add some prelim coreuser test routines

these currently only make sense in a simulation environment,
but they allow us to work the significant configuration test
cases for practical execution to make sure we haven't missed
something in the coreuser spec.

loader/src/main.rs

@@ -85,6 +85,11 @@ pub enum IniType {
 pub unsafe extern "C" fn rust_entry(signed_buffer: *const usize, signature: u32) -> ! {
     #[cfg(all(feature = "cramium-soc", not(feature = "verilator-only")))]
     let perclk_freq = crate::platform::early_init(); // sets up PLLs so we're not running at 16MHz...
+    // need to make this "official" for NTO, the feature flag combo below works around some simulation config
+    // conflicts.
+    #[cfg(all(feature = "verilator-only", not(feature = "cramium-mpw")))]
+    platform::coreuser_config();
+
     #[cfg(not(all(feature = "cramium-soc", not(feature = "verilator-only"))))]
     let perclk_freq = 0;
 

loader/src/platform/cramium/cramium.rs

@@ -1975,3 +1975,35 @@ pub unsafe fn init_clock_asic_c(freq_hz: u32, duty_sram: u32) -> u32 {
 
     100_000_000 // bodge for now
 }
+
+#[cfg(all(feature = "verilator-only", not(feature = "cramium-mpw")))]
+pub fn coreuser_config() {
+    // configure coruser signals. Specific to NTO.
+    use utra::coreuser::*;
+    crate::println!("coreuser setup...");
+    let mut coreuser = CSR::new(utra::coreuser::HW_COREUSER_BASE as *mut u32);
+    // set to 0 so we can safely mask it later on
+    coreuser.wo(USERVALUE, 0);
+    coreuser.rmwf(utra::coreuser::USERVALUE_DEFAULT, 3);
+    let trusted_asids = [(1, 0), (2, 0), (3, 1), (4, 2), (1, 0), (1, 0), (1, 0), (1, 0)];
+    let asid_fields = [
+        (utra::coreuser::MAP_LO_LUT0, utra::coreuser::USERVALUE_USER0),
+        (utra::coreuser::MAP_LO_LUT1, utra::coreuser::USERVALUE_USER1),
+        (utra::coreuser::MAP_LO_LUT2, utra::coreuser::USERVALUE_USER2),
+        (utra::coreuser::MAP_LO_LUT3, utra::coreuser::USERVALUE_USER3),
+        (utra::coreuser::MAP_HI_LUT4, utra::coreuser::USERVALUE_USER4),
+        (utra::coreuser::MAP_HI_LUT5, utra::coreuser::USERVALUE_USER5),
+        (utra::coreuser::MAP_HI_LUT6, utra::coreuser::USERVALUE_USER6),
+        (utra::coreuser::MAP_HI_LUT7, utra::coreuser::USERVALUE_USER7),
+    ];
+    for (&(asid, value), (map_field, uservalue_field)) in trusted_asids.iter().zip(asid_fields) {
+        coreuser.rmwf(map_field, asid);
+        coreuser.rmwf(uservalue_field, value);
+    }
+    coreuser.rmwf(CONTROL_INVERT_PRIV, 1);
+    coreuser.rmwf(CONTROL_ENABLE, 1);
+
+    // turn off updates
+    coreuser.wo(utra::coreuser::PROTECT, 1);
+    crate::println!("coreuser locked!");
+}

loader/src/platform/cramium/link-soc.x

@@ -86,12 +86,12 @@ SECTIONS
     . = ALIGN(4);
     _edata = .;
   } > REGION_DATA AT > REGION_RODATA
-
+/*
   .fonts : ALIGN(65536)
   {
       KEEP(*(.fontdata));
   } > FONTS
-
+*/
   .bss (NOLOAD) :
   {
     _sbss = .;