Firmwares/fpga_spn/bsp/drivers/fe300prci/fe300prci_driver.c

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// See LICENSE file for license details
#include "platform.h"
#ifdef PRCI_CTRL_ADDR
#include "fe300prci/fe300prci_driver.h"
#include <unistd.h>
#define rdmcycle(x) { \
uint32_t lo, hi, hi2; \
__asm__ __volatile__ ("1:\n\t" \
"csrr %0, mcycleh\n\t" \
"csrr %1, mcycle\n\t" \
"csrr %2, mcycleh\n\t" \
"bne %0, %2, 1b\n\t" \
: "=r" (hi), "=r" (lo), "=r" (hi2)) ; \
*(x) = lo | ((uint64_t) hi << 32); \
}
uint32_t PRCI_measure_mcycle_freq(uint32_t mtime_ticks, uint32_t mtime_freq)
{
uint32_t start_mtime = CLINT_REG(CLINT_MTIME);
uint32_t end_mtime = start_mtime + mtime_ticks + 1;
// Make sure we won't get rollover.
while (end_mtime < start_mtime){
start_mtime = CLINT_REG(CLINT_MTIME);
end_mtime = start_mtime + mtime_ticks + 1;
}
// Don't start measuring until mtime edge.
uint32_t tmp = start_mtime;
do {
start_mtime = CLINT_REG(CLINT_MTIME);
} while (start_mtime == tmp);
uint64_t start_mcycle;
rdmcycle(&start_mcycle);
while (CLINT_REG(CLINT_MTIME) < end_mtime) ;
uint64_t end_mcycle;
rdmcycle(&end_mcycle);
uint32_t difference = (uint32_t) (end_mcycle - start_mcycle);
uint64_t freq = ((uint64_t) difference * mtime_freq) / mtime_ticks;
return (uint32_t) freq & 0xFFFFFFFF;
}
void PRCI_use_hfrosc(int div, int trim)
{
// Make sure the HFROSC is running at its default setting
// It is OK to change this even if we are running off of it.
PRCI_REG(PRCI_HFROSCCFG) = (ROSC_DIV(div) | ROSC_TRIM(trim) | ROSC_EN(1));
while ((PRCI_REG(PRCI_HFROSCCFG) & ROSC_RDY(1)) == 0);
PRCI_REG(PRCI_PLLCFG) &= ~PLL_SEL(1);
}
void PRCI_use_pll(int refsel, int bypass,
int r, int f, int q, int finaldiv,
int hfroscdiv, int hfrosctrim)
{
// Ensure that we aren't running off the PLL before we mess with it.
if (PRCI_REG(PRCI_PLLCFG) & PLL_SEL(1)) {
// Make sure the HFROSC is running at its default setting
PRCI_use_hfrosc(4, 16);
}
// Set PLL Source to be HFXOSC if desired.
uint32_t config_value = 0;
config_value |= PLL_REFSEL(refsel);
if (bypass) {
// Bypass
config_value |= PLL_BYPASS(1);
PRCI_REG(PRCI_PLLCFG) = config_value;
// If we don't have an HFXTAL, this doesn't really matter.
// Set our Final output divide to divide-by-1:
PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV_BY_1(1) | PLL_FINAL_DIV(0));
} else {
// To overclock, use the hfrosc
if (hfrosctrim >= 0 && hfroscdiv >= 0) {
PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
}
// Set DIV Settings for PLL
// (Legal values of f_REF are 6-48MHz)
// Set DIVR to divide-by-2 to get 8MHz frequency
// (legal values of f_R are 6-12 MHz)
config_value |= PLL_BYPASS(1);
config_value |= PLL_R(r);
// Set DIVF to get 512Mhz frequncy
// There is an implied multiply-by-2, 16Mhz.
// So need to write 32-1
// (legal values of f_F are 384-768 MHz)
config_value |= PLL_F(f);
// Set DIVQ to divide-by-2 to get 256 MHz frequency
// (legal values of f_Q are 50-400Mhz)
config_value |= PLL_Q(q);
// Set our Final output divide to divide-by-1:
if (finaldiv == 1){
PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV_BY_1(1) | PLL_FINAL_DIV(0));
} else {
PRCI_REG(PRCI_PLLDIV) = (PLL_FINAL_DIV(finaldiv-1));
}
PRCI_REG(PRCI_PLLCFG) = config_value;
// Un-Bypass the PLL.
PRCI_REG(PRCI_PLLCFG) &= ~PLL_BYPASS(1);
// Wait for PLL Lock
// Note that the Lock signal can be glitchy.
// Need to wait 100 us
// RTC is running at 32kHz.
// So wait 4 ticks of RTC.
uint32_t now = CLINT_REG(CLINT_MTIME);
while (CLINT_REG(CLINT_MTIME) - now < 4) ;
// Now it is safe to check for PLL Lock
while ((PRCI_REG(PRCI_PLLCFG) & PLL_LOCK(1)) == 0);
}
// Switch over to PLL Clock source
PRCI_REG(PRCI_PLLCFG) |= PLL_SEL(1);
// If we're running off HFXOSC, turn off the HFROSC to
// save power.
if (refsel) {
PRCI_REG(PRCI_HFROSCCFG) &= ~ROSC_EN(1);
}
}
void PRCI_use_default_clocks()
{
// Turn off the LFROSC
AON_REG(AON_LFROSC) &= ~ROSC_EN(1);
// Use HFROSC
PRCI_use_hfrosc(4, 16);
}
void PRCI_use_hfxosc(uint32_t finaldiv)
{
PRCI_use_pll(1, // Use HFXTAL
1, // Bypass = 1
0, // PLL settings don't matter
0, // PLL settings don't matter
0, // PLL settings don't matter
finaldiv,
-1,
-1);
}
// This is a generic function, which
// doesn't span the entire range of HFROSC settings.
// It only adjusts the trim, which can span a hundred MHz or so.
// This function does not check the legality of the PLL settings
// at all, and it is quite possible to configure invalid PLL settings
// this way.
// It returns the actual measured CPU frequency.
uint32_t PRCI_set_hfrosctrim_for_f_cpu(uint32_t f_cpu, PRCI_freq_target target )
{
uint32_t hfrosctrim = 0;
uint32_t hfroscdiv = 4;
uint32_t prev_trim = 0;
// In this function we use PLL settings which
// will give us a 32x multiplier from the output
// of the HFROSC source to the output of the
// PLL. We first measure our HFROSC to get the
// right trim, then finally use it as the PLL source.
// We should really check here that the f_cpu
// requested is something in the limit of the PLL. For
// now that is up to the user.
// This will undershoot for frequencies not divisible by 16.
uint32_t desired_hfrosc_freq = (f_cpu/ 16);
PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
// Ignore the first run (for icache reasons)
uint32_t cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
uint32_t prev_freq = cpu_freq;
while ((cpu_freq < desired_hfrosc_freq) && (hfrosctrim < 0x1F)){
prev_trim = hfrosctrim;
prev_freq = cpu_freq;
hfrosctrim ++;
PRCI_use_hfrosc(hfroscdiv, hfrosctrim);
cpu_freq = PRCI_measure_mcycle_freq(3000, RTC_FREQ);
}
// We couldn't go low enough
if (prev_freq > desired_hfrosc_freq){
PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ);
return cpu_freq;
}
// We couldn't go high enough
if (cpu_freq < desired_hfrosc_freq){
PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ);
return cpu_freq;
}
// Check for over/undershoot
switch(target) {
case(PRCI_FREQ_CLOSEST):
if ((desired_hfrosc_freq - prev_freq) < (cpu_freq - desired_hfrosc_freq)) {
PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
} else {
PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, hfrosctrim);
}
break;
case(PRCI_FREQ_UNDERSHOOT):
PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, prev_trim);
break;
default:
PRCI_use_pll(0, 0, 1, 31, 1, 1, hfroscdiv, hfrosctrim);
}
cpu_freq = PRCI_measure_mcycle_freq(1000, RTC_FREQ);
return cpu_freq;
}
#endif