/*
 * Target driver for EMC CLARiiON AX/CX-series hardware.
 * Based on code from Lars Marowsky-Bree <lmb@suse.de>
 * and Ed Goggin <egoggin@emc.com>.
 *
 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
 * Copyright (C) 2006 Mike Christie
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * 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/slab.h>
#include <linux/module.h>
#include <scsi/scsi.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_dh.h>
#include <scsi/scsi_device.h>

#define CLARIION_NAME                   "emc"

#define CLARIION_TRESPASS_PAGE          0x22
#define CLARIION_BUFFER_SIZE            0xFC
#define CLARIION_TIMEOUT                (60 * HZ)
#define CLARIION_RETRIES                3
#define CLARIION_UNBOUND_LU             -1
#define CLARIION_SP_A                   0
#define CLARIION_SP_B                   1

/* Flags */
#define CLARIION_SHORT_TRESPASS         1
#define CLARIION_HONOR_RESERVATIONS     2

/* LUN states */
#define CLARIION_LUN_UNINITIALIZED      -1
#define CLARIION_LUN_UNBOUND            0
#define CLARIION_LUN_BOUND              1
#define CLARIION_LUN_OWNED              2

static unsigned char long_trespass[] = {
        0, 0, 0, 0, 0, 0, 0, 0,
        CLARIION_TRESPASS_PAGE, /* Page code */
        0x09,                   /* Page length - 2 */
        0x01,                   /* Trespass code */
        0xff, 0xff,             /* Trespass target */
        0, 0, 0, 0, 0, 0        /* Reserved bytes / unknown */
};

static unsigned char short_trespass[] = {
        0, 0, 0, 0,
        CLARIION_TRESPASS_PAGE, /* Page code */
        0x02,                   /* Page length - 2 */
        0x01,                   /* Trespass code */
        0xff,                   /* Trespass target */
};

static const char * lun_state[] =
{
    "not bound",
    "bound",
    "owned",
};

struct clariion_dh_data {
        /*
         * Flags:
         *  CLARIION_SHORT_TRESPASS
         * Use short trespass command (FC-series) or the long version
         * (default for AX/CX CLARiiON arrays).
         *
         *  CLARIION_HONOR_RESERVATIONS
         * Whether or not (default) to honor SCSI reservations when
         * initiating a switch-over.
         */
        unsigned flags;
        /*
         * I/O buffer for both MODE_SELECT and INQUIRY commands.
         */
        unsigned char buffer[CLARIION_BUFFER_SIZE];
        /*
         * LUN state
         */
        int lun_state;
        /*
         * SP Port number
         */
        int port;
        /*
         * which SP (A=0,B=1,UNBOUND=-1) is the default SP for this
         * path's mapped LUN
         */
        int default_sp;
        /*
         * which SP (A=0,B=1,UNBOUND=-1) is the active SP for this
         * path's mapped LUN
         */
        int current_sp;
};

/*
 * Parse MODE_SELECT cmd reply.
 */
static int trespass_endio(struct scsi_device *sdev,
                          struct scsi_sense_hdr *sshdr)
{
        int err = SCSI_DH_IO;

        sdev_printk(KERN_ERR, sdev, "%s: Found valid sense data 0x%2x, "
                    "0x%2x, 0x%2x while sending CLARiiON trespass "
                    "command.\n", CLARIION_NAME, sshdr->sense_key,
                    sshdr->asc, sshdr->ascq);

        if (sshdr->sense_key == 0x05 && sshdr->asc == 0x04 &&
            sshdr->ascq == 0x00) {
                /*
                 * Array based copy in progress -- do not send
                 * mode_select or copy will be aborted mid-stream.
                 */
                sdev_printk(KERN_INFO, sdev, "%s: Array Based Copy in "
                            "progress while sending CLARiiON trespass "
                            "command.\n", CLARIION_NAME);
                err = SCSI_DH_DEV_TEMP_BUSY;
        } else if (sshdr->sense_key == 0x02 && sshdr->asc == 0x04 &&
                   sshdr->ascq == 0x03) {
                /*
                 * LUN Not Ready - Manual Intervention Required
                 * indicates in-progress ucode upgrade (NDU).
                 */
                sdev_printk(KERN_INFO, sdev, "%s: Detected in-progress "
                            "ucode upgrade NDU operation while sending "
                            "CLARiiON trespass command.\n", CLARIION_NAME);
                err = SCSI_DH_DEV_TEMP_BUSY;
        } else
                err = SCSI_DH_DEV_FAILED;
        return err;
}

static int parse_sp_info_reply(struct scsi_device *sdev,
                               struct clariion_dh_data *csdev)
{
        int err = SCSI_DH_OK;

        /* check for in-progress ucode upgrade (NDU) */
        if (csdev->buffer[48] != 0) {
                sdev_printk(KERN_NOTICE, sdev, "%s: Detected in-progress "
                            "ucode upgrade NDU operation while finding "
                            "current active SP.", CLARIION_NAME);
                err = SCSI_DH_DEV_TEMP_BUSY;
                goto out;
        }
        if (csdev->buffer[4] > 2) {
                /* Invalid buffer format */
                sdev_printk(KERN_NOTICE, sdev,
                            "%s: invalid VPD page 0xC0 format\n",
                            CLARIION_NAME);
                err = SCSI_DH_NOSYS;
                goto out;
        }
        switch (csdev->buffer[28] & 0x0f) {
        case 6:
                sdev_printk(KERN_NOTICE, sdev,
                            "%s: ALUA failover mode detected\n",
                            CLARIION_NAME);
                break;
        case 4:
                /* Linux failover */
                break;
        default:
                sdev_printk(KERN_WARNING, sdev,
                            "%s: Invalid failover mode %d\n",
                            CLARIION_NAME, csdev->buffer[28] & 0x0f);
                err = SCSI_DH_NOSYS;
                goto out;
        }

        csdev->default_sp = csdev->buffer[5];
        csdev->lun_state = csdev->buffer[4];
        csdev->current_sp = csdev->buffer[8];
        csdev->port = csdev->buffer[7];
        if (csdev->lun_state == CLARIION_LUN_OWNED)
                sdev->access_state = SCSI_ACCESS_STATE_OPTIMAL;
        else
                sdev->access_state = SCSI_ACCESS_STATE_STANDBY;
        if (csdev->default_sp == csdev->current_sp)
                sdev->access_state |= SCSI_ACCESS_STATE_PREFERRED;
out:
        return err;
}

#define emc_default_str "FC (Legacy)"

static char * parse_sp_model(struct scsi_device *sdev, unsigned char *buffer)
{
        unsigned char len = buffer[4] + 5;
        char *sp_model = NULL;
        unsigned char sp_len, serial_len;

        if (len < 160) {
                sdev_printk(KERN_WARNING, sdev,
                            "%s: Invalid information section length %d\n",
                            CLARIION_NAME, len);
                /* Check for old FC arrays */
                if (!strncmp(buffer + 8, "DGC", 3)) {
                        /* Old FC array, not supporting extended information */
                        sp_model = emc_default_str;
                }
                goto out;
        }

        /*
         * Parse extended information for SP model number
         */
        serial_len = buffer[160];
        if (serial_len == 0 || serial_len + 161 > len) {
                sdev_printk(KERN_WARNING, sdev,
                            "%s: Invalid array serial number length %d\n",
                            CLARIION_NAME, serial_len);
                goto out;
        }
        sp_len = buffer[99];
        if (sp_len == 0 || serial_len + sp_len + 161 > len) {
                sdev_printk(KERN_WARNING, sdev,
                            "%s: Invalid model number length %d\n",
                            CLARIION_NAME, sp_len);
                goto out;
        }
        sp_model = &buffer[serial_len + 161];
        /* Strip whitespace at the end */
        while (sp_len > 1 && sp_model[sp_len - 1] == ' ')
                sp_len--;

        sp_model[sp_len] = '\0';

out:
        return sp_model;
}

static int send_trespass_cmd(struct scsi_device *sdev,
                            struct clariion_dh_data *csdev)
{
        unsigned char *page22;
        unsigned char cdb[COMMAND_SIZE(MODE_SELECT)];
        int err, res = SCSI_DH_OK, len;
        struct scsi_sense_hdr sshdr;
        u64 req_flags = REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT |
                REQ_FAILFAST_DRIVER;

        if (csdev->flags & CLARIION_SHORT_TRESPASS) {
                page22 = short_trespass;
                if (!(csdev->flags & CLARIION_HONOR_RESERVATIONS))
                        /* Set Honor Reservations bit */
                        page22[6] |= 0x80;
                len = sizeof(short_trespass);
                cdb[0] = MODE_SELECT;
                cdb[1] = 0x10;
                cdb[4] = len;
        } else {
                page22 = long_trespass;
                if (!(csdev->flags & CLARIION_HONOR_RESERVATIONS))
                        /* Set Honor Reservations bit */
                        page22[10] |= 0x80;
                len = sizeof(long_trespass);
                cdb[0] = MODE_SELECT_10;
                cdb[8] = len;
        }
        BUG_ON((len > CLARIION_BUFFER_SIZE));
        memcpy(csdev->buffer, page22, len);

        err = scsi_execute(sdev, cdb, DMA_TO_DEVICE, csdev->buffer, len, NULL,
                        &sshdr, CLARIION_TIMEOUT * HZ, CLARIION_RETRIES,
                        req_flags, 0, NULL);
        if (err) {
                if (scsi_sense_valid(&sshdr))
                        res = trespass_endio(sdev, &sshdr);
                else {
                        sdev_printk(KERN_INFO, sdev,
                                    "%s: failed to send MODE SELECT: %x\n",
                                    CLARIION_NAME, err);
                        res = SCSI_DH_IO;
                }
        }

        return res;
}

static int clariion_check_sense(struct scsi_device *sdev,
                                struct scsi_sense_hdr *sense_hdr)
{
        switch (sense_hdr->sense_key) {
        case NOT_READY:
                if (sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x03)
                        /*
                         * LUN Not Ready - Manual Intervention Required
                         * indicates this is a passive path.
                         *
                         * FIXME: However, if this is seen and EVPD C0
                         * indicates that this is due to a NDU in
                         * progress, we should set FAIL_PATH too.
                         * This indicates we might have to do a SCSI
                         * inquiry in the end_io path. Ugh.
                         *
                         * Can return FAILED only when we want the error
                         * recovery process to kick in.
                         */
                        return SUCCESS;
                break;
        case ILLEGAL_REQUEST:
                if (sense_hdr->asc == 0x25 && sense_hdr->ascq == 0x01)
                        /*
                         * An array based copy is in progress. Do not
                         * fail the path, do not bypass to another PG,
                         * do not retry. Fail the IO immediately.
                         * (Actually this is the same conclusion as in
                         * the default handler, but lets make sure.)
                         *
                         * Can return FAILED only when we want the error
                         * recovery process to kick in.
                         */
                        return SUCCESS;
                break;
        case UNIT_ATTENTION:
                if (sense_hdr->asc == 0x29 && sense_hdr->ascq == 0x00)
                        /*
                         * Unit Attention Code. This is the first IO
                         * to the new path, so just retry.
                         */
                        return ADD_TO_MLQUEUE;
                break;
        }

        return SCSI_RETURN_NOT_HANDLED;
}

static int clariion_prep_fn(struct scsi_device *sdev, struct request *req)
{
        struct clariion_dh_data *h = sdev->handler_data;
        int ret = BLKPREP_OK;

        if (h->lun_state != CLARIION_LUN_OWNED) {
                ret = BLKPREP_KILL;
                req->rq_flags |= RQF_QUIET;
        }
        return ret;

}

static int clariion_std_inquiry(struct scsi_device *sdev,
                                struct clariion_dh_data *csdev)
{
        int err = SCSI_DH_OK;
        char *sp_model;

        sp_model = parse_sp_model(sdev, sdev->inquiry);
        if (!sp_model) {
                err = SCSI_DH_DEV_UNSUPP;
                goto out;
        }

        /*
         * FC Series arrays do not support long trespass
         */
        if (!strlen(sp_model) || !strncmp(sp_model, "FC",2))
                csdev->flags |= CLARIION_SHORT_TRESPASS;

        sdev_printk(KERN_INFO, sdev,
                    "%s: detected Clariion %s, flags %x\n",
                    CLARIION_NAME, sp_model, csdev->flags);
out:
        return err;
}

static int clariion_send_inquiry(struct scsi_device *sdev,
                                 struct clariion_dh_data *csdev)
{
        int err = SCSI_DH_IO;

        if (!scsi_get_vpd_page(sdev, 0xC0, csdev->buffer,
                               CLARIION_BUFFER_SIZE))
                err = parse_sp_info_reply(sdev, csdev);

        return err;
}

static int clariion_activate(struct scsi_device *sdev,
                                activate_complete fn, void *data)
{
        struct clariion_dh_data *csdev = sdev->handler_data;
        int result;

        result = clariion_send_inquiry(sdev, csdev);
        if (result != SCSI_DH_OK)
                goto done;

        if (csdev->lun_state == CLARIION_LUN_OWNED)
                goto done;

        result = send_trespass_cmd(sdev, csdev);
        if (result != SCSI_DH_OK)
                goto done;
        sdev_printk(KERN_INFO, sdev,"%s: %s trespass command sent\n",
                    CLARIION_NAME,
                    csdev->flags&CLARIION_SHORT_TRESPASS?"short":"long" );

        /* Update status */
        result = clariion_send_inquiry(sdev, csdev);
        if (result != SCSI_DH_OK)
                goto done;

done:
        sdev_printk(KERN_INFO, sdev,
                    "%s: at SP %c Port %d (%s, default SP %c)\n",
                    CLARIION_NAME, csdev->current_sp + 'A',
                    csdev->port, lun_state[csdev->lun_state],
                    csdev->default_sp + 'A');

        if (fn)
                fn(data, result);
        return 0;
}
/*
 * params - parameters in the following format
 *      "no_of_params\0param1\0param2\0param3\0...\0"
 *      for example, string for 2 parameters with value 10 and 21
 *      is specified as "2\010\021\0".
 */
static int clariion_set_params(struct scsi_device *sdev, const char *params)
{
        struct clariion_dh_data *csdev = sdev->handler_data;
        unsigned int hr = 0, st = 0, argc;
        const char *p = params;
        int result = SCSI_DH_OK;

        if ((sscanf(params, "%u", &argc) != 1) || (argc != 2))
                return -EINVAL;

        while (*p++)
                ;
        if ((sscanf(p, "%u", &st) != 1) || (st > 1))
                return -EINVAL;

        while (*p++)
                ;
        if ((sscanf(p, "%u", &hr) != 1) || (hr > 1))
                return -EINVAL;

        if (st)
                csdev->flags |= CLARIION_SHORT_TRESPASS;
        else
                csdev->flags &= ~CLARIION_SHORT_TRESPASS;

        if (hr)
                csdev->flags |= CLARIION_HONOR_RESERVATIONS;
        else
                csdev->flags &= ~CLARIION_HONOR_RESERVATIONS;

        /*
         * If this path is owned, we have to send a trespass command
         * with the new parameters. If not, simply return. Next trespass
         * command would use the parameters.
         */
        if (csdev->lun_state != CLARIION_LUN_OWNED)
                goto done;

        csdev->lun_state = CLARIION_LUN_UNINITIALIZED;
        result = send_trespass_cmd(sdev, csdev);
        if (result != SCSI_DH_OK)
                goto done;

        /* Update status */
        result = clariion_send_inquiry(sdev, csdev);

done:
        return result;
}

static int clariion_bus_attach(struct scsi_device *sdev)
{
        struct clariion_dh_data *h;
        int err;

        h = kzalloc(sizeof(*h) , GFP_KERNEL);
        if (!h)
                return -ENOMEM;
        h->lun_state = CLARIION_LUN_UNINITIALIZED;
        h->default_sp = CLARIION_UNBOUND_LU;
        h->current_sp = CLARIION_UNBOUND_LU;

        err = clariion_std_inquiry(sdev, h);
        if (err != SCSI_DH_OK)
                goto failed;

        err = clariion_send_inquiry(sdev, h);
        if (err != SCSI_DH_OK)
                goto failed;

        sdev_printk(KERN_INFO, sdev,
                    "%s: connected to SP %c Port %d (%s, default SP %c)\n",
                    CLARIION_NAME, h->current_sp + 'A',
                    h->port, lun_state[h->lun_state],
                    h->default_sp + 'A');

        sdev->handler_data = h;
        return 0;

failed:
        kfree(h);
        return -EINVAL;
}

static void clariion_bus_detach(struct scsi_device *sdev)
{
        kfree(sdev->handler_data);
        sdev->handler_data = NULL;
}

static struct scsi_device_handler clariion_dh = {
        .name           = CLARIION_NAME,
        .module         = THIS_MODULE,
        .attach         = clariion_bus_attach,
        .detach         = clariion_bus_detach,
        .check_sense    = clariion_check_sense,
        .activate       = clariion_activate,
        .prep_fn        = clariion_prep_fn,
        .set_params     = clariion_set_params,
};

static int __init clariion_init(void)
{
        int r;

        r = scsi_register_device_handler(&clariion_dh);
        if (r != 0)
                printk(KERN_ERR "%s: Failed to register scsi device handler.",
                        CLARIION_NAME);
        return r;
}

static void __exit clariion_exit(void)
{
        scsi_unregister_device_handler(&clariion_dh);
}

module_init(clariion_init);
module_exit(clariion_exit);

MODULE_DESCRIPTION("EMC CX/AX/FC-family driver");
MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, Chandra Seetharaman <sekharan@us.ibm.com>");
MODULE_LICENSE("GPL");