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 */ 34 int 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 51 fallback: 52 WARN_ON_ONCE(qmap->nr_queues > 1); 53 blk_mq_clear_mq_map(qmap); 54 return 0; 55 } 56 EXPORT_SYMBOL_GPL(blk_mq_pci_map_queues); 57