lincan/src/read_rtl.c

   1 /**************************************************************************/
   2 /* File: read_rtl.c - RT-Linux variant of read systemcall                 */
   3 /*                                                                        */
   4 /* LinCAN - (Not only) Linux CAN bus driver                               */
   5 /* Copyright (C) 2002-2009 DCE FEE CTU Prague <http://dce.felk.cvut.cz>   */
   6 /* Copyright (C) 2002-2009 Pavel Pisa <pisa@cmp.felk.cvut.cz>             */
   7 /* Funded by OCERA and FRESCOR IST projects                               */
   8 /* Based on CAN driver code by Arnaud Westenberg <arnaud@wanadoo.nl>      */
   9 /*                                                                        */
  10 /* LinCAN is free software; you can redistribute it and/or modify it      */
  11 /* under terms of the GNU General Public License as published by the      */
  12 /* Free Software Foundation; either version 2, or (at your option) any    */
  13 /* later version.  LinCAN is distributed in the hope that it will be      */
  14 /* useful, but WITHOUT ANY WARRANTY; without even the implied warranty    */
  15 /* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU    */
  16 /* General Public License for more details. You should have received a    */
  17 /* copy of the GNU General Public License along with LinCAN; see file     */
  18 /* COPYING. If not, write to the Free Software Foundation, 675 Mass Ave,  */
  19 /* Cambridge, MA 02139, USA.                                              */
  20 /*                                                                        */
  21 /* To allow use of LinCAN in the compact embedded systems firmware        */
  22 /* and RT-executives (RTEMS for example), main authors agree with next    */
  23 /* special exception:                                                     */
  24 /*                                                                        */
  25 /* Including LinCAN header files in a file, instantiating LinCAN generics */
  26 /* or templates, or linking other files with LinCAN objects to produce    */
  27 /* an application image/executable, does not by itself cause the          */
  28 /* resulting application image/executable to be covered by                */
  29 /* the GNU General Public License.                                        */
  30 /* This exception does not however invalidate any other reasons           */
  31 /* why the executable file might be covered by the GNU Public License.    */
  32 /* Publication of enhanced or derived LinCAN files is required although.  */
  33 /**************************************************************************/
  34
  35 #ifdef CAN_WITH_RTL
  36
  37 #include "../include/can.h"
  38 #include "../include/can_sysdep.h"
  39 #include "../include/main.h"
  40
  41 #include <rtl_posixio.h>
  42 #include "../include/can_iortl.h"
  43
  44 /* This is the 'Normal' read handler for normal transmission messages */
  45 static inline
  46 ssize_t can_std_read_rtl(struct canque_ends_t *qends, int nonblock_fl,
  47                         char *buffer, size_t length)
  48 {
  49         int ret;
  50         struct canmsg_t *msg_buff = (struct canmsg_t *)buffer;
  51         int bytes_to_copy;
  52         struct canque_edge_t *qedge;
  53         struct canque_slot_t *slot;
  54
  55         ret=canque_test_outslot(qends, &qedge, &slot);
  56         if(ret<0){
  57                 if (nonblock_fl) {
  58                         return -EAGAIN;
  59                 }
  60                 ret=canque_get_outslot_wait_rtl(qends, &qedge, &slot);
  61                 if(ret<0){
  62                         if (ret==-1) {
  63                                 DEBUGMSG("Rx interrupted\n");
  64                                 return -EINTR;
  65                         }
  66
  67                         return -EIO;
  68                 }
  69         }
  70         *(msg_buff++)=slot->msg;
  71         canque_free_outslot(qends, qedge, slot);
  72         bytes_to_copy = length-sizeof(struct canmsg_t);
  73
  74         while (bytes_to_copy > 0) {
  75                 ret=canque_test_outslot(qends, &qedge, &slot);
  76                 if(ret<0)
  77                         break;
  78                 *(msg_buff++)=slot->msg;
  79                 canque_free_outslot(qends, qedge, slot);
  80                 bytes_to_copy -= sizeof(struct canmsg_t);
  81         }
  82
  83         return length-bytes_to_copy;
  84 }
  85
  86
  87 ssize_t can_read_rtl_posix(struct rtl_file *fptr, char *buffer,
  88                                 size_t length, loff_t *ppos)
  89 {
  90         struct canuser_t *canuser =
  91                 (struct canuser_t *)can_get_rtl_file_private_data(fptr);
  92         struct canque_ends_t *qends;
  93         int      ret;
  94
  95         if(!canuser || (canuser->magic != CAN_USER_MAGIC)){
  96                 CANMSG("can_read_rtl_posix: bad canuser magic\n");
  97                 return -ENODEV;
  98         }
  99
 100         if (length < sizeof(struct canmsg_t)) {
 101                 DEBUGMSG("Trying to read less bytes than a CAN message, \n");
 102                 DEBUGMSG("this will always return zero.\n");
 103                 return 0;
 104         }
 105
 106         qends = canuser->qends;
 107
 108         /*if (((struct canmsg_t *)buffer)->flags & MSG_RTR)
 109                 ret = can_rtr_read(chip, obj, buffer);
 110         else*/
 111                 ret = can_std_read_rtl(qends, fptr->f_flags & O_NONBLOCK,
 112                         buffer, length);
 113
 114         return ret;
 115 }
 116
 117 #endif /*CAN_WITH_RTL*/
 118