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efm32: cmu: support switching HFCLK to USHFRCODIV2

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Allow for the high frequency clock that controlls things such as the
main CPU to be switched over to USHFRCODIV2.  This is a 24 MHz PLL
that is trimmed using clock recovery from the USB signal, and is
accurate to within 1% of 24 MHz.

Signed-off-by: Sean Cross <sean@xobs.io>
This commit is contained in:
Sean Cross 2018-05-10 14:59:50 -07:00 committed by Karl Palsson
parent 065e0412ec
commit b805db0444
1 changed files with 17 additions and 0 deletions
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17
lib/efm32/hg/cmu.c
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@ -105,6 +105,9 @@ void cmu_osc_on(enum cmu_osc osc)
case AUXHFRCO: case AUXHFRCO:
CMU_OSCENCMD = CMU_OSCENCMD_AUXHFRCOEN; CMU_OSCENCMD = CMU_OSCENCMD_AUXHFRCOEN;
break; break;
default:
/* not applicable */
break;
} }
} }
@ -133,6 +136,9 @@ void cmu_osc_off(enum cmu_osc osc)
case AUXHFRCO: case AUXHFRCO:
CMU_OSCENCMD = CMU_OSCENCMD_AUXHFRCODIS; CMU_OSCENCMD = CMU_OSCENCMD_AUXHFRCODIS;
break; break;
default:
/* not applicable */
break;
} }
} }
@ -163,6 +169,9 @@ bool cmu_osc_ready_flag(enum cmu_osc osc)
case AUXHFRCO: case AUXHFRCO:
return (CMU_STATUS & CMU_STATUS_AUXHFRCORDY) != 0; return (CMU_STATUS & CMU_STATUS_AUXHFRCORDY) != 0;
break; break;
default:
/* not applicable */
break;
} }
return false; return false;
@ -193,6 +202,9 @@ void cmu_wait_for_osc_ready(enum cmu_osc osc)
case AUXHFRCO: case AUXHFRCO:
while ((CMU_STATUS & CMU_STATUS_AUXHFRCORDY) == 0); while ((CMU_STATUS & CMU_STATUS_AUXHFRCORDY) == 0);
break; break;
default:
/* not applicable */
break;
} }
} }
@ -218,6 +230,9 @@ void cmu_set_hfclk_source(enum cmu_osc osc)
case LFRCO: case LFRCO:
CMU_CMD = CMU_CMD_HFCLKSEL_LFRCO; CMU_CMD = CMU_CMD_HFCLKSEL_LFRCO;
break; break;
case USHFRCODIV2:
CMU_CMD = CMU_CMD_HFCLKSEL_USHFRCODIV2;
break;
default: default:
/* not applicable */ /* not applicable */
return; return;
@ -239,6 +254,8 @@ enum cmu_osc cmu_get_hfclk_source(void)
return HFXO; return HFXO;
} else if (status & CMU_STATUS_HFRCOSEL) { } else if (status & CMU_STATUS_HFRCOSEL) {
return HFRCO; return HFRCO;
} else if (status & CMU_STATUS_USHFRCODIV2SEL) {
return USHFRCODIV2;
} }
/* never reached */ /* never reached */