soc: ambiq: enable the TPIU clock source

This commit enables the TPIU clock source in Apollo3 and
Apollo4 soc initialization if LOG_BACKEND_SWO is used.

Signed-off-by: Aaron Ye <[email protected]>

Author: aaronyegx

soc/ambiq/apollo3x/soc.c

@@ -28,4 +28,10 @@ void soc_early_init_hook(void)
 #ifdef CONFIG_PM
 	ambiq_power_init();
 #endif
+
+#ifdef CONFIG_LOG_BACKEND_SWO
+	/* Select HFRC/8 (6MHz) for the TPIU clock source */
+	MCUCTRL->TPIUCTRL_b.CLKSEL = MCUCTRL_TPIUCTRL_CLKSEL_HFRCDIV8;
+	MCUCTRL->TPIUCTRL_b.ENABLE = MCUCTRL_TPIUCTRL_ENABLE_EN;
+#endif
 }

soc/ambiq/apollo4x/soc.c

@@ -23,4 +23,10 @@ void soc_early_init_hook(void)
 #ifdef CONFIG_PM
 	ambiq_power_init();
 #endif
+
+#ifdef CONFIG_LOG_BACKEND_SWO
+	/* Select HFRC 48MHz for the TPIU clock source */
+	MCUCTRL->DBGCTRL_b.CM4CLKSEL = MCUCTRL_DBGCTRL_CM4CLKSEL_HFRC48;
+	MCUCTRL->DBGCTRL_b.CM4TPIUENABLE = MCUCTRL_DBGCTRL_CM4TPIUENABLE_EN;
+#endif
 }