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 size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size) 84 { 85 void __iomem *image; 86 int last_image; 87 unsigned length; 88 89 image = rom; 90 do { 91 void __iomem *pds; 92 /* Standard PCI ROMs start out with these bytes 55 AA */ 93 if (readw(image) != 0xAA55) { 94 pci_info(pdev, "Invalid PCI ROM header signature: expecting 0xaa55, got %#06x\n", 95 readw(image)); 96 break; 97 } 98 /* get the PCI data structure and check its "PCIR" signature */ 99 pds = image + readw(image + 24); 100 if (readl(pds) != 0x52494350) { 101 pci_info(pdev, "Invalid PCI ROM data signature: expecting 0x52494350, got %#010x\n", 102 readl(pds)); 103 break; 104 } 105 last_image = readb(pds + 21) & 0x80; 106 length = readw(pds + 16); 107 image += length * 512; 108 /* Avoid iterating through memory outside the resource window */ 109 if (image > rom + size) 110 break; 111 } while (length && !last_image); 112 113 /* never return a size larger than the PCI resource window */ 114 /* there are known ROMs that get the size wrong */ 115 return min((size_t)(image - rom), size); 116 } 117 118 /** 119 * pci_map_rom - map a PCI ROM to kernel space 120 * @pdev: pointer to pci device struct 121 * @size: pointer to receive size of pci window over ROM 122 * 123 * Return: kernel virtual pointer to image of ROM 124 * 125 * Map a PCI ROM into kernel space. If ROM is boot video ROM, 126 * the shadow BIOS copy will be returned instead of the 127 * actual ROM. 128 */ 129 void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size) 130 { 131 struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; 132 loff_t start; 133 void __iomem *rom; 134 135 /* assign the ROM an address if it doesn't have one */ 136 if (res->parent == NULL && pci_assign_resource(pdev, PCI_ROM_RESOURCE)) 137 return NULL; 138 139 start = pci_resource_start(pdev, PCI_ROM_RESOURCE); 140 *size = pci_resource_len(pdev, PCI_ROM_RESOURCE); 141 if (*size == 0) 142 return NULL; 143 144 /* Enable ROM space decodes */ 145 if (pci_enable_rom(pdev)) 146 return NULL; 147 148 rom = ioremap(start, *size); 149 if (!rom) 150 goto err_ioremap; 151 152 /* 153 * Try to find the true size of the ROM since sometimes the PCI window 154 * size is much larger than the actual size of the ROM. 155 * True size is important if the ROM is going to be copied. 156 */ 157 *size = pci_get_rom_size(pdev, rom, *size); 158 if (!*size) 159 goto invalid_rom; 160 161 return rom; 162 163 invalid_rom: 164 iounmap(rom); 165 err_ioremap: 166 /* restore enable if ioremap fails */ 167 if (!(res->flags & IORESOURCE_ROM_ENABLE)) 168 pci_disable_rom(pdev); 169 return NULL; 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 iounmap(rom); 185 186 /* Disable again before continuing */ 187 if (!(res->flags & IORESOURCE_ROM_ENABLE)) 188 pci_disable_rom(pdev); 189 } 190 EXPORT_SYMBOL(pci_unmap_rom); 191 192 /** 193 * pci_platform_rom - provides a pointer to any ROM image provided by the 194 * platform 195 * @pdev: pointer to pci device struct 196 * @size: pointer to receive size of pci window over ROM 197 */ 198 void __iomem *pci_platform_rom(struct pci_dev *pdev, size_t *size) 199 { 200 if (pdev->rom && pdev->romlen) { 201 *size = pdev->romlen; 202 return phys_to_virt((phys_addr_t)pdev->rom); 203 } 204 205 return NULL; 206 } 207 EXPORT_SYMBOL(pci_platform_rom); 208