usb: ums: add ums exit feature by ctrl+c or by detach usb cable

This patch allows exiting from UMS mode to u-boot prompt
by detaching usb cable or by pressing ctrl+c.

Add new config: CONFIG_USB_CABLE_CHECK. If defined then board
file should provide function: usb_cable_connected() (include/usb.h)
that return 1 if cable is connected and 0 otherwise.

Changes v2:
- add a note to the README

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Marek Vasut <marex@denx.de>

1 files changed, 21 insertions, 3 deletions

diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
index be6b418..b1fe8bd 100644
--- a/drivers/usb/gadget/f_mass_storage.c
+++ b/drivers/usb/gadget/f_mass_storage.c
@@ -243,6 +243,7 @@
 #include <config.h>
 #include <malloc.h>
 #include <common.h>
+#include <usb.h>
 
 #include <linux/err.h>
 #include <linux/usb/ch9.h>
@@ -675,6 +676,18 @@ static int sleep_thread(struct fsg_common *common)
 			k++;
 		}
 
+		if (k == 10) {
+			/* Handle CTRL+C */
+			if (ctrlc())
+				return -EPIPE;
+#ifdef CONFIG_USB_CABLE_CHECK
+			/* Check cable connection */
+			if (!usb_cable_connected())
+				return -EIO;
+#endif
+			k = 0;
+		}
+
 		usb_gadget_handle_interrupts();
 	}
 	common->thread_wakeup_needed = 0;
@@ -2387,6 +2400,7 @@ static void handle_exception(struct fsg_common *common)
 
 int fsg_main_thread(void *common_)
 {
+	int ret;
 	struct fsg_common	*common = the_fsg_common;
 	/* The main loop */
 	do {
@@ -2396,12 +2410,16 @@ int fsg_main_thread(void *common_)
 		}
 
 		if (!common->running) {
-			sleep_thread(common);
+			ret = sleep_thread(common);
+			if (ret)
+				return ret;
+
 			continue;
 		}
 
-		if (get_next_command(common))
-			continue;
+		ret = get_next_command(common);
+		if (ret)
+			return ret;
 
 		if (!exception_in_progress(common))
 			common->state = FSG_STATE_DATA_PHASE;