linux/arch/x86/kernel/early-quirks.c

/* Various workarounds for chipset bugs.
   This code runs very early and can't use the regular PCI subsystem
   The entries are keyed to PCI bridges which usually identify chipsets
   uniquely.
   This is only for whole classes of chipsets with specific problems which
   need early invasive action (e.g. before the timers are initialized).
   Most PCI device specific workarounds can be done later and should be
   in standard PCI quirks
   Mainboard specific bugs should be handled by DMI entries.
   CPU specific bugs in setup.c */

#include <linux/pci.h>
#include <linux/acpi.h>
#include <linux/delay.h>
#include <linux/dmi.h>
#include <linux/pci_ids.h>
#include <linux/bcma/bcma.h>
#include <linux/bcma/bcma_regs.h>
#include <drm/i915_drm.h>
#include <asm/pci-direct.h>
#include <asm/dma.h>
#include <asm/io_apic.h>
#include <asm/apic.h>
#include <asm/hpet.h>
#include <asm/iommu.h>
#include <asm/gart.h>
#include <asm/irq_remapping.h>
#include <asm/early_ioremap.h>

#define dev_err(msg)  pr_err("pci 0000:%02x:%02x.%d: %s", bus, slot, func, msg)

static void __init fix_hypertransport_config(int num, int slot, int func)
{
	u32 htcfg;
	/*
	 * we found a hypertransport bus
	 * make sure that we are broadcasting
	 * interrupts to all cpus on the ht bus
	 * if we're using extended apic ids
	 */
	htcfg = read_pci_config(num, slot, func, 0x68);
	if (htcfg & (1 << 18)) {
		printk(KERN_INFO "Detected use of extended apic ids "
				 "on hypertransport bus\n");
		if ((htcfg & (1 << 17)) == 0) {
			printk(KERN_INFO "Enabling hypertransport extended "
					 "apic interrupt broadcast\n");
			printk(KERN_INFO "Note this is a bios bug, "
					 "please contact your hw vendor\n");
			htcfg |= (1 << 17);
			write_pci_config(num, slot, func, 0x68, htcfg);
		}
	}


}

static void __init via_bugs(int  num, int slot, int func)
{
#ifdef CONFIG_GART_IOMMU
	if ((max_pfn > MAX_DMA32_PFN ||  force_iommu) &&
	    !gart_iommu_aperture_allowed) {
		printk(KERN_INFO
		       "Looks like a VIA chipset. Disabling IOMMU."
		       " Override with iommu=allowed\n");
		gart_iommu_aperture_disabled = 1;
	}
#endif
}

#ifdef CONFIG_ACPI
#ifdef CONFIG_X86_IO_APIC

static int __init nvidia_hpet_check(struct acpi_table_header *header)
{
	return 0;
}
#endif /* CONFIG_X86_IO_APIC */
#endif /* CONFIG_ACPI */

static void __init nvidia_bugs(int num, int slot, int func)
{
#ifdef CONFIG_ACPI
#ifdef CONFIG_X86_IO_APIC
	/*
	 * Only applies to Nvidia root ports (bus 0) and not to
	 * Nvidia graphics cards with PCI ports on secondary buses.
	 */
	if (num)
		return;

	/*
	 * All timer overrides on Nvidia are
	 * wrong unless HPET is enabled.
	 * Unfortunately that's not true on many Asus boards.
	 * We don't know yet how to detect this automatically, but
	 * at least allow a command line override.
	 */
	if (acpi_use_timer_override)
		return;

	if (acpi_table_parse(ACPI_SIG_HPET, nvidia_hpet_check)) {
		acpi_skip_timer_override = 1;
		printk(KERN_INFO "Nvidia board "
		       "detected. Ignoring ACPI "
		       "timer override.\n");
		printk(KERN_INFO "If you got timer trouble "
			"try acpi_use_timer_override\n");
	}
#endif
#endif
	/* RED-PEN skip them on mptables too? */

}

#if defined(CONFIG_ACPI) && defined(CONFIG_X86_IO_APIC)
static u32 __init ati_ixp4x0_rev(int num, int slot, int func)
{
	u32 d;
	u8  b;

	b = read_pci_config_byte(num, slot, func, 0xac);
	b &= ~(1<<5);
	write_pci_config_byte(num, slot, func, 0xac, b);

	d = read_pci_config(num, slot, func, 0x70);
	d |= 1<<8;
	write_pci_config(num, slot, func, 0x70, d);

	d = read_pci_config(num, slot, func, 0x8);
	d &= 0xff;
	return d;
}

static void __init ati_bugs(int num, int slot, int func)
{
	u32 d;
	u8  b;

	if (acpi_use_timer_override)
		return;

	d = ati_ixp4x0_rev(num, slot, func);
	if (d  < 0x82)
		acpi_skip_timer_override = 1;
	else {
		/* check for IRQ0 interrupt swap */
		outb(0x72, 0xcd6); b = inb(0xcd7);
		if (!(b & 0x2))
			acpi_skip_timer_override = 1;
	}

	if (acpi_skip_timer_override) {
		printk(KERN_INFO "SB4X0 revision 0x%x\n", d);
		printk(KERN_INFO "Ignoring ACPI timer override.\n");
		printk(KERN_INFO "If you got timer trouble "
		       "try acpi_use_timer_override\n");
	}
}

static u32 __init ati_sbx00_rev(int num, int slot, int func)
{
	u32 d;

	d = read_pci_config(num, slot, func, 0x8);
	d &= 0xff;

	return d;
}

static void __init ati_bugs_contd(int num, int slot, int func)
{
	u32 d, rev;

	rev = ati_sbx00_rev(num, slot, func);
	if (rev >= 0x40)
		acpi_fix_pin2_polarity = 1;

	/*
	 * SB600: revisions 0x11, 0x12, 0x13, 0x14, ...
	 * SB700: revisions 0x39, 0x3a, ...
	 * SB800: revisions 0x40, 0x41, ...
	 */
	if (rev >= 0x39)
		return;

	if (acpi_use_timer_override)
		return;

	/* check for IRQ0 interrupt swap */
	d = read_pci_config(num, slot, func, 0x64);
	if (!(d & (1<<14)))
		acpi_skip_timer_override = 1;

	if (acpi_skip_timer_override) {
		printk(KERN_INFO "SB600 revision 0x%x\n", rev);
		printk(KERN_INFO "Ignoring ACPI timer override.\n");
		printk(KERN_INFO "If you got timer trouble "
		       "try acpi_use_timer_override\n");
	}
}
#else
static void __init ati_bugs(int num, int slot, int func)
{
}

static void __init ati_bugs_contd(int num, int slot, int func)
{
}
#endif

static void __init intel_remapping_check(int num, int slot, int func)
{
	u8 revision;
	u16 device;

	device = read_pci_config_16(num, slot, func, PCI_DEVICE_ID);
	revision = read_pci_config_byte(num, slot, func, PCI_REVISION_ID);

	/*
	 * Revision <= 13 of all triggering devices id in this quirk
	 * have a problem draining interrupts when irq remapping is
	 * enabled, and should be flagged as broken. Additionally
	 * revision 0x22 of device id 0x3405 has this problem.
	 */
	if (revision <= 0x13)
		set_irq_remapping_broken();
	else if (device == 0x3405 && revision == 0x22)
		set_irq_remapping_broken();
}

/*
 * Systems with Intel graphics controllers set aside memory exclusively
 * for gfx driver use.  This memory is not marked in the E820 as reserved
 * or as RAM, and so is subject to overlap from E820 manipulation later
 * in the boot process.  On some systems, MMIO space is allocated on top,
 * despite the efforts of the "RAM buffer" approach, which simply rounds
 * memory boundaries up to 64M to try to catch space that may decode
 * as RAM and so is not suitable for MMIO.
 */

#define KB(x)	((x) * 1024UL)
#define MB(x)	(KB (KB (x)))

static size_t __init i830_tseg_size(void)
{
	u8 esmramc = read_pci_config_byte(0, 0, 0, I830_ESMRAMC);

	if (!(esmramc & TSEG_ENABLE))
		return 0;

	if (esmramc & I830_TSEG_SIZE_1M)
		return MB(1);
	else
		return KB(512);
}

static size_t __init i845_tseg_size(void)
{
	u8 esmramc = read_pci_config_byte(0, 0, 0, I845_ESMRAMC);
	u8 tseg_size = esmramc & I845_TSEG_SIZE_MASK;

	if (!(esmramc & TSEG_ENABLE))
		return 0;

	switch (tseg_size) {
	case I845_TSEG_SIZE_512K:	return KB(512);
	case I845_TSEG_SIZE_1M:		return MB(1);
	default:
		WARN(1, "Unknown ESMRAMC value: %x!\n", esmramc);
	}
	return 0;
}

static size_t __init i85x_tseg_size(void)
{
	u8 esmramc = read_pci_config_byte(0, 0, 0, I85X_ESMRAMC);

	if (!(esmramc & TSEG_ENABLE))
		return 0;

	return MB(1);
}

static size_t __init i830_mem_size(void)
{
	return read_pci_config_byte(0, 0, 0, I830_DRB3) * MB(32);
}

static size_t __init i85x_mem_size(void)
{
	return read_pci_config_byte(0, 0, 1, I85X_DRB3) * MB(32);
}

/*
 * On 830/845/85x the stolen memory base isn't available in any
 * register. We need to calculate it as TOM-TSEG_SIZE-stolen_size.
 */
static phys_addr_t __init i830_stolen_base(int num, int slot, int func,
					   size_t stolen_size)
{
	return (phys_addr_t)i830_mem_size() - i830_tseg_size() - stolen_size;
}

static phys_addr_t __init i845_stolen_base(int num, int slot, int func,
					   size_t stolen_size)
{
	return (phys_addr_t)i830_mem_size() - i845_tseg_size() - stolen_size;
}

static phys_addr_t __init i85x_stolen_base(int num, int slot, int func,
					   size_t stolen_size)
{
	return (phys_addr_t)i85x_mem_size() - i85x_tseg_size() - stolen_size;
}

static phys_addr_t __init i865_stolen_base(int num, int slot, int func,
					   size_t stolen_size)
{
	u16 toud = 0;

	toud = read_pci_config_16(0, 0, 0, I865_TOUD);

	return (phys_addr_t)(toud << 16) + i845_tseg_size();
}

static phys_addr_t __init gen3_stolen_base(int num, int slot, int func,
					   size_t stolen_size)
{
	u32 bsm;

	/* Almost universally we can find the Graphics Base of Stolen Memory
	 * at register BSM (0x5c) in the igfx configuration space. On a few
	 * (desktop) machines this is also mirrored in the bridge device at
	 * different locations, or in the MCHBAR.
	 */
	bsm = read_pci_config(num, slot, func, INTEL_BSM);

	return (phys_addr_t)bsm & INTEL_BSM_MASK;
}

static size_t __init i830_stolen_size(int num, int slot, int func)
{
	u16 gmch_ctrl;
	u16 gms;

	gmch_ctrl = read_pci_config_16(0, 0, 0, I830_GMCH_CTRL);
	gms = gmch_ctrl & I830_GMCH_GMS_MASK;

	switch (gms) {
	case I830_GMCH_GMS_STOLEN_512:	return KB(512);
	case I830_GMCH_GMS_STOLEN_1024:	return MB(1);
	case I830_GMCH_GMS_STOLEN_8192:	return MB(8);
	/* local memory isn't part of the normal address space */
	case I830_GMCH_GMS_LOCAL:	return 0;
	default:
		WARN(1, "Unknown GMCH_CTRL value: %x!\n", gmch_ctrl);
	}

	return 0;
}

static size_t __init gen3_stolen_size(int num, int slot, int func)
{
	u16 gmch_ctrl;
	u16 gms;

	gmch_ctrl = read_pci_config_16(0, 0, 0, I830_GMCH_CTRL);
	gms = gmch_ctrl & I855_GMCH_GMS_MASK;

	switch (gms) {
	case I855_GMCH_GMS_STOLEN_1M:	return MB(1);
	case I855_GMCH_GMS_STOLEN_4M:	return MB(4);
	case I855_GMCH_GMS_STOLEN_8M:	return MB(8);
	case I855_GMCH_GMS_STOLEN_16M:	return MB(16);
	case I855_GMCH_GMS_STOLEN_32M:	return MB(32);
	case I915_GMCH_GMS_STOLEN_48M:	return MB(48);
	case I915_GMCH_GMS_STOLEN_64M:	return MB(64);
	case G33_GMCH_GMS_STOLEN_128M:	return MB(128);
	case G33_GMCH_GMS_STOLEN_256M:	return MB(256);
	case INTEL_GMCH_GMS_STOLEN_96M:	return MB(96);
	case INTEL_GMCH_GMS_STOLEN_160M:return MB(160);
	case INTEL_GMCH_GMS_STOLEN_224M:return MB(224);
	case INTEL_GMCH_GMS_STOLEN_352M:return MB(352);
	default:
		WARN(1, "Unknown GMCH_CTRL value: %x!\n", gmch_ctrl);
	}

	return 0;
}

static size_t __init gen6_stolen_size(int num, int slot, int func)
{
	u16 gmch_ctrl;
	u16 gms;

	gmch_ctrl = read_pci_config_16(num, slot, func, SNB_GMCH_CTRL);
	gms = (gmch_ctrl >> SNB_GMCH_GMS_SHIFT) & SNB_GMCH_GMS_MASK;

	return (size_t)gms * MB(32);
}

static size_t __init gen8_stolen_size(int num, int slot, int func)
{
	u16 gmch_ctrl;
	u16 gms;

	gmch_ctrl = read_pci_config_16(num, slot, func, SNB_GMCH_CTRL);
	gms = (gmch_ctrl >> BDW_GMCH_GMS_SHIFT) & BDW_GMCH_GMS_MASK;

	return (size_t)gms * MB(32);
}

static size_t __init chv_stolen_size(int num, int slot, int func)
{
	u16 gmch_ctrl;
	u16 gms;

	gmch_ctrl = read_pci_config_16(num, slot, func, SNB_GMCH_CTRL);
	gms = (gmch_ctrl >> SNB_GMCH_GMS_SHIFT) & SNB_GMCH_GMS_MASK;

	/*
	 * 0x0  to 0x10: 32MB increments starting at 0MB
	 * 0x11 to 0x16: 4MB increments starting at 8MB
	 * 0x17 to 0x1d: 4MB increments start at 36MB
	 */
	if (gms < 0x11)
		return (size_t)gms * MB(32);
	else if (gms < 0x17)
		return (size_t)(gms - 0x11 + 2) * MB(4);
	else
		return (size_t)(gms - 0x17 + 9) * MB(4);
}

static size_t __init gen9_stolen_size(int num, int slot, int func)
{
	u16 gmch_ctrl;
	u16 gms;

	gmch_ctrl = read_pci_config_16(num, slot, func, SNB_GMCH_CTRL);
	gms = (gmch_ctrl >> BDW_GMCH_GMS_SHIFT) & BDW_GMCH_GMS_MASK;

	/* 0x0  to 0xef: 32MB increments starting at 0MB */
	/* 0xf0 to 0xfe: 4MB increments starting at 4MB */
	if (gms < 0xf0)
		return (size_t)gms * MB(32);
	else
		return (size_t)(gms - 0xf0 + 1) * MB(4);
}

struct intel_early_ops {
	size_t (*stolen_size)(int num, int slot, int func);
	phys_addr_t (*stolen_base)(int num, int slot, int func, size_t size);
};

static const struct intel_early_ops i830_early_ops __initconst = {
	.stolen_base = i830_stolen_base,
	.stolen_size = i830_stolen_size,
};

static const struct intel_early_ops i845_early_ops __initconst = {
	.stolen_base = i845_stolen_base,
	.stolen_size = i830_stolen_size,
};

static const struct intel_early_ops i85x_early_ops __initconst = {
	.stolen_base = i85x_stolen_base,
	.stolen_size = gen3_stolen_size,
};

static const struct intel_early_ops i865_early_ops __initconst = {
	.stolen_base = i865_stolen_base,
	.stolen_size = gen3_stolen_size,
};

static const struct intel_early_ops gen3_early_ops __initconst = {
	.stolen_base = gen3_stolen_base,
	.stolen_size = gen3_stolen_size,
};

static const struct intel_early_ops gen6_early_ops __initconst = {
	.stolen_base = gen3_stolen_base,
	.stolen_size = gen6_stolen_size,
};

static const struct intel_early_ops gen8_early_ops __initconst = {
	.stolen_base = gen3_stolen_base,
	.stolen_size = gen8_stolen_size,
};

static const struct intel_early_ops gen9_early_ops __initconst = {
	.stolen_base = gen3_stolen_base,
	.stolen_size = gen9_stolen_size,
};

static const struct intel_early_ops chv_early_ops __initconst = {
	.stolen_base = gen3_stolen_base,
	.stolen_size = chv_stolen_size,
};

static const struct pci_device_id intel_early_ids[] __initconst = {
	INTEL_I830_IDS(&i830_early_ops),
	INTEL_I845G_IDS(&i845_early_ops),
	INTEL_I85X_IDS(&i85x_early_ops),
	INTEL_I865G_IDS(&i865_early_ops),
	INTEL_I915G_IDS(&gen3_early_ops),
	INTEL_I915GM_IDS(&gen3_early_ops),
	INTEL_I945G_IDS(&gen3_early_ops),
	INTEL_I945GM_IDS(&gen3_early_ops),
	INTEL_VLV_IDS(&gen6_early_ops),
	INTEL_PINEVIEW_IDS(&gen3_early_ops),
	INTEL_I965G_IDS(&gen3_early_ops),
	INTEL_G33_IDS(&gen3_early_ops),
	INTEL_I965GM_IDS(&gen3_early_ops),
	INTEL_GM45_IDS(&gen3_early_ops),
	INTEL_G45_IDS(&gen3_early_ops),
	INTEL_IRONLAKE_D_IDS(&gen3_early_ops),
	INTEL_IRONLAKE_M_IDS(&gen3_early_ops),
	INTEL_SNB_D_IDS(&gen6_early_ops),
	INTEL_SNB_M_IDS(&gen6_early_ops),
	INTEL_IVB_M_IDS(&gen6_early_ops),
	INTEL_IVB_D_IDS(&gen6_early_ops),
	INTEL_HSW_IDS(&gen6_early_ops),
	INTEL_BDW_IDS(&gen8_early_ops),
	INTEL_CHV_IDS(&chv_early_ops),
	INTEL_SKL_IDS(&gen9_early_ops),
	INTEL_BXT_IDS(&gen9_early_ops),
	INTEL_KBL_IDS(&gen9_early_ops),
};

static void __init
intel_graphics_stolen(int num, int slot, int func,
		      const struct intel_early_ops *early_ops)
{
	phys_addr_t base, end;
	size_t size;

	size = early_ops->stolen_size(num, slot, func);
	base = early_ops->stolen_base(num, slot, func, size);

	if (!size || !base)
		return;

	end = base + size - 1;
	printk(KERN_INFO "Reserving Intel graphics memory at %pa-%pa\n",
	       &base, &end);

	/* Mark this space as reserved */
	e820__range_add(base, size, E820_RESERVED);
	e820__update_table(e820_table->entries, ARRAY_SIZE(e820_table->entries), &e820_table->nr_entries);
}

static void __init intel_graphics_quirks(int num, int slot, int func)
{
	const struct intel_early_ops *early_ops;
	u16 device;
	int i;

	device = read_pci_config_16(num, slot, func, PCI_DEVICE_ID);

	for (i = 0; i < ARRAY_SIZE(intel_early_ids); i++) {
		kernel_ulong_t driver_data = intel_early_ids[i].driver_data;

		if (intel_early_ids[i].device != device)
			continue;

		early_ops = (typeof(early_ops))driver_data;

		intel_graphics_stolen(num, slot, func, early_ops);

		return;
	}
}

static void __init force_disable_hpet(int num, int slot, int func)
{
#ifdef CONFIG_HPET_TIMER
	boot_hpet_disable = true;
	pr_info("x86/hpet: Will disable the HPET for this platform because it's not reliable\n");
#endif
}

#define BCM4331_MMIO_SIZE	16384
#define BCM4331_PM_CAP		0x40
#define bcma_aread32(reg)	ioread32(mmio + 1 * BCMA_CORE_SIZE + reg)
#define bcma_awrite32(reg, val)	iowrite32(val, mmio + 1 * BCMA_CORE_SIZE + reg)

static void __init apple_airport_reset(int bus, int slot, int func)
{
	void __iomem *mmio;
	u16 pmcsr;
	u64 addr;
	int i;

	if (!dmi_match(DMI_SYS_VENDOR, "Apple Inc."))
		return;

	/* Card may have been put into PCI_D3hot by grub quirk */
	pmcsr = read_pci_config_16(bus, slot, func, BCM4331_PM_CAP + PCI_PM_CTRL);

	if ((pmcsr & PCI_PM_CTRL_STATE_MASK) != PCI_D0) {
		pmcsr &= ~PCI_PM_CTRL_STATE_MASK;
		write_pci_config_16(bus, slot, func, BCM4331_PM_CAP + PCI_PM_CTRL, pmcsr);
		mdelay(10);

		pmcsr = read_pci_config_16(bus, slot, func, BCM4331_PM_CAP + PCI_PM_CTRL);
		if ((pmcsr & PCI_PM_CTRL_STATE_MASK) != PCI_D0) {
			dev_err("Cannot power up Apple AirPort card\n");
			return;
		}
	}

	addr  =      read_pci_config(bus, slot, func, PCI_BASE_ADDRESS_0);
	addr |= (u64)read_pci_config(bus, slot, func, PCI_BASE_ADDRESS_1) << 32;
	addr &= PCI_BASE_ADDRESS_MEM_MASK;

	mmio = early_ioremap(addr, BCM4331_MMIO_SIZE);
	if (!mmio) {
		dev_err("Cannot iomap Apple AirPort card\n");
		return;
	}

	pr_info("Resetting Apple AirPort card (left enabled by EFI)\n");

	for (i = 0; bcma_aread32(BCMA_RESET_ST) && i < 30; i++)
		udelay(10);

	bcma_awrite32(BCMA_RESET_CTL, BCMA_RESET_CTL_RESET);
	bcma_aread32(BCMA_RESET_CTL);
	udelay(1);

	bcma_awrite32(BCMA_RESET_CTL, 0);
	bcma_aread32(BCMA_RESET_CTL);
	udelay(10);

	early_iounmap(mmio, BCM4331_MMIO_SIZE);
}

#define QFLAG_APPLY_ONCE 	0x1
#define QFLAG_APPLIED		0x2
#define QFLAG_DONE		(QFLAG_APPLY_ONCE|QFLAG_APPLIED)
struct chipset {
	u32 vendor;
	u32 device;
	u32 class;
	u32 class_mask;
	u32 flags;
	void (*f)(int num, int slot, int func);
};

static struct chipset early_qrk[] __initdata = {
	{ PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID,
	  PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, nvidia_bugs },
	{ PCI_VENDOR_ID_VIA, PCI_ANY_ID,
	  PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, via_bugs },
	{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB,
	  PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, fix_hypertransport_config },
	{ PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP400_SMBUS,
	  PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs },
	{ PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS,
	  PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs_contd },
	{ PCI_VENDOR_ID_INTEL, 0x3403, PCI_CLASS_BRIDGE_HOST,
	  PCI_BASE_CLASS_BRIDGE, 0, intel_remapping_check },
	{ PCI_VENDOR_ID_INTEL, 0x3405, PCI_CLASS_BRIDGE_HOST,
	  PCI_BASE_CLASS_BRIDGE, 0, intel_remapping_check },
	{ PCI_VENDOR_ID_INTEL, 0x3406, PCI_CLASS_BRIDGE_HOST,
	  PCI_BASE_CLASS_BRIDGE, 0, intel_remapping_check },
	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, PCI_CLASS_DISPLAY_VGA, PCI_ANY_ID,
	  QFLAG_APPLY_ONCE, intel_graphics_quirks },
	/*
	 * HPET on the current version of the Baytrail platform has accuracy
	 * problems: it will halt in deep idle state - so we disable it.
	 *
	 * More details can be found in section 18.10.1.3 of the datasheet:
	 *
	 *    http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/atom-z8000-datasheet-vol-1.pdf
	 */
	{ PCI_VENDOR_ID_INTEL, 0x0f00,
		PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, force_disable_hpet},
	{ PCI_VENDOR_ID_BROADCOM, 0x4331,
	  PCI_CLASS_NETWORK_OTHER, PCI_ANY_ID, 0, apple_airport_reset},
	{}
};

static void __init early_pci_scan_bus(int bus);

/**
 * check_dev_quirk - apply early quirks to a given PCI device
 * @num: bus number
 * @slot: slot number
 * @func: PCI function
 *
 * Check the vendor & device ID against the early quirks table.
 *
 * If the device is single function, let early_pci_scan_bus() know so we don't
 * poke at this device again.
 */
static int __init check_dev_quirk(int num, int slot, int func)
{
	u16 class;
	u16 vendor;
	u16 device;
	u8 type;
	u8 sec;
	int i;

	class = read_pci_config_16(num, slot, func, PCI_CLASS_DEVICE);

	if (class == 0xffff)
		return -1; /* no class, treat as single function */

	vendor = read_pci_config_16(num, slot, func, PCI_VENDOR_ID);

	device = read_pci_config_16(num, slot, func, PCI_DEVICE_ID);

	for (i = 0; early_qrk[i].f != NULL; i++) {
		if (((early_qrk[i].vendor == PCI_ANY_ID) ||
			(early_qrk[i].vendor == vendor)) &&
			((early_qrk[i].device == PCI_ANY_ID) ||
			(early_qrk[i].device == device)) &&
			(!((early_qrk[i].class ^ class) &
			    early_qrk[i].class_mask))) {
				if ((early_qrk[i].flags &
				     QFLAG_DONE) != QFLAG_DONE)
					early_qrk[i].f(num, slot, func);
				early_qrk[i].flags |= QFLAG_APPLIED;
			}
	}

	type = read_pci_config_byte(num, slot, func,
				    PCI_HEADER_TYPE);

	if ((type & 0x7f) == PCI_HEADER_TYPE_BRIDGE) {
		sec = read_pci_config_byte(num, slot, func, PCI_SECONDARY_BUS);
		if (sec > num)
			early_pci_scan_bus(sec);
	}

	if (!(type & 0x80))
		return -1;

	return 0;
}

static void __init early_pci_scan_bus(int bus)
{
	int slot, func;

	/* Poor man's PCI discovery */
	for (slot = 0; slot < 32; slot++)
		for (func = 0; func < 8; func++) {
			/* Only probe function 0 on single fn devices */
			if (check_dev_quirk(bus, slot, func))
				break;
		}
}

void __init early_quirks(void)
{
	if (!early_pci_allowed())
		return;

	early_pci_scan_bus(0);
}