nextpnr/himbaechel/uarch/gatemate/pll.cc

353 lines
14 KiB
C++

/*
* nextpnr -- Next Generation Place and Route
*
* Copyright (C) 2024 The Project Peppercorn Authors.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include <boost/algorithm/string.hpp>
#include "pack.h"
#define HIMBAECHEL_CONSTIDS "uarch/gatemate/constids.inc"
#include "himbaechel_constids.h"
namespace {
USING_NEXTPNR_NAMESPACE;
double calculate_delta_stepsize(double num)
{
std::ostringstream out;
out << std::fixed << std::setprecision(4) << num;
std::string str = out.str();
switch (4 - (str.size() - str.find_last_not_of('0') - 1)) {
case 4:
return 0.0001;
case 3:
return 0.001;
case 2:
return 0.01;
case 1:
return 0.1;
default:
return 1.0;
}
}
int getDCO_optimized_value(int f_dco_min, int f_dco_max, double f_dco)
{
/*
optimization parameters
DCO_OPT:
1: Optimized to lower DCO frequency.
2: Optimized to the middle of the DCO range (DEFAULT)
3: Optimized to upper DCO frequency.
*/
const int DCO_OPT = 2; // 1: to lower DCO, 2: to DCO middle range, 3: to upper DCO, default = 2
const int DCO_FREQ_OPT_FACTOR = 24; // proportional factor btw. frequency match and dco optimization
switch (DCO_OPT) {
case 1:
return round(abs(f_dco - f_dco_min)) * DCO_FREQ_OPT_FACTOR;
case 3:
return round(abs(f_dco - f_dco_max)) * DCO_FREQ_OPT_FACTOR;
default: {
int f_dco_middle = (f_dco_max + f_dco_min) / 2; // Middle of DCO Range in MHz
return round(abs(f_dco - f_dco_middle)) * DCO_FREQ_OPT_FACTOR;
}
}
}
void get_M1_M2(double f_core, double f_core_delta, PllCfgRecord &setting, double max_input_freq)
{
// precise output frequency preference, highest priority
// the larger value the higher priority
const int OUT_FREQ_OPT_FACTOR = 4200000;
std::vector<PllCfgRecord> res_arr;
for (int M1 = 1; M1 <= 64; M1++) {
for (int M2 = 1; M2 <= 1024; M2++) {
if (((M1 * M2) % 2) != 0) {
// M1*M2-->even number(except one);
// this is important to ensure 90 degree phase shifting of clock output
if (M1 * M2 != 1)
continue;
}
double f_core_local = setting.f_dco / (2 * setting.PDIV1 * M1 * M2);
if (f_core_local > max_input_freq / 4)
continue; // f_core max limit
if ((f_core_local - f_core) < -f_core_delta)
break; // lower limit jump to parent loop
if (abs(f_core_local - f_core) > f_core_delta)
continue; // reg limit continue
if (setting.f_dco / setting.PDIV1 > max_input_freq)
continue; // M1 input freq limit
if ((setting.f_dco / setting.PDIV1) / M1 > max_input_freq / 2)
continue; // M2 input freq limit
PllCfgRecord tmp;
tmp.f_core = f_core_local;
tmp.M1 = M1;
tmp.M2 = M2;
tmp.weight = abs(f_core_local - f_core) * OUT_FREQ_OPT_FACTOR;
res_arr.push_back(tmp);
// frequency match
if (abs(f_core_local - f_core) <= f_core_delta) {
auto it = std::min_element(
res_arr.begin(), res_arr.end(),
[](const PllCfgRecord &a, const PllCfgRecord &b) { return a.weight < b.weight; });
size_t index = std::distance(res_arr.begin(), it);
setting.M1 = res_arr[index].M1;
setting.M2 = res_arr[index].M2;
setting.f_core = res_arr[index].f_core;
setting.f_core_delta = abs(res_arr[index].f_core - f_core);
setting.core_weight = res_arr[index].weight + setting.M1 + setting.M2 + setting.N1 + setting.N2 +
setting.K + setting.PDIV1;
return;
}
}
}
}
void get_DCO_ext_feedback(double f_core, double f_ref, PllCfgRecord &setting, int f_dco_min, int f_dco_max,
double f_dco, double max_input_freq)
{
std::vector<PllCfgRecord> res_arr;
for (int M1 = 1; M1 <= 64; M1++) {
for (int M2 = 1; M2 <= 1024; M2++) {
if (((M1 * M2) % 2) != 0) {
// M1*M2-->even number(except one);
// this is important to ensure 90 degree phase shifting of clock output
if (M1 * M2 != 1)
continue;
}
double f_dco_local = (f_ref / setting.K) * 2 * setting.PDIV1 * setting.N1 * setting.N2 * M1 * M2;
if (f_dco_local > f_dco_max)
break; // upper limit
if ((f_dco_local < f_dco_min) || (f_dco_local > f_dco_max))
continue; // dco out of range limit
if (f_dco_local / setting.PDIV1 > max_input_freq)
continue; // M1 input freq limit
if ((f_dco_local / setting.PDIV1) / M1 > max_input_freq / 2)
continue; // M2 input freq limit
PllCfgRecord tmp;
tmp.f_dco = f_dco_local;
tmp.M1 = M1;
tmp.M2 = M2;
tmp.weight = f_dco_local + getDCO_optimized_value(f_dco_min, f_dco_max, f_dco_local);
res_arr.push_back(tmp);
}
}
auto it = std::min_element(res_arr.begin(), res_arr.end(),
[](const PllCfgRecord &a, const PllCfgRecord &b) { return a.weight < b.weight; });
size_t index = std::distance(res_arr.begin(), it);
setting.M1 = res_arr[index].M1;
setting.M2 = res_arr[index].M2;
setting.f_dco = res_arr[index].f_dco;
}
}; // namespace
NEXTPNR_NAMESPACE_BEGIN
PllCfgRecord GateMatePacker::get_pll_settings(double f_ref, double f_core, int mode, int low_jitter, bool pdiv0_mux,
bool feedback)
{
const int MATCH_LIMIT = 10; // only for low jitter = false
// frequency tolerance for low jitter = false, the maximum frequency deviation in MHz from f_core
const double DELTA_LIMIT = 0.1;
double max_input_freq;
int f_dco_min, f_dco_max, pdiv1_min;
double f_dco;
std::vector<PllCfgRecord> pll_cfg_arr;
PllCfgRecord pll_cfg_rec;
switch (mode) {
case 1: {
// low power
f_dco_min = 500;
f_dco_max = 1000;
pdiv1_min = 1;
max_input_freq = 1000;
break;
}
case 2: {
// economy
f_dco_min = 1000;
f_dco_max = 2000;
pdiv1_min = 2;
max_input_freq = 1250;
break;
}
default: {
// initialize as speed
f_dco_min = 1250;
f_dco_max = 2500;
pdiv1_min = 2;
max_input_freq = 1666.67;
break;
}
}
double f_core_par = f_core;
if (f_ref > 50)
log_warning("The PLL input frequency is outside the specified frequency (max 50 MHz ) range\n");
if (pdiv0_mux && feedback) {
double res;
if (modf(f_core / f_ref, &res) != 0)
log_warning("In this PLL mode f_core can only be greater and multiple of f_ref\n");
}
if (pdiv0_mux) {
if (f_core > max_input_freq / 4) {
f_core = max_input_freq / 4;
log_warning("Frequency out of range; PLL max output frequency for mode: %d: %.5f MHz\n", mode,
max_input_freq / 4);
}
}
pll_cfg_rec.K = 1;
pll_cfg_rec.N1 = 1;
pll_cfg_rec.N2 = 1;
pll_cfg_rec.M1 = 1;
pll_cfg_rec.M2 = 1;
pll_cfg_rec.PDIV1 = 2;
pll_cfg_rec.f_dco = 0;
pll_cfg_rec.f_core_delta = std::numeric_limits<double>::max();
pll_cfg_rec.f_core = pll_cfg_rec.f_dco / (2 * pll_cfg_rec.PDIV1);
pll_cfg_rec.core_weight = std::numeric_limits<double>::max();
pll_cfg_arr.push_back(pll_cfg_rec);
double f_core_delta_stepsize = calculate_delta_stepsize(f_core);
int K = 1;
int K_max = low_jitter ? 1 : 1024;
int match_cnt = 0;
int match_delta_cnt = 0;
while (K <= K_max) {
for (int N1 = 1; N1 <= 64; N1++) {
for (int N2 = 1; N2 <= 1024; N2++) {
for (int PDIV1 = pdiv1_min; PDIV1 <= 2; PDIV1++) {
if (feedback) {
// extern feedback
int f_core_local = (f_ref / K) * N1 * N2;
if (f_core_local > max_input_freq / 4)
continue;
if (abs(f_core - f_core_local) < pll_cfg_arr[0].f_core_delta) {
// search for best frequency match
pll_cfg_arr[0].f_core = f_core_local;
pll_cfg_arr[0].f_core_delta = abs(f_core - f_core_local);
pll_cfg_arr[0].K = K;
pll_cfg_arr[0].N1 = N1;
pll_cfg_arr[0].N2 = N2;
pll_cfg_arr[0].PDIV1 = PDIV1;
}
if (pll_cfg_arr[0].f_core_delta == 0) {
get_DCO_ext_feedback(f_core, f_ref, pll_cfg_arr[0], f_dco_min, f_dco_max, f_dco,
max_input_freq);
log_info(" PLL fout= %.4f MHz (fout error %.5f%% of requested %.4f MHz)\n",
pll_cfg_arr[0].f_core,
100 - (100 * std::min(pll_cfg_arr[0].f_core, f_core_par) /
std::max(pll_cfg_arr[0].f_core, f_core_par)),
f_core);
return pll_cfg_arr[0];
}
} else {
f_dco = (f_ref / K) * PDIV1 * N1 * N2;
if ((f_dco <= f_dco_min) || (f_dco > f_dco_max))
continue; // DCO out of range
if (f_dco == 0)
continue; // DCO = 0
if (f_dco / PDIV1 > max_input_freq)
continue; // N1 input freq limit
if ((f_dco / PDIV1) / N1 > max_input_freq / 2)
continue; // N2 input freq limit
if (int(f_core) > int(f_dco / (2 * PDIV1)))
continue; // > f_core max
pll_cfg_rec.f_core = 0;
pll_cfg_rec.f_dco = f_dco;
pll_cfg_rec.f_core_delta = std::numeric_limits<double>::max();
pll_cfg_rec.K = K;
pll_cfg_rec.N1 = N1;
pll_cfg_rec.N2 = N2;
pll_cfg_rec.PDIV1 = PDIV1;
pll_cfg_rec.M1 = 0;
pll_cfg_rec.M2 = 0;
pll_cfg_rec.core_weight = std::numeric_limits<double>::max();
if (!pdiv0_mux) {
// f_core = f_dco/2
pll_cfg_rec.M1 = 1;
pll_cfg_rec.M2 = 1;
pll_cfg_rec.f_core = pll_cfg_rec.f_dco / 2;
pll_cfg_rec.core_weight = abs(pll_cfg_rec.f_core - f_core);
} else {
// default clock path
// calculate M1, M2 then calculate weight for intern loop feedback
bool found = false;
double f_core_delta = 0;
while (f_core_delta < (round((max_input_freq / 4) - f_ref / K))) {
get_M1_M2(f_core, f_core_delta, pll_cfg_rec, max_input_freq);
if (pll_cfg_rec.f_core != 0 && pll_cfg_rec.f_core_delta <= f_core_delta) {
// best result
pll_cfg_rec.core_weight +=
pll_cfg_rec.f_dco + getDCO_optimized_value(f_dco_min, f_dco_max, f_dco);
found = true;
}
if (found)
break; // best result found
f_core_delta += f_core_delta_stepsize;
}
}
pll_cfg_arr.push_back(pll_cfg_rec);
if (pll_cfg_rec.f_core_delta == 0)
match_cnt++;
if (pll_cfg_rec.f_core_delta < DELTA_LIMIT)
match_delta_cnt++;
}
}
}
}
K++;
// only with low_jitter false
if (match_cnt > MATCH_LIMIT)
break;
if ((match_cnt == 0) && (match_delta_cnt > MATCH_LIMIT))
break;
}
if (feedback) {
// extern feedback if not exact match pick the best here
get_DCO_ext_feedback(f_core, f_ref, pll_cfg_arr[0], f_dco_min, f_dco_max, f_dco, max_input_freq);
}
auto it =
std::min_element(pll_cfg_arr.begin(), pll_cfg_arr.end(), [](const PllCfgRecord &a, const PllCfgRecord &b) {
return a.core_weight < b.core_weight;
});
PllCfgRecord val = pll_cfg_arr.at(std::distance(pll_cfg_arr.begin(), it));
log_info(" PLL fout= %.4f MHz (fout error %.5f%% of requested %.4f MHz)\n", val.f_core,
100 - (100 * std::min(val.f_core, f_core_par) / std::max(val.f_core, f_core_par)), f_core);
return val;
}
NEXTPNR_NAMESPACE_END