/*
   * Copyright(c) 2009 Intel Corporation. All rights reserved.
   *
   * 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.
   *
   * 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.,
   * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Maintained at www.Open-FCoE.org
   */
  
  #include <linux/kernel.h>
  #include <linux/types.h>
  #include <linux/scatterlist.h>
  #include <linux/crc32.h>
  #include <linux/module.h>
  
  #include <scsi/libfc.h>
  #include <scsi/fc_encode.h>
  
  #include "fc_libfc.h"
  
  MODULE_AUTHOR("Open-FCoE.org");
  MODULE_DESCRIPTION("libfc");
  MODULE_LICENSE("GPL v2");
  
  unsigned int fc_debug_logging;
  module_param_named(debug_logging, fc_debug_logging, int, S_IRUGO|S_IWUSR);
  MODULE_PARM_DESC(debug_logging, "a bit mask of logging levels");
  
  DEFINE_MUTEX(fc_prov_mutex);
  static LIST_HEAD(fc_local_ports);
  struct blocking_notifier_head fc_lport_notifier_head =
  		BLOCKING_NOTIFIER_INIT(fc_lport_notifier_head);
  EXPORT_SYMBOL(fc_lport_notifier_head);
  
  /*
   * Providers which primarily send requests and PRLIs.
   */
  struct fc4_prov *fc_active_prov[FC_FC4_PROV_SIZE] = {
  	[0] = &fc_rport_t0_prov,
  	[FC_TYPE_FCP] = &fc_rport_fcp_init,
  };
  
  /*
   * Providers which receive requests.
   */
  struct fc4_prov *fc_passive_prov[FC_FC4_PROV_SIZE] = {
  	[FC_TYPE_ELS] = &fc_lport_els_prov,
  };
  
  /**
   * libfc_init() - Initialize libfc.ko
   */
  static int __init libfc_init(void)
  {
  	int rc = 0;
  
  	rc = fc_setup_fcp();
  	if (rc)
  		return rc;
  
  	rc = fc_setup_exch_mgr();
  	if (rc)
  		goto destroy_pkt_cache;
  
  	rc = fc_setup_rport();
  	if (rc)
  		goto destroy_em;
  
  	return rc;
  destroy_em:
  	fc_destroy_exch_mgr();
  destroy_pkt_cache:
  	fc_destroy_fcp();
  	return rc;
  }
  module_init(libfc_init);
  
  /**
   * libfc_exit() - Tear down libfc.ko
   */
  static void __exit libfc_exit(void)
  {
  	fc_destroy_fcp();
  	fc_destroy_exch_mgr();
  	fc_destroy_rport();
  }
  module_exit(libfc_exit);
  
  /**
   * fc_copy_buffer_to_sglist() - This routine copies the data of a buffer
   *				into a scatter-gather list (SG list).
   *
   * @buf: pointer to the data buffer.
   * @len: the byte-length of the data buffer.
   * @sg: pointer to the pointer of the SG list.
   * @nents: pointer to the remaining number of entries in the SG list.
   * @offset: pointer to the current offset in the SG list.
   * @crc: pointer to the 32-bit crc value.
   *	 If crc is NULL, CRC is not calculated.
   */
  u32 fc_copy_buffer_to_sglist(void *buf, size_t len,
  			     struct scatterlist *sg,
  			     u32 *nents, size_t *offset,
  			     u32 *crc)
  {
  	size_t remaining = len;
  	u32 copy_len = 0;
  
  	while (remaining > 0 && sg) {
  		size_t off, sg_bytes;
  		void *page_addr;
  
  		if (*offset >= sg->length) {
  			/*
  			 * Check for end and drop resources
  			 * from the last iteration.
  			 */
  			if (!(*nents))
  				break;
  			--(*nents);
  			*offset -= sg->length;
  			sg = sg_next(sg);
  			continue;
  		}
  		sg_bytes = min(remaining, sg->length - *offset);
  
  		/*
  		 * The scatterlist item may be bigger than PAGE_SIZE,
  		 * but we are limited to mapping PAGE_SIZE at a time.
  		 */
  		off = *offset + sg->offset;
  		sg_bytes = min(sg_bytes,
  			       (size_t)(PAGE_SIZE - (off & ~PAGE_MASK)));
  		page_addr = kmap_atomic(sg_page(sg) + (off >> PAGE_SHIFT));
  		if (crc)
  			*crc = crc32(*crc, buf, sg_bytes);
  		memcpy((char *)page_addr + (off & ~PAGE_MASK), buf, sg_bytes);
  		kunmap_atomic(page_addr);
  		buf += sg_bytes;
  		*offset += sg_bytes;
  		remaining -= sg_bytes;
  		copy_len += sg_bytes;
  	}
  	return copy_len;
  }
  
  /**
   * fc_fill_hdr() -  fill FC header fields based on request
   * @fp: reply frame containing header to be filled in
   * @in_fp: request frame containing header to use in filling in reply
   * @r_ctl: R_CTL value for header
   * @f_ctl: F_CTL value for header, with 0 pad
   * @seq_cnt: sequence count for the header, ignored if frame has a sequence
   * @parm_offset: parameter / offset value
   */
  void fc_fill_hdr(struct fc_frame *fp, const struct fc_frame *in_fp,
  		 enum fc_rctl r_ctl, u32 f_ctl, u16 seq_cnt, u32 parm_offset)
  {
  	struct fc_frame_header *fh;
  	struct fc_frame_header *in_fh;
  	struct fc_seq *sp;
  	u32 fill;
  
  	fh = __fc_frame_header_get(fp);
  	in_fh = __fc_frame_header_get(in_fp);
  
  	if (f_ctl & FC_FC_END_SEQ) {
  		fill = -fr_len(fp) & 3;
  		if (fill) {
  			/* TODO, this may be a problem with fragmented skb */
  			memset(skb_put(fp_skb(fp), fill), 0, fill);
  			f_ctl |= fill;
  		}
  		fr_eof(fp) = FC_EOF_T;
  	} else {
  		WARN_ON(fr_len(fp) % 4 != 0);	/* no pad to non last frame */
  		fr_eof(fp) = FC_EOF_N;
  	}
  
  	fh->fh_r_ctl = r_ctl;
  	memcpy(fh->fh_d_id, in_fh->fh_s_id, sizeof(fh->fh_d_id));
  	memcpy(fh->fh_s_id, in_fh->fh_d_id, sizeof(fh->fh_s_id));
  	fh->fh_type = in_fh->fh_type;
  	hton24(fh->fh_f_ctl, f_ctl);
  	fh->fh_ox_id = in_fh->fh_ox_id;
  	fh->fh_rx_id = in_fh->fh_rx_id;
  	fh->fh_cs_ctl = 0;
  	fh->fh_df_ctl = 0;
  	fh->fh_parm_offset = htonl(parm_offset);
  
  	sp = fr_seq(in_fp);
  	if (sp) {
  		fr_seq(fp) = sp;
  		fh->fh_seq_id = sp->id;
  		seq_cnt = sp->cnt;
  	} else {
  		fh->fh_seq_id = 0;
  	}
  	fh->fh_seq_cnt = ntohs(seq_cnt);
  	fr_sof(fp) = seq_cnt ? FC_SOF_N3 : FC_SOF_I3;
  	fr_encaps(fp) = fr_encaps(in_fp);
  }
  EXPORT_SYMBOL(fc_fill_hdr);
  
  /**
   * fc_fill_reply_hdr() -  fill FC reply header fields based on request
   * @fp: reply frame containing header to be filled in
   * @in_fp: request frame containing header to use in filling in reply
   * @r_ctl: R_CTL value for reply
   * @parm_offset: parameter / offset value
   */
  void fc_fill_reply_hdr(struct fc_frame *fp, const struct fc_frame *in_fp,
  		       enum fc_rctl r_ctl, u32 parm_offset)
  {
  	struct fc_seq *sp;
  
  	sp = fr_seq(in_fp);
  	if (sp)
  		fr_seq(fp) = fr_dev(in_fp)->tt.seq_start_next(sp);
  	fc_fill_hdr(fp, in_fp, r_ctl, FC_FCTL_RESP, 0, parm_offset);
  }
  EXPORT_SYMBOL(fc_fill_reply_hdr);
  
  /**
   * fc_fc4_conf_lport_params() - Modify "service_params" of specified lport
   * if there is service provider (target provider) registered with libfc
   * for specified "fc_ft_type"
   * @lport: Local port which service_params needs to be modified
   * @type: FC-4 type, such as FC_TYPE_FCP
   */
  void fc_fc4_conf_lport_params(struct fc_lport *lport, enum fc_fh_type type)
  {
  	struct fc4_prov *prov_entry;
  	BUG_ON(type >= FC_FC4_PROV_SIZE);
  	BUG_ON(!lport);
  	prov_entry = fc_passive_prov[type];
  	if (type == FC_TYPE_FCP) {
  		if (prov_entry && prov_entry->recv)
  			lport->service_params |= FCP_SPPF_TARG_FCN;
  	}
  }
  
  void fc_lport_iterate(void (*notify)(struct fc_lport *, void *), void *arg)
  {
  	struct fc_lport *lport;
  
  	mutex_lock(&fc_prov_mutex);
  	list_for_each_entry(lport, &fc_local_ports, lport_list)
  		notify(lport, arg);
  	mutex_unlock(&fc_prov_mutex);
  }
  EXPORT_SYMBOL(fc_lport_iterate);
  
  /**
   * fc_fc4_register_provider() - register FC-4 upper-level provider.
   * @type: FC-4 type, such as FC_TYPE_FCP
   * @prov: structure describing provider including ops vector.
   *
   * Returns 0 on success, negative error otherwise.
   */
  int fc_fc4_register_provider(enum fc_fh_type type, struct fc4_prov *prov)
  {
  	struct fc4_prov **prov_entry;
  	int ret = 0;
  
  	if (type >= FC_FC4_PROV_SIZE)
  		return -EINVAL;
  	mutex_lock(&fc_prov_mutex);
  	prov_entry = (prov->recv ? fc_passive_prov : fc_active_prov) + type;
  	if (*prov_entry)
  		ret = -EBUSY;
  	else
  		*prov_entry = prov;
  	mutex_unlock(&fc_prov_mutex);
  	return ret;
  }
  EXPORT_SYMBOL(fc_fc4_register_provider);
  
  /**
   * fc_fc4_deregister_provider() - deregister FC-4 upper-level provider.
   * @type: FC-4 type, such as FC_TYPE_FCP
   * @prov: structure describing provider including ops vector.
   */
  void fc_fc4_deregister_provider(enum fc_fh_type type, struct fc4_prov *prov)
  {
  	BUG_ON(type >= FC_FC4_PROV_SIZE);
  	mutex_lock(&fc_prov_mutex);
  	if (prov->recv)
  		RCU_INIT_POINTER(fc_passive_prov[type], NULL);
  	else
  		RCU_INIT_POINTER(fc_active_prov[type], NULL);
  	mutex_unlock(&fc_prov_mutex);
  	synchronize_rcu();
  }
  EXPORT_SYMBOL(fc_fc4_deregister_provider);
  
  /**
   * fc_fc4_add_lport() - add new local port to list and run notifiers.
   * @lport:  The new local port.
   */
  void fc_fc4_add_lport(struct fc_lport *lport)
  {
  	mutex_lock(&fc_prov_mutex);
  	list_add_tail(&lport->lport_list, &fc_local_ports);
  	blocking_notifier_call_chain(&fc_lport_notifier_head,
  				     FC_LPORT_EV_ADD, lport);
  	mutex_unlock(&fc_prov_mutex);
  }
  
  /**
   * fc_fc4_del_lport() - remove local port from list and run notifiers.
   * @lport:  The new local port.
   */
  void fc_fc4_del_lport(struct fc_lport *lport)
  {
  	mutex_lock(&fc_prov_mutex);
  	list_del(&lport->lport_list);
  	blocking_notifier_call_chain(&fc_lport_notifier_head,
  				     FC_LPORT_EV_DEL, lport);
  	mutex_unlock(&fc_prov_mutex);
  }