From 6d05dd07f59ef21dc81a299e865cdee1fc1d3f8e Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin@koconnor.net>
Date: Mon, 27 Mar 2017 16:38:01 -0400
Subject: [PATCH] sched: Move timer dispatch loop to board code

Rename sched_timer_kick() to sched_timer_dispatch() and move its loop
into its callers in the board code.  This eliminates the need to
export timer_try_set_next() from the board code.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
---
 docs/Code_Overview.md |  6 ++---
 src/avr/timer.c       | 20 ++++++++++-----
 src/generic/misc.h    |  1 -
 src/generic/timer.c   | 16 +++++++++++-
 src/sam3x8e/timer.c   |  5 +++-
 src/sched.c           | 57 ++++++++++++++++++++-----------------------
 src/sched.h           |  2 +-
 src/simulator/main.c  |  6 -----
 8 files changed, 63 insertions(+), 50 deletions(-)

diff --git a/docs/Code_Overview.md b/docs/Code_Overview.md
index ee640457..8b1ca06c 100644
--- a/docs/Code_Overview.md
+++ b/docs/Code_Overview.md
@@ -58,9 +58,9 @@ Timer functions are scheduled by calling sched_add_timer() (located in
 **src/sched.c**). The scheduler code will arrange for the given
 function to be called at the requested clock time. Timer interrupts
 are initially handled in an architecture specific interrupt handler
-(eg, **src/avr/timer.c**), but this just calls sched_timer_kick()
-located in **src/sched.c**. The timer interrupt leads to execution of
-schedule timer functions.  Timer functions always run with interrupts
+(eg, **src/avr/timer.c**) which calls sched_timer_dispatch() located
+in **src/sched.c**. The timer interrupt leads to execution of schedule
+timer functions. Timer functions always run with interrupts
 disabled. The timer functions should always complete within a few
 micro-seconds. At completion of the timer event, the function may
 choose to reschedule itself.
diff --git a/src/avr/timer.c b/src/avr/timer.c
index e9ec8dd0..f8686998 100644
--- a/src/avr/timer.c
+++ b/src/avr/timer.c
@@ -70,11 +70,6 @@ timer_repeat_set(uint16_t next)
     TIFR1 = 1<<OCF1B;
 }
 
-ISR(TIMER1_COMPA_vect)
-{
-    sched_timer_kick();
-}
-
 static void
 timer_init(void)
 {
@@ -143,7 +138,7 @@ timer_periodic(void)
 // Set the next timer wake time (in absolute clock ticks) or return 1
 // if the next timer is too close to schedule.  Caller must disable
 // irqs.
-uint8_t
+static uint8_t
 timer_try_set_next(unsigned int target)
 {
     uint16_t next = target;
@@ -189,6 +184,19 @@ fail:
     shutdown("Rescheduled timer in the past");
 }
 
+// Harware OCR1A interrupt handler
+ISR(TIMER1_COMPA_vect)
+{
+    for (;;) {
+        uint16_t next_waketime = sched_timer_dispatch();
+
+        // Schedule next timer event (or run next timer if it's ready)
+        uint8_t res = timer_try_set_next(next_waketime);
+        if (res)
+            break;
+    }
+}
+
 // Periodic background task that temporarily boosts priority of
 // timers.  This helps prioritize timers when tasks are idling.
 static void
diff --git a/src/generic/misc.h b/src/generic/misc.h
index bc3223e7..e8a13c00 100644
--- a/src/generic/misc.h
+++ b/src/generic/misc.h
@@ -13,7 +13,6 @@ uint32_t timer_from_us(uint32_t us);
 uint8_t timer_is_before(uint32_t time1, uint32_t time2);
 uint32_t timer_read_time(void);
 void timer_periodic(void);
-uint8_t timer_try_set_next(unsigned int next);
 
 size_t alloc_maxsize(size_t reqsize);
 
diff --git a/src/generic/timer.c b/src/generic/timer.c
index 5185ed54..fba56051 100644
--- a/src/generic/timer.c
+++ b/src/generic/timer.c
@@ -49,7 +49,7 @@ static uint32_t timer_repeat_until;
 // Set the next timer wake time (in absolute clock ticks) or return 1
 // if the next timer is too close to schedule.  Caller must disable
 // irqs.
-uint8_t
+static int
 timer_try_set_next(unsigned int next)
 {
     uint32_t now = timer_read_time();
@@ -84,6 +84,20 @@ fail:
     shutdown("Rescheduled timer in the past");
 }
 
+// Invoke timers - called from board irq code.
+void
+timer_dispatch_many(void)
+{
+    for (;;) {
+        uint32_t next_waketime = sched_timer_dispatch();
+
+        // Schedule next timer event (or run next timer if it's ready)
+        int res = timer_try_set_next(next_waketime);
+        if (res)
+            break;
+    }
+}
+
 // Periodic background task that temporarily boosts priority of
 // timers.  This helps prioritize timers when tasks are idling.
 static void
diff --git a/src/sam3x8e/timer.c b/src/sam3x8e/timer.c
index e450d21e..dcc8dbd2 100644
--- a/src/sam3x8e/timer.c
+++ b/src/sam3x8e/timer.c
@@ -10,6 +10,9 @@
 #include "sam3x8e.h" // TC0
 #include "sched.h" // sched_timer_kick
 
+// From generic/timer.c
+extern void timer_dispatch_many(void);
+
 // IRQ handler
 void __visible
 TC0_Handler(void)
@@ -17,7 +20,7 @@ TC0_Handler(void)
     irq_disable();
     uint32_t status = TC0->TC_CHANNEL[0].TC_SR; // read to clear irq pending
     if (likely(status & TC_SR_CPAS))
-        sched_timer_kick();
+        timer_dispatch_many();
     irq_enable();
 }
 
diff --git a/src/sched.c b/src/sched.c
index 2b96465f..8617108a 100644
--- a/src/sched.c
+++ b/src/sched.c
@@ -135,39 +135,34 @@ sched_del_timer(struct timer *del)
     irq_restore(flag);
 }
 
-// Invoke timers - called from board timer irq code.
-void
-sched_timer_kick(void)
+// Invoke the next timer - called from board hardware irq code.
+unsigned int
+sched_timer_dispatch(void)
 {
-    for (;;) {
-        // Invoke timer callback
-        struct timer *t = timer_list;
-        uint_fast8_t res;
-        uint32_t updated_waketime;
-        if (CONFIG_INLINE_STEPPER_HACK && likely(!t->func)) {
-            res = stepper_event(t);
-            updated_waketime = t->waketime;
-        } else {
-            res = t->func(t);
-            updated_waketime = t->waketime;
-        }
-
-        // Update timer_list (rescheduling current timer if necessary)
-        unsigned int next_waketime = updated_waketime;
-        if (unlikely(res == SF_DONE)) {
-            next_waketime = t->next->waketime;
-            timer_list = t->next;
-        } else if (!timer_is_before(updated_waketime, t->next->waketime)) {
-            next_waketime = t->next->waketime;
-            timer_list = t->next;
-            insert_timer(t, updated_waketime);
-        }
-
-        // Schedule next timer event (or run next timer if it's ready)
-        res = timer_try_set_next(next_waketime);
-        if (res)
-            break;
+    // Invoke timer callback
+    struct timer *t = timer_list;
+    uint_fast8_t res;
+    uint32_t updated_waketime;
+    if (CONFIG_INLINE_STEPPER_HACK && likely(!t->func)) {
+        res = stepper_event(t);
+        updated_waketime = t->waketime;
+    } else {
+        res = t->func(t);
+        updated_waketime = t->waketime;
     }
+
+    // Update timer_list (rescheduling current timer if necessary)
+    unsigned int next_waketime = updated_waketime;
+    if (unlikely(res == SF_DONE)) {
+        next_waketime = t->next->waketime;
+        timer_list = t->next;
+    } else if (!timer_is_before(updated_waketime, t->next->waketime)) {
+        next_waketime = t->next->waketime;
+        timer_list = t->next;
+        insert_timer(t, updated_waketime);
+    }
+
+    return next_waketime;
 }
 
 // Shutdown all user timers on an emergency stop.
diff --git a/src/sched.h b/src/sched.h
index 7a98257a..d2d3471e 100644
--- a/src/sched.h
+++ b/src/sched.h
@@ -25,7 +25,7 @@ enum { SF_DONE=0, SF_RESCHEDULE=1 };
 uint8_t sched_check_periodic(uint16_t time, uint16_t *pnext);
 void sched_add_timer(struct timer*);
 void sched_del_timer(struct timer *del);
-void sched_timer_kick(void);
+unsigned int sched_timer_dispatch(void);
 uint8_t sched_is_shutdown(void);
 uint16_t sched_shutdown_reason(void);
 void sched_clear_shutdown(void);
diff --git a/src/simulator/main.c b/src/simulator/main.c
index eb3025ca..42fb7a25 100644
--- a/src/simulator/main.c
+++ b/src/simulator/main.c
@@ -75,12 +75,6 @@ timer_read_time(void)
     return 0; // XXX
 }
 
-uint8_t
-timer_try_set_next(unsigned int next)
-{
-    return 1;
-}
-
 
 /****************************************************************
  * Turn stdin/stdout into serial console