[Qemu-devel] [PATCH 2/2] hw/armv7m_nvic: Add global variable for SysTick external reference clock

[Andre Beckus <mikemail98-qemu@yahoo.com>]

Adds a new external reference clock scale variable to complement the existing
system_clock_scale variable.  Previously, the value was hardcoded to 1000
when calculating the SysTick scale.  The new variable defaults to 1000 to
maintain backward compatibility.

Signed-off-by: Andre Beckus <mikemail98-qemu@yahoo.com>
---
 hw/arm-misc.h    |    4 ++++
 hw/armv7m_nvic.c |    3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/arm-misc.h b/hw/arm-misc.h
index bdd8fec..32b19df 100644
--- a/hw/arm-misc.h
+++ b/hw/arm-misc.h
@@ -65,4 +65,8 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info);
    ticks.  */
 extern int system_clock_scale;
 
+/* Multiplication factor to convert from external reference clock ticks to
+ * qemu timer ticks. */
+extern int external_ref_clock_scale;
+
 #endif /* !ARM_MISC_H */
diff --git a/hw/armv7m_nvic.c b/hw/armv7m_nvic.c
index 10b5954..4eaa113 100644
--- a/hw/armv7m_nvic.c
+++ b/hw/armv7m_nvic.c
@@ -65,6 +65,7 @@ static const uint8_t nvic_id[] = {
 #define SYSTICK_COUNTFLAG (1 << 16)
 
 int system_clock_scale;
+int external_ref_clock_scale = 1000;
 
 /* Conversion factor from qemu timer to SysTick frequencies.  */
 static inline int64_t systick_scale(nvic_state *s)
@@ -72,7 +73,7 @@ static inline int64_t systick_scale(nvic_state *s)
     if (s->systick.control & SYSTICK_CLKSOURCE)
         return system_clock_scale;
     else
-        return 1000;
+        return external_ref_clock_scale;
 }
 
 static void systick_reload(nvic_state *s, int reset)
-- 
1.7.9.5