clocks_get_m_n.c
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/*
* Program for finding M & N values for DPLLs
* To be run on Host PC
*
* (C) Copyright 2010
* Texas Instruments, <www.ti.com>
*
* Aneesh V <aneesh@ti.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <stdlib.h>
#include <stdio.h>
typedef unsigned int u32;
#define MAX_N 127
/*
* get_m_n_optimized() - Finds optimal DPLL multiplier(M) and divider(N)
* values based on the reference frequency, required output frequency,
* maximum tolerance for output frequency etc.
*
* target_freq_khz - output frequency required in KHz
* ref_freq_khz - reference(input) frequency in KHz
* m - pointer to computed M value
* n - pointer to computed N value
* tolerance_khz - tolerance for the output frequency. When the algorithm
* succeeds in finding vialble M and N values the corresponding output
* frequency will be in the range:
* [target_freq_khz - tolerance_khz, target_freq_khz]
*
* Formula:
* Fdpll = (2 * M * Fref) / (N + 1)
*
* Considerations for lock-time:
* - Smaller the N, better lock-time, especially lock-time will be
* - For acceptable lock-times:
* Fref / (M + 1) >= 1 MHz
*
* Considerations for power:
* - The difference in power for different N values giving the same
* output is negligible. So, we optimize for lock-time
*
* Hard-constraints:
* - N can not be greater than 127(7 bit field for representing N)
*
* Usage:
* $ gcc clocks_get_m_n.c
* $ ./a.out
*/
int get_m_n_optimized(u32 target_freq_khz, u32 ref_freq_khz, u32 *M, u32 *N)
{
u32 freq = target_freq_khz;
u32 m_optimal, n_optimal, freq_optimal = 0, freq_old;
u32 m, n;
n = 1;
while (1) {
m = target_freq_khz / ref_freq_khz / 2 * n;
freq_old = 0;
while (1) {
freq = ref_freq_khz * 2 * m / n;
if (freq > target_freq_khz) {
freq = freq_old;
m--;
break;
}
m++;
freq_old = freq;
}
if (freq > freq_optimal) {
freq_optimal = freq;
m_optimal = m;
n_optimal = n;
}
n++;
if ((freq_optimal == target_freq_khz) ||
((ref_freq_khz / n) < 1000)) {
break;
}
}
n--;
*M = m_optimal;
*N = n_optimal - 1;
printf("ref %d m %d n %d target %d locked %d\n", ref_freq_khz,
m_optimal, n_optimal - 1, target_freq_khz, freq_optimal);
return 0;
}
void main(void)
{
u32 m, n;
printf("\nMPU - 2000000\n");
get_m_n_optimized(2000000, 12000, &m, &n);
get_m_n_optimized(2000000, 13000, &m, &n);
get_m_n_optimized(2000000, 16800, &m, &n);
get_m_n_optimized(2000000, 19200, &m, &n);
get_m_n_optimized(2000000, 26000, &m, &n);
get_m_n_optimized(2000000, 27000, &m, &n);
get_m_n_optimized(2000000, 38400, &m, &n);
printf("\nMPU - 1200000\n");
get_m_n_optimized(1200000, 12000, &m, &n);
get_m_n_optimized(1200000, 13000, &m, &n);
get_m_n_optimized(1200000, 16800, &m, &n);
get_m_n_optimized(1200000, 19200, &m, &n);
get_m_n_optimized(1200000, 26000, &m, &n);
get_m_n_optimized(1200000, 27000, &m, &n);
get_m_n_optimized(1200000, 38400, &m, &n);
printf("\nMPU - 1584000\n");
get_m_n_optimized(1584000, 12000, &m, &n);
get_m_n_optimized(1584000, 13000, &m, &n);
get_m_n_optimized(1584000, 16800, &m, &n);
get_m_n_optimized(1584000, 19200, &m, &n);
get_m_n_optimized(1584000, 26000, &m, &n);
get_m_n_optimized(1584000, 27000, &m, &n);
get_m_n_optimized(1584000, 38400, &m, &n);
printf("\nCore 1600000\n");
get_m_n_optimized(1600000, 12000, &m, &n);
get_m_n_optimized(1600000, 13000, &m, &n);
get_m_n_optimized(1600000, 16800, &m, &n);
get_m_n_optimized(1600000, 19200, &m, &n);
get_m_n_optimized(1600000, 26000, &m, &n);
get_m_n_optimized(1600000, 27000, &m, &n);
get_m_n_optimized(1600000, 38400, &m, &n);
printf("\nPER 1536000\n");
get_m_n_optimized(1536000, 12000, &m, &n);
get_m_n_optimized(1536000, 13000, &m, &n);
get_m_n_optimized(1536000, 16800, &m, &n);
get_m_n_optimized(1536000, 19200, &m, &n);
get_m_n_optimized(1536000, 26000, &m, &n);
get_m_n_optimized(1536000, 27000, &m, &n);
get_m_n_optimized(1536000, 38400, &m, &n);
printf("\nIVA 1862000\n");
get_m_n_optimized(1862000, 12000, &m, &n);
get_m_n_optimized(1862000, 13000, &m, &n);
get_m_n_optimized(1862000, 16800, &m, &n);
get_m_n_optimized(1862000, 19200, &m, &n);
get_m_n_optimized(1862000, 26000, &m, &n);
get_m_n_optimized(1862000, 27000, &m, &n);
get_m_n_optimized(1862000, 38400, &m, &n);
printf("\nIVA Nitro - 1290000\n");
get_m_n_optimized(1290000, 12000, &m, &n);
get_m_n_optimized(1290000, 13000, &m, &n);
get_m_n_optimized(1290000, 16800, &m, &n);
get_m_n_optimized(1290000, 19200, &m, &n);
get_m_n_optimized(1290000, 26000, &m, &n);
get_m_n_optimized(1290000, 27000, &m, &n);
get_m_n_optimized(1290000, 38400, &m, &n);
printf("\nABE 196608 sys clk\n");
get_m_n_optimized(196608, 12000, &m, &n);
get_m_n_optimized(196608, 13000, &m, &n);
get_m_n_optimized(196608, 16800, &m, &n);
get_m_n_optimized(196608, 19200, &m, &n);
get_m_n_optimized(196608, 26000, &m, &n);
get_m_n_optimized(196608, 27000, &m, &n);
get_m_n_optimized(196608, 38400, &m, &n);
printf("\nABE 196608 32K\n");
get_m_n_optimized(196608000/4, 32768, &m, &n);
printf("\nUSB 1920000\n");
get_m_n_optimized(1920000, 12000, &m, &n);
get_m_n_optimized(1920000, 13000, &m, &n);
get_m_n_optimized(1920000, 16800, &m, &n);
get_m_n_optimized(1920000, 19200, &m, &n);
get_m_n_optimized(1920000, 26000, &m, &n);
get_m_n_optimized(1920000, 27000, &m, &n);
get_m_n_optimized(1920000, 38400, &m, &n);
printf("\nCore ES1 1523712\n");
get_m_n_optimized(1524000, 12000, &m, &n);
get_m_n_optimized(1524000, 13000, &m, &n);
get_m_n_optimized(1524000, 16800, &m, &n);
get_m_n_optimized(1524000, 19200, &m, &n);
get_m_n_optimized(1524000, 26000, &m, &n);
get_m_n_optimized(1524000, 27000, &m, &n);
/* exact recommendation for SDPs */
get_m_n_optimized(1523712, 38400, &m, &n);
}