#include <linux/delay.h>
#include <linux/pci.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/wait.h>

#include "pci.h"

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

static DEFINE_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)

#define PCI_OP_READ(size,type,len) \
int 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;       \
        spin_lock_irqsave(&pci_lock, flags);                            \
        res = bus->ops->read(bus, devfn, pos, len, &data);              \
        *value = (type)data;                                            \
        spin_unlock_irqrestore(&pci_lock, flags);                       \
        return res;                                                     \
}

#define PCI_OP_WRITE(size,type,len) \
int 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;       \
        spin_lock_irqsave(&pci_lock, flags);                            \
        res = bus->ops->write(bus, devfn, pos, len, value);             \
        spin_unlock_irqrestore(&pci_lock, 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);


/**
 * pci_read_vpd - Read one entry from Vital Product Data
 * @dev:        pci device struct
 * @pos:        offset in vpd space
 * @count:      number of bytes to read
 * @buf:        pointer to where to store result
 *
 */
ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf)
{
        if (!dev->vpd || !dev->vpd->ops)
                return -ENODEV;
        return dev->vpd->ops->read(dev, pos, count, buf);
}
EXPORT_SYMBOL(pci_read_vpd);

/**
 * pci_write_vpd - Write entry to Vital Product Data
 * @dev:        pci device struct
 * @pos:        offset in vpd space
 * @count:      number of bytes to write
 * @buf:        buffer containing write data
 *
 */
ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf)
{
        if (!dev->vpd || !dev->vpd->ops)
                return -ENODEV;
        return dev->vpd->ops->write(dev, pos, count, buf);
}
EXPORT_SYMBOL(pci_write_vpd);

/*
 * 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_ucfg_wait);

static noinline void pci_wait_ucfg(struct pci_dev *dev)
{
        DECLARE_WAITQUEUE(wait, current);

        __add_wait_queue(&pci_ucfg_wait, &wait);
        do {
                set_current_state(TASK_UNINTERRUPTIBLE);
                spin_unlock_irq(&pci_lock);
                schedule();
                spin_lock_irq(&pci_lock);
        } while (dev->block_ucfg_access);
        __remove_wait_queue(&pci_ucfg_wait, &wait);
}

#define PCI_USER_READ_CONFIG(size,type)                                 \
int pci_user_read_config_##size                                         \
        (struct pci_dev *dev, int pos, type *val)                       \
{                                                                       \
        int ret = 0;                                                    \
        u32 data = -1;                                                  \
        if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
        spin_lock_irq(&pci_lock);                                       \
        if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev);       \
        ret = dev->bus->ops->read(dev->bus, dev->devfn,                 \
                                        pos, sizeof(type), &data);      \
        spin_unlock_irq(&pci_lock);                                     \
        *val = (type)data;                                              \
        return ret;                                                     \
}

#define PCI_USER_WRITE_CONFIG(size,type)                                \
int pci_user_write_config_##size                                        \
        (struct pci_dev *dev, int pos, type val)                        \
{                                                                       \
        int ret = -EIO;                                                 \
        if (PCI_##size##_BAD) return PCIBIOS_BAD_REGISTER_NUMBER;       \
        spin_lock_irq(&pci_lock);                                       \
        if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev);       \
        ret = dev->bus->ops->write(dev->bus, dev->devfn,                \
                                        pos, sizeof(type), val);        \
        spin_unlock_irq(&pci_lock);                                     \
        return ret;                                                     \
}

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)

/* VPD access through PCI 2.2+ VPD capability */

#define PCI_VPD_PCI22_SIZE (PCI_VPD_ADDR_MASK + 1)

struct pci_vpd_pci22 {
        struct pci_vpd base;
        struct mutex lock;
        u16     flag;
        bool    busy;
        u8      cap;
};

/*
 * Wait for last operation to complete.
 * This code has to spin since there is no other notification from the PCI
 * hardware. Since the VPD is often implemented by serial attachment to an
 * EEPROM, it may take many milliseconds to complete.
 */
static int pci_vpd_pci22_wait(struct pci_dev *dev)
{
        struct pci_vpd_pci22 *vpd =
                container_of(dev->vpd, struct pci_vpd_pci22, base);
        unsigned long timeout = jiffies + HZ/20 + 2;
        u16 status;
        int ret;

        if (!vpd->busy)
                return 0;

        for (;;) {
                ret = pci_user_read_config_word(dev, vpd->cap + PCI_VPD_ADDR,
                                                &status);
                if (ret)
                        return ret;

                if ((status & PCI_VPD_ADDR_F) == vpd->flag) {
                        vpd->busy = false;
                        return 0;
                }

                if (time_after(jiffies, timeout))
                        return -ETIMEDOUT;
                if (fatal_signal_pending(current))
                        return -EINTR;
                if (!cond_resched())
                        udelay(10);
        }
}

static ssize_t pci_vpd_pci22_read(struct pci_dev *dev, loff_t pos, size_t count,
                                  void *arg)
{
        struct pci_vpd_pci22 *vpd =
                container_of(dev->vpd, struct pci_vpd_pci22, base);
        int ret;
        loff_t end = pos + count;
        u8 *buf = arg;

        if (pos < 0 || pos > vpd->base.len || end > vpd->base.len)
                return -EINVAL;

        if (mutex_lock_killable(&vpd->lock))
                return -EINTR;

        ret = pci_vpd_pci22_wait(dev);
        if (ret < 0)
                goto out;

        while (pos < end) {
                u32 val;
                unsigned int i, skip;

                ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
                                                 pos & ~3);
                if (ret < 0)
                        break;
                vpd->busy = true;
                vpd->flag = PCI_VPD_ADDR_F;
                ret = pci_vpd_pci22_wait(dev);
                if (ret < 0)
                        break;

                ret = pci_user_read_config_dword(dev, vpd->cap + PCI_VPD_DATA, &val);
                if (ret < 0)
                        break;

                skip = pos & 3;
                for (i = 0;  i < sizeof(u32); i++) {
                        if (i >= skip) {
                                *buf++ = val;
                                if (++pos == end)
                                        break;
                        }
                        val >>= 8;
                }
        }
out:
        mutex_unlock(&vpd->lock);
        return ret ? ret : count;
}

static ssize_t pci_vpd_pci22_write(struct pci_dev *dev, loff_t pos, size_t count,
                                   const void *arg)
{
        struct pci_vpd_pci22 *vpd =
                container_of(dev->vpd, struct pci_vpd_pci22, base);
        const u8 *buf = arg;
        loff_t end = pos + count;
        int ret = 0;

        if (pos < 0 || (pos & 3) || (count & 3) || end > vpd->base.len)
                return -EINVAL;

        if (mutex_lock_killable(&vpd->lock))
                return -EINTR;

        ret = pci_vpd_pci22_wait(dev);
        if (ret < 0)
                goto out;

        while (pos < end) {
                u32 val;

                val = *buf++;
                val |= *buf++ << 8;
                val |= *buf++ << 16;
                val |= *buf++ << 24;

                ret = pci_user_write_config_dword(dev, vpd->cap + PCI_VPD_DATA, val);
                if (ret < 0)
                        break;
                ret = pci_user_write_config_word(dev, vpd->cap + PCI_VPD_ADDR,
                                                 pos | PCI_VPD_ADDR_F);
                if (ret < 0)
                        break;

                vpd->busy = true;
                vpd->flag = 0;
                ret = pci_vpd_pci22_wait(dev);

                pos += sizeof(u32);
        }
out:
        mutex_unlock(&vpd->lock);
        return ret ? ret : count;
}

static void pci_vpd_pci22_release(struct pci_dev *dev)
{
        kfree(container_of(dev->vpd, struct pci_vpd_pci22, base));
}

static const struct pci_vpd_ops pci_vpd_pci22_ops = {
        .read = pci_vpd_pci22_read,
        .write = pci_vpd_pci22_write,
        .release = pci_vpd_pci22_release,
};

int pci_vpd_pci22_init(struct pci_dev *dev)
{
        struct pci_vpd_pci22 *vpd;
        u8 cap;

        cap = pci_find_capability(dev, PCI_CAP_ID_VPD);
        if (!cap)
                return -ENODEV;
        vpd = kzalloc(sizeof(*vpd), GFP_ATOMIC);
        if (!vpd)
                return -ENOMEM;

        vpd->base.len = PCI_VPD_PCI22_SIZE;
        vpd->base.ops = &pci_vpd_pci22_ops;
        mutex_init(&vpd->lock);
        vpd->cap = cap;
        vpd->busy = false;
        dev->vpd = &vpd->base;
        return 0;
}

/**
 * pci_vpd_truncate - Set available Vital Product Data size
 * @dev:        pci device struct
 * @size:       available memory in bytes
 *
 * Adjust size of available VPD area.
 */
int pci_vpd_truncate(struct pci_dev *dev, size_t size)
{
        if (!dev->vpd)
                return -EINVAL;

        /* limited by the access method */
        if (size > dev->vpd->len)
                return -EINVAL;

        dev->vpd->len = size;
        if (dev->vpd->attr)
                dev->vpd->attr->size = size;

        return 0;
}
EXPORT_SYMBOL(pci_vpd_truncate);

/**
 * pci_block_user_cfg_access - Block userspace PCI config reads/writes
 * @dev:        pci device struct
 *
 * When user access is blocked, any reads or writes to config space will
 * sleep until access is unblocked again.  We don't allow nesting of
 * block/unblock calls.
 */
void pci_block_user_cfg_access(struct pci_dev *dev)
{
        unsigned long flags;
        int was_blocked;

        spin_lock_irqsave(&pci_lock, flags);
        was_blocked = dev->block_ucfg_access;
        dev->block_ucfg_access = 1;
        spin_unlock_irqrestore(&pci_lock, flags);

        /* If we BUG() inside the pci_lock, we're guaranteed to hose
         * the machine */
        BUG_ON(was_blocked);
}
EXPORT_SYMBOL_GPL(pci_block_user_cfg_access);

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

        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_ucfg_access);

        dev->block_ucfg_access = 0;
        wake_up_all(&pci_ucfg_wait);
        spin_unlock_irqrestore(&pci_lock, flags);
}
EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access);