1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * Copyright (c) 2016 Christoph Hellwig.
 4 */
 5#include <linux/kobject.h>
 6#include <linux/blkdev.h>
 7#include <linux/blk-mq.h>
 8#include <linux/blk-mq-pci.h>
 9#include <linux/pci.h>
10#include <linux/module.h>
11
12#include "blk-mq.h"
13
14/**
15 * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
16 * @qmap:	CPU to hardware queue map.
17 * @pdev:	PCI device associated with @set.
18 * @offset:	Offset to use for the pci irq vector
19 *
20 * This function assumes the PCI device @pdev has at least as many available
21 * interrupt vectors as @set has queues.  It will then query the vector
22 * corresponding to each queue for it's affinity mask and built queue mapping
23 * that maps a queue to the CPUs that have irq affinity for the corresponding
24 * vector.
25 */
26void blk_mq_pci_map_queues(struct blk_mq_queue_map *qmap, struct pci_dev *pdev,
27			   int offset)
28{
29	const struct cpumask *mask;
30	unsigned int queue, cpu;
31
32	for (queue = 0; queue < qmap->nr_queues; queue++) {
33		mask = pci_irq_get_affinity(pdev, queue + offset);
34		if (!mask)
35			goto fallback;
36
37		for_each_cpu(cpu, mask)
38			qmap->mq_map[cpu] = qmap->queue_offset + queue;
39	}
40
41	return;
42
43fallback:
44	WARN_ON_ONCE(qmap->nr_queues > 1);
45	blk_mq_clear_mq_map(qmap);
46}
47EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);