// SPDX-License-Identifier: GPL-2.0-only/* * TSC-40 serial touchscreen driver. It should be compatible with * TSC-10 and 25. * * Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> */ #include <linux/kernel.h>#include <linux/module.h>#include <linux/slab.h>#include <linux/input.h>#include <linux/serio.h> #define PACKET_LENGTH  5struct tsc_ser {	struct input_dev *dev;	struct serio *serio;	u32 idx;	unsigned char data[PACKET_LENGTH];	char phys[32];}; static void tsc_process_data(struct tsc_ser *ptsc){	struct input_dev *dev = ptsc->dev;	u8 *data = ptsc->data;	u32 x;	u32 y; 	x = ((data[1] & 0x03) << 8) | data[2];	y = ((data[3] & 0x03) << 8) | data[4]; 	input_report_abs(dev, ABS_X, x);	input_report_abs(dev, ABS_Y, y);	input_report_key(dev, BTN_TOUCH, 1); 	input_sync(dev);} static irqreturn_t tsc_interrupt(struct serio *serio,		unsigned char data, unsigned int flags){	struct tsc_ser *ptsc = serio_get_drvdata(serio);	struct input_dev *dev = ptsc->dev; 	ptsc->data[ptsc->idx] = data;	switch (ptsc->idx++) {	case 0:		if (unlikely((data & 0x3e) != 0x10)) {			dev_dbg(&serio->dev,				"unsynchronized packet start (0x%02x)\n", data);			ptsc->idx = 0;		} else if (!(data & 0x01)) {			input_report_key(dev, BTN_TOUCH, 0);			input_sync(dev);			ptsc->idx = 0;		}		break; 	case 1:	case 3:		if (unlikely(data & 0xfc)) {			dev_dbg(&serio->dev,				"unsynchronized data 0x%02x at offset %d\n",				data, ptsc->idx - 1);			ptsc->idx = 0;		}		break; 	case 4:		tsc_process_data(ptsc);		ptsc->idx = 0;		break;	} 	return IRQ_HANDLED;} static int tsc_connect(struct serio *serio, struct serio_driver *drv){	struct tsc_ser *ptsc;	struct input_dev *input_dev;	int error; 	ptsc = kzalloc_obj(*ptsc);	input_dev = input_allocate_device();	if (!ptsc || !input_dev) {		error = -ENOMEM;		goto fail1;	} 	ptsc->serio = serio;	ptsc->dev = input_dev;	scnprintf(ptsc->phys, sizeof(ptsc->phys), "%s/input0", serio->phys); 	input_dev->name = "TSC-10/25/40 Serial TouchScreen";	input_dev->phys = ptsc->phys;	input_dev->id.bustype = BUS_RS232;	input_dev->id.vendor = SERIO_TSC40;	input_dev->id.product = 40;	input_dev->id.version = 0x0001;	input_dev->dev.parent = &serio->dev; 	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);	__set_bit(BTN_TOUCH, input_dev->keybit);	input_set_abs_params(ptsc->dev, ABS_X, 0, 0x3ff, 0, 0);	input_set_abs_params(ptsc->dev, ABS_Y, 0, 0x3ff, 0, 0); 	serio_set_drvdata(serio, ptsc); 	error = serio_open(serio, drv);	if (error)		goto fail2; 	error = input_register_device(ptsc->dev);	if (error)		goto fail3; 	return 0; fail3:	serio_close(serio);fail2:	serio_set_drvdata(serio, NULL);fail1:	input_free_device(input_dev);	kfree(ptsc);	return error;} static void tsc_disconnect(struct serio *serio){	struct tsc_ser *ptsc = serio_get_drvdata(serio); 	serio_close(serio); 	input_unregister_device(ptsc->dev);	kfree(ptsc); 	serio_set_drvdata(serio, NULL);} static const struct serio_device_id tsc_serio_ids[] = {	{		.type   = SERIO_RS232,		.proto  = SERIO_TSC40,		.id     = SERIO_ANY,		.extra  = SERIO_ANY,	},	{ 0 }};MODULE_DEVICE_TABLE(serio, tsc_serio_ids); #define DRIVER_DESC    "TSC-10/25/40 serial touchscreen driver" static struct serio_driver tsc_drv = {	.driver	= {		.name   = "tsc40",	},	.description    = DRIVER_DESC,	.id_table	= tsc_serio_ids,	.interrupt      = tsc_interrupt,	.connect	= tsc_connect,	.disconnect     = tsc_disconnect,}; module_serio_driver(tsc_drv); MODULE_AUTHOR("Sebastian Andrzej Siewior <bigeasy@linutronix.de>");MODULE_DESCRIPTION(DRIVER_DESC);MODULE_LICENSE("GPL v2");