// SPDX-License-Identifier: GPL-2.0
#include <linux/pci.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/wait.h>

#include "pci.h"

/*
 * This interrupt-safe spinlock protects all accesses to PCI
 * configuration space.
 */

DEFINE_RAW_SPINLOCK(pci_lock);

/*
 * Wrappers for all PCI configuration access functions.  They just check
 * alignment, do locking and call the low-level functions pointed to
 * by pci_dev->ops.
 */

#define PCI_byte_BAD 0
#define PCI_word_BAD (pos & 1)
#define PCI_dword_BAD (pos & 3)

#ifdef CONFIG_PCI_LOCKLESS_CONFIG
# define pci_lock_config(f)     do { (void)(f); } while (0)
# define pci_unlock_config(f)   do { (void)(f); } while (0)
#else
# define pci_lock_config(f)     raw_spin_lock_irqsave(&pci_lock, f)
# define pci_unlock_config(f)   raw_spin_unlock_irqrestore(&pci_lock, f)
#endif

#define PCI_OP_READ(size, type, len) \
int noinline pci_bus_read_config_##size \
        (struct pci_bus *bus, unsigned int devfn, int pos, type *value) \
{                                                                       \
        int res;                                                        \
        unsigned long flags;                                            \
        u32 data = 0;                                                   \
        if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
        pci_lock_config(flags);                                         \
        res = bus->ops->read(bus, devfn, pos, len, &data);              \
        *value = (type)data;                                            \
        pci_unlock_config(flags);                                       \
        return res;                                                     \
}

#define PCI_OP_WRITE(size, type, len) \
int noinline pci_bus_write_config_##size \
        (struct pci_bus *bus, unsigned int devfn, int pos, type value)  \
{                                                                       \
        int res;                                                        \
        unsigned long flags;                                            \
        if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
        pci_lock_config(flags);                                         \
        res = bus->ops->write(bus, devfn, pos, len, value);             \
        pci_unlock_config(flags);                                       \
        return res;                                                     \
}

PCI_OP_READ(byte, u8, 1)
PCI_OP_READ(word, u16, 2)
PCI_OP_READ(dword, u32, 4)
PCI_OP_WRITE(byte, u8, 1)
PCI_OP_WRITE(word, u16, 2)
PCI_OP_WRITE(dword, u32, 4)

EXPORT_SYMBOL(pci_bus_read_config_byte);
EXPORT_SYMBOL(pci_bus_read_config_word);
EXPORT_SYMBOL(pci_bus_read_config_dword);
EXPORT_SYMBOL(pci_bus_write_config_byte);
EXPORT_SYMBOL(pci_bus_write_config_word);
EXPORT_SYMBOL(pci_bus_write_config_dword);

int pci_generic_config_read(struct pci_bus *bus, unsigned int devfn,
                            int where, int size, u32 *val)
{
        void __iomem *addr;

        addr = bus->ops->map_bus(bus, devfn, where);
        if (!addr) {
                *val = ~0;
                return PCIBIOS_DEVICE_NOT_FOUND;
        }

        if (size == 1)
                *val = readb(addr);
        else if (size == 2)
                *val = readw(addr);
        else
                *val = readl(addr);

        return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_generic_config_read);

int pci_generic_config_write(struct pci_bus *bus, unsigned int devfn,
                             int where, int size, u32 val)
{
        void __iomem *addr;

        addr = bus->ops->map_bus(bus, devfn, where);
        if (!addr)
                return PCIBIOS_DEVICE_NOT_FOUND;

        if (size == 1)
                writeb(val, addr);
        else if (size == 2)
                writew(val, addr);
        else
                writel(val, addr);

        return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_generic_config_write);

int pci_generic_config_read32(struct pci_bus *bus, unsigned int devfn,
                              int where, int size, u32 *val)
{
        void __iomem *addr;

        addr = bus->ops->map_bus(bus, devfn, where & ~0x3);
        if (!addr) {
                *val = ~0;
                return PCIBIOS_DEVICE_NOT_FOUND;
        }

        *val = readl(addr);

        if (size <= 2)
                *val = (*val >> (8 * (where & 3))) & ((1 << (size * 8)) - 1);

        return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_generic_config_read32);

int pci_generic_config_write32(struct pci_bus *bus, unsigned int devfn,
                               int where, int size, u32 val)
{
        void __iomem *addr;
        u32 mask, tmp;

        addr = bus->ops->map_bus(bus, devfn, where & ~0x3);
        if (!addr)
                return PCIBIOS_DEVICE_NOT_FOUND;

        if (size == 4) {
                writel(val, addr);
                return PCIBIOS_SUCCESSFUL;
        }

        /*
         * In general, hardware that supports only 32-bit writes on PCI is
         * not spec-compliant.  For example, software may perform a 16-bit
         * write.  If the hardware only supports 32-bit accesses, we must
         * do a 32-bit read, merge in the 16 bits we intend to write,
         * followed by a 32-bit write.  If the 16 bits we *don't* intend to
         * write happen to have any RW1C (write-one-to-clear) bits set, we
         * just inadvertently cleared something we shouldn't have.
         */
        dev_warn_ratelimited(&bus->dev, "%d-byte config write to %04x:%02x:%02x.%d offset %#x may corrupt adjacent RW1C bits\n",
                             size, pci_domain_nr(bus), bus->number,
                             PCI_SLOT(devfn), PCI_FUNC(devfn), where);

        mask = ~(((1 << (size * 8)) - 1) << ((where & 0x3) * 8));
        tmp = readl(addr) & mask;
        tmp |= val << ((where & 0x3) * 8);
        writel(tmp, addr);

        return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_generic_config_write32);

/**
 * pci_bus_set_ops - Set raw operations of pci bus
 * @bus:        pci bus struct
 * @ops:        new raw operations
 *
 * Return previous raw operations
 */
struct pci_ops *pci_bus_set_ops(struct pci_bus *bus, struct pci_ops *ops)
{
        struct pci_ops *old_ops;
        unsigned long flags;

        raw_spin_lock_irqsave(&pci_lock, flags);
        old_ops = bus->ops;
        bus->ops = ops;
        raw_spin_unlock_irqrestore(&pci_lock, flags);
        return old_ops;
}
EXPORT_SYMBOL(pci_bus_set_ops);

/*
 * The following routines are to prevent the user from accessing PCI config
 * space when it's unsafe to do so.  Some devices require this during BIST and
 * we're required to prevent it during D-state transitions.
 *
 * We have a bit per device to indicate it's blocked and a global wait queue
 * for callers to sleep on until devices are unblocked.
 */
static DECLARE_WAIT_QUEUE_HEAD(pci_cfg_wait);

static noinline void pci_wait_cfg(struct pci_dev *dev)
        __must_hold(&pci_lock)
{
        do {
                raw_spin_unlock_irq(&pci_lock);
                wait_event(pci_cfg_wait, !dev->block_cfg_access);
                raw_spin_lock_irq(&pci_lock);
        } while (dev->block_cfg_access);
}

/* Returns 0 on success, negative values indicate error. */
#define PCI_USER_READ_CONFIG(size, type)                                        \
int pci_user_read_config_##size                                         \
        (struct pci_dev *dev, int pos, type *val)                       \
{                                                                       \
        int ret = PCIBIOS_SUCCESSFUL;                                   \
        u32 data = -1;                                                  \
        if (PCI_##size##_BAD)                                           \
                return -EINVAL;                                         \
        raw_spin_lock_irq(&pci_lock);                           \
        if (unlikely(dev->block_cfg_access))                            \
                pci_wait_cfg(dev);                                      \
        ret = dev->bus->ops->read(dev->bus, dev->devfn,                 \
                                        pos, sizeof(type), &data);      \
        raw_spin_unlock_irq(&pci_lock);                         \
        *val = (type)data;                                              \
        return pcibios_err_to_errno(ret);                               \
}                                                                       \
EXPORT_SYMBOL_GPL(pci_user_read_config_##size);

/* Returns 0 on success, negative values indicate error. */
#define PCI_USER_WRITE_CONFIG(size, type)                               \
int pci_user_write_config_##size                                        \
        (struct pci_dev *dev, int pos, type val)                        \
{                                                                       \
        int ret = PCIBIOS_SUCCESSFUL;                                   \
        if (PCI_##size##_BAD)                                           \
                return -EINVAL;                                         \
        raw_spin_lock_irq(&pci_lock);                           \
        if (unlikely(dev->block_cfg_access))                            \
                pci_wait_cfg(dev);                                      \
        ret = dev->bus->ops->write(dev->bus, dev->devfn,                \
                                        pos, sizeof(type), val);        \
        raw_spin_unlock_irq(&pci_lock);                         \
        return pcibios_err_to_errno(ret);                               \
}                                                                       \
EXPORT_SYMBOL_GPL(pci_user_write_config_##size);

PCI_USER_READ_CONFIG(byte, u8)
PCI_USER_READ_CONFIG(word, u16)
PCI_USER_READ_CONFIG(dword, u32)
PCI_USER_WRITE_CONFIG(byte, u8)
PCI_USER_WRITE_CONFIG(word, u16)
PCI_USER_WRITE_CONFIG(dword, u32)

/**
 * pci_cfg_access_lock - Lock PCI config reads/writes
 * @dev:        pci device struct
 *
 * When access is locked, any userspace reads or writes to config
 * space and concurrent lock requests will sleep until access is
 * allowed via pci_cfg_access_unlock() again.
 */
void pci_cfg_access_lock(struct pci_dev *dev)
{
        might_sleep();

        raw_spin_lock_irq(&pci_lock);
        if (dev->block_cfg_access)
                pci_wait_cfg(dev);
        dev->block_cfg_access = 1;
        raw_spin_unlock_irq(&pci_lock);
}
EXPORT_SYMBOL_GPL(pci_cfg_access_lock);

/**
 * pci_cfg_access_trylock - try to lock PCI config reads/writes
 * @dev:        pci device struct
 *
 * Same as pci_cfg_access_lock, but will return 0 if access is
 * already locked, 1 otherwise. This function can be used from
 * atomic contexts.
 */
bool pci_cfg_access_trylock(struct pci_dev *dev)
{
        unsigned long flags;
        bool locked = true;

        raw_spin_lock_irqsave(&pci_lock, flags);
        if (dev->block_cfg_access)
                locked = false;
        else
                dev->block_cfg_access = 1;
        raw_spin_unlock_irqrestore(&pci_lock, flags);

        return locked;
}
EXPORT_SYMBOL_GPL(pci_cfg_access_trylock);

/**
 * pci_cfg_access_unlock - Unlock PCI config reads/writes
 * @dev:        pci device struct
 *
 * This function allows PCI config accesses to resume.
 */
void pci_cfg_access_unlock(struct pci_dev *dev)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&pci_lock, flags);

        /*
         * This indicates a problem in the caller, but we don't need
         * to kill them, unlike a double-block above.
         */
        WARN_ON(!dev->block_cfg_access);

        dev->block_cfg_access = 0;
        raw_spin_unlock_irqrestore(&pci_lock, flags);

        wake_up_all(&pci_cfg_wait);
}
EXPORT_SYMBOL_GPL(pci_cfg_access_unlock);

static inline int pcie_cap_version(const struct pci_dev *dev)
{
        return pcie_caps_reg(dev) & PCI_EXP_FLAGS_VERS;
}

bool pcie_cap_has_lnkctl(const struct pci_dev *dev)
{
        int type = pci_pcie_type(dev);

        return type == PCI_EXP_TYPE_ENDPOINT ||
               type == PCI_EXP_TYPE_LEG_END ||
               type == PCI_EXP_TYPE_ROOT_PORT ||
               type == PCI_EXP_TYPE_UPSTREAM ||
               type == PCI_EXP_TYPE_DOWNSTREAM ||
               type == PCI_EXP_TYPE_PCI_BRIDGE ||
               type == PCI_EXP_TYPE_PCIE_BRIDGE;
}

static inline bool pcie_cap_has_sltctl(const struct pci_dev *dev)
{
        return pcie_downstream_port(dev) &&
               pcie_caps_reg(dev) & PCI_EXP_FLAGS_SLOT;
}

bool pcie_cap_has_rtctl(const struct pci_dev *dev)
{
        int type = pci_pcie_type(dev);

        return type == PCI_EXP_TYPE_ROOT_PORT ||
               type == PCI_EXP_TYPE_RC_EC;
}

static bool pcie_capability_reg_implemented(struct pci_dev *dev, int pos)
{
        if (!pci_is_pcie(dev))
                return false;

        switch (pos) {
        case PCI_EXP_FLAGS:
                return true;
        case PCI_EXP_DEVCAP:
        case PCI_EXP_DEVCTL:
        case PCI_EXP_DEVSTA:
                return true;
        case PCI_EXP_LNKCAP:
        case PCI_EXP_LNKCTL:
        case PCI_EXP_LNKSTA:
                return pcie_cap_has_lnkctl(dev);
        case PCI_EXP_SLTCAP:
        case PCI_EXP_SLTCTL:
        case PCI_EXP_SLTSTA:
                return pcie_cap_has_sltctl(dev);
        case PCI_EXP_RTCTL:
        case PCI_EXP_RTCAP:
        case PCI_EXP_RTSTA:
                return pcie_cap_has_rtctl(dev);
        case PCI_EXP_DEVCAP2:
        case PCI_EXP_DEVCTL2:
        case PCI_EXP_LNKCAP2:
        case PCI_EXP_LNKCTL2:
        case PCI_EXP_LNKSTA2:
                return pcie_cap_version(dev) > 1;
        default:
                return false;
        }
}

/*
 * Note that these accessor functions are only for the "PCI Express
 * Capability" (see PCIe spec r3.0, sec 7.8).  They do not apply to the
 * other "PCI Express Extended Capabilities" (AER, VC, ACS, MFVC, etc.)
 */
int pcie_capability_read_word(struct pci_dev *dev, int pos, u16 *val)
{
        int ret;

        *val = 0;
        if (pos & 1)
                return PCIBIOS_BAD_REGISTER_NUMBER;

        if (pcie_capability_reg_implemented(dev, pos)) {
                ret = pci_read_config_word(dev, pci_pcie_cap(dev) + pos, val);
                /*
                 * Reset *val to 0 if pci_read_config_word() fails, it may
                 * have been written as 0xFFFF if hardware error happens
                 * during pci_read_config_word().
                 */
                if (ret)
                        *val = 0;
                return ret;
        }

        /*
         * For Functions that do not implement the Slot Capabilities,
         * Slot Status, and Slot Control registers, these spaces must
         * be hardwired to 0b, with the exception of the Presence Detect
         * State bit in the Slot Status register of Downstream Ports,
         * which must be hardwired to 1b.  (PCIe Base Spec 3.0, sec 7.8)
         */
        if (pci_is_pcie(dev) && pcie_downstream_port(dev) &&
            pos == PCI_EXP_SLTSTA)
                *val = PCI_EXP_SLTSTA_PDS;

        return 0;
}
EXPORT_SYMBOL(pcie_capability_read_word);

int pcie_capability_read_dword(struct pci_dev *dev, int pos, u32 *val)
{
        int ret;

        *val = 0;
        if (pos & 3)
                return PCIBIOS_BAD_REGISTER_NUMBER;

        if (pcie_capability_reg_implemented(dev, pos)) {
                ret = pci_read_config_dword(dev, pci_pcie_cap(dev) + pos, val);
                /*
                 * Reset *val to 0 if pci_read_config_dword() fails, it may
                 * have been written as 0xFFFFFFFF if hardware error happens
                 * during pci_read_config_dword().
                 */
                if (ret)
                        *val = 0;
                return ret;
        }

        if (pci_is_pcie(dev) && pcie_downstream_port(dev) &&
            pos == PCI_EXP_SLTSTA)
                *val = PCI_EXP_SLTSTA_PDS;

        return 0;
}
EXPORT_SYMBOL(pcie_capability_read_dword);

int pcie_capability_write_word(struct pci_dev *dev, int pos, u16 val)
{
        if (pos & 1)
                return PCIBIOS_BAD_REGISTER_NUMBER;

        if (!pcie_capability_reg_implemented(dev, pos))
                return 0;

        return pci_write_config_word(dev, pci_pcie_cap(dev) + pos, val);
}
EXPORT_SYMBOL(pcie_capability_write_word);

int pcie_capability_write_dword(struct pci_dev *dev, int pos, u32 val)
{
        if (pos & 3)
                return PCIBIOS_BAD_REGISTER_NUMBER;

        if (!pcie_capability_reg_implemented(dev, pos))
                return 0;

        return pci_write_config_dword(dev, pci_pcie_cap(dev) + pos, val);
}
EXPORT_SYMBOL(pcie_capability_write_dword);

int pcie_capability_clear_and_set_word(struct pci_dev *dev, int pos,
                                       u16 clear, u16 set)
{
        int ret;
        u16 val;

        ret = pcie_capability_read_word(dev, pos, &val);
        if (!ret) {
                val &= ~clear;
                val |= set;
                ret = pcie_capability_write_word(dev, pos, val);
        }

        return ret;
}
EXPORT_SYMBOL(pcie_capability_clear_and_set_word);

int pcie_capability_clear_and_set_dword(struct pci_dev *dev, int pos,
                                        u32 clear, u32 set)
{
        int ret;
        u32 val;

        ret = pcie_capability_read_dword(dev, pos, &val);
        if (!ret) {
                val &= ~clear;
                val |= set;
                ret = pcie_capability_write_dword(dev, pos, val);
        }

        return ret;
}
EXPORT_SYMBOL(pcie_capability_clear_and_set_dword);

int pci_read_config_byte(const struct pci_dev *dev, int where, u8 *val)
{
        if (pci_dev_is_disconnected(dev)) {
                *val = ~0;
                return PCIBIOS_DEVICE_NOT_FOUND;
        }
        return pci_bus_read_config_byte(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_read_config_byte);

int pci_read_config_word(const struct pci_dev *dev, int where, u16 *val)
{
        if (pci_dev_is_disconnected(dev)) {
                *val = ~0;
                return PCIBIOS_DEVICE_NOT_FOUND;
        }
        return pci_bus_read_config_word(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_read_config_word);

int pci_read_config_dword(const struct pci_dev *dev, int where,
                                        u32 *val)
{
        if (pci_dev_is_disconnected(dev)) {
                *val = ~0;
                return PCIBIOS_DEVICE_NOT_FOUND;
        }
        return pci_bus_read_config_dword(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_read_config_dword);

int pci_write_config_byte(const struct pci_dev *dev, int where, u8 val)
{
        if (pci_dev_is_disconnected(dev))
                return PCIBIOS_DEVICE_NOT_FOUND;
        return pci_bus_write_config_byte(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_write_config_byte);

int pci_write_config_word(const struct pci_dev *dev, int where, u16 val)
{
        if (pci_dev_is_disconnected(dev))
                return PCIBIOS_DEVICE_NOT_FOUND;
        return pci_bus_write_config_word(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_write_config_word);

int pci_write_config_dword(const struct pci_dev *dev, int where,
                                         u32 val)
{
        if (pci_dev_is_disconnected(dev))
                return PCIBIOS_DEVICE_NOT_FOUND;
        return pci_bus_write_config_dword(dev->bus, dev->devfn, where, val);
}
EXPORT_SYMBOL(pci_write_config_dword);