[Qemu-arm] [PATCH v11 7/7] arm_mptimer: Convert to use ptimer

[Dmitry Osipenko]

Current ARM MPTimer implementation uses QEMUTimer for the actual timer,
this implementation isn't complete and mostly tries to duplicate of what
generic ptimer is already doing fine.

Conversion to ptimer brings the following benefits and fixes:
        - Simple timer pausing implementation
        - Fixes counter value preservation after stopping the timer
        - Correctly handles prescaler != 0 cases
        - Code simplification and reduction

Bump VMSD to version 3, since VMState is changed and is not compatible
with the previous implementation.

Signed-off-by: Dmitry Osipenko <address@hidden>
---
 hw/timer/arm_mptimer.c         | 131 +++++++++++++++++++++--------------------
 include/hw/timer/arm_mptimer.h |   5 +-
 2 files changed, 67 insertions(+), 69 deletions(-)

diff --git a/hw/timer/arm_mptimer.c b/hw/timer/arm_mptimer.c
index 3e59c2a..a5f46df 100644
--- a/hw/timer/arm_mptimer.c
+++ b/hw/timer/arm_mptimer.c
@@ -19,8 +19,9 @@
  * with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "hw/ptimer.h"
 #include "hw/timer/arm_mptimer.h"
-#include "qemu/timer.h"
+#include "qemu/main-loop.h"
 #include "qom/cpu.h"
 
 /* This device implements the per-cpu private timer and watchdog block
@@ -42,33 +43,34 @@ static inline void timerblock_update_irq(TimerBlock *tb)
 }
 
 /* Return conversion factor from mpcore timer ticks to qemu timer ticks.  */
-static inline uint32_t timerblock_scale(TimerBlock *tb)
+static inline uint32_t timerblock_scale(uint32_t control)
 {
-    return (((tb->control >> 8) & 0xff) + 1) * 10;
+    return (((control >> 8) & 0xff) + 1) * 10;
 }
 
-static void timerblock_reload(TimerBlock *tb, int restart)
+static inline void timerblock_set_count(struct ptimer_state *timer,
+                                        uint32_t control, uint64_t *count)
 {
-    if (tb->count == 0) {
-        return;
+    /* PTimer would immediately trigger interrupt for periodic timer
+     * when counter set to 0, MPtimer under certain condition only.  */
+    if ((control & 3) == 3 && (*count == 0) && (control & 0xff00) == 0) {
+        *count = ptimer_get_limit(timer);
     }
-    if (restart) {
-        tb->tick = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
+    ptimer_set_count(timer, *count);
+}
+
+static inline void timerblock_run(struct ptimer_state *timer, uint32_t control,
+                                  bool cond)
+{
+    if (cond) {
+        ptimer_run(timer, !(control & 2));
     }
-    tb->tick += (int64_t)tb->count * timerblock_scale(tb);
-    timer_mod(tb->timer, tb->tick);
 }
 
 static void timerblock_tick(void *opaque)
 {
     TimerBlock *tb = (TimerBlock *)opaque;
     tb->status = 1;
-    if (tb->control & 2) {
-        tb->count = tb->load;
-        timerblock_reload(tb, 0);
-    } else {
-        tb->count = 0;
-    }
     timerblock_update_irq(tb);
 }
 
@@ -76,21 +78,11 @@ static uint64_t timerblock_read(void *opaque, hwaddr addr,
                                 unsigned size)
 {
     TimerBlock *tb = (TimerBlock *)opaque;
-    int64_t val;
     switch (addr) {
     case 0: /* Load */
-        return tb->load;
+        return ptimer_get_limit(tb->timer);
     case 4: /* Counter.  */
-        if (((tb->control & 1) == 0) || (tb->count == 0)) {
-            return 0;
-        }
-        /* Slow and ugly, but hopefully won't happen too often.  */
-        val = tb->tick - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
-        val /= timerblock_scale(tb);
-        if (val < 0) {
-            val = 0;
-        }
-        return val;
+        return ptimer_get_count(tb->timer);
     case 8: /* Control.  */
         return tb->control;
     case 12: /* Interrupt status.  */
@@ -104,39 +96,51 @@ static void timerblock_write(void *opaque, hwaddr addr,
                              uint64_t value, unsigned size)
 {
     TimerBlock *tb = (TimerBlock *)opaque;
-    int64_t old;
+    uint32_t control = tb->control;
     switch (addr) {
     case 0: /* Load */
-        tb->load = value;
-        /* Fall through.  */
-    case 4: /* Counter.  */
-        if ((tb->control & 1) && tb->count) {
-            /* Cancel the previous timer.  */
-            timer_del(tb->timer);
+        /* Setting load to 0 stops the timer if prescaler == 0.  */
+        if ((control & 1) && (value == 0) && (control & 0xff00) == 0) {
+            ptimer_stop(tb->timer);
+            control &= ~1;
         }
-        tb->count = value;
-        if (tb->control & 1) {
-            timerblock_reload(tb, 1);
+        ptimer_set_limit(tb->timer, value, 1);
+        timerblock_run(tb->timer, control, (control & 1));
+        break;
+    case 4: /* Counter.  */
+        /* Setting counter to 0 stops the one-shot timer if prescaler == 0
+         * and periodic if load = 0.  */
+        if ((control & 1) && (value == 0) && (control & 0xff00) == 0) {
+            if (!(control & 2) || ptimer_get_limit(tb->timer) == 0) {
+                ptimer_stop(tb->timer);
+                control &= ~1;
+            }
         }
+        timerblock_set_count(tb->timer, control, &value);
+        timerblock_run(tb->timer, control, (value != 0) && (control & 1));
         break;
     case 8: /* Control.  */
-        old = tb->control;
-        tb->control = value;
-        if (value & 1) {
-            if ((old & 1) && (tb->count != 0)) {
-                /* Do nothing if timer is ticking right now.  */
-                break;
+        if ((value & 1) && (control & 3) != (value & 3)) {
+            uint64_t count = (value & 0xff00) ? 1 : 
ptimer_get_count(tb->timer);
+            if ((count == 0) && (value & 2)) {
+                timerblock_set_count(tb->timer, value, &count);
             }
-            if (tb->control & 2) {
-                tb->count = tb->load;
-            }
-            timerblock_reload(tb, 1);
-        } else if (old & 1) {
-            /* Shutdown the timer.  */
-            timer_del(tb->timer);
+            timerblock_run(tb->timer, value, (count != 0));
+        } else if ((control & 1) && !(value & 1)) {
+            ptimer_stop(tb->timer);
+        }
+        if ((control & 0xff00) != (value & 0xff00)) {
+            ptimer_set_period(tb->timer, timerblock_scale(value));
         }
+        tb->control = value;
         break;
     case 12: /* Interrupt status.  */
+        /* Simulate continuous IRQ gen.  */
+        if ((control & 3) == 3 && (control & 0xff00) != 0) {
+            if (ptimer_get_limit(tb->timer) == 0) {
+                break;
+            }
+        }
         tb->status &= ~value;
         timerblock_update_irq(tb);
         break;
@@ -184,13 +188,12 @@ static const MemoryRegionOps timerblock_ops = {
 
 static void timerblock_reset(TimerBlock *tb)
 {
-    tb->count = 0;
-    tb->load = 0;
     tb->control = 0;
     tb->status = 0;
-    tb->tick = 0;
     if (tb->timer) {
-        timer_del(tb->timer);
+        ptimer_stop(tb->timer);
+        ptimer_set_limit(tb->timer, 0, 1);
+        ptimer_set_period(tb->timer, timerblock_scale(0));
     }
 }
 
@@ -235,7 +238,8 @@ static void arm_mptimer_realize(DeviceState *dev, Error 
**errp)
      */
     for (i = 0; i < s->num_cpu; i++) {
         TimerBlock *tb = &s->timerblock[i];
-        tb->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, timerblock_tick, tb);
+        QEMUBH *bh = qemu_bh_new(timerblock_tick, tb);
+        tb->timer = ptimer_init(bh);
         sysbus_init_irq(sbd, &tb->irq);
         memory_region_init_io(&tb->iomem, OBJECT(s), &timerblock_ops, tb,
                               "arm_mptimer_timerblock", 0x20);
@@ -245,26 +249,23 @@ static void arm_mptimer_realize(DeviceState *dev, Error 
**errp)
 
 static const VMStateDescription vmstate_timerblock = {
     .name = "arm_mptimer_timerblock",
-    .version_id = 2,
-    .minimum_version_id = 2,
+    .version_id = 3,
+    .minimum_version_id = 3,
     .fields = (VMStateField[]) {
-        VMSTATE_UINT32(count, TimerBlock),
-        VMSTATE_UINT32(load, TimerBlock),
         VMSTATE_UINT32(control, TimerBlock),
         VMSTATE_UINT32(status, TimerBlock),
-        VMSTATE_INT64(tick, TimerBlock),
-        VMSTATE_TIMER_PTR(timer, TimerBlock),
+        VMSTATE_PTIMER(timer, TimerBlock),
         VMSTATE_END_OF_LIST()
     }
 };
 
 static const VMStateDescription vmstate_arm_mptimer = {
     .name = "arm_mptimer",
-    .version_id = 2,
-    .minimum_version_id = 2,
+    .version_id = 3,
+    .minimum_version_id = 3,
     .fields = (VMStateField[]) {
         VMSTATE_STRUCT_VARRAY_UINT32(timerblock, ARMMPTimerState, num_cpu,
-                                     2, vmstate_timerblock, TimerBlock),
+                                     3, vmstate_timerblock, TimerBlock),
         VMSTATE_END_OF_LIST()
     }
 };
diff --git a/include/hw/timer/arm_mptimer.h b/include/hw/timer/arm_mptimer.h
index b34cba0..c46d8d2 100644
--- a/include/hw/timer/arm_mptimer.h
+++ b/include/hw/timer/arm_mptimer.h
@@ -27,12 +27,9 @@
 
 /* State of a single timer or watchdog block */
 typedef struct {
-    uint32_t count;
-    uint32_t load;
     uint32_t control;
     uint32_t status;
-    int64_t tick;
-    QEMUTimer *timer;
+    struct ptimer_state *timer;
     qemu_irq irq;
     MemoryRegion iomem;
 } TimerBlock;
-- 
2.7.0