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