arch: Let CONFIG_IRQ_OFFLOAD_NESTED be overridable

This is currently selected by the arch, but some devices (in paticular
xtensa ones which have configurable interrupt setups) might not
actually be able to effect an irq_offload() from within an ISR even
though we have code for it.

Make this a default and not a select so that lower layers can override
the setting.

Signed-off-by: Andy Ross <[email protected]>

Author: andyross

arch/Kconfig

@@ -50,7 +50,6 @@ config ARM64
 	select ARCH_HAS_THREAD_LOCAL_STORAGE
 	select USE_SWITCH
 	select USE_SWITCH_SUPPORTED
-	select IRQ_OFFLOAD_NESTED if IRQ_OFFLOAD
 	select BARRIER_OPERATIONS_ARCH
 	select ARCH_HAS_DIRECTED_IPIS
 	select ARCH_HAS_DEMAND_PAGING
@@ -95,7 +94,6 @@ config X86
 	select ARCH_HAS_THREAD_LOCAL_STORAGE
 	select ARCH_HAS_DEMAND_PAGING if !X86_64
 	select ARCH_HAS_DEMAND_MAPPING if ARCH_HAS_DEMAND_PAGING
-	select IRQ_OFFLOAD_NESTED if IRQ_OFFLOAD
 	select NEED_LIBC_MEM_PARTITION if USERSPACE && TIMING_FUNCTIONS \
 					  && !BOARD_HAS_TIMING_FUNCTIONS \
 					  && !SOC_HAS_TIMING_FUNCTIONS
@@ -123,7 +121,6 @@ config RISCV
 	select ARCH_SUPPORTS_EMPTY_IRQ_SPURIOUS
 	select ARCH_HAS_CODE_DATA_RELOCATION
 	select ARCH_HAS_THREAD_LOCAL_STORAGE
-	select IRQ_OFFLOAD_NESTED if IRQ_OFFLOAD
 	select USE_SWITCH_SUPPORTED
 	select USE_SWITCH
 	select SCHED_IPI_SUPPORTED if SMP
@@ -138,7 +135,6 @@ config XTENSA
 	select ARCH_IS_SET
 	select USE_SWITCH
 	select USE_SWITCH_SUPPORTED
-	select IRQ_OFFLOAD_NESTED if IRQ_OFFLOAD
 	select ARCH_HAS_CODE_DATA_RELOCATION
 	select ARCH_HAS_TIMING_FUNCTIONS
 	select ARCH_MEM_DOMAIN_DATA if USERSPACE
@@ -581,11 +577,12 @@ config IRQ_OFFLOAD
 config IRQ_OFFLOAD_NESTED
 	bool "irq_offload() supports nested IRQs"
 	depends on IRQ_OFFLOAD
+	default y if ARM64 || X86 || RISCV || XTENSA
 	help
-	  When set by the arch layer, indicates that irq_offload() may
-	  legally be called in interrupt context to cause a
-	  synchronous nested interrupt on the current CPU.  Not all
-	  hardware is capable.
+	  When set by the platform layers, indicates that
+	  irq_offload() may legally be called in interrupt context to
+	  cause a synchronous nested interrupt on the current CPU.
+	  Not all hardware is capable.
 
 config EXCEPTION_DEBUG
 	bool "Unhandled exception debugging"