///////////////////////////////////////////
// pmachecker.sv
//
// Written: tfleming@hmc.edu & jtorrey@hmc.edu 20 April 2021
// Modified: 
//
// Purpose: Examines all physical memory accesses and identifies attributes of
//          the memory region accessed.
//          Can report illegal accesses to the trap unit and cause a fault.
// 
// A component of the Wally configurable RISC-V project.
// 
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, 
// modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software 
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT 
// OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
///////////////////////////////////////////

`include "wally-config.vh"

module pmachecker (
//  input  logic        clk, reset, // *** unused in this module and all sub modules.

  input  logic [`PA_BITS-1:0] PhysicalAddress,
  input  logic [1:0]          Size,
  input  logic [31:0] HADDR,
  input  logic [2:0]  HSIZE,
//  input  logic [2:0]  HBURST, //  *** in AHBlite, HBURST is hardwired to zero for single bursts only allowed. consider removing from this module if unused.

  input  logic        AtomicAccessM, ExecuteAccessF, WriteAccessM, ReadAccessM, // *** atomicaccessM is unused but might want to stay in for future use.

  output logic        Cacheable, Idempotent, AtomicAllowed,
  output logic        PMASquashBusAccess,

  output logic [5:0]  HSELRegions,

  output logic        PMAInstrAccessFaultF,
  output logic        PMALoadAccessFaultM,
  output logic        PMAStoreAccessFaultM
);

  // logic BootTim, Tim, CLINT, GPIO, UART, PLIC;
  logic PMAAccessFault;
  logic AccessRW, AccessRWX, AccessRX;

  // Determine what type of access is being made
  assign AccessRW = ReadAccessM | WriteAccessM;
  assign AccessRWX = ReadAccessM | WriteAccessM | ExecuteAccessF;
  assign AccessRX = ReadAccessM | ExecuteAccessF;

  // Determine which region of physical memory (if any) is being accessed
  // *** linux tests fail early when Access is anything other than 1b1
  pmaadrdec boottimdec(HADDR, `BOOTTIM_BASE, `BOOTTIM_RANGE, `BOOTTIM_SUPPORTED, 1'b1/*AccessRX*/, HSIZE, 4'b1111, HSELRegions[5]);
  pmaadrdec timdec(HADDR, `TIM_BASE, `TIM_RANGE, `TIM_SUPPORTED, 1'b1/*AccessRWX*/, HSIZE, 4'b1111, HSELRegions[4]);
  pmaadrdec clintdec(HADDR, `CLINT_BASE, `CLINT_RANGE, `CLINT_SUPPORTED, AccessRW, HSIZE, 4'b1111, HSELRegions[3]);
  pmaadrdec gpiodec(HADDR, `GPIO_BASE, `GPIO_RANGE, `GPIO_SUPPORTED, AccessRW, HSIZE, 4'b0100, HSELRegions[2]);
  pmaadrdec uartdec(HADDR, `UART_BASE, `UART_RANGE, `UART_SUPPORTED, AccessRW, HSIZE, 4'b0001, HSELRegions[1]);
  pmaadrdec plicdec(HADDR, `PLIC_BASE, `PLIC_RANGE, `PLIC_SUPPORTED, AccessRW, HSIZE, 4'b0100, HSELRegions[0]);

  // Only RAM memory regions are cacheable
  assign Cacheable = HSELRegions[5] | HSELRegions[4];
  assign Idempotent = HSELRegions[4];
  assign AtomicAllowed = HSELRegions[4];

  // Detect access faults
  assign PMAAccessFault = (~|HSELRegions)  && AccessRWX;  
  assign PMAInstrAccessFaultF = ExecuteAccessF && PMAAccessFault;
  assign PMALoadAccessFaultM  = ReadAccessM    && PMAAccessFault;
  assign PMAStoreAccessFaultM = WriteAccessM   && PMAAccessFault;
  assign PMASquashBusAccess = PMAAccessFault;
endmodule