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 * SPDX-License-Identifier: GPL-2.0+ 11 */ 12 #include <stdlib.h> 13 #include <stdio.h> 14 typedef unsigned int u32; 15 #define MAX_N 127 16 17 /* 18 * get_m_n_optimized() - Finds optimal DPLL multiplier(M) and divider(N) 19 * values based on the reference frequency, required output frequency, 20 * maximum tolerance for output frequency etc. 21 * 22 * target_freq_khz - output frequency required in KHz 23 * ref_freq_khz - reference(input) frequency in KHz 24 * m - pointer to computed M value 25 * n - pointer to computed N value 26 * tolerance_khz - tolerance for the output frequency. When the algorithm 27 * succeeds in finding vialble M and N values the corresponding output 28 * frequency will be in the range: 29 * [target_freq_khz - tolerance_khz, target_freq_khz] 30 * 31 * Formula: 32 * Fdpll = (2 * M * Fref) / (N + 1) 33 * 34 * Considerations for lock-time: 35 * - Smaller the N, better lock-time, especially lock-time will be 36 * - For acceptable lock-times: 37 * Fref / (M + 1) >= 1 MHz 38 * 39 * Considerations for power: 40 * - The difference in power for different N values giving the same 41 * output is negligible. So, we optimize for lock-time 42 * 43 * Hard-constraints: 44 * - N can not be greater than 127(7 bit field for representing N) 45 * 46 * Usage: 47 * $ gcc clocks_get_m_n.c 48 * $ ./a.out 49 */ 50 int get_m_n_optimized(u32 target_freq_khz, u32 ref_freq_khz, u32 *M, u32 *N) 51 { 52 u32 freq = target_freq_khz; 53 u32 m_optimal, n_optimal, freq_optimal = 0, freq_old; 54 u32 m, n; 55 n = 1; 56 while (1) { 57 m = target_freq_khz / ref_freq_khz / 2 * n; 58 freq_old = 0; 59 while (1) { 60 freq = ref_freq_khz * 2 * m / n; 61 if (freq > target_freq_khz) { 62 freq = freq_old; 63 m--; 64 break; 65 } 66 m++; 67 freq_old = freq; 68 } 69 if (freq > freq_optimal) { 70 freq_optimal = freq; 71 m_optimal = m; 72 n_optimal = n; 73 } 74 n++; 75 if ((freq_optimal == target_freq_khz) || 76 ((ref_freq_khz / n) < 1000)) { 77 break; 78 } 79 } 80 n--; 81 *M = m_optimal; 82 *N = n_optimal - 1; 83 printf("ref %d m %d n %d target %d locked %d\n", ref_freq_khz, 84 m_optimal, n_optimal - 1, target_freq_khz, freq_optimal); 85 return 0; 86 } 87 88 void main(void) 89 { 90 u32 m, n; 91 printf("\nMPU - 2000000\n"); 92 get_m_n_optimized(2000000, 12000, &m, &n); 93 get_m_n_optimized(2000000, 13000, &m, &n); 94 get_m_n_optimized(2000000, 16800, &m, &n); 95 get_m_n_optimized(2000000, 19200, &m, &n); 96 get_m_n_optimized(2000000, 26000, &m, &n); 97 get_m_n_optimized(2000000, 27000, &m, &n); 98 get_m_n_optimized(2000000, 38400, &m, &n); 99 100 printf("\nMPU - 1200000\n"); 101 get_m_n_optimized(1200000, 12000, &m, &n); 102 get_m_n_optimized(1200000, 13000, &m, &n); 103 get_m_n_optimized(1200000, 16800, &m, &n); 104 get_m_n_optimized(1200000, 19200, &m, &n); 105 get_m_n_optimized(1200000, 26000, &m, &n); 106 get_m_n_optimized(1200000, 27000, &m, &n); 107 get_m_n_optimized(1200000, 38400, &m, &n); 108 109 printf("\nMPU - 1584000\n"); 110 get_m_n_optimized(1584000, 12000, &m, &n); 111 get_m_n_optimized(1584000, 13000, &m, &n); 112 get_m_n_optimized(1584000, 16800, &m, &n); 113 get_m_n_optimized(1584000, 19200, &m, &n); 114 get_m_n_optimized(1584000, 26000, &m, &n); 115 get_m_n_optimized(1584000, 27000, &m, &n); 116 get_m_n_optimized(1584000, 38400, &m, &n); 117 118 printf("\nCore 1600000\n"); 119 get_m_n_optimized(1600000, 12000, &m, &n); 120 get_m_n_optimized(1600000, 13000, &m, &n); 121 get_m_n_optimized(1600000, 16800, &m, &n); 122 get_m_n_optimized(1600000, 19200, &m, &n); 123 get_m_n_optimized(1600000, 26000, &m, &n); 124 get_m_n_optimized(1600000, 27000, &m, &n); 125 get_m_n_optimized(1600000, 38400, &m, &n); 126 127 printf("\nPER 1536000\n"); 128 get_m_n_optimized(1536000, 12000, &m, &n); 129 get_m_n_optimized(1536000, 13000, &m, &n); 130 get_m_n_optimized(1536000, 16800, &m, &n); 131 get_m_n_optimized(1536000, 19200, &m, &n); 132 get_m_n_optimized(1536000, 26000, &m, &n); 133 get_m_n_optimized(1536000, 27000, &m, &n); 134 get_m_n_optimized(1536000, 38400, &m, &n); 135 136 printf("\nIVA 1862000\n"); 137 get_m_n_optimized(1862000, 12000, &m, &n); 138 get_m_n_optimized(1862000, 13000, &m, &n); 139 get_m_n_optimized(1862000, 16800, &m, &n); 140 get_m_n_optimized(1862000, 19200, &m, &n); 141 get_m_n_optimized(1862000, 26000, &m, &n); 142 get_m_n_optimized(1862000, 27000, &m, &n); 143 get_m_n_optimized(1862000, 38400, &m, &n); 144 145 printf("\nIVA Nitro - 1290000\n"); 146 get_m_n_optimized(1290000, 12000, &m, &n); 147 get_m_n_optimized(1290000, 13000, &m, &n); 148 get_m_n_optimized(1290000, 16800, &m, &n); 149 get_m_n_optimized(1290000, 19200, &m, &n); 150 get_m_n_optimized(1290000, 26000, &m, &n); 151 get_m_n_optimized(1290000, 27000, &m, &n); 152 get_m_n_optimized(1290000, 38400, &m, &n); 153 154 printf("\nABE 196608 sys clk\n"); 155 get_m_n_optimized(196608, 12000, &m, &n); 156 get_m_n_optimized(196608, 13000, &m, &n); 157 get_m_n_optimized(196608, 16800, &m, &n); 158 get_m_n_optimized(196608, 19200, &m, &n); 159 get_m_n_optimized(196608, 26000, &m, &n); 160 get_m_n_optimized(196608, 27000, &m, &n); 161 get_m_n_optimized(196608, 38400, &m, &n); 162 163 printf("\nABE 196608 32K\n"); 164 get_m_n_optimized(196608000/4, 32768, &m, &n); 165 166 printf("\nUSB 1920000\n"); 167 get_m_n_optimized(1920000, 12000, &m, &n); 168 get_m_n_optimized(1920000, 13000, &m, &n); 169 get_m_n_optimized(1920000, 16800, &m, &n); 170 get_m_n_optimized(1920000, 19200, &m, &n); 171 get_m_n_optimized(1920000, 26000, &m, &n); 172 get_m_n_optimized(1920000, 27000, &m, &n); 173 get_m_n_optimized(1920000, 38400, &m, &n); 174 175 printf("\nCore ES1 1523712\n"); 176 get_m_n_optimized(1524000, 12000, &m, &n); 177 get_m_n_optimized(1524000, 13000, &m, &n); 178 get_m_n_optimized(1524000, 16800, &m, &n); 179 get_m_n_optimized(1524000, 19200, &m, &n); 180 get_m_n_optimized(1524000, 26000, &m, &n); 181 get_m_n_optimized(1524000, 27000, &m, &n); 182 183 /* exact recommendation for SDPs */ 184 get_m_n_optimized(1523712, 38400, &m, &n); 185 186 } 187