From 8bcde2e40fd64df9347344dec1b311994850b0e4 Mon Sep 17 00:00:00 2001
From: Adam Dunkels <adam@thingsquare.com>
Date: Wed, 2 Sep 2015 12:05:47 +0200
Subject: [PATCH] Tickless bugfixes:

* The clock interrupt must be scheduled relative to the last interrupt, not relative to the current time (which may have progressed significantly)
* clock_time() must increase continuously, so that code that may be spinning around clock_time() will make progress, not only after each interrupt
---
 cpu/cc26xx-cc13xx/clock.c       | 36 ++++++++++++++++++---------------
 cpu/cc26xx-cc13xx/dev/soc-rtc.c | 10 +++++++++
 cpu/cc26xx-cc13xx/dev/soc-rtc.h |  2 ++
 cpu/cc26xx-cc13xx/lpm.c         |  2 +-
 4 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/cpu/cc26xx-cc13xx/clock.c b/cpu/cc26xx-cc13xx/clock.c
index fd8165d0d..4f6df056f 100644
--- a/cpu/cc26xx-cc13xx/clock.c
+++ b/cpu/cc26xx-cc13xx/clock.c
@@ -120,31 +120,35 @@ clock_init(void)
         ((TIMER_CFG_B_ONE_SHOT >> 8) & 0xFF) | GPT_TBMR_TBPWMIE;
 }
 /*---------------------------------------------------------------------------*/
+static void
+update_clock_variable(void)
+{
+  uint32_t aon_rtc_secs_now;
+  uint32_t aon_rtc_secs_now2;
+  uint16_t aon_rtc_ticks_now;
+
+  do {
+    aon_rtc_secs_now = HWREG(AON_RTC_BASE + AON_RTC_O_SEC);
+    aon_rtc_ticks_now = HWREG(AON_RTC_BASE + AON_RTC_O_SUBSEC) >> 16;
+    aon_rtc_secs_now2 = HWREG(AON_RTC_BASE + AON_RTC_O_SEC);
+  } while(aon_rtc_secs_now != aon_rtc_secs_now2);
+
+  /* Convert AON RTC ticks to clock tick counter */
+  count = (aon_rtc_secs_now * CLOCK_SECOND) + (aon_rtc_ticks_now >> 9);
+}
+/*---------------------------------------------------------------------------*/
 CCIF clock_time_t
 clock_time(void)
 {
+  update_clock_variable();
+
   return (clock_time_t)(count & 0xFFFFFFFF);
 }
 /*---------------------------------------------------------------------------*/
 void
 clock_update(void)
 {
-  bool interrupts_disabled;
-  uint32_t aon_rtc_secs_now;
-  uint16_t aon_rtc_ticks_now;
-
-  interrupts_disabled = ti_lib_int_master_disable();
-
-  aon_rtc_secs_now = HWREG(AON_RTC_BASE + AON_RTC_O_SEC);
-  aon_rtc_ticks_now = HWREG(AON_RTC_BASE + AON_RTC_O_SUBSEC) >> 16;
-
-  /* Convert AON RTC ticks to clock tick counter */
-  count = (aon_rtc_secs_now * CLOCK_SECOND) + (aon_rtc_ticks_now >> 9);
-
-  /* Re-enable interrupts */
-  if(!interrupts_disabled) {
-    ti_lib_int_master_enable();
-  }
+  update_clock_variable();
 
   if(etimer_pending()) {
     etimer_request_poll();
diff --git a/cpu/cc26xx-cc13xx/dev/soc-rtc.c b/cpu/cc26xx-cc13xx/dev/soc-rtc.c
index 16a967b9d..fb5394947 100644
--- a/cpu/cc26xx-cc13xx/dev/soc-rtc.c
+++ b/cpu/cc26xx-cc13xx/dev/soc-rtc.c
@@ -50,6 +50,8 @@
 /*---------------------------------------------------------------------------*/
 /* Prototype of a function in clock.c. Called every time the handler fires */
 void clock_update(void);
+
+static rtimer_clock_t last_isr_time;
 /*---------------------------------------------------------------------------*/
 #define COMPARE_INCREMENT (RTIMER_SECOND / CLOCK_SECOND)
 #define MULTIPLE_512_MASK 0xFFFFFE00
@@ -130,6 +132,12 @@ soc_rtc_schedule_one_shot(uint32_t channel, uint32_t ticks)
   ti_lib_aon_rtc_channel_enable(channel);
 }
 /*---------------------------------------------------------------------------*/
+rtimer_clock_t
+soc_rtc_last_isr_time(void)
+{
+  return last_isr_time;
+}
+/*---------------------------------------------------------------------------*/
 /* The AON RTC interrupt handler */
 void
 soc_rtc_isr(void)
@@ -138,6 +146,8 @@ soc_rtc_isr(void)
 
   ENERGEST_ON(ENERGEST_TYPE_IRQ);
 
+  last_isr_time = RTIMER_NOW();
+
   now = ti_lib_aon_rtc_current_compare_value_get();
 
   /* Adjust the s/w tick counter irrespective of which event trigger this */
diff --git a/cpu/cc26xx-cc13xx/dev/soc-rtc.h b/cpu/cc26xx-cc13xx/dev/soc-rtc.h
index ff6a266ff..cedf318c5 100644
--- a/cpu/cc26xx-cc13xx/dev/soc-rtc.h
+++ b/cpu/cc26xx-cc13xx/dev/soc-rtc.h
@@ -92,6 +92,8 @@ rtimer_clock_t soc_rtc_get_next_trigger(void);
  * instead use Contiki's timer-related libraries
  */
 void soc_rtc_schedule_one_shot(uint32_t channel, uint32_t t);
+
+rtimer_clock_t soc_rtc_last_isr_time(void);
 /*---------------------------------------------------------------------------*/
 #endif /* SOC_RTC_H_ */
 /*---------------------------------------------------------------------------*/
diff --git a/cpu/cc26xx-cc13xx/lpm.c b/cpu/cc26xx-cc13xx/lpm.c
index 2f7b964f8..cc3e49023 100644
--- a/cpu/cc26xx-cc13xx/lpm.c
+++ b/cpu/cc26xx-cc13xx/lpm.c
@@ -292,7 +292,7 @@ lpm_drop()
 
     if(next_event) {
       next_event = next_event - clock_time();
-      soc_rtc_schedule_one_shot(AON_RTC_CH1, RTIMER_NOW() +
+      soc_rtc_schedule_one_shot(AON_RTC_CH1, soc_rtc_last_isr_time() +
           (next_event * (RTIMER_SECOND / CLOCK_SECOND)));
     }