arm: K3: sysfw-loader: Allow loading SYSFW via Y-Modem

In order to allow booting TI K3 family SoCs via Y-Modem add support for
loading System Firmware by tapping into the associated SPL core loader
function.

In this context also make sure a console is available and if not go
ahead and activate the early console feature which allows bringing up
an alternate full console before the main console is activated. Such
an alternate console is typically setup in a way that the associated
UART can be fully initialized prior to SYSFW services being available.

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>

arch/arm/mach-k3/sysfw-loader.c

@@ -12,6 +12,9 @@
 #include <remoteproc.h>
 #include <linux/soc/ti/ti_sci_protocol.h>
 #include <asm/arch/sys_proto.h>
+#include "common.h"
+
+DECLARE_GLOBAL_DATA_PTR;
 
 /* Name of the FIT image nodes for SYSFW and its config data */
 #define SYSFW_FIRMWARE			"sysfw.bin"
@@ -214,6 +217,24 @@ void k3_sysfw_loader(void (*config_pm_done_callback)(void))
 				   0);
 #endif
 		break;
+#endif
+#if CONFIG_IS_ENABLED(YMODEM_SUPPORT)
+	case BOOT_DEVICE_UART:
+#ifdef CONFIG_K3_EARLY_CONS
+		/*
+		 * Establish a serial console if not yet available as required
+		 * for UART-based boot. For this use the early console feature
+		 * that allows setting up a UART for use before SYSFW has been
+		 * brought up. Note that the associated UART module's clocks
+		 * must have gotten enabled by the ROM bootcode which will be
+		 * the case when continuing to boot serially from the same
+		 * UART that the ROM loaded the initial bootloader from.
+		 */
+		if (!gd->have_console)
+			early_console_init();
+#endif
+		ret = spl_ymodem_load_image(&spl_image, &bootdev);
+		break;
 #endif
 	default:
 		panic("Loading SYSFW image from device %u not supported!\n",