// SPDX-License-Identifier: GPL-2.0
/*
 * Volume Management Device driver
 * Copyright (c) 2015, Intel Corporation.
 */

#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqchip/irq-msi-lib.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/msi.h>
#include <linux/pci.h>
#include <linux/pci-acpi.h>
#include <linux/pci-ecam.h>
#include <linux/srcu.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>

#include <xen/xen.h>

#include <asm/irqdomain.h>

#define VMD_CFGBAR      0
#define VMD_MEMBAR1     2
#define VMD_MEMBAR2     4

#define PCI_REG_VMCAP           0x40
#define BUS_RESTRICT_CAP(vmcap) (vmcap & 0x1)
#define PCI_REG_VMCONFIG        0x44
#define BUS_RESTRICT_CFG(vmcfg) ((vmcfg >> 8) & 0x3)
#define VMCONFIG_MSI_REMAP      0x2
#define PCI_REG_VMLOCK          0x70
#define MB2_SHADOW_EN(vmlock)   (vmlock & 0x2)

#define MB2_SHADOW_OFFSET       0x2000
#define MB2_SHADOW_SIZE         16

enum vmd_features {
        /*
         * Device may contain registers which hint the physical location of the
         * membars, in order to allow proper address translation during
         * resource assignment to enable guest virtualization
         */
        VMD_FEAT_HAS_MEMBAR_SHADOW              = (1 << 0),

        /*
         * Device may provide root port configuration information which limits
         * bus numbering
         */
        VMD_FEAT_HAS_BUS_RESTRICTIONS           = (1 << 1),

        /*
         * Device contains physical location shadow registers in
         * vendor-specific capability space
         */
        VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP        = (1 << 2),

        /*
         * Device may use MSI-X vector 0 for software triggering and will not
         * be used for MSI remapping
         */
        VMD_FEAT_OFFSET_FIRST_VECTOR            = (1 << 3),

        /*
         * Device can bypass remapping MSI-X transactions into its MSI-X table,
         * avoiding the requirement of a VMD MSI domain for child device
         * interrupt handling.
         */
        VMD_FEAT_CAN_BYPASS_MSI_REMAP           = (1 << 4),

        /*
         * Enable ASPM on the PCIE root ports and set the default LTR of the
         * storage devices on platforms where these values are not configured by
         * BIOS. This is needed for laptops, which require these settings for
         * proper power management of the SoC.
         */
        VMD_FEAT_BIOS_PM_QUIRK          = (1 << 5),
};

#define VMD_BIOS_PM_QUIRK_LTR   0x1003  /* 3145728 ns */

#define VMD_FEATS_CLIENT        (VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP |     \
                                 VMD_FEAT_HAS_BUS_RESTRICTIONS |        \
                                 VMD_FEAT_OFFSET_FIRST_VECTOR |         \
                                 VMD_FEAT_BIOS_PM_QUIRK)

static DEFINE_IDA(vmd_instance_ida);

/*
 * Lock for manipulating VMD IRQ lists.
 */
static DEFINE_RAW_SPINLOCK(list_lock);

/**
 * struct vmd_irq - private data to map driver IRQ to the VMD shared vector
 * @node:       list item for parent traversal.
 * @irq:        back pointer to parent.
 * @enabled:    true if driver enabled IRQ
 * @virq:       the virtual IRQ value provided to the requesting driver.
 *
 * Every MSI/MSI-X IRQ requested for a device in a VMD domain will be mapped to
 * a VMD IRQ using this structure.
 */
struct vmd_irq {
        struct list_head        node;
        struct vmd_irq_list     *irq;
        bool                    enabled;
        unsigned int            virq;
};

/**
 * struct vmd_irq_list - list of driver requested IRQs mapping to a VMD vector
 * @irq_list:   the list of irq's the VMD one demuxes to.
 * @srcu:       SRCU struct for local synchronization.
 * @count:      number of child IRQs assigned to this vector; used to track
 *              sharing.
 * @virq:       The underlying VMD Linux interrupt number
 */
struct vmd_irq_list {
        struct list_head        irq_list;
        struct srcu_struct      srcu;
        unsigned int            count;
        unsigned int            virq;
};

struct vmd_dev {
        struct pci_dev          *dev;

        raw_spinlock_t          cfg_lock;
        void __iomem            *cfgbar;

        int msix_count;
        struct vmd_irq_list     *irqs;

        struct pci_sysdata      sysdata;
        struct resource         resources[3];
        struct irq_domain       *irq_domain;
        struct pci_bus          *bus;
        u8                      busn_start;
        u8                      first_vec;
        char                    *name;
        int                     instance;
};

static inline struct vmd_dev *vmd_from_bus(struct pci_bus *bus)
{
        return container_of(bus->sysdata, struct vmd_dev, sysdata);
}

static inline unsigned int index_from_irqs(struct vmd_dev *vmd,
                                           struct vmd_irq_list *irqs)
{
        return irqs - vmd->irqs;
}

/*
 * Drivers managing a device in a VMD domain allocate their own IRQs as before,
 * but the MSI entry for the hardware it's driving will be programmed with a
 * destination ID for the VMD MSI-X table.  The VMD muxes interrupts in its
 * domain into one of its own, and the VMD driver de-muxes these for the
 * handlers sharing that VMD IRQ.  The vmd irq_domain provides the operations
 * and irq_chip to set this up.
 */
static void vmd_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
        struct vmd_irq *vmdirq = data->chip_data;
        struct vmd_irq_list *irq = vmdirq->irq;
        struct vmd_dev *vmd = irq_data_get_irq_handler_data(data);

        memset(msg, 0, sizeof(*msg));
        msg->address_hi = X86_MSI_BASE_ADDRESS_HIGH;
        msg->arch_addr_lo.base_address = X86_MSI_BASE_ADDRESS_LOW;
        msg->arch_addr_lo.destid_0_7 = index_from_irqs(vmd, irq);
}

static void vmd_irq_enable(struct irq_data *data)
{
        struct vmd_irq *vmdirq = data->chip_data;

        scoped_guard(raw_spinlock_irqsave, &list_lock) {
                WARN_ON(vmdirq->enabled);
                list_add_tail_rcu(&vmdirq->node, &vmdirq->irq->irq_list);
                vmdirq->enabled = true;
        }
}

static void vmd_pci_msi_enable(struct irq_data *data)
{
        vmd_irq_enable(data->parent_data);
        data->chip->irq_unmask(data);
}

static unsigned int vmd_pci_msi_startup(struct irq_data *data)
{
        vmd_pci_msi_enable(data);
        return 0;
}

static void vmd_irq_disable(struct irq_data *data)
{
        struct vmd_irq *vmdirq = data->chip_data;

        scoped_guard(raw_spinlock_irqsave, &list_lock) {
                if (vmdirq->enabled) {
                        list_del_rcu(&vmdirq->node);
                        vmdirq->enabled = false;
                }
        }
}

static void vmd_pci_msi_disable(struct irq_data *data)
{
        data->chip->irq_mask(data);
        vmd_irq_disable(data->parent_data);
}

static void vmd_pci_msi_shutdown(struct irq_data *data)
{
        vmd_pci_msi_disable(data);
}

static struct irq_chip vmd_msi_controller = {
        .name                   = "VMD-MSI",
        .irq_compose_msi_msg    = vmd_compose_msi_msg,
};

/*
 * XXX: We can be even smarter selecting the best IRQ once we solve the
 * affinity problem.
 */
static struct vmd_irq_list *vmd_next_irq(struct vmd_dev *vmd, struct msi_desc *desc)
{
        int i, best;

        if (vmd->msix_count == 1 + vmd->first_vec)
                return &vmd->irqs[vmd->first_vec];

        /*
         * White list for fast-interrupt handlers. All others will share the
         * "slow" interrupt vector.
         */
        switch (msi_desc_to_pci_dev(desc)->class) {
        case PCI_CLASS_STORAGE_EXPRESS:
                break;
        default:
                return &vmd->irqs[vmd->first_vec];
        }

        scoped_guard(raw_spinlock_irq, &list_lock) {
                best = vmd->first_vec + 1;
                for (i = best; i < vmd->msix_count; i++)
                        if (vmd->irqs[i].count < vmd->irqs[best].count)
                                best = i;
                vmd->irqs[best].count++;
        }

        return &vmd->irqs[best];
}

static void vmd_msi_free(struct irq_domain *domain, unsigned int virq,
                         unsigned int nr_irqs);

static int vmd_msi_alloc(struct irq_domain *domain, unsigned int virq,
                         unsigned int nr_irqs, void *arg)
{
        struct msi_desc *desc = ((msi_alloc_info_t *)arg)->desc;
        struct vmd_dev *vmd = domain->host_data;
        struct vmd_irq *vmdirq;

        for (int i = 0; i < nr_irqs; ++i) {
                vmdirq = kzalloc_obj(*vmdirq);
                if (!vmdirq) {
                        vmd_msi_free(domain, virq, i);
                        return -ENOMEM;
                }

                INIT_LIST_HEAD(&vmdirq->node);
                vmdirq->irq = vmd_next_irq(vmd, desc);
                vmdirq->virq = virq + i;

                irq_domain_set_info(domain, virq + i, vmdirq->irq->virq,
                                    &vmd_msi_controller, vmdirq,
                                    handle_untracked_irq, vmd, NULL);
        }

        return 0;
}

static void vmd_msi_free(struct irq_domain *domain, unsigned int virq,
                         unsigned int nr_irqs)
{
        struct irq_data *irq_data;
        struct vmd_irq *vmdirq;

        for (int i = 0; i < nr_irqs; ++i) {
                irq_data = irq_domain_get_irq_data(domain, virq + i);
                vmdirq = irq_data->chip_data;

                synchronize_srcu(&vmdirq->irq->srcu);

                /* XXX: Potential optimization to rebalance */
                scoped_guard(raw_spinlock_irq, &list_lock)
                        vmdirq->irq->count--;

                kfree(vmdirq);
        }
}

static const struct irq_domain_ops vmd_msi_domain_ops = {
        .alloc          = vmd_msi_alloc,
        .free           = vmd_msi_free,
};

static bool vmd_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
                                  struct irq_domain *real_parent,
                                  struct msi_domain_info *info)
{
        if (!msi_lib_init_dev_msi_info(dev, domain, real_parent, info))
                return false;

        info->chip->irq_startup         = vmd_pci_msi_startup;
        info->chip->irq_shutdown        = vmd_pci_msi_shutdown;
        info->chip->irq_enable          = vmd_pci_msi_enable;
        info->chip->irq_disable         = vmd_pci_msi_disable;
        return true;
}

#define VMD_MSI_FLAGS_SUPPORTED (MSI_GENERIC_FLAGS_MASK | MSI_FLAG_PCI_MSIX)
#define VMD_MSI_FLAGS_REQUIRED  (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_NO_AFFINITY)

static const struct msi_parent_ops vmd_msi_parent_ops = {
        .supported_flags        = VMD_MSI_FLAGS_SUPPORTED,
        .required_flags         = VMD_MSI_FLAGS_REQUIRED,
        .bus_select_token       = DOMAIN_BUS_VMD_MSI,
        .bus_select_mask        = MATCH_PCI_MSI,
        .prefix                 = "VMD-",
        .init_dev_msi_info      = vmd_init_dev_msi_info,
};

static int vmd_create_irq_domain(struct vmd_dev *vmd)
{
        struct irq_domain_info info = {
                .size           = vmd->msix_count,
                .ops            = &vmd_msi_domain_ops,
                .host_data      = vmd,
        };

        info.fwnode = irq_domain_alloc_named_id_fwnode("VMD-MSI",
                                                       vmd->sysdata.domain);
        if (!info.fwnode)
                return -ENODEV;

        vmd->irq_domain = msi_create_parent_irq_domain(&info,
                                                       &vmd_msi_parent_ops);
        if (!vmd->irq_domain) {
                irq_domain_free_fwnode(info.fwnode);
                return -ENODEV;
        }

        return 0;
}

static void vmd_set_msi_remapping(struct vmd_dev *vmd, bool enable)
{
        u16 reg;

        pci_read_config_word(vmd->dev, PCI_REG_VMCONFIG, &reg);
        reg = enable ? (reg & ~VMCONFIG_MSI_REMAP) :
                       (reg | VMCONFIG_MSI_REMAP);
        pci_write_config_word(vmd->dev, PCI_REG_VMCONFIG, reg);
}

static void vmd_remove_irq_domain(struct vmd_dev *vmd)
{
        /*
         * Some production BIOS won't enable remapping between soft reboots.
         * Ensure remapping is restored before unloading the driver.
         */
        if (!vmd->msix_count)
                vmd_set_msi_remapping(vmd, true);

        if (vmd->irq_domain) {
                struct fwnode_handle *fn = vmd->irq_domain->fwnode;

                irq_domain_remove(vmd->irq_domain);
                irq_domain_free_fwnode(fn);
        }
}

static void __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
                                  unsigned int devfn, int reg, int len)
{
        unsigned int busnr_ecam = bus->number - vmd->busn_start;
        u32 offset = PCIE_ECAM_OFFSET(busnr_ecam, devfn, reg);

        if (offset + len >= resource_size(&vmd->dev->resource[VMD_CFGBAR]))
                return NULL;

        return vmd->cfgbar + offset;
}

/*
 * CPU may deadlock if config space is not serialized on some versions of this
 * hardware, so all config space access is done under a spinlock.
 */
static int vmd_pci_read(struct pci_bus *bus, unsigned int devfn, int reg,
                        int len, u32 *value)
{
        struct vmd_dev *vmd = vmd_from_bus(bus);
        void __iomem *addr = vmd_cfg_addr(vmd, bus, devfn, reg, len);

        if (!addr)
                return -EFAULT;

        guard(raw_spinlock_irqsave)(&vmd->cfg_lock);
        switch (len) {
        case 1:
                *value = readb(addr);
                return 0;
        case 2:
                *value = readw(addr);
                return 0;
        case 4:
                *value = readl(addr);
                return 0;
        default:
                return -EINVAL;
        }
}

/*
 * VMD h/w converts non-posted config writes to posted memory writes. The
 * read-back in this function forces the completion so it returns only after
 * the config space was written, as expected.
 */
static int vmd_pci_write(struct pci_bus *bus, unsigned int devfn, int reg,
                         int len, u32 value)
{
        struct vmd_dev *vmd = vmd_from_bus(bus);
        void __iomem *addr = vmd_cfg_addr(vmd, bus, devfn, reg, len);

        if (!addr)
                return -EFAULT;

        guard(raw_spinlock_irqsave)(&vmd->cfg_lock);
        switch (len) {
        case 1:
                writeb(value, addr);
                readb(addr);
                return 0;
        case 2:
                writew(value, addr);
                readw(addr);
                return 0;
        case 4:
                writel(value, addr);
                readl(addr);
                return 0;
        default:
                return -EINVAL;
        }
}

static struct pci_ops vmd_ops = {
        .read           = vmd_pci_read,
        .write          = vmd_pci_write,
};

#ifdef CONFIG_ACPI
static struct acpi_device *vmd_acpi_find_companion(struct pci_dev *pci_dev)
{
        struct pci_host_bridge *bridge;
        u32 busnr, addr;

        if (pci_dev->bus->ops != &vmd_ops)
                return NULL;

        bridge = pci_find_host_bridge(pci_dev->bus);
        busnr = pci_dev->bus->number - bridge->bus->number;
        /*
         * The address computation below is only applicable to relative bus
         * numbers below 32.
         */
        if (busnr > 31)
                return NULL;

        addr = (busnr << 24) | ((u32)pci_dev->devfn << 16) | 0x8000FFFFU;

        dev_dbg(&pci_dev->dev, "Looking for ACPI companion (address 0x%x)\n",
                addr);

        return acpi_find_child_device(ACPI_COMPANION(bridge->dev.parent), addr,
                                      false);
}

static bool hook_installed;

static void vmd_acpi_begin(void)
{
        if (pci_acpi_set_companion_lookup_hook(vmd_acpi_find_companion))
                return;

        hook_installed = true;
}

static void vmd_acpi_end(void)
{
        if (!hook_installed)
                return;

        pci_acpi_clear_companion_lookup_hook();
        hook_installed = false;
}
#else
static inline void vmd_acpi_begin(void) { }
static inline void vmd_acpi_end(void) { }
#endif /* CONFIG_ACPI */

static void vmd_domain_reset(struct vmd_dev *vmd)
{
        u16 bus, max_buses = resource_size(&vmd->resources[0]);
        u8 dev, functions, fn, hdr_type;
        char __iomem *base;

        for (bus = 0; bus < max_buses; bus++) {
                for (dev = 0; dev < 32; dev++) {
                        base = vmd->cfgbar + PCIE_ECAM_OFFSET(bus,
                                                PCI_DEVFN(dev, 0), 0);

                        hdr_type = readb(base + PCI_HEADER_TYPE);

                        functions = (hdr_type & PCI_HEADER_TYPE_MFD) ? 8 : 1;
                        for (fn = 0; fn < functions; fn++) {
                                base = vmd->cfgbar + PCIE_ECAM_OFFSET(bus,
                                                PCI_DEVFN(dev, fn), 0);

                                hdr_type = readb(base + PCI_HEADER_TYPE) &
                                                PCI_HEADER_TYPE_MASK;

                                if (hdr_type != PCI_HEADER_TYPE_BRIDGE ||
                                    (readw(base + PCI_CLASS_DEVICE) !=
                                     PCI_CLASS_BRIDGE_PCI))
                                        continue;

                                /*
                                 * Temporarily disable the I/O range before updating
                                 * PCI_IO_BASE.
                                 */
                                writel(0x0000ffff, base + PCI_IO_BASE_UPPER16);
                                /* Update lower 16 bits of I/O base/limit */
                                writew(0x00f0, base + PCI_IO_BASE);
                                /* Update upper 16 bits of I/O base/limit */
                                writel(0, base + PCI_IO_BASE_UPPER16);

                                /* MMIO Base/Limit */
                                writel(0x0000fff0, base + PCI_MEMORY_BASE);

                                /* Prefetchable MMIO Base/Limit */
                                writel(0, base + PCI_PREF_LIMIT_UPPER32);
                                writel(0x0000fff0, base + PCI_PREF_MEMORY_BASE);
                                writel(0xffffffff, base + PCI_PREF_BASE_UPPER32);
                        }
                }
        }
}

static void vmd_attach_resources(struct vmd_dev *vmd)
{
        vmd->dev->resource[VMD_MEMBAR1].child = &vmd->resources[1];
        vmd->dev->resource[VMD_MEMBAR2].child = &vmd->resources[2];
}

static void vmd_detach_resources(struct vmd_dev *vmd)
{
        vmd->dev->resource[VMD_MEMBAR1].child = NULL;
        vmd->dev->resource[VMD_MEMBAR2].child = NULL;
}

static int vmd_get_phys_offsets(struct vmd_dev *vmd, bool native_hint,
                                resource_size_t *offset1,
                                resource_size_t *offset2)
{
        struct pci_dev *dev = vmd->dev;
        u64 phys1, phys2;

        if (native_hint) {
                u32 vmlock;
                int ret;

                ret = pci_read_config_dword(dev, PCI_REG_VMLOCK, &vmlock);
                if (ret || PCI_POSSIBLE_ERROR(vmlock))
                        return -ENODEV;

                if (MB2_SHADOW_EN(vmlock)) {
                        void __iomem *membar2;

                        membar2 = pci_iomap(dev, VMD_MEMBAR2, 0);
                        if (!membar2)
                                return -ENOMEM;
                        phys1 = readq(membar2 + MB2_SHADOW_OFFSET);
                        phys2 = readq(membar2 + MB2_SHADOW_OFFSET + 8);
                        pci_iounmap(dev, membar2);
                } else
                        return 0;
        } else {
                /* Hypervisor-Emulated Vendor-Specific Capability */
                int pos = pci_find_capability(dev, PCI_CAP_ID_VNDR);
                u32 reg, regu;

                pci_read_config_dword(dev, pos + 4, &reg);

                /* "SHDW" */
                if (pos && reg == 0x53484457) {
                        pci_read_config_dword(dev, pos + 8, &reg);
                        pci_read_config_dword(dev, pos + 12, &regu);
                        phys1 = (u64) regu << 32 | reg;

                        pci_read_config_dword(dev, pos + 16, &reg);
                        pci_read_config_dword(dev, pos + 20, &regu);
                        phys2 = (u64) regu << 32 | reg;
                } else
                        return 0;
        }

        *offset1 = dev->resource[VMD_MEMBAR1].start -
                        (phys1 & PCI_BASE_ADDRESS_MEM_MASK);
        *offset2 = dev->resource[VMD_MEMBAR2].start -
                        (phys2 & PCI_BASE_ADDRESS_MEM_MASK);

        return 0;
}

static int vmd_get_bus_number_start(struct vmd_dev *vmd)
{
        struct pci_dev *dev = vmd->dev;
        u16 reg;

        pci_read_config_word(dev, PCI_REG_VMCAP, &reg);
        if (BUS_RESTRICT_CAP(reg)) {
                pci_read_config_word(dev, PCI_REG_VMCONFIG, &reg);

                switch (BUS_RESTRICT_CFG(reg)) {
                case 0:
                        vmd->busn_start = 0;
                        break;
                case 1:
                        vmd->busn_start = 128;
                        break;
                case 2:
                        vmd->busn_start = 224;
                        break;
                default:
                        pci_err(dev, "Unknown Bus Offset Setting (%d)\n",
                                BUS_RESTRICT_CFG(reg));
                        return -ENODEV;
                }
        }

        return 0;
}

static irqreturn_t vmd_irq(int irq, void *data)
{
        struct vmd_irq_list *irqs = data;
        struct vmd_irq *vmdirq;
        int idx;

        idx = srcu_read_lock(&irqs->srcu);
        list_for_each_entry_rcu(vmdirq, &irqs->irq_list, node)
                generic_handle_irq(vmdirq->virq);
        srcu_read_unlock(&irqs->srcu, idx);

        return IRQ_HANDLED;
}

static int vmd_alloc_irqs(struct vmd_dev *vmd)
{
        struct pci_dev *dev = vmd->dev;
        int i, err;

        vmd->msix_count = pci_msix_vec_count(dev);
        if (vmd->msix_count < 0)
                return -ENODEV;

        vmd->msix_count = pci_alloc_irq_vectors(dev, vmd->first_vec + 1,
                                                vmd->msix_count, PCI_IRQ_MSIX);
        if (vmd->msix_count < 0)
                return vmd->msix_count;

        vmd->irqs = devm_kcalloc(&dev->dev, vmd->msix_count, sizeof(*vmd->irqs),
                                 GFP_KERNEL);
        if (!vmd->irqs)
                return -ENOMEM;

        for (i = 0; i < vmd->msix_count; i++) {
                err = init_srcu_struct(&vmd->irqs[i].srcu);
                if (err)
                        return err;

                INIT_LIST_HEAD(&vmd->irqs[i].irq_list);
                vmd->irqs[i].virq = pci_irq_vector(dev, i);
                err = devm_request_irq(&dev->dev, vmd->irqs[i].virq,
                                       vmd_irq, IRQF_NO_THREAD,
                                       vmd->name, &vmd->irqs[i]);
                if (err)
                        return err;
        }

        return 0;
}

/*
 * Since VMD is an aperture to regular PCIe root ports, only allow it to
 * control features that the OS is allowed to control on the physical PCI bus.
 */
static void vmd_copy_host_bridge_flags(struct pci_host_bridge *root_bridge,
                                       struct pci_host_bridge *vmd_bridge)
{
        vmd_bridge->native_pcie_hotplug = root_bridge->native_pcie_hotplug;
        vmd_bridge->native_shpc_hotplug = root_bridge->native_shpc_hotplug;
        vmd_bridge->native_aer = root_bridge->native_aer;
        vmd_bridge->native_pme = root_bridge->native_pme;
        vmd_bridge->native_ltr = root_bridge->native_ltr;
        vmd_bridge->native_dpc = root_bridge->native_dpc;
}

/*
 * Enable ASPM and LTR settings on devices that aren't configured by BIOS.
 */
static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata)
{
        unsigned long features = *(unsigned long *)userdata;
        u16 ltr = VMD_BIOS_PM_QUIRK_LTR;
        u32 ltr_reg;
        int pos;

        if (!(features & VMD_FEAT_BIOS_PM_QUIRK))
                return 0;

        pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_LTR);
        if (!pos)
                goto out_state_change;

        /*
         * Skip if the max snoop LTR is non-zero, indicating BIOS has set it
         * so the LTR quirk is not needed.
         */
        pci_read_config_dword(pdev, pos + PCI_LTR_MAX_SNOOP_LAT, &ltr_reg);
        if (!!(ltr_reg & (PCI_LTR_VALUE_MASK | PCI_LTR_SCALE_MASK)))
                goto out_state_change;

        /*
         * Set the default values to the maximum required by the platform to
         * allow the deepest power management savings. Write as a DWORD where
         * the lower word is the max snoop latency and the upper word is the
         * max non-snoop latency.
         */
        ltr_reg = (ltr << 16) | ltr;
        pci_write_config_dword(pdev, pos + PCI_LTR_MAX_SNOOP_LAT, ltr_reg);
        pci_info(pdev, "VMD: Default LTR value set by driver\n");

out_state_change:
        /*
         * Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per
         * PCIe r6.0, sec 5.5.4.
         */
        pci_set_power_state_locked(pdev, PCI_D0);
        pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL);
        return 0;
}

static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
{
        struct pci_sysdata *sd = &vmd->sysdata;
        struct resource *res;
        u32 upper_bits;
        unsigned long flags;
        LIST_HEAD(resources);
        resource_size_t offset[2] = {0};
        resource_size_t membar2_offset = 0x2000;
        struct pci_bus *child;
        struct pci_dev *dev;
        int ret;

        /*
         * Shadow registers may exist in certain VMD device ids which allow
         * guests to correctly assign host physical addresses to the root ports
         * and child devices. These registers will either return the host value
         * or 0, depending on an enable bit in the VMD device.
         */
        if (features & VMD_FEAT_HAS_MEMBAR_SHADOW) {
                membar2_offset = MB2_SHADOW_OFFSET + MB2_SHADOW_SIZE;
                ret = vmd_get_phys_offsets(vmd, true, &offset[0], &offset[1]);
                if (ret)
                        return ret;
        } else if (features & VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP) {
                ret = vmd_get_phys_offsets(vmd, false, &offset[0], &offset[1]);
                if (ret)
                        return ret;
        }

        /*
         * Certain VMD devices may have a root port configuration option which
         * limits the bus range to between 0-127, 128-255, or 224-255
         */
        if (features & VMD_FEAT_HAS_BUS_RESTRICTIONS) {
                ret = vmd_get_bus_number_start(vmd);
                if (ret)
                        return ret;
        }

        res = &vmd->dev->resource[VMD_CFGBAR];
        vmd->resources[0] = (struct resource) {
                .name  = "VMD CFGBAR",
                .start = vmd->busn_start,
                .end   = vmd->busn_start + (resource_size(res) >> 20) - 1,
                .flags = IORESOURCE_BUS | IORESOURCE_PCI_FIXED,
        };

        /*
         * If the window is below 4GB, clear IORESOURCE_MEM_64 so we can
         * put 32-bit resources in the window.
         *
         * There's no hardware reason why a 64-bit window *couldn't*
         * contain a 32-bit resource, but pbus_size_mem() computes the
         * bridge window size assuming a 64-bit window will contain no
         * 32-bit resources.  __pci_assign_resource() enforces that
         * artificial restriction to make sure everything will fit.
         *
         * The only way we could use a 64-bit non-prefetchable MEMBAR is
         * if its address is <4GB so that we can convert it to a 32-bit
         * resource.  To be visible to the host OS, all VMD endpoints must
         * be initially configured by platform BIOS, which includes setting
         * up these resources.  We can assume the device is configured
         * according to the platform needs.
         */
        res = &vmd->dev->resource[VMD_MEMBAR1];
        upper_bits = upper_32_bits(res->end);
        flags = res->flags & ~IORESOURCE_SIZEALIGN;
        if (!upper_bits)
                flags &= ~IORESOURCE_MEM_64;
        vmd->resources[1] = (struct resource) {
                .name  = "VMD MEMBAR1",
                .start = res->start,
                .end   = res->end,
                .flags = flags,
                .parent = res,
        };

        res = &vmd->dev->resource[VMD_MEMBAR2];
        upper_bits = upper_32_bits(res->end);
        flags = res->flags & ~IORESOURCE_SIZEALIGN;
        if (!upper_bits)
                flags &= ~IORESOURCE_MEM_64;
        vmd->resources[2] = (struct resource) {
                .name  = "VMD MEMBAR2",
                .start = res->start + membar2_offset,
                .end   = res->end,
                .flags = flags,
                .parent = res,
        };

        /*
         * Currently MSI remapping must be enabled in guest passthrough mode
         * due to some missing interrupt remapping plumbing. This is probably
         * acceptable because the guest is usually CPU-limited and MSI
         * remapping doesn't become a performance bottleneck.
         */
        if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
            offset[0] || offset[1]) {
                ret = vmd_alloc_irqs(vmd);
                if (ret)
                        return ret;

                vmd_set_msi_remapping(vmd, true);

                ret = vmd_create_irq_domain(vmd);
                if (ret)
                        return ret;
        } else {
                vmd_set_msi_remapping(vmd, false);
        }

        pci_add_resource(&resources, &vmd->resources[0]);
        pci_add_resource_offset(&resources, &vmd->resources[1], offset[0]);
        pci_add_resource_offset(&resources, &vmd->resources[2], offset[1]);

        sd->vmd_dev = vmd->dev;

        /*
         * Emulated domains start at 0x10000 to not clash with ACPI _SEG
         * domains.  Per ACPI r6.0, sec 6.5.6, _SEG returns an integer, of
         * which the lower 16 bits are the PCI Segment Group (domain) number.
         * Other bits are currently reserved.
         */
        sd->domain = pci_bus_find_emul_domain_nr(0, 0x10000, INT_MAX);
        if (sd->domain < 0)
                return sd->domain;

        sd->node = pcibus_to_node(vmd->dev->bus);

        vmd->bus = pci_create_root_bus(&vmd->dev->dev, vmd->busn_start,
                                       &vmd_ops, sd, &resources);
        if (!vmd->bus) {
                pci_bus_release_emul_domain_nr(sd->domain);
                pci_free_resource_list(&resources);
                vmd_remove_irq_domain(vmd);
                return -ENODEV;
        }

        vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
                                   to_pci_host_bridge(vmd->bus->bridge));

        vmd_attach_resources(vmd);
        if (vmd->irq_domain)
                dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
        else
                dev_set_msi_domain(&vmd->bus->dev,
                                   dev_get_msi_domain(&vmd->dev->dev));

        WARN(sysfs_create_link(&vmd->dev->dev.kobj, &vmd->bus->dev.kobj,
                               "domain"), "Can't create symlink to domain\n");

        vmd_acpi_begin();

        pci_scan_child_bus(vmd->bus);
        vmd_domain_reset(vmd);

        /* When Intel VMD is enabled, the OS does not discover the Root Ports
         * owned by Intel VMD within the MMCFG space. pci_reset_bus() applies
         * a reset to the parent of the PCI device supplied as argument. This
         * is why we pass a child device, so the reset can be triggered at
         * the Intel bridge level and propagated to all the children in the
         * hierarchy.
         */
        list_for_each_entry(child, &vmd->bus->children, node) {
                if (!list_empty(&child->devices)) {
                        dev = list_first_entry(&child->devices,
                                               struct pci_dev, bus_list);
                        ret = pci_reset_bus(dev);
                        if (ret)
                                pci_warn(dev, "can't reset device: %d\n", ret);

                        break;
                }
        }

        pci_assign_unassigned_bus_resources(vmd->bus);

        pci_walk_bus(vmd->bus, vmd_pm_enable_quirk, &features);

        /*
         * VMD root buses are virtual and don't return true on pci_is_pcie()
         * and will fail pcie_bus_configure_settings() early. It can instead be
         * run on each of the real root ports.
         */
        list_for_each_entry(child, &vmd->bus->children, node)
                pcie_bus_configure_settings(child);

        pci_bus_add_devices(vmd->bus);

        vmd_acpi_end();
        return 0;
}

static int vmd_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
        unsigned long features = (unsigned long) id->driver_data;
        struct vmd_dev *vmd;
        int err;

        if (xen_domain()) {
                /*
                 * Xen doesn't have knowledge about devices in the VMD bus
                 * because the config space of devices behind the VMD bridge is
                 * not known to Xen, and hence Xen cannot discover or configure
                 * them in any way.
                 *
                 * Bypass of MSI remapping won't work in that case as direct
                 * write by Linux to the MSI entries won't result in functional
                 * interrupts, as Xen is the entity that manages the host
                 * interrupt controller and must configure interrupts.  However
                 * multiplexing of interrupts by the VMD bridge will work under
                 * Xen, so force the usage of that mode which must always be
                 * supported by VMD bridges.
                 */
                features &= ~VMD_FEAT_CAN_BYPASS_MSI_REMAP;
        }

        if (resource_size(&dev->resource[VMD_CFGBAR]) < (1 << 20))
                return -ENOMEM;

        vmd = devm_kzalloc(&dev->dev, sizeof(*vmd), GFP_KERNEL);
        if (!vmd)
                return -ENOMEM;

        vmd->dev = dev;
        vmd->sysdata.domain = PCI_DOMAIN_NR_NOT_SET;
        vmd->instance = ida_alloc(&vmd_instance_ida, GFP_KERNEL);
        if (vmd->instance < 0)
                return vmd->instance;

        vmd->name = devm_kasprintf(&dev->dev, GFP_KERNEL, "vmd%d",
                                   vmd->instance);
        if (!vmd->name) {
                err = -ENOMEM;
                goto out_release_instance;
        }

        err = pcim_enable_device(dev);
        if (err < 0)
                goto out_release_instance;

        vmd->cfgbar = pcim_iomap(dev, VMD_CFGBAR, 0);
        if (!vmd->cfgbar) {
                err = -ENOMEM;
                goto out_release_instance;
        }

        pci_set_master(dev);
        if (dma_set_mask_and_coherent(&dev->dev, DMA_BIT_MASK(64)) &&
            dma_set_mask_and_coherent(&dev->dev, DMA_BIT_MASK(32))) {
                err = -ENODEV;
                goto out_release_instance;
        }

        if (features & VMD_FEAT_OFFSET_FIRST_VECTOR)
                vmd->first_vec = 1;

        raw_spin_lock_init(&vmd->cfg_lock);
        pci_set_drvdata(dev, vmd);
        err = vmd_enable_domain(vmd, features);
        if (err)
                goto out_release_instance;

        dev_info(&vmd->dev->dev, "Bound to PCI domain %04x\n",
                 vmd->sysdata.domain);
        return 0;

 out_release_instance:
        ida_free(&vmd_instance_ida, vmd->instance);
        return err;
}

static void vmd_cleanup_srcu(struct vmd_dev *vmd)
{
        int i;

        for (i = 0; i < vmd->msix_count; i++)
                cleanup_srcu_struct(&vmd->irqs[i].srcu);
}

static void vmd_remove(struct pci_dev *dev)
{
        struct vmd_dev *vmd = pci_get_drvdata(dev);

        pci_stop_root_bus(vmd->bus);
        sysfs_remove_link(&vmd->dev->dev.kobj, "domain");
        pci_remove_root_bus(vmd->bus);
        vmd_cleanup_srcu(vmd);
        vmd_detach_resources(vmd);
        vmd_remove_irq_domain(vmd);
        ida_free(&vmd_instance_ida, vmd->instance);
        pci_bus_release_emul_domain_nr(vmd->sysdata.domain);
}

static void vmd_shutdown(struct pci_dev *dev)
{
        struct vmd_dev *vmd = pci_get_drvdata(dev);

        vmd_remove_irq_domain(vmd);
}

#ifdef CONFIG_PM_SLEEP
static int vmd_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct vmd_dev *vmd = pci_get_drvdata(pdev);
        int i;

        for (i = 0; i < vmd->msix_count; i++)
                devm_free_irq(dev, vmd->irqs[i].virq, &vmd->irqs[i]);

        return 0;
}

static int vmd_resume(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct vmd_dev *vmd = pci_get_drvdata(pdev);
        int err, i;

        vmd_set_msi_remapping(vmd, !!vmd->irq_domain);

        for (i = 0; i < vmd->msix_count; i++) {
                err = devm_request_irq(dev, vmd->irqs[i].virq,
                                       vmd_irq, IRQF_NO_THREAD,
                                       vmd->name, &vmd->irqs[i]);
                if (err)
                        return err;
        }

        return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(vmd_dev_pm_ops, vmd_suspend, vmd_resume);

static const struct pci_device_id vmd_ids[] = {
        {PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_VMD_201D),
                .driver_data = VMD_FEAT_HAS_MEMBAR_SHADOW_VSCAP,},
        {PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_VMD_28C0),
                .driver_data = VMD_FEAT_HAS_MEMBAR_SHADOW |
                                VMD_FEAT_HAS_BUS_RESTRICTIONS |
                                VMD_FEAT_CAN_BYPASS_MSI_REMAP,},
        {PCI_VDEVICE(INTEL, 0x467f),
                .driver_data = VMD_FEATS_CLIENT,},
        {PCI_VDEVICE(INTEL, 0x4c3d),
                .driver_data = VMD_FEATS_CLIENT,},
        {PCI_VDEVICE(INTEL, 0xa77f),
                .driver_data = VMD_FEATS_CLIENT,},
        {PCI_VDEVICE(INTEL, 0x7d0b),
                .driver_data = VMD_FEATS_CLIENT,},
        {PCI_VDEVICE(INTEL, 0xad0b),
                .driver_data = VMD_FEATS_CLIENT,},
        {PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_VMD_9A0B),
                .driver_data = VMD_FEATS_CLIENT,},
        {PCI_VDEVICE(INTEL, 0xb60b),
                .driver_data = VMD_FEATS_CLIENT,},
        {PCI_VDEVICE(INTEL, 0xb06f),
                .driver_data = VMD_FEATS_CLIENT,},
        {PCI_VDEVICE(INTEL, 0xb07f),
                .driver_data = VMD_FEATS_CLIENT,},
        {0,}
};
MODULE_DEVICE_TABLE(pci, vmd_ids);

static struct pci_driver vmd_drv = {
        .name           = "vmd",
        .id_table       = vmd_ids,
        .probe          = vmd_probe,
        .remove         = vmd_remove,
        .shutdown       = vmd_shutdown,
        .driver         = {
                .pm     = &vmd_dev_pm_ops,
        },
};
module_pci_driver(vmd_drv);

MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("Volume Management Device driver");
MODULE_LICENSE("GPL v2");
MODULE_VERSION("0.6");