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;
	u32 magnitudes;
	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];
	u32 mags = READ_ONCE(stadiaff->magnitudes);

	rumble_field->value[0] = mags & 0xffff;
	rumble_field->value[1] = (mags >> 16) & 0xffff;

	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);
	u32 mags = (u32)effect->u.rumble.strong_magnitude |
		  ((u32)effect->u.rumble.weak_magnitude << 16);

	WRITE_ONCE(stadiaff->magnitudes, mags);
	schedule_work(&stadiaff->work);

	return 0;
}

static int stadia_input_open(struct input_dev *dev)
{
	struct hid_device *hid = input_get_drvdata(dev);
	struct stadiaff_device *stadiaff = hid_get_drvdata(hid);
	int error;

	error = hid_hw_open(hid);
	if (error)
		return error;

	enable_work(&stadiaff->work);
	return 0;
}

static void stadia_input_close(struct input_dev *dev)
{
	struct hid_device *hid = input_get_drvdata(dev);
	struct stadiaff_device *stadiaff = hid_get_drvdata(hid);

	WRITE_ONCE(stadiaff->magnitudes, 0);
	stadiaff_work(&stadiaff->work);
	disable_work_sync(&stadiaff->work);

	hid_hw_close(hid);
}

static int stadia_input_configured(struct hid_device *hid, struct hid_input *hidinput)
{
	struct stadiaff_device *stadiaff;
	struct hid_report *report;
	struct input_dev *dev = hidinput->input;
	int error;

	if (!list_is_first(&hidinput->list, &hid->inputs))
		return 0;

	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->hid = hid;
	stadiaff->report = report;
	INIT_WORK(&stadiaff->work, stadiaff_work);
	disable_work_sync(&stadiaff->work);

	dev->open = stadia_input_open;
	dev->close = stadia_input_close;

	hid_info(hid, "Force Feedback for Google Stadia controller\n");

	return 0;
}

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,
	.input_configured = stadia_input_configured,
};
module_hid_driver(stadia_driver);

MODULE_DESCRIPTION("Google Stadia controller rumble support.");
MODULE_LICENSE("GPL");