Re: [PATCH 5/8] hw/timer/altera_timer.c: Switch to transaction-based ptimer API

[Philippe Mathieu-Daudé]

On 10/17/19 3:29 PM, Peter Maydell wrote:

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

Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
---
  hw/timer/altera_timer.c | 13 +++++++++----
  1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/hw/timer/altera_timer.c b/hw/timer/altera_timer.c
index ee32e0ec1ff..79fc381252d 100644
--- a/hw/timer/altera_timer.c
+++ b/hw/timer/altera_timer.c
@@ -19,7 +19,6 @@
   */

#include "qemu/osdep.h"

-#include "qemu/main-loop.h"
  #include "qemu/module.h"
  #include "qapi/error.h"

@@ -53,7 +52,6 @@ typedef struct AlteraTimer {

      MemoryRegion  mmio;
      qemu_irq      irq;
      uint32_t      freq_hz;
-    QEMUBH       *bh;
      ptimer_state *ptimer;
      uint32_t      regs[R_MAX];
  } AlteraTimer;
@@ -105,6 +103,7 @@ static void timer_write(void *opaque, hwaddr addr,
          break;

case R_CONTROL:

+        ptimer_transaction_begin(t->ptimer);
          t->regs[R_CONTROL] = value & (CONTROL_ITO | CONTROL_CONT);
          if ((value & CONTROL_START) &&
              !(t->regs[R_STATUS] & STATUS_RUN)) {
@@ -115,10 +114,12 @@ static void timer_write(void *opaque, hwaddr addr,
              ptimer_stop(t->ptimer);
              t->regs[R_STATUS] &= ~STATUS_RUN;
          }
+        ptimer_transaction_commit(t->ptimer);
          break;

case R_PERIODL:

      case R_PERIODH:
+        ptimer_transaction_begin(t->ptimer);
          t->regs[addr] = value & 0xFFFF;
          if (t->regs[R_STATUS] & STATUS_RUN) {
              ptimer_stop(t->ptimer);
@@ -126,6 +127,7 @@ static void timer_write(void *opaque, hwaddr addr,
          }
          tvalue = (t->regs[R_PERIODH] << 16) | t->regs[R_PERIODL];
          ptimer_set_limit(t->ptimer, tvalue + 1, 1);
+        ptimer_transaction_commit(t->ptimer);
          break;

case R_SNAPL:

@@ -183,9 +185,10 @@ static void altera_timer_realize(DeviceState *dev, Error 
**errp)
          return;
      }

- t->bh = qemu_bh_new(timer_hit, t);

-    t->ptimer = ptimer_init_with_bh(t->bh, PTIMER_POLICY_DEFAULT);
+    t->ptimer = ptimer_init(timer_hit, t, PTIMER_POLICY_DEFAULT);
+    ptimer_transaction_begin(t->ptimer);
      ptimer_set_freq(t->ptimer, t->freq_hz);
+    ptimer_transaction_commit(t->ptimer);

This looks odd because timers are not running at this point (REALIZE),
but if we don't protect it, ptimer_set_freq() will trigger the assertion.

Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>

memory_region_init_io(&t->mmio, OBJECT(t), &timer_ops, t,

                            TYPE_ALTERA_TIMER, R_MAX * sizeof(uint32_t));
@@ -204,8 +207,10 @@ static void altera_timer_reset(DeviceState *dev)
  {
      AlteraTimer *t = ALTERA_TIMER(dev);

+ ptimer_transaction_begin(t->ptimer);

      ptimer_stop(t->ptimer);
      ptimer_set_limit(t->ptimer, 0xffffffff, 1);
+    ptimer_transaction_commit(t->ptimer);
      memset(t->regs, 0, sizeof(t->regs));
  }