1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * PCI ROM access routines 4 * 5 * (C) Copyright 2004 Jon Smirl <jonsmirl@yahoo.com> 6 * (C) Copyright 2004 Silicon Graphics, Inc. Jesse Barnes <jbarnes@sgi.com> 7 */ 8 #include <linux/kernel.h> 9 #include <linux/export.h> 10 #include <linux/pci.h> 11 #include <linux/slab.h> 12 13 #include "pci.h" 14 15 /** 16 * pci_enable_rom - enable ROM decoding for a PCI device 17 * @pdev: PCI device to enable 18 * 19 * Enable ROM decoding on @dev. This involves simply turning on the last 20 * bit of the PCI ROM BAR. Note that some cards may share address decoders 21 * between the ROM and other resources, so enabling it may disable access 22 * to MMIO registers or other card memory. 23 */ 24 int pci_enable_rom(struct pci_dev *pdev) 25 { 26 struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; 27 struct pci_bus_region region; 28 u32 rom_addr; 29 30 if (!res->flags) 31 return -1; 32 33 /* Nothing to enable if we're using a shadow copy in RAM */ 34 if (res->flags & IORESOURCE_ROM_SHADOW) 35 return 0; 36 37 /* 38 * Ideally pci_update_resource() would update the ROM BAR address, 39 * and we would only set the enable bit here. But apparently some 40 * devices have buggy ROM BARs that read as zero when disabled. 41 */ 42 pcibios_resource_to_bus(pdev->bus, ®ion, res); 43 pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr); 44 rom_addr &= ~PCI_ROM_ADDRESS_MASK; 45 rom_addr |= region.start | PCI_ROM_ADDRESS_ENABLE; 46 pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr); 47 return 0; 48 } 49 EXPORT_SYMBOL_GPL(pci_enable_rom); 50 51 /** 52 * pci_disable_rom - disable ROM decoding for a PCI device 53 * @pdev: PCI device to disable 54 * 55 * Disable ROM decoding on a PCI device by turning off the last bit in the 56 * ROM BAR. 57 */ 58 void pci_disable_rom(struct pci_dev *pdev) 59 { 60 struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; 61 u32 rom_addr; 62 63 if (res->flags & IORESOURCE_ROM_SHADOW) 64 return; 65 66 pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr); 67 rom_addr &= ~PCI_ROM_ADDRESS_ENABLE; 68 pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr); 69 } 70 EXPORT_SYMBOL_GPL(pci_disable_rom); 71 72 /** 73 * pci_get_rom_size - obtain the actual size of the ROM image 74 * @pdev: target PCI device 75 * @rom: kernel virtual pointer to image of ROM 76 * @size: size of PCI window 77 * return: size of actual ROM image 78 * 79 * Determine the actual length of the ROM image. 80 * The PCI window size could be much larger than the 81 * actual image size. 82 */ 83 static size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, 84 size_t size) 85 { 86 void __iomem *image; 87 int last_image; 88 unsigned int 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 pci_info(pdev, "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 pci_info(pdev, "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 if (!last_image) { 113 if (readw(image) != 0xAA55) { 114 pci_info(pdev, "No more image in the PCI ROM\n"); 115 break; 116 } 117 } 118 } while (length && !last_image); 119 120 /* never return a size larger than the PCI resource window */ 121 /* there are known ROMs that get the size wrong */ 122 return min((size_t)(image - rom), size); 123 } 124 125 /** 126 * pci_map_rom - map a PCI ROM to kernel space 127 * @pdev: pointer to pci device struct 128 * @size: pointer to receive size of pci window over ROM 129 * 130 * Return: kernel virtual pointer to image of ROM 131 * 132 * Map a PCI ROM into kernel space. If ROM is boot video ROM, 133 * the shadow BIOS copy will be returned instead of the 134 * actual ROM. 135 */ 136 void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size) 137 { 138 struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; 139 loff_t start; 140 void __iomem *rom; 141 142 /* assign the ROM an address if it doesn't have one */ 143 if (res->parent == NULL && pci_assign_resource(pdev, PCI_ROM_RESOURCE)) 144 return NULL; 145 146 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 rom = ioremap(start, *size); 156 if (!rom) 157 goto err_ioremap; 158 159 /* 160 * Try to find the true size of the ROM since sometimes the PCI window 161 * size is much larger than the actual size of the ROM. 162 * True size is important if the ROM is going to be copied. 163 */ 164 *size = pci_get_rom_size(pdev, rom, *size); 165 if (!*size) 166 goto invalid_rom; 167 168 return rom; 169 170 invalid_rom: 171 iounmap(rom); 172 err_ioremap: 173 /* restore enable if ioremap fails */ 174 if (!(res->flags & IORESOURCE_ROM_ENABLE)) 175 pci_disable_rom(pdev); 176 return NULL; 177 } 178 EXPORT_SYMBOL(pci_map_rom); 179 180 /** 181 * pci_unmap_rom - unmap the ROM from kernel space 182 * @pdev: pointer to pci device struct 183 * @rom: virtual address of the previous mapping 184 * 185 * Remove a mapping of a previously mapped ROM 186 */ 187 void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom) 188 { 189 struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; 190 191 iounmap(rom); 192 193 /* Disable again before continuing */ 194 if (!(res->flags & IORESOURCE_ROM_ENABLE)) 195 pci_disable_rom(pdev); 196 } 197 EXPORT_SYMBOL(pci_unmap_rom); 198