usb: ums: wait for usb cable connection before enter ums mode

Before this change ums mode can not be entered when device
was using the same usb port for usb/uart communication.
Switching USB cable from UART to USB always causes ums exit.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>

common/cmd_usb_mass_storage.c

@@ -42,6 +42,30 @@ int do_usb_mass_storage(cmd_tbl_t *cmdtp, int flag,
 
 	g_dnl_register("ums");
 
+	/* Timeout unit: seconds */
+	int cable_ready_timeout = UMS_CABLE_READY_TIMEOUT;
+
+	if (!usb_cable_connected()) {
+		puts("Please connect USB cable.\n");
+
+		while (!usb_cable_connected()) {
+			if (ctrlc()) {
+				puts("\rCTRL+C - Operation aborted.\n");
+				goto exit;
+			}
+			if (!cable_ready_timeout) {
+				puts("\rUSB cable not detected.\n" \
+				     "Command exit.\n");
+				goto exit;
+			}
+
+			printf("\rAuto exit in: %.2d s.", cable_ready_timeout);
+			mdelay(1000);
+			cable_ready_timeout--;
+		}
+		puts("\r\n");
+	}
+
 	while (1) {
 		usb_gadget_handle_interrupts();
 

include/usb_mass_storage.h

@@ -20,6 +20,9 @@
 #define UMS_NUM_SECTORS		0
 #endif
 
+/* Wait at maximum 60 seconds for cable connection */
+#define UMS_CABLE_READY_TIMEOUT	60
+
 struct ums {
 	int (*read_sector)(struct ums *ums_dev,
 			   ulong start, lbaint_t blkcnt, void *buf);