1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Program for finding M & N values for DPLLs 4 * To be run on Host PC 5 * 6 * (C) Copyright 2010 7 * Texas Instruments, <www.ti.com> 8 * 9 * Aneesh V <aneesh (at) ti.com> 10 */ 11 #include <stdlib.h> 12 #include <stdio.h> 13 typedef unsigned int u32; 14 #define MAX_N 127 15 16 /* 17 * get_m_n_optimized() - Finds optimal DPLL multiplier(M) and divider(N) 18 * values based on the reference frequency, required output frequency, 19 * maximum tolerance for output frequency etc. 20 * 21 * target_freq_khz - output frequency required in KHz 22 * ref_freq_khz - reference(input) frequency in KHz 23 * m - pointer to computed M value 24 * n - pointer to computed N value 25 * tolerance_khz - tolerance for the output frequency. When the algorithm 26 * succeeds in finding vialble M and N values the corresponding output 27 * frequency will be in the range: 28 * [target_freq_khz - tolerance_khz, target_freq_khz] 29 * 30 * Formula: 31 * Fdpll = (2 * M * Fref) / (N + 1) 32 * 33 * Considerations for lock-time: 34 * - Smaller the N, better lock-time, especially lock-time will be 35 * - For acceptable lock-times: 36 * Fref / (M + 1) >= 1 MHz 37 * 38 * Considerations for power: 39 * - The difference in power for different N values giving the same 40 * output is negligible. So, we optimize for lock-time 41 * 42 * Hard-constraints: 43 * - N can not be greater than 127(7 bit field for representing N) 44 * 45 * Usage: 46 * $ gcc clocks_get_m_n.c 47 * $ ./a.out 48 */ 49 int get_m_n_optimized(u32 target_freq_khz, u32 ref_freq_khz, u32 *M, u32 *N) 50 { 51 u32 freq = target_freq_khz; 52 u32 m_optimal, n_optimal, freq_optimal = 0, freq_old; 53 u32 m, n; 54 n = 1; 55 while (1) { 56 m = target_freq_khz / ref_freq_khz / 2 * n; 57 freq_old = 0; 58 while (1) { 59 freq = ref_freq_khz * 2 * m / n; 60 if (freq > target_freq_khz) { 61 freq = freq_old; 62 m--; 63 break; 64 } 65 m++; 66 freq_old = freq; 67 } 68 if (freq > freq_optimal) { 69 freq_optimal = freq; 70 m_optimal = m; 71 n_optimal = n; 72 } 73 n++; 74 if ((freq_optimal == target_freq_khz) || 75 ((ref_freq_khz / n) < 1000)) { 76 break; 77 } 78 } 79 n--; 80 *M = m_optimal; 81 *N = n_optimal - 1; 82 printf("ref %d m %d n %d target %d locked %d\n", ref_freq_khz, 83 m_optimal, n_optimal - 1, target_freq_khz, freq_optimal); 84 return 0; 85 } 86 87 void main(void) 88 { 89 u32 m, n; 90 printf("\nMPU - 2000000\n"); 91 get_m_n_optimized(2000000, 12000, &m, &n); 92 get_m_n_optimized(2000000, 13000, &m, &n); 93 get_m_n_optimized(2000000, 16800, &m, &n); 94 get_m_n_optimized(2000000, 19200, &m, &n); 95 get_m_n_optimized(2000000, 26000, &m, &n); 96 get_m_n_optimized(2000000, 27000, &m, &n); 97 get_m_n_optimized(2000000, 38400, &m, &n); 98 99 printf("\nMPU - 1200000\n"); 100 get_m_n_optimized(1200000, 12000, &m, &n); 101 get_m_n_optimized(1200000, 13000, &m, &n); 102 get_m_n_optimized(1200000, 16800, &m, &n); 103 get_m_n_optimized(1200000, 19200, &m, &n); 104 get_m_n_optimized(1200000, 26000, &m, &n); 105 get_m_n_optimized(1200000, 27000, &m, &n); 106 get_m_n_optimized(1200000, 38400, &m, &n); 107 108 printf("\nMPU - 1584000\n"); 109 get_m_n_optimized(1584000, 12000, &m, &n); 110 get_m_n_optimized(1584000, 13000, &m, &n); 111 get_m_n_optimized(1584000, 16800, &m, &n); 112 get_m_n_optimized(1584000, 19200, &m, &n); 113 get_m_n_optimized(1584000, 26000, &m, &n); 114 get_m_n_optimized(1584000, 27000, &m, &n); 115 get_m_n_optimized(1584000, 38400, &m, &n); 116 117 printf("\nCore 1600000\n"); 118 get_m_n_optimized(1600000, 12000, &m, &n); 119 get_m_n_optimized(1600000, 13000, &m, &n); 120 get_m_n_optimized(1600000, 16800, &m, &n); 121 get_m_n_optimized(1600000, 19200, &m, &n); 122 get_m_n_optimized(1600000, 26000, &m, &n); 123 get_m_n_optimized(1600000, 27000, &m, &n); 124 get_m_n_optimized(1600000, 38400, &m, &n); 125 126 printf("\nPER 1536000\n"); 127 get_m_n_optimized(1536000, 12000, &m, &n); 128 get_m_n_optimized(1536000, 13000, &m, &n); 129 get_m_n_optimized(1536000, 16800, &m, &n); 130 get_m_n_optimized(1536000, 19200, &m, &n); 131 get_m_n_optimized(1536000, 26000, &m, &n); 132 get_m_n_optimized(1536000, 27000, &m, &n); 133 get_m_n_optimized(1536000, 38400, &m, &n); 134 135 printf("\nIVA 1862000\n"); 136 get_m_n_optimized(1862000, 12000, &m, &n); 137 get_m_n_optimized(1862000, 13000, &m, &n); 138 get_m_n_optimized(1862000, 16800, &m, &n); 139 get_m_n_optimized(1862000, 19200, &m, &n); 140 get_m_n_optimized(1862000, 26000, &m, &n); 141 get_m_n_optimized(1862000, 27000, &m, &n); 142 get_m_n_optimized(1862000, 38400, &m, &n); 143 144 printf("\nIVA Nitro - 1290000\n"); 145 get_m_n_optimized(1290000, 12000, &m, &n); 146 get_m_n_optimized(1290000, 13000, &m, &n); 147 get_m_n_optimized(1290000, 16800, &m, &n); 148 get_m_n_optimized(1290000, 19200, &m, &n); 149 get_m_n_optimized(1290000, 26000, &m, &n); 150 get_m_n_optimized(1290000, 27000, &m, &n); 151 get_m_n_optimized(1290000, 38400, &m, &n); 152 153 printf("\nABE 196608 sys clk\n"); 154 get_m_n_optimized(196608, 12000, &m, &n); 155 get_m_n_optimized(196608, 13000, &m, &n); 156 get_m_n_optimized(196608, 16800, &m, &n); 157 get_m_n_optimized(196608, 19200, &m, &n); 158 get_m_n_optimized(196608, 26000, &m, &n); 159 get_m_n_optimized(196608, 27000, &m, &n); 160 get_m_n_optimized(196608, 38400, &m, &n); 161 162 printf("\nABE 196608 32K\n"); 163 get_m_n_optimized(196608000/4, 32768, &m, &n); 164 165 printf("\nUSB 1920000\n"); 166 get_m_n_optimized(1920000, 12000, &m, &n); 167 get_m_n_optimized(1920000, 13000, &m, &n); 168 get_m_n_optimized(1920000, 16800, &m, &n); 169 get_m_n_optimized(1920000, 19200, &m, &n); 170 get_m_n_optimized(1920000, 26000, &m, &n); 171 get_m_n_optimized(1920000, 27000, &m, &n); 172 get_m_n_optimized(1920000, 38400, &m, &n); 173 174 printf("\nCore ES1 1523712\n"); 175 get_m_n_optimized(1524000, 12000, &m, &n); 176 get_m_n_optimized(1524000, 13000, &m, &n); 177 get_m_n_optimized(1524000, 16800, &m, &n); 178 get_m_n_optimized(1524000, 19200, &m, &n); 179 get_m_n_optimized(1524000, 26000, &m, &n); 180 get_m_n_optimized(1524000, 27000, &m, &n); 181 182 /* exact recommendation for SDPs */ 183 get_m_n_optimized(1523712, 38400, &m, &n); 184 185 } 186
