1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Driver for Novatek i2c touchscreen controller as found on
4  * the Acer Iconia One 7 B1-750 tablet. The Touchscreen controller
5  * model-number is unknown. Android calls this a "NVT-ts" touchscreen,
6  * but that may apply to other Novatek controller models too.
7  *
8  * Copyright (c) 2023 Hans de Goede <hdegoede@redhat.com>
9  */
10 
11 #include <linux/delay.h>
12 #include <linux/gpio/consumer.h>
13 #include <linux/interrupt.h>
14 #include <linux/i2c.h>
15 #include <linux/input.h>
16 #include <linux/input/mt.h>
17 #include <linux/input/touchscreen.h>
18 #include <linux/module.h>
19 
20 #include <asm/unaligned.h>
21 
22 #define NVT_TS_TOUCH_START		0x00
23 #define NVT_TS_TOUCH_SIZE		6
24 
25 #define NVT_TS_PARAMETERS_START		0x78
26 /* These are offsets from NVT_TS_PARAMETERS_START */
27 #define NVT_TS_PARAMS_WIDTH		0x04
28 #define NVT_TS_PARAMS_HEIGHT		0x06
29 #define NVT_TS_PARAMS_MAX_TOUCH		0x09
30 #define NVT_TS_PARAMS_MAX_BUTTONS	0x0a
31 #define NVT_TS_PARAMS_IRQ_TYPE		0x0b
32 #define NVT_TS_PARAMS_WAKE_TYPE		0x0c
33 #define NVT_TS_PARAMS_CHIP_ID		0x0e
34 #define NVT_TS_PARAMS_SIZE		0x0f
35 
36 #define NVT_TS_SUPPORTED_WAKE_TYPE	0x05
37 #define NVT_TS_SUPPORTED_CHIP_ID	0x05
38 
39 #define NVT_TS_MAX_TOUCHES		10
40 #define NVT_TS_MAX_SIZE			4096
41 
42 #define NVT_TS_TOUCH_INVALID		0xff
43 #define NVT_TS_TOUCH_SLOT_SHIFT		3
44 #define NVT_TS_TOUCH_TYPE_MASK		GENMASK(2, 0)
45 #define NVT_TS_TOUCH_NEW		1
46 #define NVT_TS_TOUCH_UPDATE		2
47 #define NVT_TS_TOUCH_RELEASE		3
48 
49 static const int nvt_ts_irq_type[4] = {
50 	IRQF_TRIGGER_RISING,
51 	IRQF_TRIGGER_FALLING,
52 	IRQF_TRIGGER_LOW,
53 	IRQF_TRIGGER_HIGH
54 };
55 
56 struct nvt_ts_data {
57 	struct i2c_client *client;
58 	struct input_dev *input;
59 	struct gpio_desc *reset_gpio;
60 	struct touchscreen_properties prop;
61 	int max_touches;
62 	u8 buf[NVT_TS_TOUCH_SIZE * NVT_TS_MAX_TOUCHES];
63 };
64 
65 static int nvt_ts_read_data(struct i2c_client *client, u8 reg, u8 *data, int count)
66 {
67 	struct i2c_msg msg[2] = {
68 		{
69 			.addr = client->addr,
70 			.len = 1,
71 			.buf = &reg,
72 		},
73 		{
74 			.addr = client->addr,
75 			.flags = I2C_M_RD,
76 			.len = count,
77 			.buf = data,
78 		}
79 	};
80 	int ret;
81 
82 	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
83 	if (ret != ARRAY_SIZE(msg)) {
84 		dev_err(&client->dev, "Error reading from 0x%02x: %d\n", reg, ret);
85 		return (ret < 0) ? ret : -EIO;
86 	}
87 
88 	return 0;
89 }
90 
91 static irqreturn_t nvt_ts_irq(int irq, void *dev_id)
92 {
93 	struct nvt_ts_data *data = dev_id;
94 	struct device *dev = &data->client->dev;
95 	int i, error, slot, x, y;
96 	bool active;
97 	u8 *touch;
98 
99 	error = nvt_ts_read_data(data->client, NVT_TS_TOUCH_START, data->buf,
100 				 data->max_touches * NVT_TS_TOUCH_SIZE);
101 	if (error)
102 		return IRQ_HANDLED;
103 
104 	for (i = 0; i < data->max_touches; i++) {
105 		touch = &data->buf[i * NVT_TS_TOUCH_SIZE];
106 
107 		if (touch[0] == NVT_TS_TOUCH_INVALID)
108 			continue;
109 
110 		slot = touch[0] >> NVT_TS_TOUCH_SLOT_SHIFT;
111 		if (slot < 1 || slot > data->max_touches) {
112 			dev_warn(dev, "slot %d out of range, ignoring\n", slot);
113 			continue;
114 		}
115 
116 		switch (touch[0] & NVT_TS_TOUCH_TYPE_MASK) {
117 		case NVT_TS_TOUCH_NEW:
118 		case NVT_TS_TOUCH_UPDATE:
119 			active = true;
120 			break;
121 		case NVT_TS_TOUCH_RELEASE:
122 			active = false;
123 			break;
124 		default:
125 			dev_warn(dev, "slot %d unknown state %d\n", slot, touch[0] & 7);
126 			continue;
127 		}
128 
129 		slot--;
130 		x = (touch[1] << 4) | (touch[3] >> 4);
131 		y = (touch[2] << 4) | (touch[3] & 0x0f);
132 
133 		input_mt_slot(data->input, slot);
134 		input_mt_report_slot_state(data->input, MT_TOOL_FINGER, active);
135 		touchscreen_report_pos(data->input, &data->prop, x, y, true);
136 	}
137 
138 	input_mt_sync_frame(data->input);
139 	input_sync(data->input);
140 
141 	return IRQ_HANDLED;
142 }
143 
144 static int nvt_ts_start(struct input_dev *dev)
145 {
146 	struct nvt_ts_data *data = input_get_drvdata(dev);
147 
148 	enable_irq(data->client->irq);
149 	gpiod_set_value_cansleep(data->reset_gpio, 0);
150 
151 	return 0;
152 }
153 
154 static void nvt_ts_stop(struct input_dev *dev)
155 {
156 	struct nvt_ts_data *data = input_get_drvdata(dev);
157 
158 	disable_irq(data->client->irq);
159 	gpiod_set_value_cansleep(data->reset_gpio, 1);
160 }
161 
162 static int nvt_ts_suspend(struct device *dev)
163 {
164 	struct nvt_ts_data *data = i2c_get_clientdata(to_i2c_client(dev));
165 
166 	mutex_lock(&data->input->mutex);
167 	if (input_device_enabled(data->input))
168 		nvt_ts_stop(data->input);
169 	mutex_unlock(&data->input->mutex);
170 
171 	return 0;
172 }
173 
174 static int nvt_ts_resume(struct device *dev)
175 {
176 	struct nvt_ts_data *data = i2c_get_clientdata(to_i2c_client(dev));
177 
178 	mutex_lock(&data->input->mutex);
179 	if (input_device_enabled(data->input))
180 		nvt_ts_start(data->input);
181 	mutex_unlock(&data->input->mutex);
182 
183 	return 0;
184 }
185 
186 static DEFINE_SIMPLE_DEV_PM_OPS(nvt_ts_pm_ops, nvt_ts_suspend, nvt_ts_resume);
187 
188 static int nvt_ts_probe(struct i2c_client *client)
189 {
190 	struct device *dev = &client->dev;
191 	int error, width, height, irq_type;
192 	struct nvt_ts_data *data;
193 	struct input_dev *input;
194 
195 	if (!client->irq) {
196 		dev_err(dev, "Error no irq specified\n");
197 		return -EINVAL;
198 	}
199 
200 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
201 	if (!data)
202 		return -ENOMEM;
203 
204 	data->client = client;
205 	i2c_set_clientdata(client, data);
206 
207 	data->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
208 	error = PTR_ERR_OR_ZERO(data->reset_gpio);
209 	if (error) {
210 		dev_err(dev, "failed to request reset GPIO: %d\n", error);
211 		return error;
212 	}
213 
214 	/* Wait for controller to come out of reset before params read */
215 	msleep(100);
216 	error = nvt_ts_read_data(data->client, NVT_TS_PARAMETERS_START,
217 				 data->buf, NVT_TS_PARAMS_SIZE);
218 	gpiod_set_value_cansleep(data->reset_gpio, 1); /* Put back in reset */
219 	if (error)
220 		return error;
221 
222 	width  = get_unaligned_be16(&data->buf[NVT_TS_PARAMS_WIDTH]);
223 	height = get_unaligned_be16(&data->buf[NVT_TS_PARAMS_HEIGHT]);
224 	data->max_touches = data->buf[NVT_TS_PARAMS_MAX_TOUCH];
225 	irq_type = data->buf[NVT_TS_PARAMS_IRQ_TYPE];
226 
227 	if (width > NVT_TS_MAX_SIZE || height >= NVT_TS_MAX_SIZE ||
228 	    data->max_touches > NVT_TS_MAX_TOUCHES ||
229 	    irq_type >= ARRAY_SIZE(nvt_ts_irq_type) ||
230 	    data->buf[NVT_TS_PARAMS_WAKE_TYPE] != NVT_TS_SUPPORTED_WAKE_TYPE ||
231 	    data->buf[NVT_TS_PARAMS_CHIP_ID] != NVT_TS_SUPPORTED_CHIP_ID) {
232 		dev_err(dev, "Unsupported touchscreen parameters: %*ph\n",
233 			NVT_TS_PARAMS_SIZE, data->buf);
234 		return -EIO;
235 	}
236 
237 	dev_dbg(dev, "Detected %dx%d touchscreen with %d max touches\n",
238 		width, height, data->max_touches);
239 
240 	if (data->buf[NVT_TS_PARAMS_MAX_BUTTONS])
241 		dev_warn(dev, "Touchscreen buttons are not supported\n");
242 
243 	input = devm_input_allocate_device(dev);
244 	if (!input)
245 		return -ENOMEM;
246 
247 	input->name = client->name;
248 	input->id.bustype = BUS_I2C;
249 	input->open = nvt_ts_start;
250 	input->close = nvt_ts_stop;
251 
252 	input_set_abs_params(input, ABS_MT_POSITION_X, 0, width - 1, 0, 0);
253 	input_set_abs_params(input, ABS_MT_POSITION_Y, 0, height - 1, 0, 0);
254 	touchscreen_parse_properties(input, true, &data->prop);
255 
256 	error = input_mt_init_slots(input, data->max_touches,
257 				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
258 	if (error)
259 		return error;
260 
261 	data->input = input;
262 	input_set_drvdata(input, data);
263 
264 	error = devm_request_threaded_irq(dev, client->irq, NULL, nvt_ts_irq,
265 					  IRQF_ONESHOT | IRQF_NO_AUTOEN |
266 						nvt_ts_irq_type[irq_type],
267 					  client->name, data);
268 	if (error) {
269 		dev_err(dev, "failed to request irq: %d\n", error);
270 		return error;
271 	}
272 
273 	error = input_register_device(input);
274 	if (error) {
275 		dev_err(dev, "failed to request irq: %d\n", error);
276 		return error;
277 	}
278 
279 	return 0;
280 }
281 
282 static const struct i2c_device_id nvt_ts_i2c_id[] = {
283 	{ "NVT-ts" },
284 	{ }
285 };
286 MODULE_DEVICE_TABLE(i2c, nvt_ts_i2c_id);
287 
288 static struct i2c_driver nvt_ts_driver = {
289 	.driver = {
290 		.name	= "novatek-nvt-ts",
291 		.pm	= pm_sleep_ptr(&nvt_ts_pm_ops),
292 	},
293 	.probe = nvt_ts_probe,
294 	.id_table = nvt_ts_i2c_id,
295 };
296 
297 module_i2c_driver(nvt_ts_driver);
298 
299 MODULE_DESCRIPTION("Novatek NVT-ts touchscreen driver");
300 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
301 MODULE_LICENSE("GPL");
302