// SPDX-License-Identifier: GPL-2.0

  /*
   * Copyright (c) 2016 Christoph Hellwig.

   */

  #include <linux/kobject.h>
  #include <linux/blkdev.h>

  #include <linux/blk-mq.h>
  #include <linux/blk-mq-pci.h>
  #include <linux/pci.h>
  #include <linux/module.h>

  #include "blk-mq.h"

  /**
   * blk_mq_pci_map_queues - provide a default queue mapping for PCI device

   * @qmap:	CPU to hardware queue map.

   * @pdev:	PCI device associated with @set.

   * @offset:	Offset to use for the pci irq vector

   *
   * This function assumes the PCI device @pdev has at least as many available

   * interrupt vectors as @set has queues.  It will then query the vector

   * corresponding to each queue for it's affinity mask and built queue mapping
   * that maps a queue to the CPUs that have irq affinity for the corresponding
   * vector.
   */

  int blk_mq_pci_map_queues(struct blk_mq_queue_map *qmap, struct pci_dev *pdev,

  			    int offset)

  {
  	const struct cpumask *mask;
  	unsigned int queue, cpu;

  	for (queue = 0; queue < qmap->nr_queues; queue++) {

  		mask = pci_irq_get_affinity(pdev, queue + offset);

  		if (!mask)

  			goto fallback;

  
  		for_each_cpu(cpu, mask)

  			qmap->mq_map[cpu] = qmap->queue_offset + queue;

  	}
  
  	return 0;

  
  fallback:

  	WARN_ON_ONCE(qmap->nr_queues > 1);
  	blk_mq_clear_mq_map(qmap);

  	return 0;

  }
  EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);