+/* read.c
+ * Linux CAN-bus device driver.
+ * Written by Arnaud Westenberg email:arnaud@wanadoo.nl
+ * This software is released under the GPL-License.
+ * Version 0.7 6 Aug 2001
+ */
+
+#include <linux/autoconf.h>
+#if defined (CONFIG_MODVERSIONS) && !defined (MODVERSIONS)
+#define MODVERSIONS
+#endif
+
+#if defined (MODVERSIONS)
+#include <linux/modversions.h>
+#endif
+
+#include <linux/malloc.h>
+#include <linux/version.h>
+#include <asm/uaccess.h>
+#include <asm/irq.h>
+
+#include "../include/main.h"
+#include "../include/read.h"
+#include "../include/ioctl.h"
+
+/* This is the 'Normal' read handler for normal transmission messages */
+inline ssize_t can_std_read(struct file *file, struct canfifo_t *fifo,
+ struct msgobj_t *obj, char *buffer, size_t length)
+{
+ int can_timeout, ret;
+ int bytes_avail = 0, bytes_to_copy = 0;
+
+ cli();
+ if (fifo->rx_readp == fifo->rx_writep) { // Buffer is empty
+ if (file->f_flags & O_NONBLOCK) {
+ sti();
+ return -EAGAIN;
+ }
+ obj->ret = 0;
+ can_timeout = interruptible_sleep_on_timeout(&fifo->readq,
+ CANTIMEOUT);
+ sti();
+ if (signal_pending(current)) {
+ DEBUGMSG("Rx interrupted\n");
+ return -EINTR;
+ }
+ if (!can_timeout) {
+ DEBUGMSG("Rx timeout\n");
+ return -EIO;
+ }
+ if (obj->ret < 0)
+ return obj->ret;
+ }
+ /* Calculate available bytes in the buffer */
+ cli();
+ bytes_avail = ((int)fifo->rx_readp < (int)fifo->rx_writep) ?
+ ((int)fifo->rx_writep - (int)fifo->rx_readp) :
+ ((int)fifo->rx_writep - (int)fifo->rx_readp +
+ (int)fifo->rx_size);
+ sti();
+
+ bytes_to_copy = (length < bytes_avail) ? length : bytes_avail;
+ ret = bytes_to_copy;
+
+ /* Copy the data to user space */
+ while (bytes_to_copy > 0) {
+ copy_to_user(buffer, fifo->rx_readp, sizeof(struct canmsg_t));
+ buffer += sizeof(struct canmsg_t);
+ bytes_to_copy -= sizeof(struct canmsg_t);
+ fifo->rx_readp++;
+ if (fifo->rx_readp >= fifo->buf_rx_entry + MAX_BUF_LENGTH)
+ fifo->rx_readp = fifo->buf_rx_entry;
+ }
+
+ return ret;
+}
+
+/* This is the 'RTR' read handler for remote transmission request messages */
+inline ssize_t can_rtr_read(struct chip_t *chip, struct msgobj_t *obj,
+ char *buffer)
+{
+ unsigned long flags;
+ struct rtr_id *rtr_current, *new_rtr_entry;
+ struct canmsg_t read_msg;
+
+ DEBUGMSG("Remote transmission request\n");
+ spin_lock_irqsave(&hardware_p->rtr_lock, flags);
+ if (hardware_p->rtr_queue == NULL) { //No remote messages pending
+ new_rtr_entry=(struct rtr_id *)kmalloc(sizeof(struct rtr_id),GFP_ATOMIC);
+ if (new_rtr_entry == NULL) {
+ spin_unlock_irqrestore(&hardware_p->rtr_lock,
+ flags);
+ return -ENOMEM;
+ }
+ hardware_p->rtr_queue=new_rtr_entry;
+ }
+ else {
+ rtr_current=hardware_p->rtr_queue;
+ while (rtr_current->next != NULL)
+ rtr_current=rtr_current->next;
+ new_rtr_entry=(struct rtr_id *)kmalloc(sizeof(struct rtr_id),GFP_ATOMIC);
+ rtr_current->next=new_rtr_entry;
+ }
+#if (LINUX_VERSION_CODE <= KERNEL_VERSION(2,2,19))
+ init_waitqueue(&new_rtr_entry->rtr_wq);
+#else
+ init_waitqueue_head(&new_rtr_entry->rtr_wq);
+#endif
+ new_rtr_entry->id = read_msg.id;
+ new_rtr_entry->rtr_message = &read_msg;
+ new_rtr_entry->next=NULL;
+
+ spin_unlock_irqrestore(&hardware_p->rtr_lock, flags);
+
+ /* Send remote transmission request */
+ chip->chipspecops->remote_request(chip,obj);
+ obj->ret = 0;
+ interruptible_sleep_on(&new_rtr_entry->rtr_wq);
+
+ spin_lock_irqsave(&hardware_p->rtr_lock, flags);
+ copy_to_user(buffer, &read_msg, sizeof(struct canmsg_t));
+ if (hardware_p->rtr_queue == new_rtr_entry) {
+ if (new_rtr_entry->next != NULL)
+ hardware_p->rtr_queue=new_rtr_entry->next;
+ else
+ hardware_p->rtr_queue=NULL;
+ }
+ else {
+ rtr_current=hardware_p->rtr_queue;
+ while (rtr_current->next != new_rtr_entry)
+ rtr_current=rtr_current->next;
+ if (new_rtr_entry->next != NULL)
+ rtr_current->next=new_rtr_entry->next;
+ else
+ rtr_current->next=NULL;
+ }
+ spin_unlock_irqrestore(&hardware_p->rtr_lock, flags);
+ kfree(new_rtr_entry);
+
+ return obj->ret;
+}
+
+ssize_t can_read(struct file *file, char *buffer, size_t length, loff_t *offset)
+{
+ struct msgobj_t *obj;
+ struct chip_t *chip;
+ struct canfifo_t *fifo;
+ struct canmsg_t read_msg;
+ int ret=0;
+
+ if (length < sizeof(struct canmsg_t)) {
+ DEBUGMSG("Trying to read less bytes than a CAN message, \n");
+ DEBUGMSG("this will always return zero.\n");
+ return 0;
+ }
+ if (length > 8 * sizeof(struct canmsg_t)) {
+ DEBUGMSG("Reading more than 8 CAN messages, this is not supported.\n");
+ DEBUGMSG("Defaulting to 8 messages.\n");
+ length = 8 * sizeof(struct canmsg_t);
+ }
+ /* Initialize hardware pointers */
+ if ( (obj = objects_p[MINOR_NR]) == NULL) {
+ CANMSG("Could not assign buffer structure\n");
+ return -1;
+ }
+ if ( (chip = obj->hostchip) == NULL) {
+ CANMSG("Device is not correctly configured,\n");
+ CANMSG("please reload the driver.\n");
+ return -1;
+ }
+ if ( (fifo = obj->fifo) == NULL) {
+ CANMSG("Could not assign buffer memory.\n");
+ return -1;
+ }
+
+ copy_from_user(&read_msg, buffer, sizeof(struct canmsg_t));
+ if (read_msg.flags & MSG_RTR)
+ ret = can_rtr_read(chip, obj, buffer);
+ else
+ ret = can_std_read(file, fifo, obj, buffer, length);
+
+ return ret;
+}
+
+
projects / lincan.git / blobdiff