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  */
  25 int 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 }
  50 EXPORT_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  */
  59 void 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 }
  71 EXPORT_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  */
  84 size_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  */
 130 void __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 }
 165 EXPORT_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  */
 174 void 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 }
 184 EXPORT_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  */
 192 void __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 }
 201 EXPORT_SYMBOL(pci_platform_rom);