// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* pci.c -- basic PCI support code
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*
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* (C) Copyright 2011, Greg Ungerer <gerg@uclinux.org>
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*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/init.h>
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#include <linux/pci.h>
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/*
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* From arch/i386/kernel/pci-i386.c:
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*
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* We need to avoid collisions with `mirrored' VGA ports
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* and other strange ISA hardware, so we always want the
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* addresses to be allocated in the 0x000-0x0ff region
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* modulo 0x400.
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*
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* Why? Because some silly external IO cards only decode
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* the low 10 bits of the IO address. The 0x00-0xff region
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* is reserved for motherboard devices that decode all 16
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* bits, so it's ok to allocate at, say, 0x2800-0x28ff,
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* but we want to try to avoid allocating at 0x2900-0x2bff
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* which might be mirrored at 0x0100-0x03ff..
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*/
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resource_size_t pcibios_align_resource(void *data, const struct resource *res,
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resource_size_t size, resource_size_t align)
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{
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resource_size_t start = res->start;
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if ((res->flags & IORESOURCE_IO) && (start & 0x300))
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start = (start + 0x3ff) & ~0x3ff;
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start = (start + align - 1) & ~(align - 1);
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return start;
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}
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/*
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* This is taken from the ARM code for this.
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*/
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int pcibios_enable_device(struct pci_dev *dev, int mask)
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{
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struct resource *r;
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u16 cmd, newcmd;
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int idx;
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pci_read_config_word(dev, PCI_COMMAND, &cmd);
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newcmd = cmd;
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for (idx = 0; idx < 6; idx++) {
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/* Only set up the requested stuff */
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if (!(mask & (1 << idx)))
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continue;
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r = dev->resource + idx;
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if (!r->start && r->end) {
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pr_err("PCI: Device %s not available because of resource collisions\n",
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pci_name(dev));
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return -EINVAL;
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}
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if (r->flags & IORESOURCE_IO)
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newcmd |= PCI_COMMAND_IO;
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if (r->flags & IORESOURCE_MEM)
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newcmd |= PCI_COMMAND_MEMORY;
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}
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/*
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* Bridges (eg, cardbus bridges) need to be fully enabled
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*/
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if ((dev->class >> 16) == PCI_BASE_CLASS_BRIDGE)
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newcmd |= PCI_COMMAND_IO | PCI_COMMAND_MEMORY;
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if (newcmd != cmd) {
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pr_info("PCI: enabling device %s (0x%04x -> 0x%04x)\n",
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pci_name(dev), cmd, newcmd);
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pci_write_config_word(dev, PCI_COMMAND, newcmd);
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}
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return 0;
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}
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void pcibios_fixup_bus(struct pci_bus *bus)
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{
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struct pci_dev *dev;
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list_for_each_entry(dev, &bus->devices, bus_list) {
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pci_write_config_byte(dev, PCI_CACHE_LINE_SIZE, 8);
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pci_write_config_byte(dev, PCI_LATENCY_TIMER, 32);
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}
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}
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char *pcibios_setup(char *str)
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{
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return str;
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}
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