// SPDX-License-Identifier: GPL-2.0-only
/*
 * Penmount serial touchscreen driver
 *
 * Copyright (c) 2006 Rick Koch <n1gp@hotmail.com>
 * Copyright (c) 2011 John Sung <penmount.touch@gmail.com>
 *
 * Based on ELO driver (drivers/input/touchscreen/elo.c)
 * Copyright (c) 2004 Vojtech Pavlik
 */


#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/input/mt.h>
#include <linux/serio.h>

#define DRIVER_DESC	"PenMount serial touchscreen driver"

MODULE_AUTHOR("Rick Koch <n1gp@hotmail.com>");
MODULE_AUTHOR("John Sung <penmount.touch@gmail.com>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */

#define	PM_MAX_LENGTH	6
#define	PM_MAX_MTSLOT	16
#define	PM_3000_MTSLOT	2
#define	PM_6250_MTSLOT	12

/*
 * Multi-touch slot
 */

struct mt_slot {
	unsigned short x, y;
	bool active; /* is the touch valid? */
};

/*
 * Per-touchscreen data.
 */

struct pm {
	struct input_dev *dev;
	struct serio *serio;
	int idx;
	unsigned char data[PM_MAX_LENGTH];
	char phys[32];
	unsigned char packetsize;
	unsigned char maxcontacts;
	struct mt_slot slots[PM_MAX_MTSLOT];
	void (*parse_packet)(struct pm *);
};

/*
 * pm_mtevent() sends mt events and also emulates pointer movement
 */

static void pm_mtevent(struct pm *pm, struct input_dev *input)
{
	int i;

	for (i = 0; i < pm->maxcontacts; ++i) {
		input_mt_slot(input, i);
		input_mt_report_slot_state(input, MT_TOOL_FINGER,
				pm->slots[i].active);
		if (pm->slots[i].active) {
			input_event(input, EV_ABS, ABS_MT_POSITION_X, pm->slots[i].x);
			input_event(input, EV_ABS, ABS_MT_POSITION_Y, pm->slots[i].y);
		}
	}

	input_mt_report_pointer_emulation(input, true);
	input_sync(input);
}

/*
 * pm_checkpacket() checks if data packet is valid
 */

static bool pm_checkpacket(unsigned char *packet)
{
	int total = 0;
	int i;

	for (i = 0; i < 5; i++)
		total += packet[i];

	return packet[5] == (unsigned char)~(total & 0xff);
}

static void pm_parse_9000(struct pm *pm)
{
	struct input_dev *dev = pm->dev;

	if ((pm->data[0] & 0x80) && pm->packetsize == ++pm->idx) {
		input_report_abs(dev, ABS_X, pm->data[1] * 128 + pm->data[2]);
		input_report_abs(dev, ABS_Y, pm->data[3] * 128 + pm->data[4]);
		input_report_key(dev, BTN_TOUCH, !!(pm->data[0] & 0x40));
		input_sync(dev);
		pm->idx = 0;
	}
}

static void pm_parse_6000(struct pm *pm)
{
	struct input_dev *dev = pm->dev;

	if ((pm->data[0] & 0xbf) == 0x30 && pm->packetsize == ++pm->idx) {
		if (pm_checkpacket(pm->data)) {
			input_report_abs(dev, ABS_X,
					pm->data[2] * 256 + pm->data[1]);
			input_report_abs(dev, ABS_Y,
					pm->data[4] * 256 + pm->data[3]);
			input_report_key(dev, BTN_TOUCH, pm->data[0] & 0x40);
			input_sync(dev);
		}
		pm->idx = 0;
	}
}

static void pm_parse_3000(struct pm *pm)
{
	struct input_dev *dev = pm->dev;

	if ((pm->data[0] & 0xce) == 0x40 && pm->packetsize == ++pm->idx) {
		if (pm_checkpacket(pm->data)) {
			int slotnum = pm->data[0] & 0x0f;
			pm->slots[slotnum].active = pm->data[0] & 0x30;
			pm->slots[slotnum].x = pm->data[2] * 256 + pm->data[1];
			pm->slots[slotnum].y = pm->data[4] * 256 + pm->data[3];
			pm_mtevent(pm, dev);
		}
		pm->idx = 0;
	}
}

static void pm_parse_6250(struct pm *pm)
{
	struct input_dev *dev = pm->dev;

	if ((pm->data[0] & 0xb0) == 0x30 && pm->packetsize == ++pm->idx) {
		if (pm_checkpacket(pm->data)) {
			int slotnum = pm->data[0] & 0x0f;
			pm->slots[slotnum].active = pm->data[0] & 0x40;
			pm->slots[slotnum].x = pm->data[2] * 256 + pm->data[1];
			pm->slots[slotnum].y = pm->data[4] * 256 + pm->data[3];
			pm_mtevent(pm, dev);
		}
		pm->idx = 0;
	}
}

static irqreturn_t pm_interrupt(struct serio *serio,
		unsigned char data, unsigned int flags)
{
	struct pm *pm = serio_get_drvdata(serio);

	pm->data[pm->idx] = data;

	pm->parse_packet(pm);

	return IRQ_HANDLED;
}

/*
 * pm_disconnect() is the opposite of pm_connect()
 */

static void pm_disconnect(struct serio *serio)
{
	struct pm *pm = serio_get_drvdata(serio);

	serio_close(serio);

	input_unregister_device(pm->dev);
	kfree(pm);

	serio_set_drvdata(serio, NULL);
}

/*
 * pm_connect() is the routine that is called when someone adds a
 * new serio device that supports PenMount protocol and registers it as
 * an input device.
 */

static int pm_connect(struct serio *serio, struct serio_driver *drv)
{
	struct pm *pm;
	struct input_dev *input_dev;
	int max_x, max_y;
	int err;

	pm = kzalloc(sizeof(*pm), GFP_KERNEL);
	input_dev = input_allocate_device();
	if (!pm || !input_dev) {
		err = -ENOMEM;
		goto fail1;
	}

	pm->serio = serio;
	pm->dev = input_dev;
	snprintf(pm->phys, sizeof(pm->phys), "%s/input0", serio->phys);
	pm->maxcontacts = 1;

	input_dev->name = "PenMount Serial TouchScreen";
	input_dev->phys = pm->phys;
	input_dev->id.bustype = BUS_RS232;
	input_dev->id.vendor = SERIO_PENMOUNT;
	input_dev->id.product = 0;
	input_dev->id.version = 0x0100;
	input_dev->dev.parent = &serio->dev;

	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

	switch (serio->id.id) {
	default:
	case 0:
		pm->packetsize = 5;
		pm->parse_packet = pm_parse_9000;
		input_dev->id.product = 0x9000;
		max_x = max_y = 0x3ff;
		break;

	case 1:
		pm->packetsize = 6;
		pm->parse_packet = pm_parse_6000;
		input_dev->id.product = 0x6000;
		max_x = max_y = 0x3ff;
		break;

	case 2:
		pm->packetsize = 6;
		pm->parse_packet = pm_parse_3000;
		input_dev->id.product = 0x3000;
		max_x = max_y = 0x7ff;
		pm->maxcontacts = PM_3000_MTSLOT;
		break;

	case 3:
		pm->packetsize = 6;
		pm->parse_packet = pm_parse_6250;
		input_dev->id.product = 0x6250;
		max_x = max_y = 0x3ff;
		pm->maxcontacts = PM_6250_MTSLOT;
		break;
	}

	input_set_abs_params(pm->dev, ABS_X, 0, max_x, 0, 0);
	input_set_abs_params(pm->dev, ABS_Y, 0, max_y, 0, 0);

	if (pm->maxcontacts > 1) {
		input_mt_init_slots(pm->dev, pm->maxcontacts, 0);
		input_set_abs_params(pm->dev,
				     ABS_MT_POSITION_X, 0, max_x, 0, 0);
		input_set_abs_params(pm->dev,
				     ABS_MT_POSITION_Y, 0, max_y, 0, 0);
	}

	serio_set_drvdata(serio, pm);

	err = serio_open(serio, drv);
	if (err)
		goto fail2;

	err = input_register_device(pm->dev);
	if (err)
		goto fail3;

	return 0;

 fail3:	serio_close(serio);
 fail2:	serio_set_drvdata(serio, NULL);
 fail1:	input_free_device(input_dev);
	kfree(pm);
	return err;
}

/*
 * The serio driver structure.
 */

static const struct serio_device_id pm_serio_ids[] = {
	{
		.type	= SERIO_RS232,
		.proto	= SERIO_PENMOUNT,
		.id	= SERIO_ANY,
		.extra	= SERIO_ANY,
	},
	{ 0 }
};

MODULE_DEVICE_TABLE(serio, pm_serio_ids);

static struct serio_driver pm_drv = {
	.driver		= {
		.name	= "serio-penmount",
	},
	.description	= DRIVER_DESC,
	.id_table	= pm_serio_ids,
	.interrupt	= pm_interrupt,
	.connect	= pm_connect,
	.disconnect	= pm_disconnect,
};

module_serio_driver(pm_drv);