[PATCH v1 2/3] tools/usbip: support use case reconnect: command bind

[Lars Gunnarsson <gunnarsson.lars@gmail.com>]

Extend command "usbip bind" with:

* flag "-c" to wait for busid to connect and then bind, instead of returning
  error.
* flag "-d", to wait for busid to disconnect before exit.

Today manual steps is required to re-export usb device when re-connected. With
above flags enabled, it's possible to permanently "export" usb devices with help
of example systemd or other process supervisors, or with a simple while-loop
in bash.

Signed-off-by: Lars Gunnarsson <gunnarsson.lars@gmail.com>
---
 tools/usb/usbip/src/usbip_bind.c | 62 +++++++++++++++++++++++++++-----
 1 file changed, 53 insertions(+), 9 deletions(-)

diff --git a/tools/usb/usbip/src/usbip_bind.c b/tools/usb/usbip/src/usbip_bind.c
index f1cf9225a69c..907c81f2160c 100644
--- a/tools/usb/usbip/src/usbip_bind.c
+++ b/tools/usb/usbip/src/usbip_bind.c
@@ -14,6 +14,7 @@
 #include <getopt.h>
 
 #include "usbip_common.h"
+#include "usbip_monitor.h"
 #include "utils.h"
 #include "usbip.h"
 #include "sysfs_utils.h"
@@ -24,10 +25,18 @@ enum unbind_status {
 	UNBIND_ST_FAILED
 };
 
+typedef struct {
+	char *busid;
+	char monitor_connect;
+	char monitor_disconnect;
+} bind_options;
+
 static const char usbip_bind_usage_string[] =
 	"usbip bind <args>\n"
-	"    -b, --busid=<busid>    Bind " USBIP_HOST_DRV_NAME ".ko to device "
-	"on <busid>\n";
+	"    -b, --busid=<busid>        Bind " USBIP_HOST_DRV_NAME ".ko to device\n"
+	"                               on <busid>\n"
+	"    -c, --monitor-connect      Wait until bus is available before binding\n"
+	"    -d, --monitor-disconnect   Wait until bus is disconnected before exit\n";
 
 void usbip_bind_usage(void)
 {
@@ -127,19 +136,32 @@ static int unbind_other(char *busid)
 	return status;
 }
 
-static int bind_device(char *busid)
+static int bind_device(bind_options options)
 {
 	int rc;
 	struct udev *udev;
 	struct udev_device *dev;
 	const char *devpath;
+	usbip_monitor_t *monitor = NULL;
+	char *busid = options.busid;
+
+	if (options.monitor_disconnect || options.monitor_connect) {
+		monitor = usbip_monitor_new();
+		usbip_monitor_set_busid(monitor, options.busid);
+	}
 
 	/* Check whether the device with this bus ID exists. */
 	udev = udev_new();
 	dev = udev_device_new_from_subsystem_sysname(udev, "usb", busid);
 	if (!dev) {
-		err("device with the specified bus ID does not exist");
-		return -1;
+		if (options.monitor_connect) {
+			info("device on busid %s: awaiting connect", busid);
+			usbip_monitor_await_usb_bind(monitor, USBIP_USB_DRV_NAME);
+			dev = udev_device_new_from_subsystem_sysname(udev, "usb", busid);
+		} else {
+			err("device with the specified bus ID does not exist");
+			return -1;
+		}
 	}
 	devpath = udev_device_get_devpath(dev);
 	udev_unref(udev);
@@ -174,7 +196,14 @@ static int bind_device(char *busid)
 		return -1;
 	}
 
-	info("bind device on busid %s: complete", busid);
+	info("device on busid %s: bind complete", busid);
+
+	if (options.monitor_disconnect) {
+		info("device on busid %s: await disconnect", busid);
+		usbip_monitor_await_usb_bind(monitor, USBIP_HOST_DRV_NAME);
+		usbip_monitor_await_usb_unbind(monitor);
+		usbip_monitor_delete(monitor);
+	}
 
 	return 0;
 }
@@ -183,27 +212,42 @@ int usbip_bind(int argc, char *argv[])
 {
 	static const struct option opts[] = {
 		{ "busid", required_argument, NULL, 'b' },
+		{ "monitor-connect",  no_argument, NULL, 'c' },
+		{ "monitor-disconnect",  no_argument, NULL, 'd' },
 		{ NULL,    0,                 NULL,  0  }
 	};
 
+	bind_options options = {};
 	int opt;
 	int ret = -1;
 
 	for (;;) {
-		opt = getopt_long(argc, argv, "b:", opts, NULL);
+		opt = getopt_long(argc, argv, "b:cd", opts, NULL);
 
 		if (opt == -1)
 			break;
 
 		switch (opt) {
 		case 'b':
-			ret = bind_device(optarg);
-			goto out;
+			options.busid = optarg;
+			break;
+		case 'c':
+			options.monitor_connect = 1;
+			break;
+		case 'd':
+			options.monitor_disconnect = 1;
+			break;
 		default:
 			goto err_out;
 		}
 	}
 
+	if (!options.busid)
+		goto err_out;
+
+	ret = bind_device(options);
+	goto out;
+
 err_out:
 	usbip_bind_usage();
 out:
-- 
2.25.1