1 /* 2 * Program for finding M & N values for DPLLs 3 * To be run on Host PC 4 * 5 * (C) Copyright 2010 6 * Texas Instruments, <www.ti.com> 7 * 8 * Aneesh V <aneesh@ti.com> 9 * 10 * See file CREDITS for list of people who contributed to this 11 * project. 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License as 15 * published by the Free Software Foundation; either version 2 of 16 * the License, or (at your option) any later version. 17 * 18 * This program is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21 * GNU General Public License for more details. 22 * 23 * You should have received a copy of the GNU General Public License 24 * along with this program; if not, write to the Free Software 25 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 26 * MA 02111-1307 USA 27 */ 28 #include <stdlib.h> 29 #include <stdio.h> 30 typedef unsigned int u32; 31 #define MAX_N 127 32 33 /* 34 * get_m_n_optimized() - Finds optimal DPLL multiplier(M) and divider(N) 35 * values based on the reference frequency, required output frequency, 36 * maximum tolerance for output frequency etc. 37 * 38 * target_freq_khz - output frequency required in KHz 39 * ref_freq_khz - reference(input) frequency in KHz 40 * m - pointer to computed M value 41 * n - pointer to computed N value 42 * tolerance_khz - tolerance for the output frequency. When the algorithm 43 * succeeds in finding vialble M and N values the corresponding output 44 * frequency will be in the range: 45 * [target_freq_khz - tolerance_khz, target_freq_khz] 46 * 47 * Formula: 48 * Fdpll = (2 * M * Fref) / (N + 1) 49 * 50 * Considerations for lock-time: 51 * - Smaller the N, better lock-time, especially lock-time will be 52 * - For acceptable lock-times: 53 * Fref / (M + 1) >= 1 MHz 54 * 55 * Considerations for power: 56 * - The difference in power for different N values giving the same 57 * output is negligible. So, we optimize for lock-time 58 * 59 * Hard-constraints: 60 * - N can not be greater than 127(7 bit field for representing N) 61 * 62 * Usage: 63 * $ gcc clocks_get_m_n.c 64 * $ ./a.out 65 */ 66 int get_m_n_optimized(u32 target_freq_khz, u32 ref_freq_khz, u32 *m, u32 *n, 67 u32 tolerance_khz) 68 { 69 u32 min_freq = target_freq_khz - tolerance_khz; 70 u32 max_freq = target_freq_khz; 71 u32 freq, freq_old; 72 *n = 1; 73 while (1) { 74 *m = min_freq / ref_freq_khz / 2 * (*n) ; 75 freq_old = 0; 76 while (1) { 77 freq = ref_freq_khz * 2 * (*m) / (*n); 78 if (abs(target_freq_khz - freq_old) <= 79 abs(target_freq_khz - freq)) { 80 freq = freq_old; 81 (*m)--; 82 break; 83 } 84 (*m)++; 85 freq_old = freq; 86 } 87 if (freq >= min_freq && freq <= max_freq) 88 break; 89 (*n)++; 90 if ((*n) > MAX_N + 1) { 91 printf("ref %d m %d n %d target %d : ", 92 ref_freq_khz, *m, *n, target_freq_khz); 93 printf("can not find m & n - please consider" 94 " increasing tolerance\n"); 95 return -1; 96 } 97 } 98 (*n)--; 99 printf("ref %d m %d n %d target %d locked %d\n", 100 ref_freq_khz, *m, *n, target_freq_khz, freq); 101 if ((ref_freq_khz / (*n + 1)) < 1000) { 102 printf("\tREFCLK - CLKINP/(N+1) is less than 1 MHz - less than" 103 " ideal, locking time will be high!\n"); 104 } 105 return 0; 106 } 107 108 void main(void) 109 { 110 u32 m, n; 111 printf("\nMPU - 2000000\n"); 112 get_m_n_optimized(2000000, 12000, &m, &n, 0); 113 get_m_n_optimized(2000000, 13000, &m, &n, 0); 114 get_m_n_optimized(2000000, 16800, &m, &n, 800); 115 get_m_n_optimized(2000000, 19200, &m, &n, 0); 116 get_m_n_optimized(2000000, 26000, &m, &n, 0); 117 get_m_n_optimized(2000000, 27000, &m, &n, 0); 118 get_m_n_optimized(2000000, 38400, &m, &n, 0); 119 120 printf("\nMPU - 1200000\n"); 121 get_m_n_optimized(1200000, 12000, &m, &n, 0); 122 get_m_n_optimized(1200000, 13000, &m, &n, 0); 123 get_m_n_optimized(1200000, 16800, &m, &n, 800); 124 get_m_n_optimized(1200000, 19200, &m, &n, 0); 125 get_m_n_optimized(1200000, 26000, &m, &n, 0); 126 get_m_n_optimized(1200000, 27000, &m, &n, 0); 127 get_m_n_optimized(1200000, 38400, &m, &n, 0); 128 129 printf("\nMPU - 1584000\n"); 130 get_m_n_optimized(1584000, 12000, &m, &n, 0); 131 get_m_n_optimized(1584000, 13000, &m, &n, 0); 132 get_m_n_optimized(1584000, 16800, &m, &n, 400); 133 get_m_n_optimized(1584000, 19200, &m, &n, 0); 134 get_m_n_optimized(1584000, 26000, &m, &n, 0); 135 get_m_n_optimized(1584000, 27000, &m, &n, 0); 136 get_m_n_optimized(1584000, 38400, &m, &n, 0); 137 138 printf("\nCore 1600000\n"); 139 get_m_n_optimized(1600000, 12000, &m, &n, 0); 140 get_m_n_optimized(1600000, 13000, &m, &n, 0); 141 get_m_n_optimized(1600000, 16800, &m, &n, 200); 142 get_m_n_optimized(1600000, 19200, &m, &n, 0); 143 get_m_n_optimized(1600000, 26000, &m, &n, 0); 144 get_m_n_optimized(1600000, 27000, &m, &n, 0); 145 get_m_n_optimized(1600000, 38400, &m, &n, 0); 146 147 printf("\nPER 1536000\n"); 148 get_m_n_optimized(1536000, 12000, &m, &n, 0); 149 get_m_n_optimized(1536000, 13000, &m, &n, 0); 150 get_m_n_optimized(1536000, 16800, &m, &n, 0); 151 get_m_n_optimized(1536000, 19200, &m, &n, 0); 152 get_m_n_optimized(1536000, 26000, &m, &n, 0); 153 get_m_n_optimized(1536000, 27000, &m, &n, 0); 154 get_m_n_optimized(1536000, 38400, &m, &n, 0); 155 156 printf("\nIVA 1862000\n"); 157 get_m_n_optimized(1862000, 12000, &m, &n, 0); 158 get_m_n_optimized(1862000, 13000, &m, &n, 0); 159 get_m_n_optimized(1862000, 16800, &m, &n, 0); 160 get_m_n_optimized(1862000, 19200, &m, &n, 900); 161 get_m_n_optimized(1862000, 26000, &m, &n, 0); 162 get_m_n_optimized(1862000, 27000, &m, &n, 0); 163 get_m_n_optimized(1862000, 38400, &m, &n, 800); 164 165 printf("\nABE 196608 sys clk\n"); 166 get_m_n_optimized(196608, 12000, &m, &n, 700); 167 get_m_n_optimized(196608, 13000, &m, &n, 200); 168 get_m_n_optimized(196608, 16800, &m, &n, 700); 169 get_m_n_optimized(196608, 19200, &m, &n, 400); 170 get_m_n_optimized(196608, 26000, &m, &n, 200); 171 get_m_n_optimized(196608, 27000, &m, &n, 900); 172 get_m_n_optimized(196608, 38400, &m, &n, 0); 173 174 printf("\nABE 196608 32K\n"); 175 get_m_n_optimized(196608000/4, 32768, &m, &n, 0); 176 177 printf("\nUSB 1920000\n"); 178 get_m_n_optimized(1920000, 12000, &m, &n, 0); 179 get_m_n_optimized(1920000, 13000, &m, &n, 0); 180 get_m_n_optimized(1920000, 16800, &m, &n, 0); 181 get_m_n_optimized(1920000, 19200, &m, &n, 0); 182 get_m_n_optimized(1920000, 26000, &m, &n, 0); 183 get_m_n_optimized(1920000, 27000, &m, &n, 0); 184 get_m_n_optimized(1920000, 38400, &m, &n, 0); 185 186 printf("\nCore ES1 1523712\n"); 187 get_m_n_optimized(1524000, 12000, &m, &n, 100); 188 get_m_n_optimized(1524000, 13000, &m, &n, 0); 189 get_m_n_optimized(1524000, 16800, &m, &n, 0); 190 get_m_n_optimized(1524000, 19200, &m, &n, 0); 191 get_m_n_optimized(1524000, 26000, &m, &n, 0); 192 get_m_n_optimized(1524000, 27000, &m, &n, 0); 193 194 /* exact recommendation for SDPs */ 195 get_m_n_optimized(1523712, 38400, &m, &n, 0); 196 197 } 198