/*
 * sd_dif.c - SCSI Data Integrity Field
 *
 * Copyright (C) 2007, 2008 Oracle Corporation
 * Written by: Martin K. Petersen <martin.petersen@oracle.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 <linux/t10-pi.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_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsicam.h>

#include "sd.h"

/*
 * Configure exchange of protection information between OS and HBA.
 */
void sd_dif_config_host(struct scsi_disk *sdkp)
{
        struct scsi_device *sdp = sdkp->device;
        struct gendisk *disk = sdkp->disk;
        u8 type = sdkp->protection_type;
        struct blk_integrity bi;
        int dif, dix;

        dif = scsi_host_dif_capable(sdp->host, type);
        dix = scsi_host_dix_capable(sdp->host, type);

        if (!dix && scsi_host_dix_capable(sdp->host, 0)) {
                dif = 0; dix = 1;
        }

        if (!dix)
                return;

        memset(&bi, 0, sizeof(bi));

        /* Enable DMA of protection information */
        if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP) {
                if (type == T10_PI_TYPE3_PROTECTION)
                        bi.profile = &t10_pi_type3_ip;
                else
                        bi.profile = &t10_pi_type1_ip;

                bi.flags |= BLK_INTEGRITY_IP_CHECKSUM;
        } else
                if (type == T10_PI_TYPE3_PROTECTION)
                        bi.profile = &t10_pi_type3_crc;
                else
                        bi.profile = &t10_pi_type1_crc;

        bi.tuple_size = sizeof(struct t10_pi_tuple);
        sd_printk(KERN_NOTICE, sdkp,
                  "Enabling DIX %s protection\n", bi.profile->name);

        if (dif && type) {
                bi.flags |= BLK_INTEGRITY_DEVICE_CAPABLE;

                if (!sdkp->ATO)
                        goto out;

                if (type == T10_PI_TYPE3_PROTECTION)
                        bi.tag_size = sizeof(u16) + sizeof(u32);
                else
                        bi.tag_size = sizeof(u16);

                sd_printk(KERN_NOTICE, sdkp, "DIF application tag size %u\n",
                          bi.tag_size);
        }

out:
        blk_integrity_register(disk, &bi);
}

/*
 * The virtual start sector is the one that was originally submitted
 * by the block layer.  Due to partitioning, MD/DM cloning, etc. the
 * actual physical start sector is likely to be different.  Remap
 * protection information to match the physical LBA.
 *
 * From a protocol perspective there's a slight difference between
 * Type 1 and 2.  The latter uses 32-byte CDBs exclusively, and the
 * reference tag is seeded in the CDB.  This gives us the potential to
 * avoid virt->phys remapping during write.  However, at read time we
 * don't know whether the virt sector is the same as when we wrote it
 * (we could be reading from real disk as opposed to MD/DM device.  So
 * we always remap Type 2 making it identical to Type 1.
 *
 * Type 3 does not have a reference tag so no remapping is required.
 */
void sd_dif_prepare(struct scsi_cmnd *scmd)
{
        const int tuple_sz = sizeof(struct t10_pi_tuple);
        struct bio *bio;
        struct scsi_disk *sdkp;
        struct t10_pi_tuple *pi;
        u32 phys, virt;

        sdkp = scsi_disk(scmd->request->rq_disk);

        if (sdkp->protection_type == T10_PI_TYPE3_PROTECTION)
                return;

        phys = scsi_prot_ref_tag(scmd);

        __rq_for_each_bio(bio, scmd->request) {
                struct bio_integrity_payload *bip = bio_integrity(bio);
                struct bio_vec iv;
                struct bvec_iter iter;
                unsigned int j;

                /* Already remapped? */
                if (bip->bip_flags & BIP_MAPPED_INTEGRITY)
                        break;

                virt = bip_get_seed(bip) & 0xffffffff;

                bip_for_each_vec(iv, bip, iter) {
                        pi = kmap_atomic(iv.bv_page) + iv.bv_offset;

                        for (j = 0; j < iv.bv_len; j += tuple_sz, pi++) {

                                if (be32_to_cpu(pi->ref_tag) == virt)
                                        pi->ref_tag = cpu_to_be32(phys);

                                virt++;
                                phys++;
                        }

                        kunmap_atomic(pi);
                }

                bip->bip_flags |= BIP_MAPPED_INTEGRITY;
        }
}

/*
 * Remap physical sector values in the reference tag to the virtual
 * values expected by the block layer.
 */
void sd_dif_complete(struct scsi_cmnd *scmd, unsigned int good_bytes)
{
        const int tuple_sz = sizeof(struct t10_pi_tuple);
        struct scsi_disk *sdkp;
        struct bio *bio;
        struct t10_pi_tuple *pi;
        unsigned int j, intervals;
        u32 phys, virt;

        sdkp = scsi_disk(scmd->request->rq_disk);

        if (sdkp->protection_type == T10_PI_TYPE3_PROTECTION || good_bytes == 0)
                return;

        intervals = good_bytes / scsi_prot_interval(scmd);
        phys = scsi_prot_ref_tag(scmd);

        __rq_for_each_bio(bio, scmd->request) {
                struct bio_integrity_payload *bip = bio_integrity(bio);
                struct bio_vec iv;
                struct bvec_iter iter;

                virt = bip_get_seed(bip) & 0xffffffff;

                bip_for_each_vec(iv, bip, iter) {
                        pi = kmap_atomic(iv.bv_page) + iv.bv_offset;

                        for (j = 0; j < iv.bv_len; j += tuple_sz, pi++) {

                                if (intervals == 0) {
                                        kunmap_atomic(pi);
                                        return;
                                }

                                if (be32_to_cpu(pi->ref_tag) == phys)
                                        pi->ref_tag = cpu_to_be32(virt);

                                virt++;
                                phys++;
                                intervals--;
                        }

                        kunmap_atomic(pi);
                }
        }
}