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

`include "prim_assert.sv"


module clkmgr import clkmgr_pkg::*; (
  // Primary module clocks
  input clk_i,
  input rst_ni,
  input clk_main_i,
  input rst_main_ni,
  input clk_fixed_i,
  input rst_fixed_ni,
  input clk_usb_48mhz_i,
  input rst_usb_48mhz_ni,

  // Bus Interface
  input tlul_pkg::tl_h2d_t tl_i,
  output tlul_pkg::tl_d2h_t tl_o,

  // pwrmgr interface
  input pwrmgr_pkg::pwr_clk_req_t pwr_i,
  output pwrmgr_pkg::pwr_clk_rsp_t pwr_o,

  // dft interface
  input clk_dft_t dft_i,

  // idle hints
  input clk_hint_status_t status_i,

  // clock output interface
  output clkmgr_out_t clocks_o

);

  ////////////////////////////////////////////////////
  // Register Interface
  ////////////////////////////////////////////////////

  clkmgr_reg_pkg::clkmgr_reg2hw_t reg2hw;
  clkmgr_reg_pkg::clkmgr_hw2reg_t hw2reg;

  clkmgr_reg_top i_reg (
    .clk_i,
    .rst_ni,
    .tl_i,
    .tl_o,
    .reg2hw,
    .hw2reg,
    .devmode_i(1'b1)
  );

  ////////////////////////////////////////////////////
  // Power up group - feedthrough
  ////////////////////////////////////////////////////

  assign clocks_o.clk_fixed_powerup = clk_fixed_i;
  assign clocks_o.clk_main_powerup = clk_main_i;
  assign clocks_o.clk_usb_48mhz_powerup = clk_usb_48mhz_i;

  ////////////////////////////////////////////////////
  // Root gating
  ////////////////////////////////////////////////////

  // the rst_ni connection below is incorrect, need to find a proper reset in the sequence to use
  // if the clkmgr is always on, can use por synced directly
  // if not, then need to generate something ahead of lc/sys

  logic async_roots_en;
  logic roots_en_q2, roots_en_q1, roots_en_d;
  logic clk_main_root;
  logic clk_main_en;
  logic clk_fixed_root;
  logic clk_fixed_en;
  logic clk_usb_48mhz_root;
  logic clk_usb_48mhz_en;

  prim_clock_gating_sync i_main_sync (
    .clk_i(clk_main_i),
    .rst_ni(rst_main_ni),
    .test_en_i(dft_i.test_en),
    .async_en_i(pwr_i.ip_clk_en),
    .en_o(clk_main_en),
    .clk_o(clk_main_root)
  );
  prim_clock_gating_sync i_fixed_sync (
    .clk_i(clk_fixed_i),
    .rst_ni(rst_fixed_ni),
    .test_en_i(dft_i.test_en),
    .async_en_i(pwr_i.ip_clk_en),
    .en_o(clk_fixed_en),
    .clk_o(clk_fixed_root)
  );
  prim_clock_gating_sync i_usb_48mhz_sync (
    .clk_i(clk_usb_48mhz_i),
    .rst_ni(rst_usb_48mhz_ni),
    .test_en_i(dft_i.test_en),
    .async_en_i(pwr_i.ip_clk_en),
    .en_o(clk_usb_48mhz_en),
    .clk_o(clk_usb_48mhz_root)
  );

  // an async OR of all the synchronized enables
  assign async_roots_en =
    clk_main_en |
    clk_fixed_en |
    clk_usb_48mhz_en;

  // Sync the OR back into clkmgr domain for feedback to pwrmgr.
  // Since the signal is combo / converged on the other side, de-bounce
  // the signal prior to output
  prim_flop_2sync #(
    .Width(1)
  ) i_roots_en_sync (
    .clk_i,
    .rst_ni,
    .d(async_roots_en),
    .q(roots_en_d)
  );

  always_ff @(posedge clk_i or negedge rst_ni) begin
    if (!rst_ni) begin
      roots_en_q1 <= 1'b0;
      roots_en_q2 <= 1'b0;
    end else begin
      roots_en_q1 <= roots_en_d;

      if (roots_en_q1 == roots_en_d) begin
        roots_en_q2 <= roots_en_q1;
      end
    end
  end

  assign pwr_o.roots_en = roots_en_q2;

  ////////////////////////////////////////////////////
  // Clocks with only root gate
  ////////////////////////////////////////////////////
  assign clocks_o.clk_main_infra = clk_main_root;
  assign clocks_o.clk_fixed_infra = clk_fixed_root;
  assign clocks_o.clk_fixed_secure = clk_fixed_root;
  assign clocks_o.clk_main_secure = clk_main_root;
  assign clocks_o.clk_fixed_timers = clk_fixed_root;
  assign clocks_o.clk_proc_main = clk_main_root;

  ////////////////////////////////////////////////////
  // Software direct control group
  ////////////////////////////////////////////////////

  // the rst_ni connection below is incorrect, need to find a proper reset in the sequence to use
  // if the clkmgr is always on, can use por synced directly
  // if not, then need to generate something ahead of lc/sys

  prim_clock_gating_sync i_clk_fixed_peri_sync (
    .clk_i(clk_fixed_root),
    .rst_ni(rst_fixed_ni),
    .test_en_i(dft_i.test_en),
    .async_en_i(reg2hw.clk_enables.clk_fixed_peri_en.q),
    .en_o(), // should this be fedback for software?
    .clk_o(clocks_o.clk_fixed_peri)
  );
  prim_clock_gating_sync i_clk_usb_48mhz_peri_sync (
    .clk_i(clk_usb_48mhz_root),
    .rst_ni(rst_usb_48mhz_ni),
    .test_en_i(dft_i.test_en),
    .async_en_i(reg2hw.clk_enables.clk_usb_48mhz_peri_en.q),
    .en_o(), // should this be fedback for software?
    .clk_o(clocks_o.clk_usb_48mhz_peri)
  );

  ////////////////////////////////////////////////////
  // Software hint group
  // The idle hint feedback is assumed to be synchronous to the
  // clock target
  ////////////////////////////////////////////////////

  // the rst_ni connection below is incorrect, need to find a proper reset in the sequence to use
  // if the clkmgr is always on, can use por synced directly
  // if not, then need to generate something ahead of lc/sys

  logic clk_main_aes_hint;
  logic clk_main_aes_en;
  logic clk_main_hmac_hint;
  logic clk_main_hmac_en;

  assign clk_main_aes_en = clk_main_aes_hint | ~status_i.idle[0];

  prim_flop_2sync #(
    .Width(1)
  ) i_clk_main_aes_hint_sync (
    .clk_i(clk_main_root),
    .rst_ni(rst_main_ni),
    .d(reg2hw.clk_hints.clk_main_aes_hint.q),
    .q(clk_main_aes_hint)
  );

  prim_clock_gating i_clk_main_aes_sync (
    .clk_i(clk_main_root),
    .en_i(clk_main_aes_en),
    .test_en_i(dft_i.test_en),
    .clk_o(clocks_o.clk_main_aes)
  );

  assign clk_main_hmac_en = clk_main_hmac_hint | ~status_i.idle[1];

  prim_flop_2sync #(
    .Width(1)
  ) i_clk_main_hmac_hint_sync (
    .clk_i(clk_main_root),
    .rst_ni(rst_main_ni),
    .d(reg2hw.clk_hints.clk_main_hmac_hint.q),
    .q(clk_main_hmac_hint)
  );

  prim_clock_gating i_clk_main_hmac_sync (
    .clk_i(clk_main_root),
    .en_i(clk_main_hmac_en),
    .test_en_i(dft_i.test_en),
    .clk_o(clocks_o.clk_main_hmac)
  );


  // state readback
  assign hw2reg.clk_hints_status.clk_main_aes_val.de = 1'b1;
  assign hw2reg.clk_hints_status.clk_main_aes_val.d = clk_main_aes_en;
  assign hw2reg.clk_hints_status.clk_main_hmac_val.de = 1'b1;
  assign hw2reg.clk_hints_status.clk_main_hmac_val.d = clk_main_hmac_en;


  ////////////////////////////////////////////////////
  // Assertions
  ////////////////////////////////////////////////////


endmodule // rstmgr