2 files changed, 23 insertions, 0 deletions
diff --git a/include/hw/ptimer.h b/include/hw/ptimer.h
index 412763fffb..c443218475 100644
--- a/include/hw/ptimer.h
+++ b/include/hw/ptimer.h
@@ -166,6 +166,28 @@ void ptimer_transaction_commit(ptimer_state *s);
 void ptimer_set_period(ptimer_state *s, int64_t period);
 
 /**
+ * ptimer_set_period_from_clock - Set counter increment from a Clock
+ * @s: ptimer to configure
+ * @clk: pointer to Clock object to take period from
+ * @divisor: value to scale the clock frequency down by
+ *
+ * If the ptimer is being driven from a Clock, this is the preferred
+ * way to tell the ptimer about the period, because it avoids any
+ * possible rounding errors that might happen if the internal
+ * representation of the Clock period was converted to either a period
+ * in ns or a frequency in Hz.
+ *
+ * If the ptimer should run at the same frequency as the clock,
+ * pass 1 as the @divisor; if the ptimer should run at half the
+ * frequency, pass 2, and so on.
+ *
+ * This function will assert if it is called outside a
+ * ptimer_transaction_begin/commit block.
+ */
+void ptimer_set_period_from_clock(ptimer_state *s, const Clock *clock,
+                                  unsigned int divisor);
+
+/**
  * ptimer_set_freq - Set counter frequency in Hz
  * @s: ptimer to configure
  * @freq: counter frequency in Hz
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index 976b529dfb..68deb74ef6 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -34,6 +34,7 @@ typedef struct BlockDriverState BlockDriverState;
 typedef struct BusClass BusClass;
 typedef struct BusState BusState;
 typedef struct Chardev Chardev;
+typedef struct Clock Clock;
 typedef struct CompatProperty CompatProperty;
 typedef struct CoMutex CoMutex;
 typedef struct CPUAddressSpace CPUAddressSpace;