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1 | // ========== Copyright Header Begin ========================================== |
2 | // | |
3 | // OpenSPARC T2 Processor File: pcie_common_dcd.v | |
4 | // Copyright (C) 1995-2007 Sun Microsystems, Inc. All Rights Reserved | |
5 | // 4150 Network Circle, Santa Clara, California 95054, U.S.A. | |
6 | // | |
7 | // * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
8 | // | |
9 | // This program is free software; you can redistribute it and/or modify | |
10 | // it under the terms of the GNU General Public License as published by | |
11 | // the Free Software Foundation; version 2 of the License. | |
12 | // | |
13 | // This program is distributed in the hope that it will be useful, | |
14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | // GNU General Public License for more details. | |
17 | // | |
18 | // You should have received a copy of the GNU General Public License | |
19 | // along with this program; if not, write to the Free Software | |
20 | // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
21 | // | |
22 | // For the avoidance of doubt, and except that if any non-GPL license | |
23 | // choice is available it will apply instead, Sun elects to use only | |
24 | // the General Public License version 2 (GPLv2) at this time for any | |
25 | // software where a choice of GPL license versions is made | |
26 | // available with the language indicating that GPLv2 or any later version | |
27 | // may be used, or where a choice of which version of the GPL is applied is | |
28 | // otherwise unspecified. | |
29 | // | |
30 | // Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
31 | // CA 95054 USA or visit www.sun.com if you need additional information or | |
32 | // have any questions. | |
33 | // | |
34 | // ========== Copyright Header End ============================================ | |
35 | module pcie_common_dcd | |
36 | ( | |
37 | clk, // destination clock | |
38 | rst_l, // reset | |
39 | csr_pkt_data, // packet data | |
40 | csr_pkt_req, // packet request | |
41 | csr_pkt_ack, // packet acknowledge | |
42 | csr_rng_data // ring data | |
43 | ); | |
44 | ||
45 | // ---------------------------------------------------------------------------- | |
46 | // Parameters | |
47 | // ---------------------------------------------------------------------------- | |
48 | parameter IDLE = 2'b00, // state machine states | |
49 | LDMS = 2'b01, | |
50 | LDLS = 2'b10; | |
51 | ||
52 | // ---------------------------------------------------------------------------- | |
53 | // Ports | |
54 | // ---------------------------------------------------------------------------- | |
55 | input clk; | |
56 | input rst_l; | |
57 | input [`FIRE_CSR_PCKT_BITS] csr_pkt_data; | |
58 | input csr_pkt_req; | |
59 | ||
60 | output csr_pkt_ack; | |
61 | output [`FIRE_CSR_RING_BITS] csr_rng_data; | |
62 | ||
63 | // ---------------------------------------------------------------------------- | |
64 | // Variables | |
65 | // ---------------------------------------------------------------------------- | |
66 | wire req; | |
67 | ||
68 | reg [`FIRE_CSR_RING_BITS] csr_rng_data, nxt_rng; | |
69 | reg [1:0] state, nxt_state; | |
70 | reg [1:0] sel; | |
71 | reg ack, nxt_ack; | |
72 | ||
73 | // ---------------------------------------------------------------------------- | |
74 | // Zero In Checkers | |
75 | // ---------------------------------------------------------------------------- | |
76 | ||
77 | // 0in known_driven -var ack -active rst_l | |
78 | // 0in known_driven -var state -active rst_l | |
79 | // 0in state_transition -var state -val IDLE -next LDMS | |
80 | // 0in state_transition -var state -val LDMS -next LDLS | |
81 | // 0in state_transition -var state -val LDLS -next IDLE | |
82 | ||
83 | // ---------------------------------------------------------------------------- | |
84 | // Instantiations | |
85 | // ---------------------------------------------------------------------------- | |
86 | /* N2- AT 03/04/05: | |
87 | pcie_common_sync_flop #(1'b1) sff | |
88 | ( | |
89 | .clk (clk), | |
90 | .din (csr_pkt_req), | |
91 | .dout (req) | |
92 | ); | |
93 | END N2- AT 03/04/05 */ | |
94 | ||
95 | // N2+ AT 03/04/05: repalce pcie_common_sync_flop w/ sync cells from N2 lib. | |
96 | cl_a1_clksyncff_4x sff( | |
97 | .siclk (1'b0), | |
98 | .soclk (1'b0), | |
99 | .si (1'b0), | |
100 | .so (), | |
101 | .l1clk (clk), | |
102 | .d (csr_pkt_req), | |
103 | .q (req) | |
104 | ); | |
105 | // END N2+ AT 03/04/05 | |
106 | ||
107 | // ---------------------------------------------------------------------------- | |
108 | // Combinational | |
109 | // ---------------------------------------------------------------------------- | |
110 | wire csr_pkt_ack = ack; | |
111 | ||
112 | // next state | |
113 | always @ (state or req or ack) begin | |
114 | case (state) // synopsys parallel_case | |
115 | IDLE : begin | |
116 | if (req ^ ack) nxt_state = LDMS; | |
117 | else nxt_state = IDLE; | |
118 | end | |
119 | LDMS : nxt_state = LDLS; | |
120 | LDLS : nxt_state = IDLE; | |
121 | default : nxt_state = IDLE; | |
122 | endcase | |
123 | end | |
124 | ||
125 | // state outputs | |
126 | always @ (state or nxt_state or ack) begin | |
127 | case (state) // synopsys parallel_case | |
128 | IDLE : begin | |
129 | case (nxt_state) // synopsys parallel_case | |
130 | LDMS : begin | |
131 | nxt_ack = ack; | |
132 | sel = 2'b01; | |
133 | end | |
134 | default : begin | |
135 | nxt_ack = ack; | |
136 | sel = 2'b00; | |
137 | end | |
138 | endcase | |
139 | end | |
140 | LDMS : begin | |
141 | nxt_ack = ack; | |
142 | sel = 2'b10; | |
143 | end | |
144 | LDLS : begin | |
145 | nxt_ack = ~ack; | |
146 | sel = 2'b11; | |
147 | end | |
148 | default : begin | |
149 | nxt_ack = ack; | |
150 | sel = 2'b00; | |
151 | end | |
152 | endcase | |
153 | end | |
154 | ||
155 | // next ring | |
156 | always @ (sel or csr_pkt_data) begin | |
157 | case (sel) // synopsys infer_mux | |
158 | 2'b00 : nxt_rng = 0; | |
159 | 2'b01 : nxt_rng = csr_pkt_data[`FIRE_CSR_PCKT_ADDR_BITS]; | |
160 | 2'b10 : nxt_rng = csr_pkt_data[`FIRE_CSR_PCKT_RDMS_BITS]; | |
161 | 2'b11 : nxt_rng = csr_pkt_data[`FIRE_CSR_PCKT_RDLS_BITS]; | |
162 | endcase | |
163 | end | |
164 | ||
165 | // ---------------------------------------------------------------------------- | |
166 | // Sequential | |
167 | // ---------------------------------------------------------------------------- | |
168 | always @ (posedge clk) begin | |
169 | if (!rst_l) begin | |
170 | ack <= 0; | |
171 | state <= IDLE; | |
172 | end | |
173 | else begin | |
174 | ack <= nxt_ack; | |
175 | state <= nxt_state; | |
176 | end | |
177 | end | |
178 | ||
179 | always @ (posedge clk) | |
180 | if (!rst_l) begin | |
181 | csr_rng_data <= {32{1'b0}}; | |
182 | end | |
183 | else begin | |
184 | csr_rng_data <= nxt_rng; | |
185 | end | |
186 | ||
187 | endmodule // pcie_common_dcd |