Fixing various warnings

* Missing and incorrect # Safety comments
* Unused functions and variables
* Refactoring conditional AArch64 compilation

Signed-off-by: Imre Kis <imre.kis@arm.com>
Change-Id: Ie638d1eeb2928a0c6eb0d4eb64c9d19b82f91e4d
diff --git a/src/lib.rs b/src/lib.rs
index 4c529dc..202776d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -2,7 +2,6 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
 #![allow(dead_code)]
-#![allow(non_camel_case_types)]
 #![cfg_attr(not(test), no_std)]
 
 extern crate alloc;
@@ -55,6 +54,7 @@
 /// Memory attributes
 ///
 /// MAIR_EL1 should be configured in the same way in startup.s
+#[allow(non_camel_case_types)]
 #[derive(PrimitiveEnum_u8, Clone, Copy, Debug, PartialEq, Eq, Default)]
 pub enum MemoryAttributesIndex {
     #[default]
@@ -361,6 +361,7 @@
     /// caller must ensure that the new mapping will not break any existing
     /// references. After activation the caller must ensure that there are no
     /// active references when unmapping memory.
+    #[cfg(target_arch = "aarch64")]
     pub unsafe fn activate(&self) {
         // Select translation granule
         let is_tg0 = match &self.regime {
@@ -374,7 +375,6 @@
             TranslationRegime::EL2_0(RegimeVaRange::Upper, _) => false,
         };
 
-        #[cfg(target_arch = "aarch64")]
         if is_tg0 {
             self.modify_tcr(|tcr| {
                 let tg0 = match self.granule {
@@ -400,7 +400,6 @@
         // Set translation table
         let base_table_pa = KernelSpace::kernel_to_pa(self.base_table.get_pa().0 as u64);
 
-        #[cfg(target_arch = "aarch64")]
         match &self.regime {
             TranslationRegime::EL1_0(RegimeVaRange::Lower, asid) => core::arch::asm!(
                     "msr ttbr0_el1, {0}
@@ -431,6 +430,11 @@
         }
     }
 
+    /// # Safety
+    /// Dummy functions for test builds
+    #[cfg(not(target_arch = "aarch64"))]
+    pub unsafe fn activate(&self) {}
+
     /// Modifies the TCR register of the selected regime of the instance.
     #[cfg(target_arch = "aarch64")]
     unsafe fn modify_tcr<F>(&self, f: F)
@@ -887,10 +891,10 @@
         }
     }
 
+    #[cfg(target_arch = "aarch64")]
     fn invalidate(regime: &TranslationRegime, va: Option<VirtualAddress>) {
         // SAFETY: The assembly code invalidates the translation table entry of
         // the VA or all entries of the translation regime.
-        #[cfg(target_arch = "aarch64")]
         unsafe {
             if let Some(VirtualAddress(va)) = va {
                 match regime {
@@ -949,6 +953,9 @@
             }
         }
     }
+
+    #[cfg(not(target_arch = "aarch64"))]
+    fn invalidate(_regime: &TranslationRegime, _va: Option<VirtualAddress>) {}
 }
 
 impl<const VA_BITS: usize> fmt::Debug for Xlat<VA_BITS> {