Added sleep signals to rvfi documentation

docs/user_manual/source/rvfi.rst

@@ -54,6 +54,37 @@ The ``rvfi_dbg_mode`` signal is high if the instruction was executed in debug mo
 
 Whenever |corev| has a pending NMI, the ``rvfi_nmip`` will signal this. ``rvfi_nmip[0]`` will be 1 whenever an NMI is pending, while ``rvfi_nmip[1]`` will be 0 for loads and 1 for stores.
 
+
+**Sleep Signals**
+
+These signals report core sleep and wakeup information.
+
+.. code-block:: verilog
+
+   output rvfi_wu_t [NRET - 1 : 0] rvfi_wu
+   output logic     [NRET - 1 : 0] rvfi_sleep
+
+
+Where the rvfi_wu_t struct contains following fields:
+
+.. table:: RVFI wu type
+  :name: RVFI wu type
+
+  =================  ============  =======
+  Field              Type          Bits
+  =================  ============  =======
+  wu                 logic         [0]
+  interrupt          logic         [1]
+  debug              logic         [2]
+  cause              logic [10:0]  [13:3]
+  =================  ============  =======
+
+``rvfi_sleep`` is set on the last instruction before the core enters sleep mode.
+``rvfi_wu.wu`` is set for the first instruction executed after waking up.
+``rvfi_wu.interrupt`` is set if the wakeup was caused by an interrupt, and
+``rvfi_wu.debug`` is set if the wakeup was caused by a debug request.
+``rvfi_wu.cause`` signals the wakeup cause exception code.
+
 Compatibility
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