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1 | // ========== Copyright Header Begin ========================================== |
2 | // | |
3 | // OpenSPARC T2 Processor File: pcie_common_dcs_ism.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_dcs_ism | |
36 | ( | |
37 | clk, // source clock | |
38 | rst_l, // reset | |
39 | csr_rng_cmd, // csr ring command | |
40 | osm2ism_deq, // osm dequeue | |
41 | ism2osm_vld, // osm valid | |
42 | ism2sdp_ds, // sdp data select | |
43 | ism2sdp_ld // sdp load | |
44 | ); | |
45 | ||
46 | // ---------------------------------------------------------------------------- | |
47 | // Parameters | |
48 | // ---------------------------------------------------------------------------- | |
49 | parameter QD = 3; // queue depth | |
50 | ||
51 | parameter IDLE = 2'b00, // state machine states | |
52 | LDMS = 2'b01, | |
53 | LDLS = 2'b10; | |
54 | ||
55 | // ---------------------------------------------------------------------------- | |
56 | // Ports | |
57 | // ---------------------------------------------------------------------------- | |
58 | input clk; | |
59 | input rst_l; | |
60 | input [`FIRE_CSR_CMND_BITS] csr_rng_cmd; | |
61 | input osm2ism_deq; | |
62 | ||
63 | output ism2osm_vld; | |
64 | output [QD-2:0] ism2sdp_ds; | |
65 | output [QD-1:0] ism2sdp_ld; | |
66 | ||
67 | // ---------------------------------------------------------------------------- | |
68 | // Variables | |
69 | // ---------------------------------------------------------------------------- | |
70 | wire ism2osm_vld, deq; | |
71 | ||
72 | reg [QD-2:0] ism2sdp_ds; | |
73 | reg [QD-1:0] ism2sdp_ld; | |
74 | reg [QD-1:0] vld, nxt_vld; | |
75 | reg [1:0] state, nxt_state; | |
76 | reg enq; | |
77 | ||
78 | integer i; | |
79 | ||
80 | // ---------------------------------------------------------------------------- | |
81 | // Zero In Checkers | |
82 | // ---------------------------------------------------------------------------- | |
83 | ||
84 | // 0in fifo -enq enq -deq deq -depth QD | |
85 | // 0in known_driven -var vld -active rst_l | |
86 | // 0in known_driven -var state -active rst_l | |
87 | // 0in state_transition -var state -val IDLE -next LDMS | |
88 | // 0in state_transition -var state -val LDMS -next LDLS | |
89 | // 0in state_transition -var state -val LDLS -next IDLE | |
90 | ||
91 | // ---------------------------------------------------------------------------- | |
92 | // Combinational | |
93 | // ---------------------------------------------------------------------------- | |
94 | ||
95 | // valid command | |
96 | wire rng_vld = |csr_rng_cmd; | |
97 | ||
98 | // next state | |
99 | always @ (state or rng_vld) begin | |
100 | case (state) // synopsys parallel_case | |
101 | IDLE : begin | |
102 | if (rng_vld) nxt_state = LDMS; | |
103 | else nxt_state = IDLE; | |
104 | end | |
105 | LDMS : nxt_state = LDLS; | |
106 | LDLS : nxt_state = IDLE; | |
107 | default : nxt_state = IDLE; | |
108 | endcase | |
109 | end | |
110 | ||
111 | // state outputs | |
112 | always @ (state or rng_vld) begin | |
113 | case (state) // synopsys parallel_case | |
114 | IDLE : enq = rng_vld; | |
115 | LDMS : enq = 1'b1; | |
116 | LDLS : enq = 1'b1; | |
117 | default : enq = 1'b0; | |
118 | endcase | |
119 | end | |
120 | ||
121 | // osm valid | |
122 | assign ism2osm_vld = vld[0]; | |
123 | ||
124 | // dequeue | |
125 | assign deq = osm2ism_deq; | |
126 | ||
127 | // queue controls | |
128 | always @ (rst_l or enq or deq or vld) begin | |
129 | for (i = 0; i < QD - 1; i = i + 1) ism2sdp_ds[i] = vld[i+1]; | |
130 | case ({enq, deq}) | |
131 | 2'b00 : ism2sdp_ld = ~{ QD { rst_l } }; | |
132 | 2'b01 : ism2sdp_ld = vld; | |
133 | 2'b10 : ism2sdp_ld = ~vld; | |
134 | 2'b11 : ism2sdp_ld = vld; | |
135 | endcase | |
136 | case ({enq, deq}) | |
137 | 2'b00 : nxt_vld = vld; | |
138 | 2'b01 : nxt_vld = { 1'b0, vld[QD-1:1] }; | |
139 | 2'b10 : nxt_vld = { vld[QD-2:0], 1'b1 }; | |
140 | 2'b11 : nxt_vld = vld; | |
141 | endcase | |
142 | end | |
143 | ||
144 | // ---------------------------------------------------------------------------- | |
145 | // Sequential | |
146 | // ---------------------------------------------------------------------------- | |
147 | always @ (posedge clk) begin | |
148 | if (!rst_l) begin | |
149 | vld <= 0; | |
150 | state <= IDLE; | |
151 | end | |
152 | else begin | |
153 | vld <= nxt_vld; | |
154 | state <= nxt_state; | |
155 | end | |
156 | end | |
157 | ||
158 | endmodule // pcie_common_dcs_ism |