1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Fujitsu serial touchscreen driver
4 *
5 * Copyright (c) Dmitry Torokhov <dtor@mail.ru>
6 */
7
8
9#include <linux/errno.h>
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/slab.h>
13#include <linux/input.h>
14#include <linux/serio.h>
15
16#define DRIVER_DESC	"Fujitsu serial touchscreen driver"
17
18MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
19MODULE_DESCRIPTION(DRIVER_DESC);
20MODULE_LICENSE("GPL");
21
22#define FUJITSU_LENGTH 5
23
24/*
25 * Per-touchscreen data.
26 */
27struct fujitsu {
28	struct input_dev *dev;
29	struct serio *serio;
30	int idx;
31	unsigned char data[FUJITSU_LENGTH];
32	char phys[32];
33};
34
35/*
36 * Decode serial data (5 bytes per packet)
37 * First byte
38 * 1 C 0 0 R S S S
39 * Where C is 1 while in calibration mode (which we don't use)
40 * R is 1 when no coordinate corection was done.
41 * S are button state
42 */
43static irqreturn_t fujitsu_interrupt(struct serio *serio,
44				     unsigned char data, unsigned int flags)
45{
46	struct fujitsu *fujitsu = serio_get_drvdata(serio);
47	struct input_dev *dev = fujitsu->dev;
48
49	if (fujitsu->idx == 0) {
50		/* resync skip until start of frame */
51		if ((data & 0xf0) != 0x80)
52			return IRQ_HANDLED;
53	} else {
54		/* resync skip garbage */
55		if (data & 0x80) {
56			fujitsu->idx = 0;
57			return IRQ_HANDLED;
58		}
59	}
60
61	fujitsu->data[fujitsu->idx++] = data;
62	if (fujitsu->idx == FUJITSU_LENGTH) {
63		input_report_abs(dev, ABS_X,
64				 (fujitsu->data[2] << 7) | fujitsu->data[1]);
65		input_report_abs(dev, ABS_Y,
66				 (fujitsu->data[4] << 7) | fujitsu->data[3]);
67		input_report_key(dev, BTN_TOUCH,
68				 (fujitsu->data[0] & 0x03) != 2);
69		input_sync(dev);
70		fujitsu->idx = 0;
71	}
72
73	return IRQ_HANDLED;
74}
75
76/*
77 * fujitsu_disconnect() is the opposite of fujitsu_connect()
78 */
79static void fujitsu_disconnect(struct serio *serio)
80{
81	struct fujitsu *fujitsu = serio_get_drvdata(serio);
82
83	input_get_device(fujitsu->dev);
84	input_unregister_device(fujitsu->dev);
85	serio_close(serio);
86	serio_set_drvdata(serio, NULL);
87	input_put_device(fujitsu->dev);
88	kfree(fujitsu);
89}
90
91/*
92 * fujitsu_connect() is the routine that is called when someone adds a
93 * new serio device that supports the Fujitsu protocol and registers it
94 * as input device.
95 */
96static int fujitsu_connect(struct serio *serio, struct serio_driver *drv)
97{
98	struct fujitsu *fujitsu;
99	struct input_dev *input_dev;
100	int err;
101
102	fujitsu = kzalloc(sizeof(struct fujitsu), GFP_KERNEL);
103	input_dev = input_allocate_device();
104	if (!fujitsu || !input_dev) {
105		err = -ENOMEM;
106		goto fail1;
107	}
108
109	fujitsu->serio = serio;
110	fujitsu->dev = input_dev;
111	snprintf(fujitsu->phys, sizeof(fujitsu->phys),
112		 "%s/input0", serio->phys);
113
114	input_dev->name = "Fujitsu Serial Touchscreen";
115	input_dev->phys = fujitsu->phys;
116	input_dev->id.bustype = BUS_RS232;
117	input_dev->id.vendor = SERIO_FUJITSU;
118	input_dev->id.product = 0;
119	input_dev->id.version = 0x0100;
120	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
121	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
122
123	input_set_abs_params(input_dev, ABS_X, 0, 4096, 0, 0);
124	input_set_abs_params(input_dev, ABS_Y, 0, 4096, 0, 0);
125	serio_set_drvdata(serio, fujitsu);
126
127	err = serio_open(serio, drv);
128	if (err)
129		goto fail2;
130
131	err = input_register_device(fujitsu->dev);
132	if (err)
133		goto fail3;
134
135	return 0;
136
137 fail3:
138	serio_close(serio);
139 fail2:
140	serio_set_drvdata(serio, NULL);
141 fail1:
142	input_free_device(input_dev);
143	kfree(fujitsu);
144	return err;
145}
146
147/*
148 * The serio driver structure.
149 */
150static const struct serio_device_id fujitsu_serio_ids[] = {
151	{
152		.type	= SERIO_RS232,
153		.proto	= SERIO_FUJITSU,
154		.id	= SERIO_ANY,
155		.extra	= SERIO_ANY,
156	},
157	{ 0 }
158};
159
160MODULE_DEVICE_TABLE(serio, fujitsu_serio_ids);
161
162static struct serio_driver fujitsu_drv = {
163	.driver		= {
164		.name	= "fujitsu_ts",
165	},
166	.description	= DRIVER_DESC,
167	.id_table	= fujitsu_serio_ids,
168	.interrupt	= fujitsu_interrupt,
169	.connect	= fujitsu_connect,
170	.disconnect	= fujitsu_disconnect,
171};
172
173module_serio_driver(fujitsu_drv);
174