[chip dv] Support for running opentitan tock in dv

- Added runtime configurability for setting the uart baud rate
- Added `chip_opentitan_tock` as a nightly test
  - Set the knob to 0-initialize the RAM temporarily

Signed-off-by: Srikrishna Iyer <sriyer@google.com>
diff --git a/hw/top_earlgrey/dv/tests/chip_base_test.sv b/hw/top_earlgrey/dv/tests/chip_base_test.sv
index 0a8c9b4..b644fee 100644
--- a/hw/top_earlgrey/dv/tests/chip_base_test.sv
+++ b/hw/top_earlgrey/dv/tests/chip_base_test.sv
@@ -9,28 +9,34 @@
   `uvm_component_utils(chip_base_test)
   `uvm_component_new
 
-  // the base class dv_base_test creates the following instances:
+  // The base class dv_base_test creates the following instances:
   // chip_env_cfg: cfg
   // chip_env:     env
 
-  // the base class also looks up UVM_TEST_SEQ plusarg to create and run that seq in
-  // the run_phase; as such, nothing more needs to be done
+  // The base class also looks up UVM_TEST_SEQ plusarg to create and run that seq in
+  // the run_phase; as such, nothing more needs to be done.
 
   virtual function void build_phase(uvm_phase phase);
     super.build_phase(phase);
-    // knob to en/dis stubbing cpu (disabled by default)
+    // Knob to en/dis stubbing cpu (disabled by default).
     void'($value$plusargs("stub_cpu=%0b", cfg.stub_cpu));
     // Set tl_agent's is_active bit based on the retrieved stub_cpu value.
     cfg.m_tl_agent_cfg.is_active = cfg.stub_cpu;
 
-    // knob to enable logging via uart
+    // Knob to set the UART baud rate (set to 2M by default).
+    void'($value$plusargs("uart_baud_rate=%0d", cfg.uart_baud_rate));
+
+    // Knob to enable logging over UART (disabled by default).
     void'($value$plusargs("en_uart_logger=%0b", cfg.en_uart_logger));
     cfg.m_uart_agent_cfg.en_logger = cfg.en_uart_logger;
     cfg.m_uart_agent_cfg.logger_msg_id  = "SW_LOGS";
 
-    // Set the sw_test_timeout_ns knob from plusarg if available.
+    // Knob to set the sw_test_timeout_ns (set to 5ms by default).
     void'($value$plusargs("sw_test_timeout_ns=%0d", cfg.sw_test_timeout_ns));
 
+    // Knob to pre-initialize RAM to 0s (disabled by default).
+    void'($value$plusargs("initialize_ram=%0b", cfg.initialize_ram));
+
     // override tl_seq_item to apply constraint on source_id
     tl_seq_item::type_id::set_type_override(chip_tl_seq_item::get_type());
   endfunction : build_phase