drivers/scsi/libfc/fc_libfc.c

   1 /*
   2  * Copyright(c) 2009 Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  16  *
  17  * Maintained at www.Open-FCoE.org
  18  */
  19
  20 #include <linux/kernel.h>
  21 #include <linux/types.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/crc32.h>
  24
  25 #include <scsi/libfc.h>
  26
  27 #include "fc_libfc.h"
  28
  29 MODULE_AUTHOR("Open-FCoE.org");
  30 MODULE_DESCRIPTION("libfc");
  31 MODULE_LICENSE("GPL v2");
  32
  33 unsigned int fc_debug_logging;
  34 module_param_named(debug_logging, fc_debug_logging, int, S_IRUGO|S_IWUSR);
  35 MODULE_PARM_DESC(debug_logging, "a bit mask of logging levels");
  36
  37 /**
  38  * libfc_init() - Initialize libfc.ko
  39  */
  40 static int __init libfc_init(void)
  41 {
  42         int rc = 0;
  43
  44         rc = fc_setup_fcp();
  45         if (rc)
  46                 return rc;
  47
  48         rc = fc_setup_exch_mgr();
  49         if (rc)
  50                 goto destroy_pkt_cache;
  51
  52         rc = fc_setup_rport();
  53         if (rc)
  54                 goto destroy_em;
  55
  56         return rc;
  57 destroy_em:
  58         fc_destroy_exch_mgr();
  59 destroy_pkt_cache:
  60         fc_destroy_fcp();
  61         return rc;
  62 }
  63 module_init(libfc_init);
  64
  65 /**
  66  * libfc_exit() - Tear down libfc.ko
  67  */
  68 static void __exit libfc_exit(void)
  69 {
  70         fc_destroy_fcp();
  71         fc_destroy_exch_mgr();
  72         fc_destroy_rport();
  73 }
  74 module_exit(libfc_exit);
  75
  76 /**
  77  * fc_copy_buffer_to_sglist() - This routine copies the data of a buffer
  78  *                              into a scatter-gather list (SG list).
  79  *
  80  * @buf: pointer to the data buffer.
  81  * @len: the byte-length of the data buffer.
  82  * @sg: pointer to the pointer of the SG list.
  83  * @nents: pointer to the remaining number of entries in the SG list.
  84  * @offset: pointer to the current offset in the SG list.
  85  * @km_type: dedicated page table slot type for kmap_atomic.
  86  * @crc: pointer to the 32-bit crc value.
  87  *       If crc is NULL, CRC is not calculated.
  88  */
  89 u32 fc_copy_buffer_to_sglist(void *buf, size_t len,
  90                              struct scatterlist *sg,
  91                              u32 *nents, size_t *offset,
  92                              enum km_type km_type, u32 *crc)
  93 {
  94         size_t remaining = len;
  95         u32 copy_len = 0;
  96
  97         while (remaining > 0 && sg) {
  98                 size_t off, sg_bytes;
  99                 void *page_addr;
 100
 101                 if (*offset >= sg->length) {
 102                         /*
 103                          * Check for end and drop resources
 104                          * from the last iteration.
 105                          */
 106                         if (!(*nents))
 107                                 break;
 108                         --(*nents);
 109                         *offset -= sg->length;
 110                         sg = sg_next(sg);
 111                         continue;
 112                 }
 113                 sg_bytes = min(remaining, sg->length - *offset);
 114
 115                 /*
 116                  * The scatterlist item may be bigger than PAGE_SIZE,
 117                  * but we are limited to mapping PAGE_SIZE at a time.
 118                  */
 119                 off = *offset + sg->offset;
 120                 sg_bytes = min(sg_bytes,
 121                                (size_t)(PAGE_SIZE - (off & ~PAGE_MASK)));
 122                 page_addr = kmap_atomic(sg_page(sg) + (off >> PAGE_SHIFT),
 123                                         km_type);
 124                 if (crc)
 125                         *crc = crc32(*crc, buf, sg_bytes);
 126                 memcpy((char *)page_addr + (off & ~PAGE_MASK), buf, sg_bytes);
 127                 kunmap_atomic(page_addr, km_type);
 128                 buf += sg_bytes;
 129                 *offset += sg_bytes;
 130                 remaining -= sg_bytes;
 131                 copy_len += sg_bytes;
 132         }
 133         return copy_len;
 134 }