/*
 * Persistent Memory Driver
 *
 * Copyright (c) 2014-2015, 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/set_memory.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/badblocks.h>
#include <linux/memremap.h>
#include <linux/vmalloc.h>
#include <linux/blk-mq.h>
#include <linux/pfn_t.h>
#include <linux/slab.h>
#include <linux/uio.h>
#include <linux/dax.h>
#include <linux/nd.h>
#include <linux/backing-dev.h>
#include "pmem.h"
#include "pfn.h"
#include "nd.h"
#include "nd-core.h"

static struct device *to_dev(struct pmem_device *pmem)
{
        /*
         * nvdimm bus services need a 'dev' parameter, and we record the device
         * at init in bb.dev.
         */
        return pmem->bb.dev;
}

static struct nd_region *to_region(struct pmem_device *pmem)
{
        return to_nd_region(to_dev(pmem)->parent);
}

static void hwpoison_clear(struct pmem_device *pmem,
                phys_addr_t phys, unsigned int len)
{
        unsigned long pfn_start, pfn_end, pfn;

        /* only pmem in the linear map supports HWPoison */
        if (is_vmalloc_addr(pmem->virt_addr))
                return;

        pfn_start = PHYS_PFN(phys);
        pfn_end = pfn_start + PHYS_PFN(len);
        for (pfn = pfn_start; pfn < pfn_end; pfn++) {
                struct page *page = pfn_to_page(pfn);

                /*
                 * Note, no need to hold a get_dev_pagemap() reference
                 * here since we're in the driver I/O path and
                 * outstanding I/O requests pin the dev_pagemap.
                 */
                if (test_and_clear_pmem_poison(page))
                        clear_mce_nospec(pfn);
        }
}

static blk_status_t pmem_clear_poison(struct pmem_device *pmem,
                phys_addr_t offset, unsigned int len)
{
        struct device *dev = to_dev(pmem);
        sector_t sector;
        long cleared;
        blk_status_t rc = BLK_STS_OK;

        sector = (offset - pmem->data_offset) / 512;

        cleared = nvdimm_clear_poison(dev, pmem->phys_addr + offset, len);
        if (cleared < len)
                rc = BLK_STS_IOERR;
        if (cleared > 0 && cleared / 512) {
                hwpoison_clear(pmem, pmem->phys_addr + offset, cleared);
                cleared /= 512;
                dev_dbg(dev, "%#llx clear %ld sector%s\n",
                                (unsigned long long) sector, cleared,
                                cleared > 1 ? "s" : "");
                badblocks_clear(&pmem->bb, sector, cleared);
                if (pmem->bb_state)
                        sysfs_notify_dirent(pmem->bb_state);
        }

        arch_invalidate_pmem(pmem->virt_addr + offset, len);

        return rc;
}

static void write_pmem(void *pmem_addr, struct page *page,
                unsigned int off, unsigned int len)
{
        unsigned int chunk;
        void *mem;

        while (len) {
                mem = kmap_atomic(page);
                chunk = min_t(unsigned int, len, PAGE_SIZE);
                memcpy_flushcache(pmem_addr, mem + off, chunk);
                kunmap_atomic(mem);
                len -= chunk;
                off = 0;
                page++;
                pmem_addr += PAGE_SIZE;
        }
}

static blk_status_t read_pmem(struct page *page, unsigned int off,
                void *pmem_addr, unsigned int len)
{
        unsigned int chunk;
        unsigned long rem;
        void *mem;

        while (len) {
                mem = kmap_atomic(page);
                chunk = min_t(unsigned int, len, PAGE_SIZE);
                rem = memcpy_mcsafe(mem + off, pmem_addr, chunk);
                kunmap_atomic(mem);
                if (rem)
                        return BLK_STS_IOERR;
                len -= chunk;
                off = 0;
                page++;
                pmem_addr += PAGE_SIZE;
        }
        return BLK_STS_OK;
}

static blk_status_t pmem_do_bvec(struct pmem_device *pmem, struct page *page,
                        unsigned int len, unsigned int off, unsigned int op,
                        sector_t sector)
{
        blk_status_t rc = BLK_STS_OK;
        bool bad_pmem = false;
        phys_addr_t pmem_off = sector * 512 + pmem->data_offset;
        void *pmem_addr = pmem->virt_addr + pmem_off;

        if (unlikely(is_bad_pmem(&pmem->bb, sector, len)))
                bad_pmem = true;

        if (!op_is_write(op)) {
                if (unlikely(bad_pmem))
                        rc = BLK_STS_IOERR;
                else {
                        rc = read_pmem(page, off, pmem_addr, len);
                        flush_dcache_page(page);
                }
        } else {
                /*
                 * Note that we write the data both before and after
                 * clearing poison.  The write before clear poison
                 * handles situations where the latest written data is
                 * preserved and the clear poison operation simply marks
                 * the address range as valid without changing the data.
                 * In this case application software can assume that an
                 * interrupted write will either return the new good
                 * data or an error.
                 *
                 * However, if pmem_clear_poison() leaves the data in an
                 * indeterminate state we need to perform the write
                 * after clear poison.
                 */
                flush_dcache_page(page);
                write_pmem(pmem_addr, page, off, len);
                if (unlikely(bad_pmem)) {
                        rc = pmem_clear_poison(pmem, pmem_off, len);
                        write_pmem(pmem_addr, page, off, len);
                }
        }

        return rc;
}

static blk_qc_t pmem_make_request(struct request_queue *q, struct bio *bio)
{
        blk_status_t rc = 0;
        bool do_acct;
        unsigned long start;
        struct bio_vec bvec;
        struct bvec_iter iter;
        struct pmem_device *pmem = q->queuedata;
        struct nd_region *nd_region = to_region(pmem);

        if (bio->bi_opf & REQ_PREFLUSH)
                nvdimm_flush(nd_region);

        do_acct = nd_iostat_start(bio, &start);
        bio_for_each_segment(bvec, bio, iter) {
                rc = pmem_do_bvec(pmem, bvec.bv_page, bvec.bv_len,
                                bvec.bv_offset, bio_op(bio), iter.bi_sector);
                if (rc) {
                        bio->bi_status = rc;
                        break;
                }
        }
        if (do_acct)
                nd_iostat_end(bio, start);

        if (bio->bi_opf & REQ_FUA)
                nvdimm_flush(nd_region);

        bio_endio(bio);
        return BLK_QC_T_NONE;
}

static int pmem_rw_page(struct block_device *bdev, sector_t sector,
                       struct page *page, unsigned int op)
{
        struct pmem_device *pmem = bdev->bd_queue->queuedata;
        blk_status_t rc;

        rc = pmem_do_bvec(pmem, page, hpage_nr_pages(page) * PAGE_SIZE,
                          0, op, sector);

        /*
         * The ->rw_page interface is subtle and tricky.  The core
         * retries on any error, so we can only invoke page_endio() in
         * the successful completion case.  Otherwise, we'll see crashes
         * caused by double completion.
         */
        if (rc == 0)
                page_endio(page, op_is_write(op), 0);

        return blk_status_to_errno(rc);
}

/* see "strong" declaration in tools/testing/nvdimm/pmem-dax.c */
__weak long __pmem_direct_access(struct pmem_device *pmem, pgoff_t pgoff,
                long nr_pages, void **kaddr, pfn_t *pfn)
{
        resource_size_t offset = PFN_PHYS(pgoff) + pmem->data_offset;

        if (unlikely(is_bad_pmem(&pmem->bb, PFN_PHYS(pgoff) / 512,
                                        PFN_PHYS(nr_pages))))
                return -EIO;

        if (kaddr)
                *kaddr = pmem->virt_addr + offset;
        if (pfn)
                *pfn = phys_to_pfn_t(pmem->phys_addr + offset, pmem->pfn_flags);

        /*
         * If badblocks are present, limit known good range to the
         * requested range.
         */
        if (unlikely(pmem->bb.count))
                return nr_pages;
        return PHYS_PFN(pmem->size - pmem->pfn_pad - offset);
}

static const struct block_device_operations pmem_fops = {
        .owner =                THIS_MODULE,
        .rw_page =              pmem_rw_page,
        .revalidate_disk =      nvdimm_revalidate_disk,
};

static long pmem_dax_direct_access(struct dax_device *dax_dev,
                pgoff_t pgoff, long nr_pages, void **kaddr, pfn_t *pfn)
{
        struct pmem_device *pmem = dax_get_private(dax_dev);

        return __pmem_direct_access(pmem, pgoff, nr_pages, kaddr, pfn);
}

static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
                void *addr, size_t bytes, struct iov_iter *i)
{
        return copy_from_iter_flushcache(addr, bytes, i);
}

static size_t pmem_copy_to_iter(struct dax_device *dax_dev, pgoff_t pgoff,
                void *addr, size_t bytes, struct iov_iter *i)
{
        return copy_to_iter_mcsafe(addr, bytes, i);
}

static const struct dax_operations pmem_dax_ops = {
        .direct_access = pmem_dax_direct_access,
        .copy_from_iter = pmem_copy_from_iter,
        .copy_to_iter = pmem_copy_to_iter,
};

static const struct attribute_group *pmem_attribute_groups[] = {
        &dax_attribute_group,
        NULL,
};

static void pmem_release_queue(void *q)
{
        blk_cleanup_queue(q);
}

static void pmem_freeze_queue(void *q)
{
        blk_freeze_queue_start(q);
}

static void pmem_release_disk(void *__pmem)
{
        struct pmem_device *pmem = __pmem;

        kill_dax(pmem->dax_dev);
        put_dax(pmem->dax_dev);
        del_gendisk(pmem->disk);
        put_disk(pmem->disk);
}

static void pmem_release_pgmap_ops(void *__pgmap)
{
        dev_pagemap_put_ops();
}

static void fsdax_pagefree(struct page *page, void *data)
{
        wake_up_var(&page->_refcount);
}

static int setup_pagemap_fsdax(struct device *dev, struct dev_pagemap *pgmap)
{
        dev_pagemap_get_ops();
        if (devm_add_action_or_reset(dev, pmem_release_pgmap_ops, pgmap))
                return -ENOMEM;
        pgmap->type = MEMORY_DEVICE_FS_DAX;
        pgmap->page_free = fsdax_pagefree;

        return 0;
}

static int pmem_attach_disk(struct device *dev,
                struct nd_namespace_common *ndns)
{
        struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
        struct nd_region *nd_region = to_nd_region(dev->parent);
        int nid = dev_to_node(dev), fua;
        struct resource *res = &nsio->res;
        struct resource bb_res;
        struct nd_pfn *nd_pfn = NULL;
        struct dax_device *dax_dev;
        struct nd_pfn_sb *pfn_sb;
        struct pmem_device *pmem;
        struct request_queue *q;
        struct device *gendev;
        struct gendisk *disk;
        void *addr;
        int rc;

        pmem = devm_kzalloc(dev, sizeof(*pmem), GFP_KERNEL);
        if (!pmem)
                return -ENOMEM;

        /* while nsio_rw_bytes is active, parse a pfn info block if present */
        if (is_nd_pfn(dev)) {
                nd_pfn = to_nd_pfn(dev);
                rc = nvdimm_setup_pfn(nd_pfn, &pmem->pgmap);
                if (rc)
                        return rc;
        }

        /* we're attaching a block device, disable raw namespace access */
        devm_nsio_disable(dev, nsio);

        dev_set_drvdata(dev, pmem);
        pmem->phys_addr = res->start;
        pmem->size = resource_size(res);
        fua = nvdimm_has_flush(nd_region);
        if (!IS_ENABLED(CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE) || fua < 0) {
                dev_warn(dev, "unable to guarantee persistence of writes\n");
                fua = 0;
        }

        if (!devm_request_mem_region(dev, res->start, resource_size(res),
                                dev_name(&ndns->dev))) {
                dev_warn(dev, "could not reserve region %pR\n", res);
                return -EBUSY;
        }

        q = blk_alloc_queue_node(GFP_KERNEL, dev_to_node(dev), NULL);
        if (!q)
                return -ENOMEM;

        if (devm_add_action_or_reset(dev, pmem_release_queue, q))
                return -ENOMEM;

        pmem->pfn_flags = PFN_DEV;
        pmem->pgmap.ref = &q->q_usage_counter;
        if (is_nd_pfn(dev)) {
                if (setup_pagemap_fsdax(dev, &pmem->pgmap))
                        return -ENOMEM;
                addr = devm_memremap_pages(dev, &pmem->pgmap);
                pfn_sb = nd_pfn->pfn_sb;
                pmem->data_offset = le64_to_cpu(pfn_sb->dataoff);
                pmem->pfn_pad = resource_size(res) -
                        resource_size(&pmem->pgmap.res);
                pmem->pfn_flags |= PFN_MAP;
                memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));
                bb_res.start += pmem->data_offset;
        } else if (pmem_should_map_pages(dev)) {
                memcpy(&pmem->pgmap.res, &nsio->res, sizeof(pmem->pgmap.res));
                pmem->pgmap.altmap_valid = false;
                if (setup_pagemap_fsdax(dev, &pmem->pgmap))
                        return -ENOMEM;
                addr = devm_memremap_pages(dev, &pmem->pgmap);
                pmem->pfn_flags |= PFN_MAP;
                memcpy(&bb_res, &pmem->pgmap.res, sizeof(bb_res));
        } else
                addr = devm_memremap(dev, pmem->phys_addr,
                                pmem->size, ARCH_MEMREMAP_PMEM);

        /*
         * At release time the queue must be frozen before
         * devm_memremap_pages is unwound
         */
        if (devm_add_action_or_reset(dev, pmem_freeze_queue, q))
                return -ENOMEM;

        if (IS_ERR(addr))
                return PTR_ERR(addr);
        pmem->virt_addr = addr;

        blk_queue_write_cache(q, true, fua);
        blk_queue_make_request(q, pmem_make_request);
        blk_queue_physical_block_size(q, PAGE_SIZE);
        blk_queue_logical_block_size(q, pmem_sector_size(ndns));
        blk_queue_max_hw_sectors(q, UINT_MAX);
        blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
        if (pmem->pfn_flags & PFN_MAP)
                blk_queue_flag_set(QUEUE_FLAG_DAX, q);
        q->queuedata = pmem;

        disk = alloc_disk_node(0, nid);
        if (!disk)
                return -ENOMEM;
        pmem->disk = disk;

        disk->fops              = &pmem_fops;
        disk->queue             = q;
        disk->flags             = GENHD_FL_EXT_DEVT;
        disk->queue->backing_dev_info->capabilities |= BDI_CAP_SYNCHRONOUS_IO;
        nvdimm_namespace_disk_name(ndns, disk->disk_name);
        set_capacity(disk, (pmem->size - pmem->pfn_pad - pmem->data_offset)
                        / 512);
        if (devm_init_badblocks(dev, &pmem->bb))
                return -ENOMEM;
        nvdimm_badblocks_populate(nd_region, &pmem->bb, &bb_res);
        disk->bb = &pmem->bb;

        dax_dev = alloc_dax(pmem, disk->disk_name, &pmem_dax_ops);
        if (!dax_dev) {
                put_disk(disk);
                return -ENOMEM;
        }
        dax_write_cache(dax_dev, nvdimm_has_cache(nd_region));
        pmem->dax_dev = dax_dev;

        gendev = disk_to_dev(disk);
        gendev->groups = pmem_attribute_groups;

        device_add_disk(dev, disk);
        if (devm_add_action_or_reset(dev, pmem_release_disk, pmem))
                return -ENOMEM;

        revalidate_disk(disk);

        pmem->bb_state = sysfs_get_dirent(disk_to_dev(disk)->kobj.sd,
                                          "badblocks");
        if (!pmem->bb_state)
                dev_warn(dev, "'badblocks' notification disabled\n");

        return 0;
}

static int nd_pmem_probe(struct device *dev)
{
        struct nd_namespace_common *ndns;

        ndns = nvdimm_namespace_common_probe(dev);
        if (IS_ERR(ndns))
                return PTR_ERR(ndns);

        if (devm_nsio_enable(dev, to_nd_namespace_io(&ndns->dev)))
                return -ENXIO;

        if (is_nd_btt(dev))
                return nvdimm_namespace_attach_btt(ndns);

        if (is_nd_pfn(dev))
                return pmem_attach_disk(dev, ndns);

        /* if we find a valid info-block we'll come back as that personality */
        if (nd_btt_probe(dev, ndns) == 0 || nd_pfn_probe(dev, ndns) == 0
                        || nd_dax_probe(dev, ndns) == 0)
                return -ENXIO;

        /* ...otherwise we're just a raw pmem device */
        return pmem_attach_disk(dev, ndns);
}

static int nd_pmem_remove(struct device *dev)
{
        struct pmem_device *pmem = dev_get_drvdata(dev);

        if (is_nd_btt(dev))
                nvdimm_namespace_detach_btt(to_nd_btt(dev));
        else {
                /*
                 * Note, this assumes device_lock() context to not race
                 * nd_pmem_notify()
                 */
                sysfs_put(pmem->bb_state);
                pmem->bb_state = NULL;
        }
        nvdimm_flush(to_nd_region(dev->parent));

        return 0;
}

static void nd_pmem_shutdown(struct device *dev)
{
        nvdimm_flush(to_nd_region(dev->parent));
}

static void nd_pmem_notify(struct device *dev, enum nvdimm_event event)
{
        struct nd_region *nd_region;
        resource_size_t offset = 0, end_trunc = 0;
        struct nd_namespace_common *ndns;
        struct nd_namespace_io *nsio;
        struct resource res;
        struct badblocks *bb;
        struct kernfs_node *bb_state;

        if (event != NVDIMM_REVALIDATE_POISON)
                return;

        if (is_nd_btt(dev)) {
                struct nd_btt *nd_btt = to_nd_btt(dev);

                ndns = nd_btt->ndns;
                nd_region = to_nd_region(ndns->dev.parent);
                nsio = to_nd_namespace_io(&ndns->dev);
                bb = &nsio->bb;
                bb_state = NULL;
        } else {
                struct pmem_device *pmem = dev_get_drvdata(dev);

                nd_region = to_region(pmem);
                bb = &pmem->bb;
                bb_state = pmem->bb_state;

                if (is_nd_pfn(dev)) {
                        struct nd_pfn *nd_pfn = to_nd_pfn(dev);
                        struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;

                        ndns = nd_pfn->ndns;
                        offset = pmem->data_offset +
                                        __le32_to_cpu(pfn_sb->start_pad);
                        end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
                } else {
                        ndns = to_ndns(dev);
                }

                nsio = to_nd_namespace_io(&ndns->dev);
        }

        res.start = nsio->res.start + offset;
        res.end = nsio->res.end - end_trunc;
        nvdimm_badblocks_populate(nd_region, bb, &res);
        if (bb_state)
                sysfs_notify_dirent(bb_state);
}

MODULE_ALIAS("pmem");
MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_IO);
MODULE_ALIAS_ND_DEVICE(ND_DEVICE_NAMESPACE_PMEM);
static struct nd_device_driver nd_pmem_driver = {
        .probe = nd_pmem_probe,
        .remove = nd_pmem_remove,
        .notify = nd_pmem_notify,
        .shutdown = nd_pmem_shutdown,
        .drv = {
                .name = "nd_pmem",
        },
        .type = ND_DRIVER_NAMESPACE_IO | ND_DRIVER_NAMESPACE_PMEM,
};

module_nd_driver(nd_pmem_driver);

MODULE_AUTHOR("Ross Zwisler <ross.zwisler@linux.intel.com>");
MODULE_LICENSE("GPL v2");