to_virt((phys_addr_t)pdev->rom);
 219        }
 220
 221        return NULL;
 222}
 223
 224EXPORT_SYMBOL(pci_map_rom);
 225EXPORT_SYMBOL(pci_unmap_rom);
 226EXPORT_SYMBOL_GPL(pci_enable_rom);
 227EXPORT_SYMBOL_GPL(pci_disable_rom);
 228EXPORT_SYMBOL(pci_platform_rom);
 229
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