hidraw: allow opening of sibling devices

Some mice have a separate hid interface for configuring the advanced
features. It occurs that this is a common enough use case to be handled
directly by libratbag-hidraw instead of having a per-device quirk.

The idea is to allow opening the sibling hidraw devices during .probe()
and to give a matching callback. If the callback succeeds, then the
hidraw node will be used.
With this, one device might be opened several times, this has to be fixed
in a separate commit.

Fixes issue #19

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>

src/driver-hidpp10.c

@@ -191,6 +191,12 @@ hidpp10drv_fill_from_profile(struct ratbag_device *device, struct hidpp10_device
 	return 0;
 }
 
+static int
+hidpp10drv_test_hidraw(struct ratbag_device *device)
+{
+	return ratbag_hidraw_has_report(device, REPORT_ID_SHORT);
+}
+
 static int
 hidpp10drv_probe(struct ratbag_device *device, const struct ratbag_id id)
 {
@@ -198,8 +204,10 @@ hidpp10drv_probe(struct ratbag_device *device, const struct ratbag_id id)
 	struct hidpp10drv_data *drv_data = NULL;
 	struct hidpp10_device *dev = NULL;
 
-	rc = ratbag_open_hidraw(device);
-	if (rc) {
+	rc = ratbag_find_hidraw(device, hidpp10drv_test_hidraw);
+	if (rc == -ENODEV) {
+		return rc;
+	} else if (rc) {
 		log_error(device->ratbag,
 			  "Can't open corresponding hidraw node: '%s' (%d)\n",
 			  strerror(-rc),
@@ -208,11 +216,6 @@ hidpp10drv_probe(struct ratbag_device *device, const struct ratbag_id id)
 		goto err;
 	}
 
-	if (!ratbag_hidraw_has_report(device, REPORT_ID_SHORT)) {
-		ratbag_close_hidraw(device);
-		return -ENODEV;
-	}
-
 	drv_data = zalloc(sizeof(*drv_data));
 
 	/* We can treat all devices as wired devices here. If we talk to the

src/driver-hidpp20.c

@@ -431,14 +431,22 @@ hidpp20drv_20_probe(struct ratbag_device *device, const struct ratbag_id id)
 
 }
 
+static int
+hidpp20drv_test_hidraw(struct ratbag_device *device)
+{
+	return ratbag_hidraw_has_report(device, REPORT_ID_LONG);
+}
+
 static int
 hidpp20drv_probe(struct ratbag_device *device, const struct ratbag_id id)
 {
 	int rc;
 	struct hidpp20drv_data *drv_data;
 
-	rc = ratbag_open_hidraw(device);
-	if (rc) {
+	rc = ratbag_find_hidraw(device, hidpp20drv_test_hidraw);
+	if (rc == -ENODEV) {
+		return rc;
+	} else if (rc) {
 		log_error(device->ratbag,
 			  "Can't open corresponding hidraw node: '%s' (%d)\n",
 			  strerror(-rc),
@@ -446,11 +454,6 @@ hidpp20drv_probe(struct ratbag_device *device, const struct ratbag_id id)
 		return -ENODEV;
 	}
 
-	if (!ratbag_hidraw_has_report(device, REPORT_ID_LONG)) {
-		ratbag_close_hidraw(device);
-		return -ENODEV;
-	}
-
 	drv_data = zalloc(sizeof(*drv_data));
 	ratbag_set_drv_data(device, drv_data);
 

src/libratbag-hidraw.c

@@ -212,6 +212,70 @@ ratbag_open_hidraw(struct ratbag_device *device)
 	return rc;
 }
 
+int
+ratbag_find_hidraw(struct ratbag_device *device, int (*match)(struct ratbag_device *device))
+{
+	struct ratbag *ratbag = device->ratbag;
+	struct udev_enumerate *e;
+	struct udev_list_entry *entry;
+	struct udev_device *udev_device;
+	const char *path, *sysname;
+	struct udev_device *hid_udev;
+	struct udev_device *parent_udev;
+	struct udev *udev = ratbag->udev;
+	int rc = -ENODEV;
+	int matched;
+
+	assert(match);
+
+	hid_udev = udev_device_get_parent_with_subsystem_devtype(device->udev_device, "hid", NULL);
+
+	if (!hid_udev)
+		return -ENODEV;
+
+	if (device->ids.bustype == BUS_USB)
+		/* using the parent usb_device to match siblings */
+		parent_udev = udev_device_get_parent_with_subsystem_devtype(hid_udev, "usb", "usb_device");
+	else
+		parent_udev = hid_udev;
+
+	e = udev_enumerate_new(udev);
+	udev_enumerate_add_match_subsystem(e, "hidraw");
+	udev_enumerate_add_match_parent(e, parent_udev);
+	udev_enumerate_scan_devices(e);
+	udev_list_entry_foreach(entry, udev_enumerate_get_list_entry(e)) {
+		path = udev_list_entry_get_name(entry);
+		udev_device = udev_device_new_from_syspath(udev, path);
+		if (!udev_device)
+			continue;
+
+		sysname = udev_device_get_sysname(udev_device);
+		if (!strneq("hidraw", sysname, 6)) {
+			udev_device_unref(udev_device);
+			continue;
+		}
+
+		rc = ratbag_open_hidraw_node(device, udev_device);
+		if (rc)
+			ratbag_close_hidraw(device);
+
+		matched = match(device);
+		udev_device_unref(udev_device);
+
+		if (matched == 1) {
+			rc = 0;
+			goto out;
+		}
+
+		rc = -ENODEV;
+	}
+
+out:
+	udev_enumerate_unref(e);
+
+	return rc;
+}
+
 int
 ratbag_hidraw_has_report(struct ratbag_device *device, uint8_t report_id)
 {

src/libratbag-hidraw.h

@@ -49,6 +49,19 @@ struct ratbag_hidraw {
  */
 int ratbag_open_hidraw(struct ratbag_device *device);
 
+/**
+ * Find and open the hidraw device associated with the device by using the
+ * given matching function.
+ *
+ * @param device the ratbag device
+ * @param match the matching test (return 1 if matched, 0 if not)
+ *
+ * @return 0 on success or a negative errno on error
+ */
+int
+ratbag_find_hidraw(struct ratbag_device *device,
+		   int (*match)(struct ratbag_device *device));
+
 /**
  * Close the hidraw device associated with the device.
  *