LXR linux/drivers/pci/rom.c

   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        /* Nothing to enable if we're using a shadow copy in RAM */
  35        if (res->flags & IORESOURCE_ROM_SHADOW)
  36                return 0;
  37
  38        /*
  39         * Ideally pci_update_resource() would update the ROM BAR address,
  40         * and we would only set the enable bit here.  But apparently some
  41         * devices have buggy ROM BARs that read as zero when disabled.
  42         */
  43        pcibios_resource_to_bus(pdev->bus, &region, res);
  44        pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
  45        rom_addr &= ~PCI_ROM_ADDRESS_MASK;
  46        rom_addr |= region.start | PCI_ROM_ADDRESS_ENABLE;
  47        pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
  48        return 0;
  49}
  50EXPORT_SYMBOL_GPL(pci_enable_rom);
  51
  52/**
  53 * pci_disable_rom - disable ROM decoding for a PCI device
  54 * @pdev: PCI device to disable
  55 *
  56 * Disable ROM decoding on a PCI device by turning off the last bit in the
  57 * ROM BAR.
  58 */
  59void pci_disable_rom(struct pci_dev *pdev)
  60{
  61        struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
  62        u32 rom_addr;
  63
  64        if (res->flags & IORESOURCE_ROM_SHADOW)
  65                return;
  66
  67        pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr);
  68        rom_addr &= ~PCI_ROM_ADDRESS_ENABLE;
  69        pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr);
  70}
  71EXPORT_SYMBOL_GPL(pci_disable_rom);
  72
  73/**
  74 * pci_get_rom_size - obtain the actual size of the ROM image
  75 * @pdev: target PCI device
  76 * @rom: kernel virtual pointer to image of ROM
  77 * @size: size of PCI window
  78 *  return: size of actual ROM image
  79 *
  80 * Determine the actual length of the ROM image.
  81 * The PCI window size could be much larger than the
  82 * actual image size.
  83 */
  84size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, 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                        dev_err(&pdev->dev, "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                        dev_err(&pdev->dev, "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        } while (length && !last_image);
 113
 114        /* never return a size larger than the PCI resource window */
 115        /* there are known ROMs that get the size wrong */
 116        return min((size_t)(image - rom), size);
 117}
 118
 119/**
 120 * pci_map_rom - map a PCI ROM to kernel space
 121 * @pdev: pointer to pci device struct
 122 * @size: pointer to receive size of pci window over ROM
 123 *
 124 * Return: kernel virtual pointer to image of ROM
 125 *
 126 * Map a PCI ROM into kernel space. If ROM is boot video ROM,
 127 * the shadow BIOS copy will be returned instead of the
 128 * actual ROM.
 129 */
 130void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
 131{
 132        struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 133        loff_t start;
 134        void __iomem *rom;
 135
 136        /* assign the ROM an address if it doesn't have one */
 137        if (res->parent == NULL && pci_assign_resource(pdev, PCI_ROM_RESOURCE))
 138                return NULL;
 139
 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        rom = ioremap(start, *size);
 150        if (!rom) {
 151                /* restore enable if ioremap fails */
 152                if (!(res->flags & IORESOURCE_ROM_ENABLE))
 153                        pci_disable_rom(pdev);
 154                return NULL;
 155        }
 156
 157        /*
 158         * Try to find the true size of the ROM since sometimes the PCI window
 159         * size is much larger than the actual size of the ROM.
 160         * True size is important if the ROM is going to be copied.
 161         */
 162        *size = pci_get_rom_size(pdev, rom, *size);
 163        return rom;
 164}
 165EXPORT_SYMBOL(pci_map_rom);
 166
 167/**
 168 * pci_unmap_rom - unmap the ROM from kernel space
 169 * @pdev: pointer to pci device struct
 170 * @rom: virtual address of the previous mapping
 171 *
 172 * Remove a mapping of a previously mapped ROM
 173 */
 174void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
 175{
 176        struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 177
 178        iounmap(rom);
 179
 180        /* Disable again before continuing */
 181        if (!(res->flags & IORESOURCE_ROM_ENABLE))
 182                pci_disable_rom(pdev);
 183}
 184EXPORT_SYMBOL(pci_unmap_rom);
 185
 186/**
 187 * pci_platform_rom - provides a pointer to any ROM image provided by the
 188 * platform
 189 * @pdev: pointer to pci device struct
 190 * @size: pointer to receive size of pci window over ROM
 191 */
 192void __iomem *pci_platform_rom(struct pci_dev *pdev, size_t *size)
 193{
 194        if (pdev->rom && pdev->romlen) {
 195                *size = pdev->romlen;
 196                return phys_to_virt((phys_addr_t)pdev->rom);
 197        }
 198
 199        return NULL;
 200}
 201EXPORT_SYMBOL(pci_platform_rom);
 202