1/*
2 * Copyright (c) 2016 Christoph Hellwig.
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms and conditions of the GNU General Public License,
6 * version 2, as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
12 */
13#include <linux/kobject.h>
14#include <linux/blkdev.h>
15#include <linux/blk-mq.h>
16#include <linux/blk-mq-pci.h>
17#include <linux/pci.h>
18#include <linux/module.h>
19
20#include "blk-mq.h"
21
22/**
23 * blk_mq_pci_map_queues - provide a default queue mapping for PCI device
24 * @set: tagset to provide the mapping for
25 * @pdev: PCI device associated with @set.
26 * @offset: Offset to use for the pci irq vector
27 *
28 * This function assumes the PCI device @pdev has at least as many available
29 * interrupt vectors as @set has queues. It will then query the vector
30 * corresponding to each queue for it's affinity mask and built queue mapping
31 * that maps a queue to the CPUs that have irq affinity for the corresponding
32 * vector.
33 */
34int blk_mq_pci_map_queues(struct blk_mq_queue_map *qmap, struct pci_dev *pdev,
35 int offset)
36{
37 const struct cpumask *mask;
38 unsigned int queue, cpu;
39
40 for (queue = 0; queue < qmap->nr_queues; queue++) {
41 mask = pci_irq_get_affinity(pdev, queue + offset);
42 if (!mask)
43 goto fallback;
44
45 for_each_cpu(cpu, mask)
46 qmap->mq_map[cpu] = qmap->queue_offset + queue;
47 }
48
49 return 0;
50
51fallback:
52 WARN_ON_ONCE(qmap->nr_queues > 1);
53 blk_mq_clear_mq_map(qmap);
54 return 0;
55}
56EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);
57