// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0
//
# AES register template
{
  name: "aes",
  clock_primary: "clk_i",
  bus_device: "tlul",
  regwidth: "32",
  # Note: All parameters are local, they are not actually configurable.
  # Selecting values different from the default values below might cause undefined behavior.
  param_list: [
    { name:    "NumRegsKey",
      type:    "int",
      default: "8",
      desc:    "Number registers for key",
      local:   "true"
    },
    { name:    "NumRegsIv",
      type:    "int",
      default: "4",
      desc:    "Number registers for initialization vector",
      local:   "true"
    }
    { name:    "NumRegsData",
      type:    "int",
      default: "4",
      desc:    "Number registers for input and output data",
      local:   "true"
    }
  ],
  registers: [
##############################################################################
# initial key registers
    { multireg: {
      name: "KEY",
      desc: '''
        Initial Key Registers.
        Loaded into the internal Full Key register upon starting encryption/decryption of the next block.
        All key registers must be written at least once when the key is changed, regardless of key length (write random data for unused bits).
        The order in which the registers are updated does not matter.
        Can only be updated when the AES unit is idle.
        If the AES unit is non-idle, writes to these registers are ignored.
      '''
      count: "NumRegsKey",
      cname: "KEY",
      swaccess: "wo",
      hwaccess: "hrw",
      hwext:    "true",
      hwqe:     "true",
      fields: [
        { bits: "31:0", name: "key", desc: "Initial Key" }
      ],
      }
    },
##############################################################################
# initialization vector registers
    { multireg: {
      name: "IV",
      desc: '''
        Initialization Vector Registers.
        The initialization vector (IV) or initial counter value must be written to these registers when starting a new message in CBC or CTR mode (see Control Register), respectively.
        In CBC and CTR modes, the AES unit does not start encryption/decryption with a partially updated IV.
        Each register has to be written at least once.
        The order in which the registers are written does not matter.
        If the AES unit is non-idle, writes to these registers are ignored.
        Whenever starting a new message, the corresponding IV value must be provided by the processor.
        Once started, the AES unit automatically updates the contents of these registers.
        In ECB mode, the IV registers are not used and do not need to be configured.
      '''
      count: "NumRegsIv",
      cname: "IV",
      swaccess: "wo",
      hwaccess: "hrw",
      hwext:    "true",
      hwqe:     "true",
      fields: [
        { bits: "31:0", name: "iv", desc: "Initialization Vector" }
      ],
      }
    },
##############################################################################
# input data registers
    { multireg: {
      name: "DATA_IN",
      desc: '''
        Input Data Registers.
        If MANUAL_OPERATION=0 (see Control Register), the AES unit automatically starts encryption/decryption after these register have been written.
        Each register has to be written at least once.
        The order in which the registers are written does not matter.
        Loaded into the internal State register upon starting encryption/decryption of the next block.
        After that, the processor can update the Input Data Register.
      '''
      count: "NumRegsData",
      cname: "DATA_IN",
      swaccess: "wo",
      hwaccess: "hrw",
      hwqe:     "true",
      fields: [
        { bits: "31:0", name: "data_in", desc: "Input Data" }
      ],
      }
    },
##############################################################################
# output data registers
    { multireg: {
      name: "DATA_OUT",
      desc: '''
        Output Data Register.
        Holds the output data produced by the AES unit during the last encryption/decryption operation.
        If MANUAL_OPERATION=0 (see Control Register), the AES unit is stalled when the previous output data has not yet been read and is about to be overwritten.
        Each register has to be read at least once.
        The order in which the registers are read does not matter.
      '''
      count: "NumRegsData",
      cname: "DATA_OUT",
      swaccess: "ro",
      hwaccess: "hrw",
      hwext:    "true",
      hwre:     "true",
      fields: [
        { bits: "31:0", name: "data_out", desc: "Output Data" }
      ]
      tags: [// Updated by the HW.
             // Updates based on writes to other regs.
             // No reset but sync clear with random data.
             // Exclude from init and write-read checks.
             "excl:CsrAllTests:CsrExclCheck"]
      }
    },
##############################################################################
# control and status registers
  { name: "CTRL",
    desc: '''
      Control Register. Can only be updated when the AES unit is idle. If the
      AES unit is non-idle, writes to this register are ignored.
    '''
    swaccess: "rw",
    hwaccess: "hrw",
    hwext:    "true",
    hwqe:     "true",
    fields: [
      { bits: "0",
        name: "OPERATION",
        desc:  '''
          Select encryption(0) or decryption(1) operation of AES unit.
        '''
      }
      { bits: "3:1",
        name: "MODE",
        resval: "1",
        hwaccess: "hrw",
        desc:  '''
          3-bit one-hot field to select AES block cipher mode: ECB (3'b001), CBC (3'b010) or CTR (3'b100).
          Invalid input values, i.e., value with multiple bits set, and value 3'b000 are not supported are mapped to 3'b001.
        '''
      }
      { bits: "6:4",
        name: "KEY_LEN",
        resval: "1",
        hwaccess: "hrw",
        desc:  '''
          3-bit one-hot field to select AES key length: 128 bit (3'b001), 192 bit (3'b010)
          or 256 bit (3'b100). Invalid input values, i.e., value with multiple bits set,
          value 3'b000, and value 3'b010 in case 192-bit keys are not supported (because
          disabled at compile time) are mapped to 3'b001.
        '''
      }
      { bits: "7",
        name: "MANUAL_OPERATION",
        desc:  '''
          Controls whether the AES unit is operated in normal/automatic mode (0) or fully manual mode (1).
          In automatic mode (0), the AES unit automatically i) starts to encrypt/decrypt when it receives new input data, and ii) stalls during the last encryption/decryption cycle if the previous output data has not yet been read.
          This is the most efficient mode to operate in.
          In manual mode (1), the AES unit i) only starts to encrypt/decrypt after receiving a start trigger (see Trigger Register), and ii) overwrites previous output data irrespective of whether it has been read out or not.
          This mode is useful if software needs full control over the AES unit.
        '''
      }
    ]
    tags: [// Updated by the HW.
           // Updates based on writes to this reg (reset test possible).
           // Exclude from write-read checks.
           "excl:CsrNonInitTests:CsrExclWriteCheck"]
  },
  { name: "TRIGGER",
    desc: '''
      Trigger Register.
      Each bit is individually cleared to zero when executing the corresponding trigger.

    '''
    swaccess: "wo",
    hwaccess: "hrw",
    # Tag info (CSR test exclusions):
    #  Updated by the HW.
    #  Updates based on writes to this reg.
    #  -> Exclude all fields from write-read checks.
    #  Upon reset, the non-zero values trigger internal operations that clear this reg to zero.
    #  -> Exclude fields with non-zero reset value from init and write-read checks (also in reset test).
    fields: [
      { bits: "0",
        name: "START",
        desc:  '''
          Keep AES unit paused (0) or trigger the encryption/decryption of one data block (1).
          This trigger is ignored if MANUAL_OPERATION=0 (see Control Register).
        '''
        tags: ["excl:CsrNonInitTests:CsrExclWriteCheck"]
      }
      { bits: "1",
        name: "KEY_CLEAR",
        resval: "1"
        desc:  '''
          Keep current values in Initial Key, internal Full Key and Decryption Key registers (0)
          or clear those registers with pseudo-random data (1).
        '''
        tags: ["excl:CsrAllTests:CsrExclCheck"]
      }
      { bits: "2",
        name: "IV_CLEAR",
        resval: "1"
        desc:  '''
          Keep current values in IV registers (0) or clear those registers with pseudo-random data (1).
        '''
        tags: ["excl:CsrAllTests:CsrExclCheck"]
      }
      { bits: "3",
        name: "DATA_IN_CLEAR",
        resval: "1"
        desc:  '''
          Keep current values in input registers (0) or clear those registers with pseudo-random data (1).
        '''
        tags: ["excl:CsrAllTests:CsrExclCheck"]
      }
      { bits: "4",
        name: "DATA_OUT_CLEAR",
        resval: "1"
        desc:  '''
          Keep current values in output registers (0) or clear those registers with pseudo-random data (1).
        '''
        tags: ["excl:CsrAllTests:CsrExclCheck"]
      }
      { bits: "5",
        name: "PRNG_RESEED",
        resval: "1"
        desc:  '''
          Keep continuing with the current internal state of the internal pseudo-random number generator (0) or perform a reseed of the internal state from the connected entropy source (1).
        '''
        tags: ["excl:CsrAllTests:CsrExclCheck"]
      }
    ]
  },
  { name: "STATUS",
    desc: "Status Register",
    swaccess: "ro",
    hwaccess: "hwo",
    # Tag info (CSR test exclusions):
    #  Updated by the HW.
    #  Updates based on writes to other regs.
    #  -> Exclude all fields from init and write-read checks.
    #  Upon reset, internal operations are triggered that temporarily change the IDLE field.
    #  -> Exclude IDLE field from init and write-read checks (also in reset test).
    fields: [
      { bits: "0",
        name: "IDLE",
        resval: "1",
        desc:  '''
          The AES unit is idle (1) or busy (0).
          This flag is `0` if one of the following operations is currently running: i) encryption/decryption, ii) register clearing or iii) PRNG reseeding.
          This flag is also `0` if an encryption/decryption is running but the AES unit is stalled.
        '''
        tags: ["excl:CsrAllTests:CsrExclCheck"]
      }
      { bits: "1",
        name: "STALL",
        desc:  '''
          The AES unit is not stalled (0) or stalled (1) because there is previous
          output data that must be read by the processor before the AES unit can
          overwrite this data.
          This flag not meaningful if MANUAL_OPERATION=1 (see Control Register).
        '''
        tags: ["excl:CsrNonInitTests:CsrExclCheck"]
      }
      { bits: "2",
        name: "OUTPUT_VALID",
        desc:  '''
          The AES unit has no valid output (0) or has valid output data (1).
        '''
        tags: ["excl:CsrNonInitTests:CsrExclCheck"]
      }
      { bits: "3",
        name: "INPUT_READY",
        resval: "1",
        desc:  '''
          The AES unit is ready (1) to receive new data input via the DATA_IN registers or
          the present values in the DATA_IN registers have not yet been loaded into the
          module (0).
        '''
        tags: ["excl:CsrNonInitTests:CsrExclCheck"]
      }
    ]
  },
  ],
}