1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Touch Screen driver for EETI's I2C connected touch screen panels
4  *   Copyright (c) 2009,2018 Daniel Mack <daniel@zonque.org>
5  *
6  * See EETI's software guide for the protocol specification:
7  *   http://home.eeti.com.tw/documentation.html
8  *
9  * Based on migor_ts.c
10  *   Copyright (c) 2008 Magnus Damm
11  *   Copyright (c) 2007 Ujjwal Pande <ujjwal@kenati.com>
12  */
13 
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/input.h>
17 #include <linux/input/touchscreen.h>
18 #include <linux/interrupt.h>
19 #include <linux/i2c.h>
20 #include <linux/timer.h>
21 #include <linux/gpio/consumer.h>
22 #include <linux/of.h>
23 #include <linux/slab.h>
24 #include <asm/unaligned.h>
25 
26 struct eeti_ts {
27 	struct i2c_client *client;
28 	struct input_dev *input;
29 	struct gpio_desc *attn_gpio;
30 	struct touchscreen_properties props;
31 	struct mutex mutex;
32 	bool running;
33 };
34 
35 #define EETI_TS_BITDEPTH	(11)
36 #define EETI_MAXVAL		((1 << (EETI_TS_BITDEPTH + 1)) - 1)
37 
38 #define REPORT_BIT_PRESSED	BIT(0)
39 #define REPORT_BIT_AD0		BIT(1)
40 #define REPORT_BIT_AD1		BIT(2)
41 #define REPORT_BIT_HAS_PRESSURE	BIT(6)
42 #define REPORT_RES_BITS(v)	(((v) >> 1) + EETI_TS_BITDEPTH)
43 
44 static void eeti_ts_report_event(struct eeti_ts *eeti, u8 *buf)
45 {
46 	unsigned int res;
47 	u16 x, y;
48 
49 	res = REPORT_RES_BITS(buf[0] & (REPORT_BIT_AD0 | REPORT_BIT_AD1));
50 
51 	x = get_unaligned_be16(&buf[1]);
52 	y = get_unaligned_be16(&buf[3]);
53 
54 	/* fix the range to 11 bits */
55 	x >>= res - EETI_TS_BITDEPTH;
56 	y >>= res - EETI_TS_BITDEPTH;
57 
58 	if (buf[0] & REPORT_BIT_HAS_PRESSURE)
59 		input_report_abs(eeti->input, ABS_PRESSURE, buf[5]);
60 
61 	touchscreen_report_pos(eeti->input, &eeti->props, x, y, false);
62 	input_report_key(eeti->input, BTN_TOUCH, buf[0] & REPORT_BIT_PRESSED);
63 	input_sync(eeti->input);
64 }
65 
66 static int eeti_ts_read(struct eeti_ts *eeti)
67 {
68 	int len, error;
69 	char buf[6];
70 
71 	len = i2c_master_recv(eeti->client, buf, sizeof(buf));
72 	if (len != sizeof(buf)) {
73 		error = len < 0 ? len : -EIO;
74 		dev_err(&eeti->client->dev,
75 			"failed to read touchscreen data: %d\n",
76 			error);
77 		return error;
78 	}
79 
80 	/* Motion packet */
81 	if (buf[0] & 0x80)
82 		eeti_ts_report_event(eeti, buf);
83 
84 	return 0;
85 }
86 
87 static irqreturn_t eeti_ts_isr(int irq, void *dev_id)
88 {
89 	struct eeti_ts *eeti = dev_id;
90 	int error;
91 
92 	mutex_lock(&eeti->mutex);
93 
94 	do {
95 		/*
96 		 * If we have attention GPIO, trust it. Otherwise we'll read
97 		 * once and exit. We assume that in this case we are using
98 		 * level triggered interrupt and it will get raised again
99 		 * if/when there is more data.
100 		 */
101 		if (eeti->attn_gpio &&
102 		    !gpiod_get_value_cansleep(eeti->attn_gpio)) {
103 			break;
104 		}
105 
106 		error = eeti_ts_read(eeti);
107 		if (error)
108 			break;
109 
110 	} while (eeti->running && eeti->attn_gpio);
111 
112 	mutex_unlock(&eeti->mutex);
113 	return IRQ_HANDLED;
114 }
115 
116 static void eeti_ts_start(struct eeti_ts *eeti)
117 {
118 	mutex_lock(&eeti->mutex);
119 
120 	eeti->running = true;
121 	enable_irq(eeti->client->irq);
122 
123 	/*
124 	 * Kick the controller in case we are using edge interrupt and
125 	 * we missed our edge while interrupt was disabled. We expect
126 	 * the attention GPIO to be wired in this case.
127 	 */
128 	if (eeti->attn_gpio && gpiod_get_value_cansleep(eeti->attn_gpio))
129 		eeti_ts_read(eeti);
130 
131 	mutex_unlock(&eeti->mutex);
132 }
133 
134 static void eeti_ts_stop(struct eeti_ts *eeti)
135 {
136 	/*
137 	 * Not locking here, just setting a flag and expect that the
138 	 * interrupt thread will notice the flag eventually.
139 	 */
140 	eeti->running = false;
141 	wmb();
142 	disable_irq(eeti->client->irq);
143 }
144 
145 static int eeti_ts_open(struct input_dev *dev)
146 {
147 	struct eeti_ts *eeti = input_get_drvdata(dev);
148 
149 	eeti_ts_start(eeti);
150 
151 	return 0;
152 }
153 
154 static void eeti_ts_close(struct input_dev *dev)
155 {
156 	struct eeti_ts *eeti = input_get_drvdata(dev);
157 
158 	eeti_ts_stop(eeti);
159 }
160 
161 static int eeti_ts_probe(struct i2c_client *client,
162 			 const struct i2c_device_id *idp)
163 {
164 	struct device *dev = &client->dev;
165 	struct eeti_ts *eeti;
166 	struct input_dev *input;
167 	int error;
168 
169 	/*
170 	 * In contrast to what's described in the datasheet, there seems
171 	 * to be no way of probing the presence of that device using I2C
172 	 * commands. So we need to blindly believe it is there, and wait
173 	 * for interrupts to occur.
174 	 */
175 
176 	eeti = devm_kzalloc(dev, sizeof(*eeti), GFP_KERNEL);
177 	if (!eeti) {
178 		dev_err(dev, "failed to allocate driver data\n");
179 		return -ENOMEM;
180 	}
181 
182 	mutex_init(&eeti->mutex);
183 
184 	input = devm_input_allocate_device(dev);
185 	if (!input) {
186 		dev_err(dev, "Failed to allocate input device.\n");
187 		return -ENOMEM;
188 	}
189 
190 	input_set_capability(input, EV_KEY, BTN_TOUCH);
191 
192 	input_set_abs_params(input, ABS_X, 0, EETI_MAXVAL, 0, 0);
193 	input_set_abs_params(input, ABS_Y, 0, EETI_MAXVAL, 0, 0);
194 	input_set_abs_params(input, ABS_PRESSURE, 0, 0xff, 0, 0);
195 
196 	touchscreen_parse_properties(input, false, &eeti->props);
197 
198 	input->name = client->name;
199 	input->id.bustype = BUS_I2C;
200 	input->open = eeti_ts_open;
201 	input->close = eeti_ts_close;
202 
203 	eeti->client = client;
204 	eeti->input = input;
205 
206 	eeti->attn_gpio = devm_gpiod_get_optional(dev, "attn", GPIOD_IN);
207 	if (IS_ERR(eeti->attn_gpio))
208 		return PTR_ERR(eeti->attn_gpio);
209 
210 	i2c_set_clientdata(client, eeti);
211 	input_set_drvdata(input, eeti);
212 
213 	error = devm_request_threaded_irq(dev, client->irq,
214 					  NULL, eeti_ts_isr,
215 					  IRQF_ONESHOT,
216 					  client->name, eeti);
217 	if (error) {
218 		dev_err(dev, "Unable to request touchscreen IRQ: %d\n",
219 			error);
220 		return error;
221 	}
222 
223 	/*
224 	 * Disable the device for now. It will be enabled once the
225 	 * input device is opened.
226 	 */
227 	eeti_ts_stop(eeti);
228 
229 	error = input_register_device(input);
230 	if (error)
231 		return error;
232 
233 	return 0;
234 }
235 
236 static int __maybe_unused eeti_ts_suspend(struct device *dev)
237 {
238 	struct i2c_client *client = to_i2c_client(dev);
239 	struct eeti_ts *eeti = i2c_get_clientdata(client);
240 	struct input_dev *input_dev = eeti->input;
241 
242 	mutex_lock(&input_dev->mutex);
243 
244 	if (input_device_enabled(input_dev))
245 		eeti_ts_stop(eeti);
246 
247 	mutex_unlock(&input_dev->mutex);
248 
249 	if (device_may_wakeup(&client->dev))
250 		enable_irq_wake(client->irq);
251 
252 	return 0;
253 }
254 
255 static int __maybe_unused eeti_ts_resume(struct device *dev)
256 {
257 	struct i2c_client *client = to_i2c_client(dev);
258 	struct eeti_ts *eeti = i2c_get_clientdata(client);
259 	struct input_dev *input_dev = eeti->input;
260 
261 	if (device_may_wakeup(&client->dev))
262 		disable_irq_wake(client->irq);
263 
264 	mutex_lock(&input_dev->mutex);
265 
266 	if (input_device_enabled(input_dev))
267 		eeti_ts_start(eeti);
268 
269 	mutex_unlock(&input_dev->mutex);
270 
271 	return 0;
272 }
273 
274 static SIMPLE_DEV_PM_OPS(eeti_ts_pm, eeti_ts_suspend, eeti_ts_resume);
275 
276 static const struct i2c_device_id eeti_ts_id[] = {
277 	{ "eeti_ts", 0 },
278 	{ }
279 };
280 MODULE_DEVICE_TABLE(i2c, eeti_ts_id);
281 
282 #ifdef CONFIG_OF
283 static const struct of_device_id of_eeti_ts_match[] = {
284 	{ .compatible = "eeti,exc3000-i2c", },
285 	{ }
286 };
287 #endif
288 
289 static struct i2c_driver eeti_ts_driver = {
290 	.driver = {
291 		.name = "eeti_ts",
292 		.pm = &eeti_ts_pm,
293 		.of_match_table = of_match_ptr(of_eeti_ts_match),
294 	},
295 	.probe = eeti_ts_probe,
296 	.id_table = eeti_ts_id,
297 };
298 
299 module_i2c_driver(eeti_ts_driver);
300 
301 MODULE_DESCRIPTION("EETI Touchscreen driver");
302 MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
303 MODULE_LICENSE("GPL");
304