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  */
blk_mq_pci_map_queues(struct blk_mq_queue_map * qmap,struct pci_dev * pdev,int offset)26 void 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 
43 fallback:
44 	WARN_ON_ONCE(qmap->nr_queues > 1);
45 	blk_mq_clear_mq_map(qmap);
46 }
47 EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues);
48