// SPDX-License-Identifier: GPL-2.0 /* * PCI ROM access routines * * (C) Copyright 2004 Jon Smirl <jonsmirl@yahoo.com> * (C) Copyright 2004 Silicon Graphics, Inc. Jesse Barnes <jbarnes@sgi.com> */ #include <linux/kernel.h> #include <linux/export.h> #include <linux/pci.h> #include <linux/slab.h> #include "pci.h" /** * pci_enable_rom - enable ROM decoding for a PCI device * @pdev: PCI device to enable * * Enable ROM decoding on @dev. This involves simply turning on the last * bit of the PCI ROM BAR. Note that some cards may share address decoders * between the ROM and other resources, so enabling it may disable access * to MMIO registers or other card memory. */ int pci_enable_rom(struct pci_dev *pdev) { struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; struct pci_bus_region region; u32 rom_addr; if (!res->flags) return -1; /* Nothing to enable if we're using a shadow copy in RAM */ if (res->flags & IORESOURCE_ROM_SHADOW) return 0; /* * Ideally pci_update_resource() would update the ROM BAR address, * and we would only set the enable bit here. But apparently some * devices have buggy ROM BARs that read as zero when disabled. */ pcibios_resource_to_bus(pdev->bus, ®ion, res); pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr); rom_addr &= ~PCI_ROM_ADDRESS_MASK; rom_addr |= region.start | PCI_ROM_ADDRESS_ENABLE; pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr); return 0; } EXPORT_SYMBOL_GPL(pci_enable_rom); /** * pci_disable_rom - disable ROM decoding for a PCI device * @pdev: PCI device to disable * * Disable ROM decoding on a PCI device by turning off the last bit in the * ROM BAR. */ void pci_disable_rom(struct pci_dev *pdev) { struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; u32 rom_addr; if (res->flags & IORESOURCE_ROM_SHADOW) return; pci_read_config_dword(pdev, pdev->rom_base_reg, &rom_addr); rom_addr &= ~PCI_ROM_ADDRESS_ENABLE; pci_write_config_dword(pdev, pdev->rom_base_reg, rom_addr); } EXPORT_SYMBOL_GPL(pci_disable_rom); /** * pci_get_rom_size - obtain the actual size of the ROM image * @pdev: target PCI device * @rom: kernel virtual pointer to image of ROM * @size: size of PCI window * return: size of actual ROM image * * Determine the actual length of the ROM image. * The PCI window size could be much larger than the * actual image size. */ static size_t pci_get_rom_size(struct pci_dev *pdev, void __iomem *rom, size_t size) { void __iomem *image; int last_image; unsigned int length; image = rom; do { void __iomem *pds; /* Standard PCI ROMs start out with these bytes 55 AA */ if (readw(image) != 0xAA55) { pci_info(pdev, "Invalid PCI ROM header signature: expecting 0xaa55, got %#06x\n", readw(image)); break; } /* get the PCI data structure and check its "PCIR" signature */ pds = image + readw(image + 24); if (readl(pds) != 0x52494350) { pci_info(pdev, "Invalid PCI ROM data signature: expecting 0x52494350, got %#010x\n", readl(pds)); break; } last_image = readb(pds + 21) & 0x80; length = readw(pds + 16); image += length * 512; /* Avoid iterating through memory outside the resource window */ if (image >= rom + size) break; if (!last_image) { if (readw(image) != 0xAA55) { pci_info(pdev, "No more image in the PCI ROM\n"); break; } } } while (length && !last_image); /* never return a size larger than the PCI resource window */ /* there are known ROMs that get the size wrong */ return min((size_t)(image - rom), size); } /** * pci_map_rom - map a PCI ROM to kernel space * @pdev: pointer to pci device struct * @size: pointer to receive size of pci window over ROM * * Return: kernel virtual pointer to image of ROM * * Map a PCI ROM into kernel space. If ROM is boot video ROM, * the shadow BIOS copy will be returned instead of the * actual ROM. */ void __iomem *pci_map_rom(struct pci_dev *pdev, size_t *size) { struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; loff_t start; void __iomem *rom; /* assign the ROM an address if it doesn't have one */ if (res->parent == NULL && pci_assign_resource(pdev, PCI_ROM_RESOURCE)) return NULL; start = pci_resource_start(pdev, PCI_ROM_RESOURCE); *size = pci_resource_len(pdev, PCI_ROM_RESOURCE); if (*size == 0) return NULL; /* Enable ROM space decodes */ if (pci_enable_rom(pdev)) return NULL; rom = ioremap(start, *size); if (!rom) goto err_ioremap; /* * Try to find the true size of the ROM since sometimes the PCI window * size is much larger than the actual size of the ROM. * True size is important if the ROM is going to be copied. */ *size = pci_get_rom_size(pdev, rom, *size); if (!*size) goto invalid_rom; return rom; invalid_rom: iounmap(rom); err_ioremap: /* restore enable if ioremap fails */ if (!(res->flags & IORESOURCE_ROM_ENABLE)) pci_disable_rom(pdev); return NULL; } EXPORT_SYMBOL(pci_map_rom); /** * pci_unmap_rom - unmap the ROM from kernel space * @pdev: pointer to pci device struct * @rom: virtual address of the previous mapping * * Remove a mapping of a previously mapped ROM */ void pci_unmap_rom(struct pci_dev *pdev, void __iomem *rom) { struct resource *res = &pdev->resource[PCI_ROM_RESOURCE]; iounmap(rom); /* Disable again before continuing */ if (!(res->flags & IORESOURCE_ROM_ENABLE)) pci_disable_rom(pdev); } EXPORT_SYMBOL(pci_unmap_rom);