/*
   * File:	msi.c
   * Purpose:	PCI Message Signaled Interrupt (MSI)
   *
   * Copyright (C) 2003-2004 Intel
   * Copyright (C) Tom Long Nguyen (tom.l.nguyen@intel.com)
   */

  #include <linux/err.h>

  #include <linux/mm.h>
  #include <linux/irq.h>
  #include <linux/interrupt.h>
  #include <linux/init.h>

  #include <linux/export.h>

  #include <linux/ioport.h>

  #include <linux/pci.h>
  #include <linux/proc_fs.h>

  #include <linux/msi.h>

  #include <linux/smp.h>

  #include <linux/errno.h>
  #include <linux/io.h>

  #include <linux/slab.h>

  
  #include "pci.h"
  #include "msi.h"

  static int pci_msi_enable = 1;

  /* Arch hooks */

  #ifndef arch_msi_check_device
  int arch_msi_check_device(struct pci_dev *dev, int nvec, int type)

  {
  	return 0;
  }

  #endif

  #ifndef arch_setup_msi_irqs

  # define arch_setup_msi_irqs default_setup_msi_irqs
  # define HAVE_DEFAULT_MSI_SETUP_IRQS
  #endif
  
  #ifdef HAVE_DEFAULT_MSI_SETUP_IRQS
  int default_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)

  {
  	struct msi_desc *entry;
  	int ret;

  	/*
  	 * If an architecture wants to support multiple MSI, it needs to
  	 * override arch_setup_msi_irqs()
  	 */
  	if (type == PCI_CAP_ID_MSI && nvec > 1)
  		return 1;

  	list_for_each_entry(entry, &dev->msi_list, list) {
  		ret = arch_setup_msi_irq(dev, entry);

  		if (ret < 0)

  			return ret;

  		if (ret > 0)
  			return -ENOSPC;

  	}
  
  	return 0;
  }

  #endif

  #ifndef arch_teardown_msi_irqs

  # define arch_teardown_msi_irqs default_teardown_msi_irqs
  # define HAVE_DEFAULT_MSI_TEARDOWN_IRQS
  #endif
  
  #ifdef HAVE_DEFAULT_MSI_TEARDOWN_IRQS
  void default_teardown_msi_irqs(struct pci_dev *dev)

  {
  	struct msi_desc *entry;
  
  	list_for_each_entry(entry, &dev->msi_list, list) {

  		int i, nvec;
  		if (entry->irq == 0)
  			continue;
  		nvec = 1 << entry->msi_attrib.multiple;
  		for (i = 0; i < nvec; i++)
  			arch_teardown_msi_irq(entry->irq + i);

  	}
  }

  #endif

  #ifndef arch_restore_msi_irqs
  # define arch_restore_msi_irqs default_restore_msi_irqs
  # define HAVE_DEFAULT_MSI_RESTORE_IRQS
  #endif
  
  #ifdef HAVE_DEFAULT_MSI_RESTORE_IRQS
  void default_restore_msi_irqs(struct pci_dev *dev, int irq)
  {
  	struct msi_desc *entry;
  
  	entry = NULL;
  	if (dev->msix_enabled) {
  		list_for_each_entry(entry, &dev->msi_list, list) {
  			if (irq == entry->irq)
  				break;
  		}
  	} else if (dev->msi_enabled)  {
  		entry = irq_get_msi_desc(irq);
  	}
  
  	if (entry)
  		write_msi_msg(irq, &entry->msg);
  }
  #endif

  static void msi_set_enable(struct pci_dev *dev, int pos, int enable)

  {

  	u16 control;

  	BUG_ON(!pos);

  	pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &control);
  	control &= ~PCI_MSI_FLAGS_ENABLE;
  	if (enable)
  		control |= PCI_MSI_FLAGS_ENABLE;
  	pci_write_config_word(dev, pos + PCI_MSI_FLAGS, control);

  }

  static void msix_set_enable(struct pci_dev *dev, int enable)
  {
  	int pos;
  	u16 control;
  
  	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
  	if (pos) {
  		pci_read_config_word(dev, pos + PCI_MSIX_FLAGS, &control);
  		control &= ~PCI_MSIX_FLAGS_ENABLE;
  		if (enable)
  			control |= PCI_MSIX_FLAGS_ENABLE;
  		pci_write_config_word(dev, pos + PCI_MSIX_FLAGS, control);
  	}
  }

  static inline __attribute_const__ u32 msi_mask(unsigned x)
  {

  	/* Don't shift by >= width of type */
  	if (x >= 5)
  		return 0xffffffff;
  	return (1 << (1 << x)) - 1;

  }

  static inline __attribute_const__ u32 msi_capable_mask(u16 control)

  {

  	return msi_mask((control >> 1) & 7);
  }

  static inline __attribute_const__ u32 msi_enabled_mask(u16 control)
  {
  	return msi_mask((control >> 4) & 7);

  }

  /*
   * PCI 2.3 does not specify mask bits for each MSI interrupt.  Attempting to
   * mask all MSI interrupts by clearing the MSI enable bit does not work
   * reliably as devices without an INTx disable bit will then generate a
   * level IRQ which will never be cleared.

   */

  static u32 __msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)

  {

  	u32 mask_bits = desc->masked;

  	if (!desc->msi_attrib.maskbit)

  		return 0;

  
  	mask_bits &= ~mask;
  	mask_bits |= flag;
  	pci_write_config_dword(desc->dev, desc->mask_pos, mask_bits);

  
  	return mask_bits;
  }
  
  static void msi_mask_irq(struct msi_desc *desc, u32 mask, u32 flag)
  {
  	desc->masked = __msi_mask_irq(desc, mask, flag);

  }
  
  /*
   * This internal function does not flush PCI writes to the device.
   * All users must ensure that they read from the device before either
   * assuming that the device state is up to date, or returning out of this
   * file.  This saves a few milliseconds when initialising devices with lots
   * of MSI-X interrupts.
   */

  static u32 __msix_mask_irq(struct msi_desc *desc, u32 flag)

  {
  	u32 mask_bits = desc->masked;
  	unsigned offset = desc->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE +

  						PCI_MSIX_ENTRY_VECTOR_CTRL;

  	mask_bits &= ~PCI_MSIX_ENTRY_CTRL_MASKBIT;
  	if (flag)
  		mask_bits |= PCI_MSIX_ENTRY_CTRL_MASKBIT;

  	writel(mask_bits, desc->mask_base + offset);

  
  	return mask_bits;
  }
  
  static void msix_mask_irq(struct msi_desc *desc, u32 flag)
  {
  	desc->masked = __msix_mask_irq(desc, flag);

  }

  static void msi_set_mask_bit(struct irq_data *data, u32 flag)

  {

  	struct msi_desc *desc = irq_data_get_msi(data);

  	if (desc->msi_attrib.is_msix) {
  		msix_mask_irq(desc, flag);
  		readl(desc->mask_base);		/* Flush write to device */
  	} else {

  		unsigned offset = data->irq - desc->dev->irq;

  		msi_mask_irq(desc, 1 << offset, flag << offset);

  	}

  }

  void mask_msi_irq(struct irq_data *data)

  {

  	msi_set_mask_bit(data, 1);

  }

  void unmask_msi_irq(struct irq_data *data)

  {

  	msi_set_mask_bit(data, 0);

  }

  void __read_msi_msg(struct msi_desc *entry, struct msi_msg *msg)

  {

  	BUG_ON(entry->dev->current_state != PCI_D0);
  
  	if (entry->msi_attrib.is_msix) {
  		void __iomem *base = entry->mask_base +
  			entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;
  
  		msg->address_lo = readl(base + PCI_MSIX_ENTRY_LOWER_ADDR);
  		msg->address_hi = readl(base + PCI_MSIX_ENTRY_UPPER_ADDR);
  		msg->data = readl(base + PCI_MSIX_ENTRY_DATA);
  	} else {
  		struct pci_dev *dev = entry->dev;
  		int pos = entry->msi_attrib.pos;
  		u16 data;
  
  		pci_read_config_dword(dev, msi_lower_address_reg(pos),
  					&msg->address_lo);
  		if (entry->msi_attrib.is_64) {
  			pci_read_config_dword(dev, msi_upper_address_reg(pos),
  						&msg->address_hi);
  			pci_read_config_word(dev, msi_data_reg(pos, 1), &data);
  		} else {
  			msg->address_hi = 0;
  			pci_read_config_word(dev, msi_data_reg(pos, 0), &data);
  		}
  		msg->data = data;
  	}
  }
  
  void read_msi_msg(unsigned int irq, struct msi_msg *msg)
  {

  	struct msi_desc *entry = irq_get_msi_desc(irq);

  	__read_msi_msg(entry, msg);

  }

  void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg)

  {

  	/* Assert that the cache is valid, assuming that

  	 * valid messages are not all-zeroes. */
  	BUG_ON(!(entry->msg.address_hi | entry->msg.address_lo |
  		 entry->msg.data));

  	*msg = entry->msg;

  }

  void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)

  {

  	struct msi_desc *entry = irq_get_msi_desc(irq);

  	__get_cached_msi_msg(entry, msg);

  }

  void __write_msi_msg(struct msi_desc *entry, struct msi_msg *msg)

  {

  	if (entry->dev->current_state != PCI_D0) {
  		/* Don't touch the hardware now */
  	} else if (entry->msi_attrib.is_msix) {

  		void __iomem *base;
  		base = entry->mask_base +
  			entry->msi_attrib.entry_nr * PCI_MSIX_ENTRY_SIZE;

  		writel(msg->address_lo, base + PCI_MSIX_ENTRY_LOWER_ADDR);
  		writel(msg->address_hi, base + PCI_MSIX_ENTRY_UPPER_ADDR);
  		writel(msg->data, base + PCI_MSIX_ENTRY_DATA);

  	} else {

  		struct pci_dev *dev = entry->dev;
  		int pos = entry->msi_attrib.pos;

  		u16 msgctl;
  
  		pci_read_config_word(dev, msi_control_reg(pos), &msgctl);
  		msgctl &= ~PCI_MSI_FLAGS_QSIZE;
  		msgctl |= entry->msi_attrib.multiple << 4;
  		pci_write_config_word(dev, msi_control_reg(pos), msgctl);

  
  		pci_write_config_dword(dev, msi_lower_address_reg(pos),
  					msg->address_lo);
  		if (entry->msi_attrib.is_64) {
  			pci_write_config_dword(dev, msi_upper_address_reg(pos),
  						msg->address_hi);
  			pci_write_config_word(dev, msi_data_reg(pos, 1),
  						msg->data);
  		} else {
  			pci_write_config_word(dev, msi_data_reg(pos, 0),
  						msg->data);
  		}

  	}

  	entry->msg = *msg;

  }

  void write_msi_msg(unsigned int irq, struct msi_msg *msg)
  {

  	struct msi_desc *entry = irq_get_msi_desc(irq);

  	__write_msi_msg(entry, msg);

  }

  static void free_msi_irqs(struct pci_dev *dev)
  {
  	struct msi_desc *entry, *tmp;
  
  	list_for_each_entry(entry, &dev->msi_list, list) {
  		int i, nvec;
  		if (!entry->irq)
  			continue;
  		nvec = 1 << entry->msi_attrib.multiple;
  		for (i = 0; i < nvec; i++)
  			BUG_ON(irq_has_action(entry->irq + i));
  	}
  
  	arch_teardown_msi_irqs(dev);
  
  	list_for_each_entry_safe(entry, tmp, &dev->msi_list, list) {
  		if (entry->msi_attrib.is_msix) {
  			if (list_is_last(&entry->list, &dev->msi_list))
  				iounmap(entry->mask_base);
  		}

  
  		/*
  		 * Its possible that we get into this path
  		 * When populate_msi_sysfs fails, which means the entries
  		 * were not registered with sysfs.  In that case don't
  		 * unregister them.
  		 */
  		if (entry->kobj.parent) {
  			kobject_del(&entry->kobj);
  			kobject_put(&entry->kobj);
  		}

  		list_del(&entry->list);
  		kfree(entry);
  	}
  }

  static struct msi_desc *alloc_msi_entry(struct pci_dev *dev)

  {

  	struct msi_desc *desc = kzalloc(sizeof(*desc), GFP_KERNEL);
  	if (!desc)

  		return NULL;

  	INIT_LIST_HEAD(&desc->list);
  	desc->dev = dev;

  	return desc;

  }

  static void pci_intx_for_msi(struct pci_dev *dev, int enable)
  {
  	if (!(dev->dev_flags & PCI_DEV_FLAGS_MSI_INTX_DISABLE_BUG))
  		pci_intx(dev, enable);
  }

  static void __pci_restore_msi_state(struct pci_dev *dev)

  {

  	int pos;

  	u16 control;

  	struct msi_desc *entry;

  	if (!dev->msi_enabled)
  		return;

  	entry = irq_get_msi_desc(dev->irq);

  	pos = entry->msi_attrib.pos;

  	pci_intx_for_msi(dev, 0);

  	msi_set_enable(dev, pos, 0);

  	arch_restore_msi_irqs(dev, dev->irq);

  
  	pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &control);

  	msi_mask_irq(entry, msi_capable_mask(control), entry->masked);

  	control &= ~PCI_MSI_FLAGS_QSIZE;

  	control |= (entry->msi_attrib.multiple << 4) | PCI_MSI_FLAGS_ENABLE;

  	pci_write_config_word(dev, pos + PCI_MSI_FLAGS, control);

  }
  
  static void __pci_restore_msix_state(struct pci_dev *dev)

  {

  	int pos;

  	struct msi_desc *entry;

  	u16 control;

  	if (!dev->msix_enabled)
  		return;

  	BUG_ON(list_empty(&dev->msi_list));

  	entry = list_first_entry(&dev->msi_list, struct msi_desc, list);

  	pos = entry->msi_attrib.pos;
  	pci_read_config_word(dev, pos + PCI_MSIX_FLAGS, &control);

  	/* route the table */

  	pci_intx_for_msi(dev, 0);

  	control |= PCI_MSIX_FLAGS_ENABLE | PCI_MSIX_FLAGS_MASKALL;
  	pci_write_config_word(dev, pos + PCI_MSIX_FLAGS, control);

  	list_for_each_entry(entry, &dev->msi_list, list) {

  		arch_restore_msi_irqs(dev, entry->irq);

  		msix_mask_irq(entry, entry->masked);

  	}

  	control &= ~PCI_MSIX_FLAGS_MASKALL;

  	pci_write_config_word(dev, pos + PCI_MSIX_FLAGS, control);

  }

  
  void pci_restore_msi_state(struct pci_dev *dev)
  {
  	__pci_restore_msi_state(dev);
  	__pci_restore_msix_state(dev);
  }

  EXPORT_SYMBOL_GPL(pci_restore_msi_state);

  
  #define to_msi_attr(obj) container_of(obj, struct msi_attribute, attr)
  #define to_msi_desc(obj) container_of(obj, struct msi_desc, kobj)
  
  struct msi_attribute {
  	struct attribute        attr;
  	ssize_t (*show)(struct msi_desc *entry, struct msi_attribute *attr,
  			char *buf);
  	ssize_t (*store)(struct msi_desc *entry, struct msi_attribute *attr,
  			 const char *buf, size_t count);
  };
  
  static ssize_t show_msi_mode(struct msi_desc *entry, struct msi_attribute *atr,
  			     char *buf)
  {
  	return sprintf(buf, "%s
  ", entry->msi_attrib.is_msix ? "msix" : "msi");
  }
  
  static ssize_t msi_irq_attr_show(struct kobject *kobj,
  				 struct attribute *attr, char *buf)
  {
  	struct msi_attribute *attribute = to_msi_attr(attr);
  	struct msi_desc *entry = to_msi_desc(kobj);
  
  	if (!attribute->show)
  		return -EIO;
  
  	return attribute->show(entry, attribute, buf);
  }
  
  static const struct sysfs_ops msi_irq_sysfs_ops = {
  	.show = msi_irq_attr_show,
  };
  
  static struct msi_attribute mode_attribute =
  	__ATTR(mode, S_IRUGO, show_msi_mode, NULL);
  
  
  struct attribute *msi_irq_default_attrs[] = {
  	&mode_attribute.attr,
  	NULL
  };
  
  void msi_kobj_release(struct kobject *kobj)
  {
  	struct msi_desc *entry = to_msi_desc(kobj);
  
  	pci_dev_put(entry->dev);
  }
  
  static struct kobj_type msi_irq_ktype = {
  	.release = msi_kobj_release,
  	.sysfs_ops = &msi_irq_sysfs_ops,
  	.default_attrs = msi_irq_default_attrs,
  };
  
  static int populate_msi_sysfs(struct pci_dev *pdev)
  {
  	struct msi_desc *entry;
  	struct kobject *kobj;
  	int ret;
  	int count = 0;
  
  	pdev->msi_kset = kset_create_and_add("msi_irqs", NULL, &pdev->dev.kobj);
  	if (!pdev->msi_kset)
  		return -ENOMEM;
  
  	list_for_each_entry(entry, &pdev->msi_list, list) {
  		kobj = &entry->kobj;
  		kobj->kset = pdev->msi_kset;
  		pci_dev_get(pdev);
  		ret = kobject_init_and_add(kobj, &msi_irq_ktype, NULL,
  				     "%u", entry->irq);
  		if (ret)
  			goto out_unroll;
  
  		count++;
  	}
  
  	return 0;
  
  out_unroll:
  	list_for_each_entry(entry, &pdev->msi_list, list) {
  		if (!count)
  			break;
  		kobject_del(&entry->kobj);
  		kobject_put(&entry->kobj);
  		count--;
  	}
  	return ret;
  }

  /**
   * msi_capability_init - configure device's MSI capability structure
   * @dev: pointer to the pci_dev data structure of MSI device function

   * @nvec: number of interrupts to allocate

   *

   * Setup the MSI capability structure of the device with the requested
   * number of interrupts.  A return value of zero indicates the successful
   * setup of an entry with the new MSI irq.  A negative return value indicates
   * an error, and a positive return value indicates the number of interrupts
   * which could have been allocated.
   */
  static int msi_capability_init(struct pci_dev *dev, int nvec)

  {
  	struct msi_desc *entry;

  	int pos, ret;

  	u16 control;

  	unsigned mask;

  	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);

  	msi_set_enable(dev, pos, 0);	/* Disable MSI during set up */

  	pci_read_config_word(dev, msi_control_reg(pos), &control);
  	/* MSI Entry Initialization */

  	entry = alloc_msi_entry(dev);

  	if (!entry)
  		return -ENOMEM;

  	entry->msi_attrib.is_msix	= 0;
  	entry->msi_attrib.is_64		= is_64bit_address(control);
  	entry->msi_attrib.entry_nr	= 0;
  	entry->msi_attrib.maskbit	= is_mask_bit_support(control);
  	entry->msi_attrib.default_irq	= dev->irq;	/* Save IOAPIC IRQ */
  	entry->msi_attrib.pos		= pos;

  	entry->mask_pos = msi_mask_reg(pos, entry->msi_attrib.is_64);

  	/* All MSIs are unmasked by default, Mask them all */
  	if (entry->msi_attrib.maskbit)
  		pci_read_config_dword(dev, entry->mask_pos, &entry->masked);
  	mask = msi_capable_mask(control);
  	msi_mask_irq(entry, mask, mask);

  	list_add_tail(&entry->list, &dev->msi_list);

  	/* Configure MSI capability structure */

  	ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);

  	if (ret) {

  		msi_mask_irq(entry, mask, ~mask);

  		free_msi_irqs(dev);

  		return ret;

  	}

  	ret = populate_msi_sysfs(dev);
  	if (ret) {
  		msi_mask_irq(entry, mask, ~mask);
  		free_msi_irqs(dev);
  		return ret;
  	}

  	/* Set MSI enabled bits	 */

  	pci_intx_for_msi(dev, 0);

  	msi_set_enable(dev, pos, 1);

  	dev->msi_enabled = 1;

  	dev->irq = entry->irq;

  	return 0;
  }

  static void __iomem *msix_map_region(struct pci_dev *dev, unsigned pos,
  							unsigned nr_entries)
  {

  	resource_size_t phys_addr;

  	u32 table_offset;
  	u8 bir;
  
  	pci_read_config_dword(dev, msix_table_offset_reg(pos), &table_offset);
  	bir = (u8)(table_offset & PCI_MSIX_FLAGS_BIRMASK);
  	table_offset &= ~PCI_MSIX_FLAGS_BIRMASK;
  	phys_addr = pci_resource_start(dev, bir) + table_offset;
  
  	return ioremap_nocache(phys_addr, nr_entries * PCI_MSIX_ENTRY_SIZE);
  }

  static int msix_setup_entries(struct pci_dev *dev, unsigned pos,
  				void __iomem *base, struct msix_entry *entries,
  				int nvec)
  {
  	struct msi_desc *entry;
  	int i;
  
  	for (i = 0; i < nvec; i++) {
  		entry = alloc_msi_entry(dev);
  		if (!entry) {
  			if (!i)
  				iounmap(base);
  			else
  				free_msi_irqs(dev);
  			/* No enough memory. Don't try again */
  			return -ENOMEM;
  		}
  
  		entry->msi_attrib.is_msix	= 1;
  		entry->msi_attrib.is_64		= 1;
  		entry->msi_attrib.entry_nr	= entries[i].entry;
  		entry->msi_attrib.default_irq	= dev->irq;
  		entry->msi_attrib.pos		= pos;
  		entry->mask_base		= base;
  
  		list_add_tail(&entry->list, &dev->msi_list);
  	}
  
  	return 0;
  }

  static void msix_program_entries(struct pci_dev *dev,
  					struct msix_entry *entries)
  {
  	struct msi_desc *entry;
  	int i = 0;
  
  	list_for_each_entry(entry, &dev->msi_list, list) {
  		int offset = entries[i].entry * PCI_MSIX_ENTRY_SIZE +
  						PCI_MSIX_ENTRY_VECTOR_CTRL;
  
  		entries[i].vector = entry->irq;

  		irq_set_msi_desc(entry->irq, entry);

  		entry->masked = readl(entry->mask_base + offset);
  		msix_mask_irq(entry, 1);
  		i++;
  	}
  }

  /**
   * msix_capability_init - configure device's MSI-X capability
   * @dev: pointer to the pci_dev data structure of MSI-X device function

   * @entries: pointer to an array of struct msix_entry entries
   * @nvec: number of @entries

   *

   * Setup the MSI-X capability structure of device function with a

   * single MSI-X irq. A return of zero indicates the successful setup of
   * requested MSI-X entries with allocated irqs or non-zero for otherwise.

   **/
  static int msix_capability_init(struct pci_dev *dev,
  				struct msix_entry *entries, int nvec)
  {

  	int pos, ret;

  	u16 control;

  	void __iomem *base;

  	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);

  	pci_read_config_word(dev, pos + PCI_MSIX_FLAGS, &control);
  
  	/* Ensure MSI-X is disabled while it is set up */
  	control &= ~PCI_MSIX_FLAGS_ENABLE;
  	pci_write_config_word(dev, pos + PCI_MSIX_FLAGS, control);

  	/* Request & Map MSI-X table region */

  	base = msix_map_region(dev, pos, multi_msix_capable(control));
  	if (!base)

  		return -ENOMEM;

  	ret = msix_setup_entries(dev, pos, base, entries, nvec);
  	if (ret)
  		return ret;

  
  	ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);

  	if (ret)
  		goto error;

  	/*
  	 * Some devices require MSI-X to be enabled before we can touch the
  	 * MSI-X registers.  We need to mask all the vectors to prevent
  	 * interrupts coming in before they're fully set up.
  	 */
  	control |= PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE;
  	pci_write_config_word(dev, pos + PCI_MSIX_FLAGS, control);

  	msix_program_entries(dev, entries);

  	ret = populate_msi_sysfs(dev);
  	if (ret) {
  		ret = 0;
  		goto error;
  	}

  	/* Set MSI-X enabled bits and unmask the function */

  	pci_intx_for_msi(dev, 0);

  	dev->msix_enabled = 1;

  	control &= ~PCI_MSIX_FLAGS_MASKALL;
  	pci_write_config_word(dev, pos + PCI_MSIX_FLAGS, control);

  	return 0;

  
  error:
  	if (ret < 0) {
  		/*
  		 * If we had some success, report the number of irqs
  		 * we succeeded in setting up.
  		 */

  		struct msi_desc *entry;

  		int avail = 0;
  
  		list_for_each_entry(entry, &dev->msi_list, list) {
  			if (entry->irq != 0)
  				avail++;
  		}
  		if (avail != 0)
  			ret = avail;
  	}
  
  	free_msi_irqs(dev);
  
  	return ret;

  }
  
  /**

   * pci_msi_check_device - check whether MSI may be enabled on a device

   * @dev: pointer to the pci_dev data structure of MSI device function

   * @nvec: how many MSIs have been requested ?

   * @type: are we checking for MSI or MSI-X ?

   *

   * Look at global flags, the device itself, and its parent busses

   * to determine if MSI/-X are supported for the device. If MSI/-X is
   * supported return 0, else return an error code.

   **/

  static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type)

  {
  	struct pci_bus *bus;

  	int ret;

  	/* MSI must be globally enabled and supported by the device */

  	if (!pci_msi_enable || !dev || dev->no_msi)
  		return -EINVAL;

  	/*
  	 * You can't ask to have 0 or less MSIs configured.
  	 *  a) it's stupid ..
  	 *  b) the list manipulation code assumes nvec >= 1.
  	 */
  	if (nvec < 1)
  		return -ERANGE;

  	/*
  	 * Any bridge which does NOT route MSI transactions from its
  	 * secondary bus to its primary bus must set NO_MSI flag on

  	 * the secondary pci_bus.
  	 * We expect only arch-specific PCI host bus controller driver
  	 * or quirks for specific PCI bridges to be setting NO_MSI.
  	 */

  	for (bus = dev->bus; bus; bus = bus->parent)
  		if (bus->bus_flags & PCI_BUS_FLAGS_NO_MSI)
  			return -EINVAL;

  	ret = arch_msi_check_device(dev, nvec, type);
  	if (ret)
  		return ret;

  	if (!pci_find_capability(dev, type))
  		return -EINVAL;

  	return 0;
  }
  
  /**

   * pci_enable_msi_block - configure device's MSI capability structure
   * @dev: device to configure
   * @nvec: number of interrupts to configure

   *

   * Allocate IRQs for a device with the MSI capability.
   * This function returns a negative errno if an error occurs.  If it
   * is unable to allocate the number of interrupts requested, it returns
   * the number of interrupts it might be able to allocate.  If it successfully
   * allocates at least the number of interrupts requested, it returns 0 and
   * updates the @dev's irq member to the lowest new interrupt number; the
   * other interrupt numbers allocated to this device are consecutive.
   */
  int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec)

  {

  	int status, pos, maxvec;
  	u16 msgctl;
  
  	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
  	if (!pos)
  		return -EINVAL;
  	pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl);
  	maxvec = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1);
  	if (nvec > maxvec)
  		return maxvec;

  	status = pci_msi_check_device(dev, nvec, PCI_CAP_ID_MSI);

  	if (status)
  		return status;

  	WARN_ON(!!dev->msi_enabled);

  	/* Check whether driver already requested MSI-X irqs */

  	if (dev->msix_enabled) {

  		dev_info(&dev->dev, "can't enable MSI "
  			 "(MSI-X already enabled)
  ");

  		return -EINVAL;

  	}

  
  	status = msi_capability_init(dev, nvec);

  	return status;
  }

  EXPORT_SYMBOL(pci_enable_msi_block);

  void pci_msi_shutdown(struct pci_dev *dev)

  {

  	struct msi_desc *desc;
  	u32 mask;
  	u16 ctrl;

  	unsigned pos;

  	if (!pci_msi_enable || !dev || !dev->msi_enabled)

  		return;

  	BUG_ON(list_empty(&dev->msi_list));
  	desc = list_first_entry(&dev->msi_list, struct msi_desc, list);
  	pos = desc->msi_attrib.pos;
  
  	msi_set_enable(dev, pos, 0);

  	pci_intx_for_msi(dev, 1);

  	dev->msi_enabled = 0;

  	/* Return the device with MSI unmasked as initial states */

  	pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &ctrl);

  	mask = msi_capable_mask(ctrl);

  	/* Keep cached state to be restored */
  	__msi_mask_irq(desc, mask, ~mask);

  
  	/* Restore dev->irq to its default pin-assertion irq */

  	dev->irq = desc->msi_attrib.default_irq;

  }

  void pci_disable_msi(struct pci_dev *dev)

  {

  	if (!pci_msi_enable || !dev || !dev->msi_enabled)
  		return;
  
  	pci_msi_shutdown(dev);

  	free_msi_irqs(dev);

  	kset_unregister(dev->msi_kset);
  	dev->msi_kset = NULL;

  }

  EXPORT_SYMBOL(pci_disable_msi);

  /**

   * pci_msix_table_size - return the number of device's MSI-X table entries
   * @dev: pointer to the pci_dev data structure of MSI-X device function
   */
  int pci_msix_table_size(struct pci_dev *dev)
  {
  	int pos;
  	u16 control;
  
  	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
  	if (!pos)
  		return 0;
  
  	pci_read_config_word(dev, msi_control_reg(pos), &control);
  	return multi_msix_capable(control);
  }
  
  /**

   * pci_enable_msix - configure device's MSI-X capability structure
   * @dev: pointer to the pci_dev data structure of MSI-X device function

   * @entries: pointer to an array of MSI-X entries

   * @nvec: number of MSI-X irqs requested for allocation by device driver

   *
   * Setup the MSI-X capability structure of device function with the number

   * of requested irqs upon its software driver call to request for

   * MSI-X mode enabled on its hardware device function. A return of zero
   * indicates the successful configuration of MSI-X capability structure

   * with new allocated MSI-X irqs. A return of < 0 indicates a failure.

   * Or a return of > 0 indicates that driver request is exceeding the number

   * of irqs or MSI-X vectors available. Driver should use the returned value to
   * re-send its request.

   **/

  int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)

  {

  	int status, nr_entries;

  	int i, j;

  	if (!entries)

  		return -EINVAL;

  	status = pci_msi_check_device(dev, nvec, PCI_CAP_ID_MSIX);
  	if (status)
  		return status;

  	nr_entries = pci_msix_table_size(dev);

  	if (nvec > nr_entries)

  		return nr_entries;

  
  	/* Check for any invalid entries */
  	for (i = 0; i < nvec; i++) {
  		if (entries[i].entry >= nr_entries)
  			return -EINVAL;		/* invalid entry */
  		for (j = i + 1; j < nvec; j++) {
  			if (entries[i].entry == entries[j].entry)
  				return -EINVAL;	/* duplicate entry */
  		}
  	}

  	WARN_ON(!!dev->msix_enabled);

  	/* Check whether driver already requested for MSI irq */

  	if (dev->msi_enabled) {

  		dev_info(&dev->dev, "can't enable MSI-X "
  		       "(MSI IRQ already assigned)
  ");

  		return -EINVAL;
  	}

  	status = msix_capability_init(dev, entries, nvec);

  	return status;
  }

  EXPORT_SYMBOL(pci_enable_msix);

  void pci_msix_shutdown(struct pci_dev *dev)

  {

  	struct msi_desc *entry;

  	if (!pci_msi_enable || !dev || !dev->msix_enabled)

  		return;

  	/* Return the device with MSI-X masked as initial states */
  	list_for_each_entry(entry, &dev->msi_list, list) {
  		/* Keep cached states to be restored */
  		__msix_mask_irq(entry, 1);
  	}

  	msix_set_enable(dev, 0);

  	pci_intx_for_msi(dev, 1);

  	dev->msix_enabled = 0;

  }

  void pci_disable_msix(struct pci_dev *dev)

  {
  	if (!pci_msi_enable || !dev || !dev->msix_enabled)
  		return;
  
  	pci_msix_shutdown(dev);

  	free_msi_irqs(dev);

  	kset_unregister(dev->msi_kset);
  	dev->msi_kset = NULL;

  }

  EXPORT_SYMBOL(pci_disable_msix);

  
  /**

   * msi_remove_pci_irq_vectors - reclaim MSI(X) irqs to unused state

   * @dev: pointer to the pci_dev data structure of MSI(X) device function
   *

   * Being called during hotplug remove, from which the device function

   * is hot-removed. All previous assigned MSI/MSI-X irqs, if

   * allocated for this device function, are reclaimed to unused state,
   * which may be used later on.
   **/

  void msi_remove_pci_irq_vectors(struct pci_dev *dev)

  {

  	if (!pci_msi_enable || !dev)

  		return;

  	if (dev->msi_enabled || dev->msix_enabled)
  		free_msi_irqs(dev);

  }

  void pci_no_msi(void)
  {
  	pci_msi_enable = 0;
  }

  /**
   * pci_msi_enabled - is MSI enabled?
   *
   * Returns true if MSI has not been disabled by the command-line option
   * pci=nomsi.
   **/
  int pci_msi_enabled(void)

  {

  	return pci_msi_enable;

  }

  EXPORT_SYMBOL(pci_msi_enabled);

  void pci_msi_init_pci_dev(struct pci_dev *dev)

  {

  	int pos;

  	INIT_LIST_HEAD(&dev->msi_list);

  
  	/* Disable the msi hardware to avoid screaming interrupts
  	 * during boot.  This is the power on reset default so
  	 * usually this should be a noop.
  	 */
  	pos = pci_find_capability(dev, PCI_CAP_ID_MSI);
  	if (pos)
  		msi_set_enable(dev, pos, 0);
  	msix_set_enable(dev, 0);

  }