[PATCH v2 1/3] HID: apple-ibridge: Add Apple iBridge HID driver.

[Ronald TschalÃr]

The iBridge device provides access to several devices, including:
- the Touch Bar
- the iSight webcam
- the light sensor
- the fingerprint sensor

This driver provides the core support for managing the iBridge device
and the access to the underlying devices. In particular, since the
functionality for the touch bar and light sensor is exposed via USB HID
interfaces, and the same HID device is used for multiple functions, this
driver creates virtual HID devices, one per real HID device and
sub-driver pair (for a total of 4 virtual HID devices). The sub-drivers
then bind to these virtual HID devices.

This way the Touch Bar and ALS drivers can be kept in their own modules,
while at the same time making them look very much like as if they were
connected to the real HID devices; e.g. in particular the Touch Bar
driver is aware of the fact that it is dealing with two HID devices that
need to managed differently.

Signed-off-by: Ronald TschalÃr <ronald@xxxxxxxxxxxxx>
---
 drivers/hid/Kconfig           |  14 +
 drivers/hid/Makefile          |   1 +
 drivers/hid/apple-ibridge.c   | 585 ++++++++++++++++++++++++++++++++++
 drivers/hid/hid-ids.h         |   1 +
 include/linux/apple-ibridge.h |  23 ++
 5 files changed, 624 insertions(+)
 create mode 100644 drivers/hid/apple-ibridge.c
 create mode 100644 include/linux/apple-ibridge.h

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 4ca0cdfa6b33..545d3691fc1c 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -135,6 +135,20 @@ config HID_APPLE
 	Say Y here if you want support for keyboards of	Apple iBooks, PowerBooks,
 	MacBooks, MacBook Pros and Apple Aluminum.
 
+config HID_APPLE_IBRIDGE
+	tristate "Apple iBridge"
+	depends on ACPI
+	depends on USB_HID
+	depends on X86 || COMPILE_TEST
+	help
+	  This module provides the core support for the Apple T1 chip found
+	  on recent MacBookPro's, also known as the iBridge. The drivers for
+	  the Touch Bar (apple-ib-tb) and light sensor (apple-ib-als) need to
+	  be enabled separately.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called apple-ibridge.
+
 config HID_APPLEIR
 	tristate "Apple infrared receiver"
 	depends on (USB_HID)
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 170163b41303..a4da5663a541 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_HID_ACCUTOUCH)	+= hid-accutouch.o
 obj-$(CONFIG_HID_ALPS)		+= hid-alps.o
 obj-$(CONFIG_HID_ACRUX)		+= hid-axff.o
 obj-$(CONFIG_HID_APPLE)		+= hid-apple.o
+obj-$(CONFIG_HID_APPLE_IBRIDGE)	+= apple-ibridge.o
 obj-$(CONFIG_HID_APPLEIR)	+= hid-appleir.o
 obj-$(CONFIG_HID_ASUS)		+= hid-asus.o
 obj-$(CONFIG_HID_AUREAL)	+= hid-aureal.o
diff --git a/drivers/hid/apple-ibridge.c b/drivers/hid/apple-ibridge.c
new file mode 100644
index 000000000000..565f080a38d6
--- /dev/null
+++ b/drivers/hid/apple-ibridge.c
@@ -0,0 +1,585 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Apple iBridge Driver
+ *
+ * Copyright (c) 2018 Ronald TschalÃr
+ */
+
+/**
+ * DOC: Overview
+ *
+ * MacBookPro models with a Touch Bar (13,[23] and 14,[23]) have an Apple
+ * iBridge chip (also known as T1 chip) which exposes the touch bar,
+ * built-in webcam (iSight), ambient light sensor, and Secure Enclave
+ * Processor (SEP) for TouchID. It shows up in the system as a USB device
+ * with 3 configurations: 'Default iBridge Interfaces', 'Default iBridge
+ * Interfaces(OS X)', and 'Default iBridge Interfaces(Recovery)'. While
+ * the second one is used by MacOS to provide the fancy touch bar
+ * functionality with custom buttons etc, this driver just uses the first.
+ *
+ * In the first (default after boot) configuration, 4 usb interfaces are
+ * exposed: 2 related to the webcam, and 2 USB HID interfaces representing
+ * the touch bar and the ambient light sensor. The webcam interfaces are
+ * already handled by the uvcvideo driver; furthermore, the handling of the
+ * input reports when "keys" on the touch bar are pressed is already handled
+ * properly by the generic USB HID core. This leaves the management of the
+ * touch bar modes (e.g. switching between function and special keys when the
+ * FN key is pressed), the touch bar display (dimming and turning off), the
+ * key-remapping when the FN key is pressed, and handling of the light sensor.
+ *
+ * This driver is implemented as a HID driver that creates virtual HID devices
+ * for the ALS and touch bar functionality, and the ALS and touch bar drivers
+ * are HID drivers which in turn attach to these virtual HID devices. This
+ * driver then relays the calls on the real HID devices to the virtual ones,
+ * and visa versa.
+ *
+ * Lastly, this driver also takes care of the power-management for the
+ * iBridge when suspending and resuming.
+ */
+
+#include <linux/acpi.h>
+#include <linux/apple-ibridge.h>
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include "hid-ids.h"
+#include "../hid/usbhid/usbhid.h"
+
+#define APPLEIB_BASIC_CONFIG	1
+
+#define	LOG_DEV(ib_dev)		(&(ib_dev)->acpi_dev->dev)
+
+static struct hid_device_id appleib_sub_hid_ids[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_LINUX_FOUNDATION,
+			 USB_DEVICE_ID_IBRIDGE_TB) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_LINUX_FOUNDATION,
+			 USB_DEVICE_ID_IBRIDGE_ALS) },
+};
+
+struct appleib_device {
+	struct acpi_device		*acpi_dev;
+	acpi_handle			asoc_socw;
+};
+
+struct appleib_hid_dev_info {
+	struct hid_device	*hdev;
+	struct hid_device	*sub_hdevs[ARRAY_SIZE(appleib_sub_hid_ids)];
+};
+
+static void appleib_remove_device(struct hid_device *hdev)
+{
+	struct appleib_hid_dev_info *hdev_info = hid_get_drvdata(hdev);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(hdev_info->sub_hdevs); i++)
+		hid_destroy_device(hdev_info->sub_hdevs[i]);
+
+	hid_set_drvdata(hdev, NULL);
+}
+
+/**
+ * appleib_forward_int_op() - Forward a hid-driver callback to all drivers on
+ * all virtual HID devices attached to the given real HID device.
+ * @hdev the real hid-device
+ * @forward a function that calls the callback on the given driver
+ * @args arguments for the forward function
+ *
+ * This is for callbacks that return a status as an int.
+ *
+ * Returns: 0 on success, or the first error returned by the @forward function.
+ */
+static int appleib_forward_int_op(struct hid_device *hdev,
+				  int (*forward)(struct hid_driver *,
+						 struct hid_device *, void *),
+				  void *args)
+{
+	struct appleib_hid_dev_info *hdev_info = hid_get_drvdata(hdev);
+	struct hid_device *sub_hdev;
+	int rc = 0;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(hdev_info->sub_hdevs); i++) {
+		sub_hdev = hdev_info->sub_hdevs[i];
+		if (sub_hdev->driver) {
+			rc = forward(sub_hdev->driver, sub_hdev, args);
+			if (rc)
+				break;
+		}
+
+		break;
+	}
+
+	return rc;
+}
+
+static int appleib_hid_raw_event(struct hid_device *hdev,
+				 struct hid_report *report, u8 *data, int size)
+{
+	struct appleib_hid_dev_info *hdev_info = hid_get_drvdata(hdev);
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(hdev_info->sub_hdevs); i++)
+		hid_input_report(hdev_info->sub_hdevs[i], report->type, data,
+				 size, 0);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int appleib_hid_suspend_fwd(struct hid_driver *drv,
+				   struct hid_device *hdev, void *args)
+{
+	int rc = 0;
+
+	if (drv->suspend)
+		rc = drv->suspend(hdev, *(pm_message_t *)args);
+
+	return rc;
+}
+
+static int appleib_hid_suspend(struct hid_device *hdev, pm_message_t message)
+{
+	return appleib_forward_int_op(hdev, appleib_hid_suspend_fwd, &message);
+}
+
+static int appleib_hid_resume_fwd(struct hid_driver *drv,
+				  struct hid_device *hdev, void *args)
+{
+	int rc = 0;
+
+	if (drv->resume)
+		rc = drv->resume(hdev);
+
+	return rc;
+}
+
+static int appleib_hid_resume(struct hid_device *hdev)
+{
+	return appleib_forward_int_op(hdev, appleib_hid_resume_fwd, NULL);
+}
+
+static int appleib_hid_reset_resume_fwd(struct hid_driver *drv,
+					struct hid_device *hdev, void *args)
+{
+	int rc = 0;
+
+	if (drv->reset_resume)
+		rc = drv->reset_resume(hdev);
+
+	return rc;
+}
+
+static int appleib_hid_reset_resume(struct hid_device *hdev)
+{
+	return appleib_forward_int_op(hdev, appleib_hid_reset_resume_fwd, NULL);
+}
+#endif /* CONFIG_PM */
+
+/**
+ * appleib_find_report_field() - Find the field in the report with the given
+ * usage.
+ * @report: the report to search
+ * @field_usage: the usage of the field to search for
+ *
+ * Returns: the hid field if found, or NULL if none found.
+ */
+struct hid_field *appleib_find_report_field(struct hid_report *report,
+					    unsigned int field_usage)
+{
+	int f, u;
+
+	for (f = 0; f < report->maxfield; f++) {
+		struct hid_field *field = report->field[f];
+
+		if (field->logical == field_usage)
+			return field;
+
+		for (u = 0; u < field->maxusage; u++) {
+			if (field->usage[u].hid == field_usage)
+				return field;
+		}
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(appleib_find_report_field);
+
+/**
+ * appleib_find_hid_field() - Search all the reports of the device for the
+ * field with the given usage.
+ * @hdev: the device whose reports to search
+ * @application: the usage of application collection that the field must
+ *               belong to
+ * @field_usage: the usage of the field to search for
+ *
+ * Returns: the hid field if found, or NULL if none found.
+ */
+struct hid_field *appleib_find_hid_field(struct hid_device *hdev,
+					 unsigned int application,
+					 unsigned int field_usage)
+{
+	static const int report_types[] = { HID_INPUT_REPORT, HID_OUTPUT_REPORT,
+					    HID_FEATURE_REPORT };
+	struct hid_report *report;
+	struct hid_field *field;
+	int t;
+
+	for (t = 0; t < ARRAY_SIZE(report_types); t++) {
+		struct list_head *report_list =
+			    &hdev->report_enum[report_types[t]].report_list;
+		list_for_each_entry(report, report_list, list) {
+			if (report->application != application)
+				continue;
+
+			field = appleib_find_report_field(report, field_usage);
+			if (field)
+				return field;
+		}
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(appleib_find_hid_field);
+
+static int appleib_ll_start(struct hid_device *hdev)
+{
+	return 0;
+}
+
+static void appleib_ll_stop(struct hid_device *hdev)
+{
+}
+
+static int appleib_ll_open(struct hid_device *hdev)
+{
+	// TODO: allow event reporting
+	return 0;
+}
+
+static void appleib_ll_close(struct hid_device *hdev)
+{
+	// TODO: disallow event reporting
+}
+
+static int appleib_ll_power(struct hid_device *hdev, int level)
+{
+	struct appleib_hid_dev_info *hdev_info = hdev->driver_data;
+
+	return hid_hw_power(hdev_info->hdev, level);
+}
+
+static int appleib_ll_parse(struct hid_device *hdev)
+{
+	struct appleib_hid_dev_info *hdev_info = hdev->driver_data;
+
+	return hid_parse_report(hdev, hdev_info->hdev->rdesc,
+				hdev_info->hdev->rsize);
+}
+
+static void appleib_ll_request(struct hid_device *hdev,
+			       struct hid_report *report, int reqtype)
+{
+	struct appleib_hid_dev_info *hdev_info = hdev->driver_data;
+
+	hid_hw_request(hdev_info->hdev, report, reqtype);
+}
+
+static int appleib_ll_wait(struct hid_device *hdev)
+{
+	struct appleib_hid_dev_info *hdev_info = hdev->driver_data;
+
+	hid_hw_wait(hdev_info->hdev);
+	return 0;
+}
+
+static int appleib_ll_raw_request(struct hid_device *hdev,
+				  unsigned char reportnum, __u8 *buf,
+				  size_t len, unsigned char rtype, int reqtype)
+{
+	struct appleib_hid_dev_info *hdev_info = hdev->driver_data;
+
+	return hid_hw_raw_request(hdev_info->hdev, reportnum, buf, len, rtype,
+				  reqtype);
+}
+
+static int appleib_ll_output_report(struct hid_device *hdev, __u8 *buf,
+				    size_t len)
+{
+	struct appleib_hid_dev_info *hdev_info = hdev->driver_data;
+
+	return hid_hw_output_report(hdev_info->hdev, buf, len);
+}
+
+static struct hid_ll_driver appleib_ll_driver = {
+	.start = appleib_ll_start,
+	.stop = appleib_ll_stop,
+	.open = appleib_ll_open,
+	.close = appleib_ll_close,
+	.power = appleib_ll_power,
+	.parse = appleib_ll_parse,
+	.request = appleib_ll_request,
+	.wait = appleib_ll_wait,
+	.raw_request = appleib_ll_raw_request,
+	.output_report = appleib_ll_output_report,
+};
+
+static struct hid_device *
+appleib_add_sub_dev(struct appleib_hid_dev_info *hdev_info,
+		    struct hid_device_id *dev_id)
+{
+	struct hid_device *sub_hdev;
+	int rc;
+
+	sub_hdev = hid_allocate_device();
+	if (IS_ERR(sub_hdev))
+		return sub_hdev;
+
+	sub_hdev->dev.parent = &hdev_info->hdev->dev;
+
+	sub_hdev->bus = dev_id->bus;
+	sub_hdev->group = dev_id->group;
+	sub_hdev->vendor = dev_id->vendor;
+	sub_hdev->product = dev_id->product;
+
+	sub_hdev->ll_driver = &appleib_ll_driver;
+
+	snprintf(sub_hdev->name, sizeof(sub_hdev->name),
+		 "iBridge Virtual HID %s/%04x:%04x",
+		 dev_name(sub_hdev->dev.parent), sub_hdev->vendor,
+		 sub_hdev->product);
+
+	sub_hdev->driver_data = hdev_info;
+
+	rc = hid_add_device(sub_hdev);
+	if (rc) {
+		hid_destroy_device(sub_hdev);
+		return ERR_PTR(rc);
+	}
+
+	return sub_hdev;
+}
+
+static struct appleib_hid_dev_info *appleib_add_device(struct hid_device *hdev)
+{
+	struct appleib_hid_dev_info *hdev_info;
+	int i;
+
+	hdev_info = devm_kzalloc(&hdev->dev, sizeof(*hdev_info), GFP_KERNEL);
+	if (!hdev_info)
+		return ERR_PTR(-ENOMEM);
+
+	hdev_info->hdev = hdev;
+
+	for (i = 0; i < ARRAY_SIZE(hdev_info->sub_hdevs); i++) {
+		hdev_info->sub_hdevs[i] =
+			appleib_add_sub_dev(hdev_info, &appleib_sub_hid_ids[i]);
+
+		if (IS_ERR(hdev_info->sub_hdevs[i])) {
+			while (i-- > 0)
+				hid_destroy_device(hdev_info->sub_hdevs[i]);
+			return (void *)hdev_info->sub_hdevs[i];
+		}
+	}
+
+	return hdev_info;
+}
+
+static int appleib_hid_probe(struct hid_device *hdev,
+			     const struct hid_device_id *id)
+{
+	struct appleib_hid_dev_info *hdev_info;
+	struct usb_device *udev;
+	int rc;
+
+	/* check and set usb config first */
+	udev = hid_to_usb_dev(hdev);
+
+	if (udev->actconfig->desc.bConfigurationValue != APPLEIB_BASIC_CONFIG) {
+		rc = usb_driver_set_configuration(udev, APPLEIB_BASIC_CONFIG);
+		return rc ? rc : -ENODEV;
+	}
+
+	rc = hid_parse(hdev);
+	if (rc) {
+		hid_err(hdev, "ib: hid parse failed (%d)\n", rc);
+		goto error;
+	}
+
+	rc = hid_hw_start(hdev, HID_CONNECT_DRIVER);
+	if (rc) {
+		hid_err(hdev, "ib: hw start failed (%d)\n", rc);
+		goto error;
+	}
+
+	hdev_info = appleib_add_device(hdev);
+	if (IS_ERR(hdev_info)) {
+		rc = PTR_ERR(hdev_info);
+		goto stop_hw;
+	}
+
+	hid_set_drvdata(hdev, hdev_info);
+
+	rc = hid_hw_open(hdev);
+	if (rc) {
+		hid_err(hdev, "ib: failed to open hid: %d\n", rc);
+		goto remove_dev;
+	}
+
+	return 0;
+
+remove_dev:
+	appleib_remove_device(hdev);
+stop_hw:
+	hid_hw_stop(hdev);
+error:
+	return rc;
+}
+
+static void appleib_hid_remove(struct hid_device *hdev)
+{
+	hid_hw_close(hdev);
+	appleib_remove_device(hdev);
+	hid_hw_stop(hdev);
+}
+
+static const struct hid_device_id appleib_hid_ids[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_IBRIDGE) },
+	{ },
+};
+
+static struct hid_driver appleib_hid_driver = {
+	.name = "apple-ibridge-hid",
+	.id_table = appleib_hid_ids,
+	.probe = appleib_hid_probe,
+	.remove = appleib_hid_remove,
+	.raw_event = appleib_hid_raw_event,
+#ifdef CONFIG_PM
+	.suspend = appleib_hid_suspend,
+	.resume = appleib_hid_resume,
+	.reset_resume = appleib_hid_reset_resume,
+#endif
+};
+
+static struct appleib_device *appleib_alloc_device(struct acpi_device *acpi_dev)
+{
+	struct appleib_device *ib_dev;
+	acpi_status sts;
+
+	ib_dev = devm_kzalloc(&acpi_dev->dev, sizeof(*ib_dev), GFP_KERNEL);
+	if (!ib_dev)
+		return ERR_PTR(-ENOMEM);
+
+	ib_dev->acpi_dev = acpi_dev;
+
+	/* get iBridge acpi power control method for suspend/resume */
+	sts = acpi_get_handle(acpi_dev->handle, "SOCW", &ib_dev->asoc_socw);
+	if (ACPI_FAILURE(sts)) {
+		dev_err(LOG_DEV(ib_dev),
+			"Error getting handle for ASOC.SOCW method: %s\n",
+			acpi_format_exception(sts));
+		return ERR_PTR(-ENXIO);
+	}
+
+	/* ensure iBridge is powered on */
+	sts = acpi_execute_simple_method(ib_dev->asoc_socw, NULL, 1);
+	if (ACPI_FAILURE(sts))
+		dev_warn(LOG_DEV(ib_dev), "SOCW(1) failed: %s\n",
+			 acpi_format_exception(sts));
+
+	return ib_dev;
+}
+
+static int appleib_probe(struct acpi_device *acpi)
+{
+	struct appleib_device *ib_dev;
+	int ret;
+
+	ib_dev = appleib_alloc_device(acpi);
+	if (IS_ERR(ib_dev))
+		return PTR_ERR(ib_dev);
+
+	ret = hid_register_driver(&appleib_hid_driver);
+	if (ret) {
+		dev_err(LOG_DEV(ib_dev), "Error registering hid driver: %d\n",
+			ret);
+		return ret;
+	}
+
+	acpi->driver_data = ib_dev;
+
+	return 0;
+}
+
+static int appleib_remove(struct acpi_device *acpi)
+{
+	hid_unregister_driver(&appleib_hid_driver);
+
+	return 0;
+}
+
+static int appleib_suspend(struct device *dev)
+{
+	struct appleib_device *ib_dev;
+	int rc;
+
+	ib_dev = acpi_driver_data(to_acpi_device(dev));
+
+	rc = acpi_execute_simple_method(ib_dev->asoc_socw, NULL, 0);
+	if (ACPI_FAILURE(rc))
+		dev_warn(dev, "SOCW(0) failed: %s\n",
+			 acpi_format_exception(rc));
+
+	return 0;
+}
+
+static int appleib_resume(struct device *dev)
+{
+	struct appleib_device *ib_dev;
+	int rc;
+
+	ib_dev = acpi_driver_data(to_acpi_device(dev));
+
+	rc = acpi_execute_simple_method(ib_dev->asoc_socw, NULL, 1);
+	if (ACPI_FAILURE(rc))
+		dev_warn(dev, "SOCW(1) failed: %s\n",
+			 acpi_format_exception(rc));
+
+	return 0;
+}
+
+static const struct dev_pm_ops appleib_pm = {
+	.suspend = appleib_suspend,
+	.resume = appleib_resume,
+	.restore = appleib_resume,
+};
+
+static const struct acpi_device_id appleib_acpi_match[] = {
+	{ "APP7777", 0 },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(acpi, appleib_acpi_match);
+
+static struct acpi_driver appleib_driver = {
+	.name		= "apple-ibridge",
+	.class		= "topcase", /* ? */
+	.owner		= THIS_MODULE,
+	.ids		= appleib_acpi_match,
+	.ops		= {
+		.add		= appleib_probe,
+		.remove		= appleib_remove,
+	},
+	.drv		= {
+		.pm		= &appleib_pm,
+	},
+};
+
+module_acpi_driver(appleib_driver)
+
+MODULE_AUTHOR("Ronald TschalÃr");
+MODULE_DESCRIPTION("Apple iBridge driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index adce58f24f76..f963bb02c477 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -177,6 +177,7 @@
 #define USB_DEVICE_ID_APPLE_IRCONTROL3	0x8241
 #define USB_DEVICE_ID_APPLE_IRCONTROL4	0x8242
 #define USB_DEVICE_ID_APPLE_IRCONTROL5	0x8243
+#define USB_DEVICE_ID_APPLE_IBRIDGE	0x8600
 
 #define USB_VENDOR_ID_ASUS		0x0486
 #define USB_DEVICE_ID_ASUS_T91MT	0x0185
diff --git a/include/linux/apple-ibridge.h b/include/linux/apple-ibridge.h
new file mode 100644
index 000000000000..07ded8c68776
--- /dev/null
+++ b/include/linux/apple-ibridge.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Apple iBridge Driver
+ *
+ * Copyright (c) 2018 Ronald TschalÃr
+ */
+
+#ifndef __LINUX_APPLE_IBRDIGE_H
+#define __LINUX_APPLE_IBRDIGE_H
+
+#include <linux/hid.h>
+
+#define USB_VENDOR_ID_LINUX_FOUNDATION	0x1d6b
+#define USB_DEVICE_ID_IBRIDGE_TB	0x0301
+#define USB_DEVICE_ID_IBRIDGE_ALS	0x0302
+
+struct hid_field *appleib_find_report_field(struct hid_report *report,
+					    unsigned int field_usage);
+struct hid_field *appleib_find_hid_field(struct hid_device *hdev,
+					 unsigned int application,
+					 unsigned int field_usage);
+
+#endif
-- 
2.21.0