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////////////////////////////////////////////////////////////////////////////////

//

// Filename:    busmaster.v

//

// Project:     CMod S6 System on a Chip, ZipCPU demonstration project

//

// Purpose:     

//

// Creator:     Dan Gisselquist, Ph.D.

//              Gisselquist Technology, LLC

//

////////////////////////////////////////////////////////////////////////////////

//

// Copyright (C) 2015-2016, Gisselquist Technology, LLC

//

// This program is free software (firmware): you can redistribute it and/or

// modify it under the terms of  the GNU General Public License as published

// by the Free Software Foundation, either version 3 of the License, or (at

// your option) any later version.

//

// This program is distributed in the hope that it will be useful, but WITHOUT

// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

// for more details.

//

// You should have received a copy of the GNU General Public License along

// with this program.  (It's in the $(ROOT)/doc directory, run make with no

// target there if the PDF file isn't present.)  If not, see

// <http://www.gnu.org/licenses/> for a copy.

//

// License:     GPL, v3, as defined and found on www.gnu.org,

//              http://www.gnu.org/licenses/gpl.html

//

//

////////////////////////////////////////////////////////////////////////////////

//

//

//

`include "builddate.v"

//

`define INCLUDE_ZIPPY

`define IMPLEMENT_ONCHIP_RAM

`ifndef VERILATOR

`define FANCY_ICAP_ACCESS

`endif

`define FLASH_ACCESS

`define DBG_SCOPE       // About 204 LUTs, at 2^6 addresses

// `define      COMPRESSED_SCOPE

`define INCLUDE_SECOND_TIMER

`define SECOND_TIMER_IS_WATCHDOG

// `define      INCLUDE_RTC     // About 90 LUTs

// `define      FULL_BUSERR_CALCULATION

`define INCLUDE_CPU_RESET_LOGIC

module  busmaster(i_clk, i_rst,

                i_rx_stb, i_rx_data, o_tx_stb, o_tx_data, i_tx_busy,

                        o_uart_cts,

                // The SPI Flash lines

                o_qspi_cs_n, o_qspi_sck, o_qspi_dat, i_qspi_dat, o_qspi_mod,

                // The board I/O

                i_btn, o_led, o_pwm, o_pwm_aux,

                // Keypad connections

                i_kp_row, o_kp_col,

                // UART control

                o_uart_setup,

                // GPIO lines

                i_gpio, o_gpio);

        parameter       BUS_ADDRESS_WIDTH=23, ZIP_ADDRESS_WIDTH=BUS_ADDRESS_WIDTH,

                        CMOD_ZIPCPU_RESET_ADDRESS=23'h480000,

                        ZA=ZIP_ADDRESS_WIDTH, BAW=BUS_ADDRESS_WIDTH; // 24bits->2,258,23b->2181

        input                   i_clk, i_rst;

        input                   i_rx_stb;

        input           [7:0]    i_rx_data;

        output  reg             o_tx_stb;

        output  reg     [7:0]    o_tx_data;

        input                   i_tx_busy;

        output  wire            o_uart_cts;

        // SPI flash control

        output  wire            o_qspi_cs_n, o_qspi_sck;

        output  wire    [3:0]    o_qspi_dat;

        input           [3:0]    i_qspi_dat;

        output  wire    [1:0]    o_qspi_mod;

        // Board I/O

        input           [1:0]    i_btn;

        output  wire    [3:0]    o_led;

        output  wire            o_pwm;

        output  wire    [1:0]    o_pwm_aux;

        // Keypad

        input           [3:0]    i_kp_row;

        output  wire    [3:0]    o_kp_col;

        // UART control

        output  wire    [29:0]   o_uart_setup;

        // GPIO liines

        input           [15:0]   i_gpio;

        output  wire    [15:0]   o_gpio;

        //

        //

        // Master wishbone wires

        //

        //

        wire            wb_cyc, wb_stb, wb_we, wb_stall, wb_ack, wb_err;

        wire    [31:0]   wb_data, wb_idata;

        wire    [(BAW-1):0]      wb_addr;

        wire    [5:0]            io_addr;

        assign  io_addr = {

                        wb_addr[22],    // Flash

                        wb_addr[13],    // RAM

                        wb_addr[11],    // RTC

                        wb_addr[10],    // CFG

                        wb_addr[ 9],    // SCOPE

                        wb_addr[ 8] };  // I/O

        // Wires going to devices

        // And then headed back home

        wire    w_interrupt;

        // Oh, and the debug control for the ZIP CPU

        wire            zip_dbg_ack, zip_dbg_stall;

        wire    [31:0]   zip_dbg_data;

        //

        //

        // The BUS master (source): The ZipCPU

        //

        //

        wire            zip_cyc, zip_stb, zip_we, zip_cpu_int;

        wire    [(ZA-1):0]       w_zip_addr;

        wire    [(BAW-1):0]      zip_addr;

        wire    [31:0]           zip_data, zip_scope_data;

        // and then coming from devices

        wire            zip_ack, zip_stall, zip_err;

        wire    dwb_we, dwb_stb, dwb_cyc, dwb_ack, dwb_stall, dwb_err;

        wire    [(BAW-1):0]      dwb_addr;

        wire    [31:0]           dwb_odata;

        // wire [31:0]  zip_debug;

//

// We'll define our RESET_ADDRESS to be halfway through our flash memory.

//      `define CMOD_ZIPCPU_RESET_ADDRESS       23'h600000

//

// Ahm, No.  We can actually do much better than that.  Our toplevel *.bit file

// only takes up only 335kB.  Let's give it some room to grow to 1024 kB.  Then

// 23 can start our ROM at 23'h400100

//

// Not so fast.  In hindsight, we really want to be  able to adjust the load and

// the program separately.  So, instead, let's place our RESET address at the

// second flash erase block.  That way, we can change our program code found

// in the flash without needing to change our FPGA load and vice versa.

//

// 23'h404000

        wire    cpu_reset, tmrb_int;

`ifdef  INCLUDE_CPU_RESET_LOGIC

        reg     btn_reset, x_button, r_button;

        initial btn_reset = 1'b0;

        initial x_button = 1'b0;

        initial r_button = 1'b0;

        always @(posedge i_clk)

        begin

                x_button <= i_btn[1];

                r_button <= x_button;

`ifdef  SECOND_TIMER_IS_WATCHDOG

                btn_reset <= ((r_button)&&(zip_cpu_int))||(tmrb_int);

`else

                btn_reset <= ((r_button)&&(zip_cpu_int));

`endif

        end

        assign  cpu_reset = btn_reset;

`else

        assign  cpu_reset = 1'b0;

`endif

        zipbones #(CMOD_ZIPCPU_RESET_ADDRESS,ZA,6)

                thecpu(i_clk, btn_reset, // 1'b0,

                        // Zippys wishbone interface

                        wb_cyc, wb_stb, wb_we, w_zip_addr, wb_data,

                                wb_ack, wb_stall, wb_idata, wb_err,

                        w_interrupt, zip_cpu_int,

                        // Debug wishbone interface -- not really used

                        1'b0, 1'b0,1'b0, 1'b0, 32'h00,

                                zip_dbg_ack, zip_dbg_stall, zip_dbg_data,

                        zip_scope_data);

        generate

        if (ZA < BAW)

                assign  wb_addr = { {(BAW-ZA){1'b0}}, w_zip_addr };

        else

                assign  wb_addr = w_zip_addr;

        endgenerate

        wire    io_sel, flash_sel, flctl_sel, scop_sel, cfg_sel, mem_sel,

                        rtc_sel, none_sel, many_sel;

        wire    flash_ack, scop_ack, cfg_ack, mem_ack, many_ack;

        wire    rtc_ack, rtc_stall;

`ifdef  INCLUDE_RTC

        assign  rtc_stall = 1'b0;

`endif

        wire    io_stall, flash_stall, scop_stall, cfg_stall, mem_stall;

        reg     io_ack;

        wire    [31:0]   flash_data, scop_data, cfg_data, mem_data, pwm_data,

                        spio_data, gpio_data, uart_data;

        reg     [31:0]   io_data;

        reg     [(BAW-1):0]      bus_err_addr;

        assign  wb_ack = (wb_cyc)&&((io_ack)||(scop_ack)||(cfg_ack)

`ifdef  INCLUDE_RTC

                                ||(rtc_ack)

`endif

                                ||(mem_ack)||(flash_ack)||((none_sel)&&(1'b1)));

        assign  wb_stall = ((io_sel)&&(io_stall))

                        ||((scop_sel)&&(scop_stall))

                        ||((cfg_sel)&&(cfg_stall))

                        ||((mem_sel)&&(mem_stall))

`ifdef  INCLUDE_RTC

                        ||((rtc_sel)&&(rtc_stall))

`endif

                        ||((flash_sel||flctl_sel)&&(flash_stall));

                        // (none_sel)&&(1'b0)

        /*

        assign  wb_idata = (io_ack)?io_data

                        : ((scop_ack)?scop_data

                        : ((cfg_ack)?cfg_data

                        : ((mem_ack)?mem_data

                        : ((flash_ack)?flash_data

                        : 32'h00))));

        */

        assign  wb_idata =  (io_ack|scop_ack)?((io_ack )? io_data  : scop_data)

                        : ((mem_ack|rtc_ack)?((mem_ack)?mem_data:rtc_data)

                        : ((cfg_ack) ? cfg_data : flash_data));//if (flash_ack)

        assign  wb_err = ((wb_cyc)&&(wb_stb)&&(none_sel || many_sel)) || many_ack;

        // Addresses ...

        //      0000 xxxx       configuration/control registers

        //      1 xxxx xxxx xxxx xxxx xxxx      Up-sampler taps

        assign  io_sel   =((wb_cyc)&&(io_addr[5:0]==6'h1));

        assign  scop_sel =((wb_cyc)&&(io_addr[5:1]==5'h1));

        assign  flctl_sel= 1'b0; // ((wb_cyc)&&(io_addr[5:1]==5'h1));

        assign  cfg_sel  =((wb_cyc)&&(io_addr[5:2]==4'h1));

        // zip_sel is not on the bus at this point

`ifdef  INCLUDE_RTC

        assign  rtc_sel  =((wb_cyc)&&(io_addr[5:3]==3'h1));

`endif

        assign  mem_sel  =((wb_cyc)&&(io_addr[5:4]==2'h1));

        assign  flash_sel=((wb_cyc)&&(io_addr[5]));

`ifdef  FULL_BUSERR_CALCULATION

        assign  none_sel =((wb_cyc)&&(wb_stb)&&

                        ((io_addr==6'h0)

                        ||((~io_addr[5])&&(|wb_addr[22:14]))

                        ||((io_addr[5:4]==2'b00)&&(|wb_addr[12])))

                        );

        assign  many_sel =((wb_cyc)&&(wb_stb)&&(

                         {3'h0, io_sel}

                        +{3'h0, flctl_sel}

                        +{3'h0, scop_sel}

                        +{3'h0, cfg_sel}

                        +{3'h0, rtc_sel}

                        +{3'h0, mem_sel}

                        +{3'h0, flash_sel} > 1));

        assign  many_ack =((wb_cyc)&&(

                         {3'h0, io_ack}

                        +{3'h0, scop_ack}

                        +{3'h0, cfg_ack}

`ifdef  INCLUDE_RTC

                        +{3'h0, rtc_ack}

`endif

                        +{3'h0, mem_ack}

                        +{3'h0, flash_ack} > 1));

`else

        assign  many_ack = 1'b0;

        assign  many_sel = 1'b0;

        assign  none_sel =((wb_cyc)&&(wb_stb)&&(io_addr==6'h0));

`endif

        wire            flash_interrupt, scop_interrupt, tmra_int,

                        rtc_interrupt, gpio_int, pwm_int, keypad_int,button_int;

        //

        //

        //

        reg             rx_rdy;

        wire    [10:0]   int_vector;

        assign  int_vector = {

                                        gpio_int, pwm_int, keypad_int,

                                (~o_tx_stb), rx_rdy,

`ifdef  SECOND_TIMER_IS_WATCHDOG

                                1'b0,

`else

                                tmrb_int,

`endif

                                tmra_int,

                                rtc_interrupt, scop_interrupt,

                                wb_err, button_int };

        wire    [31:0]   pic_data;

        icontrol #(11)  pic(i_clk, 1'b0, (wb_stb)&&(io_sel)

                                        &&(wb_addr[3:0]==4'h0)&&(wb_we),

                        wb_data, pic_data, int_vector, w_interrupt);

        initial bus_err_addr = 0; // `DATESTAMP;

        always @(posedge i_clk)

                if (wb_err)

                        bus_err_addr <= wb_addr;

        wire    [31:0]   timer_a, timer_b;

        wire            zta_ack, zta_stall, ztb_ack, ztb_stall;

        ziptimer        #(32,31,1)

                zipt_a(i_clk, 1'b0, 1'b1, wb_cyc,

`ifdef  INCLUDE_SECOND_TIMER

                                (wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h2),

`else

                                (wb_stb)&&(io_sel)&&(wb_addr[3:1]==3'h1),

`endif

                                wb_we, wb_data, zta_ack, zta_stall, timer_a,

                                tmra_int);

`ifdef  INCLUDE_SECOND_TIMER

`ifdef  SECOND_TIMER_IS_WATCHDOG

        ziptimer        #(32,31,0)

                zipt_b(i_clk, cpu_reset, 1'b1, wb_cyc,

                                (wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h3),

                                wb_we, wb_data, ztb_ack, ztb_stall, timer_b,

                                tmrb_int);

`else

        ziptimer        #(32,31,1)

                zipt_b(i_clk, cpu_reset, 1'b1, wb_cyc,

                                (wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h3),

                                wb_we, wb_data, ztb_ack, ztb_stall, timer_b,

                                tmrb_int);

`endif

`else

        // assign       timer_b = 32'h000;

        assign  timer_b = timer_a;

        assign  tmrb_int = 1'b0;

`endif

        wire    [31:0]   rtc_data;

`ifdef  INCLUDE_RTC

        wire    rtcd_ack, rtcd_stall, ppd;

        // rtcdate      thedate(i_clk, ppd, wb_cyc, (wb_stb)&&(io_sel), wb_we,

                        // wb_data, rtcd_ack, rtcd_stall, date_data);

        reg     r_rtc_ack;

        initial r_rtc_ack = 1'b0;

        always @(posedge i_clk)

                r_rtc_ack <= ((wb_stb)&&(rtc_sel));

        assign  rtc_ack = r_rtc_ack;

        rtclight

                #(23'h35afe5,23,0,0)      // 80 MHz clock

                thetime(i_clk, wb_cyc,

                        ((wb_stb)&&(rtc_sel)), wb_we,

                        { 1'b0, wb_addr[1:0] }, wb_data, rtc_data,

                        rtc_interrupt, ppd);

`else

        assign  rtc_interrupt = 1'b0;

        assign  rtc_data = 32'h00;

        assign  rtc_ack  = 1'b0;

`endif

        always @(posedge i_clk)

                case(wb_addr[3:0])

                        4'h0: io_data <= pic_data;

                        4'h1: io_data <= { {(32-BAW){1'b0}}, bus_err_addr };

                        4'h2: io_data <= timer_a;

                        4'h3: io_data <= timer_b;

                        4'h4: io_data <= pwm_data;

                        4'h5: io_data <= spio_data;

                        4'h6: io_data <= gpio_data;

                        4'h7: io_data <= uart_data;

                        default: io_data <= `DATESTAMP;

                        // 4'h8: io_data <= `DATESTAMP;

                endcase

        always @(posedge i_clk)

                io_ack <= (wb_cyc)&&(wb_stb)&&(io_sel);

        assign  io_stall = 1'b0;

        wire    pwm_ack, pwm_stall;

        wbpwmaudio      #(14'd10000,2,0,14)

                theaudio(i_clk, wb_cyc,

                                ((wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h4)),

                                        wb_we, 1'b0, wb_data,

                                pwm_ack, pwm_stall, pwm_data, o_pwm,

                                        o_pwm_aux, //={pwm_shutdown_n,pwm_gain}

                                        pwm_int);

        //

        // Special Purpose I/O: Keypad, button, LED status and control

        //

        wire    [3:0]    w_led;

        spio    thespio(i_clk, wb_cyc,(wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h5),wb_we,

                        wb_data, spio_data, o_kp_col, i_kp_row, i_btn, w_led,

                        keypad_int, button_int);

        assign  o_led = { w_led[3]|w_interrupt,w_led[2]|zip_cpu_int,w_led[1:0] };

        //

        // General purpose (sort of) I/O:  (Bottom two bits robbed in each

        // direction for an I2C link at the toplevel.v design)

        //

        wbgpio  #(16,16,16'hffff) thegpio(i_clk, wb_cyc,

                        (wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h6), wb_we,

                        wb_data, gpio_data, i_gpio, o_gpio, gpio_int);

        //

        //

        //      Rudimentary serial port control

        //

        reg     [7:0]    r_rx_data;

        // Baud rate is set by clock rate / baud rate.

        // Thus, 80MHz / 115200MBau

        //      = 694.4, or about 0x2b6. 

        // although the CPU might struggle to keep up at this speed without a

        // hardware buffer.

        //

        // We'll add the flag for two stop bits.

        // assign       o_uart_setup = 30'h080002b6; // 115200 MBaud @ an 80MHz clock

        assign  o_uart_setup = 30'h0000208d; // 9600 MBaud, 8N1

        initial o_tx_stb = 1'b0;

        initial o_tx_data = 8'h00;

        always @(posedge i_clk)

                if ((wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h7)&&(wb_we))

                begin

                        o_tx_data <= wb_data[7:0];

                        o_tx_stb <= 1'b1;

                end

                else if ((o_tx_stb)&&(~i_tx_busy))

                        o_tx_stb <= 1'b0;

        initial rx_rdy = 1'b0;

        always @(posedge i_clk)

                if (i_rx_stb)

                        r_rx_data <= i_rx_data;

        always @(posedge i_clk)

        begin

                if((wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h7)&&(~wb_we))

                        rx_rdy <= i_rx_stb;

                else if (i_rx_stb)

                        rx_rdy <= (rx_rdy | i_rx_stb);

        end

        assign  o_uart_cts = (~rx_rdy);

        assign  uart_data = { 23'h0, ~rx_rdy, r_rx_data };

        //

        // uart_ack gets returned as part of io_ack, since that happens when

        // io_sel and wb_stb are defined

        //

        // always @(posedge i_clk)

                // uart_ack<= ((wb_stb)&&(io_sel)&&(wb_addr[3:0]==4'h7));

        //

        //      FLASH MEMORY CONFIGURATION ACCESS

        //

        wbqspiflash #(24)       flashmem(i_clk,

                wb_cyc,(wb_stb)&&(flash_sel),(wb_stb)&&(flctl_sel),wb_we,

                        wb_addr[(24-3):0], wb_data,

                flash_ack, flash_stall, flash_data,

                o_qspi_sck, o_qspi_cs_n, o_qspi_mod, o_qspi_dat, i_qspi_dat,

                flash_interrupt);

        //

        //      MULTIBOOT/ICAPE2 CONFIGURATION ACCESS

        //

        wire    [31:0]   cfg_scope;

`ifdef  FANCY_ICAP_ACCESS

        wbicape6        fpga_cfg(i_clk, wb_cyc,(cfg_sel)&&(wb_stb), wb_we,

                                wb_addr[5:0], wb_data,

                                cfg_ack, cfg_stall, cfg_data,

                                cfg_scope);

`else

        reg     r_cfg_ack;

        always @(posedge i_clk)

                r_cfg_ack <= (wb_cyc)&&(cfg_sel)&&(wb_stb);

        assign  cfg_ack   = r_cfg_ack;

        assign  cfg_stall = 1'b0;

        assign  cfg_data  = 32'h00;

        assign  cfg_scope = 32'h00;

`endif

        //

        //      ON-CHIP RAM MEMORY ACCESS

        //

`ifdef  IMPLEMENT_ONCHIP_RAM

        memdev  #(12) ram(i_clk, wb_cyc, (wb_stb)&&(mem_sel), wb_we,

                        wb_addr[11:0], wb_data, mem_ack, mem_stall, mem_data);

`else

        assign  mem_data = 32'h00;

        assign  mem_stall = 1'b0;

        reg     r_mem_ack;

        always @(posedge i_clk)

                r_mem_ack <= (wb_cyc)&&(wb_stb)&&(mem_sel);

        assign  mem_ack = r_mem_ack;

`endif

        //

        //

        //      WISHBONE SCOPE

        //

        //

        //

        //

        wire    [31:0]   scop_cfg_data;

        wire            scop_cfg_ack, scop_cfg_stall, scop_cfg_interrupt;

`ifdef  DBG_SCOPE

        wire            scop_cfg_trigger;

        assign  scop_cfg_trigger = (wb_cyc)&&(wb_stb)&&(cfg_sel);

        // wire scop_trigger = scop_cfg_trigger;

        wire    scop_trigger = (zip_cpu_int) || (cpu_reset);

`ifdef  COMPRESSED_SCOPE

        wbscopc #(5'ha)

`else

        wbscope #(5'ha)

`endif

        wbcfgscope(i_clk, 1'b1, scop_trigger,

`ifdef  COMPRESSED_SCOPE

                // cfg_scope[30:0],

                zip_scope_data[30:0],

`else

                // cfg_scope[31:0],

                zip_scope_data[31:0],

`endif

                // Wishbone interface

                i_clk, wb_cyc, (wb_stb)&&(scop_sel),

                                wb_we, wb_addr[0], wb_data,

                        scop_cfg_ack, scop_cfg_stall, scop_cfg_data,

                scop_cfg_interrupt);

`else

        reg     r_scop_cfg_ack;

        always @(posedge i_clk)

                r_scop_cfg_ack <= (wb_cyc)&&(wb_stb)&&(scop_sel);

        assign  scop_cfg_ack = r_scop_cfg_ack;

        assign  scop_cfg_data = 32'h000;

        assign  scop_cfg_stall= 1'b0;

`endif

        assign  scop_interrupt = scop_cfg_interrupt;

        assign  scop_ack   = scop_cfg_ack;

        assign  scop_stall = scop_cfg_stall;

        assign  scop_data  = scop_cfg_data;

endmodule