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///////////////////////////////////////////////////////////////////////////
//
// Filename:    llqspi.v
//
// Project:     Wishbone Controlled Quad SPI Flash Controller
//
// Purpose:     Reads/writes a word (user selectable number of bytes) of data
//              to/from a Quad SPI port.  The port is understood to be 
//              a normal SPI port unless the driver requests four bit mode.
//              When not in use, unlike our previous SPI work, no bits will
//              toggle.
//
// Creator:     Dan Gisselquist
//              Gisselquist Tecnology, LLC
//
///////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2015, 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
//
//
///////////////////////////////////////////////////////////////////////////
`define QSPI_IDLE       3'h0
`define QSPI_START      3'h1
`define QSPI_BITS       3'h2
`define QSPI_READY      3'h3
`define QSPI_HOLDING    3'h4
`define QSPI_STOP       3'h5
`define QSPI_STOP_B     3'h6
 
// Modes
`define QSPI_MOD_SPI    2'b00
`define QSPI_MOD_QOUT   2'b10
`define QSPI_MOD_QIN    2'b11
 
module  llqspi(i_clk,
                // Module interface
                i_wr, i_hold, i_word, i_len, i_spd, i_dir,
                        o_word, o_valid, o_busy,
                // QSPI interface
                o_sck, o_cs_n, o_mod, o_dat, i_dat);
        input                   i_clk;
        // Chip interface
        //      Can send info
        //              i_dir = 1, i_spd = 0, i_hold = 0, i_wr = 1,
        //                      i_word = { 1'b0, 32'info to send },
        //                      i_len = # of bytes in word-1
        input                   i_wr, i_hold;
        input           [31:0]   i_word;
        input           [1:0]    i_len;  // 0=>8bits, 1=>16 bits, 2=>24 bits, 3=>32 bits
        input                   i_spd; // 0 -> normal QPI, 1 -> QSPI
        input                   i_dir; // 0 -> read, 1 -> write to SPI
        output  reg     [31:0]   o_word;
        output  reg             o_valid, o_busy;
        // Interface with the QSPI lines
        output  reg             o_sck;
        output  reg             o_cs_n;
        output  reg     [1:0]    o_mod;
        output  reg     [3:0]    o_dat;
        input           [3:0]    i_dat;
 
        // Timing:
        //
        //      Tick    Clk     BSY/WR  CS_n    BIT/MO  STATE
        //       0      1       0/0     1        -      
        //       1      1       0/1     1        -
        //       2      1       1/0     0         -      QSPI_START
        //       3      0        1/0     0         -      QSPI_START
        //       4      0        1/0     0         0      QSPI_BITS
        //       5      1       1/0     0         0      QSPI_BITS
        //       6      0        1/0     0         1      QSPI_BITS
        //       7      1       1/0     0         1      QSPI_BITS
        //       8      0        1/0     0         2      QSPI_BITS
        //       9      1       1/0     0         2      QSPI_BITS
        //      10      0        1/0     0         3      QSPI_BITS
        //      11      1       1/0     0         3      QSPI_BITS
        //      12      0        1/0     0         4      QSPI_BITS
        //      13      1       1/0     0         4      QSPI_BITS
        //      14      0        1/0     0         5      QSPI_BITS
        //      15      1       1/0     0         5      QSPI_BITS
        //      16      0        1/0     0         6      QSPI_BITS
        //      17      1       1/1     0         6      QSPI_BITS
        //      18      0        1/1     0         7      QSPI_READY
        //      19      1       0/1     0         7      QSPI_READY
        //      20      0        1/0/V   0         8      QSPI_BITS
        //      21      1       1/0     0         8      QSPI_BITS
        //      22      0        1/0     0         9      QSPI_BITS
        //      23      1       1/0     0         9      QSPI_BITS
        //      24      0        1/0     0        10      QSPI_BITS
        //      25      1       1/0     0        10      QSPI_BITS
        //      26      0        1/0     0        11      QSPI_BITS
        //      27      1       1/0     0        11      QSPI_BITS
        //      28      0        1/0     0        12      QSPI_BITS
        //      29      1       1/0     0        12      QSPI_BITS
        //      30      0        1/0     0        13      QSPI_BITS
        //      31      1       1/0     0        13      QSPI_BITS
        //      32      0        1/0     0        14      QSPI_BITS
        //      33      1       1/0     0        14      QSPI_BITS
        //      34      0        1/0     0        15      QSPI_READY
        //      35      1       1/0     0        15      QSPI_READY
        //      36      1       1/0/V   0         -      QSPI_STOP
        //      37      1       1/0     0         -      QSPI_STOPB
        //      38      1       1/0     1        -      QSPI_IDLE
        //      39      1       0/0     1        -
        // Now, let's switch from single bit to quad mode
        //      40      1       0/0     1        -      QSPI_IDLE
        //      41      1       0/1     1        -      QSPI_IDLE
        //      42      1       1/0     0         -      QSPI_START
        //      43      0        1/0     0         -      QSPI_START
        //      44      0        1/0     0         0      QSPI_BITS
        //      45      1       1/0     0         0      QSPI_BITS
        //      46      0        1/0     0         1      QSPI_BITS
        //      47      1       1/0     0         1      QSPI_BITS
        //      48      0        1/0     0         2      QSPI_BITS
        //      49      1       1/0     0         2      QSPI_BITS
        //      50      0        1/0     0         3      QSPI_BITS
        //      51      1       1/0     0         3      QSPI_BITS
        //      52      0        1/0     0         4      QSPI_BITS
        //      53      1       1/0     0         4      QSPI_BITS
        //      54      0        1/0     0         5      QSPI_BITS
        //      55      1       1/0     0         5      QSPI_BITS
        //      56      0        1/0     0         6      QSPI_BITS
        //      57      1       1/1/QR  0         6      QSPI_BITS
        //      58      0        1/1/QR  0         7      QSPI_READY
        //      59      1       0/1/QR  0         7      QSPI_READY
        //      60      0        1/0/?/V 0         8-11   QSPI_BITS
        //      61      1       1/0/?   0         8-11   QSPI_BITS
        //      62      0        1/0/?   0         12-15  QSPI_BITS
        //      63      1       1/0/?   0         12-15  QSPI_BITS
        //      64      1       1/0/?/V 0        -       QSPI_STOP
        //      65      1       1/0/?   0        -       QSPI_STOPB
        //      66      1       1/0/?   1       -       QSPI_IDLE
        //      67      1       0/0     1       -       QSPI_IDLE
        // Now let's try something entirely in Quad read mode, from the
        // beginning
        //      68      1       0/1/QR  1       -       QSPI_IDLE
        //      69      1       1/0     0        -       QSPI_START
        //      70      0        1/0     0        -       QSPI_START
        //      71      0        1/0     0        0-3     QSPI_BITS
        //      72      1       1/0     0        0-3     QSPI_BITS
        //      73      0        1/1/QR  0        4-7     QSPI_BITS
        //      74      1       0/1/QR  0        4-7     QSPI_BITS
        //      75      0        1/?/?/V 0        8-11    QSPI_BITS
        //      76      1       1/?/?   0        8-11    QSPI_BITS
        //      77      0        1/1/QR  0        12-15   QSPI_BITS
        //      78      1       0/1/QR  0        12-15   QSPI_BITS
        //      79      0        1/?/?/V 0        16-19   QSPI_BITS
        //      80      1       1/0     0        16-19   QSPI_BITS
        //      81      0        1/0     0        20-23   QSPI_BITS
        //      82      1       1/0     0        20-23   QSPI_BITS
        //      83      1       1/0/V   0        -       QSPI_STOP
        //      84      1       1/0     0        -       QSPI_STOPB
        //      85      1       1/0     1       -       QSPI_IDLE
        //      86      1       0/0     1       -       QSPI_IDLE
 
        wire    i_miso;
        assign  i_miso = i_dat[1];
 
        reg             r_spd, r_dir;
        reg     [5:0]    spi_len;
        reg     [31:0]   r_word;
        reg     [30:0]   r_input;
        reg     [2:0]    state;
        initial state = `QSPI_IDLE;
        initial o_sck   = 1'b1;
        initial o_cs_n  = 1'b1;
        initial o_dat   = 4'hd;
        initial o_valid = 1'b0;
        initial o_busy  = 1'b0;
        initial r_input = 31'h000;
        always @(posedge i_clk)
                if ((state == `QSPI_IDLE)&&(o_sck))
                begin
                        o_cs_n <= 1'b1;
                        o_valid <= 1'b0;
                        o_busy  <= 1'b0;
                        o_mod <= `QSPI_MOD_SPI;
                        if (i_wr)
                        begin
                                r_word <= i_word;
                                state <= `QSPI_START;
                                r_spd <= i_spd;
                                r_dir <= i_dir;
                                spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8;
                                o_cs_n <= 1'b0;
                                o_busy <= 1'b1;
                                o_sck <= 1'b1;
                        end
                end else if (state == `QSPI_START)
                begin // We come in here with sck high, stay here 'til sck is low
                        o_sck <= 1'b0;
                        if (o_sck == 1'b0)
                        begin
                                state <= `QSPI_BITS;
                                spi_len<= spi_len - ( (r_spd)? 6'h4 : 6'h1 );
                                if (r_spd)
                                        r_word <= { r_word[27:0], 4'h0 };
                                else
                                        r_word <= { r_word[30:0], 1'b0 };
                        end
                        o_mod <= (r_spd) ? { 1'b1, r_dir } : `QSPI_MOD_SPI;
                        o_cs_n <= 1'b0;
                        o_busy <= 1'b1;
                        o_valid <= 1'b0;
                        if (r_spd)
                        begin
                                o_dat <= r_word[31:28];
                                // r_word <= { r_word[27:0], 4'h0 };
                        end else begin
                                o_dat <= { 3'b110, r_word[31] };
                                // r_word <= { r_word[30:0], 1'b0 };
                        end
                end else if (~o_sck)
                begin
                        o_sck <= 1'b1;
                        o_busy <= ((state != `QSPI_READY)||(~i_wr));
                        o_valid <= 1'b0;
                end else if (state == `QSPI_BITS)
                begin
                        // Should enter into here with at least a spi_len
                        // of one, perhaps more
                        o_sck <= 1'b0;
                        o_busy <= 1'b1;
                        if (r_spd)
                        begin
                                o_dat <= r_word[31:28];
                                r_word <= { r_word[27:0], 4'h0 };
                                spi_len <= spi_len - 6'h4;
                                if (spi_len == 6'h4)
                                        state <= `QSPI_READY;
                        end else begin
                                o_dat <= { 3'b110, r_word[31] };
                                r_word <= { r_word[30:0], 1'b0 };
                                spi_len <= spi_len - 6'h1;
                                if (spi_len == 6'h1)
                                        state <= `QSPI_READY;
                        end
 
                        o_valid <= 1'b0;
                        if (~o_mod[1])
                                r_input <= { r_input[29:0], i_miso };
                        else if (o_mod[1])
                                r_input <= { r_input[26:0], i_dat };
                end else if (state == `QSPI_READY)
                begin
                        o_valid <= 1'b0;
                        o_cs_n <= 1'b0;
                        o_busy <= 1'b1;
                        // This is the state on the last clock (both low and
                        // high clocks) of the data.  Data is valid during
                        // this state.  Here we chose to either STOP or
                        // continue and transmit more.
                        o_sck <= (i_hold); // No clocks while holding
                        if((~o_busy)&&(i_wr))// Acknowledge a new request
                        begin
                                state <= `QSPI_BITS;
                                o_busy <= 1'b1;
                                o_sck <= 1'b0;
 
                                // Read the new request off the bus
                                r_spd <= i_spd;
                                r_dir <= i_dir;
                                // Set up the first bits on the bus
                                o_mod <= (i_spd) ? { 1'b1, i_dir } : `QSPI_MOD_SPI;
                                if (i_spd)
                                begin
                                        o_dat <= i_word[31:28];
                                        r_word <= { i_word[27:0], 4'h0 };
                                        // spi_len <= spi_len - 4;
                                        spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8
                                                - 6'h4;
                                end else begin
                                        o_dat <= { 3'b110, i_word[31] };
                                        r_word <= { i_word[30:0], 1'b0 };
                                        spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8
                                                - 6'h1;
                                end
 
                                // Read a bit upon any transition
                                o_valid <= 1'b1;
                                if (~o_mod[1])
                                begin
                                        r_input <= { r_input[29:0], i_miso };
                                        o_word  <= { r_input[30:0], i_miso };
                                end else if (o_mod[1])
                                begin
                                        r_input <= { r_input[26:0], i_dat };
                                        o_word  <= { r_input[27:0], i_dat };
                                end
                        end else begin
                                o_sck <= 1'b1;
                                state <= (i_hold)?`QSPI_HOLDING : `QSPI_STOP;
                                o_busy <= (~i_hold);
 
                                // Read a bit upon any transition
                                o_valid <= 1'b1;
                                if (~o_mod[1])
                                begin
                                        r_input <= { r_input[29:0], i_miso };
                                        o_word  <= { r_input[30:0], i_miso };
                                end else if (o_mod[1])
                                begin
                                        r_input <= { r_input[26:0], i_dat };
                                        o_word  <= { r_input[27:0], i_dat };
                                end
                        end
                end else if (state == `QSPI_HOLDING)
                begin
                        // We need this state so that the o_valid signal
                        // can get strobed with our last result.  Otherwise
                        // we could just sit in READY waiting for a new command.
                        //
                        // Incidentally, the change producing this state was
                        // the result of a nasty race condition.  See the
                        // commends in wbqspiflash for more details.
                        //
                        o_valid <= 1'b0;
                        o_cs_n <= 1'b0;
                        o_busy <= 1'b0;
                        if((~o_busy)&&(i_wr))// Acknowledge a new request
                        begin
                                state  <= `QSPI_BITS;
                                o_busy <= 1'b1;
                                o_sck  <= 1'b0;
 
                                // Read the new request off the bus
                                r_spd <= i_spd;
                                r_dir <= i_dir;
                                // Set up the first bits on the bus
                                o_mod<=(i_spd)?{ 1'b1, i_dir } : `QSPI_MOD_SPI;
                                if (i_spd)
                                begin
                                        o_dat <= i_word[31:28];
                                        r_word <= { i_word[27:0], 4'h0 };
                                        spi_len<= { 1'b0, i_len, 3'b100 };
                                end else begin
                                        o_dat <= { 3'b110, i_word[31] };
                                        r_word <= { i_word[30:0], 1'b0 };
                                        spi_len<= { 1'b0, i_len, 3'b111 };
                                end
                        end else begin
                                o_sck <= 1'b1;
                                state <= (i_hold)?`QSPI_HOLDING : `QSPI_STOP;
                                o_busy <= (~i_hold);
                        end
                end else if (state == `QSPI_STOP)
                begin
                        o_sck   <= 1'b1; // Stop the clock
                        o_valid <= 1'b0; // Output may have just been valid, but no more
                        o_busy  <= 1'b1; // Still busy till port is clear
                        state <= `QSPI_STOP_B;
                        o_mod <= `QSPI_MOD_SPI;
                end else if (state == `QSPI_STOP_B)
                begin
                        o_cs_n <= 1'b1;
                        o_sck <= 1'b1;
                        // Do I need this????
                        // spi_len <= 3; // Minimum CS high time before next cmd
                        state <= `QSPI_IDLE;
                        o_valid <= 1'b0;
                        o_busy <= 1'b1;
                        o_mod <= `QSPI_MOD_SPI;
                end else begin // Invalid states, should never get here
                        state   <= `QSPI_STOP;
                        o_valid <= 1'b0;
                        o_busy  <= 1'b1;
                        o_cs_n  <= 1'b1;
                        o_sck   <= 1'b1;
                        o_mod   <= `QSPI_MOD_SPI;
                        o_dat   <= 4'hd;
                end
 
endmodule
 

Line No.	Rev	Author	Line
1	3	dgisselq	`///////////////////////////////////////////////////////////////////////////`
2	2	dgisselq	`//`
3			`// Filename: llqspi.v`
4			`//`
5	3	dgisselq	`// Project: Wishbone Controlled Quad SPI Flash Controller`
6	2	dgisselq	`//`
7			`// Purpose: Reads/writes a word (user selectable number of bytes) of data`
8			`// to/from a Quad SPI port. The port is understood to be`
9			`// a normal SPI port unless the driver requests four bit mode.`
10			`// When not in use, unlike our previous SPI work, no bits will`
11			`// toggle.`
12			`//`
13			`// Creator: Dan Gisselquist`
14			`// Gisselquist Tecnology, LLC`
15			`//`
16	3	dgisselq	`///////////////////////////////////////////////////////////////////////////`
17	2	dgisselq	`//`
18	3	dgisselq	`// Copyright (C) 2015, Gisselquist Technology, LLC`
19	2	dgisselq	`//`
20	3	dgisselq	`// This program is free software (firmware): you can redistribute it and/or`
21			`// modify it under the terms of the GNU General Public License as published`
22			`// by the Free Software Foundation, either version 3 of the License, or (at`
23			`// your option) any later version.`
24			`//`
25			`// This program is distributed in the hope that it will be useful, but WITHOUT`
26			`// ANY WARRANTY; without even the implied warranty of MERCHANTIBILITY or`
27			`// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License`
28			`// for more details.`
29			`//`
30			`// You should have received a copy of the GNU General Public License along`
31			`// with this program. (It's in the $(ROOT)/doc directory, run make with no`
32			`// target there if the PDF file isn't present.) If not, see`
33			`// <http://www.gnu.org/licenses/> for a copy.`
34			`//`
35			`// License: GPL, v3, as defined and found on www.gnu.org,`
36			`// http://www.gnu.org/licenses/gpl.html`
37			`//`
38			`//`
39			`///////////////////////////////////////////////////////////////////////////`
40	4	dgisselq	`define QSPI_IDLE 3'h0
41			`define QSPI_START 3'h1
42			`define QSPI_BITS 3'h2
43			`define QSPI_READY 3'h3
44			`define QSPI_HOLDING 3'h4
45			`define QSPI_STOP 3'h5
46			`define QSPI_STOP_B 3'h6
47	2	dgisselq
48			`// Modes`
49			`define QSPI_MOD_SPI 2'b00
50			`define QSPI_MOD_QOUT 2'b10
51			`define QSPI_MOD_QIN 2'b11
52
53			`module llqspi(i_clk,`
54			`// Module interface`
55			`i_wr, i_hold, i_word, i_len, i_spd, i_dir,`
56			`o_word, o_valid, o_busy,`
57			`// QSPI interface`
58	3	dgisselq	`o_sck, o_cs_n, o_mod, o_dat, i_dat);`
59	2	dgisselq	`input i_clk;`
60			`// Chip interface`
61			`// Can send info`
62			`// i_dir = 1, i_spd = 0, i_hold = 0, i_wr = 1,`
63			`// i_word = { 1'b0, 32'info to send },`
64			`// i_len = # of bytes in word-1`
65			`input i_wr, i_hold;`
66			`input [31:0] i_word;`
67			`input [1:0] i_len; // 0=>8bits, 1=>16 bits, 2=>24 bits, 3=>32 bits`
68			`input i_spd; // 0 -> normal QPI, 1 -> QSPI`
69			`input i_dir; // 0 -> read, 1 -> write to SPI`
70			`output reg [31:0] o_word;`
71			`output reg o_valid, o_busy;`
72			`// Interface with the QSPI lines`
73			`output reg o_sck;`
74			`output reg o_cs_n;`
75			`output reg [1:0] o_mod;`
76			`output reg [3:0] o_dat;`
77			`input [3:0] i_dat;`
78
79			`// Timing:`
80			`//`
81			`// Tick Clk BSY/WR CS_n BIT/MO STATE`
82			`// 0 1 0/0 1 -`
83			`// 1 1 0/1 1 -`
84			`// 2 1 1/0 0 - QSPI_START`
85			`// 3 0 1/0 0 - QSPI_START`
86			`// 4 0 1/0 0 0 QSPI_BITS`
87			`// 5 1 1/0 0 0 QSPI_BITS`
88			`// 6 0 1/0 0 1 QSPI_BITS`
89			`// 7 1 1/0 0 1 QSPI_BITS`
90			`// 8 0 1/0 0 2 QSPI_BITS`
91			`// 9 1 1/0 0 2 QSPI_BITS`
92			`// 10 0 1/0 0 3 QSPI_BITS`
93			`// 11 1 1/0 0 3 QSPI_BITS`
94			`// 12 0 1/0 0 4 QSPI_BITS`
95			`// 13 1 1/0 0 4 QSPI_BITS`
96			`// 14 0 1/0 0 5 QSPI_BITS`
97			`// 15 1 1/0 0 5 QSPI_BITS`
98			`// 16 0 1/0 0 6 QSPI_BITS`
99			`// 17 1 1/1 0 6 QSPI_BITS`
100			`// 18 0 1/1 0 7 QSPI_READY`
101			`// 19 1 0/1 0 7 QSPI_READY`
102			`// 20 0 1/0/V 0 8 QSPI_BITS`
103			`// 21 1 1/0 0 8 QSPI_BITS`
104			`// 22 0 1/0 0 9 QSPI_BITS`
105			`// 23 1 1/0 0 9 QSPI_BITS`
106			`// 24 0 1/0 0 10 QSPI_BITS`
107			`// 25 1 1/0 0 10 QSPI_BITS`
108			`// 26 0 1/0 0 11 QSPI_BITS`
109			`// 27 1 1/0 0 11 QSPI_BITS`
110			`// 28 0 1/0 0 12 QSPI_BITS`
111			`// 29 1 1/0 0 12 QSPI_BITS`
112			`// 30 0 1/0 0 13 QSPI_BITS`
113			`// 31 1 1/0 0 13 QSPI_BITS`
114			`// 32 0 1/0 0 14 QSPI_BITS`
115			`// 33 1 1/0 0 14 QSPI_BITS`
116			`// 34 0 1/0 0 15 QSPI_READY`
117			`// 35 1 1/0 0 15 QSPI_READY`
118			`// 36 1 1/0/V 0 - QSPI_STOP`
119			`// 37 1 1/0 0 - QSPI_STOPB`
120			`// 38 1 1/0 1 - QSPI_IDLE`
121			`// 39 1 0/0 1 -`
122			`// Now, let's switch from single bit to quad mode`
123			`// 40 1 0/0 1 - QSPI_IDLE`
124			`// 41 1 0/1 1 - QSPI_IDLE`
125			`// 42 1 1/0 0 - QSPI_START`
126			`// 43 0 1/0 0 - QSPI_START`
127			`// 44 0 1/0 0 0 QSPI_BITS`
128			`// 45 1 1/0 0 0 QSPI_BITS`
129			`// 46 0 1/0 0 1 QSPI_BITS`
130			`// 47 1 1/0 0 1 QSPI_BITS`
131			`// 48 0 1/0 0 2 QSPI_BITS`
132			`// 49 1 1/0 0 2 QSPI_BITS`
133			`// 50 0 1/0 0 3 QSPI_BITS`
134			`// 51 1 1/0 0 3 QSPI_BITS`
135			`// 52 0 1/0 0 4 QSPI_BITS`
136			`// 53 1 1/0 0 4 QSPI_BITS`
137			`// 54 0 1/0 0 5 QSPI_BITS`
138			`// 55 1 1/0 0 5 QSPI_BITS`
139			`// 56 0 1/0 0 6 QSPI_BITS`
140			`// 57 1 1/1/QR 0 6 QSPI_BITS`
141			`// 58 0 1/1/QR 0 7 QSPI_READY`
142			`// 59 1 0/1/QR 0 7 QSPI_READY`
143			`// 60 0 1/0/?/V 0 8-11 QSPI_BITS`
144			`// 61 1 1/0/? 0 8-11 QSPI_BITS`
145			`// 62 0 1/0/? 0 12-15 QSPI_BITS`
146			`// 63 1 1/0/? 0 12-15 QSPI_BITS`
147			`// 64 1 1/0/?/V 0 - QSPI_STOP`
148			`// 65 1 1/0/? 0 - QSPI_STOPB`
149			`// 66 1 1/0/? 1 - QSPI_IDLE`
150			`// 67 1 0/0 1 - QSPI_IDLE`
151			`// Now let's try something entirely in Quad read mode, from the`
152			`// beginning`
153			`// 68 1 0/1/QR 1 - QSPI_IDLE`
154			`// 69 1 1/0 0 - QSPI_START`
155			`// 70 0 1/0 0 - QSPI_START`
156			`// 71 0 1/0 0 0-3 QSPI_BITS`
157			`// 72 1 1/0 0 0-3 QSPI_BITS`
158			`// 73 0 1/1/QR 0 4-7 QSPI_BITS`
159			`// 74 1 0/1/QR 0 4-7 QSPI_BITS`
160			`// 75 0 1/?/?/V 0 8-11 QSPI_BITS`
161			`// 76 1 1/?/? 0 8-11 QSPI_BITS`
162			`// 77 0 1/1/QR 0 12-15 QSPI_BITS`
163			`// 78 1 0/1/QR 0 12-15 QSPI_BITS`
164			`// 79 0 1/?/?/V 0 16-19 QSPI_BITS`
165			`// 80 1 1/0 0 16-19 QSPI_BITS`
166			`// 81 0 1/0 0 20-23 QSPI_BITS`
167			`// 82 1 1/0 0 20-23 QSPI_BITS`
168			`// 83 1 1/0/V 0 - QSPI_STOP`
169			`// 84 1 1/0 0 - QSPI_STOPB`
170			`// 85 1 1/0 1 - QSPI_IDLE`
171			`// 86 1 0/0 1 - QSPI_IDLE`
172
173			`wire i_miso;`
174			`assign i_miso = i_dat[1];`
175
176			`reg r_spd, r_dir;`
177			`reg [5:0] spi_len;`
178			`reg [31:0] r_word;`
179			`reg [30:0] r_input;`
180			`reg [2:0] state;`
181			initial state = `QSPI_IDLE;
182			`initial o_sck = 1'b1;`
183			`initial o_cs_n = 1'b1;`
184			`initial o_dat = 4'hd;`
185			`initial o_valid = 1'b0;`
186			`initial o_busy = 1'b0;`
187			`initial r_input = 31'h000;`
188			`always @(posedge i_clk)`
189			if ((state == `QSPI_IDLE)&&(o_sck))
190			`begin`
191			`o_cs_n <= 1'b1;`
192			`o_valid <= 1'b0;`
193			`o_busy <= 1'b0;`
194			o_mod <= `QSPI_MOD_SPI;
195			`if (i_wr)`
196			`begin`
197			`r_word <= i_word;`
198			state <= `QSPI_START;
199			`r_spd <= i_spd;`
200			`r_dir <= i_dir;`
201			`spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8;`
202			`o_cs_n <= 1'b0;`
203			`o_busy <= 1'b1;`
204			`o_sck <= 1'b1;`
205			`end`
206			end else if (state == `QSPI_START)
207			`begin // We come in here with sck high, stay here 'til sck is low`
208			`o_sck <= 1'b0;`
209			`if (o_sck == 1'b0)`
210			`begin`
211			state <= `QSPI_BITS;
212			`spi_len<= spi_len - ( (r_spd)? 6'h4 : 6'h1 );`
213			`if (r_spd)`
214			`r_word <= { r_word[27:0], 4'h0 };`
215			`else`
216			`r_word <= { r_word[30:0], 1'b0 };`
217			`end`
218			o_mod <= (r_spd) ? { 1'b1, r_dir } : `QSPI_MOD_SPI;
219			`o_cs_n <= 1'b0;`
220			`o_busy <= 1'b1;`
221			`o_valid <= 1'b0;`
222			`if (r_spd)`
223			`begin`
224			`o_dat <= r_word[31:28];`
225			`// r_word <= { r_word[27:0], 4'h0 };`
226			`end else begin`
227			`o_dat <= { 3'b110, r_word[31] };`
228			`// r_word <= { r_word[30:0], 1'b0 };`
229			`end`
230			`end else if (~o_sck)`
231			`begin`
232			`o_sck <= 1'b1;`
233			o_busy <= ((state != `QSPI_READY)\|\|(~i_wr));
234			`o_valid <= 1'b0;`
235			end else if (state == `QSPI_BITS)
236			`begin`
237			`// Should enter into here with at least a spi_len`
238			`// of one, perhaps more`
239			`o_sck <= 1'b0;`
240			`o_busy <= 1'b1;`
241			`if (r_spd)`
242			`begin`
243			`o_dat <= r_word[31:28];`
244			`r_word <= { r_word[27:0], 4'h0 };`
245			`spi_len <= spi_len - 6'h4;`
246			`if (spi_len == 6'h4)`
247			state <= `QSPI_READY;
248			`end else begin`
249			`o_dat <= { 3'b110, r_word[31] };`
250			`r_word <= { r_word[30:0], 1'b0 };`
251			`spi_len <= spi_len - 6'h1;`
252			`if (spi_len == 6'h1)`
253			state <= `QSPI_READY;
254			`end`
255
256			`o_valid <= 1'b0;`
257			`if (~o_mod[1])`
258			`r_input <= { r_input[29:0], i_miso };`
259			`else if (o_mod[1])`
260			`r_input <= { r_input[26:0], i_dat };`
261			end else if (state == `QSPI_READY)
262			`begin`
263			`o_valid <= 1'b0;`
264			`o_cs_n <= 1'b0;`
265			`o_busy <= 1'b1;`
266			`// This is the state on the last clock (both low and`
267			`// high clocks) of the data. Data is valid during`
268			`// this state. Here we chose to either STOP or`
269			`// continue and transmit more.`
270	4	dgisselq	`o_sck <= (i_hold); // No clocks while holding`
271	2	dgisselq	`if((~o_busy)&&(i_wr))// Acknowledge a new request`
272			`begin`
273			state <= `QSPI_BITS;
274			`o_busy <= 1'b1;`
275			`o_sck <= 1'b0;`
276
277			`// Read the new request off the bus`
278			`r_spd <= i_spd;`
279			`r_dir <= i_dir;`
280			`// Set up the first bits on the bus`
281			o_mod <= (i_spd) ? { 1'b1, i_dir } : `QSPI_MOD_SPI;
282			`if (i_spd)`
283			`begin`
284			`o_dat <= i_word[31:28];`
285			`r_word <= { i_word[27:0], 4'h0 };`
286			`// spi_len <= spi_len - 4;`
287			`spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8`
288			`- 6'h4;`
289			`end else begin`
290			`o_dat <= { 3'b110, i_word[31] };`
291			`r_word <= { i_word[30:0], 1'b0 };`
292			`spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8`
293			`- 6'h1;`
294			`end`
295
296			`// Read a bit upon any transition`
297			`o_valid <= 1'b1;`
298			`if (~o_mod[1])`
299			`begin`
300			`r_input <= { r_input[29:0], i_miso };`
301			`o_word <= { r_input[30:0], i_miso };`
302			`end else if (o_mod[1])`
303			`begin`
304			`r_input <= { r_input[26:0], i_dat };`
305			`o_word <= { r_input[27:0], i_dat };`
306			`end`
307			`end else begin`
308			`o_sck <= 1'b1;`
309	4	dgisselq	state <= (i_hold)?`QSPI_HOLDING : `QSPI_STOP;
310			`o_busy <= (~i_hold);`
311	2	dgisselq
312			`// Read a bit upon any transition`
313			`o_valid <= 1'b1;`
314			`if (~o_mod[1])`
315			`begin`
316			`r_input <= { r_input[29:0], i_miso };`
317			`o_word <= { r_input[30:0], i_miso };`
318			`end else if (o_mod[1])`
319			`begin`
320			`r_input <= { r_input[26:0], i_dat };`
321			`o_word <= { r_input[27:0], i_dat };`
322			`end`
323			`end`
324	4	dgisselq	end else if (state == `QSPI_HOLDING)
325			`begin`
326			`// We need this state so that the o_valid signal`
327			`// can get strobed with our last result. Otherwise`
328			`// we could just sit in READY waiting for a new command.`
329			`//`
330			`// Incidentally, the change producing this state was`
331			`// the result of a nasty race condition. See the`
332			`// commends in wbqspiflash for more details.`
333			`//`
334			`o_valid <= 1'b0;`
335			`o_cs_n <= 1'b0;`
336			`o_busy <= 1'b0;`
337			`if((~o_busy)&&(i_wr))// Acknowledge a new request`
338			`begin`
339			state <= `QSPI_BITS;
340			`o_busy <= 1'b1;`
341			`o_sck <= 1'b0;`
342
343			`// Read the new request off the bus`
344			`r_spd <= i_spd;`
345			`r_dir <= i_dir;`
346			`// Set up the first bits on the bus`
347			o_mod<=(i_spd)?{ 1'b1, i_dir } : `QSPI_MOD_SPI;
348			`if (i_spd)`
349			`begin`
350			`o_dat <= i_word[31:28];`
351			`r_word <= { i_word[27:0], 4'h0 };`
352			`spi_len<= { 1'b0, i_len, 3'b100 };`
353			`end else begin`
354			`o_dat <= { 3'b110, i_word[31] };`
355			`r_word <= { i_word[30:0], 1'b0 };`
356			`spi_len<= { 1'b0, i_len, 3'b111 };`
357			`end`
358			`end else begin`
359			`o_sck <= 1'b1;`
360			state <= (i_hold)?`QSPI_HOLDING : `QSPI_STOP;
361			`o_busy <= (~i_hold);`
362			`end`
363	2	dgisselq	end else if (state == `QSPI_STOP)
364			`begin`
365			`o_sck <= 1'b1; // Stop the clock`
366			`o_valid <= 1'b0; // Output may have just been valid, but no more`
367			`o_busy <= 1'b1; // Still busy till port is clear`
368			state <= `QSPI_STOP_B;
369			o_mod <= `QSPI_MOD_SPI;
370			end else if (state == `QSPI_STOP_B)
371			`begin`
372			`o_cs_n <= 1'b1;`
373			`o_sck <= 1'b1;`
374			`// Do I need this????`
375			`// spi_len <= 3; // Minimum CS high time before next cmd`
376			state <= `QSPI_IDLE;
377			`o_valid <= 1'b0;`
378			`o_busy <= 1'b1;`
379			o_mod <= `QSPI_MOD_SPI;
380			`end else begin // Invalid states, should never get here`
381			state <= `QSPI_STOP;
382			`o_valid <= 1'b0;`
383			`o_busy <= 1'b1;`
384			`o_cs_n <= 1'b1;`
385			`o_sck <= 1'b1;`
386			o_mod <= `QSPI_MOD_SPI;
387			`o_dat <= 4'hd;`
388			`end`
389
390			`endmodule`
391

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