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/*
* PicoSoC - A simple example SoC using PicoRV32
*
* Copyright (C) 2017 Clifford Wolf <clifford@clifford.at>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
`ifndef PICORV32_REGS
`ifdef PICORV32_V
`error "picosoc.v must be read before picorv32.v!"
`endif
`define PICORV32_REGS picosoc_regs
`endif
module picosoc (
input clk,
input resetn,
output iomem_valid,
input iomem_ready,
output [ 3:0] iomem_wstrb,
output [31:0] iomem_addr,
output [31:0] iomem_wdata,
input [31:0] iomem_rdata,
input irq_5,
input irq_6,
input irq_7,
output ser_tx,
input ser_rx,
output flash_csb,
output flash_clk,
output flash_io0_oe,
output flash_io1_oe,
output flash_io2_oe,
output flash_io3_oe,
output flash_io0_do,
output flash_io1_do,
output flash_io2_do,
output flash_io3_do,
input flash_io0_di,
input flash_io1_di,
input flash_io2_di,
input flash_io3_di
);
parameter integer MEM_WORDS = 256;
parameter [31:0] STACKADDR = (4*MEM_WORDS); // end of memory
parameter [31:0] PROGADDR_RESET = 32'h 0010_0000; // 1 MB into flash
reg [31:0] irq;
wire irq_stall = 0;
wire irq_uart = 0;
always @* begin
irq = 0;
irq[3] = irq_stall;
irq[4] = irq_uart;
irq[5] = irq_5;
irq[6] = irq_6;
irq[7] = irq_7;
end
wire mem_valid;
wire mem_instr;
wire mem_ready;
wire [31:0] mem_addr;
wire [31:0] mem_wdata;
wire [3:0] mem_wstrb;
wire [31:0] mem_rdata;
wire spimem_ready;
wire [31:0] spimem_rdata;
reg ram_ready;
wire [31:0] ram_rdata;
assign iomem_valid = mem_valid && (mem_addr[31:24] > 8'h 01);
assign iomem_wstrb = mem_wstrb;
assign iomem_addr = mem_addr;
assign iomem_wdata = mem_wdata;
wire spimemio_cfgreg_sel = mem_valid && (mem_addr == 32'h 0200_0000);
wire [31:0] spimemio_cfgreg_do;
wire simpleuart_reg_div_sel = mem_valid && (mem_addr == 32'h 0200_0004);
wire [31:0] simpleuart_reg_div_do;
wire simpleuart_reg_dat_sel = mem_valid && (mem_addr == 32'h 0200_0008);
wire [31:0] simpleuart_reg_dat_do;
wire simpleuart_reg_dat_wait;
assign mem_ready = (iomem_valid && iomem_ready) || spimem_ready || ram_ready || spimemio_cfgreg_sel ||
simpleuart_reg_div_sel || (simpleuart_reg_dat_sel && !simpleuart_reg_dat_wait);
assign mem_rdata = (iomem_valid && iomem_ready) ? iomem_rdata : spimem_ready ? spimem_rdata : ram_ready ? ram_rdata :
spimemio_cfgreg_sel ? spimemio_cfgreg_do : simpleuart_reg_div_sel ? simpleuart_reg_div_do :
simpleuart_reg_dat_sel ? simpleuart_reg_dat_do : 32'h 0000_0000;
picorv32 #(
.STACKADDR(STACKADDR),
.PROGADDR_RESET(PROGADDR_RESET),
.PROGADDR_IRQ(32'h 0000_0000),
.BARREL_SHIFTER(1),
.COMPRESSED_ISA(1),
.ENABLE_MUL(1),
.ENABLE_DIV(1),
.ENABLE_IRQ(1),
.ENABLE_IRQ_QREGS(0)
) cpu (
.clk (clk ),
.resetn (resetn ),
.mem_valid (mem_valid ),
.mem_instr (mem_instr ),
.mem_ready (mem_ready ),
.mem_addr (mem_addr ),
.mem_wdata (mem_wdata ),
.mem_wstrb (mem_wstrb ),
.mem_rdata (mem_rdata ),
.irq (irq )
);
spimemio spimemio (
.clk (clk),
.resetn (resetn),
.valid (mem_valid && mem_addr >= 4*MEM_WORDS && mem_addr < 32'h 0200_0000),
.ready (spimem_ready),
.addr (mem_addr[23:0]),
.rdata (spimem_rdata),
.flash_csb (flash_csb ),
.flash_clk (flash_clk ),
.flash_io0_oe (flash_io0_oe),
.flash_io1_oe (flash_io1_oe),
.flash_io2_oe (flash_io2_oe),
.flash_io3_oe (flash_io3_oe),
.flash_io0_do (flash_io0_do),
.flash_io1_do (flash_io1_do),
.flash_io2_do (flash_io2_do),
.flash_io3_do (flash_io3_do),
.flash_io0_di (flash_io0_di),
.flash_io1_di (flash_io1_di),
.flash_io2_di (flash_io2_di),
.flash_io3_di (flash_io3_di),
.cfgreg_we(spimemio_cfgreg_sel ? mem_wstrb : 4'b 0000),
.cfgreg_di(mem_wdata),
.cfgreg_do(spimemio_cfgreg_do)
);
simpleuart simpleuart (
.clk (clk ),
.resetn (resetn ),
.ser_tx (ser_tx ),
.ser_rx (ser_rx ),
.reg_div_we (simpleuart_reg_div_sel ? mem_wstrb : 4'b 0000),
.reg_div_di (mem_wdata),
.reg_div_do (simpleuart_reg_div_do),
.reg_dat_we (simpleuart_reg_dat_sel ? mem_wstrb[0] : 1'b 0),
.reg_dat_re (simpleuart_reg_dat_sel && !mem_wstrb),
.reg_dat_di (mem_wdata),
.reg_dat_do (simpleuart_reg_dat_do),
.reg_dat_wait(simpleuart_reg_dat_wait)
);
always @(posedge clk)
ram_ready <= mem_valid && !mem_ready && mem_addr < 4*MEM_WORDS;
picosoc_mem #(.WORDS(MEM_WORDS)) memory (
.clk(clk),
.wen((mem_valid && !mem_ready && mem_addr < 4*MEM_WORDS) ? mem_wstrb : 4'b0),
.addr(mem_addr[23:2]),
.wdata(mem_wdata),
.rdata(ram_rdata)
);
endmodule
// Implementation note:
// Replace the following two modules with wrappers for your SRAM cells.
module picosoc_regs (
input clk, wen,
input [5:0] waddr,
input [5:0] raddr1,
input [5:0] raddr2,
input [31:0] wdata,
output [31:0] rdata1,
output [31:0] rdata2
);
reg [31:0] regs [0:31];
always @(posedge clk)
if (wen) regs[waddr[4:0]] <= wdata;
assign rdata1 = regs[raddr1[4:0]];
assign rdata2 = regs[raddr2[4:0]];
endmodule
module picosoc_mem #(
parameter integer WORDS = 256
) (
input clk,
input [3:0] wen,
input [21:0] addr,
input [31:0] wdata,
output reg [31:0] rdata
);
reg [31:0] mem [0:WORDS-1];
always @(posedge clk) begin
rdata <= mem[addr];
if (wen[0]) mem[addr][ 7: 0] <= wdata[ 7: 0];
if (wen[1]) mem[addr][15: 8] <= wdata[15: 8];
if (wen[2]) mem[addr][23:16] <= wdata[23:16];
if (wen[3]) mem[addr][31:24] <= wdata[31:24];
end
endmodule
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