1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Driver for I2C connected EETI EXC3000 multiple touch controller
  4 *
  5 * Copyright (C) 2017 Ahmet Inan <inan@distec.de>
  6 *
  7 * minimal implementation based on egalax_ts.c and egalax_i2c.c
  8 */
  9
 10#include <linux/bitops.h>
 11#include <linux/device.h>
 12#include <linux/i2c.h>
 13#include <linux/input.h>
 14#include <linux/input/mt.h>
 15#include <linux/input/touchscreen.h>
 16#include <linux/interrupt.h>
 17#include <linux/module.h>
 18#include <linux/of.h>
 19#include <linux/timer.h>
 20#include <asm/unaligned.h>
 21
 22#define EXC3000_NUM_SLOTS		10
 23#define EXC3000_SLOTS_PER_FRAME		5
 24#define EXC3000_LEN_FRAME		66
 25#define EXC3000_LEN_POINT		10
 26#define EXC3000_MT_EVENT		6
 27#define EXC3000_TIMEOUT_MS		100
 28
 29struct exc3000_data {
 30	struct i2c_client *client;
 31	struct input_dev *input;
 32	struct touchscreen_properties prop;
 33	struct timer_list timer;
 34	u8 buf[2 * EXC3000_LEN_FRAME];
 35};
 36
 37static void exc3000_report_slots(struct input_dev *input,
 38				 struct touchscreen_properties *prop,
 39				 const u8 *buf, int num)
 40{
 41	for (; num--; buf += EXC3000_LEN_POINT) {
 42		if (buf[0] & BIT(0)) {
 43			input_mt_slot(input, buf[1]);
 44			input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
 45			touchscreen_report_pos(input, prop,
 46					       get_unaligned_le16(buf + 2),
 47					       get_unaligned_le16(buf + 4),
 48					       true);
 49		}
 50	}
 51}
 52
 53static void exc3000_timer(struct timer_list *t)
 54{
 55	struct exc3000_data *data = from_timer(data, t, timer);
 56
 57	input_mt_sync_frame(data->input);
 58	input_sync(data->input);
 59}
 60
 61static int exc3000_read_frame(struct i2c_client *client, u8 *buf)
 62{
 63	int ret;
 64
 65	ret = i2c_master_send(client, "'", 2);
 66	if (ret < 0)
 67		return ret;
 68
 69	if (ret != 2)
 70		return -EIO;
 71
 72	ret = i2c_master_recv(client, buf, EXC3000_LEN_FRAME);
 73	if (ret < 0)
 74		return ret;
 75
 76	if (ret != EXC3000_LEN_FRAME)
 77		return -EIO;
 78
 79	if (get_unaligned_le16(buf) != EXC3000_LEN_FRAME ||
 80			buf[2] != EXC3000_MT_EVENT)
 81		return -EINVAL;
 82
 83	return 0;
 84}
 85
 86static int exc3000_read_data(struct i2c_client *client,
 87			     u8 *buf, int *n_slots)
 88{
 89	int error;
 90
 91	error = exc3000_read_frame(client, buf);
 92	if (error)
 93		return error;
 94
 95	*n_slots = buf[3];
 96	if (!*n_slots || *n_slots > EXC3000_NUM_SLOTS)
 97		return -EINVAL;
 98
 99	if (*n_slots > EXC3000_SLOTS_PER_FRAME) {
100		/* Read 2nd frame to get the rest of the contacts. */
101		error = exc3000_read_frame(client, buf + EXC3000_LEN_FRAME);
102		if (error)
103			return error;
104
105		/* 2nd chunk must have number of contacts set to 0. */
106		if (buf[EXC3000_LEN_FRAME + 3] != 0)
107			return -EINVAL;
108	}
109
110	return 0;
111}
112
113static irqreturn_t exc3000_interrupt(int irq, void *dev_id)
114{
115	struct exc3000_data *data = dev_id;
116	struct input_dev *input = data->input;
117	u8 *buf = data->buf;
118	int slots, total_slots;
119	int error;
120
121	error = exc3000_read_data(data->client, buf, &total_slots);
122	if (error) {
123		/* Schedule a timer to release "stuck" contacts */
124		mod_timer(&data->timer,
125			  jiffies + msecs_to_jiffies(EXC3000_TIMEOUT_MS));
126		goto out;
127	}
128
129	/*
130	 * We read full state successfully, no contacts will be "stuck".
131	 */
132	del_timer_sync(&data->timer);
133
134	while (total_slots > 0) {
135		slots = min(total_slots, EXC3000_SLOTS_PER_FRAME);
136		exc3000_report_slots(input, &data->prop, buf + 4, slots);
137		total_slots -= slots;
138		buf += EXC3000_LEN_FRAME;
139	}
140
141	input_mt_sync_frame(input);
142	input_sync(input);
143
144out:
145	return IRQ_HANDLED;
146}
147
148static int exc3000_probe(struct i2c_client *client,
149			 const struct i2c_device_id *id)
150{
151	struct exc3000_data *data;
152	struct input_dev *input;
153	int error;
154
155	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
156	if (!data)
157		return -ENOMEM;
158
159	data->client = client;
160	timer_setup(&data->timer, exc3000_timer, 0);
161
162	input = devm_input_allocate_device(&client->dev);
163	if (!input)
164		return -ENOMEM;
165
166	data->input = input;
167
168	input->name = "EETI EXC3000 Touch Screen";
169	input->id.bustype = BUS_I2C;
170
171	input_set_abs_params(input, ABS_MT_POSITION_X, 0, 4095, 0, 0);
172	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, 4095, 0, 0);
173	touchscreen_parse_properties(input, true, &data->prop);
174
175	error = input_mt_init_slots(input, EXC3000_NUM_SLOTS,
176				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
177	if (error)
178		return error;
179
180	error = input_register_device(input);
181	if (error)
182		return error;
183
184	error = devm_request_threaded_irq(&client->dev, client->irq,
185					  NULL, exc3000_interrupt, IRQF_ONESHOT,
186					  client->name, data);
187	if (error)
188		return error;
189
190	return 0;
191}
192
193static const struct i2c_device_id exc3000_id[] = {
194	{ "exc3000", 0 },
195	{ }
196};
197MODULE_DEVICE_TABLE(i2c, exc3000_id);
198
199#ifdef CONFIG_OF
200static const struct of_device_id exc3000_of_match[] = {
201	{ .compatible = "eeti,exc3000" },
202	{ }
203};
204MODULE_DEVICE_TABLE(of, exc3000_of_match);
205#endif
206
207static struct i2c_driver exc3000_driver = {
208	.driver = {
209		.name	= "exc3000",
210		.of_match_table = of_match_ptr(exc3000_of_match),
211	},
212	.id_table	= exc3000_id,
213	.probe		= exc3000_probe,
214};
215
216module_i2c_driver(exc3000_driver);
217
218MODULE_AUTHOR("Ahmet Inan <inan@distec.de>");
219MODULE_DESCRIPTION("I2C connected EETI EXC3000 multiple touch controller driver");
220MODULE_LICENSE("GPL v2");