#define AO_LPC_FCCO_MIN 156000000
+static void
+ao_clock_delay(void)
+{
+ uint32_t i;
+ for (i = 0; i < 200; i++)
+ ao_arch_nop();
+}
+
void
ao_clock_init(void)
{
/* Turn the IRC clock back on */
lpc_scb.pdruncfg &= ~(1 << LPC_SCB_PDRUNCFG_IRC_PD);
+ ao_clock_delay();
/* Switch to the IRC clock */
lpc_scb.mainclksel = LPC_SCB_MAINCLKSEL_SEL_IRC << LPC_SCB_MAINCLKSEL_SEL;
+ lpc_scb.mainclkuen = (1 << LPC_SCB_MAINCLKUEN_ENA);
lpc_scb.mainclkuen = (0 << LPC_SCB_MAINCLKUEN_ENA);
lpc_scb.mainclkuen = (1 << LPC_SCB_MAINCLKUEN_ENA);
+ while (!(lpc_scb.mainclkuen & (1 << LPC_SCB_MAINCLKUEN_ENA)))
+ ;
/* Find a PLL post divider ratio that gets the FCCO in range */
for (p = 0; p < 4; p++)
/* Power down the PLL before touching the registers */
lpc_scb.pdruncfg |= (1 << LPC_SCB_PDRUNCFG_SYSPLL_PD);
+ ao_clock_delay();
/* Set PLL divider values */
lpc_scb.syspllctrl = ((AO_LPC_M << LPC_SCB_SYSPLLCTRL_MSEL) |
(p << LPC_SCB_SYSPLLCTRL_PSEL));
-
/* Turn off the external crystal clock */
lpc_scb.pdruncfg |= (1 << LPC_SCB_PDRUNCFG_SYSOSC_PD);
+ ao_clock_delay();
/* Configure the crystal clock */
lpc_scb.sysoscctrl = ((0 << LPC_SCB_SYSOSCCTRL_BYPASS) | /* using a crystal */
/* Turn on the external crystal clock */
lpc_scb.pdruncfg &= ~(1 << LPC_SCB_PDRUNCFG_SYSOSC_PD);
+ ao_clock_delay();
/* Select crystal as PLL input */
lpc_scb.syspllclksel = (LPC_SCB_SYSPLLCLKSEL_SEL_SYSOSC << LPC_SCB_SYSPLLCLKSEL_SEL);
- lpc_scb.syspllclkuen = 0;
lpc_scb.syspllclkuen = (1 << LPC_SCB_SYSPLLCLKUEN_ENA);
+ lpc_scb.syspllclkuen = (0 << LPC_SCB_SYSPLLCLKUEN_ENA);
+ lpc_scb.syspllclkuen = (1 << LPC_SCB_SYSPLLCLKUEN_ENA);
+ while (!(lpc_scb.syspllclkuen & (1 << LPC_SCB_SYSPLLCLKUEN_ENA)))
+ ;
/* Turn on the PLL */
lpc_scb.pdruncfg &= ~(1 << LPC_SCB_PDRUNCFG_SYSPLL_PD);
/* Switch to the PLL */
lpc_scb.mainclksel = LPC_SCB_MAINCLKSEL_SEL_PLL_OUTPUT << LPC_SCB_MAINCLKSEL_SEL;
- lpc_scb.mainclkuen = 0 << LPC_SCB_MAINCLKUEN_ENA;
- lpc_scb.mainclkuen = 1 << LPC_SCB_MAINCLKUEN_ENA;
+ lpc_scb.mainclkuen = (1 << LPC_SCB_MAINCLKUEN_ENA);
+ lpc_scb.mainclkuen = (0 << LPC_SCB_MAINCLKUEN_ENA);
+ lpc_scb.mainclkuen = (1 << LPC_SCB_MAINCLKUEN_ENA);
+ while (!(lpc_scb.mainclkuen & (1 << LPC_SCB_MAINCLKUEN_ENA)))
+ ;
/* Set system clock divider */
lpc_scb.sysahbclkdiv = AO_LPC_CLKOUT / AO_LPC_SYSCLK;
- /* Set USB clock source */
- lpc_scb.usbclksel = (LPC_SCB_USBCLKSEL_SEL_MAIN_CLOCK << LPC_SCB_USBCLKSEL_SEL);
- lpc_scb.usbclkuen = (0 << LPC_SCB_USBCLKUEN_ENA);
- lpc_scb.usbclkuen = (1 << LPC_SCB_USBCLKUEN_ENA);
-
/* Shut down perhipheral clocks (enabled as needed) */
lpc_scb.ssp0clkdiv = 0;
lpc_scb.uartclkdiv = 0;