libnvdimm, nfit, nd_blk: driver for BLK-mode access persistent memory
The libnvdimm implementation handles allocating dimm address space (DPA)
between PMEM and BLK mode interfaces. After DPA has been allocated from
a BLK-region to a BLK-namespace the nd_blk driver attaches to handle I/O
as a struct bio based block device. Unlike PMEM, BLK is required to
handle platform specific details like mmio register formats and memory
controller interleave. For this reason the libnvdimm generic nd_blk
driver calls back into the bus provider to carry out the I/O.
This initial implementation handles the BLK interface defined by the
ACPI 6 NFIT [1] and the NVDIMM DSM Interface Example [2] composed from
DCR (dimm control region), BDW (block data window), IDT (interleave
descriptor) NFIT structures and the hardware register format.
[1]: http://www.uefi.org/sites/default/files/resources/ACPI_6.0.pdf
[2]: http://pmem.io/documents/NVDIMM_DSM_Interface_Example.pdf
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Boaz Harrosh <boaz@plexistor.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/nvdimm/blk.c b/drivers/nvdimm/blk.c
new file mode 100644
index 0000000..9ac0c26
--- /dev/null
+++ b/drivers/nvdimm/blk.c
@@ -0,0 +1,245 @@
+/*
+ * NVDIMM Block Window Driver
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/blkdev.h>
+#include <linux/fs.h>
+#include <linux/genhd.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/nd.h>
+#include <linux/sizes.h>
+#include "nd.h"
+
+struct nd_blk_device {
+ struct request_queue *queue;
+ struct gendisk *disk;
+ struct nd_namespace_blk *nsblk;
+ struct nd_blk_region *ndbr;
+ size_t disk_size;
+};
+
+static int nd_blk_major;
+
+static resource_size_t to_dev_offset(struct nd_namespace_blk *nsblk,
+ resource_size_t ns_offset, unsigned int len)
+{
+ int i;
+
+ for (i = 0; i < nsblk->num_resources; i++) {
+ if (ns_offset < resource_size(nsblk->res[i])) {
+ if (ns_offset + len > resource_size(nsblk->res[i])) {
+ dev_WARN_ONCE(&nsblk->common.dev, 1,
+ "illegal request\n");
+ return SIZE_MAX;
+ }
+ return nsblk->res[i]->start + ns_offset;
+ }
+ ns_offset -= resource_size(nsblk->res[i]);
+ }
+
+ dev_WARN_ONCE(&nsblk->common.dev, 1, "request out of range\n");
+ return SIZE_MAX;
+}
+
+static void nd_blk_make_request(struct request_queue *q, struct bio *bio)
+{
+ struct block_device *bdev = bio->bi_bdev;
+ struct gendisk *disk = bdev->bd_disk;
+ struct nd_namespace_blk *nsblk;
+ struct nd_blk_device *blk_dev;
+ struct nd_blk_region *ndbr;
+ struct bvec_iter iter;
+ struct bio_vec bvec;
+ int err = 0, rw;
+
+ blk_dev = disk->private_data;
+ nsblk = blk_dev->nsblk;
+ ndbr = blk_dev->ndbr;
+ rw = bio_data_dir(bio);
+ bio_for_each_segment(bvec, bio, iter) {
+ unsigned int len = bvec.bv_len;
+ resource_size_t dev_offset;
+ void *iobuf;
+
+ BUG_ON(len > PAGE_SIZE);
+
+ dev_offset = to_dev_offset(nsblk,
+ iter.bi_sector << SECTOR_SHIFT, len);
+ if (dev_offset == SIZE_MAX) {
+ err = -EIO;
+ goto out;
+ }
+
+ iobuf = kmap_atomic(bvec.bv_page);
+ err = ndbr->do_io(ndbr, dev_offset, iobuf + bvec.bv_offset,
+ len, rw);
+ kunmap_atomic(iobuf);
+ if (err)
+ goto out;
+ }
+
+ out:
+ bio_endio(bio, err);
+}
+
+static int nd_blk_rw_bytes(struct nd_namespace_common *ndns,
+ resource_size_t offset, void *iobuf, size_t n, int rw)
+{
+ struct nd_blk_device *blk_dev = dev_get_drvdata(ndns->claim);
+ struct nd_namespace_blk *nsblk = blk_dev->nsblk;
+ struct nd_blk_region *ndbr = blk_dev->ndbr;
+ resource_size_t dev_offset;
+
+ dev_offset = to_dev_offset(nsblk, offset, n);
+
+ if (unlikely(offset + n > blk_dev->disk_size)) {
+ dev_WARN_ONCE(&ndns->dev, 1, "request out of range\n");
+ return -EFAULT;
+ }
+
+ if (dev_offset == SIZE_MAX)
+ return -EIO;
+
+ return ndbr->do_io(ndbr, dev_offset, iobuf, n, rw);
+}
+
+static const struct block_device_operations nd_blk_fops = {
+ .owner = THIS_MODULE,
+};
+
+static int nd_blk_attach_disk(struct nd_namespace_common *ndns,
+ struct nd_blk_device *blk_dev)
+{
+ struct nd_namespace_blk *nsblk = to_nd_namespace_blk(&ndns->dev);
+ struct gendisk *disk;
+
+ blk_dev->queue = blk_alloc_queue(GFP_KERNEL);
+ if (!blk_dev->queue)
+ return -ENOMEM;
+
+ blk_queue_make_request(blk_dev->queue, nd_blk_make_request);
+ blk_queue_max_hw_sectors(blk_dev->queue, UINT_MAX);
+ blk_queue_bounce_limit(blk_dev->queue, BLK_BOUNCE_ANY);
+ blk_queue_logical_block_size(blk_dev->queue, nsblk->lbasize);
+ queue_flag_set_unlocked(QUEUE_FLAG_NONROT, blk_dev->queue);
+
+ disk = blk_dev->disk = alloc_disk(0);
+ if (!disk) {
+ blk_cleanup_queue(blk_dev->queue);
+ return -ENOMEM;
+ }
+
+ disk->driverfs_dev = &ndns->dev;
+ disk->major = nd_blk_major;
+ disk->first_minor = 0;
+ disk->fops = &nd_blk_fops;
+ disk->private_data = blk_dev;
+ disk->queue = blk_dev->queue;
+ disk->flags = GENHD_FL_EXT_DEVT;
+ nvdimm_namespace_disk_name(ndns, disk->disk_name);
+ set_capacity(disk, blk_dev->disk_size >> SECTOR_SHIFT);
+ add_disk(disk);
+
+ return 0;
+}
+
+static int nd_blk_probe(struct device *dev)
+{
+ struct nd_namespace_common *ndns;
+ struct nd_blk_device *blk_dev;
+ int rc;
+
+ ndns = nvdimm_namespace_common_probe(dev);
+ if (IS_ERR(ndns))
+ return PTR_ERR(ndns);
+
+ blk_dev = kzalloc(sizeof(*blk_dev), GFP_KERNEL);
+ if (!blk_dev)
+ return -ENOMEM;
+
+ blk_dev->disk_size = nvdimm_namespace_capacity(ndns);
+ blk_dev->ndbr = to_nd_blk_region(dev->parent);
+ blk_dev->nsblk = to_nd_namespace_blk(&ndns->dev);
+ dev_set_drvdata(dev, blk_dev);
+
+ ndns->rw_bytes = nd_blk_rw_bytes;
+ if (is_nd_btt(dev))
+ rc = nvdimm_namespace_attach_btt(ndns);
+ else if (nd_btt_probe(ndns, blk_dev) == 0) {
+ /* we'll come back as btt-blk */
+ rc = -ENXIO;
+ } else
+ rc = nd_blk_attach_disk(ndns, blk_dev);
+ if (rc)
+ kfree(blk_dev);
+ return rc;
+}
+
+static void nd_blk_detach_disk(struct nd_blk_device *blk_dev)
+{
+ del_gendisk(blk_dev->disk);
+ put_disk(blk_dev->disk);
+ blk_cleanup_queue(blk_dev->queue);
+}
+
+static int nd_blk_remove(struct device *dev)
+{
+ struct nd_blk_device *blk_dev = dev_get_drvdata(dev);
+
+ if (is_nd_btt(dev))
+ nvdimm_namespace_detach_btt(to_nd_btt(dev)->ndns);
+ else
+ nd_blk_detach_disk(blk_dev);
+ kfree(blk_dev);
+
+ return 0;
+}
+
+static struct nd_device_driver nd_blk_driver = {
+ .probe = nd_blk_probe,
+ .remove = nd_blk_remove,
+ .drv = {
+ .name = "nd_blk",
+ },
+ .type = ND_DRIVER_NAMESPACE_BLK,
+};
+
+static int __init nd_blk_init(void)
+{
+ int rc;
+
+ rc = register_blkdev(0, "nd_blk");
+ if (rc < 0)
+ return rc;
+
+ nd_blk_major = rc;
+ rc = nd_driver_register(&nd_blk_driver);
+
+ if (rc < 0)
+ unregister_blkdev(nd_blk_major, "nd_blk");
+
+ return rc;
+}
+
+static void __exit nd_blk_exit(void)
+{
+ driver_unregister(&nd_blk_driver.drv);
+ unregister_blkdev(nd_blk_major, "nd_blk");
+}
+
+MODULE_AUTHOR("Ross Zwisler <ross.zwisler@linux.intel.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_BLK);
+module_init(nd_blk_init);
+module_exit(nd_blk_exit);