1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Hampshire serial touchscreen driver
4  *
5  * Copyright (c) 2010 Adam Bennett
6  * Based on the dynapro driver (c) Tias Guns
7  */
8 
9 
10 /*
11  * 2010/04/08 Adam Bennett <abennett72@gmail.com>
12  *   Copied dynapro.c and edited for Hampshire 4-byte protocol
13  */
14 
15 #include <linux/errno.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/slab.h>
19 #include <linux/input.h>
20 #include <linux/serio.h>
21 
22 #define DRIVER_DESC	"Hampshire serial touchscreen driver"
23 
24 MODULE_AUTHOR("Adam Bennett <abennett72@gmail.com>");
25 MODULE_DESCRIPTION(DRIVER_DESC);
26 MODULE_LICENSE("GPL");
27 
28 /*
29  * Definitions & global arrays.
30  */
31 
32 #define HAMPSHIRE_FORMAT_TOUCH_BIT 0x40
33 #define HAMPSHIRE_FORMAT_LENGTH 4
34 #define HAMPSHIRE_RESPONSE_BEGIN_BYTE 0x80
35 
36 #define HAMPSHIRE_MIN_XC 0
37 #define HAMPSHIRE_MAX_XC 0x1000
38 #define HAMPSHIRE_MIN_YC 0
39 #define HAMPSHIRE_MAX_YC 0x1000
40 
41 #define HAMPSHIRE_GET_XC(data) (((data[3] & 0x0c) >> 2) | (data[1] << 2) | ((data[0] & 0x38) << 6))
42 #define HAMPSHIRE_GET_YC(data) ((data[3] & 0x03) | (data[2] << 2) | ((data[0] & 0x07) << 9))
43 #define HAMPSHIRE_GET_TOUCHED(data) (HAMPSHIRE_FORMAT_TOUCH_BIT & data[0])
44 
45 /*
46  * Per-touchscreen data.
47  */
48 
49 struct hampshire {
50 	struct input_dev *dev;
51 	struct serio *serio;
52 	int idx;
53 	unsigned char data[HAMPSHIRE_FORMAT_LENGTH];
54 	char phys[32];
55 };
56 
57 static void hampshire_process_data(struct hampshire *phampshire)
58 {
59 	struct input_dev *dev = phampshire->dev;
60 
61 	if (HAMPSHIRE_FORMAT_LENGTH == ++phampshire->idx) {
62 		input_report_abs(dev, ABS_X, HAMPSHIRE_GET_XC(phampshire->data));
63 		input_report_abs(dev, ABS_Y, HAMPSHIRE_GET_YC(phampshire->data));
64 		input_report_key(dev, BTN_TOUCH,
65 				 HAMPSHIRE_GET_TOUCHED(phampshire->data));
66 		input_sync(dev);
67 
68 		phampshire->idx = 0;
69 	}
70 }
71 
72 static irqreturn_t hampshire_interrupt(struct serio *serio,
73 		unsigned char data, unsigned int flags)
74 {
75 	struct hampshire *phampshire = serio_get_drvdata(serio);
76 
77 	phampshire->data[phampshire->idx] = data;
78 
79 	if (HAMPSHIRE_RESPONSE_BEGIN_BYTE & phampshire->data[0])
80 		hampshire_process_data(phampshire);
81 	else
82 		dev_dbg(&serio->dev, "unknown/unsynchronized data: %x\n",
83 			phampshire->data[0]);
84 
85 	return IRQ_HANDLED;
86 }
87 
88 static void hampshire_disconnect(struct serio *serio)
89 {
90 	struct hampshire *phampshire = serio_get_drvdata(serio);
91 
92 	input_get_device(phampshire->dev);
93 	input_unregister_device(phampshire->dev);
94 	serio_close(serio);
95 	serio_set_drvdata(serio, NULL);
96 	input_put_device(phampshire->dev);
97 	kfree(phampshire);
98 }
99 
100 /*
101  * hampshire_connect() is the routine that is called when someone adds a
102  * new serio device that supports hampshire protocol and registers it as
103  * an input device. This is usually accomplished using inputattach.
104  */
105 
106 static int hampshire_connect(struct serio *serio, struct serio_driver *drv)
107 {
108 	struct hampshire *phampshire;
109 	struct input_dev *input_dev;
110 	int err;
111 
112 	phampshire = kzalloc(sizeof(struct hampshire), GFP_KERNEL);
113 	input_dev = input_allocate_device();
114 	if (!phampshire || !input_dev) {
115 		err = -ENOMEM;
116 		goto fail1;
117 	}
118 
119 	phampshire->serio = serio;
120 	phampshire->dev = input_dev;
121 	snprintf(phampshire->phys, sizeof(phampshire->phys),
122 		 "%s/input0", serio->phys);
123 
124 	input_dev->name = "Hampshire Serial TouchScreen";
125 	input_dev->phys = phampshire->phys;
126 	input_dev->id.bustype = BUS_RS232;
127 	input_dev->id.vendor = SERIO_HAMPSHIRE;
128 	input_dev->id.product = 0;
129 	input_dev->id.version = 0x0001;
130 	input_dev->dev.parent = &serio->dev;
131 	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
132 	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
133 	input_set_abs_params(phampshire->dev, ABS_X,
134 			     HAMPSHIRE_MIN_XC, HAMPSHIRE_MAX_XC, 0, 0);
135 	input_set_abs_params(phampshire->dev, ABS_Y,
136 			     HAMPSHIRE_MIN_YC, HAMPSHIRE_MAX_YC, 0, 0);
137 
138 	serio_set_drvdata(serio, phampshire);
139 
140 	err = serio_open(serio, drv);
141 	if (err)
142 		goto fail2;
143 
144 	err = input_register_device(phampshire->dev);
145 	if (err)
146 		goto fail3;
147 
148 	return 0;
149 
150  fail3:	serio_close(serio);
151  fail2:	serio_set_drvdata(serio, NULL);
152  fail1:	input_free_device(input_dev);
153 	kfree(phampshire);
154 	return err;
155 }
156 
157 /*
158  * The serio driver structure.
159  */
160 
161 static const struct serio_device_id hampshire_serio_ids[] = {
162 	{
163 		.type	= SERIO_RS232,
164 		.proto	= SERIO_HAMPSHIRE,
165 		.id	= SERIO_ANY,
166 		.extra	= SERIO_ANY,
167 	},
168 	{ 0 }
169 };
170 
171 MODULE_DEVICE_TABLE(serio, hampshire_serio_ids);
172 
173 static struct serio_driver hampshire_drv = {
174 	.driver		= {
175 		.name	= "hampshire",
176 	},
177 	.description	= DRIVER_DESC,
178 	.id_table	= hampshire_serio_ids,
179 	.interrupt	= hampshire_interrupt,
180 	.connect	= hampshire_connect,
181 	.disconnect	= hampshire_disconnect,
182 };
183 
184 module_serio_driver(hampshire_drv);
185