static int cc2520_csma_tx(u8 * buf, u8 len)
{
int backoff;
if (!csma_enabled) {
return csma_bottom->tx(buf, len);
}
spin_lock_irqsave(&state_sl, flags);
if (csma_state == CC2520_CSMA_IDLE) {
csma_state = CC2520_CSMA_TX;
spin_unlock_irqrestore(&state_sl, flags);
memcpy(cur_tx_buf, buf, len);
cur_tx_len = len;
backoff = cc2520_csma_get_backoff(backoff_min, backoff_max_init);
DBG((KERN_INFO "[cc2520] - waiting %d uS to send.\n", backoff));
cc2520_csma_start_timer(backoff);
}
else {
spin_unlock_irqrestore(&state_sl, flags);
DBG((KERN_INFO "[cc2520] - csma layer busy.\n"));
csma_top->tx_done(-CC2520_TX_BUSY);
}
return 0;
}
static enum hrtimer_restart cc2520_csma_timer_cb(struct hrtimer *timer)
{
ktime_t kt;
int new_backoff;
//printk(KERN_INFO "[cc2520] - csma timer fired. \n");
if (cc2520_radio_is_clear()) {
//printk(KERN_INFO "[cc2520] - channel clear, sending.\n");
csma_bottom->tx(cur_tx_buf, cur_tx_len);
return HRTIMER_NORESTART;
}
else {
spin_lock(&state_sl);
if (csma_state == CC2520_CSMA_TX) {
csma_state = CC2520_CSMA_CONG;
spin_unlock(&state_sl);
new_backoff =
cc2520_csma_get_backoff(backoff_min, backoff_max_cong);
INFO((KERN_INFO "[cc2520] - channel still busy, waiting %d uS\n", new_backoff));
kt=ktime_set(0,1000 * new_backoff);
hrtimer_forward_now(&backoff_timer, kt);
return HRTIMER_RESTART;
}
else {
csma_state = CC2520_CSMA_IDLE;
spin_unlock(&state_sl);
INFO((KERN_INFO "[cc2520] - csma/ca: channel busy. aborting tx\n"));
csma_top->tx_done(-CC2520_TX_BUSY);
return HRTIMER_NORESTART;
}
}
}
static enum hrtimer_restart cc2520_csma_timer_cb(struct hrtimer *timer)
{
ktime_t kt;
int new_backoff;
if (cc2520_radio_is_clear()) {
// NOTE: We can absolutely not send from
// interrupt context, there's a few places
// where we spin lock and assume we can be
// preempted. If we're running in atomic mode
// that promise is broken. We use a work queue.
// The workqueue adds about 30uS of latency.
INIT_WORK(&work, cc2520_csma_wq);
queue_work(wq, &work);
return HRTIMER_NORESTART;
}
else {
spin_lock_irqsave(&state_sl, flags);
if (csma_state == CC2520_CSMA_TX) {
csma_state = CC2520_CSMA_CONG;
spin_unlock_irqrestore(&state_sl, flags);
new_backoff =
cc2520_csma_get_backoff(backoff_min, backoff_max_cong);
INFO((KERN_INFO "[cc2520] - channel still busy, waiting %d uS\n", new_backoff));
kt = ktime_set(0,1000 * new_backoff);
hrtimer_forward_now(&backoff_timer, kt);
return HRTIMER_RESTART;
}
else {
csma_state = CC2520_CSMA_IDLE;
spin_unlock_irqrestore(&state_sl, flags);
csma_top->tx_done(-CC2520_TX_BUSY);
return HRTIMER_NORESTART;
}
}
}
static int cc2520_csma_tx(u8 * buf, u8 len)
{
int backoff;
spin_lock(&state_sl);
if (csma_state == CC2520_CSMA_IDLE) {
csma_state = CC2520_CSMA_TX;
spin_unlock(&state_sl);
memcpy(cur_tx_buf, buf, len);
cur_tx_len = len;
backoff = cc2520_csma_get_backoff(backoff_min, backoff_max_init);
//printk(KERN_INFO "[cc2520] - waiting %d uS to send.\n", backoff);
cc2520_csma_start_timer(backoff);
}
else {
spin_unlock(&state_sl);
csma_top->tx_done(-CC2520_TX_BUSY);
}
return 0;
}
