/*******************************************************************************
   * Filename: target_core_ua.c
   *
   * This file contains logic for SPC-3 Unit Attention emulation
   *
   * Copyright (c) 2009,2010 Rising Tide Systems
   * Copyright (c) 2009,2010 Linux-iSCSI.org
   *
   * Nicholas A. Bellinger <nab@kernel.org>
   *
   * 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 of the License, 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; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   *
   ******************************************************************************/

  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <scsi/scsi.h>
  #include <scsi/scsi_cmnd.h>
  
  #include <target/target_core_base.h>
  #include <target/target_core_device.h>
  #include <target/target_core_transport.h>
  #include <target/target_core_fabric_ops.h>
  #include <target/target_core_configfs.h>
  
  #include "target_core_alua.h"
  #include "target_core_hba.h"
  #include "target_core_pr.h"
  #include "target_core_ua.h"
  
  int core_scsi3_ua_check(
  	struct se_cmd *cmd,
  	unsigned char *cdb)
  {
  	struct se_dev_entry *deve;
  	struct se_session *sess = cmd->se_sess;
  	struct se_node_acl *nacl;

  	if (!sess)

  		return 0;
  
  	nacl = sess->se_node_acl;

  	if (!nacl)

  		return 0;
  
  	deve = &nacl->device_list[cmd->orig_fe_lun];

  	if (!atomic_read(&deve->ua_count))

  		return 0;
  	/*
  	 * From sam4r14, section 5.14 Unit attention condition:
  	 *
  	 * a) if an INQUIRY command enters the enabled command state, the
  	 *    device server shall process the INQUIRY command and shall neither
  	 *    report nor clear any unit attention condition;
  	 * b) if a REPORT LUNS command enters the enabled command state, the
  	 *    device server shall process the REPORT LUNS command and shall not
  	 *    report any unit attention condition;
  	 * e) if a REQUEST SENSE command enters the enabled command state while
  	 *    a unit attention condition exists for the SCSI initiator port
  	 *    associated with the I_T nexus on which the REQUEST SENSE command
  	 *    was received, then the device server shall process the command
  	 *    and either:
  	 */
  	switch (cdb[0]) {
  	case INQUIRY:
  	case REPORT_LUNS:
  	case REQUEST_SENSE:
  		return 0;
  	default:

  		return -EINVAL;

  	}

  	return -EINVAL;

  }
  
  int core_scsi3_ua_allocate(
  	struct se_node_acl *nacl,
  	u32 unpacked_lun,
  	u8 asc,
  	u8 ascq)
  {
  	struct se_dev_entry *deve;
  	struct se_ua *ua, *ua_p, *ua_tmp;
  	/*
  	 * PASSTHROUGH OPS
  	 */

  	if (!nacl)

  		return -EINVAL;

  
  	ua = kmem_cache_zalloc(se_ua_cache, GFP_ATOMIC);

  	if (!ua) {
  		pr_err("Unable to allocate struct se_ua
  ");

  		return -ENOMEM;

  	}
  	INIT_LIST_HEAD(&ua->ua_dev_list);
  	INIT_LIST_HEAD(&ua->ua_nacl_list);
  
  	ua->ua_nacl = nacl;
  	ua->ua_asc = asc;
  	ua->ua_ascq = ascq;
  
  	spin_lock_irq(&nacl->device_list_lock);
  	deve = &nacl->device_list[unpacked_lun];
  
  	spin_lock(&deve->ua_lock);
  	list_for_each_entry_safe(ua_p, ua_tmp, &deve->ua_list, ua_nacl_list) {
  		/*
  		 * Do not report the same UNIT ATTENTION twice..
  		 */
  		if ((ua_p->ua_asc == asc) && (ua_p->ua_ascq == ascq)) {
  			spin_unlock(&deve->ua_lock);
  			spin_unlock_irq(&nacl->device_list_lock);
  			kmem_cache_free(se_ua_cache, ua);
  			return 0;
  		}
  		/*
  		 * Attach the highest priority Unit Attention to
  		 * the head of the list following sam4r14,
  		 * Section 5.14 Unit Attention Condition:
  		 *
  		 * POWER ON, RESET, OR BUS DEVICE RESET OCCURRED highest
  		 * POWER ON OCCURRED or
  		 * DEVICE INTERNAL RESET
  		 * SCSI BUS RESET OCCURRED or
  		 * MICROCODE HAS BEEN CHANGED or
  		 * protocol specific
  		 * BUS DEVICE RESET FUNCTION OCCURRED
  		 * I_T NEXUS LOSS OCCURRED
  		 * COMMANDS CLEARED BY POWER LOSS NOTIFICATION
  		 * all others                                    Lowest
  		 *
  		 * Each of the ASCQ codes listed above are defined in
  		 * the 29h ASC family, see spc4r17 Table D.1
  		 */
  		if (ua_p->ua_asc == 0x29) {
  			if ((asc == 0x29) && (ascq > ua_p->ua_ascq))
  				list_add(&ua->ua_nacl_list,
  						&deve->ua_list);
  			else
  				list_add_tail(&ua->ua_nacl_list,
  						&deve->ua_list);
  		} else if (ua_p->ua_asc == 0x2a) {
  			/*
  			 * Incoming Family 29h ASCQ codes will override
  			 * Family 2AHh ASCQ codes for Unit Attention condition.
  			 */
  			if ((asc == 0x29) || (ascq > ua_p->ua_asc))
  				list_add(&ua->ua_nacl_list,
  					&deve->ua_list);
  			else
  				list_add_tail(&ua->ua_nacl_list,
  						&deve->ua_list);
  		} else
  			list_add_tail(&ua->ua_nacl_list,
  				&deve->ua_list);
  		spin_unlock(&deve->ua_lock);
  		spin_unlock_irq(&nacl->device_list_lock);
  
  		atomic_inc(&deve->ua_count);
  		smp_mb__after_atomic_inc();
  		return 0;
  	}
  	list_add_tail(&ua->ua_nacl_list, &deve->ua_list);
  	spin_unlock(&deve->ua_lock);
  	spin_unlock_irq(&nacl->device_list_lock);

  	pr_debug("[%s]: Allocated UNIT ATTENTION, mapped LUN: %u, ASC:"

  		" 0x%02x, ASCQ: 0x%02x
  ",

  		nacl->se_tpg->se_tpg_tfo->get_fabric_name(), unpacked_lun,

  		asc, ascq);
  
  	atomic_inc(&deve->ua_count);
  	smp_mb__after_atomic_inc();
  	return 0;
  }
  
  void core_scsi3_ua_release_all(
  	struct se_dev_entry *deve)
  {
  	struct se_ua *ua, *ua_p;
  
  	spin_lock(&deve->ua_lock);
  	list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
  		list_del(&ua->ua_nacl_list);
  		kmem_cache_free(se_ua_cache, ua);
  
  		atomic_dec(&deve->ua_count);
  		smp_mb__after_atomic_dec();
  	}
  	spin_unlock(&deve->ua_lock);
  }
  
  void core_scsi3_ua_for_check_condition(
  	struct se_cmd *cmd,
  	u8 *asc,
  	u8 *ascq)
  {

  	struct se_device *dev = cmd->se_dev;

  	struct se_dev_entry *deve;
  	struct se_session *sess = cmd->se_sess;
  	struct se_node_acl *nacl;
  	struct se_ua *ua = NULL, *ua_p;
  	int head = 1;

  	if (!sess)

  		return;
  
  	nacl = sess->se_node_acl;

  	if (!nacl)

  		return;
  
  	spin_lock_irq(&nacl->device_list_lock);
  	deve = &nacl->device_list[cmd->orig_fe_lun];

  	if (!atomic_read(&deve->ua_count)) {

  		spin_unlock_irq(&nacl->device_list_lock);
  		return;
  	}
  	/*
  	 * The highest priority Unit Attentions are placed at the head of the
  	 * struct se_dev_entry->ua_list, and will be returned in CHECK_CONDITION +
  	 * sense data for the received CDB.
  	 */
  	spin_lock(&deve->ua_lock);
  	list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
  		/*
  		 * For ua_intlck_ctrl code not equal to 00b, only report the
  		 * highest priority UNIT_ATTENTION and ASC/ASCQ without
  		 * clearing it.
  		 */

  		if (dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl != 0) {

  			*asc = ua->ua_asc;
  			*ascq = ua->ua_ascq;
  			break;
  		}
  		/*
  		 * Otherwise for the default 00b, release the UNIT ATTENTION

  		 * condition.  Return the ASC/ASCQ of the highest priority UA

  		 * (head of the list) in the outgoing CHECK_CONDITION + sense.
  		 */
  		if (head) {
  			*asc = ua->ua_asc;
  			*ascq = ua->ua_ascq;
  			head = 0;
  		}
  		list_del(&ua->ua_nacl_list);
  		kmem_cache_free(se_ua_cache, ua);
  
  		atomic_dec(&deve->ua_count);
  		smp_mb__after_atomic_dec();
  	}
  	spin_unlock(&deve->ua_lock);
  	spin_unlock_irq(&nacl->device_list_lock);

  	pr_debug("[%s]: %s UNIT ATTENTION condition with"

  		" INTLCK_CTRL: %d, mapped LUN: %u, got CDB: 0x%02x"
  		" reported ASC: 0x%02x, ASCQ: 0x%02x
  ",

  		nacl->se_tpg->se_tpg_tfo->get_fabric_name(),
  		(dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl != 0) ? "Reporting" :
  		"Releasing", dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl,

  		cmd->orig_fe_lun, cmd->t_task_cdb[0], *asc, *ascq);

  }
  
  int core_scsi3_ua_clear_for_request_sense(
  	struct se_cmd *cmd,
  	u8 *asc,
  	u8 *ascq)
  {
  	struct se_dev_entry *deve;
  	struct se_session *sess = cmd->se_sess;
  	struct se_node_acl *nacl;
  	struct se_ua *ua = NULL, *ua_p;
  	int head = 1;

  	if (!sess)

  		return -EINVAL;

  
  	nacl = sess->se_node_acl;

  	if (!nacl)

  		return -EINVAL;

  
  	spin_lock_irq(&nacl->device_list_lock);
  	deve = &nacl->device_list[cmd->orig_fe_lun];

  	if (!atomic_read(&deve->ua_count)) {

  		spin_unlock_irq(&nacl->device_list_lock);

  		return -EPERM;

  	}
  	/*
  	 * The highest priority Unit Attentions are placed at the head of the
  	 * struct se_dev_entry->ua_list.  The First (and hence highest priority)
  	 * ASC/ASCQ will be returned in REQUEST_SENSE payload data for the
  	 * matching struct se_lun.
  	 *
  	 * Once the returning ASC/ASCQ values are set, we go ahead and

  	 * release all of the Unit Attention conditions for the associated

  	 * struct se_lun.
  	 */
  	spin_lock(&deve->ua_lock);
  	list_for_each_entry_safe(ua, ua_p, &deve->ua_list, ua_nacl_list) {
  		if (head) {
  			*asc = ua->ua_asc;
  			*ascq = ua->ua_ascq;
  			head = 0;
  		}
  		list_del(&ua->ua_nacl_list);
  		kmem_cache_free(se_ua_cache, ua);
  
  		atomic_dec(&deve->ua_count);
  		smp_mb__after_atomic_dec();
  	}
  	spin_unlock(&deve->ua_lock);
  	spin_unlock_irq(&nacl->device_list_lock);

  	pr_debug("[%s]: Released UNIT ATTENTION condition, mapped"

  		" LUN: %u, got REQUEST_SENSE reported ASC: 0x%02x,"

  		" ASCQ: 0x%02x
  ", nacl->se_tpg->se_tpg_tfo->get_fabric_name(),

  		cmd->orig_fe_lun, *asc, *ascq);

  	return (head) ? -EPERM : 0;

  }