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         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  */
  49 void 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  */
  68 size_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 static loff_t pci_find_rom(struct pci_dev *pdev, size_t *size)
 104 {
 105         struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 106         loff_t start;
 107
 108         /* assign the ROM an address if it doesn't have one */
 109         if (res->parent == NULL && pci_assign_resource(pdev, PCI_ROM_RESOURCE))
 110                 return 0;
 111         start = pci_resource_start(pdev, PCI_ROM_RESOURCE);
 112         *size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
 113
 114         if (*size == 0)
 115                 return 0;
 116
 117         /* Enable ROM space decodes */
 118         if (pci_enable_rom(pdev))
 119                 return 0;
 120
 121         return start;
 122 }
 123
 124 /**
 125  * pci_map_rom - map a PCI ROM to kernel space
 126  * @pdev: pointer to pci device struct
 127  * @size: pointer to receive size of pci window over ROM
 128  *
 129  * Return: kernel virtual pointer to image of ROM
 130  *
 131  * Map a PCI ROM into kernel space. If ROM is boot video ROM,
 132  * the shadow BIOS copy will be returned instead of the
 133  * actual ROM.
 134  */
 135 void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size)
 136 {
 137         struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 138         loff_t start = 0;
 139         void __iomem *rom;
 140
 141         /*
 142          * IORESOURCE_ROM_SHADOW set on x86, x86_64 and IA64 supports legacy
 143          * memory map if the VGA enable bit of the Bridge Control register is
 144          * set for embedded VGA.
 145          */
 146         if (res->flags & IORESOURCE_ROM_SHADOW) {
 147                 /* primary video rom always starts here */
 148                 start = (loff_t)0xC0000;
 149                 *size = 0x20000; /* cover C000:0 through E000:0 */
 150         } else {
 151                 if (res->flags &
 152                         (IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY)) {
 153                         *size = pci_resource_len(pdev, PCI_ROM_RESOURCE);
 154                         return (void __iomem *)(unsigned long)
 155                                 pci_resource_start(pdev, PCI_ROM_RESOURCE);
 156                 } else {
 157                         start = pci_find_rom(pdev, size);
 158                 }
 159         }
 160
 161         /*
 162          * Some devices may provide ROMs via a source other than the BAR
 163          */
 164         if (!start && pdev->rom && pdev->romlen) {
 165                 *size = pdev->romlen;
 166                 return phys_to_virt(pdev->rom);
 167         }
 168
 169         if (!start)
 170                 return NULL;
 171
 172         rom = ioremap(start, *size);
 173         if (!rom) {
 174                 /* restore enable if ioremap fails */
 175                 if (!(res->flags & (IORESOURCE_ROM_ENABLE |
 176                                     IORESOURCE_ROM_SHADOW |
 177                                     IORESOURCE_ROM_COPY)))
 178                         pci_disable_rom(pdev);
 179                 return NULL;
 180         }
 181
 182         /*
 183          * Try to find the true size of the ROM since sometimes the PCI window
 184          * size is much larger than the actual size of the ROM.
 185          * True size is important if the ROM is going to be copied.
 186          */
 187         *size = pci_get_rom_size(pdev, rom, *size);
 188         return rom;
 189 }
 190
 191 /**
 192  * pci_unmap_rom - unmap the ROM from kernel space
 193  * @pdev: pointer to pci device struct
 194  * @rom: virtual address of the previous mapping
 195  *
 196  * Remove a mapping of a previously mapped ROM
 197  */
 198 void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom)
 199 {
 200         struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 201
 202         if (res->flags & (IORESOURCE_ROM_COPY | IORESOURCE_ROM_BIOS_COPY))
 203                 return;
 204
 205         if (!pdev->rom || !pdev->romlen)
 206                 iounmap(rom);
 207
 208         /* Disable again before continuing, leave enabled if pci=rom */
 209         if (!(res->flags & (IORESOURCE_ROM_ENABLE | IORESOURCE_ROM_SHADOW)))
 210                 pci_disable_rom(pdev);
 211 }
 212
 213 /**
 214  * pci_cleanup_rom - free the ROM copy created by pci_map_rom_copy
 215  * @pdev: pointer to pci device struct
 216  *
 217  * Free the copied ROM if we allocated one.
 218  */
 219 void pci_cleanup_rom(struct pci_dev *pdev)
 220 {
 221         struct resource *res = &pdev->resource[PCI_ROM_RESOURCE];
 222         if (res->flags & IORESOURCE_ROM_COPY) {
 223                 kfree((void*)(unsigned long)res->start);
 224                 res->flags &= ~IORESOURCE_ROM_COPY;
 225                 res->start = 0;
 226                 res->end = 0;
 227         }
 228 }
 229
 230 EXPORT_SYMBOL(pci_map_rom);
 231 EXPORT_SYMBOL(pci_unmap_rom);
 232 EXPORT_SYMBOL_GPL(pci_enable_rom);
 233 EXPORT_SYMBOL_GPL(pci_disable_rom);