soc: arm: nxp_imx: r5xx: add Kconfig to clock FC0 from FRO

Flexcomm0 has option to clock from FRO.

Signed-off-by: Derek Snell <[email protected]>

Author: DerekSnell

soc/arm/nxp_imx/rt5xx/Kconfig.soc

@@ -1,6 +1,6 @@
 # i.MX RT5XX Series
 
-# Copyright (c) 2022, NXP
+# Copyright 2022-2023, NXP
 # SPDX-License-Identifier: Apache-2.0
 
 choice
@@ -129,4 +129,16 @@ config IMXRT5XX_CODE_CACHE
 	  Enable code cache for FlexSPI region at boot. If this Kconfig is
 	  cleared, the CACHE64 controller will be disabled during SOC init
 
+choice FLEXCOMM0_CLK_SRC
+	prompt "Clock source for Flexcomm0"
+	default FLEXCOMM0_CLK_SRC_FRG
+
+config FLEXCOMM0_CLK_SRC_FRG
+	bool "FRG is source of Flexcomm0 clock"
+
+config FLEXCOMM0_CLK_SRC_FRO
+	bool "FRO_DIV4 is source of Flexcomm0 clock"
+
+endchoice
+
 endif # SOC_SERIES_IMX_RT5XX

soc/arm/nxp_imx/rt5xx/soc.c

@@ -281,8 +281,12 @@ void __weak rt5xx_clock_init(void)
 	/* Switch SYSTICK_CLK to MAIN_CLK_DIV */
 	CLOCK_AttachClk(kMAIN_CLK_DIV_to_SYSTICK_CLK);
 #if DT_NODE_HAS_COMPAT_STATUS(DT_NODELABEL(flexcomm0), nxp_lpc_usart, okay)
-	/* Switch FLEXCOMM0 to FRG */
-	CLOCK_AttachClk(kFRG_to_FLEXCOMM0);
+	#ifdef CONFIG_FLEXCOMM0_CLK_SRC_FRG
+		/* Switch FLEXCOMM0 to FRG */
+		CLOCK_AttachClk(kFRG_to_FLEXCOMM0);
+	#elif defined(CONFIG_FLEXCOMM0_CLK_SRC_FRO)
+		CLOCK_AttachClk(kFRO_DIV4_to_FLEXCOMM0);
+	#endif
 #endif
 #if CONFIG_USB_DC_NXP_LPCIP3511
 	usb_device_clock_init();