HID: hid-google-stadiaff: add support for Stadia force feedback

Add a hid-google-stadiaff module to support rumble based force feedback
on the Google Stadia controller. This works using the HID output
endpoint exposed on both the USB and BLE interface.
Signed-off-by: Fabio Baltieri <fabiobaltieri@chromium.org>
Reviewed-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/Kconfig

@@ -412,6 +412,13 @@ config HID_GOOGLE_HAMMER
 	help
 	Say Y here if you have a Google Hammer device.
 
+config HID_GOOGLE_STADIA_FF
+	tristate "Google Stadia force feedback"
+	select INPUT_FF_MEMLESS
+	help
+	Say Y here if you want to enable force feedback support for the Google
+	Stadia controller.
+
 config HID_VIVALDI
 	tristate "Vivaldi Keyboard"
 	select HID_VIVALDI_COMMON

drivers/hid/Makefile

@@ -55,6 +55,7 @@ obj-$(CONFIG_HID_GFRM)		+= hid-gfrm.o
 obj-$(CONFIG_HID_GLORIOUS)  += hid-glorious.o
 obj-$(CONFIG_HID_VIVALDI_COMMON) += hid-vivaldi-common.o
 obj-$(CONFIG_HID_GOOGLE_HAMMER)	+= hid-google-hammer.o
+obj-$(CONFIG_HID_GOOGLE_STADIA_FF)	+= hid-google-stadiaff.o
 obj-$(CONFIG_HID_VIVALDI)	+= hid-vivaldi.o
 obj-$(CONFIG_HID_GT683R)	+= hid-gt683r.o
 obj-$(CONFIG_HID_GYRATION)	+= hid-gyration.o

drivers/hid/hid-google-stadiaff.c

+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Stadia controller rumble support.
+ *
+ * Copyright 2023 Google LLC
+ */
+
+#include <linux/hid.h>
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+#define STADIA_FF_REPORT_ID 5
+
+struct stadiaff_device {
+	struct hid_device *hid;
+	struct hid_report *report;
+	spinlock_t lock;
+	bool removed;
+	uint16_t strong_magnitude;
+	uint16_t weak_magnitude;
+	struct work_struct work;
+};
+
+static void stadiaff_work(struct work_struct *work)
+{
+	struct stadiaff_device *stadiaff =
+		container_of(work, struct stadiaff_device, work);
+	struct hid_field *rumble_field = stadiaff->report->field[0];
+	unsigned long flags;
+
+	spin_lock_irqsave(&stadiaff->lock, flags);
+	rumble_field->value[0] = stadiaff->strong_magnitude;
+	rumble_field->value[1] = stadiaff->weak_magnitude;
+	spin_unlock_irqrestore(&stadiaff->lock, flags);
+
+	hid_hw_request(stadiaff->hid, stadiaff->report, HID_REQ_SET_REPORT);
+}
+
+static int stadiaff_play(struct input_dev *dev, void *data,
+			 struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct stadiaff_device *stadiaff = hid_get_drvdata(hid);
+	unsigned long flags;
+
+	spin_lock_irqsave(&stadiaff->lock, flags);
+	if (!stadiaff->removed) {
+		stadiaff->strong_magnitude = effect->u.rumble.strong_magnitude;
+		stadiaff->weak_magnitude = effect->u.rumble.weak_magnitude;
+		schedule_work(&stadiaff->work);
+	}
+	spin_unlock_irqrestore(&stadiaff->lock, flags);
+
+	return 0;
+}
+
+static int stadiaff_init(struct hid_device *hid)
+{
+	struct stadiaff_device *stadiaff;
+	struct hid_report *report;
+	struct hid_input *hidinput;
+	struct input_dev *dev;
+	int error;
+
+	if (list_empty(&hid->inputs)) {
+		hid_err(hid, "no inputs found\n");
+		return -ENODEV;
+	}
+	hidinput = list_entry(hid->inputs.next, struct hid_input, list);
+	dev = hidinput->input;
+
+	report = hid_validate_values(hid, HID_OUTPUT_REPORT,
+				     STADIA_FF_REPORT_ID, 0, 2);
+	if (!report)
+		return -ENODEV;
+
+	stadiaff = devm_kzalloc(&hid->dev, sizeof(struct stadiaff_device),
+				GFP_KERNEL);
+	if (!stadiaff)
+		return -ENOMEM;
+
+	hid_set_drvdata(hid, stadiaff);
+
+	input_set_capability(dev, EV_FF, FF_RUMBLE);
+
+	error = input_ff_create_memless(dev, NULL, stadiaff_play);
+	if (error)
+		return error;
+
+	stadiaff->removed = false;
+	stadiaff->hid = hid;
+	stadiaff->report = report;
+	INIT_WORK(&stadiaff->work, stadiaff_work);
+	spin_lock_init(&stadiaff->lock);
+
+	hid_info(hid, "Force Feedback for Google Stadia controller\n");
+
+	return 0;
+}
+
+static int stadia_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		return ret;
+	}
+
+	ret = stadiaff_init(hdev);
+	if (ret) {
+		hid_err(hdev, "force feedback init failed\n");
+		hid_hw_stop(hdev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void stadia_remove(struct hid_device *hid)
+{
+	struct stadiaff_device *stadiaff = hid_get_drvdata(hid);
+	unsigned long flags;
+
+	spin_lock_irqsave(&stadiaff->lock, flags);
+	stadiaff->removed = true;
+	spin_unlock_irqrestore(&stadiaff->lock, flags);
+
+	cancel_work_sync(&stadiaff->work);
+	hid_hw_stop(hid);
+}
+
+static const struct hid_device_id stadia_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_STADIA) },
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_STADIA) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, stadia_devices);
+
+static struct hid_driver stadia_driver = {
+	.name = "stadia",
+	.id_table = stadia_devices,
+	.probe = stadia_probe,
+	.remove = stadia_remove,
+};
+module_hid_driver(stadia_driver);
+
+MODULE_LICENSE("GPL");

drivers/hid/hid-ids.h

@@ -531,6 +531,7 @@
 #define USB_DEVICE_ID_GOOGLE_DON	0x5050
 #define USB_DEVICE_ID_GOOGLE_EEL	0x5057
 #define USB_DEVICE_ID_GOOGLE_JEWEL	0x5061
+#define USB_DEVICE_ID_GOOGLE_STADIA	0x9400
 
 #define USB_VENDOR_ID_GOTOP		0x08f2
 #define USB_DEVICE_ID_SUPER_Q2		0x007f