[PATCH] USB: Patch to make usbmon to print control setup packets

Make usbmon to print Setup packets of Control transfers. This is useful
when debugging enumeration issues.

This is a change to the trace format which is not fully compatible.
A parser has to look at the data length word now. If that word is
a character like 's', read setup packet before proceeding with data.
I decided not to bump the API tag for this because not many such
parsers exist at this point.

Signed-off-by: Pete Zaitcev <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/usb/usbmon.txt

···
   or 3 and 2 positions, correspondingly.
 - URB Status. This field makes no sense for submissions, but is present
   to help scripts with parsing. In error case, it contains the error code.
+  In case of a setup packet, it contains a Setup Tag. If scripts read a number
+  in this field, the proceed to read Data Length. Otherwise, they read
+  the setup packet before reading the Data Length.
+- Setup packet, if present, consists of 5 words: one of each for bmRequestType,
+  bRequest, wValue, wIndex, wLength, as specified by the USB Specification 2.0.
+  These words are safe to decode if Setup Tag was 's'. Otherwise, the setup
+  packet was present, but not captured, and the fields contain filler.
 - Data Length. This is the actual length in the URB.
 - Data tag. The usbmon may not always capture data, even if length is nonzero.
   Only if tag is '=', the data words are present.
···
 			String data_str = st.nextToken();
 			int len = data_str.length() / 2;
 			int i;
+			int b;	// byte is signed, apparently?! XXX
 			for (i = 0; i < len; i++) {
-				data[data_len] = Byte.parseByte(
-				    data_str.substring(i*2, i*2 + 2),
-				    16);
+				// data[data_len] = Byte.parseByte(
+				//     data_str.substring(i*2, i*2 + 2),
+				//     16);
+				b = Integer.parseInt(
+				     data_str.substring(i*2, i*2 + 2),
+				     16);
+				if (b >= 128)
+					b *= -1;
+				data[data_len] = (byte) b;
 				data_len++;
 			}
 		}
 	}
 }
 
-This format is obviously deficient. For example, the setup packet for control
-transfers is not delivered. This will change in the future.
+This format may be changed in the future.
 
 Examples:
 
-An input control transfer to get a port status:
+An input control transfer to get a port status.
 
-d74ff9a0 2640288196 S Ci:001:00 -115 4 <
-d74ff9a0 2640288202 C Ci:001:00 0 4 = 01010100
+d5ea89a0 3575914555 S Ci:001:00 s a3 00 0000 0003 0004 4 <
+d5ea89a0 3575914560 C Ci:001:00 0 4 = 01050000
 
 An output bulk transfer to send a SCSI command 0x5E in a 31-byte Bulk wrapper
 to a storage device at address 5:

drivers/usb/mon/mon_text.c

···
 #define DATA_MAX  32
 
 /*
+ * Defined by USB 2.0 clause 9.3, table 9.2.
+ */
+#define SETUP_MAX  8
+
+/*
  * This limit exists to prevent OOMs when the user process stops reading.
  */
 #define EVENT_MAX  25
 
-#define PRINTF_DFL  120
+#define PRINTF_DFL  130
 
 struct mon_event_text {
 	struct list_head e_link;
···
 	unsigned int tstamp;
 	int length;		/* Depends on type: xfer length or act length */
 	int status;
+	char setup_flag;
 	char data_flag;
+	unsigned char setup[SETUP_MAX];
 	unsigned char data[DATA_MAX];
 };
 
···
  * This is called with the whole mon_bus locked, so no additional lock.
  */
 
+static inline char mon_text_get_setup(struct mon_event_text *ep,
+    struct urb *urb, char ev_type)
+{
+
+	if (!usb_pipecontrol(urb->pipe) || ev_type != 'S')
+		return '-';
+
+	if (urb->transfer_flags & URB_NO_SETUP_DMA_MAP)
+		return 'D';
+	if (urb->setup_packet == NULL)
+		return 'Z';	/* '0' would be not as pretty. */
+
+	memcpy(ep->setup, urb->setup_packet, SETUP_MAX);
+	return 0;
+}
+
 static inline char mon_text_get_data(struct mon_event_text *ep, struct urb *urb,
     int len, char ev_type)
 {
···
 
 	/*
 	 * Bulk is easy to shortcut reliably. 
-	 * XXX Control needs setup packet taken.
 	 * XXX Other pipe types need consideration. Currently, we overdo it
 	 * and collect garbage for them: better more than less.
 	 */
···
 	/* Collecting status makes debugging sense for submits, too */
 	ep->status = urb->status;
 
+	ep->setup_flag = mon_text_get_setup(ep, urb, ev_type);
 	ep->data_flag = mon_text_get_data(ep, urb, ep->length, ev_type);
 
 	rp->nevents++;
···
 	default: /* PIPE_BULK */  utype = 'B';
 	}
 	cnt += snprintf(pbuf + cnt, limit - cnt,
-	    "%lx %u %c %c%c:%03u:%02u %d %d",
+	    "%lx %u %c %c%c:%03u:%02u",
 	    ep->id, ep->tstamp, ep->type,
-	    utype, udir, usb_pipedevice(ep->pipe), usb_pipeendpoint(ep->pipe),
-	    ep->status, ep->length);
+	    utype, udir, usb_pipedevice(ep->pipe), usb_pipeendpoint(ep->pipe));
+
+	if (ep->setup_flag == 0) {   /* Setup packet is present and captured */
+		cnt += snprintf(pbuf + cnt, limit - cnt,
+		    " s %02x %02x %04x %04x %04x",
+		    ep->setup[0],
+		    ep->setup[1],
+		    (ep->setup[3] << 8) | ep->setup[2],
+		    (ep->setup[5] << 8) | ep->setup[4],
+		    (ep->setup[7] << 8) | ep->setup[6]);
+	} else if (ep->setup_flag != '-') { /* Unable to capture setup packet */
+		cnt += snprintf(pbuf + cnt, limit - cnt,
+		    " %c __ __ ____ ____ ____", ep->setup_flag);
+	} else {                     /* No setup for this kind of URB */
+		cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->status);
+	}
+	cnt += snprintf(pbuf + cnt, limit - cnt, " %d", ep->length);
 
 	if ((data_len = ep->length) > 0) {
 		if (ep->data_flag == 0) {