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1 | // ========== Copyright Header Begin ========================================== |
2 | // | |
3 | // OpenSPARC T2 Processor File: niu_pio_ucb_in32.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 | //////////////////////////////////////////////////////////////////////////////// | |
36 | // | |
37 | // | |
38 | // Copyright (C) 2003 by Sun Microsystems, Inc. | |
39 | // | |
40 | // All rights reserved. No part of this design may be reproduced, | |
41 | // stored in a retrieval system, or transmitted, in any form or by | |
42 | // any means, electronic, mechanical, photocopying, recording, or | |
43 | // otherwise, without prior written permission of Sun Microsystems, | |
44 | // Inc. | |
45 | // | |
46 | // Sun Proprietary/Confidential | |
47 | // | |
48 | // | |
49 | // Primary Contact: Jimmy.Lau@sun.com x48745 | |
50 | // Description: This interface is modified based on Niagra ucb_bus_in. | |
51 | // Instaniated by UCB modules and NCU to receive | |
52 | // packets on the UCB bus. This module supports 32 bit | |
53 | // data bus in. | |
54 | // | |
55 | // Revision: 1. March 08, 2004 - John Lo | |
56 | // Changed modules name from | |
57 | // ucb_bus_in32_niu.v to niu_pio_ucb_in32 | |
58 | // | |
59 | // Changed enl2clk to clk. | |
60 | // | |
61 | // | |
62 | //////////////////////////////////////////////////////////////////////////////// | |
63 | ||
64 | ||
65 | module niu_pio_ucb_in32 ( | |
66 | // Global // | |
67 | reset, | |
68 | clk, | |
69 | // UCB bus // | |
70 | vld, | |
71 | data, | |
72 | stall, | |
73 | // local unit // | |
74 | indata_buf_vld, | |
75 | indata_buf, | |
76 | stall_a1 ); | |
77 | ||
78 | // Global interface | |
79 | input reset; | |
80 | input clk; | |
81 | ||
82 | ||
83 | // UCB bus interface | |
84 | input vld; | |
85 | input [31:0] data; | |
86 | output stall; | |
87 | ||
88 | ||
89 | // Local interface | |
90 | output indata_buf_vld; | |
91 | output [127:0] indata_buf; | |
92 | input stall_a1; | |
93 | ||
94 | // Internal signals | |
95 | wire vld_d1; | |
96 | wire stall_d1; | |
97 | wire [31:0] data_d1; | |
98 | wire skid_buf0_en; | |
99 | wire vld_buf0; | |
100 | wire [31:0] data_buf0; | |
101 | wire skid_buf1_en; | |
102 | wire vld_buf1; | |
103 | wire [31:0] data_buf1; | |
104 | wire skid_buf0_sel; | |
105 | wire skid_buf1_sel; | |
106 | wire vld_mux; | |
107 | wire [31:0] data_mux; | |
108 | wire [3:0] indata_vec_next; | |
109 | wire [3:0] indata_vec; | |
110 | wire [127:0] indata_buf_next; | |
111 | wire indata_vec0_d1; | |
112 | wire stall_a1_inv; | |
113 | ||
114 | ||
115 | //////////////////////////////////////////////////////////////////////// | |
116 | // Code starts here | |
117 | //////////////////////////////////////////////////////////////////////// | |
118 | /************************************************************ | |
119 | * UCB bus interface flops | |
120 | * This is to make signals going between NCU and UCB flop-to-flop | |
121 | * to improve timing. | |
122 | ************************************************************/ | |
123 | dffre #(1) vld_d1_ff (.d(vld), | |
124 | .reset(reset), | |
125 | .en(~stall_d1), | |
126 | .clk(clk), | |
127 | .q(vld_d1) ); | |
128 | ||
129 | dffe #(32) data_d1_ff (.d(data[31:0]), | |
130 | .en(~stall_d1), | |
131 | .clk(clk), | |
132 | .q(data_d1[31:0]) ); | |
133 | ||
134 | dffr #(1) stall_ff (.d(stall_a1), | |
135 | .clk(clk), | |
136 | .reset(reset), | |
137 | .q(stall) ); | |
138 | ||
139 | dffr #(1) stall_d1_ff (.d(stall), | |
140 | .clk(clk), | |
141 | .reset(reset), | |
142 | .q(stall_d1) ); | |
143 | ||
144 | ||
145 | /************************************************************ | |
146 | * Skid buffer | |
147 | * We need a two deep skid buffer to handle stalling. | |
148 | ************************************************************/ | |
149 | // Assertion: stall has to be deasserted for more than 1 cycle | |
150 | // ie time between two separate stalls has to be | |
151 | // at least two cycles. Otherwise, contents from | |
152 | // skid buffer will be lost. | |
153 | ||
154 | // Buffer 0 | |
155 | assign skid_buf0_en = stall_a1 & ~stall; | |
156 | ||
157 | dffre #(1) vld_buf0_ff (.d(vld_d1), | |
158 | .reset(reset), | |
159 | .en(skid_buf0_en), | |
160 | .clk(clk), | |
161 | .q(vld_buf0) ); | |
162 | ||
163 | dffe #(32) data_buf0_ff (.d(data_d1[31:0]), | |
164 | .en(skid_buf0_en), | |
165 | .clk(clk), | |
166 | .q(data_buf0[31:0]) ); | |
167 | ||
168 | // Buffer 1 | |
169 | dffr #(1) skid_buf1_en_ff (.d(skid_buf0_en), | |
170 | .clk(clk), | |
171 | .reset(reset), | |
172 | .q(skid_buf1_en) ); | |
173 | ||
174 | dffre #(1) vld_buf1_ff (.d(vld_d1), | |
175 | .reset(reset), | |
176 | .en(skid_buf1_en), | |
177 | .clk(clk), | |
178 | .q(vld_buf1) ); | |
179 | ||
180 | dffe #(32) data_buf1_ff (.d(data_d1[31:0]), | |
181 | .en(skid_buf1_en), | |
182 | .clk(clk), | |
183 | .q(data_buf1[31:0]) ); | |
184 | ||
185 | /************************************************************ | |
186 | * Mux between skid buffer and interface flop | |
187 | ************************************************************/ | |
188 | // Assertion: stall has to be deasserted for more than 1 cycle | |
189 | // ie time between two separate stalls has to be | |
190 | // at least two cycles. Otherwise, contents from | |
191 | // skid buffer will be lost. | |
192 | ||
193 | assign skid_buf0_sel = ~stall_a1 & stall; | |
194 | ||
195 | dffr #(1) skid_buf1_sel_ff (.d(skid_buf0_sel), | |
196 | .clk(clk), | |
197 | .reset(reset), | |
198 | .q(skid_buf1_sel) ); | |
199 | ||
200 | assign vld_mux = skid_buf0_sel ? vld_buf0 : | |
201 | skid_buf1_sel ? vld_buf1 : vld_d1; | |
202 | ||
203 | assign data_mux[31:0] = skid_buf0_sel ? data_buf0[31:0] : | |
204 | skid_buf1_sel ? data_buf1[31:0] : data_d1[31:0]; | |
205 | ||
206 | ||
207 | /************************************************************ | |
208 | * Assemble inbound data | |
209 | ************************************************************/ | |
210 | // valid vector | |
211 | assign indata_vec_next[3:0] = {vld_mux,indata_vec[3:1]}; | |
212 | assign stall_a1_inv = ~stall_a1 ; | |
213 | dffre #(4) indata_vec_ff (.d(indata_vec_next[3:0]), | |
214 | .en(stall_a1_inv), | |
215 | .reset(reset), | |
216 | .clk(clk), | |
217 | .q(indata_vec[3:0]) ); | |
218 | ||
219 | // data buffer | |
220 | assign indata_buf_next[127:0] = {data_mux[31:0],indata_buf[127:32]}; | |
221 | dffe #(128) indata_buf_ff (.d(indata_buf_next[127:0]), | |
222 | .en(stall_a1_inv), | |
223 | .clk(clk), | |
224 | .q(indata_buf[127:0]) ); | |
225 | ||
226 | // detect a new packet | |
227 | dffre #(1) indata_vec0_d1_ff (.d(indata_vec[0]), | |
228 | .reset(reset), | |
229 | .en(stall_a1_inv), | |
230 | .clk(clk), | |
231 | .q(indata_vec0_d1) ); | |
232 | ||
233 | assign indata_buf_vld = indata_vec[0] & ~indata_vec0_d1; | |
234 | ||
235 | ||
236 | endmodule // niu_pio_ucb_in32 | |
237 |