[PATCH v2 20/33] HID: logitech-hidpp: manage G920 range sysfs attribute via dev_groups

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Creating and removing the G920 range attribute manually inside force
feedback initialization and destruction ties sysfs cleanup to input
device release rather than driver unbind, leaving a dangling attribute
if userspace holds an open event handle across disconnect. Manual sysfs
management also adds avoidable boilerplate.

Register the attribute group through driver dev_groups with a visibility
callback checking initialized G920 force-feedback state, allowing driver
core to create and tear down the attribute cleanly around probe and
remove.

Tested-by: Gideon Heinz <gideonheinz02@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/hid/hid-logitech-hidpp.c | 45 +++++++++++++++++++++++++++++++++-------
 1 file changed, 37 insertions(+), 8 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 03d2e9077675..f24fa70d272e 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -2747,16 +2747,47 @@ static ssize_t hidpp_ff_range_store(struct device *dev, struct device_attribute
 
 static DEVICE_ATTR(range, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH, hidpp_ff_range_show, hidpp_ff_range_store);
 
+static struct attribute *g920_range_attrs[] = {
+	&dev_attr_range.attr,
+	NULL
+};
+
+static umode_t g920_range_attr_is_visible(struct kobject *kobj,
+					  struct attribute *attr, int idx)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct hid_device *hdev = to_hid_device(dev);
+	struct hidpp_device *hidpp = hid_get_drvdata(hdev);
+	struct g920_data *g920;
+
+	if (!hidpp || !(hidpp->quirks & HIDPP_QUIRK_CLASS_G920))
+		return 0;
+
+	g920 = hidpp->private_data;
+	if (!g920 || !g920->ff)
+		return 0;
+
+	return attr->mode;
+}
+
+static const struct attribute_group g920_range_group = {
+	.attrs = g920_range_attrs,
+	.is_visible = g920_range_attr_is_visible,
+};
+
+static const struct attribute_group *hidpp_dev_groups[] = {
+	&g920_range_group,
+	NULL
+};
+
 static void hidpp_ff_destroy(struct ff_device *ff)
 {
 	struct hidpp_ff_private_data *data = ff->private;
 	struct hidpp_device *hidpp = data->hidpp;
-	struct hid_device *hid = hidpp->hid_dev;
 	struct g920_data *g920 = hidpp->private_data;
 
-	hid_info(hid, "Unloading HID++ force feedback.\n");
+	hid_info(hidpp->hid_dev, "Unloading HID++ force feedback.\n");
 
-	device_remove_file(&hid->dev, &dev_attr_range);
 	destroy_workqueue(data->wq);
 	g920->ff = NULL;
 }
@@ -2843,11 +2874,6 @@ static int hidpp_ff_init(struct hidpp_device *hidpp, struct input_dev *dev)
 	dev->open = g920_input_open;
 	dev->close = g920_input_close;
 
-	/* Create sysfs interface */
-	error = device_create_file(&(hidpp->hid_dev->dev), &dev_attr_range);
-	if (error)
-		hid_warn(hidpp->hid_dev, "Unable to create sysfs interface for \"range\", errno %d!\n", error);
-
 	hid_info(hid, "Force feedback support loaded (firmware release %d).\n",
 		 version);
 
@@ -4985,6 +5011,9 @@ static struct hid_driver hidpp_driver = {
 	.input_configured = hidpp_input_configured,
 	.input_mapping = hidpp_input_mapping,
 	.input_mapped = hidpp_input_mapped,
+	.driver = {
+		.dev_groups = hidpp_dev_groups,
+	},
 };
 
 module_hid_driver(hidpp_driver);

-- 
2.56.0.542.g3ef89b7020-goog