add support to not compile with dummy FIQ handler

cfg: add dummy FIQ handler cfg
abort: gate dummy FIQ handler using cfg

experiments/Cargo.toml

@@ -18,5 +18,5 @@ embedded-hal = "0.2"
 libregister = { path = "../libregister" }
 libcortex_a9 = { path = "../libcortex_a9" }
 libboard_zynq = { path = "../libboard_zynq" }
-libsupport_zynq = { path = "../libsupport_zynq", default-features = false, features = ["panic_handler"]}
+libsupport_zynq = { path = "../libsupport_zynq", default-features = false, features = ["panic_handler", "dummy_fiq_handler"]}
 libasync = { path = "../libasync" }

libcortex_a9/src/asm.rs

@@ -34,6 +34,12 @@ pub fn isb() {
     unsafe { llvm_asm!("isb" :::: "volatile") }
 }
 
+/// Enable FIQ
+#[inline]
+pub unsafe fn enable_fiq() {
+    llvm_asm!("cpsie f":::: "volatile");
+}
+
 /// Enable IRQ
 #[inline]
 pub unsafe fn enable_irq() {

libsupport_zynq/Cargo.toml

@@ -12,9 +12,10 @@ target_redpitaya = ["libboard_zynq/target_redpitaya"]
 target_kasli_soc = ["libboard_zynq/target_kasli_soc"]
 panic_handler = []
 dummy_irq_handler = []
+dummy_fiq_handler = []
 alloc_core = []
 
-default = ["panic_handler", "dummy_irq_handler"]
+default = ["panic_handler", "dummy_irq_handler", "dummy_fiq_handler"]
 
 [dependencies]
 r0 = "1"

libsupport_zynq/src/abort.rs

@@ -42,6 +42,7 @@ interrupt_handler!(IRQ, irq, __irq_stack0_start, __irq_stack1_start, {
     loop {}
 });
 
+#[cfg(feature = "dummy_fiq_handler")]
 interrupt_handler!(FIQ, fiq, __irq_stack0_start, __irq_stack1_start, {
     stdio::drop_uart();
     println!("FIQ");

libsupport_zynq/src/boot.rs

@@ -54,6 +54,7 @@ unsafe extern "C" fn boot_core0() -> ! {
         asm::dmb();
         asm::dsb();
 
+        asm::enable_fiq();
         asm::enable_irq();
         main_core0();
         panic!("return from main");
@@ -75,6 +76,7 @@ unsafe extern "C" fn boot_core1() -> ! {
         asm::dmb();
         asm::dsb();
 
+        asm::enable_fiq();
         asm::enable_irq();
         main_core1();
         panic!("return from main_core1");