laforge has uploaded this change for review. (
https://gerrit.osmocom.org/c/simtrace2/+/23643 )
Change subject: card_emu: Fix USART timer, particularly in re-start situations
......................................................................
card_emu: Fix USART timer, particularly in re-start situations
The existing code started the timer once (and expired once) but didn't
properly handle re-starting of the timer. Neither did it handle
the 'half time expiration' case. If we want to call a function after
half the WT expiring, we must of course program the hardware for half
the timeout, and not the full timeout...
Change-Id: Ia999d97f835c27597fcd1cf7ac78bac0ab9c98c1
---
M firmware/libcommon/source/mode_cardemu.c
1 file changed, 40 insertions(+), 12 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/simtrace2 refs/changes/43/23643/1
diff --git a/firmware/libcommon/source/mode_cardemu.c
b/firmware/libcommon/source/mode_cardemu.c
index 8531eb5..14f62a6 100644
--- a/firmware/libcommon/source/mode_cardemu.c
+++ b/firmware/libcommon/source/mode_cardemu.c
@@ -212,6 +212,23 @@
return 1;
}
+static uint16_t compute_next_timeout(struct cardem_inst *ci)
+{
+ uint32_t want_to_expire;
+
+ if (ci->wt.total == 0)
+ return 0;
+
+ if (!ci->wt.half_time_notified) {
+ /* we need to make sure to expire after half the total waiting
time */
+ OSMO_ASSERT(ci->wt.remaining > (ci->wt.total / 2));
+ want_to_expire = ci->wt.remaining - (ci->wt.total / 2);
+ } else
+ want_to_expire = ci->wt.remaining;
+ TRACE_INFO("want_to_expire=%u (total=%u, remaining=%u)\r\n",
want_to_expire, ci->wt.total, ci->wt.remaining);
+ /* if value exceeds the USART TO range, use the maximum possible value
for one round */
+ return OSMO_MIN(want_to_expire, 0xffff);
+}
/*! common handler if interrupt was received.
* \param[in] inst_num Instance number, range 0..1 (some boards only '0'
permitted) */
@@ -254,6 +271,9 @@
* how many etu have expired since we last sent a byte. See section
* 33.7.3.11 "Receiver Time-out" of the SAM3S8 Data Sheet */
if (csr & US_CSR_TIMEOUT) {
+ /* clear timeout flag (and stop timeout until next character is
received) */
+ usart->US_CR |= US_CR_STTTO;
+
/* RX has been inactive for some time */
if (ci->wt.remaining <= (usart->US_RTOR & 0xffff)) {
/* waiting time is over; will stop the timer */
@@ -266,17 +286,26 @@
if (ci->wt.remaining == 0) {
/* let the FSM know that WT has expired */
card_emu_wtime_expired(ci->ch);
- } else if (ci->wt.remaining <= ci->wt.total / 2 &&
!ci->wt.half_time_notified) {
- /* let the FS know that half of the WT has expired */
- card_emu_wtime_half_expired(ci->ch);
- ci->wt.half_time_notified = true;
+ /* don't automatically re-start in this case */
+ } else {
+ bool half_time_just_reached = false;
+
+ if (ci->wt.remaining <= ci->wt.total / 2 &&
!ci->wt.half_time_notified) {
+ ci->wt.half_time_notified = true;
+ /* don't immediately call
card_emu_wtime_half_expired(), as that
+ * in turn may calls card_emu_uart_update_wt()
which will change
+ * the timeout but would be overridden 4 lines
below */
+ half_time_just_reached = true;
+ }
+
+ /* update the counter no matter if we reached half time
or not */
+ usart->US_RTOR = compute_next_timeout(ci);
+ /* restart the counter (if wt is 0, the timeout is not
started) */
+ usart->US_CR |= US_CR_RETTO;
+
+ if (half_time_just_reached)
+ card_emu_wtime_half_expired(ci->ch);
}
- /* if value exceeds the USART TO range, use the maximum for now
*/
- usart->US_RTOR = OSMO_MIN(ci->wt.remaining, 0xffff);
- /* clear timeout flag (and stop timeout until next character is
received) */
- usart->US_CR |= US_CR_STTTO;
- /* restart the counter (it wt is 0, the timeout is not started)
*/
- usart->US_CR |= US_CR_RETTO;
}
}
@@ -336,8 +365,7 @@
/* FIXME: guard against race with interrupt handler */
ci->wt.remaining = ci->wt.total;
ci->wt.half_time_notified = false;
- /* if value exceeds the USART TO range, use the maximum for now */
- usart->US_RTOR = OSMO_MIN(ci->wt.remaining, 0xffff);
+ usart->US_RTOR = compute_next_timeout(ci);
/* restart the counter (if wt is 0, the timeout is not started) */
usart->US_CR |= US_CR_RETTO;
}
--
To view, visit https://gerrit.osmocom.org/c/simtrace2/+/23643
To unsubscribe, or for help writing mail filters, visit
https://gerrit.osmocom.org/settings
Gerrit-Project: simtrace2
Gerrit-Branch: master
Gerrit-Change-Id: Ia999d97f835c27597fcd1cf7ac78bac0ab9c98c1
Gerrit-Change-Number: 23643
Gerrit-PatchSet: 1
Gerrit-Owner: laforge <lafo...@osmocom.org>
Gerrit-CC: Jenkins Builder
Gerrit-MessageType: newchange
