lincan/src/read.c

   1 /* read.c
   2  * Linux CAN-bus device driver.
   3  * Written by Arnaud Westenberg email:arnaud@wanadoo.nl
   4  * Rewritten for new CAN queues by Pavel Pisa - OCERA team member
   5  * email:pisa@cmp.felk.cvut.cz
   6  * This software is released under the GPL-License.
   7  * Version lincan-0.2  9 Jul 2003
   8  */
   9
  10 #define __NO_VERSION__
  11 #include <linux/module.h>
  12
  13 #include <linux/autoconf.h>
  14
  15 #include <linux/version.h>
  16 #if (LINUX_VERSION_CODE < KERNEL_VERSION(2,4,0))
  17 #include <linux/malloc.h>
  18 #else
  19 #include <linux/slab.h>
  20 #endif
  21 #include <linux/version.h>
  22 #include <asm/uaccess.h>
  23 #include <asm/irq.h>
  24
  25 #include "../include/main.h"
  26 #include "../include/read.h"
  27 #include "../include/ioctl.h"
  28
  29 /* This is the 'Normal' read handler for normal transmission messages */
  30 inline ssize_t can_std_read(struct file *file, struct canque_ends_t *qends,
  31                         struct msgobj_t *obj, char *buffer, size_t length)
  32 {
  33         int ret;
  34         int bytes_to_copy;
  35         struct canque_edge_t *qedge;
  36         struct canque_slot_t *slot;
  37
  38         ret=canque_test_outslot(qends, &qedge, &slot);
  39         if(ret<0){
  40                 if (file->f_flags & O_NONBLOCK) {
  41                         return -EAGAIN;
  42                 }
  43                 ret=canque_get_outslot_wait_kern(qends, &qedge, &slot);
  44                 if(ret<0){
  45                         if (signal_pending(current)) {
  46                                 DEBUGMSG("Rx interrupted\n");
  47                                 return -EINTR;
  48                         }
  49                         /*if (!can_timeout) {
  50                                 DEBUGMSG("no data received\n");
  51                                 return 0;
  52                         }*/
  53                         return -EIO;
  54                 }
  55         }
  56
  57         copy_to_user(buffer, &slot->msg, sizeof(struct canmsg_t));
  58         canque_free_outslot(qends, qedge, slot);
  59         buffer += sizeof(struct canmsg_t);
  60         bytes_to_copy = length-sizeof(struct canmsg_t);
  61
  62         while (bytes_to_copy > 0) {
  63                 ret=canque_test_outslot(qends, &qedge, &slot);
  64                 if(ret<0)
  65                         break;
  66                 copy_to_user(buffer, &slot->msg, sizeof(struct canmsg_t));
  67                 canque_free_outslot(qends, qedge, slot);
  68                 buffer += sizeof(struct canmsg_t);
  69                 bytes_to_copy -= sizeof(struct canmsg_t);
  70         }
  71
  72         return length-bytes_to_copy;
  73 }
  74
  75 /* This is the 'RTR' read handler for remote transmission request messages */
  76 inline ssize_t can_rtr_read(struct chip_t *chip, struct msgobj_t *obj,
  77                                                                 char *buffer)
  78 {
  79         unsigned long flags;
  80         struct rtr_id *rtr_current, *new_rtr_entry;
  81         struct canmsg_t read_msg;
  82
  83         DEBUGMSG("Remote transmission request\n");
  84         spin_lock_irqsave(&hardware_p->rtr_lock, flags);
  85         if (hardware_p->rtr_queue == NULL) { //No remote messages pending
  86                 new_rtr_entry=(struct rtr_id *)kmalloc(sizeof(struct rtr_id),GFP_ATOMIC);
  87                 if (new_rtr_entry == NULL) {
  88                         spin_unlock_irqrestore(&hardware_p->rtr_lock,
  89                                                                 flags);
  90                         return -ENOMEM;
  91                 }
  92                 hardware_p->rtr_queue=new_rtr_entry;
  93         }
  94         else {
  95                 rtr_current=hardware_p->rtr_queue;
  96                 while (rtr_current->next != NULL)
  97                         rtr_current=rtr_current->next;
  98                 new_rtr_entry=(struct rtr_id *)kmalloc(sizeof(struct rtr_id),GFP_ATOMIC);
  99                 rtr_current->next=new_rtr_entry;
 100         }
 101 #if (LINUX_VERSION_CODE <= KERNEL_VERSION(2,3,0))
 102         init_waitqueue(&new_rtr_entry->rtr_wq);
 103 #else
 104         init_waitqueue_head(&new_rtr_entry->rtr_wq);
 105 #endif
 106         new_rtr_entry->id = read_msg.id;
 107         new_rtr_entry->rtr_message = &read_msg;
 108         new_rtr_entry->next=NULL;
 109
 110         spin_unlock_irqrestore(&hardware_p->rtr_lock, flags);
 111
 112         /* Send remote transmission request */
 113         chip->chipspecops->remote_request(chip,obj);
 114         obj->ret = 0;
 115         interruptible_sleep_on(&new_rtr_entry->rtr_wq);
 116
 117         spin_lock_irqsave(&hardware_p->rtr_lock, flags);
 118         copy_to_user(buffer, &read_msg, sizeof(struct canmsg_t));
 119         if (hardware_p->rtr_queue == new_rtr_entry) {
 120                 if (new_rtr_entry->next != NULL)
 121                         hardware_p->rtr_queue=new_rtr_entry->next;
 122                 else
 123                         hardware_p->rtr_queue=NULL;
 124         }
 125         else {
 126                 rtr_current=hardware_p->rtr_queue;
 127                 while (rtr_current->next != new_rtr_entry)
 128                         rtr_current=rtr_current->next;
 129                 if (new_rtr_entry->next != NULL)
 130                         rtr_current->next=new_rtr_entry->next;
 131                 else
 132                         rtr_current->next=NULL;
 133         }
 134         spin_unlock_irqrestore(&hardware_p->rtr_lock, flags);
 135         kfree(new_rtr_entry);
 136
 137         return obj->ret;
 138 }
 139
 140 ssize_t can_read(struct file *file, char *buffer, size_t length, loff_t *offset)
 141 {
 142         struct canuser_t *canuser = (struct canuser_t*)(file->private_data);
 143         struct msgobj_t *obj;
 144         struct chip_t *chip;
 145         struct canmsg_t read_msg;
 146         struct canque_ends_t *qends;
 147         int ret=0;
 148
 149         if(!canuser || (canuser->magic != CAN_USER_MAGIC)){
 150                 CANMSG("can_close: bad canuser magic\n");
 151                 return -ENODEV;
 152         }
 153
 154         if (length < sizeof(struct canmsg_t)) {
 155                 DEBUGMSG("Trying to read less bytes than a CAN message, \n");
 156                 DEBUGMSG("this will always return zero.\n");
 157                 return 0;
 158         }
 159         if (length > 8 * sizeof(struct canmsg_t)) {
 160                 DEBUGMSG("Reading more than 8 CAN messages, this is not supported.\n");
 161                 DEBUGMSG("Defaulting to 8 messages.\n");
 162                 length = 8 * sizeof(struct canmsg_t);
 163         }
 164         /* Initialize hardware pointers */
 165         obj = canuser->msgobj;
 166         if (obj == NULL) {
 167                 CANMSG("Could not assign buffer structure\n");
 168                 return -1;
 169         }
 170         qends = canuser->qends;
 171         if ( (chip = obj->hostchip) == NULL) {
 172                 CANMSG("Device is not correctly configured,\n");
 173                 CANMSG("please reload the driver.\n");
 174                 return -1;
 175         }
 176
 177         copy_from_user(&read_msg, buffer, sizeof(struct canmsg_t));
 178         if (read_msg.flags & MSG_RTR)
 179                 ret = can_rtr_read(chip, obj, buffer);
 180         else
 181                 ret = can_std_read(file, qends, obj, buffer, length);
 182
 183         return ret;
 184 }
 185
 186