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1 | // ========== Copyright Header Begin ========================================== |
2 | // | |
3 | // OpenSPARC T2 Processor File: dmu_clu_crm_arb.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 dmu_clu_crm_arb | |
36 | ( | |
37 | // clock/reset | |
38 | clk, | |
39 | rst_l, | |
40 | ||
41 | // ctl port | |
42 | grant, | |
43 | req, | |
44 | grnt_lck | |
45 | ); | |
46 | ||
47 | // synopsys sync_set_reset "rst_l" | |
48 | ||
49 | // >>>>>>>>>>>>>>>>>>>>>>>>> Parameter Declarations <<<<<<<<<<<<<<<<<<<<<<<<< | |
50 | ||
51 | parameter N = 3; | |
52 | ||
53 | // >>>>>>>>>>>>>>>>>>>>>>>>> Port Declarations <<<<<<<<<<<<<<<<<<<<<<<<<<<<<< | |
54 | ||
55 | // -------------------------------------------------------- | |
56 | // Clock/Reset Signals | |
57 | // -------------------------------------------------------- | |
58 | ||
59 | input clk; | |
60 | input rst_l; | |
61 | ||
62 | // -------------------------------------------------------- | |
63 | // Arbiter Control Port | |
64 | // -------------------------------------------------------- | |
65 | ||
66 | output [(N-1):0] grant; | |
67 | input [(N-1):0] req; | |
68 | input grnt_lck; | |
69 | ||
70 | // >>>>>>>>>>>>>>>>>>>>>>>>> Data Type Declarations <<<<<<<<<<<<<<<<<<<<<<<<< | |
71 | ||
72 | // ~~~~~~~~~~~~~~~~~~~~~~~~~ REGISTERS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
73 | ||
74 | // ********** Flops ********** | |
75 | ||
76 | reg [(N-1):0] pointer_reg; | |
77 | ||
78 | // ~~~~~~~~~~~~~~~~~~~~~~~~~ NETS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
79 | ||
80 | wire [(N-1):0] req_masked; | |
81 | wire [(N-1):0] mask_higher_pri_reqs; | |
82 | wire [(N-1):0] grant_masked; | |
83 | wire [(N-1):0] unmask_higher_pri_reqs; | |
84 | wire [(N-1):0] grant_unmasked; | |
85 | wire no_req_masked; | |
86 | wire mask_ptr_sel; | |
87 | wire unmask_ptr_sel; | |
88 | ||
89 | // >>>>>>>>>>>>>>>>>>>>>>>>> 0-in Checkers <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< | |
90 | ||
91 | /* 0in arb | |
92 | -req req[0] req[1] req[2] | |
93 | -gnt (grant[0] & ~grnt_lck) (grant[1] & ~grnt_lck) (grant[2] & ~grnt_lck) | |
94 | -round_robin | |
95 | -known_grant | |
96 | */ | |
97 | ||
98 | // >>>>>>>>>>>>>>>>>>>>>>>>> RTL Model <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< | |
99 | ||
100 | // -------------------------------------------------------- | |
101 | // Mask_Expand Round-Robin Arbiter | |
102 | // -------------------------------------------------------- | |
103 | ||
104 | // Simple priority arbitration for masked portion | |
105 | assign req_masked = req & pointer_reg; | |
106 | assign mask_higher_pri_reqs[N-1:1] = (mask_higher_pri_reqs[N-2: 0] | | |
107 | req_masked[N-2:0]); | |
108 | assign mask_higher_pri_reqs[0] = 1'b0; | |
109 | assign grant_masked[N-1:0] = (req_masked[N-1:0] & | |
110 | ~mask_higher_pri_reqs[N-1:0]); | |
111 | ||
112 | // Simple priority arbitration for unmasked portion | |
113 | assign unmask_higher_pri_reqs[N-1:1] = (unmask_higher_pri_reqs[N-2:0] | | |
114 | req[N-2:0]); | |
115 | assign unmask_higher_pri_reqs[0] = 1'b0; | |
116 | assign grant_unmasked[N-1:0] = req[N-1:0] & ~unmask_higher_pri_reqs[N-1:0]; | |
117 | ||
118 | // Use grant_masked if there is any there, otherwise use grant_unmasked | |
119 | assign no_req_masked = ~(|req_masked); | |
120 | assign grant = ({N{no_req_masked}} & grant_unmasked) | grant_masked; | |
121 | ||
122 | // Generate arbiter pointer update | |
123 | assign mask_ptr_sel = |req_masked & ~grnt_lck; | |
124 | assign unmask_ptr_sel = |req & ~grnt_lck; | |
125 | ||
126 | // Pointer update : only update if there's a req | |
127 | always @ (posedge clk) | |
128 | if (~rst_l) | |
129 | pointer_reg <= {N{1'b1}}; | |
130 | else if (mask_ptr_sel) // select if masked arbiter used | |
131 | pointer_reg <= mask_higher_pri_reqs; | |
132 | else if (unmask_ptr_sel) // select if unmasked arbiter used | |
133 | pointer_reg <= unmask_higher_pri_reqs; | |
134 | ||
135 | endmodule // dmu_clu_crm_arb |