1 /*
2  * Touch Screen driver for SiS 9200 family I2C Touch panels
3  *
4  * Copyright (C) 2015 SiS, Inc.
5  * Copyright (C) 2016 Nextfour Group
6  *
7  * This software is licensed under the terms of the GNU General Public
8  * License version 2, as published by the Free Software Foundation, and
9  * may be copied, distributed, and modified under those terms.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  */
16 
17 #include <linux/crc-itu-t.h>
18 #include <linux/delay.h>
19 #include <linux/i2c.h>
20 #include <linux/input.h>
21 #include <linux/input/mt.h>
22 #include <linux/interrupt.h>
23 #include <linux/gpio/consumer.h>
24 #include <linux/module.h>
25 #include <linux/slab.h>
26 #include <asm/unaligned.h>
27 
28 #define SIS_I2C_NAME		"sis_i2c_ts"
29 
30 /*
31  * The I2C packet format:
32  * le16		byte count
33  * u8		Report ID
34  * <contact data - variable length>
35  * u8		Number of contacts
36  * le16		Scan Time (optional)
37  * le16		CRC
38  *
39  * One touch point information consists of 6+ bytes, the order is:
40  * u8		contact state
41  * u8		finger id
42  * le16		x axis
43  * le16		y axis
44  * u8		contact width (optional)
45  * u8		contact height (optional)
46  * u8		pressure (optional)
47  *
48  * Maximum amount of data transmitted in one shot is 64 bytes, if controller
49  * needs to report more contacts than fit in one packet it will send true
50  * number of contacts in first packet and 0 as number of contacts in second
51  * packet.
52  */
53 
54 #define SIS_MAX_PACKET_SIZE		64
55 
56 #define SIS_PKT_LEN_OFFSET		0
57 #define SIS_PKT_REPORT_OFFSET		2 /* Report ID/type */
58 #define SIS_PKT_CONTACT_OFFSET		3 /* First contact */
59 
60 #define SIS_SCAN_TIME_LEN		2
61 
62 /* Supported report types */
63 #define SIS_ALL_IN_ONE_PACKAGE		0x10
64 #define SIS_PKT_IS_TOUCH(x)		(((x) & 0x0f) == 0x01)
65 #define SIS_PKT_IS_HIDI2C(x)		(((x) & 0x0f) == 0x06)
66 
67 /* Contact properties within report */
68 #define SIS_PKT_HAS_AREA(x)		((x) & BIT(4))
69 #define SIS_PKT_HAS_PRESSURE(x)		((x) & BIT(5))
70 #define SIS_PKT_HAS_SCANTIME(x)		((x) & BIT(6))
71 
72 /* Contact size */
73 #define SIS_BASE_LEN_PER_CONTACT	6
74 #define SIS_AREA_LEN_PER_CONTACT	2
75 #define SIS_PRESSURE_LEN_PER_CONTACT	1
76 
77 /* Offsets within contact data */
78 #define SIS_CONTACT_STATUS_OFFSET	0
79 #define SIS_CONTACT_ID_OFFSET		1 /* Contact ID */
80 #define SIS_CONTACT_X_OFFSET		2
81 #define SIS_CONTACT_Y_OFFSET		4
82 #define SIS_CONTACT_WIDTH_OFFSET	6
83 #define SIS_CONTACT_HEIGHT_OFFSET	7
84 #define SIS_CONTACT_PRESSURE_OFFSET(id)	(SIS_PKT_HAS_AREA(id) ? 8 : 6)
85 
86 /* Individual contact state */
87 #define SIS_STATUS_UP			0x0
88 #define SIS_STATUS_DOWN			0x3
89 
90 /* Touchscreen parameters */
91 #define SIS_MAX_FINGERS			10
92 #define SIS_MAX_X			4095
93 #define SIS_MAX_Y			4095
94 #define SIS_MAX_PRESSURE		255
95 
96 /* Resolution diagonal */
97 #define SIS_AREA_LENGTH_LONGER		5792
98 /*((SIS_MAX_X^2) + (SIS_MAX_Y^2))^0.5*/
99 #define SIS_AREA_LENGTH_SHORT		5792
100 #define SIS_AREA_UNIT			(5792 / 32)
101 
102 struct sis_ts_data {
103 	struct i2c_client *client;
104 	struct input_dev *input;
105 
106 	struct gpio_desc *attn_gpio;
107 	struct gpio_desc *reset_gpio;
108 
109 	u8 packet[SIS_MAX_PACKET_SIZE];
110 };
111 
112 static int sis_read_packet(struct i2c_client *client, u8 *buf,
113 			   unsigned int *num_contacts,
114 			   unsigned int *contact_size)
115 {
116 	int count_idx;
117 	int ret;
118 	u16 len;
119 	u16 crc, pkg_crc;
120 	u8 report_id;
121 
122 	ret = i2c_master_recv(client, buf, SIS_MAX_PACKET_SIZE);
123 	if (ret <= 0)
124 		return -EIO;
125 
126 	len = get_unaligned_le16(&buf[SIS_PKT_LEN_OFFSET]);
127 	if (len > SIS_MAX_PACKET_SIZE) {
128 		dev_err(&client->dev,
129 			"%s: invalid packet length (%d vs %d)\n",
130 			__func__, len, SIS_MAX_PACKET_SIZE);
131 		return -E2BIG;
132 	}
133 
134 	if (len < 10)
135 		return -EINVAL;
136 
137 	report_id = buf[SIS_PKT_REPORT_OFFSET];
138 	count_idx  = len - 1;
139 	*contact_size = SIS_BASE_LEN_PER_CONTACT;
140 
141 	if (report_id != SIS_ALL_IN_ONE_PACKAGE) {
142 		if (SIS_PKT_IS_TOUCH(report_id)) {
143 			/*
144 			 * Calculate CRC ignoring packet length
145 			 * in the beginning and CRC transmitted
146 			 * at the end of the packet.
147 			 */
148 			crc = crc_itu_t(0, buf + 2, len - 2 - 2);
149 			pkg_crc = get_unaligned_le16(&buf[len - 2]);
150 
151 			if (crc != pkg_crc) {
152 				dev_err(&client->dev,
153 					"%s: CRC Error (%d vs %d)\n",
154 					__func__, crc, pkg_crc);
155 				return -EINVAL;
156 			}
157 
158 			count_idx -= 2;
159 
160 		} else if (!SIS_PKT_IS_HIDI2C(report_id)) {
161 			dev_err(&client->dev,
162 				"%s: invalid packet ID %#02x\n",
163 				__func__, report_id);
164 			return -EINVAL;
165 		}
166 
167 		if (SIS_PKT_HAS_SCANTIME(report_id))
168 			count_idx -= SIS_SCAN_TIME_LEN;
169 
170 		if (SIS_PKT_HAS_AREA(report_id))
171 			*contact_size += SIS_AREA_LEN_PER_CONTACT;
172 		if (SIS_PKT_HAS_PRESSURE(report_id))
173 			*contact_size += SIS_PRESSURE_LEN_PER_CONTACT;
174 	}
175 
176 	*num_contacts = buf[count_idx];
177 	return 0;
178 }
179 
180 static int sis_ts_report_contact(struct sis_ts_data *ts, const u8 *data, u8 id)
181 {
182 	struct input_dev *input = ts->input;
183 	int slot;
184 	u8 status = data[SIS_CONTACT_STATUS_OFFSET];
185 	u8 pressure;
186 	u8 height, width;
187 	u16 x, y;
188 
189 	if (status != SIS_STATUS_DOWN && status != SIS_STATUS_UP) {
190 		dev_err(&ts->client->dev, "Unexpected touch status: %#02x\n",
191 			data[SIS_CONTACT_STATUS_OFFSET]);
192 		return -EINVAL;
193 	}
194 
195 	slot = input_mt_get_slot_by_key(input, data[SIS_CONTACT_ID_OFFSET]);
196 	if (slot < 0)
197 		return -ENOENT;
198 
199 	input_mt_slot(input, slot);
200 	input_mt_report_slot_state(input, MT_TOOL_FINGER,
201 				   status == SIS_STATUS_DOWN);
202 
203 	if (status == SIS_STATUS_DOWN) {
204 		pressure = height = width = 1;
205 		if (id != SIS_ALL_IN_ONE_PACKAGE) {
206 			if (SIS_PKT_HAS_AREA(id)) {
207 				width = data[SIS_CONTACT_WIDTH_OFFSET];
208 				height = data[SIS_CONTACT_HEIGHT_OFFSET];
209 			}
210 
211 			if (SIS_PKT_HAS_PRESSURE(id))
212 				pressure =
213 					data[SIS_CONTACT_PRESSURE_OFFSET(id)];
214 		}
215 
216 		x = get_unaligned_le16(&data[SIS_CONTACT_X_OFFSET]);
217 		y = get_unaligned_le16(&data[SIS_CONTACT_Y_OFFSET]);
218 
219 		input_report_abs(input, ABS_MT_TOUCH_MAJOR,
220 				 width * SIS_AREA_UNIT);
221 		input_report_abs(input, ABS_MT_TOUCH_MINOR,
222 				 height * SIS_AREA_UNIT);
223 		input_report_abs(input, ABS_MT_PRESSURE, pressure);
224 		input_report_abs(input, ABS_MT_POSITION_X, x);
225 		input_report_abs(input, ABS_MT_POSITION_Y, y);
226 	}
227 
228 	return 0;
229 }
230 
231 static void sis_ts_handle_packet(struct sis_ts_data *ts)
232 {
233 	const u8 *contact;
234 	unsigned int num_to_report = 0;
235 	unsigned int num_contacts;
236 	unsigned int num_reported;
237 	unsigned int contact_size;
238 	int error;
239 	u8 report_id;
240 
241 	do {
242 		error = sis_read_packet(ts->client, ts->packet,
243 					&num_contacts, &contact_size);
244 		if (error)
245 			break;
246 
247 		if (num_to_report == 0) {
248 			num_to_report = num_contacts;
249 		} else if (num_contacts != 0) {
250 			dev_err(&ts->client->dev,
251 				"%s: nonzero (%d) point count in tail packet\n",
252 				__func__, num_contacts);
253 			break;
254 		}
255 
256 		report_id = ts->packet[SIS_PKT_REPORT_OFFSET];
257 		contact = &ts->packet[SIS_PKT_CONTACT_OFFSET];
258 		num_reported = 0;
259 
260 		while (num_to_report > 0) {
261 			error = sis_ts_report_contact(ts, contact, report_id);
262 			if (error)
263 				break;
264 
265 			contact += contact_size;
266 			num_to_report--;
267 			num_reported++;
268 
269 			if (report_id != SIS_ALL_IN_ONE_PACKAGE &&
270 			    num_reported >= 5) {
271 				/*
272 				 * The remainder of contacts is sent
273 				 * in the 2nd packet.
274 				 */
275 				break;
276 			}
277 		}
278 	} while (num_to_report > 0);
279 
280 	input_mt_sync_frame(ts->input);
281 	input_sync(ts->input);
282 }
283 
284 static irqreturn_t sis_ts_irq_handler(int irq, void *dev_id)
285 {
286 	struct sis_ts_data *ts = dev_id;
287 
288 	do {
289 		sis_ts_handle_packet(ts);
290 	} while (ts->attn_gpio && gpiod_get_value_cansleep(ts->attn_gpio));
291 
292 	return IRQ_HANDLED;
293 }
294 
295 static void sis_ts_reset(struct sis_ts_data *ts)
296 {
297 	if (ts->reset_gpio) {
298 		/* Get out of reset */
299 		usleep_range(1000, 2000);
300 		gpiod_set_value(ts->reset_gpio, 1);
301 		usleep_range(1000, 2000);
302 		gpiod_set_value(ts->reset_gpio, 0);
303 		msleep(100);
304 	}
305 }
306 
307 static int sis_ts_probe(struct i2c_client *client,
308 			const struct i2c_device_id *id)
309 {
310 	struct sis_ts_data *ts;
311 	struct input_dev *input;
312 	int error;
313 
314 	ts = devm_kzalloc(&client->dev, sizeof(*ts), GFP_KERNEL);
315 	if (!ts)
316 		return -ENOMEM;
317 
318 	ts->client = client;
319 	i2c_set_clientdata(client, ts);
320 
321 	ts->attn_gpio = devm_gpiod_get_optional(&client->dev,
322 						"attn", GPIOD_IN);
323 	if (IS_ERR(ts->attn_gpio)) {
324 		error = PTR_ERR(ts->attn_gpio);
325 		if (error != -EPROBE_DEFER)
326 			dev_err(&client->dev,
327 				"Failed to get attention GPIO: %d\n", error);
328 		return error;
329 	}
330 
331 	ts->reset_gpio = devm_gpiod_get_optional(&client->dev,
332 						 "reset", GPIOD_OUT_LOW);
333 	if (IS_ERR(ts->reset_gpio)) {
334 		error = PTR_ERR(ts->reset_gpio);
335 		if (error != -EPROBE_DEFER)
336 			dev_err(&client->dev,
337 				"Failed to get reset GPIO: %d\n", error);
338 		return error;
339 	}
340 
341 	sis_ts_reset(ts);
342 
343 	ts->input = input = devm_input_allocate_device(&client->dev);
344 	if (!input) {
345 		dev_err(&client->dev, "Failed to allocate input device\n");
346 		return -ENOMEM;
347 	}
348 
349 	input->name = "SiS Touchscreen";
350 	input->id.bustype = BUS_I2C;
351 
352 	input_set_abs_params(input, ABS_MT_POSITION_X, 0, SIS_MAX_X, 0, 0);
353 	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, SIS_MAX_Y, 0, 0);
354 	input_set_abs_params(input, ABS_MT_PRESSURE, 0, SIS_MAX_PRESSURE, 0, 0);
355 	input_set_abs_params(input, ABS_MT_TOUCH_MAJOR,
356 			     0, SIS_AREA_LENGTH_LONGER, 0, 0);
357 	input_set_abs_params(input, ABS_MT_TOUCH_MINOR,
358 			     0, SIS_AREA_LENGTH_SHORT, 0, 0);
359 
360 	error = input_mt_init_slots(input, SIS_MAX_FINGERS, INPUT_MT_DIRECT);
361 	if (error) {
362 		dev_err(&client->dev,
363 			"Failed to initialize MT slots: %d\n", error);
364 		return error;
365 	}
366 
367 	error = devm_request_threaded_irq(&client->dev, client->irq,
368 					  NULL, sis_ts_irq_handler,
369 					  IRQF_ONESHOT,
370 					  client->name, ts);
371 	if (error) {
372 		dev_err(&client->dev, "Failed to request IRQ: %d\n", error);
373 		return error;
374 	}
375 
376 	error = input_register_device(ts->input);
377 	if (error) {
378 		dev_err(&client->dev,
379 			"Failed to register input device: %d\n", error);
380 		return error;
381 	}
382 
383 	return 0;
384 }
385 
386 #ifdef CONFIG_OF
387 static const struct of_device_id sis_ts_dt_ids[] = {
388 	{ .compatible = "sis,9200-ts" },
389 	{ /* sentinel */ }
390 };
391 MODULE_DEVICE_TABLE(of, sis_ts_dt_ids);
392 #endif
393 
394 static const struct i2c_device_id sis_ts_id[] = {
395 	{ SIS_I2C_NAME,	0 },
396 	{ "9200-ts",	0 },
397 	{ /* sentinel */  }
398 };
399 MODULE_DEVICE_TABLE(i2c, sis_ts_id);
400 
401 static struct i2c_driver sis_ts_driver = {
402 	.driver = {
403 		.name	= SIS_I2C_NAME,
404 		.of_match_table = of_match_ptr(sis_ts_dt_ids),
405 	},
406 	.probe		= sis_ts_probe,
407 	.id_table	= sis_ts_id,
408 };
409 module_i2c_driver(sis_ts_driver);
410 
411 MODULE_DESCRIPTION("SiS 9200 Family Touchscreen Driver");
412 MODULE_LICENSE("GPL v2");
413 MODULE_AUTHOR("Mika Penttilä <mika.penttila@nextfour.com>");
414