lincan/src/select.c

   1 /**************************************************************************/
   2 /* File: select.c - systemcall to wait for new messages and free Tx slots */
   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 #include "../include/can.h"
  36 #include "../include/can_sysdep.h"
  37 #include "../include/main.h"
  38
  39 #include <linux/poll.h>
  40 #include "../include/select.h"
  41
  42 unsigned int can_poll(struct file *file, poll_table *wait)
  43 {
  44         struct canuser_t *canuser = (struct canuser_t*)(file->private_data);
  45         struct canque_ends_t *qends;
  46         struct msgobj_t *obj;
  47         unsigned int mask = 0;
  48         struct canque_edge_t *edge;
  49         int full=0;
  50         int i;
  51
  52         if(!canuser || (canuser->magic != CAN_USER_MAGIC)){
  53                 CANMSG("can_close: bad canuser magic\n");
  54                 return -ENODEV;
  55         }
  56
  57         obj = canuser->msgobj;
  58         qends = canuser->qends;
  59
  60         if (file->f_mode & FMODE_READ) {
  61                 poll_wait(file, &qends->endinfo.fileinfo.readq, wait);
  62                 for(i=CANQUEUE_PRIO_NR;--i>=0;) {
  63                         if(!list_empty(&qends->active[i]))
  64                                 mask |= POLLIN | POLLRDNORM;
  65                 }
  66         }
  67
  68         if ((file->f_mode & FMODE_WRITE) && !(file->f_flags & O_SYNC)) {
  69                 poll_wait(file, &qends->endinfo.fileinfo.writeq, wait);
  70
  71                 canque_for_each_inedge(qends, edge) {
  72                         if(canque_fifo_test_fl(&edge->fifo,FULL))
  73                                 full=1;
  74                 }
  75
  76                 if(!full)
  77                         mask |= POLLOUT | POLLWRNORM;
  78         }
  79
  80         if ((file->f_mode & FMODE_WRITE) && (file->f_flags & O_SYNC)) {
  81                 poll_wait(file, &qends->endinfo.fileinfo.emptyq, wait);
  82
  83                 canque_for_each_inedge(qends, edge) {
  84                         if(!canque_fifo_test_fl(&edge->fifo,EMPTY))
  85                                 full=1;
  86                 }
  87
  88                 if(!full)
  89                         mask |= POLLOUT | POLLWRNORM;
  90         }
  91         return mask;
  92 }