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