hw/timer/stellaris-gptm: Use Clock input instead of system_clock_scale

The stellaris-gptm timer currently uses system_clock_scale for one of
its timer modes where the timer runs at the CPU clock rate.  Make it
use a Clock input instead.

We don't try to make the timer handle changes in the clock frequency
while the downcounter is running.  This is not a change in behaviour
from the previous system_clock_scale implementation -- we will pick
up the new frequency only when the downcounter hits zero.  Handling
dynamic clock changes when the counter is running would require state
that the current gptm implementation doesn't have.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Damien Hedde <damien.hedde@greensocs.com>
Message-id: 20210812093356.1946-25-peter.maydell@linaro.org

1 files changed, 3 insertions, 0 deletions

diff --git a/include/hw/timer/stellaris-gptm.h b/include/hw/timer/stellaris-gptm.h
index b8fa43c94b..fde1fc6f0c 100644
--- a/include/hw/timer/stellaris-gptm.h
+++ b/include/hw/timer/stellaris-gptm.h
@@ -13,6 +13,7 @@
 #include "qom/object.h"
 #include "hw/sysbus.h"
 #include "hw/irq.h"
+#include "hw/clock.h"
 
 #define TYPE_STELLARIS_GPTM "stellaris-gptm"
 OBJECT_DECLARE_SIMPLE_TYPE(gptm_state, STELLARIS_GPTM)
@@ -22,6 +23,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(gptm_state, STELLARIS_GPTM)
  *  + sysbus MMIO region 0: register bank
  *  + sysbus IRQ 0: timer interrupt
  *  + unnamed GPIO output 0: trigger output for the ADC
+ *  + Clock input "clk": the 32-bit countdown timer runs at this speed
  */
 struct gptm_state {
     SysBusDevice parent_obj;
@@ -43,6 +45,7 @@ struct gptm_state {
     /* The timers have an alternate output used to trigger the ADC.  */
     qemu_irq trigger;
     qemu_irq irq;
+    Clock *clk;
 };
 
 #endif