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, 538 insertions, 0 deletions

diff --git a/fpga/usrp3/lib/wishbone/i2c_master_bit_ctrl.v b/fpga/usrp3/lib/wishbone/i2c_master_bit_ctrl.v
new file mode 100644
index 000000000..68ec27004
--- /dev/null
+++ b/fpga/usrp3/lib/wishbone/i2c_master_bit_ctrl.v
@@ -0,0 +1,538 @@
+/////////////////////////////////////////////////////////////////////
+////                                                             ////
+////  WISHBONE rev.B2 compliant I2C Master bit-controller        ////
+////                                                             ////
+////                                                             ////
+////  Author: Richard Herveille                                  ////
+////          richard@asics.ws                                   ////
+////          www.asics.ws                                       ////
+////                                                             ////
+////  Downloaded from: http://www.opencores.org/projects/i2c/    ////
+////                                                             ////
+/////////////////////////////////////////////////////////////////////
+////                                                             ////
+//// Copyright (C) 2001 Richard Herveille                        ////
+////                    richard@asics.ws                         ////
+////                                                             ////
+//// 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 SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY     ////
+//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   ////
+//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS   ////
+//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR      ////
+//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,         ////
+//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES    ////
+//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE   ////
+//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR        ////
+//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF  ////
+//// LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT  ////
+//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT  ////
+//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE         ////
+//// POSSIBILITY OF SUCH DAMAGE.                                 ////
+////                                                             ////
+/////////////////////////////////////////////////////////////////////
+
+//  CVS Log
+//
+//  $Id: i2c_master_bit_ctrl.v,v 1.12 2006/09/04 09:08:13 rherveille Exp $
+//
+//  $Date: 2006/09/04 09:08:13 $
+//  $Revision: 1.12 $
+//  $Author: rherveille $
+//  $Locker:  $
+//  $State: Exp $
+//
+// Change History:
+//               $Log: i2c_master_bit_ctrl.v,v $
+//               Revision 1.12  2006/09/04 09:08:13  rherveille
+//               fixed short scl high pulse after clock stretch
+//               fixed slave model not returning correct '(n)ack' signal
+//
+//               Revision 1.11  2004/05/07 11:02:26  rherveille
+//               Fixed a bug where the core would signal an arbitration lost (AL bit set), when another master controls the bus and the other master generates a STOP bit.
+//
+//               Revision 1.10  2003/08/09 07:01:33  rherveille
+//               Fixed a bug in the Arbitration Lost generation caused by delay on the (external) sda line.
+//               Fixed a potential bug in the byte controller's host-acknowledge generation.
+//
+//               Revision 1.9  2003/03/10 14:26:37  rherveille
+//               Fixed cmd_ack generation item (no bug).
+//
+//               Revision 1.8  2003/02/05 00:06:10  rherveille
+//               Fixed a bug where the core would trigger an erroneous 'arbitration lost' interrupt after being reset, when the reset pulse width < 3 clk cycles.
+//
+//               Revision 1.7  2002/12/26 16:05:12  rherveille
+//               Small code simplifications
+//
+//               Revision 1.6  2002/12/26 15:02:32  rherveille
+//               Core is now a Multimaster I2C controller
+//
+//               Revision 1.5  2002/11/30 22:24:40  rherveille
+//               Cleaned up code
+//
+//               Revision 1.4  2002/10/30 18:10:07  rherveille
+//               Fixed some reported minor start/stop generation timing issuess.
+//
+//               Revision 1.3  2002/06/15 07:37:03  rherveille
+//               Fixed a small timing bug in the bit controller.\nAdded verilog simulation environment.
+//
+//               Revision 1.2  2001/11/05 11:59:25  rherveille
+//               Fixed wb_ack_o generation bug.
+//               Fixed bug in the byte_controller statemachine.
+//               Added headers.
+//
+
+//
+/////////////////////////////////////
+// Bit controller section
+/////////////////////////////////////
+//
+// Translate simple commands into SCL/SDA transitions
+// Each command has 5 states, A/B/C/D/idle
+//
+// start:	SCL	~~~~~~~~~~\____
+//	SDA	~~~~~~~~\______
+//		 x | A | B | C | D | i
+//
+// repstart	SCL	____/~~~~\___
+//	SDA	__/~~~\______
+//		 x | A | B | C | D | i
+//
+// stop	SCL	____/~~~~~~~~
+//	SDA	==\____/~~~~~
+//		 x | A | B | C | D | i
+//
+//- write	SCL	____/~~~~\____
+//	SDA	==X=========X=
+//		 x | A | B | C | D | i
+//
+//- read	SCL	____/~~~~\____
+//	SDA	XXXX=====XXXX
+//		 x | A | B | C | D | i
+//
+
+// Timing:     Normal mode      Fast mode
+///////////////////////////////////////////////////////////////////////
+// Fscl        100KHz           400KHz
+// Th_scl      4.0us            0.6us   High period of SCL
+// Tl_scl      4.7us            1.3us   Low period of SCL
+// Tsu:sta     4.7us            0.6us   setup time for a repeated start condition
+// Tsu:sto     4.0us            0.6us   setup time for a stop conditon
+// Tbuf        4.7us            1.3us   Bus free time between a stop and start condition
+//
+
+// synopsys translate_off
+//`include "timescale.v"
+// synopsys translate_on
+
+`include "i2c_master_defines.v"
+
+module i2c_master_bit_ctrl(
+	clk, rst, nReset, 
+	clk_cnt, ena, cmd, cmd_ack, busy, al, din, dout,
+	scl_i, scl_o, scl_oen, sda_i, sda_o, sda_oen
+	);
+
+	//
+	// inputs & outputs
+	//
+	input clk;
+	input rst;
+	input nReset;
+	input ena;            // core enable signal
+
+	input [15:0] clk_cnt; // clock prescale value
+
+	input  [3:0] cmd;
+	output       cmd_ack; // command complete acknowledge
+	reg cmd_ack;
+	output       busy;    // i2c bus busy
+	reg busy;
+	output       al;      // i2c bus arbitration lost
+	reg al;
+
+	input  din;
+	output dout;
+	reg dout;
+
+	// I2C lines
+	input  scl_i;         // i2c clock line input
+	output scl_o;         // i2c clock line output
+	output scl_oen;       // i2c clock line output enable (active low)
+	reg scl_oen;
+	input  sda_i;         // i2c data line input
+	output sda_o;         // i2c data line output
+	output sda_oen;       // i2c data line output enable (active low)
+	reg sda_oen;
+
+
+	//
+	// variable declarations
+	//
+
+	reg sSCL, sSDA;             // synchronized SCL and SDA inputs
+	reg dscl_oen;               // delayed scl_oen
+	reg sda_chk;                // check SDA output (Multi-master arbitration)
+	reg clk_en;                 // clock generation signals
+	wire slave_wait;
+//	reg [15:0] cnt = clk_cnt;   // clock divider counter (simulation)
+	reg [15:0] cnt;             // clock divider counter (synthesis)
+
+	// state machine variable
+	reg [16:0] c_state; // synopsys enum_state
+
+	//
+	// module body
+	//
+
+	// whenever the slave is not ready it can delay the cycle by pulling SCL low
+	// delay scl_oen
+	always @(posedge clk)
+	  dscl_oen <= #1 scl_oen;
+
+	assign slave_wait = dscl_oen && !sSCL;
+
+
+	// generate clk enable signal
+	always @(posedge clk or negedge nReset)
+	  if(~nReset)
+	    begin
+	        cnt    <= #1 16'h0;
+	        clk_en <= #1 1'b1;
+	    end
+	  else if (rst)
+	    begin
+	        cnt    <= #1 16'h0;
+	        clk_en <= #1 1'b1;
+	    end
+	  else if ( ~|cnt || !ena)
+	    begin
+	        cnt    <= #1 clk_cnt;
+	        clk_en <= #1 1'b1;
+	    end
+	  else if (slave_wait)
+	    begin
+	        cnt    <= #1 cnt;
+	        clk_en <= #1 1'b0;    
+	    end
+	  else
+	    begin
+	        cnt    <= #1 cnt - 16'h1;
+	        clk_en <= #1 1'b0;
+	    end
+
+
+	// generate bus status controller
+	reg dSCL, dSDA;
+	reg sta_condition;
+	reg sto_condition;
+
+	// synchronize SCL and SDA inputs
+	// reduce metastability risc
+	always @(posedge clk or negedge nReset)
+	  if (~nReset)
+	    begin
+	        sSCL <= #1 1'b1;
+	        sSDA <= #1 1'b1;
+
+	        dSCL <= #1 1'b1;
+	        dSDA <= #1 1'b1;
+	    end
+	  else if (rst)
+	    begin
+	        sSCL <= #1 1'b1;
+	        sSDA <= #1 1'b1;
+
+	        dSCL <= #1 1'b1;
+	        dSDA <= #1 1'b1;
+	    end
+	  else
+	    begin
+	        sSCL <= #1 scl_i;
+	        sSDA <= #1 sda_i;
+
+	        dSCL <= #1 sSCL;
+	        dSDA <= #1 sSDA;
+	    end
+
+	// detect start condition => detect falling edge on SDA while SCL is high
+	// detect stop condition => detect rising edge on SDA while SCL is high
+	always @(posedge clk or negedge nReset)
+	  if (~nReset)
+	    begin
+	        sta_condition <= #1 1'b0;
+	        sto_condition <= #1 1'b0;
+	    end
+	  else if (rst)
+	    begin
+	        sta_condition <= #1 1'b0;
+	        sto_condition <= #1 1'b0;
+	    end
+	  else
+	    begin
+	        sta_condition <= #1 ~sSDA &  dSDA & sSCL;
+	        sto_condition <= #1  sSDA & ~dSDA & sSCL;
+	    end
+
+	// generate i2c bus busy signal
+	always @(posedge clk or negedge nReset)
+	  if(!nReset)
+	    busy <= #1 1'b0;
+	  else if (rst)
+	    busy <= #1 1'b0;
+	  else
+	    busy <= #1 (sta_condition | busy) & ~sto_condition;
+
+	// generate arbitration lost signal
+	// aribitration lost when:
+	// 1) master drives SDA high, but the i2c bus is low
+	// 2) stop detected while not requested
+	reg cmd_stop;
+	always @(posedge clk or negedge nReset)
+	  if (~nReset)
+	    cmd_stop <= #1 1'b0;
+	  else if (rst)
+	    cmd_stop <= #1 1'b0;
+	  else if (clk_en)
+	    cmd_stop <= #1 cmd == `I2C_CMD_STOP;
+
+	always @(posedge clk or negedge nReset)
+	  if (~nReset)
+	    al <= #1 1'b0;
+	  else if (rst)
+	    al <= #1 1'b0;
+	  else
+	    al <= #1 (sda_chk & ~sSDA & sda_oen) | (|c_state & sto_condition & ~cmd_stop);
+
+
+	// generate dout signal (store SDA on rising edge of SCL)
+	always @(posedge clk)
+	  if(sSCL & ~dSCL)
+	    dout <= #1 sSDA;
+
+	// generate statemachine
+
+	// nxt_state decoder
+	parameter [16:0] idle    = 17'b0_0000_0000_0000_0000;
+	parameter [16:0] start_a = 17'b0_0000_0000_0000_0001;
+	parameter [16:0] start_b = 17'b0_0000_0000_0000_0010;
+	parameter [16:0] start_c = 17'b0_0000_0000_0000_0100;
+	parameter [16:0] start_d = 17'b0_0000_0000_0000_1000;
+	parameter [16:0] start_e = 17'b0_0000_0000_0001_0000;
+	parameter [16:0] stop_a  = 17'b0_0000_0000_0010_0000;
+	parameter [16:0] stop_b  = 17'b0_0000_0000_0100_0000;
+	parameter [16:0] stop_c  = 17'b0_0000_0000_1000_0000;
+	parameter [16:0] stop_d  = 17'b0_0000_0001_0000_0000;
+	parameter [16:0] rd_a    = 17'b0_0000_0010_0000_0000;
+	parameter [16:0] rd_b    = 17'b0_0000_0100_0000_0000;
+	parameter [16:0] rd_c    = 17'b0_0000_1000_0000_0000;
+	parameter [16:0] rd_d    = 17'b0_0001_0000_0000_0000;
+	parameter [16:0] wr_a    = 17'b0_0010_0000_0000_0000;
+	parameter [16:0] wr_b    = 17'b0_0100_0000_0000_0000;
+	parameter [16:0] wr_c    = 17'b0_1000_0000_0000_0000;
+	parameter [16:0] wr_d    = 17'b1_0000_0000_0000_0000;
+
+	always @(posedge clk or negedge nReset)
+	  if (!nReset)
+	    begin
+	        c_state <= #1 idle;
+	        cmd_ack <= #1 1'b0;
+	        scl_oen <= #1 1'b1;
+	        sda_oen <= #1 1'b1;
+	        sda_chk <= #1 1'b0;
+	    end
+	  else if (rst | al)
+	    begin
+	        c_state <= #1 idle;
+	        cmd_ack <= #1 1'b0;
+	        scl_oen <= #1 1'b1;
+	        sda_oen <= #1 1'b1;
+	        sda_chk <= #1 1'b0;
+	    end
+	  else
+	    begin
+	        cmd_ack   <= #1 1'b0; // default no command acknowledge + assert cmd_ack only 1clk cycle
+
+	        if (clk_en)
+	          case (c_state) // synopsys full_case parallel_case
+	            // idle state
+	            idle:
+	            begin
+	                case (cmd) // synopsys full_case parallel_case
+	                  `I2C_CMD_START:
+	                     c_state <= #1 start_a;
+
+	                  `I2C_CMD_STOP:
+	                     c_state <= #1 stop_a;
+
+	                  `I2C_CMD_WRITE:
+	                     c_state <= #1 wr_a;
+
+	                  `I2C_CMD_READ:
+	                     c_state <= #1 rd_a;
+
+	                  default:
+	                    c_state <= #1 idle;
+	                endcase
+
+	                scl_oen <= #1 scl_oen; // keep SCL in same state
+	                sda_oen <= #1 sda_oen; // keep SDA in same state
+	                sda_chk <= #1 1'b0;    // don't check SDA output
+	            end
+
+	            // start
+	            start_a:
+	            begin
+	                c_state <= #1 start_b;
+	                scl_oen <= #1 scl_oen; // keep SCL in same state
+	                sda_oen <= #1 1'b1;    // set SDA high
+	                sda_chk <= #1 1'b0;    // don't check SDA output
+	            end
+
+	            start_b:
+	            begin
+	                c_state <= #1 start_c;
+	                scl_oen <= #1 1'b1; // set SCL high
+	                sda_oen <= #1 1'b1; // keep SDA high
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            start_c:
+	            begin
+	                c_state <= #1 start_d;
+	                scl_oen <= #1 1'b1; // keep SCL high
+	                sda_oen <= #1 1'b0; // set SDA low
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            start_d:
+	            begin
+	                c_state <= #1 start_e;
+	                scl_oen <= #1 1'b1; // keep SCL high
+	                sda_oen <= #1 1'b0; // keep SDA low
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            start_e:
+	            begin
+	                c_state <= #1 idle;
+	                cmd_ack <= #1 1'b1;
+	                scl_oen <= #1 1'b0; // set SCL low
+	                sda_oen <= #1 1'b0; // keep SDA low
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            // stop
+	            stop_a:
+	            begin
+	                c_state <= #1 stop_b;
+	                scl_oen <= #1 1'b0; // keep SCL low
+	                sda_oen <= #1 1'b0; // set SDA low
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            stop_b:
+	            begin
+	                c_state <= #1 stop_c;
+	                scl_oen <= #1 1'b1; // set SCL high
+	                sda_oen <= #1 1'b0; // keep SDA low
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            stop_c:
+	            begin
+	                c_state <= #1 stop_d;
+	                scl_oen <= #1 1'b1; // keep SCL high
+	                sda_oen <= #1 1'b0; // keep SDA low
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            stop_d:
+	            begin
+	                c_state <= #1 idle;
+	                cmd_ack <= #1 1'b1;
+	                scl_oen <= #1 1'b1; // keep SCL high
+	                sda_oen <= #1 1'b1; // set SDA high
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            // read
+	            rd_a:
+	            begin
+	                c_state <= #1 rd_b;
+	                scl_oen <= #1 1'b0; // keep SCL low
+	                sda_oen <= #1 1'b1; // tri-state SDA
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            rd_b:
+	            begin
+	                c_state <= #1 rd_c;
+	                scl_oen <= #1 1'b1; // set SCL high
+	                sda_oen <= #1 1'b1; // keep SDA tri-stated
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            rd_c:
+	            begin
+	                c_state <= #1 rd_d;
+	                scl_oen <= #1 1'b1; // keep SCL high
+	                sda_oen <= #1 1'b1; // keep SDA tri-stated
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            rd_d:
+	            begin
+	                c_state <= #1 idle;
+	                cmd_ack <= #1 1'b1;
+	                scl_oen <= #1 1'b0; // set SCL low
+	                sda_oen <= #1 1'b1; // keep SDA tri-stated
+	                sda_chk <= #1 1'b0; // don't check SDA output
+	            end
+
+	            // write
+	            wr_a:
+	            begin
+	                c_state <= #1 wr_b;
+	                scl_oen <= #1 1'b0; // keep SCL low
+	                sda_oen <= #1 din;  // set SDA
+	                sda_chk <= #1 1'b0; // don't check SDA output (SCL low)
+	            end
+
+	            wr_b:
+	            begin
+	                c_state <= #1 wr_c;
+	                scl_oen <= #1 1'b1; // set SCL high
+	                sda_oen <= #1 din;  // keep SDA
+	                sda_chk <= #1 1'b1; // check SDA output
+	            end
+
+	            wr_c:
+	            begin
+	                c_state <= #1 wr_d;
+	                scl_oen <= #1 1'b1; // keep SCL high
+	                sda_oen <= #1 din;
+	                sda_chk <= #1 1'b1; // check SDA output
+	            end
+
+	            wr_d:
+	            begin
+	                c_state <= #1 idle;
+	                cmd_ack <= #1 1'b1;
+	                scl_oen <= #1 1'b0; // set SCL low
+	                sda_oen <= #1 din;
+	                sda_chk <= #1 1'b0; // don't check SDA output (SCL low)
+	            end
+
+	          endcase
+	    end
+
+
+	// assign scl and sda output (always gnd)
+	assign scl_o = 1'b0;
+	assign sda_o = 1'b0;
+
+endmodule