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// 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 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);
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