st/prober: Allow "found" functions called by prober to make more than one device.

src/xrt/drivers/psmv/psmv_driver.c

@@ -446,7 +446,7 @@ int
 psmv_found(struct xrt_prober *xp,
            struct xrt_prober_device **devices,
            size_t index,
-           struct xrt_device **out_xdev)
+           struct xrt_device **out_xdevs)
 {
 	struct os_hid_device *hid = NULL;
 	int ret;
@@ -506,6 +506,6 @@ psmv_found(struct xrt_prober *xp,
 	psmv_read_hid(psmv);
 
 	// And finally done
-	*out_xdev = &psmv->base;
-	return 0;
+	*out_xdevs = &psmv->base;
+	return 1;
 }

src/xrt/drivers/psmv/psmv_interface.h

@@ -33,7 +33,7 @@ int
 psmv_found(struct xrt_prober *xp,
            struct xrt_prober_device **devices,
            size_t index,
-           struct xrt_device **out_xdev);
+           struct xrt_device **out_xdevs);
 
 /*!
  * @dir drivers/psmv

src/xrt/include/xrt/xrt_prober.h

@@ -27,6 +27,14 @@ extern "C" {
 struct xrt_prober;
 struct xrt_prober_device;
 
+/*!
+ * The maximum number of devices that a single "found" function called by the
+ * prober can create per-call.
+ *
+ * @ingroup xrt_iface
+ */
+#define XRT_MAX_DEVICES_PER_PROBE 16
+
 /*!
  * Entry for a single device.
  *
@@ -40,7 +48,7 @@ struct xrt_prober_entry
 	int (*found)(struct xrt_prober *xp,
 	             struct xrt_prober_device **devices,
 	             size_t index,
-	             struct xrt_device **out_xdev);
+	             struct xrt_device **out_xdevs);
 
 	const char *name;
 };

src/xrt/state_trackers/prober/p_prober.c

@@ -444,14 +444,28 @@ select_device(struct xrt_prober* xp,
 				continue;
 			}
 
-			struct xrt_device* xdev = NULL;
-			entry->found(xp, dev_list, i, &xdev);
+			struct xrt_device*
+			    new_xdevs[XRT_MAX_DEVICES_PER_PROBE] = {NULL};
+			int num_found =
+			    entry->found(xp, dev_list, i, &(new_xdevs[0]));
 
-			if (xdev == NULL) {
+			if (num_found <= 0) {
 				continue;
 			}
-
-			handle_found_device(p, xdevs, num_xdevs, xdev);
+			for (int created_idx = 0; created_idx < num_found;
+			     ++created_idx) {
+				if (new_xdevs[created_idx] == NULL) {
+					P_DEBUG(
+					    p,
+					    "Leaving device creation loop "
+					    "early: found function reported %i "
+					    "created, but only %i non-null",
+					    num_found, created_idx);
+					continue;
+				}
+				handle_found_device(p, xdevs, num_xdevs,
+				                    new_xdevs[created_idx]);
+			}
 		}
 	}
 

src/xrt/targets/common/target_lists.c

@@ -34,11 +34,13 @@
  * - `struct xrt_prober *xp`
  * - `struct xrt_prober_device **devices`
  * - `size_t index`
- * - `struct xrt_device **out_xdev`
+ * - `struct xrt_device **out_xdevs` (an array of XRT_MAX_DEVICES_PER_PROBE
+ * xrt_device pointers)
  *
  * It is called when devices[index] match the VID and PID in the list.
- * It should return 0 if it decides not to create any devices, or 1 if it
- * creates one: it should assign *out_xdev to the created device.
+ * It should return 0 if it decides not to create any devices, negative on
+ * error, and the number of devices created if it creates one or more: it should
+ * assign sequential elements of out_xdevs to the created devices.
  */
 struct xrt_prober_entry target_entry_list[] = {
 #ifdef XRT_BUILD_PSVR