1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Sahara TouchIT-213 serial touchscreen driver
4  *
5  * Copyright (c) 2007-2008 Claudio Nieder <private@claudio.ch>
6  *
7  * Based on Touchright driver (drivers/input/touchscreen/touchright.c)
8  * Copyright (c) 2006 Rick Koch <n1gp@hotmail.com>
9  * Copyright (c) 2004 Vojtech Pavlik
10  * and Dan Streetman <ddstreet@ieee.org>
11  */
12 
13 
14 #include <linux/errno.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/input.h>
19 #include <linux/serio.h>
20 
21 #define DRIVER_DESC	"Sahara TouchIT-213 serial touchscreen driver"
22 
23 MODULE_AUTHOR("Claudio Nieder <private@claudio.ch>");
24 MODULE_DESCRIPTION(DRIVER_DESC);
25 MODULE_LICENSE("GPL");
26 
27 /*
28  * Definitions & global arrays.
29  */
30 
31 /*
32  * Data is received through COM1 at 9600bit/s,8bit,no parity in packets
33  * of 5 byte each.
34  *
35  *   +--------+   +--------+   +--------+   +--------+   +--------+
36  *   |1000000p|   |0xxxxxxx|   |0xxxxxxx|   |0yyyyyyy|   |0yyyyyyy|
37  *   +--------+   +--------+   +--------+   +--------+   +--------+
38  *                    MSB          LSB          MSB          LSB
39  *
40  * The value of p is 1 as long as the screen is touched and 0 when
41  * reporting the location where touching stopped, e.g. where the pen was
42  * lifted from the screen.
43  *
44  * When holding the screen in landscape mode as the BIOS text output is
45  * presented, x is the horizontal axis with values growing from left to
46  * right and y is the vertical axis with values growing from top to
47  * bottom.
48  *
49  * When holding the screen in portrait mode with the Sahara logo in its
50  * correct position, x ist the vertical axis with values growing from
51  * top to bottom and y is the horizontal axis with values growing from
52  * right to left.
53  */
54 
55 #define T213_FORMAT_TOUCH_BIT	0x01
56 #define T213_FORMAT_STATUS_BYTE	0x80
57 #define T213_FORMAT_STATUS_MASK	~T213_FORMAT_TOUCH_BIT
58 
59 /*
60  * On my Sahara Touch-IT 213 I have observed x values from 0 to 0x7f0
61  * and y values from 0x1d to 0x7e9, so the actual measurement is
62  * probably done with an 11 bit precision.
63  */
64 #define T213_MIN_XC 0
65 #define T213_MAX_XC 0x07ff
66 #define T213_MIN_YC 0
67 #define T213_MAX_YC 0x07ff
68 
69 /*
70  * Per-touchscreen data.
71  */
72 
73 struct touchit213 {
74 	struct input_dev *dev;
75 	struct serio *serio;
76 	int idx;
77 	unsigned char csum;
78 	unsigned char data[5];
79 	char phys[32];
80 };
81 
touchit213_interrupt(struct serio * serio,unsigned char data,unsigned int flags)82 static irqreturn_t touchit213_interrupt(struct serio *serio,
83 		unsigned char data, unsigned int flags)
84 {
85 	struct touchit213 *touchit213 = serio_get_drvdata(serio);
86 	struct input_dev *dev = touchit213->dev;
87 
88 	touchit213->data[touchit213->idx] = data;
89 
90 	switch (touchit213->idx++) {
91 	case 0:
92 		if ((touchit213->data[0] & T213_FORMAT_STATUS_MASK) !=
93 				T213_FORMAT_STATUS_BYTE) {
94 			pr_debug("unsynchronized data: 0x%02x\n", data);
95 			touchit213->idx = 0;
96 		}
97 		break;
98 
99 	case 4:
100 		touchit213->idx = 0;
101 		input_report_abs(dev, ABS_X,
102 			(touchit213->data[1] << 7) | touchit213->data[2]);
103 		input_report_abs(dev, ABS_Y,
104 			(touchit213->data[3] << 7) | touchit213->data[4]);
105 		input_report_key(dev, BTN_TOUCH,
106 			touchit213->data[0] & T213_FORMAT_TOUCH_BIT);
107 		input_sync(dev);
108 		break;
109 	}
110 
111 	return IRQ_HANDLED;
112 }
113 
114 /*
115  * touchit213_disconnect() is the opposite of touchit213_connect()
116  */
117 
touchit213_disconnect(struct serio * serio)118 static void touchit213_disconnect(struct serio *serio)
119 {
120 	struct touchit213 *touchit213 = serio_get_drvdata(serio);
121 
122 	input_get_device(touchit213->dev);
123 	input_unregister_device(touchit213->dev);
124 	serio_close(serio);
125 	serio_set_drvdata(serio, NULL);
126 	input_put_device(touchit213->dev);
127 	kfree(touchit213);
128 }
129 
130 /*
131  * touchit213_connect() is the routine that is called when someone adds a
132  * new serio device that supports the Touchright protocol and registers it as
133  * an input device.
134  */
135 
touchit213_connect(struct serio * serio,struct serio_driver * drv)136 static int touchit213_connect(struct serio *serio, struct serio_driver *drv)
137 {
138 	struct touchit213 *touchit213;
139 	struct input_dev *input_dev;
140 	int err;
141 
142 	touchit213 = kzalloc(sizeof(struct touchit213), GFP_KERNEL);
143 	input_dev = input_allocate_device();
144 	if (!touchit213 || !input_dev) {
145 		err = -ENOMEM;
146 		goto fail1;
147 	}
148 
149 	touchit213->serio = serio;
150 	touchit213->dev = input_dev;
151 	snprintf(touchit213->phys, sizeof(touchit213->phys),
152 		 "%s/input0", serio->phys);
153 
154 	input_dev->name = "Sahara Touch-iT213 Serial TouchScreen";
155 	input_dev->phys = touchit213->phys;
156 	input_dev->id.bustype = BUS_RS232;
157 	input_dev->id.vendor = SERIO_TOUCHIT213;
158 	input_dev->id.product = 0;
159 	input_dev->id.version = 0x0100;
160 	input_dev->dev.parent = &serio->dev;
161 	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
162 	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
163 	input_set_abs_params(touchit213->dev, ABS_X,
164 			     T213_MIN_XC, T213_MAX_XC, 0, 0);
165 	input_set_abs_params(touchit213->dev, ABS_Y,
166 			     T213_MIN_YC, T213_MAX_YC, 0, 0);
167 
168 	serio_set_drvdata(serio, touchit213);
169 
170 	err = serio_open(serio, drv);
171 	if (err)
172 		goto fail2;
173 
174 	err = input_register_device(touchit213->dev);
175 	if (err)
176 		goto fail3;
177 
178 	return 0;
179 
180  fail3:	serio_close(serio);
181  fail2:	serio_set_drvdata(serio, NULL);
182  fail1:	input_free_device(input_dev);
183 	kfree(touchit213);
184 	return err;
185 }
186 
187 /*
188  * The serio driver structure.
189  */
190 
191 static const struct serio_device_id touchit213_serio_ids[] = {
192 	{
193 		.type	= SERIO_RS232,
194 		.proto	= SERIO_TOUCHIT213,
195 		.id	= SERIO_ANY,
196 		.extra	= SERIO_ANY,
197 	},
198 	{ 0 }
199 };
200 
201 MODULE_DEVICE_TABLE(serio, touchit213_serio_ids);
202 
203 static struct serio_driver touchit213_drv = {
204 	.driver		= {
205 		.name	= "touchit213",
206 	},
207 	.description	= DRIVER_DESC,
208 	.id_table	= touchit213_serio_ids,
209 	.interrupt	= touchit213_interrupt,
210 	.connect	= touchit213_connect,
211 	.disconnect	= touchit213_disconnect,
212 };
213 
214 module_serio_driver(touchit213_drv);
215