// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

{ name: "kmac"
  clock_primary: "clk_i"
  bus_device: "tlul"
  bus_host: "none"

  interrupt_list: [
    { name: "kmac_done"
      desc: "KMAC/SHA3 absorbing has been completed"
    }
    { name: "fifo_empty"
      desc: "Message FIFO empty condition"
    }
    { name: "kmac_err"
      desc: "KMAC/SHA3 error occurred. ERR_CODE register shows the details"
    }
  ]
  alert_list: []
  param_list: [
    { name:    "EnMasking"
      type:    "int"
      default: "0"
      desc:    '''
        Disable(0) or enable(1) first-order masking of Keccak round.

        If masking is enabled, ReuseShare parameter will impact the design.
        '''
      local:   "false"
      expose:  "true"
    }
    { name:    "ReuseShare"
      type:    "int"
      default: "0"
      desc:    '''
        If enabled (1), the internal Keccak round logic will re-use the
        adjacent shares as entropy in Domain-Oriented Masking AND logic.
        It improves the throughput of Keccak, as it only requires small
        amount of entropy rather than 1600 bit per round.

        This feature is not implemented yet.
        '''
      local:   "false"
      expose:  "true"
    }
    { name:    "NumWordsKey"
      type:    "int"
      default: "16"
      desc:    "Number of words for the secret key"
      local:   "true"
    }
    { name:    "NumWordsPrefix"
      type:    "int"
      default: "11"
      desc:    "Number of words for Encoded NsPrefix."
      local:   "true"
    }
  ]
  regwidth: "32"
  registers: [
    { name: "CFG"
      desc: '''KMAC Configuration register.

            This register is  updated when the hashing engine is in Idle.
            If the software updates the register while the engine computes, the
            updated value will be discarded.
            '''
      regwen: "CFG_REGWEN"
      swaccess: "rw"
      hwaccess: "hrw"
      fields: [
        { bits: "0"
          name: "kmac_en"
          desc: '''KMAC datapath enable.

                If this bit is 1, the incoming message is processed in KMAC
                with the secret key.
                '''
          tags: [// don't enable kmac and sha data paths - we will do that in functional tests
                 "excl:CsrNonInitTests:CsrExclWrite"]
        } // f: kmac_en
        { bits: "3:1"
          name: "strength"
          desc: '''Hashing Strength

                3 bit field to select the security strength of SHA3 hashing
                engine. If mode field is set to SHAKE or cSHAKE, only 128 and
                256 strength can be selected. Other value will result error
                when hashing starts.
                '''
          enum: [
            { value: "0"
              name:  "L128"
              desc: "128 bit strength. Keccak rate is 1344 bit"
            }
            { value: "1"
              name:  "L224"
              desc: "224 bit strength. Keccak rate is 1152 bit"
            }
            { value: "2"
              name:  "L256"
              desc: "256 bit strength. Keccak rate is 1088 bit"
            }
            { value: "3"
              name:  "L384"
              desc: "384 bit strength. Keccak rate is 832 bit"
            }
            { value: "4"
              name:  "L512"
              desc: "512 bit strength. Keccak rate is 576 bit"
            }
          ]
        } // f: strength
        { bits: "5:4"
          name: "mode"
          desc: '''Keccak hashing mode.

                This module supports SHA3 main hashing algorithm and the part
                of its derived functions, SHAKE and cSHAKE with limitations.
                This field is to select the mode.
                '''
          enum: [
            { value: "0"
              name: "SHA3"
              desc: "SHA3 hashing mode. It appends `2'b 10` to the end of msg"
            }
            { value: "2"
              name: "SHAKE"
              desc: "SHAKE hashing mode. It appends `1111` to the end of msg"
            }
            { value: "3"
              name: "cSHAKE"
              desc: "cSHAKE hashing mode. It appends `00` to the end of msg"
            }
          ]
        } // f: mode
        { bits: "8"
          name: "msg_endianness"
          desc: '''Message and Secret Key Endianness.

                Convert TL-UL write data[31:0] to big-endian style
                {d[7:0], d[15:8], ...}

                0: Little-endian. Keep input value as it is
                1: Big-endian. Convert incoming value
                '''
          resval: "1"
        } // f: msg_endianness
        { bits: "9"
          name: "state_endianness"
          desc: '''Output state (Digest) Endianness.

                Convert read-out state register to big-endian style.
                If 0, keep the internal value as it is when SW reads.
                If 1, convert the internal state value.
                '''
        } // f: state_endianness
      ]
    } // R: CFG
    { name: "CMD"
      desc: '''KMAC/ SHA3 command register.

            This register is to control the KMAC to start accepting message,
            to process the message, and to manually run additional keccak
            rounds at the end. Only at certain stage, the CMD affects to the
            control logic. It follows the sequence of

            `start` --> `process` --> {`run` if needed --> } `done`
            '''
      swaccess: "r0w1c"
      hwaccess: "hro"
      hwext: "true"
      hwqe:  "true"
      tags: [// design assertion : after start sets, can only wr msg or set process
             // design assertion : process can be set only after start is set
             "excl:CsrAllTests:CsrExclWrite"]
      fields: [
        { bits: "0"
          name: "start"
          desc: '''If writes 1 into this field when KMAC/SHA3 is in idle,
                KMAC/SHA3 begins its operation.

                If the mode is cSHAKE, before receiving the message, the
                hashing logic processes Function name string N and
                customization input string S first. If KMAC mode is enabled,
                additionally it processes secret key block.
                '''
        } // f: start
        { bits: "1"
          name: "process"
          desc: '''If writes 1 into this field when KMAC/SHA3 began its
                operation and received the entire message, it computes the
                digest or signing.
                '''
        } // f: process
        { bits: "2"
          name: "run"
          desc: '''The `run` field is used in the sponge squeezing stage.
                It triggers the keccak round logic to run full 24 rounds.
                This is optional and used when software needs more digest bits
                than the keccak rate.

                It only affects when the kmac/sha3 operation is completed.
                '''
        } // f: run
        { bits: "3"
          name: "done"
          desc: '''If writes 1 into this field when KMAC/SHA3 squeezing is
                completed. KMAC/SHA3 hashing engine clears internal varaibles
                and goes back to Idle state for next command.
                '''
        } // f: done
      ]
    } // R: CMD
    { name: "STATUS"
      desc: '''KMAC/SHA3 Status register.'''
      swaccess: "ro"
      hwaccess: "hwo"
      hwext: "true"
      fields: [
        { bits: "0"
          name: "sha3_idle"
          desc: "If 1, SHA3 hashing engine is in idle state."
          resval: "1"
        }
        { bits: "1"
          name: "sha3_absorb"
          desc: "If 1, SHA3 is receiving message stream and processing it"
        }
        { bits: "2"
          name: "sha3_squeeze"
          desc: '''If 1, SHA3 completes sponge absorbing stage.
                In this stage, SW can manually run the hashing engine.
                '''
        }
        { bits: "12:8"
          name: "fifo_depth"
          desc: "Message FIFO entry count"
        }
        { bits: "14"
          name: "fifo_empty"
          desc: "Message FIFO Empty indicator"
          resval: "1"
        }
        { bits: "15"
          name: "fifo_full"
          desc: "Message FIFO Full indicator"
        }
      ]
    } // R: STATUS
    { multireg: {
        name: "KEY_SHARE0"
        desc: '''KMAC Secret Key

              KMAC secret key can be up to 512 bit.
              Order of the secret key is:
              key[512:0] = {KEY15, KEY14, ... , KEY0};

              The registers are allowed to be updated when the engine is in Idle state.
              If the engine computes the hash, it discards any attempts to update the secret keys
              and report an error.

              Current KMAC supports up to 512 bit secret key. It is the sw
              responsibility to keep upper bits of the secret key to 0.
              '''
        count: "NumWordsKey"
        cname: "KMAC"
        hwext: "true"
        hwqe : "true"
        swaccess: "wo"
        hwaccess: "hro"
        fields: [
          { bits: "31:0"
            name: "key"
            desc: "32-bit chunk of up-to 512-bit Secret Key"
          }
        ]
      } // R: KEY_SHARE0
    } // multireg: KEY_SHARE0
    { multireg: {
        name: "KEY_SHARE1"
        desc: '''KMAC Secret Key, 2nd share.

              KMAC secret key can be up to 512 bit.
              Order of the secret key is:
              key[512:0] = {KEY15, KEY14, ... , KEY0};

              The registers are allowed to be updated when the engine is in Idle state.
              If the engine computes the hash, it discards any attempts to update the secret keys
              and report an error.

              Current KMAC supports up to 512 bit secret key. It is the sw
              responsibility to keep upper bits of the secret key to 0.
              '''
        count: "NumWordsKey"
        cname: "KMAC"
        hwext: "true"
        hwqe : "true"
        swaccess: "wo"
        hwaccess: "hro"
        fields: [
          { bits: "31:0"
            name: "key"
            desc: "32-bit chunk of up-to 512-bit Secret Key"
          }
        ]
      } // R: KEY_SHARE1
    } // multireg: KEY_SHARE1
    { name: "KEY_LEN"
      desc: '''Secret Key length in bit.

            This value is used to make encoded secret key in KMAC.
            '''
      regwen: "CFG_REGWEN"
      swaccess: "wo"
      hwaccess: "hro"
      hwext: "false"
      fields: [
        { bits: "2:0"
          name: "len"
          desc: "Length in bits"
          enum: [
            { value: "0"
              name:  "Key128"
              desc: "Key length is 128 bit."
            }
            { value: "1"
              name:  "Key192"
              desc: "Key length is 192 bit."
            }
            { value: "2"
              name:  "Key256"
              desc: "Key length is 256 bit."
            }
            { value: "3"
              name:  "Key384"
              desc: "Key length is 384 bit."
            }
            { value: "4"
              name:  "Key512"
              desc: "Key length is 512 bit."
            }
          ]
        } // f : len
      ]
    } // R : KEY_LEN
    { multireg: {
        name: "PREFIX"
        desc: '''cSHAKE Prefix register.

              Prefix including Function Name N and Customization String S.
              The SHA3 assumes this register value is encoded as:
              `encode_string(N) || encode_string(S) || 0`. It means that the
              software can freely decide the length of N or S based on the
              given Prefix register size 320bit. 320bit is determined to have
              32-bit of N and up to 256-bit of S + encode of their length.

              It is SW responsibility to fill the register with encoded value
              that is described at Section 2.3.2 String Encoding in NIST SP
              800-185 specification.

              Order of Prefix is:
              prefix[end:0] := {PREFIX0, PREFIX1, ... }

              The registers are allowed to be updated when the engine is in Idle state.
              If the engine computes the hash, it discards any attempts to update the secret keys
              and report an error.
              '''
        count: "NumWordsPrefix"
        cname: "KMAC"
        hwext: "false"
        hwqe : "true"
        swaccess: "rw"
        hwaccess: "hro"
        fields: [
          { bits: "31:0"
            name: "prefix"
            desc: "32-bit chunk of Encoded NS Prefix"
          }
        ]
      } // R: PREFIX
    } // multireg: PREFIX
    { name: "ERR_CODE"
      desc: "KMAC/SHA3 Error Code",
      swaccess: "ro",
      hwaccess: "hwo",
      fields: [
        { bits: "31:0",
          name: "err_code",
          desc: '''If error interrupt occurs, this register has information of error cause.
                Please take a look at `hw/ip/kmac/rtl/kmac_pkg.sv:err_code_e enum type.
                '''
          tags: [// Randomly write mem will cause this reg updated by design
                 "excl:CsrNonInitTests:CsrExclCheck"]
        }
      ]
    } // R: ERR_CODE
    { name: "CFG_REGWEN"
      desc: '''Controls the configurability of !!CFG register.

            This register ensures the contents of !!CFG register cannot be
            changed by the software while the KMAC/SHA3 is in operation mode.
            '''
      swaccess: "ro"
      hwaccess: "hwo"
      hwext: "true"
      fields: [
        { bits: "0"
          name: "en"
          desc: "Configuration enable."
          resval: "1"
        } // f : en 
      ]
      tags: [// This regwen is completely under HW management and thus cannot be manipulated
             // by software.
             "excl:CsrNonInitTests:CsrExclCheck"]
    } // R : CFG_REGWEN

    { skipto: "0x400"}
    { window: {
        name: "STATE"
        items: "128"  // 512B address space
        swaccess: "ro"
        desc: '''Keccak State (1600 bit) memory.

              The software can get the processed digest by reading this memory
              region. Unlike MSG_FIFO, STATE memory space sees the addr[9:0].
              If Masking feature is enabled, the software reads two shares from
              this memory space.

              0x400 - 0x4C7: STATE or first share of STATE if Masking = 1
              0x500 - 0x5C7: 0 or second share of STATE if Masking = 1
              '''
      }
    } // W: STATE

    { skipto: "0x800"}

    { window: {
        name: "MSG_FIFO"
        items: "512"     // 2kB range
        swaccess: "wo"
        byte-write: "true"
        desc: '''Message FIFO.

              Any write to this window will be appended to the FIFO. Only lower
              2 bits `[1:0]` of the address matter to writes within the window
              in order to handle with sub-word writes.
              '''
      }
    } // W: MSG_FIFO
  ]
}