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diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
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+/*
+ * Low-Level PCI Access for i386 machines
+ *
+ * Copyright 1993, 1994 Drew Eckhardt
+ * Visionary Computing
+ * (Unix and Linux consulting and custom programming)
+ * Drew@Colorado.EDU
+ * +1 (303) 786-7975
+ *
+ * Drew's work was sponsored by:
+ * iX Multiuser Multitasking Magazine
+ * Hannover, Germany
+ * hm@ix.de
+ *
+ * Copyright 1997--2000 Martin Mares <mj@ucw.cz>
+ *
+ * For more information, please consult the following manuals (look at
+ * http://www.pcisig.com/ for how to get them):
+ *
+ * PCI BIOS Specification
+ * PCI Local Bus Specification
+ * PCI to PCI Bridge Specification
+ * PCI System Design Guide
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/errno.h>
+
+#include "pci.h"
+
+/*
+ * We need to avoid collisions with `mirrored' VGA ports
+ * and other strange ISA hardware, so we always want the
+ * addresses to be allocated in the 0x000-0x0ff region
+ * modulo 0x400.
+ *
+ * Why? Because some silly external IO cards only decode
+ * the low 10 bits of the IO address. The 0x00-0xff region
+ * is reserved for motherboard devices that decode all 16
+ * bits, so it's ok to allocate at, say, 0x2800-0x28ff,
+ * but we want to try to avoid allocating at 0x2900-0x2bff
+ * which might have be mirrored at 0x0100-0x03ff..
+ */
+void
+pcibios_align_resource(void *data, struct resource *res,
+ resource_size_t size, resource_size_t align)
+{
+ if (res->flags & IORESOURCE_IO) {
+ resource_size_t start = res->start;
+
+ if (start & 0x300) {
+ start = (start + 0x3ff) & ~0x3ff;
+ res->start = start;
+ }
+ }
+}
+
+
+/*
+ * Handle resources of PCI devices. If the world were perfect, we could
+ * just allocate all the resource regions and do nothing more. It isn't.
+ * On the other hand, we cannot just re-allocate all devices, as it would
+ * require us to know lots of host bridge internals. So we attempt to
+ * keep as much of the original configuration as possible, but tweak it
+ * when it's found to be wrong.
+ *
+ * Known BIOS problems we have to work around:
+ * - I/O or memory regions not configured
+ * - regions configured, but not enabled in the command register
+ * - bogus I/O addresses above 64K used
+ * - expansion ROMs left enabled (this may sound harmless, but given
+ * the fact the PCI specs explicitly allow address decoders to be
+ * shared between expansion ROMs and other resource regions, it's
+ * at least dangerous)
+ *
+ * Our solution:
+ * (1) Allocate resources for all buses behind PCI-to-PCI bridges.
+ * This gives us fixed barriers on where we can allocate.
+ * (2) Allocate resources for all enabled devices. If there is
+ * a collision, just mark the resource as unallocated. Also
+ * disable expansion ROMs during this step.
+ * (3) Try to allocate resources for disabled devices. If the
+ * resources were assigned correctly, everything goes well,
+ * if they weren't, they won't disturb allocation of other
+ * resources.
+ * (4) Assign new addresses to resources which were either
+ * not configured at all or misconfigured. If explicitly
+ * requested by the user, configure expansion ROM address
+ * as well.
+ */
+
+static void __init pcibios_allocate_bus_resources(struct list_head *bus_list)
+{
+ struct pci_bus *bus;
+ struct pci_dev *dev;
+ int idx;
+ struct resource *r, *pr;
+
+ /* Depth-First Search on bus tree */
+ list_for_each_entry(bus, bus_list, node) {
+ if ((dev = bus->self)) {
+ for (idx = PCI_BRIDGE_RESOURCES;
+ idx < PCI_NUM_RESOURCES; idx++) {
+ r = &dev->resource[idx];
+ if (!r->flags)
+ continue;
+ pr = pci_find_parent_resource(dev, r);
+ if (!r->start || !pr ||
+ request_resource(pr, r) < 0) {
+ printk(KERN_ERR "PCI: Cannot allocate "
+ "resource region %d "
+ "of bridge %s\n",
+ idx, pci_name(dev));
+ /*
+ * Something is wrong with the region.
+ * Invalidate the resource to prevent
+ * child resource allocations in this
+ * range.
+ */
+ r->flags = 0;
+ }
+ }
+ }
+ pcibios_allocate_bus_resources(&bus->children);
+ }
+}
+
+static void __init pcibios_allocate_resources(int pass)
+{
+ struct pci_dev *dev = NULL;
+ int idx, disabled;
+ u16 command;
+ struct resource *r, *pr;
+
+ for_each_pci_dev(dev) {
+ pci_read_config_word(dev, PCI_COMMAND, &command);
+ for (idx = 0; idx < PCI_ROM_RESOURCE; idx++) {
+ r = &dev->resource[idx];
+ if (r->parent) /* Already allocated */
+ continue;
+ if (!r->start) /* Address not assigned at all */
+ continue;
+ if (r->flags & IORESOURCE_IO)
+ disabled = !(command & PCI_COMMAND_IO);
+ else
+ disabled = !(command & PCI_COMMAND_MEMORY);
+ if (pass == disabled) {
+ DBG("PCI: Resource %08lx-%08lx "
+ "(f=%lx, d=%d, p=%d)\n",
+ r->start, r->end, r->flags, disabled, pass);
+ pr = pci_find_parent_resource(dev, r);
+ if (!pr || request_resource(pr, r) < 0) {
+ printk(KERN_ERR "PCI: Cannot allocate "
+ "resource region %d "
+ "of device %s\n",
+ idx, pci_name(dev));
+ /* We'll assign a new address later */
+ r->end -= r->start;
+ r->start = 0;
+ }
+ }
+ }
+ if (!pass) {
+ r = &dev->resource[PCI_ROM_RESOURCE];
+ if (r->flags & IORESOURCE_ROM_ENABLE) {
+ /* Turn the ROM off, leave the resource region,
+ * but keep it unregistered. */
+ u32 reg;
+ DBG("PCI: Switching off ROM of %s\n",
+ pci_name(dev));
+ r->flags &= ~IORESOURCE_ROM_ENABLE;
+ pci_read_config_dword(dev,
+ dev->rom_base_reg, &reg);
+ pci_write_config_dword(dev, dev->rom_base_reg,
+ reg & ~PCI_ROM_ADDRESS_ENABLE);
+ }
+ }
+ }
+}
+
+static int __init pcibios_assign_resources(void)
+{
+ struct pci_dev *dev = NULL;
+ struct resource *r, *pr;
+
+ if (!(pci_probe & PCI_ASSIGN_ROMS)) {
+ /*
+ * Try to use BIOS settings for ROMs, otherwise let
+ * pci_assign_unassigned_resources() allocate the new
+ * addresses.
+ */
+ for_each_pci_dev(dev) {
+ r = &dev->resource[PCI_ROM_RESOURCE];
+ if (!r->flags || !r->start)
+ continue;
+ pr = pci_find_parent_resource(dev, r);
+ if (!pr || request_resource(pr, r) < 0) {
+ r->end -= r->start;
+ r->start = 0;
+ }
+ }
+ }
+
+ pci_assign_unassigned_resources();
+
+ return 0;
+}
+
+void __init pcibios_resource_survey(void)
+{
+ DBG("PCI: Allocating resources\n");
+ pcibios_allocate_bus_resources(&pci_root_buses);
+ pcibios_allocate_resources(0);
+ pcibios_allocate_resources(1);
+}
+
+/**
+ * called in fs_initcall (one below subsys_initcall),
+ * give a chance for motherboard reserve resources
+ */
+fs_initcall(pcibios_assign_resources);
+
+int pcibios_enable_resources(struct pci_dev *dev, int mask)
+{
+ u16 cmd, old_cmd;
+ int idx;
+ struct resource *r;
+
+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
+ old_cmd = cmd;
+ for (idx = 0; idx < PCI_NUM_RESOURCES; idx++) {
+ /* Only set up the requested stuff */
+ if (!(mask & (1 << idx)))
+ continue;
+
+ r = &dev->resource[idx];
+ if (!(r->flags & (IORESOURCE_IO | IORESOURCE_MEM)))
+ continue;
+ if ((idx == PCI_ROM_RESOURCE) &&
+ (!(r->flags & IORESOURCE_ROM_ENABLE)))
+ continue;
+ if (!r->start && r->end) {
+ printk(KERN_ERR "PCI: Device %s not available "
+ "because of resource %d collisions\n",
+ pci_name(dev), idx);
+ return -EINVAL;
+ }
+ if (r->flags & IORESOURCE_IO)
+ cmd |= PCI_COMMAND_IO;
+ if (r->flags & IORESOURCE_MEM)
+ cmd |= PCI_COMMAND_MEMORY;
+ }
+ if (cmd != old_cmd) {
+ printk("PCI: Enabling device %s (%04x -> %04x)\n",
+ pci_name(dev), old_cmd, cmd);
+ pci_write_config_word(dev, PCI_COMMAND, cmd);
+ }
+ return 0;
+}
+
+/*
+ * If we set up a device for bus mastering, we need to check the latency
+ * timer as certain crappy BIOSes forget to set it properly.
+ */
+unsigned int pcibios_max_latency = 255;
+
+void pcibios_set_master(struct pci_dev *dev)
+{
+ u8 lat;
+ pci_read_config_byte(dev, PCI_LATENCY_TIMER, &lat);
+ if (lat < 16)
+ lat = (64 <= pcibios_max_latency) ? 64 : pcibios_max_latency;
+ else if (lat > pcibios_max_latency)
+ lat = pcibios_max_latency;
+ else
+ return;
+ printk(KERN_DEBUG "PCI: Setting latency timer of device %s to %d\n",
+ pci_name(dev), lat);
+ pci_write_config_byte(dev, PCI_LATENCY_TIMER, lat);
+}
+
+int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
+ enum pci_mmap_state mmap_state, int write_combine)
+{
+ unsigned long prot;
+
+ /* I/O space cannot be accessed via normal processor loads and
+ * stores on this platform.
+ */
+ if (mmap_state == pci_mmap_io)
+ return -EINVAL;
+
+ /* Leave vm_pgoff as-is, the PCI space address is the physical
+ * address on this platform.
+ */
+ prot = pgprot_val(vma->vm_page_prot);
+ if (boot_cpu_data.x86 > 3)
+ prot |= _PAGE_PCD | _PAGE_PWT;
+ vma->vm_page_prot = __pgprot(prot);
+
+ /* Write-combine setting is ignored, it is changed via the mtrr
+ * interfaces on this platform.
+ */
+ if (io_remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
+ vma->vm_end - vma->vm_start,
+ vma->vm_page_prot))
+ return -EAGAIN;
+
+ return 0;
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.