targets: add implementation for Tillitis TKey device (#4631)

* initial implementation for Tillitis TKey device
* add UART implementation for TKey
* add Pin interface implementation for TKey touch sensor
* add RNG interface implementation for TKey
* add helpful machine package functions to return identifiers such as name and version for TKey
* use built-in timer for sleep timing on TKey
* modify UART implementation for TKey to implement Serialer interface
* implement BLAKE2s ROM function call for TKey device
* handle abort by triggering TKey device fault using illegal instruction to halt CPU
* simplify TKey implementation by inheriting from existing riscv32 target
* return error for trying to configure invalid baudrates on UART
* add tkey to builder test
* be very specific for features passed to LLVM for specific config in use for TKey
* handle feedback items from TKey device code review

Signed-off-by: deadprogram <ron@hybridgroup.com>

targets/tkey.json

@@ -0,0 +1,13 @@
+{
+    "inherits": ["riscv32"],
+    "build-tags": ["tkey"],
+    "features": "+32bit,+c,+zmmul,-a,-d,-e,-experimental-zacas,-experimental-zcmop,-experimental-zfbfmin,-experimental-zicfilp,-experimental-zicfiss,-experimental-zimop,-experimental-ztso,-experimental-zvfbfmin,-experimental-zvfbfwma,-f,-h,-m,-relax,-smaia,-smepmp,-ssaia,-svinval,-svnapot,-svpbmt,-v,-xcvalu,-xcvbi,-xcvbitmanip,-xcvelw,-xcvmac,-xcvmem,-xcvsimd,-xsfvcp,-xsfvfnrclipxfqf,-xsfvfwmaccqqq,-xsfvqmaccdod,-xsfvqmaccqoq,-xtheadba,-xtheadbb,-xtheadbs,-xtheadcmo,-xtheadcondmov,-xtheadfmemidx,-xtheadmac,-xtheadmemidx,-xtheadmempair,-xtheadsync,-xtheadvdot,-xventanacondops,-za128rs,-za64rs,-zawrs,-zba,-zbb,-zbc,-zbkb,-zbkc,-zbkx,-zbs,-zca,-zcb,-zcd,-zce,-zcf,-zcmp,-zcmt,-zdinx,-zfa,-zfh,-zfhmin,-zfinx,-zhinx,-zhinxmin,-zic64b,-zicbom,-zicbop,-zicboz,-ziccamoa,-ziccif,-zicclsm,-ziccrse,-zicntr,-zicond,-zicsr,-zifencei,-zihintntl,-zihintpause,-zihpm,-zk,-zkn,-zknd,-zkne,-zknh,-zkr,-zks,-zksed,-zksh,-zkt,-zvbb,-zvbc,-zve32f,-zve32x,-zve64d,-zve64f,-zve64x,-zvfh,-zvfhmin,-zvkb,-zvkg,-zvkn,-zvknc,-zvkned,-zvkng,-zvknha,-zvknhb,-zvks,-zvksc,-zvksed,-zvksg,-zvksh,-zvkt,-zvl1024b,-zvl128b,-zvl16384b,-zvl2048b,-zvl256b,-zvl32768b,-zvl32b,-zvl4096b,-zvl512b,-zvl64b,-zvl65536b,-zvl8192b",
+    "cflags": [
+        "-march=rv32iczmmul"
+    ],
+    "linkerscript": "targets/tkey.ld",
+    "scheduler": "none",
+    "gc": "leaking",
+    "flash-command": "tkey-runapp {bin}",
+    "serial": "uart"
+}

targets/tkey.ld

@@ -0,0 +1,11 @@
+
+MEMORY
+{
+    RAM (rwx)       : ORIGIN = 0x40000000, LENGTH = 0x20000 /* 128 KB */
+}
+
+REGION_ALIAS("FLASH_TEXT", RAM);
+
+_stack_size = 2K;
+
+INCLUDE "targets/riscv.ld"