1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * EETI Egalax serial touchscreen driver
4 *
5 * Copyright (c) 2015 Zolt��n B��sz��rm��nyi <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(struct 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("Zolt��n B��sz��rm��nyi <zboszor@pr.hu>");
189MODULE_DESCRIPTION(DRIVER_DESC);
190MODULE_LICENSE("GPL v2");
191