arm: K3: common: Allow for early console functionality

Implement an early console functionality in SPL that can be used before
the main console is being brought up. This helps in situations where the
main console is dependent on System Firmware (SYSFW) being up and running,
which is usually not the case during the very early stages of boot. Using
this early console functionality will allow for an alternate serial port
to be used to support things like UART-based boot and early diagnostic
messages until the main console is ready to get activated.

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
diff --git a/arch/arm/mach-k3/common.c b/arch/arm/mach-k3/common.c
index c16afc6..6c453b9 100644
--- a/arch/arm/mach-k3/common.c
+++ b/arch/arm/mach-k3/common.c
@@ -27,6 +27,32 @@
 	return (struct ti_sci_handle *)ti_sci_get_handle_from_sysfw(dev);
 }
 
+DECLARE_GLOBAL_DATA_PTR;
+
+#ifdef CONFIG_K3_EARLY_CONS
+int early_console_init(void)
+{
+	struct udevice *dev;
+	int ret;
+
+	gd->baudrate = CONFIG_BAUDRATE;
+
+	ret = uclass_get_device_by_seq(UCLASS_SERIAL, CONFIG_K3_EARLY_CONS_IDX,
+				       &dev);
+	if (ret) {
+		printf("Error getting serial dev for early console! (%d)\n",
+		       ret);
+		return ret;
+	}
+
+	gd->cur_serial_dev = dev;
+	gd->flags |= GD_FLG_SERIAL_READY;
+	gd->have_console = 1;
+
+	return 0;
+}
+#endif
+
 #ifdef CONFIG_SYS_K3_SPL_ATF
 void __noreturn jump_to_image_no_args(struct spl_image_info *spl_image)
 {