/*
 * 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 <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.
 * @km_type: dedicated page table slot type for kmap_atomic.
 * @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,
                             enum km_type km_type, 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),
                                        km_type);
                if (crc)
                        *crc = crc32(*crc, buf, sg_bytes);
                memcpy((char *)page_addr + (off & ~PAGE_MASK), buf, sg_bytes);
                kunmap_atomic(page_addr, km_type);
                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_assign_pointer(fc_passive_prov[type], NULL);
        else
                rcu_assign_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);
}