1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * EETI Egalax serial touchscreen driver
  4 *
  5 * Copyright (c) 2015 Zoltán Böszörményi <zboszor@pr.hu>
  6 *
  7 * based on the
  8 *
  9 * Hampshire serial touchscreen driver (Copyright (c) 2010 Adam Bennett)
 10 */
 11
 12
 13#include <linux/errno.h>
 14#include <linux/kernel.h>
 15#include <linux/module.h>
 16#include <linux/slab.h>
 17#include <linux/input.h>
 18#include <linux/serio.h>
 19
 20#define DRIVER_DESC	"EETI Egalax serial touchscreen driver"
 21
 22/*
 23 * Definitions & global arrays.
 24 */
 25
 26#define EGALAX_FORMAT_MAX_LENGTH	6
 27#define EGALAX_FORMAT_START_BIT		BIT(7)
 28#define EGALAX_FORMAT_PRESSURE_BIT	BIT(6)
 29#define EGALAX_FORMAT_TOUCH_BIT		BIT(0)
 30#define EGALAX_FORMAT_RESOLUTION_MASK	0x06
 31
 32#define EGALAX_MIN_XC			0
 33#define EGALAX_MAX_XC			0x4000
 34#define EGALAX_MIN_YC			0
 35#define EGALAX_MAX_YC			0x4000
 36
 37/*
 38 * Per-touchscreen data.
 39 */
 40struct egalax {
 41	struct input_dev *input;
 42	struct serio *serio;
 43	int idx;
 44	u8 data[EGALAX_FORMAT_MAX_LENGTH];
 45	char phys[32];
 46};
 47
 48static void egalax_process_data(struct egalax *egalax)
 49{
 50	struct input_dev *dev = egalax->input;
 51	u8 *data = egalax->data;
 52	u16 x, y;
 53	u8 shift;
 54	u8 mask;
 55
 56	shift = 3 - ((data[0] & EGALAX_FORMAT_RESOLUTION_MASK) >> 1);
 57	mask = 0xff >> (shift + 1);
 58
 59	x = (((u16)(data[1] & mask) << 7) | (data[2] & 0x7f)) << shift;
 60	y = (((u16)(data[3] & mask) << 7) | (data[4] & 0x7f)) << shift;
 61
 62	input_report_key(dev, BTN_TOUCH, data[0] & EGALAX_FORMAT_TOUCH_BIT);
 63	input_report_abs(dev, ABS_X, x);
 64	input_report_abs(dev, ABS_Y, y);
 65	input_sync(dev);
 66}
 67
 68static irqreturn_t egalax_interrupt(struct serio *serio,
 69				    unsigned char data, unsigned int flags)
 70{
 71	struct egalax *egalax = serio_get_drvdata(serio);
 72	int pkt_len;
 73
 74	egalax->data[egalax->idx++] = data;
 75
 76	if (likely(egalax->data[0] & EGALAX_FORMAT_START_BIT)) {
 77		pkt_len = egalax->data[0] & EGALAX_FORMAT_PRESSURE_BIT ? 6 : 5;
 78		if (pkt_len == egalax->idx) {
 79			egalax_process_data(egalax);
 80			egalax->idx = 0;
 81		}
 82	} else {
 83		dev_dbg(&serio->dev, "unknown/unsynchronized data: %x\n",
 84			egalax->data[0]);
 85		egalax->idx = 0;
 86	}
 87
 88	return IRQ_HANDLED;
 89}
 90
 91/*
 92 * egalax_connect() is the routine that is called when someone adds a
 93 * new serio device that supports egalax protocol and registers it as
 94 * an input device. This is usually accomplished using inputattach.
 95 */
 96static int egalax_connect(struct serio *serio, struct serio_driver *drv)
 97{
 98	struct egalax *egalax;
 99	struct input_dev *input_dev;
100	int error;
101
102	egalax = kzalloc(sizeof(*egalax), GFP_KERNEL);
103	input_dev = input_allocate_device();
104	if (!egalax || !input_dev) {
105		error = -ENOMEM;
106		goto err_free_mem;
107	}
108
109	egalax->serio = serio;
110	egalax->input = input_dev;
111	snprintf(egalax->phys, sizeof(egalax->phys),
112		 "%s/input0", serio->phys);
113
114	input_dev->name = "EETI eGalaxTouch Serial TouchScreen";
115	input_dev->phys = egalax->phys;
116	input_dev->id.bustype = BUS_RS232;
117	input_dev->id.vendor = SERIO_EGALAX;
118	input_dev->id.product = 0;
119	input_dev->id.version = 0x0001;
120	input_dev->dev.parent = &serio->dev;
121
122	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
123	input_set_abs_params(input_dev, ABS_X,
124			     EGALAX_MIN_XC, EGALAX_MAX_XC, 0, 0);
125	input_set_abs_params(input_dev, ABS_Y,
126			     EGALAX_MIN_YC, EGALAX_MAX_YC, 0, 0);
127
128	serio_set_drvdata(serio, egalax);
129
130	error = serio_open(serio, drv);
131	if (error)
132		goto err_reset_drvdata;
133
134	error = input_register_device(input_dev);
135	if (error)
136		goto err_close_serio;
137
138	return 0;
139
140err_close_serio:
141	serio_close(serio);
142err_reset_drvdata:
143	serio_set_drvdata(serio, NULL);
144err_free_mem:
145	input_free_device(input_dev);
146	kfree(egalax);
147	return error;
148}
149
150static void egalax_disconnect(struct serio *serio)
151{
152	struct egalax *egalax = serio_get_drvdata(serio);
153
154	serio_close(serio);
155	serio_set_drvdata(serio, NULL);
156	input_unregister_device(egalax->input);
157	kfree(egalax);
158}
159
160/*
161 * The serio driver structure.
162 */
163
164static const struct serio_device_id egalax_serio_ids[] = {
165	{
166		.type	= SERIO_RS232,
167		.proto	= SERIO_EGALAX,
168		.id	= SERIO_ANY,
169		.extra	= SERIO_ANY,
170	},
171	{ 0 }
172};
173
174MODULE_DEVICE_TABLE(serio, egalax_serio_ids);
175
176static struct serio_driver egalax_drv = {
177	.driver		= {
178		.name	= "egalax",
179	},
180	.description	= DRIVER_DESC,
181	.id_table	= egalax_serio_ids,
182	.interrupt	= egalax_interrupt,
183	.connect	= egalax_connect,
184	.disconnect	= egalax_disconnect,
185};
186module_serio_driver(egalax_drv);
187
188MODULE_AUTHOR("Zoltán Böszörményi <zboszor@pr.hu>");
189MODULE_DESCRIPTION(DRIVER_DESC);
190MODULE_LICENSE("GPL v2");