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Diffstat (limited to 'src/rtl/i2c_regs.v')
| -rw-r--r-- | src/rtl/i2c_regs.v | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/src/rtl/i2c_regs.v b/src/rtl/i2c_regs.v new file mode 100644 index 0000000..e5ddb34 --- /dev/null +++ b/src/rtl/i2c_regs.v @@ -0,0 +1,127 @@ +//====================================================================== +// +// i2c.v +// ------ +// Configuration registers for the i2c core. +// +// +// Author: Joachim Strombergson +// Copyright (c) 2014, SUNET +// +// Redistribution and use in source and binary forms, with or +// without modification, are permitted provided that the following +// conditions are met: +// +// 1. Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// +// 2. Redistributions in binary form must reproduce the above copyright +// notice, this list of conditions and the following disclaimer in +// the documentation and/or other materials provided with the +// distribution. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE +// COPYRIGHT OWNER 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. +// +//====================================================================== + +module comm_regs + ( + input wire clk, + input wire rst, + + input wire cs, + input wire we, + + input wire [ 7 : 0] address, + input wire [31 : 0] write_data, + output wire [31 : 0] read_data + ); + + + //---------------------------------------------------------------- + // Internal constant and parameter definitions. + //---------------------------------------------------------------- + // API addresses. + localparam ADDR_CORE_NAME0 = 8'h00; + localparam ADDR_CORE_NAME1 = 8'h01; + localparam ADDR_CORE_VERSION = 8'h02; + localparam ADDR_DUMMY_REG = 8'hFF; // general-purpose register + + // Core ID constants. + localparam CORE_NAME0 = 32'h69326320; // "i2c " + localparam CORE_NAME1 = 32'h20202020; // " " + localparam CORE_VERSION = 32'h302e3130; // "0.10" + + + //---------------------------------------------------------------- + // Wires. + //---------------------------------------------------------------- + reg [31: 0] tmp_read_data; + + // dummy register to check that you can actually write something + reg [31: 0] reg_dummy; + + + //---------------------------------------------------------------- + // Concurrent connectivity for ports etc. + //---------------------------------------------------------------- + assign read_data = tmp_read_data; + + + //---------------------------------------------------------------- + // Access Handler + //---------------------------------------------------------------- + always @(posedge clk) + // + if (rst) begin + reg_dummy <= {32{1'b0}}; + end + else if (cs) begin + // + if (we) begin + // + // WRITE handler + // + case (address) + ADDR_DUMMY_REG: + reg_dummy <= write_data; + endcase + // + end else begin + // + // READ handler + // + case (address) + ADDR_CORE_NAME0: + tmp_read_data <= CORE_NAME0; + ADDR_CORE_NAME1: + tmp_read_data <= CORE_NAME1; + ADDR_CORE_VERSION: + tmp_read_data <= CORE_VERSION; + ADDR_DUMMY_REG: + tmp_read_data <= reg_dummy; + // + default: + tmp_read_data <= {32{1'b0}}; // read non-existent locations as zeroes + endcase + // + end + // + end + +endmodule + +//====================================================================== +// EOF i2c_regs.v +//====================================================================== |