hid-elo.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * HID driver for ELO usb touchscreen 4000/4500
 *
 * Copyright (c) 2013 Jiri Slaby
 *
 * Data parsing taken from elousb driver by Vojtech Pavlik.
 */

#include <linux/hid.h>
#include <linux/input.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/workqueue.h>

#include "hid-ids.h"

#define ELO_PERIODIC_READ_INTERVAL	HZ
#define ELO_SMARTSET_CMD_TIMEOUT	2000 /* msec */

/* Elo SmartSet commands */
#define ELO_FLUSH_SMARTSET_RESPONSES	0x02 /* Flush all pending smartset responses */
#define ELO_SEND_SMARTSET_COMMAND	0x05 /* Send a smartset command */
#define ELO_GET_SMARTSET_RESPONSE	0x06 /* Get a smartset response */
#define ELO_DIAG			0x64 /* Diagnostics command */
#define ELO_SMARTSET_PACKET_SIZE	8

struct elo_priv {
	struct usb_device *usbdev;
	struct delayed_work work;
	unsigned char buffer[ELO_SMARTSET_PACKET_SIZE];
};

static struct workqueue_struct *wq;
static bool use_fw_quirk = true;
module_param(use_fw_quirk, bool, S_IRUGO);
MODULE_PARM_DESC(use_fw_quirk, "Do periodic pokes for broken M firmwares (default = true)");

static int elo_input_configured(struct hid_device *hdev,
		struct hid_input *hidinput)
{
	struct input_dev *input = hidinput->input;

	/*
	 * ELO devices have one Button usage in GenDesk field, which makes
	 * hid-input map it to BTN_LEFT; that confuses userspace, which then
	 * considers the device to be a mouse/touchpad instead of touchscreen.
	 */
	clear_bit(BTN_LEFT, input->keybit);
	set_bit(BTN_TOUCH, input->keybit);
	set_bit(ABS_PRESSURE, input->absbit);
	input_set_abs_params(input, ABS_PRESSURE, 0, 256, 0, 0);

	return 0;
}

static void elo_process_data(struct input_dev *input, const u8 *data, int size)
{
	int press;

	input_report_abs(input, ABS_X, (data[3] << 8) | data[2]);
	input_report_abs(input, ABS_Y, (data[5] << 8) | data[4]);

	press = 0;
	if (data[1] & 0x80)
		press = (data[7] << 8) | data[6];
	input_report_abs(input, ABS_PRESSURE, press);

	if (data[1] & 0x03) {
		input_report_key(input, BTN_TOUCH, 1);
		input_sync(input);
	}

	if (data[1] & 0x04)
		input_report_key(input, BTN_TOUCH, 0);

	input_sync(input);
}

static int elo_raw_event(struct hid_device *hdev, struct hid_report *report,
	 u8 *data, int size)
{
	struct hid_input *hidinput;

	if (!(hdev->claimed & HID_CLAIMED_INPUT) || list_empty(&hdev->inputs))
		return 0;

	hidinput = list_first_entry(&hdev->inputs, struct hid_input, list);

	switch (report->id) {
	case 0:
		if (data[0] == 'T') {	/* Mandatory ELO packet marker */
			elo_process_data(hidinput->input, data, size);
			return 1;
		}
		break;
	default:	/* unknown report */
		/* Unknown report type; pass upstream */
		hid_info(hdev, "unknown report type %d\n", report->id);
		break;
	}

	return 0;
}

static int elo_smartset_send_get(struct usb_device *dev, u8 command,
		void *data)
{
	unsigned int pipe;
	u8 dir;

	if (command == ELO_SEND_SMARTSET_COMMAND) {
		pipe = usb_sndctrlpipe(dev, 0);
		dir = USB_DIR_OUT;
	} else if (command == ELO_GET_SMARTSET_RESPONSE) {
		pipe = usb_rcvctrlpipe(dev, 0);
		dir = USB_DIR_IN;
	} else
		return -EINVAL;

	return usb_control_msg(dev, pipe, command,
			dir | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
			0, 0, data, ELO_SMARTSET_PACKET_SIZE,
			ELO_SMARTSET_CMD_TIMEOUT);
}

static int elo_flush_smartset_responses(struct usb_device *dev)
{
	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
			ELO_FLUSH_SMARTSET_RESPONSES,
			USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
			0, 0, NULL, 0, USB_CTRL_SET_TIMEOUT);
}

static void elo_work(struct work_struct *work)
{
	struct elo_priv *priv = container_of(work, struct elo_priv, work.work);
	struct usb_device *dev = priv->usbdev;
	unsigned char *buffer = priv->buffer;
	int ret;

	ret = elo_flush_smartset_responses(dev);
	if (ret < 0) {
		dev_err(&dev->dev, "initial FLUSH_SMARTSET_RESPONSES failed, error %d\n",
				ret);
		goto fail;
	}

	/* send Diagnostics command */
	*buffer = ELO_DIAG;
	ret = elo_smartset_send_get(dev, ELO_SEND_SMARTSET_COMMAND, buffer);
	if (ret < 0) {
		dev_err(&dev->dev, "send Diagnostics Command failed, error %d\n",
				ret);
		goto fail;
	}

	/* get the result */
	ret = elo_smartset_send_get(dev, ELO_GET_SMARTSET_RESPONSE, buffer);
	if (ret < 0) {
		dev_err(&dev->dev, "get Diagnostics Command response failed, error %d\n",
				ret);
		goto fail;
	}

	/* read the ack */
	if (*buffer != 'A') {
		ret = elo_smartset_send_get(dev, ELO_GET_SMARTSET_RESPONSE,
				buffer);
		if (ret < 0) {
			dev_err(&dev->dev, "get acknowledge response failed, error %d\n",
					ret);
			goto fail;
		}
	}

fail:
	ret = elo_flush_smartset_responses(dev);
	if (ret < 0)
		dev_err(&dev->dev, "final FLUSH_SMARTSET_RESPONSES failed, error %d\n",
				ret);
	queue_delayed_work(wq, &priv->work, ELO_PERIODIC_READ_INTERVAL);
}

/*
 * Not all Elo devices need the periodic HID descriptor reads.
 * Only firmware version M needs this.
 */
static bool elo_broken_firmware(struct usb_device *dev)
{
	struct usb_device *hub = dev->parent;
	struct usb_device *child = NULL;
	u16 fw_lvl = le16_to_cpu(dev->descriptor.bcdDevice);
	u16 child_vid, child_pid;
	int i;
    
	if (!use_fw_quirk)
		return false;
	if (fw_lvl != 0x10d)
		return false;

	/* iterate sibling devices of the touch controller */
	usb_hub_for_each_child(hub, i, child) {
		child_vid = le16_to_cpu(child->descriptor.idVendor);
		child_pid = le16_to_cpu(child->descriptor.idProduct);

		/*
		 * If one of the devices below is present attached as a sibling of 
		 * the touch controller then  this is a newer IBM 4820 monitor that 
		 * does not need the IBM-requested workaround if fw level is
		 * 0x010d - aka 'M'.
		 * No other HW can have this combination.
		 */
		if (child_vid==0x04b3) {
			switch (child_pid) {
			case 0x4676: /* 4820 21x Video */
			case 0x4677: /* 4820 51x Video */
			case 0x4678: /* 4820 2Lx Video */
			case 0x4679: /* 4820 5Lx Video */
				return false;
			}
		}
	}
	return true;
}

static int elo_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
	struct elo_priv *priv;
	int ret;

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	INIT_DELAYED_WORK(&priv->work, elo_work);
	priv->usbdev = interface_to_usbdev(to_usb_interface(hdev->dev.parent));

	hid_set_drvdata(hdev, priv);

	ret = hid_parse(hdev);
	if (ret) {
		hid_err(hdev, "parse failed\n");
		goto err_free;
	}

	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
	if (ret) {
		hid_err(hdev, "hw start failed\n");
		goto err_free;
	}

	if (elo_broken_firmware(priv->usbdev)) {
		hid_info(hdev, "broken firmware found, installing workaround\n");
		queue_delayed_work(wq, &priv->work, ELO_PERIODIC_READ_INTERVAL);
	}

	return 0;
err_free:
	kfree(priv);
	return ret;
}

static void elo_remove(struct hid_device *hdev)
{
	struct elo_priv *priv = hid_get_drvdata(hdev);

	hid_hw_stop(hdev);
	cancel_delayed_work_sync(&priv->work);
	kfree(priv);
}

static const struct hid_device_id elo_devices[] = {
	{ HID_USB_DEVICE(USB_VENDOR_ID_ELO, 0x0009), },
	{ HID_USB_DEVICE(USB_VENDOR_ID_ELO, 0x0030), },
	{ }
};
MODULE_DEVICE_TABLE(hid, elo_devices);

static struct hid_driver elo_driver = {
	.name = "elo",
	.id_table = elo_devices,
	.probe = elo_probe,
	.remove = elo_remove,
	.raw_event = elo_raw_event,
	.input_configured = elo_input_configured,
};

static int __init elo_driver_init(void)
{
	int ret;

	wq = create_singlethread_workqueue("elousb");
	if (!wq)
		return -ENOMEM;

	ret = hid_register_driver(&elo_driver);
	if (ret)
		destroy_workqueue(wq);

	return ret;
}
module_init(elo_driver_init);

static void __exit elo_driver_exit(void)
{
	hid_unregister_driver(&elo_driver);
	destroy_workqueue(wq);
}
module_exit(elo_driver_exit);

MODULE_AUTHOR("Jiri Slaby <jslaby@suse.cz>");
MODULE_LICENSE("GPL");