1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Touch Screen driver for SiS 9200 family I2C Touch panels
4 *
5 * Copyright (C) 2015 SiS, Inc.
6 * Copyright (C) 2016 Nextfour Group
7 */
8
9#include <linux/crc-itu-t.h>
10#include <linux/delay.h>
11#include <linux/i2c.h>
12#include <linux/input.h>
13#include <linux/input/mt.h>
14#include <linux/interrupt.h>
15#include <linux/gpio/consumer.h>
16#include <linux/module.h>
17#include <linux/slab.h>
18#include <asm/unaligned.h>
19
20#define SIS_I2C_NAME		"sis_i2c_ts"
21
22/*
23 * The I2C packet format:
24 * le16		byte count
25 * u8		Report ID
26 * <contact data - variable length>
27 * u8		Number of contacts
28 * le16		Scan Time (optional)
29 * le16		CRC
30 *
31 * One touch point information consists of 6+ bytes, the order is:
32 * u8		contact state
33 * u8		finger id
34 * le16		x axis
35 * le16		y axis
36 * u8		contact width (optional)
37 * u8		contact height (optional)
38 * u8		pressure (optional)
39 *
40 * Maximum amount of data transmitted in one shot is 64 bytes, if controller
41 * needs to report more contacts than fit in one packet it will send true
42 * number of contacts in first packet and 0 as number of contacts in second
43 * packet.
44 */
45
46#define SIS_MAX_PACKET_SIZE		64
47
48#define SIS_PKT_LEN_OFFSET		0
49#define SIS_PKT_REPORT_OFFSET		2 /* Report ID/type */
50#define SIS_PKT_CONTACT_OFFSET		3 /* First contact */
51
52#define SIS_SCAN_TIME_LEN		2
53
54/* Supported report types */
55#define SIS_ALL_IN_ONE_PACKAGE		0x10
56#define SIS_PKT_IS_TOUCH(x)		(((x) & 0x0f) == 0x01)
57#define SIS_PKT_IS_HIDI2C(x)		(((x) & 0x0f) == 0x06)
58
59/* Contact properties within report */
60#define SIS_PKT_HAS_AREA(x)		((x) & BIT(4))
61#define SIS_PKT_HAS_PRESSURE(x)		((x) & BIT(5))
62#define SIS_PKT_HAS_SCANTIME(x)		((x) & BIT(6))
63
64/* Contact size */
65#define SIS_BASE_LEN_PER_CONTACT	6
66#define SIS_AREA_LEN_PER_CONTACT	2
67#define SIS_PRESSURE_LEN_PER_CONTACT	1
68
69/* Offsets within contact data */
70#define SIS_CONTACT_STATUS_OFFSET	0
71#define SIS_CONTACT_ID_OFFSET		1 /* Contact ID */
72#define SIS_CONTACT_X_OFFSET		2
73#define SIS_CONTACT_Y_OFFSET		4
74#define SIS_CONTACT_WIDTH_OFFSET	6
75#define SIS_CONTACT_HEIGHT_OFFSET	7
76#define SIS_CONTACT_PRESSURE_OFFSET(id)	(SIS_PKT_HAS_AREA(id) ? 8 : 6)
77
78/* Individual contact state */
79#define SIS_STATUS_UP			0x0
80#define SIS_STATUS_DOWN			0x3
81
82/* Touchscreen parameters */
83#define SIS_MAX_FINGERS			10
84#define SIS_MAX_X			4095
85#define SIS_MAX_Y			4095
86#define SIS_MAX_PRESSURE		255
87
88/* Resolution diagonal */
89#define SIS_AREA_LENGTH_LONGER		5792
90/*((SIS_MAX_X^2) + (SIS_MAX_Y^2))^0.5*/
91#define SIS_AREA_LENGTH_SHORT		5792
92#define SIS_AREA_UNIT			(5792 / 32)
93
94struct sis_ts_data {
95	struct i2c_client *client;
96	struct input_dev *input;
97
98	struct gpio_desc *attn_gpio;
99	struct gpio_desc *reset_gpio;
100
101	u8 packet[SIS_MAX_PACKET_SIZE];
102};
103
104static int sis_read_packet(struct i2c_client *client, u8 *buf,
105			   unsigned int *num_contacts,
106			   unsigned int *contact_size)
107{
108	int count_idx;
109	int ret;
110	u16 len;
111	u16 crc, pkg_crc;
112	u8 report_id;
113
114	ret = i2c_master_recv(client, buf, SIS_MAX_PACKET_SIZE);
115	if (ret <= 0)
116		return -EIO;
117
118	len = get_unaligned_le16(&buf[SIS_PKT_LEN_OFFSET]);
119	if (len > SIS_MAX_PACKET_SIZE) {
120		dev_err(&client->dev,
121			"%s: invalid packet length (%d vs %d)\n",
122			__func__, len, SIS_MAX_PACKET_SIZE);
123		return -E2BIG;
124	}
125
126	if (len < 10)
127		return -EINVAL;
128
129	report_id = buf[SIS_PKT_REPORT_OFFSET];
130	count_idx  = len - 1;
131	*contact_size = SIS_BASE_LEN_PER_CONTACT;
132
133	if (report_id != SIS_ALL_IN_ONE_PACKAGE) {
134		if (SIS_PKT_IS_TOUCH(report_id)) {
135			/*
136			 * Calculate CRC ignoring packet length
137			 * in the beginning and CRC transmitted
138			 * at the end of the packet.
139			 */
140			crc = crc_itu_t(0, buf + 2, len - 2 - 2);
141			pkg_crc = get_unaligned_le16(&buf[len - 2]);
142
143			if (crc != pkg_crc) {
144				dev_err(&client->dev,
145					"%s: CRC Error (%d vs %d)\n",
146					__func__, crc, pkg_crc);
147				return -EINVAL;
148			}
149
150			count_idx -= 2;
151
152		} else if (!SIS_PKT_IS_HIDI2C(report_id)) {
153			dev_err(&client->dev,
154				"%s: invalid packet ID %#02x\n",
155				__func__, report_id);
156			return -EINVAL;
157		}
158
159		if (SIS_PKT_HAS_SCANTIME(report_id))
160			count_idx -= SIS_SCAN_TIME_LEN;
161
162		if (SIS_PKT_HAS_AREA(report_id))
163			*contact_size += SIS_AREA_LEN_PER_CONTACT;
164		if (SIS_PKT_HAS_PRESSURE(report_id))
165			*contact_size += SIS_PRESSURE_LEN_PER_CONTACT;
166	}
167
168	*num_contacts = buf[count_idx];
169	return 0;
170}
171
172static int sis_ts_report_contact(struct sis_ts_data *ts, const u8 *data, u8 id)
173{
174	struct input_dev *input = ts->input;
175	int slot;
176	u8 status = data[SIS_CONTACT_STATUS_OFFSET];
177	u8 pressure;
178	u8 height, width;
179	u16 x, y;
180
181	if (status != SIS_STATUS_DOWN && status != SIS_STATUS_UP) {
182		dev_err(&ts->client->dev, "Unexpected touch status: %#02x\n",
183			data[SIS_CONTACT_STATUS_OFFSET]);
184		return -EINVAL;
185	}
186
187	slot = input_mt_get_slot_by_key(input, data[SIS_CONTACT_ID_OFFSET]);
188	if (slot < 0)
189		return -ENOENT;
190
191	input_mt_slot(input, slot);
192	input_mt_report_slot_state(input, MT_TOOL_FINGER,
193				   status == SIS_STATUS_DOWN);
194
195	if (status == SIS_STATUS_DOWN) {
196		pressure = height = width = 1;
197		if (id != SIS_ALL_IN_ONE_PACKAGE) {
198			if (SIS_PKT_HAS_AREA(id)) {
199				width = data[SIS_CONTACT_WIDTH_OFFSET];
200				height = data[SIS_CONTACT_HEIGHT_OFFSET];
201			}
202
203			if (SIS_PKT_HAS_PRESSURE(id))
204				pressure =
205					data[SIS_CONTACT_PRESSURE_OFFSET(id)];
206		}
207
208		x = get_unaligned_le16(&data[SIS_CONTACT_X_OFFSET]);
209		y = get_unaligned_le16(&data[SIS_CONTACT_Y_OFFSET]);
210
211		input_report_abs(input, ABS_MT_TOUCH_MAJOR,
212				 width * SIS_AREA_UNIT);
213		input_report_abs(input, ABS_MT_TOUCH_MINOR,
214				 height * SIS_AREA_UNIT);
215		input_report_abs(input, ABS_MT_PRESSURE, pressure);
216		input_report_abs(input, ABS_MT_POSITION_X, x);
217		input_report_abs(input, ABS_MT_POSITION_Y, y);
218	}
219
220	return 0;
221}
222
223static void sis_ts_handle_packet(struct sis_ts_data *ts)
224{
225	const u8 *contact;
226	unsigned int num_to_report = 0;
227	unsigned int num_contacts;
228	unsigned int num_reported;
229	unsigned int contact_size;
230	int error;
231	u8 report_id;
232
233	do {
234		error = sis_read_packet(ts->client, ts->packet,
235					&num_contacts, &contact_size);
236		if (error)
237			break;
238
239		if (num_to_report == 0) {
240			num_to_report = num_contacts;
241		} else if (num_contacts != 0) {
242			dev_err(&ts->client->dev,
243				"%s: nonzero (%d) point count in tail packet\n",
244				__func__, num_contacts);
245			break;
246		}
247
248		report_id = ts->packet[SIS_PKT_REPORT_OFFSET];
249		contact = &ts->packet[SIS_PKT_CONTACT_OFFSET];
250		num_reported = 0;
251
252		while (num_to_report > 0) {
253			error = sis_ts_report_contact(ts, contact, report_id);
254			if (error)
255				break;
256
257			contact += contact_size;
258			num_to_report--;
259			num_reported++;
260
261			if (report_id != SIS_ALL_IN_ONE_PACKAGE &&
262			    num_reported >= 5) {
263				/*
264				 * The remainder of contacts is sent
265				 * in the 2nd packet.
266				 */
267				break;
268			}
269		}
270	} while (num_to_report > 0);
271
272	input_mt_sync_frame(ts->input);
273	input_sync(ts->input);
274}
275
276static irqreturn_t sis_ts_irq_handler(int irq, void *dev_id)
277{
278	struct sis_ts_data *ts = dev_id;
279
280	do {
281		sis_ts_handle_packet(ts);
282	} while (ts->attn_gpio && gpiod_get_value_cansleep(ts->attn_gpio));
283
284	return IRQ_HANDLED;
285}
286
287static void sis_ts_reset(struct sis_ts_data *ts)
288{
289	if (ts->reset_gpio) {
290		/* Get out of reset */
291		usleep_range(1000, 2000);
292		gpiod_set_value(ts->reset_gpio, 1);
293		usleep_range(1000, 2000);
294		gpiod_set_value(ts->reset_gpio, 0);
295		msleep(100);
296	}
297}
298
299static int sis_ts_probe(struct i2c_client *client)
300{
301	struct sis_ts_data *ts;
302	struct input_dev *input;
303	int error;
304
305	ts = devm_kzalloc(&client->dev, sizeof(*ts), GFP_KERNEL);
306	if (!ts)
307		return -ENOMEM;
308
309	ts->client = client;
310
311	ts->attn_gpio = devm_gpiod_get_optional(&client->dev,
312						"attn", GPIOD_IN);
313	if (IS_ERR(ts->attn_gpio))
314		return dev_err_probe(&client->dev, PTR_ERR(ts->attn_gpio),
315				     "Failed to get attention GPIO\n");
316
317	ts->reset_gpio = devm_gpiod_get_optional(&client->dev,
318						 "reset", GPIOD_OUT_LOW);
319	if (IS_ERR(ts->reset_gpio))
320		return dev_err_probe(&client->dev, PTR_ERR(ts->reset_gpio),
321				     "Failed to get reset GPIO\n");
322
323	sis_ts_reset(ts);
324
325	ts->input = input = devm_input_allocate_device(&client->dev);
326	if (!input) {
327		dev_err(&client->dev, "Failed to allocate input device\n");
328		return -ENOMEM;
329	}
330
331	input->name = "SiS Touchscreen";
332	input->id.bustype = BUS_I2C;
333
334	input_set_abs_params(input, ABS_MT_POSITION_X, 0, SIS_MAX_X, 0, 0);
335	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, SIS_MAX_Y, 0, 0);
336	input_set_abs_params(input, ABS_MT_PRESSURE, 0, SIS_MAX_PRESSURE, 0, 0);
337	input_set_abs_params(input, ABS_MT_TOUCH_MAJOR,
338			     0, SIS_AREA_LENGTH_LONGER, 0, 0);
339	input_set_abs_params(input, ABS_MT_TOUCH_MINOR,
340			     0, SIS_AREA_LENGTH_SHORT, 0, 0);
341
342	error = input_mt_init_slots(input, SIS_MAX_FINGERS, INPUT_MT_DIRECT);
343	if (error) {
344		dev_err(&client->dev,
345			"Failed to initialize MT slots: %d\n", error);
346		return error;
347	}
348
349	error = devm_request_threaded_irq(&client->dev, client->irq,
350					  NULL, sis_ts_irq_handler,
351					  IRQF_ONESHOT,
352					  client->name, ts);
353	if (error) {
354		dev_err(&client->dev, "Failed to request IRQ: %d\n", error);
355		return error;
356	}
357
358	error = input_register_device(ts->input);
359	if (error) {
360		dev_err(&client->dev,
361			"Failed to register input device: %d\n", error);
362		return error;
363	}
364
365	return 0;
366}
367
368#ifdef CONFIG_OF
369static const struct of_device_id sis_ts_dt_ids[] = {
370	{ .compatible = "sis,9200-ts" },
371	{ /* sentinel */ }
372};
373MODULE_DEVICE_TABLE(of, sis_ts_dt_ids);
374#endif
375
376static const struct i2c_device_id sis_ts_id[] = {
377	{ SIS_I2C_NAME,	0 },
378	{ "9200-ts",	0 },
379	{ /* sentinel */  }
380};
381MODULE_DEVICE_TABLE(i2c, sis_ts_id);
382
383static struct i2c_driver sis_ts_driver = {
384	.driver = {
385		.name	= SIS_I2C_NAME,
386		.of_match_table = of_match_ptr(sis_ts_dt_ids),
387	},
388	.probe		= sis_ts_probe,
389	.id_table	= sis_ts_id,
390};
391module_i2c_driver(sis_ts_driver);
392
393MODULE_DESCRIPTION("SiS 9200 Family Touchscreen Driver");
394MODULE_LICENSE("GPL v2");
395MODULE_AUTHOR("Mika Penttil�� <mika.penttila@nextfour.com>");
396