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touchit213.c
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1 /*
2  * Sahara TouchIT-213 serial touchscreen driver
3  *
4  * Copyright (c) 2007-2008 Claudio Nieder <[email protected]>
5  *
6  * Based on Touchright driver (drivers/input/touchscreen/touchright.c)
7  * Copyright (c) 2006 Rick Koch <[email protected]>
8  * Copyright (c) 2004 Vojtech Pavlik
9  * and Dan Streetman <[email protected]>
10  */
11 
12 /*
13  * This program is free software; you can redistribute it and/or modify it
14  * under the terms of the GNU General Public License version 2 as published
15  * by the Free Software Foundation.
16  */
17 
18 #include <linux/errno.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/slab.h>
22 #include <linux/input.h>
23 #include <linux/serio.h>
24 #include <linux/init.h>
25 
26 #define DRIVER_DESC "Sahara TouchIT-213 serial touchscreen driver"
27 
28 MODULE_AUTHOR("Claudio Nieder <[email protected]>");
30 MODULE_LICENSE("GPL");
31 
32 /*
33  * Definitions & global arrays.
34  */
35 
36 /*
37  * Data is received through COM1 at 9600bit/s,8bit,no parity in packets
38  * of 5 byte each.
39  *
40  * +--------+ +--------+ +--------+ +--------+ +--------+
41  * |1000000p| |0xxxxxxx| |0xxxxxxx| |0yyyyyyy| |0yyyyyyy|
42  * +--------+ +--------+ +--------+ +--------+ +--------+
43  * MSB LSB MSB LSB
44  *
45  * The value of p is 1 as long as the screen is touched and 0 when
46  * reporting the location where touching stopped, e.g. where the pen was
47  * lifted from the screen.
48  *
49  * When holding the screen in landscape mode as the BIOS text output is
50  * presented, x is the horizontal axis with values growing from left to
51  * right and y is the vertical axis with values growing from top to
52  * bottom.
53  *
54  * When holding the screen in portrait mode with the Sahara logo in its
55  * correct position, x ist the vertical axis with values growing from
56  * top to bottom and y is the horizontal axis with values growing from
57  * right to left.
58  */
59 
60 #define T213_FORMAT_TOUCH_BIT 0x01
61 #define T213_FORMAT_STATUS_BYTE 0x80
62 #define T213_FORMAT_STATUS_MASK ~T213_FORMAT_TOUCH_BIT
63 
64 /*
65  * On my Sahara Touch-IT 213 I have observed x values from 0 to 0x7f0
66  * and y values from 0x1d to 0x7e9, so the actual measurement is
67  * probably done with an 11 bit precision.
68  */
69 #define T213_MIN_XC 0
70 #define T213_MAX_XC 0x07ff
71 #define T213_MIN_YC 0
72 #define T213_MAX_YC 0x07ff
73 
74 /*
75  * Per-touchscreen data.
76  */
77 
78 struct touchit213 {
79  struct input_dev *dev;
80  struct serio *serio;
81  int idx;
82  unsigned char csum;
83  unsigned char data[5];
84  char phys[32];
85 };
86 
87 static irqreturn_t touchit213_interrupt(struct serio *serio,
88  unsigned char data, unsigned int flags)
89 {
90  struct touchit213 *touchit213 = serio_get_drvdata(serio);
91  struct input_dev *dev = touchit213->dev;
92 
93  touchit213->data[touchit213->idx] = data;
94 
95  switch (touchit213->idx++) {
96  case 0:
97  if ((touchit213->data[0] & T213_FORMAT_STATUS_MASK) !=
99  pr_debug("unsynchronized data: 0x%02x\n", data);
100  touchit213->idx = 0;
101  }
102  break;
103 
104  case 4:
105  touchit213->idx = 0;
106  input_report_abs(dev, ABS_X,
107  (touchit213->data[1] << 7) | touchit213->data[2]);
108  input_report_abs(dev, ABS_Y,
109  (touchit213->data[3] << 7) | touchit213->data[4]);
110  input_report_key(dev, BTN_TOUCH,
111  touchit213->data[0] & T213_FORMAT_TOUCH_BIT);
112  input_sync(dev);
113  break;
114  }
115 
116  return IRQ_HANDLED;
117 }
118 
119 /*
120  * touchit213_disconnect() is the opposite of touchit213_connect()
121  */
122 
123 static void touchit213_disconnect(struct serio *serio)
124 {
125  struct touchit213 *touchit213 = serio_get_drvdata(serio);
126 
127  input_get_device(touchit213->dev);
128  input_unregister_device(touchit213->dev);
129  serio_close(serio);
130  serio_set_drvdata(serio, NULL);
131  input_put_device(touchit213->dev);
132  kfree(touchit213);
133 }
134 
135 /*
136  * touchit213_connect() is the routine that is called when someone adds a
137  * new serio device that supports the Touchright protocol and registers it as
138  * an input device.
139  */
140 
141 static int touchit213_connect(struct serio *serio, struct serio_driver *drv)
142 {
143  struct touchit213 *touchit213;
144  struct input_dev *input_dev;
145  int err;
146 
147  touchit213 = kzalloc(sizeof(struct touchit213), GFP_KERNEL);
148  input_dev = input_allocate_device();
149  if (!touchit213 || !input_dev) {
150  err = -ENOMEM;
151  goto fail1;
152  }
153 
154  touchit213->serio = serio;
155  touchit213->dev = input_dev;
156  snprintf(touchit213->phys, sizeof(touchit213->phys),
157  "%s/input0", serio->phys);
158 
159  input_dev->name = "Sahara Touch-iT213 Serial TouchScreen";
160  input_dev->phys = touchit213->phys;
161  input_dev->id.bustype = BUS_RS232;
162  input_dev->id.vendor = SERIO_TOUCHIT213;
163  input_dev->id.product = 0;
164  input_dev->id.version = 0x0100;
165  input_dev->dev.parent = &serio->dev;
166  input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
167  input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
168  input_set_abs_params(touchit213->dev, ABS_X,
169  T213_MIN_XC, T213_MAX_XC, 0, 0);
170  input_set_abs_params(touchit213->dev, ABS_Y,
171  T213_MIN_YC, T213_MAX_YC, 0, 0);
172 
173  serio_set_drvdata(serio, touchit213);
174 
175  err = serio_open(serio, drv);
176  if (err)
177  goto fail2;
178 
179  err = input_register_device(touchit213->dev);
180  if (err)
181  goto fail3;
182 
183  return 0;
184 
185  fail3: serio_close(serio);
186  fail2: serio_set_drvdata(serio, NULL);
187  fail1: input_free_device(input_dev);
188  kfree(touchit213);
189  return err;
190 }
191 
192 /*
193  * The serio driver structure.
194  */
195 
196 static struct serio_device_id touchit213_serio_ids[] = {
197  {
198  .type = SERIO_RS232,
199  .proto = SERIO_TOUCHIT213,
200  .id = SERIO_ANY,
201  .extra = SERIO_ANY,
202  },
203  { 0 }
204 };
205 
206 MODULE_DEVICE_TABLE(serio, touchit213_serio_ids);
207 
208 static struct serio_driver touchit213_drv = {
209  .driver = {
210  .name = "touchit213",
211  },
212  .description = DRIVER_DESC,
213  .id_table = touchit213_serio_ids,
214  .interrupt = touchit213_interrupt,
215  .connect = touchit213_connect,
216  .disconnect = touchit213_disconnect,
217 };
218 
219 module_serio_driver(touchit213_drv);