static void use_hfrosc(int div, int trim)
{
// Make sure the HFROSC is running at its default setting
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
select_clock(const clock_config_t *cfg)
{
uint32_t new_qspi_div = 0;
uint32_t old_qspi_div = SPI0_REG(SPI_REG_SCKDIV);
/* Clock based on external escilator */
if (!cfg->xosc || cfg->pll) {
/* Turn on internal oscillator */
PRCI_REG(PRCI_HFROSCCFG) = ROSC_DIV(cfg->osc_div) |
ROSC_TRIM(MYNEWT_VAL(HFROSC_DEFAULT_TRIM_VAL)) |
ROSC_EN(1);
while ((PRCI_REG(PRCI_HFROSCCFG) & ROSC_RDY(1)) == 0) {
}
/* Compute CPU frequency on demand */
cpu_freq = 0;
}
if (cfg->xosc) {
/* Turn on external oscillator if not ready yet */
if ((PRCI_REG(PRCI_HFXOSCCFG) & XOSC_RDY(1)) == 0) {
PRCI_REG(PRCI_HFXOSCCFG) = XOSC_EN(1);
while ((PRCI_REG(PRCI_HFXOSCCFG) & XOSC_RDY(1)) == 0) {
}
}
cpu_freq = cfg->frq;
}
/*
* If reqested closk is higher then FLASH_MAX_CLOCK change divider so QSPI
* clock is in rage.
*/
if (cfg->frq >= MYNEWT_VAL(FLASH_MAX_CLOCK) * 2) {
new_qspi_div = (cfg->frq + MYNEWT_VAL(FLASH_MAX_CLOCK) - 1) / (2 * MYNEWT_VAL(FLASH_MAX_CLOCK)) - 1;
}
/* New qspi divider is higher, reduce qspi clock before switching to higher clock */
if (new_qspi_div > old_qspi_div) {
SPI0_REG(SPI_REG_SCKDIV) = new_qspi_div;
}
PRCI_REG(PRCI_PLLDIV) = PLL_FINAL_DIV_BY_1(cfg->pll_outdiv1) |
PLL_FINAL_DIV(cfg->pll_out_div);
if (cfg->pll) {
uint32_t now;
uint32_t pllcfg = PLL_REFSEL(cfg->xosc) |
PLL_R(cfg->pll_div_r) | PLL_F(cfg->pll_mul_f) | PLL_Q(cfg->pll_div_q);
PRCI_REG(PRCI_PLLCFG) = PLL_BYPASS(1) | pllcfg;
PRCI_REG(PRCI_PLLCFG) ^= PLL_BYPASS(1);
/* 100us lock grace period */
now = mtime_lo();
while (mtime_lo() - now < 4) {
}
/* Now it is safe to check for PLL Lock */
while ((PRCI_REG(PRCI_PLLCFG) & PLL_LOCK(1)) == 0) {
}
/* Select PLL as clock source */
PRCI_REG(PRCI_PLLCFG) |= PLL_SEL(1) | pllcfg;
} else {
/* Select bypassed PLL as source signal, it allows to use HFXOSC */
PRCI_REG(PRCI_PLLCFG) = PLL_BYPASS(1) | PLL_REFSEL(cfg->xosc) | PLL_SEL(1);
}
/*
* Old qspi divider was higher, now it's safe to reduce divider, increasing
* qspi clock for better performance
*/
if (new_qspi_div < old_qspi_div) {
SPI0_REG(SPI_REG_SCKDIV) = new_qspi_div;
}
}
