usb gadget0: ctrl write/read loopback tests

This is based on linux's gadget0 intel loopback tests, and also github
pr: https://github.com/libopencm3/libopencm3/pull/592

Note that this captures the currently broken control loopback issues on
dwc_otg devices.

See https://github.com/libopencm3/libopencm3/issues/873 and all linked
issues.

Current status is passing on f3, f0, and failing on f4.

tests/gadget-zero/test_gadget0.py

@@ -3,6 +3,7 @@ import datetime
 import random
 import usb.core
 import usb.util as uu
+import random
 import sys
 
 import unittest
@@ -25,6 +26,8 @@ GZ_REQ_SET_ALIGNED=3
 GZ_REQ_SET_UNALIGNED=4
 GZ_REQ_WRITE_LOOPBACK_BUFFER=10
 GZ_REQ_READ_LOOPBACK_BUFFER=11
+GZ_REQ_INTEL_WRITE=0x5b
+GZ_REQ_INTEL_READ=0x5c
 
 class find_by_serial(object):
     def __init__(self, serial):
@@ -83,6 +86,41 @@ class TestGadget0(unittest.TestCase):
             # Note, this might not be as portable as we'd like.
             self.assertIn("Pipe", e.strerror)
 
+class TestIntelCompliance(unittest.TestCase):
+    """
+    Part of intel's usb 2.0 compliance is writing and reading back control transfers
+    """
+    def setUp(self):
+        self.dev = usb.core.find(idVendor=VENDOR_ID, idProduct=PRODUCT_ID, custom_match=find_by_serial(DUT_SERIAL))
+        self.assertIsNotNone(self.dev, "Couldn't find locm3 gadget0 device")
+
+        self.cfg = uu.find_descriptor(self.dev, bConfigurationValue=2)
+        self.assertIsNotNone(self.cfg, "Config 2 should exist")
+        self.dev.set_configuration(self.cfg)
+
+    def tearDown(self):
+        uu.dispose_resources(self.dev)
+
+    def inner_t(self, mylen):
+        data = [random.randrange(255) for x in range(mylen)]
+        written = self.dev.ctrl_transfer(uu.CTRL_OUT | uu.CTRL_RECIPIENT_INTERFACE | uu.CTRL_TYPE_VENDOR, GZ_REQ_INTEL_WRITE, 0, 0, data)
+        self.assertEqual(written, len(data), "Should have written all bytes plz")
+        # now. in _theory_ I should be able to make a bulk transfer here and have it not "interfere"
+        # fixme - try this out?
+        read = self.dev.ctrl_transfer(uu.CTRL_IN | uu.CTRL_RECIPIENT_INTERFACE | uu.CTRL_TYPE_VENDOR, GZ_REQ_INTEL_READ, 0, 0, mylen)
+        self.assertEqual(mylen, len(read))
+        expected = array.array('B', [x for x in data])
+        self.assertEqual(expected, read, "should have read back what we wrote")
+
+    def test_ctrl_loopbacks(self):
+        self.inner_t(0)
+        self.inner_t(10)
+        self.inner_t(63)
+        self.inner_t(64)
+        self.inner_t(65)
+        self.inner_t(140)
+        self.inner_t(183)
+
 
 class TestConfigSourceSink(unittest.TestCase):
     """

tests/gadget-zero/usb-gadget0.c

@@ -280,7 +280,6 @@ static enum usbd_request_return_codes gadget0_control_request(usbd_device *usbd_
 	(void) usbd_dev;
 	(void) complete;
 	(void) buf;
-	(void) len;
 	ER_DPRINTF("ctrl breq: %x, bmRT: %x, windex :%x, wlen: %x, wval :%x\n",
 		req->bRequest, req->bmRequestType, req->wIndex, req->wLength,
 		req->wValue);
@@ -292,9 +291,31 @@ static enum usbd_request_return_codes gadget0_control_request(usbd_device *usbd_
 		state.pattern = req->wValue;
 		return USBD_REQ_HANDLED;
 	case INTEL_COMPLIANCE_WRITE:
+		/* accept correctly formed ctrl writes */
+		if (req->bmRequestType != (USB_REQ_TYPE_VENDOR|USB_REQ_TYPE_INTERFACE)) {
+			return USBD_REQ_NOTSUPP;
+		}
+		if (req->wValue || req->wIndex) {
+			return USBD_REQ_NOTSUPP;
+		}
+		if (req->wLength > sizeof(usbd_control_buffer)) {
+			return USBD_REQ_NOTSUPP;
+		}
+		/* ok, mark it as accepted. */
+		return USBD_REQ_HANDLED;
 	case INTEL_COMPLIANCE_READ:
-		ER_DPRINTF("unimplemented!");
-		return USBD_REQ_NOTSUPP;
+		if (req->bmRequestType != (USB_REQ_TYPE_IN|USB_REQ_TYPE_VENDOR|USB_REQ_TYPE_INTERFACE)) {
+			return USBD_REQ_NOTSUPP;
+		}
+		if (req->wValue || req->wIndex) {
+			return USBD_REQ_NOTSUPP;
+		}
+		if (req->wLength > sizeof(usbd_control_buffer)) {
+			return USBD_REQ_NOTSUPP;
+		}
+		/* ok, return what they left there earlier */
+		*len = req->wLength;
+		return USBD_REQ_HANDLED;
 	case GZ_REQ_SET_UNALIGNED:
 		state.test_unaligned = 1;
 		return USBD_REQ_HANDLED;
@@ -316,6 +337,9 @@ static enum usbd_request_return_codes gadget0_control_request(usbd_device *usbd_
 			*len = req->wValue;
 		}
 		return USBD_REQ_HANDLED;
+	default:
+		ER_DPRINTF("Unhandled request!\n");
+		return USBD_REQ_NOTSUPP;
 	}
 	return USBD_REQ_NEXT_CALLBACK;
 }