// SPDX-License-Identifier: GPL-2.0
  /*
   * PCI IRQ handling code
   *
   * Copyright (c) 2008 James Bottomley <James.Bottomley@HansenPartnership.com>
   * Copyright (C) 2017 Christoph Hellwig.
   */
  
  #include <linux/acpi.h>
  #include <linux/device.h>
  #include <linux/kernel.h>
  #include <linux/export.h>
  #include <linux/pci.h>
  
  static void pci_note_irq_problem(struct pci_dev *pdev, const char *reason)
  {
  	struct pci_dev *parent = to_pci_dev(pdev->dev.parent);
  
  	dev_err(&pdev->dev,
  		"Potentially misrouted IRQ (Bridge %s %04x:%04x)
  ",
  		dev_name(&parent->dev), parent->vendor, parent->device);
  	dev_err(&pdev->dev, "%s
  ", reason);
  	dev_err(&pdev->dev, "Please report to linux-kernel@vger.kernel.org
  ");
  	WARN_ON(1);
  }
  
  /**
   * pci_lost_interrupt - reports a lost PCI interrupt
   * @pdev:	device whose interrupt is lost
   *
   * The primary function of this routine is to report a lost interrupt
   * in a standard way which users can recognise (instead of blaming the
   * driver).
   *
   * Returns:
   * a suggestion for fixing it (although the driver is not required to
   * act on this).
   */
  enum pci_lost_interrupt_reason pci_lost_interrupt(struct pci_dev *pdev)
  {
  	if (pdev->msi_enabled || pdev->msix_enabled) {
  		enum pci_lost_interrupt_reason ret;
  
  		if (pdev->msix_enabled) {
  			pci_note_irq_problem(pdev, "MSIX routing failure");
  			ret = PCI_LOST_IRQ_DISABLE_MSIX;
  		} else {
  			pci_note_irq_problem(pdev, "MSI routing failure");
  			ret = PCI_LOST_IRQ_DISABLE_MSI;
  		}
  		return ret;
  	}
  #ifdef CONFIG_ACPI
  	if (!(acpi_disabled || acpi_noirq)) {
  		pci_note_irq_problem(pdev, "Potential ACPI misrouting please reboot with acpi=noirq");
  		/* currently no way to fix acpi on the fly */
  		return PCI_LOST_IRQ_DISABLE_ACPI;
  	}
  #endif
  	pci_note_irq_problem(pdev, "unknown cause (not MSI or ACPI)");
  	return PCI_LOST_IRQ_NO_INFORMATION;
  }
  EXPORT_SYMBOL(pci_lost_interrupt);
  
  /**
   * pci_request_irq - allocate an interrupt line for a PCI device
   * @dev:	PCI device to operate on
   * @nr:		device-relative interrupt vector index (0-based).
   * @handler:	Function to be called when the IRQ occurs.
   *		Primary handler for threaded interrupts.
   *		If NULL and thread_fn != NULL the default primary handler is
   *		installed.
   * @thread_fn:	Function called from the IRQ handler thread
   *		If NULL, no IRQ thread is created
   * @dev_id:	Cookie passed back to the handler function
   * @fmt:	Printf-like format string naming the handler
   *
   * This call allocates interrupt resources and enables the interrupt line and
   * IRQ handling. From the point this call is made @handler and @thread_fn may
   * be invoked.  All interrupts requested using this function might be shared.
   *
   * @dev_id must not be NULL and must be globally unique.
   */
  int pci_request_irq(struct pci_dev *dev, unsigned int nr, irq_handler_t handler,
  		irq_handler_t thread_fn, void *dev_id, const char *fmt, ...)
  {
  	va_list ap;
  	int ret;
  	char *devname;
  
  	va_start(ap, fmt);
  	devname = kvasprintf(GFP_KERNEL, fmt, ap);
  	va_end(ap);
  
  	ret = request_threaded_irq(pci_irq_vector(dev, nr), handler, thread_fn,
  			IRQF_SHARED, devname, dev_id);
  	if (ret)
  		kfree(devname);
  	return ret;
  }
  EXPORT_SYMBOL(pci_request_irq);
  
  /**
   * pci_free_irq - free an interrupt allocated with pci_request_irq
   * @dev:	PCI device to operate on
   * @nr:		device-relative interrupt vector index (0-based).
   * @dev_id:	Device identity to free
   *
   * Remove an interrupt handler. The handler is removed and if the interrupt
   * line is no longer in use by any driver it is disabled.  The caller must
   * ensure the interrupt is disabled on the device before calling this function.
   * The function does not return until any executing interrupts for this IRQ
   * have completed.
   *
   * This function must not be called from interrupt context.
   */
  void pci_free_irq(struct pci_dev *dev, unsigned int nr, void *dev_id)
  {
  	kfree(free_irq(pci_irq_vector(dev, nr), dev_id));
  }
  EXPORT_SYMBOL(pci_free_irq);