[PATCH 22/25] hw/arm/armsse: Use Clock to set system_clock_scale

[Peter Maydell <peter.maydell@linaro.org>]

Use the MAINCLK Clock input to set the system_clock_scale variable
rather than using the mainclk_frq property.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
At some point we should make the SysTick take a Clock itself so
that we can get rid of the system_clock_scale global entirely.
(In fact we want two Clocks: one that is the CPU clock and one
for the 'external reference clock' whose period is currently
hardcoded at 1000ns in systick_scale()...)
---
 hw/arm/armsse.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/hw/arm/armsse.c b/hw/arm/armsse.c
index 4349ce9bfdb..1da0c1be4c7 100644
--- a/hw/arm/armsse.c
+++ b/hw/arm/armsse.c
@@ -232,6 +232,16 @@ static void armsse_forward_sec_resp_cfg(ARMSSE *s)
     qdev_connect_gpio_out(dev_splitter, 2, s->sec_resp_cfg_in);
 }
 
+static void armsse_mainclk_update(void *opaque)
+{
+    ARMSSE *s = ARM_SSE(opaque);
+    /*
+     * Set system_clock_scale from our Clock input; this is what
+     * controls the tick rate of the CPU SysTick timer.
+     */
+    system_clock_scale = clock_ticks_to_ns(s->mainclk, 1);
+}
+
 static void armsse_init(Object *obj)
 {
     ARMSSE *s = ARM_SSE(obj);
@@ -451,9 +461,11 @@ static void armsse_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    if (!s->mainclk_frq) {
-        error_setg(errp, "MAINCLK_FRQ property was not set");
-        return;
+    if (!clock_has_source(s->mainclk)) {
+        error_setg(errp, "MAINCLK clock was not connected");
+    }
+    if (!clock_has_source(s->s32kclk)) {
+        error_setg(errp, "S32KCLK clock was not connected");
     }
 
     assert(info->num_cpus <= SSE_MAX_CPUS);
@@ -1115,7 +1127,8 @@ static void armsse_realize(DeviceState *dev, Error **errp)
      */
     sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->container);
 
-    system_clock_scale = NANOSECONDS_PER_SECOND / s->mainclk_frq;
+    /* Set initial system_clock_scale from MAINCLK */
+    armsse_mainclk_update(s);
 }
 
 static void armsse_idau_check(IDAUInterface *ii, uint32_t address,
-- 
2.20.1