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diff --git a/sys/powerpc/powermac/platform_powermac.c b/sys/powerpc/powermac/platform_powermac.c
--- a/sys/powerpc/powermac/platform_powermac.c
+++ b/sys/powerpc/powermac/platform_powermac.c
@@ -405,21 +405,88 @@
freeze_timebase = cb;
}
+/**
+ * @brief Implement a default platform AP/BSP SMP timebase synchronisation
+ *
+ * Some powermac platforms don't have a freeze/unfreeze method.
+ * Here just try our best to force synchronisation.
+ */
static void
-powermac_smp_timebase_sync(platform_t plat, u_long tb, int ap)
+powermac_smp_timebase_sync_fallback(platform_t plat, u_long tb, int ap)
+{
+ static volatile bool tb_ready = false;
+ static volatile int cpu_done;
+
+ if (bootverbose)
+ printf("[%d] %s: called, AP tb=0x%lx tb=0x%lx\n",
+ ap, __func__, tb, mftb());
+
+ /* Do initial timebase sync */
+ mttb(tb);
+
+ if (ap) {
+ /*
+ * APs - wait until the BSP signals its ready to sync,
+ * then wait for all CPUs to be ready.
+ */
+ critical_enter();
+ while (!tb_ready)
+ atomic_thread_fence_seq_cst();
+ atomic_add_int(&cpu_done, 1);
+ do {
+ atomic_thread_fence_seq_cst();
+ } while (cpu_done < mp_ncpus);
+ mttb(tb);
+ critical_exit();
+ } else {
+ /*
+ * BSP - signify that the timebase sync is about to start,
+ * then wait for other CPUs to be ready.
+ */
+ critical_enter();
+ /* Ensure cpu_done is zeroed so we can resync at runtime */
+ atomic_store_int(&cpu_done, 0);
+ tb_ready = true;
+ atomic_add_int(&cpu_done, 1);
+ do {
+ atomic_thread_fence_seq_cst();
+ } while (cpu_done < mp_ncpus);
+ mttb(tb);
+ /* Reset tb_ready so we can resync at runtime */
+ tb_ready = false;
+ critical_exit();
+ }
+ if (bootverbose)
+ printf("[%d] %s: finished; AP tb=0x%lx called tb=0x%lx\n",
+ ap, __func__, tb, mftb());
+}
+
+/**
+ * @brief Implement freeze/unfreeze AP/BSP SMP timebase synchronisation
+ *
+ * This implements SMP timebase synchronisation for hardware that
+ * implements freezing a shared timebase clock source.
+ *
+ * The BSP will freeze the timebase and signal the APs to program their
+ * local timebase with the shared timebase value. The BSP will then
+ * unfreeze the timebase clock, allowing all CPUs to march forward
+ * from the same base timebase value.
+ */
+static void
+powermac_smp_timebase_sync_freeze(platform_t plat, u_long tb, int ap)
{
- static volatile bool tb_ready;
+ static volatile bool tb_ready = false;
static volatile int cpu_done;
+ if (bootverbose)
+ printf("[%d] %s: called, AP tb=0x%lx tb=0x%lx\n",
+ ap, __func__, tb, mftb());
+
/*
- * XXX Temporary fallback for platforms we don't know how to freeze.
- *
* This needs to be replaced with a cpu-to-cpu software sync
* protocol, because this is not a consistent way to sync timebase.
*/
mttb(tb);
- if (freeze_timebase == dummy_timebase)
- return;
if (ap) {
/* APs. Hold off until we get a stable timebase. */
@@ -428,25 +495,39 @@
atomic_thread_fence_seq_cst();
mttb(tb);
atomic_add_int(&cpu_done, 1);
- while (cpu_done < mp_ncpus)
+ do {
atomic_thread_fence_seq_cst();
+ } while (cpu_done < mp_ncpus);
critical_exit();
} else {
/* BSP */
critical_enter();
/* Ensure cpu_done is zeroed so we can resync at runtime */
- atomic_set_int(&cpu_done, 0);
+ atomic_store_int(&cpu_done, 0);
freeze_timebase(powermac_tb_dev, true);
tb_ready = true;
mttb(tb);
atomic_add_int(&cpu_done, 1);
- while (cpu_done < mp_ncpus)
+ do {
atomic_thread_fence_seq_cst();
+ } while (cpu_done < mp_ncpus);
freeze_timebase(powermac_tb_dev, false);
/* Reset tb_ready so we can resync at runtime */
tb_ready = false;
critical_exit();
}
+ if (bootverbose)
+ printf("[%d] %s: finished; AP tb=0x%lx called tb=0x%lx\n",
+ ap, __func__, tb, mftb());
+}
+
+static void
+powermac_smp_timebase_sync(platform_t plat, u_long tb, int ap)
+{
+ if (freeze_timebase == dummy_timebase)
+ powermac_smp_timebase_sync_fallback(plat, tb, ap);
+ else
+ powermac_smp_timebase_sync_freeze(plat, tb, ap);
}
/* Fallback freeze. In case no real handler is found in the device tree. */

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