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[/] [s6soc/] [trunk/] [rtl/] [llqspi.v] - Rev 46
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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 Technology, 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; // output wire [22:0] o_dbg; // assign o_dbg = { state, spi_len, // o_busy, o_valid, o_cs_n, o_sck, o_mod, o_dat, 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; initial o_mod = `QSPI_MOD_SPI; 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; r_word <= i_word; r_spd <= i_spd; r_dir <= i_dir; if (i_wr) begin state <= `QSPI_START; spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8; o_cs_n <= 1'b0; // o_sck <= 1'b1; o_busy <= 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) o_dat <= r_word[31:28]; else o_dat <= { 3'b110, r_word[31] }; 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 r_spd <= i_spd; r_dir <= i_dir; if (i_spd) begin r_word <= { i_word[27:0], 4'h0 }; spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8 - 6'h4; end else begin r_word <= { i_word[30:0], 1'b0 }; spi_len<= { 1'b0, i_len, 3'b000 } + 6'h8 - 6'h1; end 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 // Set up the first bits on the bus o_mod <= (i_spd) ? { 1'b1, i_dir } : `QSPI_MOD_SPI; if (i_spd) o_dat <= i_word[31:28]; else o_dat <= { 3'b110, i_word[31] }; end else begin o_sck <= 1'b1; state <= (i_hold)?`QSPI_HOLDING : `QSPI_STOP; o_busy <= (~i_hold); 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 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; r_spd <= i_spd; r_dir <= i_dir; if (i_spd) begin r_word <= { i_word[27:0], 4'h0 }; spi_len<= { 1'b0, i_len, 3'b100 }; end else begin r_word <= { i_word[30:0], 1'b0 }; spi_len<= { 1'b0, i_len, 3'b111 }; end 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 // Set up the first bits on the bus o_mod<=(i_spd)?{ 1'b1, i_dir } : `QSPI_MOD_SPI; if (i_spd) o_dat <= i_word[31:28]; else o_dat <= { 3'b110, i_word[31] }; 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