[RFC 4/4] hw/timer/arm_timer.c: Switch to transaction-based ptimer API

[Peter Maydell <peter.maydell@linaro.org>]

Switch the arm_timer.c code away from bottom-half based ptimers
to the new transaction-based ptimer API. This just requires
adding begin/commit calls around the various arms of
arm_timer_write() that modify the ptimer state, and using the
new ptimer_init() function to create the timer.

Fixes: https://bugs.launchpad.net/qemu/+bug/1777777
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/timer/arm_timer.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/hw/timer/arm_timer.c b/hw/timer/arm_timer.c
index 848fbcb0e25..255def3deec 100644
--- a/hw/timer/arm_timer.c
+++ b/hw/timer/arm_timer.c
@@ -14,7 +14,6 @@
 #include "hw/irq.h"
 #include "hw/ptimer.h"
 #include "hw/qdev-properties.h"
-#include "qemu/main-loop.h"
 #include "qemu/module.h"
 #include "qemu/log.h"
 #include "trace.h"
@@ -79,7 +78,10 @@ static uint32_t arm_timer_read(void *opaque, hwaddr offset)
     }
 }
 
-/* Reset the timer limit after settings have changed.  */
+/*
+ * Reset the timer limit after settings have changed.
+ * May only be called from inside a ptimer transaction block.
+ */
 static void arm_timer_recalibrate(arm_timer_state *s, int reload)
 {
     uint32_t limit;
@@ -106,13 +108,16 @@ static void arm_timer_write(void *opaque, hwaddr offset,
     switch (offset >> 2) {
     case 0: /* TimerLoad */
         s->limit = value;
+        ptimer_transaction_begin(s->timer);
         arm_timer_recalibrate(s, 1);
+        ptimer_transaction_commit(s->timer);
         break;
     case 1: /* TimerValue */
         /* ??? Linux seems to want to write to this readonly register.
            Ignore it.  */
         break;
     case 2: /* TimerControl */
+        ptimer_transaction_begin(s->timer);
         if (s->control & TIMER_CTRL_ENABLE) {
             /* Pause the timer if it is running.  This may cause some
                inaccuracy dure to rounding, but avoids a whole lot of other
@@ -132,13 +137,16 @@ static void arm_timer_write(void *opaque, hwaddr offset,
             /* Restart the timer if still enabled.  */
             ptimer_run(s->timer, (s->control & TIMER_CTRL_ONESHOT) != 0);
         }
+        ptimer_transaction_commit(s->timer);
         break;
     case 3: /* TimerIntClr */
         s->int_level = 0;
         break;
     case 6: /* TimerBGLoad */
         s->limit = value;
+        ptimer_transaction_begin(s->timer);
         arm_timer_recalibrate(s, 0);
+        ptimer_transaction_commit(s->timer);
         break;
     default:
         qemu_log_mask(LOG_GUEST_ERROR,
@@ -170,14 +178,12 @@ static const VMStateDescription vmstate_arm_timer = {
 static arm_timer_state *arm_timer_init(uint32_t freq)
 {
     arm_timer_state *s;
-    QEMUBH *bh;
 
     s = (arm_timer_state *)g_malloc0(sizeof(arm_timer_state));
     s->freq = freq;
     s->control = TIMER_CTRL_IE;
 
-    bh = qemu_bh_new(arm_timer_tick, s);
-    s->timer = ptimer_init_with_bh(bh, PTIMER_POLICY_DEFAULT);
+    s->timer = ptimer_init(arm_timer_tick, s, PTIMER_POLICY_DEFAULT);
     vmstate_register(NULL, -1, &vmstate_arm_timer, s);
     return s;
 }
-- 
2.20.1