Merge FPGA repository back into UHD repository

The FPGA codebase was removed from the UHD repository in 2014 to reduce
the size of the repository. However, over the last half-decade, the
split between the repositories has proven more burdensome than it has
been helpful. By merging the FPGA code back, it will be possible to
create atomic commits that touch both FPGA and UHD codebases. Continuous
integration testing is also simplified by merging the repositories,
because it was previously difficult to automatically derive the correct
UHD branch when testing a feature branch on the FPGA repository.

This commit also updates the license files and paths therein.

We are therefore merging the repositories again. Future development for
FPGA code will happen in the same repository as the UHD host code and
MPM code.

== Original Codebase and Rebasing ==

The original FPGA repository will be hosted for the foreseeable future
at its original local location: https://github.com/EttusResearch/fpga/

It can be used for bisecting, reference, and a more detailed history.

The final commit from said repository to be merged here is
05003794e2da61cabf64dd278c45685a7abad7ec. This commit is tagged as
v4.0.0.0-pre-uhd-merge.

If you have changes in the FPGA repository that you want to rebase onto
the UHD repository, simply run the following commands:

- Create a directory to store patches (this should be an empty
  directory):

    mkdir ~/patches

- Now make sure that your FPGA codebase is based on the same state as
  the code that was merged:

    cd src/fpga # Or wherever your FPGA code is stored
    git rebase v4.0.0.0-pre-uhd-merge

  Note: The rebase command may look slightly different depending on what
  exactly you're trying to rebase.

- Create a patch set for your changes versus v4.0.0.0-pre-uhd-merge:

    git format-patch v4.0.0.0-pre-uhd-merge -o ~/patches

  Note: Make sure that only patches are stored in your output directory.
  It should otherwise be empty. Make sure that you picked the correct
  range of commits, and only commits you wanted to rebase were exported
  as patch files.

- Go to the UHD repository and apply the patches:

    cd src/uhd # Or wherever your UHD repository is stored
    git am --directory fpga ~/patches/*
    rm -rf ~/patches # This is for cleanup

== Contributors ==

The following people have contributed mainly to these files (this list
is not complete):

Co-authored-by: Alex Williams <alex.williams@ni.com>
Co-authored-by: Andrej Rode <andrej.rode@ettus.com>
Co-authored-by: Ashish Chaudhari <ashish@ettus.com>
Co-authored-by: Ben Hilburn <ben.hilburn@ettus.com>
Co-authored-by: Ciro Nishiguchi <ciro.nishiguchi@ni.com>
Co-authored-by: Daniel Jepson <daniel.jepson@ni.com>
Co-authored-by: Derek Kozel <derek.kozel@ettus.com>
Co-authored-by: EJ Kreinar <ej@he360.com>
Co-authored-by: Humberto Jimenez <humberto.jimenez@ni.com>
Co-authored-by: Ian Buckley <ian.buckley@gmail.com>
Co-authored-by: Jörg Hofrichter <joerg.hofrichter@ni.com>
Co-authored-by: Jon Kiser <jon.kiser@ni.com>
Co-authored-by: Josh Blum <josh@joshknows.com>
Co-authored-by: Jonathon Pendlum <jonathan.pendlum@ettus.com>
Co-authored-by: Martin Braun <martin.braun@ettus.com>
Co-authored-by: Matt Ettus <matt@ettus.com>
Co-authored-by: Michael West <michael.west@ettus.com>
Co-authored-by: Moritz Fischer <moritz.fischer@ettus.com>
Co-authored-by: Nick Foster <nick@ettus.com>
Co-authored-by: Nicolas Cuervo <nicolas.cuervo@ettus.com>
Co-authored-by: Paul Butler <paul.butler@ni.com>
Co-authored-by: Paul David <paul.david@ettus.com>
Co-authored-by: Ryan Marlow <ryan.marlow@ettus.com>
Co-authored-by: Sugandha Gupta <sugandha.gupta@ettus.com>
Co-authored-by: Sylvain Munaut <tnt@246tNt.com>
Co-authored-by: Trung Tran <trung.tran@ettus.com>
Co-authored-by: Vidush Vishwanath <vidush.vishwanath@ettus.com>
Co-authored-by: Wade Fife <wade.fife@ettus.com>

1 files changed, 184 insertions, 0 deletions

diff --git a/fpga/usrp3/lib/wb_spi/rtl/verilog/spi_top16.v b/fpga/usrp3/lib/wb_spi/rtl/verilog/spi_top16.v
new file mode 100644
index 000000000..1dc7d4c39
--- /dev/null
+++ b/fpga/usrp3/lib/wb_spi/rtl/verilog/spi_top16.v
@@ -0,0 +1,184 @@
+
+// Modified 2010 by Matt Ettus to remove old verilog style and
+// allow 16-bit operation
+
+//////////////////////////////////////////////////////////////////////
+////                                                              ////
+////  spi_top.v                                                   ////
+////                                                              ////
+////  This file is part of the SPI IP core project                ////
+////  http://www.opencores.org/projects/spi/                      ////
+////                                                              ////
+////  Author(s):                                                  ////
+////      - Simon Srot (simons@opencores.org)                     ////
+////                                                              ////
+////  All additional information is avaliable in the Readme.txt   ////
+////  file.                                                       ////
+////                                                              ////
+//////////////////////////////////////////////////////////////////////
+////                                                              ////
+//// Copyright (C) 2002 Authors                                   ////
+////
+//// SPDX-License-Identifier: LGPL-3.0-or-later
+////                                                              ////
+//// This source file may be used and distributed without         ////
+//// restriction provided that this copyright statement is not    ////
+//// removed from the file and that any derivative work contains  ////
+//// the original copyright notice and the associated disclaimer. ////
+////                                                              ////
+//// This source file is free software; you can redistribute it   ////
+//// and/or modify it under the terms of the GNU Lesser General   ////
+//// Public License as published by the Free Software Foundation; ////
+//// either version 2.1 of the License, or (at your option) any   ////
+//// later version.                                               ////
+////                                                              ////
+//// This source is distributed in the hope that it will be       ////
+//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////
+//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////
+//// PURPOSE.  See the GNU Lesser General Public License for more ////
+//// details.                                                     ////
+////                                                              ////
+//// You should have received a copy of the GNU Lesser General    ////
+//// Public License along with this source; if not, download it   ////
+//// from http://www.opencores.org/lgpl.shtml                     ////
+////                                                              ////
+//////////////////////////////////////////////////////////////////////
+
+
+`include "spi_defines.v"
+
+module spi_top16
+  (input wb_clk_i, input wb_rst_i, 
+   input [4:0] wb_adr_i, 
+   input [15:0] wb_dat_i, 
+   output reg [15:0] wb_dat_o, 
+   input [1:0] wb_sel_i,
+   input wb_we_i, input wb_stb_i, input wb_cyc_i, 
+   output reg wb_ack_o, output wb_err_o, output reg wb_int_o,
+   
+   // SPI signals
+   output [15:0] ss_pad_o, output sclk_pad_o, output mosi_pad_o, input miso_pad_i);
+   
+   // Internal signals
+   reg [15:0] divider;          // Divider register
+   reg [`SPI_CTRL_BIT_NB-1:0] ctrl;             // Control and status register
+   reg [15:0] 		      ss;               // Slave select register
+   reg [31:0] 		      wb_dat;           // wb data out
+   wire [31:0] 		      rx;               // Rx register
+   wire 		      rx_negedge;       // miso is sampled on negative edge
+   wire 		      tx_negedge;       // mosi is driven on negative edge
+   wire [`SPI_CHAR_LEN_BITS-1:0] char_len;         // char len
+   wire 			 go;               // go
+   wire 			 lsb;              // lsb first on line
+   wire 			 ie;               // interrupt enable
+   wire 			 ass;              // automatic slave select
+   wire 			 spi_divider_sel;  // divider register select
+   wire 			 spi_ctrl_sel;     // ctrl register select
+   wire [3:0] 			 spi_tx_sel;       // tx_l register select
+   wire 			 spi_ss_sel;       // ss register select
+   wire 			 tip;              // transfer in progress
+   wire 			 pos_edge;         // recognize posedge of sclk
+   wire 			 neg_edge;         // recognize negedge of sclk
+   wire 			 last_bit;         // marks last character bit
+   
+   // Address decoder
+   assign spi_divider_sel = wb_cyc_i & wb_stb_i & (wb_adr_i[4:2] == `SPI_DIVIDE);
+   assign spi_ctrl_sel    = wb_cyc_i & wb_stb_i & (wb_adr_i[4:2] == `SPI_CTRL);
+   assign spi_tx_sel[0]   = wb_cyc_i & wb_stb_i & (wb_adr_i[4:2] == `SPI_TX_0);
+   assign spi_tx_sel[1]   = wb_cyc_i & wb_stb_i & (wb_adr_i[4:2] == `SPI_TX_1);
+   assign spi_tx_sel[2]   = wb_cyc_i & wb_stb_i & (wb_adr_i[4:2] == `SPI_TX_2);
+   assign spi_tx_sel[3]   = wb_cyc_i & wb_stb_i & (wb_adr_i[4:2] == `SPI_TX_3);
+   assign spi_ss_sel      = wb_cyc_i & wb_stb_i & (wb_adr_i[4:2] == `SPI_SS);
+   
+   always @(wb_adr_i or rx or ctrl or divider or ss)
+     case (wb_adr_i[4:2])   
+       `SPI_RX_0:    wb_dat = rx[31:0];
+       `SPI_CTRL:    wb_dat = {{32-`SPI_CTRL_BIT_NB{1'b0}}, ctrl};
+       `SPI_DIVIDE:  wb_dat = {16'b0, divider};
+       `SPI_SS:      wb_dat = {16'b0, ss};
+       default : wb_dat = 32'd0;
+     endcase // case (wb_adr_i[4:2])
+   
+   always @(posedge wb_clk_i)
+     if (wb_rst_i)
+       wb_dat_o <= 32'b0;
+     else
+       wb_dat_o <= wb_adr_i[1] ? wb_dat[31:16] : wb_dat[15:0];
+   
+   always @(posedge wb_clk_i)
+     if (wb_rst_i)
+       wb_ack_o <= 1'b0;
+     else
+       wb_ack_o <= wb_cyc_i & wb_stb_i & ~wb_ack_o;
+   
+   assign wb_err_o = 1'b0;
+   
+   // Interrupt
+   always @(posedge wb_clk_i)
+     if (wb_rst_i)
+       wb_int_o <= 1'b0;
+     else if (ie && tip && last_bit && pos_edge)
+       wb_int_o <= 1'b1;
+     else if (wb_ack_o)
+       wb_int_o <= 1'b0;
+   
+   // Divider register
+   always @(posedge wb_clk_i)
+     if (wb_rst_i)
+       divider <= 16'b0;
+     else if (spi_divider_sel && wb_we_i && !tip && ~wb_adr_i[1])
+       divider <= wb_dat_i;
+   
+   // Ctrl register
+   always @(posedge wb_clk_i)
+     if (wb_rst_i)
+       ctrl <= {`SPI_CTRL_BIT_NB{1'b0}};
+     else if(spi_ctrl_sel && wb_we_i && !tip && ~wb_adr_i[1])
+       begin
+          if (wb_sel_i[0])
+            ctrl[7:0] <= wb_dat_i[7:0] | {7'b0, ctrl[0]};
+          if (wb_sel_i[1])
+            ctrl[`SPI_CTRL_BIT_NB-1:8] <= wb_dat_i[`SPI_CTRL_BIT_NB-1:8];
+       end
+     else if(tip && last_bit && pos_edge)
+       ctrl[`SPI_CTRL_GO] <= 1'b0;
+   
+   assign rx_negedge = ctrl[`SPI_CTRL_RX_NEGEDGE];
+   assign tx_negedge = ctrl[`SPI_CTRL_TX_NEGEDGE];
+   assign go         = ctrl[`SPI_CTRL_GO];
+   assign char_len   = ctrl[`SPI_CTRL_CHAR_LEN];
+   assign lsb        = ctrl[`SPI_CTRL_LSB];
+   assign ie         = ctrl[`SPI_CTRL_IE];
+   assign ass        = ctrl[`SPI_CTRL_ASS];
+   
+   // Slave select register
+   always @(posedge wb_clk_i)
+     if (wb_rst_i)
+       ss <= 16'b0;
+     else if(spi_ss_sel && wb_we_i && !tip & ~wb_adr_i[1])
+       begin
+          if (wb_sel_i[0])
+            ss[7:0] <= wb_dat_i[7:0];
+          if (wb_sel_i[1])
+            ss[15:8] <= wb_dat_i[15:8];
+       end
+   
+   assign ss_pad_o = ~((ss & {16{tip & ass}}) | (ss & {16{!ass}}));
+   
+   spi_clgen clgen (.clk_in(wb_clk_i), .rst(wb_rst_i), .go(go), .enable(tip), .last_clk(last_bit),
+                    .divider(divider[`SPI_DIVIDER_LEN-1:0]), .clk_out(sclk_pad_o), .pos_edge(pos_edge), 
+                    .neg_edge(neg_edge));
+
+   wire [3:0] new_sels = { (wb_adr_i[1] & wb_sel_i[1]), (wb_adr_i[1] & wb_sel_i[0]), 
+			   (~wb_adr_i[1] & wb_sel_i[1]), (~wb_adr_i[1] & wb_sel_i[0]) };
+   
+   
+   spi_shift shift (.clk(wb_clk_i), .rst(wb_rst_i), .len(char_len[`SPI_CHAR_LEN_BITS-1:0]),
+                    .latch(spi_tx_sel[3:0] & {4{wb_we_i}}), .byte_sel(new_sels), .lsb(lsb), 
+                    .go(go), .pos_edge(pos_edge), .neg_edge(neg_edge), 
+                    .rx_negedge(rx_negedge), .tx_negedge(tx_negedge),
+                    .tip(tip), .last(last_bit), 
+                    .p_in({wb_dat_i,wb_dat_i}), .p_out(rx), 
+                    .s_clk(sclk_pad_o), .s_in(miso_pad_i), .s_out(mosi_pad_o));
+
+endmodule // spi_top16