/*
 * SCSI Zoned Block commands
 *
 * Copyright (C) 2014-2015 SUSE Linux GmbH
 * Written by: Hannes Reinecke <hare@suse.de>
 * Modified by: Damien Le Moal <damien.lemoal@hgst.com>
 * Modified by: Shaun Tancheff <shaun.tancheff@seagate.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
 * USA.
 *
 */

#include <linux/blkdev.h>

#include <asm/unaligned.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_eh.h>

#include "sd.h"
#include "scsi_priv.h"

enum zbc_zone_type {
        ZBC_ZONE_TYPE_CONV = 0x1,
        ZBC_ZONE_TYPE_SEQWRITE_REQ,
        ZBC_ZONE_TYPE_SEQWRITE_PREF,
        ZBC_ZONE_TYPE_RESERVED,
};

enum zbc_zone_cond {
        ZBC_ZONE_COND_NO_WP,
        ZBC_ZONE_COND_EMPTY,
        ZBC_ZONE_COND_IMP_OPEN,
        ZBC_ZONE_COND_EXP_OPEN,
        ZBC_ZONE_COND_CLOSED,
        ZBC_ZONE_COND_READONLY = 0xd,
        ZBC_ZONE_COND_FULL,
        ZBC_ZONE_COND_OFFLINE,
};

/**
 * Convert a zone descriptor to a zone struct.
 */
static void sd_zbc_parse_report(struct scsi_disk *sdkp,
                                u8 *buf,
                                struct blk_zone *zone)
{
        struct scsi_device *sdp = sdkp->device;

        memset(zone, 0, sizeof(struct blk_zone));

        zone->type = buf[0] & 0x0f;
        zone->cond = (buf[1] >> 4) & 0xf;
        if (buf[1] & 0x01)
                zone->reset = 1;
        if (buf[1] & 0x02)
                zone->non_seq = 1;

        zone->len = logical_to_sectors(sdp, get_unaligned_be64(&buf[8]));
        zone->start = logical_to_sectors(sdp, get_unaligned_be64(&buf[16]));
        zone->wp = logical_to_sectors(sdp, get_unaligned_be64(&buf[24]));
        if (zone->type != ZBC_ZONE_TYPE_CONV &&
            zone->cond == ZBC_ZONE_COND_FULL)
                zone->wp = zone->start + zone->len;
}

/**
 * Issue a REPORT ZONES scsi command.
 */
static int sd_zbc_report_zones(struct scsi_disk *sdkp, unsigned char *buf,
                               unsigned int buflen, sector_t lba)
{
        struct scsi_device *sdp = sdkp->device;
        const int timeout = sdp->request_queue->rq_timeout;
        struct scsi_sense_hdr sshdr;
        unsigned char cmd[16];
        unsigned int rep_len;
        int result;

        memset(cmd, 0, 16);
        cmd[0] = ZBC_IN;
        cmd[1] = ZI_REPORT_ZONES;
        put_unaligned_be64(lba, &cmd[2]);
        put_unaligned_be32(buflen, &cmd[10]);
        memset(buf, 0, buflen);

        result = scsi_execute_req(sdp, cmd, DMA_FROM_DEVICE,
                                  buf, buflen, &sshdr,
                                  timeout, SD_MAX_RETRIES, NULL);
        if (result) {
                sd_printk(KERN_ERR, sdkp,
                          "REPORT ZONES lba %llu failed with %d/%d\n",
                          (unsigned long long)lba,
                          host_byte(result), driver_byte(result));
                return -EIO;
        }

        rep_len = get_unaligned_be32(&buf[0]);
        if (rep_len < 64) {
                sd_printk(KERN_ERR, sdkp,
                          "REPORT ZONES report invalid length %u\n",
                          rep_len);
                return -EIO;
        }

        return 0;
}

int sd_zbc_setup_report_cmnd(struct scsi_cmnd *cmd)
{
        struct request *rq = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        sector_t lba, sector = blk_rq_pos(rq);
        unsigned int nr_bytes = blk_rq_bytes(rq);
        int ret;

        WARN_ON(nr_bytes == 0);

        if (!sd_is_zoned(sdkp))
                /* Not a zoned device */
                return BLKPREP_KILL;

        ret = scsi_init_io(cmd);
        if (ret != BLKPREP_OK)
                return ret;

        cmd->cmd_len = 16;
        memset(cmd->cmnd, 0, cmd->cmd_len);
        cmd->cmnd[0] = ZBC_IN;
        cmd->cmnd[1] = ZI_REPORT_ZONES;
        lba = sectors_to_logical(sdkp->device, sector);
        put_unaligned_be64(lba, &cmd->cmnd[2]);
        put_unaligned_be32(nr_bytes, &cmd->cmnd[10]);
        /* Do partial report for speeding things up */
        cmd->cmnd[14] = ZBC_REPORT_ZONE_PARTIAL;

        cmd->sc_data_direction = DMA_FROM_DEVICE;
        cmd->sdb.length = nr_bytes;
        cmd->transfersize = sdkp->device->sector_size;
        cmd->allowed = 0;

        /*
         * Report may return less bytes than requested. Make sure
         * to report completion on the entire initial request.
         */
        rq->__data_len = nr_bytes;

        return BLKPREP_OK;
}

static void sd_zbc_report_zones_complete(struct scsi_cmnd *scmd,
                                         unsigned int good_bytes)
{
        struct request *rq = scmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        struct sg_mapping_iter miter;
        struct blk_zone_report_hdr hdr;
        struct blk_zone zone;
        unsigned int offset, bytes = 0;
        unsigned long flags;
        u8 *buf;

        if (good_bytes < 64)
                return;

        memset(&hdr, 0, sizeof(struct blk_zone_report_hdr));

        sg_miter_start(&miter, scsi_sglist(scmd), scsi_sg_count(scmd),
                       SG_MITER_TO_SG | SG_MITER_ATOMIC);

        local_irq_save(flags);
        while (sg_miter_next(&miter) && bytes < good_bytes) {

                buf = miter.addr;
                offset = 0;

                if (bytes == 0) {
                        /* Set the report header */
                        hdr.nr_zones = min_t(unsigned int,
                                         (good_bytes - 64) / 64,
                                         get_unaligned_be32(&buf[0]) / 64);
                        memcpy(buf, &hdr, sizeof(struct blk_zone_report_hdr));
                        offset += 64;
                        bytes += 64;
                }

                /* Parse zone descriptors */
                while (offset < miter.length && hdr.nr_zones) {
                        WARN_ON(offset > miter.length);
                        buf = miter.addr + offset;
                        sd_zbc_parse_report(sdkp, buf, &zone);
                        memcpy(buf, &zone, sizeof(struct blk_zone));
                        offset += 64;
                        bytes += 64;
                        hdr.nr_zones--;
                }

                if (!hdr.nr_zones)
                        break;

        }
        sg_miter_stop(&miter);
        local_irq_restore(flags);
}

static inline sector_t sd_zbc_zone_sectors(struct scsi_disk *sdkp)
{
        return logical_to_sectors(sdkp->device, sdkp->zone_blocks);
}

static inline unsigned int sd_zbc_zone_no(struct scsi_disk *sdkp,
                                          sector_t sector)
{
        return sectors_to_logical(sdkp->device, sector) >> sdkp->zone_shift;
}

int sd_zbc_setup_reset_cmnd(struct scsi_cmnd *cmd)
{
        struct request *rq = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        sector_t sector = blk_rq_pos(rq);
        sector_t block = sectors_to_logical(sdkp->device, sector);

        if (!sd_is_zoned(sdkp))
                /* Not a zoned device */
                return BLKPREP_KILL;

        if (sdkp->device->changed)
                return BLKPREP_KILL;

        if (sector & (sd_zbc_zone_sectors(sdkp) - 1))
                /* Unaligned request */
                return BLKPREP_KILL;

        cmd->cmd_len = 16;
        memset(cmd->cmnd, 0, cmd->cmd_len);
        cmd->cmnd[0] = ZBC_OUT;
        cmd->cmnd[1] = ZO_RESET_WRITE_POINTER;
        put_unaligned_be64(block, &cmd->cmnd[2]);

        rq->timeout = SD_TIMEOUT;
        cmd->sc_data_direction = DMA_NONE;
        cmd->transfersize = 0;
        cmd->allowed = 0;

        return BLKPREP_OK;
}

int sd_zbc_write_lock_zone(struct scsi_cmnd *cmd)
{
        struct request *rq = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);
        sector_t sector = blk_rq_pos(rq);
        sector_t zone_sectors = sd_zbc_zone_sectors(sdkp);
        unsigned int zno = sd_zbc_zone_no(sdkp, sector);

        /*
         * Note: Checks of the alignment of the write command on
         * logical blocks is done in sd.c
         */

        /* Do not allow zone boundaries crossing on host-managed drives */
        if (blk_queue_zoned_model(sdkp->disk->queue) == BLK_ZONED_HM &&
            (sector & (zone_sectors - 1)) + blk_rq_sectors(rq) > zone_sectors)
                return BLKPREP_KILL;

        /*
         * Do not issue more than one write at a time per
         * zone. This solves write ordering problems due to
         * the unlocking of the request queue in the dispatch
         * path in the non scsi-mq case. For scsi-mq, this
         * also avoids potential write reordering when multiple
         * threads running on different CPUs write to the same
         * zone (with a synchronized sequential pattern).
         */
        if (sdkp->zones_wlock &&
            test_and_set_bit(zno, sdkp->zones_wlock))
                return BLKPREP_DEFER;

        WARN_ON_ONCE(cmd->flags & SCMD_ZONE_WRITE_LOCK);
        cmd->flags |= SCMD_ZONE_WRITE_LOCK;

        return BLKPREP_OK;
}

void sd_zbc_write_unlock_zone(struct scsi_cmnd *cmd)
{
        struct request *rq = cmd->request;
        struct scsi_disk *sdkp = scsi_disk(rq->rq_disk);

        if (sdkp->zones_wlock && cmd->flags & SCMD_ZONE_WRITE_LOCK) {
                unsigned int zno = sd_zbc_zone_no(sdkp, blk_rq_pos(rq));
                WARN_ON_ONCE(!test_bit(zno, sdkp->zones_wlock));
                cmd->flags &= ~SCMD_ZONE_WRITE_LOCK;
                clear_bit_unlock(zno, sdkp->zones_wlock);
                smp_mb__after_atomic();
        }
}

void sd_zbc_complete(struct scsi_cmnd *cmd,
                     unsigned int good_bytes,
                     struct scsi_sense_hdr *sshdr)
{
        int result = cmd->result;
        struct request *rq = cmd->request;

        switch (req_op(rq)) {
        case REQ_OP_ZONE_RESET:

                if (result &&
                    sshdr->sense_key == ILLEGAL_REQUEST &&
                    sshdr->asc == 0x24)
                        /*
                         * INVALID FIELD IN CDB error: reset of a conventional
                         * zone was attempted. Nothing to worry about, so be
                         * quiet about the error.
                         */
                        rq->rq_flags |= RQF_QUIET;
                break;

        case REQ_OP_WRITE:
        case REQ_OP_WRITE_ZEROES:
        case REQ_OP_WRITE_SAME:

                if (result &&
                    sshdr->sense_key == ILLEGAL_REQUEST &&
                    sshdr->asc == 0x21)
                        /*
                         * INVALID ADDRESS FOR WRITE error: It is unlikely that
                         * retrying write requests failed with any kind of
                         * alignement error will result in success. So don't.
                         */
                        cmd->allowed = 0;
                break;

        case REQ_OP_ZONE_REPORT:

                if (!result)
                        sd_zbc_report_zones_complete(cmd, good_bytes);
                break;

        }
}

/**
 * Read zoned block device characteristics (VPD page B6).
 */
static int sd_zbc_read_zoned_characteristics(struct scsi_disk *sdkp,
                                             unsigned char *buf)
{

        if (scsi_get_vpd_page(sdkp->device, 0xb6, buf, 64)) {
                sd_printk(KERN_NOTICE, sdkp,
                          "Unconstrained-read check failed\n");
                return -ENODEV;
        }

        if (sdkp->device->type != TYPE_ZBC) {
                /* Host-aware */
                sdkp->urswrz = 1;
                sdkp->zones_optimal_open = get_unaligned_be64(&buf[8]);
                sdkp->zones_optimal_nonseq = get_unaligned_be64(&buf[12]);
                sdkp->zones_max_open = 0;
        } else {
                /* Host-managed */
                sdkp->urswrz = buf[4] & 1;
                sdkp->zones_optimal_open = 0;
                sdkp->zones_optimal_nonseq = 0;
                sdkp->zones_max_open = get_unaligned_be64(&buf[16]);
        }

        return 0;
}

/**
 * Check reported capacity.
 */
static int sd_zbc_check_capacity(struct scsi_disk *sdkp,
                                 unsigned char *buf)
{
        sector_t lba;
        int ret;

        if (sdkp->rc_basis != 0)
                return 0;

        /* Do a report zone to get the maximum LBA to check capacity */
        ret = sd_zbc_report_zones(sdkp, buf, SD_BUF_SIZE, 0);
        if (ret)
                return ret;

        /* The max_lba field is the capacity of this device */
        lba = get_unaligned_be64(&buf[8]);
        if (lba + 1 == sdkp->capacity)
                return 0;

        if (sdkp->first_scan)
                sd_printk(KERN_WARNING, sdkp,
                          "Changing capacity from %llu to max LBA+1 %llu\n",
                          (unsigned long long)sdkp->capacity,
                          (unsigned long long)lba + 1);
        sdkp->capacity = lba + 1;

        return 0;
}

#define SD_ZBC_BUF_SIZE 131072

static int sd_zbc_check_zone_size(struct scsi_disk *sdkp)
{
        u64 zone_blocks;
        sector_t block = 0;
        unsigned char *buf;
        unsigned char *rec;
        unsigned int buf_len;
        unsigned int list_length;
        int ret;
        u8 same;

        sdkp->zone_blocks = 0;

        /* Get a buffer */
        buf = kmalloc(SD_ZBC_BUF_SIZE, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /* Do a report zone to get the same field */
        ret = sd_zbc_report_zones(sdkp, buf, SD_ZBC_BUF_SIZE, 0);
        if (ret) {
                zone_blocks = 0;
                goto out;
        }

        same = buf[4] & 0x0f;
        if (same > 0) {
                rec = &buf[64];
                zone_blocks = get_unaligned_be64(&rec[8]);
                goto out;
        }

        /*
         * Check the size of all zones: all zones must be of
         * equal size, except the last zone which can be smaller
         * than other zones.
         */
        do {

                /* Parse REPORT ZONES header */
                list_length = get_unaligned_be32(&buf[0]) + 64;
                rec = buf + 64;
                if (list_length < SD_ZBC_BUF_SIZE)
                        buf_len = list_length;
                else
                        buf_len = SD_ZBC_BUF_SIZE;

                /* Parse zone descriptors */
                while (rec < buf + buf_len) {
                        zone_blocks = get_unaligned_be64(&rec[8]);
                        if (sdkp->zone_blocks == 0) {
                                sdkp->zone_blocks = zone_blocks;
                        } else if (zone_blocks != sdkp->zone_blocks &&
                                   (block + zone_blocks < sdkp->capacity
                                    || zone_blocks > sdkp->zone_blocks)) {
                                zone_blocks = 0;
                                goto out;
                        }
                        block += zone_blocks;
                        rec += 64;
                }

                if (block < sdkp->capacity) {
                        ret = sd_zbc_report_zones(sdkp, buf,
                                                  SD_ZBC_BUF_SIZE, block);
                        if (ret)
                                return ret;
                }

        } while (block < sdkp->capacity);

        zone_blocks = sdkp->zone_blocks;

out:
        kfree(buf);

        if (!zone_blocks) {
                if (sdkp->first_scan)
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Devices with non constant zone "
                                  "size are not supported\n");
                return -ENODEV;
        }

        if (!is_power_of_2(zone_blocks)) {
                if (sdkp->first_scan)
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Devices with non power of 2 zone "
                                  "size are not supported\n");
                return -ENODEV;
        }

        if (logical_to_sectors(sdkp->device, zone_blocks) > UINT_MAX) {
                if (sdkp->first_scan)
                        sd_printk(KERN_NOTICE, sdkp,
                                  "Zone size too large\n");
                return -ENODEV;
        }

        sdkp->zone_blocks = zone_blocks;

        return 0;
}

static int sd_zbc_setup(struct scsi_disk *sdkp)
{

        /* chunk_sectors indicates the zone size */
        blk_queue_chunk_sectors(sdkp->disk->queue,
                        logical_to_sectors(sdkp->device, sdkp->zone_blocks));
        sdkp->zone_shift = ilog2(sdkp->zone_blocks);
        sdkp->nr_zones = sdkp->capacity >> sdkp->zone_shift;
        if (sdkp->capacity & (sdkp->zone_blocks - 1))
                sdkp->nr_zones++;

        if (!sdkp->zones_wlock) {
                sdkp->zones_wlock = kcalloc(BITS_TO_LONGS(sdkp->nr_zones),
                                            sizeof(unsigned long),
                                            GFP_KERNEL);
                if (!sdkp->zones_wlock)
                        return -ENOMEM;
        }

        return 0;
}

int sd_zbc_read_zones(struct scsi_disk *sdkp,
                      unsigned char *buf)
{
        int ret;

        if (!sd_is_zoned(sdkp))
                /*
                 * Device managed or normal SCSI disk,
                 * no special handling required
                 */
                return 0;


        /* Get zoned block device characteristics */
        ret = sd_zbc_read_zoned_characteristics(sdkp, buf);
        if (ret)
                goto err;

        /*
         * Check for unconstrained reads: host-managed devices with
         * constrained reads (drives failing read after write pointer)
         * are not supported.
         */
        if (!sdkp->urswrz) {
                if (sdkp->first_scan)
                        sd_printk(KERN_NOTICE, sdkp,
                          "constrained reads devices are not supported\n");
                ret = -ENODEV;
                goto err;
        }

        /* Check capacity */
        ret = sd_zbc_check_capacity(sdkp, buf);
        if (ret)
                goto err;

        /*
         * Check zone size: only devices with a constant zone size (except
         * an eventual last runt zone) that is a power of 2 are supported.
         */
        ret = sd_zbc_check_zone_size(sdkp);
        if (ret)
                goto err;

        /* The drive satisfies the kernel restrictions: set it up */
        ret = sd_zbc_setup(sdkp);
        if (ret)
                goto err;

        /* READ16/WRITE16 is mandatory for ZBC disks */
        sdkp->device->use_16_for_rw = 1;
        sdkp->device->use_10_for_rw = 0;

        return 0;

err:
        sdkp->capacity = 0;

        return ret;
}

void sd_zbc_remove(struct scsi_disk *sdkp)
{
        kfree(sdkp->zones_wlock);
        sdkp->zones_wlock = NULL;
}

void sd_zbc_print_zones(struct scsi_disk *sdkp)
{
        if (!sd_is_zoned(sdkp) || !sdkp->capacity)
                return;

        if (sdkp->capacity & (sdkp->zone_blocks - 1))
                sd_printk(KERN_NOTICE, sdkp,
                          "%u zones of %u logical blocks + 1 runt zone\n",
                          sdkp->nr_zones - 1,
                          sdkp->zone_blocks);
        else
                sd_printk(KERN_NOTICE, sdkp,
                          "%u zones of %u logical blocks\n",
                          sdkp->nr_zones,
                          sdkp->zone_blocks);
}