linux/drivers/block/pmem.c

263 lines
6.0 KiB
C

/*
* Persistent Memory Driver
*
* Copyright (c) 2014, Intel Corporation.
* Copyright (c) 2015, Christoph Hellwig <hch@lst.de>.
* Copyright (c) 2015, Boaz Harrosh <boaz@plexistor.com>.
*
* 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 <asm/cacheflush.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#define PMEM_MINORS 16
struct pmem_device {
struct request_queue *pmem_queue;
struct gendisk *pmem_disk;
/* One contiguous memory region per device */
phys_addr_t phys_addr;
void *virt_addr;
size_t size;
};
static int pmem_major;
static atomic_t pmem_index;
static void pmem_do_bvec(struct pmem_device *pmem, struct page *page,
unsigned int len, unsigned int off, int rw,
sector_t sector)
{
void *mem = kmap_atomic(page);
size_t pmem_off = sector << 9;
if (rw == READ) {
memcpy(mem + off, pmem->virt_addr + pmem_off, len);
flush_dcache_page(page);
} else {
flush_dcache_page(page);
memcpy(pmem->virt_addr + pmem_off, mem + off, len);
}
kunmap_atomic(mem);
}
static void pmem_make_request(struct request_queue *q, struct bio *bio)
{
struct block_device *bdev = bio->bi_bdev;
struct pmem_device *pmem = bdev->bd_disk->private_data;
int rw;
struct bio_vec bvec;
sector_t sector;
struct bvec_iter iter;
int err = 0;
if (bio_end_sector(bio) > get_capacity(bdev->bd_disk)) {
err = -EIO;
goto out;
}
BUG_ON(bio->bi_rw & REQ_DISCARD);
rw = bio_data_dir(bio);
sector = bio->bi_iter.bi_sector;
bio_for_each_segment(bvec, bio, iter) {
pmem_do_bvec(pmem, bvec.bv_page, bvec.bv_len, bvec.bv_offset,
rw, sector);
sector += bvec.bv_len >> 9;
}
out:
bio_endio(bio, err);
}
static int pmem_rw_page(struct block_device *bdev, sector_t sector,
struct page *page, int rw)
{
struct pmem_device *pmem = bdev->bd_disk->private_data;
pmem_do_bvec(pmem, page, PAGE_CACHE_SIZE, 0, rw, sector);
page_endio(page, rw & WRITE, 0);
return 0;
}
static long pmem_direct_access(struct block_device *bdev, sector_t sector,
void **kaddr, unsigned long *pfn, long size)
{
struct pmem_device *pmem = bdev->bd_disk->private_data;
size_t offset = sector << 9;
if (!pmem)
return -ENODEV;
*kaddr = pmem->virt_addr + offset;
*pfn = (pmem->phys_addr + offset) >> PAGE_SHIFT;
return pmem->size - offset;
}
static const struct block_device_operations pmem_fops = {
.owner = THIS_MODULE,
.rw_page = pmem_rw_page,
.direct_access = pmem_direct_access,
};
static struct pmem_device *pmem_alloc(struct device *dev, struct resource *res)
{
struct pmem_device *pmem;
struct gendisk *disk;
int idx, err;
err = -ENOMEM;
pmem = kzalloc(sizeof(*pmem), GFP_KERNEL);
if (!pmem)
goto out;
pmem->phys_addr = res->start;
pmem->size = resource_size(res);
err = -EINVAL;
if (!request_mem_region(pmem->phys_addr, pmem->size, "pmem")) {
dev_warn(dev, "could not reserve region [0x%pa:0x%zx]\n", &pmem->phys_addr, pmem->size);
goto out_free_dev;
}
/*
* Map the memory as non-cachable, as we can't write back the contents
* of the CPU caches in case of a crash.
*/
err = -ENOMEM;
pmem->virt_addr = ioremap_nocache(pmem->phys_addr, pmem->size);
if (!pmem->virt_addr)
goto out_release_region;
pmem->pmem_queue = blk_alloc_queue(GFP_KERNEL);
if (!pmem->pmem_queue)
goto out_unmap;
blk_queue_make_request(pmem->pmem_queue, pmem_make_request);
blk_queue_max_hw_sectors(pmem->pmem_queue, 1024);
blk_queue_bounce_limit(pmem->pmem_queue, BLK_BOUNCE_ANY);
disk = alloc_disk(PMEM_MINORS);
if (!disk)
goto out_free_queue;
idx = atomic_inc_return(&pmem_index) - 1;
disk->major = pmem_major;
disk->first_minor = PMEM_MINORS * idx;
disk->fops = &pmem_fops;
disk->private_data = pmem;
disk->queue = pmem->pmem_queue;
disk->flags = GENHD_FL_EXT_DEVT;
sprintf(disk->disk_name, "pmem%d", idx);
disk->driverfs_dev = dev;
set_capacity(disk, pmem->size >> 9);
pmem->pmem_disk = disk;
add_disk(disk);
return pmem;
out_free_queue:
blk_cleanup_queue(pmem->pmem_queue);
out_unmap:
iounmap(pmem->virt_addr);
out_release_region:
release_mem_region(pmem->phys_addr, pmem->size);
out_free_dev:
kfree(pmem);
out:
return ERR_PTR(err);
}
static void pmem_free(struct pmem_device *pmem)
{
del_gendisk(pmem->pmem_disk);
put_disk(pmem->pmem_disk);
blk_cleanup_queue(pmem->pmem_queue);
iounmap(pmem->virt_addr);
release_mem_region(pmem->phys_addr, pmem->size);
kfree(pmem);
}
static int pmem_probe(struct platform_device *pdev)
{
struct pmem_device *pmem;
struct resource *res;
if (WARN_ON(pdev->num_resources > 1))
return -ENXIO;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENXIO;
pmem = pmem_alloc(&pdev->dev, res);
if (IS_ERR(pmem))
return PTR_ERR(pmem);
platform_set_drvdata(pdev, pmem);
return 0;
}
static int pmem_remove(struct platform_device *pdev)
{
struct pmem_device *pmem = platform_get_drvdata(pdev);
pmem_free(pmem);
return 0;
}
static struct platform_driver pmem_driver = {
.probe = pmem_probe,
.remove = pmem_remove,
.driver = {
.owner = THIS_MODULE,
.name = "pmem",
},
};
static int __init pmem_init(void)
{
int error;
pmem_major = register_blkdev(0, "pmem");
if (pmem_major < 0)
return pmem_major;
error = platform_driver_register(&pmem_driver);
if (error)
unregister_blkdev(pmem_major, "pmem");
return error;
}
module_init(pmem_init);
static void pmem_exit(void)
{
platform_driver_unregister(&pmem_driver);
unregister_blkdev(pmem_major, "pmem");
}
module_exit(pmem_exit);
MODULE_AUTHOR("Ross Zwisler <ross.zwisler@linux.intel.com>");
MODULE_LICENSE("GPL v2");