A SoC will not have a direct access to the NVIC embedded in its ARM
core. By aliasing the "num-prio-bits" property similarly to what is
done for the "num-irq" one, a SoC can easily configure it on its
armv7m instance.

Signed-off-by: Samuel Tardieu <sam@rfc1149.net>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/arm/armv7m.c         | 2 ++
 include/hw/arm/armv7m.h | 1 +
 2 files changed, 3 insertions(+)

diff --git a/hw/arm/armv7m.c b/hw/arm/armv7m.c
index e39b61bc1a..1f21827773 100644
--- a/hw/arm/armv7m.c
+++ b/hw/arm/armv7m.c
@@ -256,6 +256,8 @@ static void armv7m_instance_init(Object *obj)
     object_initialize_child(obj, "nvic", &s->nvic, TYPE_NVIC);
     object_property_add_alias(obj, "num-irq",
                               OBJECT(&s->nvic), "num-irq");
+    object_property_add_alias(obj, "num-prio-bits",
+                              OBJECT(&s->nvic), "num-prio-bits");
 
     object_initialize_child(obj, "systick-reg-ns", &s->systick[M_REG_NS],
                             TYPE_SYSTICK);
diff --git a/include/hw/arm/armv7m.h b/include/hw/arm/armv7m.h
index e2cebbd15c..5c057ab2ec 100644
--- a/include/hw/arm/armv7m.h
+++ b/include/hw/arm/armv7m.h
@@ -43,6 +43,7 @@ OBJECT_DECLARE_SIMPLE_TYPE(ARMv7MState, ARMV7M)
  *   a qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET).
  * + Property "cpu-type": CPU type to instantiate
  * + Property "num-irq": number of external IRQ lines
+ * + Property "num-prio-bits": number of priority bits in the NVIC
  * + Property "memory": MemoryRegion defining the physical address space
  *   that CPU accesses see. (The NVIC, bitbanding and other CPU-internal
  *   devices will be automatically layered on top of this view.)
-- 
2.42.0

On 6/1/24 19:15, Samuel Tardieu wrote:
> A SoC will not have a direct access to the NVIC embedded in its ARM
> core. By aliasing the "num-prio-bits" property similarly to what is
> done for the "num-irq" one, a SoC can easily configure it on its
> armv7m instance.
> 
> Signed-off-by: Samuel Tardieu <sam@rfc1149.net>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   hw/arm/armv7m.c         | 2 ++
>   include/hw/arm/armv7m.h | 1 +
>   2 files changed, 3 insertions(+)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>