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 	bool running;
32 };
33 
34 #define EETI_TS_BITDEPTH	(11)
35 #define EETI_MAXVAL		((1 << (EETI_TS_BITDEPTH + 1)) - 1)
36 
37 #define REPORT_BIT_PRESSED	BIT(0)
38 #define REPORT_BIT_AD0		BIT(1)
39 #define REPORT_BIT_AD1		BIT(2)
40 #define REPORT_BIT_HAS_PRESSURE	BIT(6)
41 #define REPORT_RES_BITS(v)	(((v) >> 1) + EETI_TS_BITDEPTH)
42 
43 static void eeti_ts_report_event(struct eeti_ts *eeti, u8 *buf)
44 {
45 	unsigned int res;
46 	u16 x, y;
47 
48 	res = REPORT_RES_BITS(buf[0] & (REPORT_BIT_AD0 | REPORT_BIT_AD1));
49 
50 	x = get_unaligned_be16(&buf[1]);
51 	y = get_unaligned_be16(&buf[3]);
52 
53 	/* fix the range to 11 bits */
54 	x >>= res - EETI_TS_BITDEPTH;
55 	y >>= res - EETI_TS_BITDEPTH;
56 
57 	if (buf[0] & REPORT_BIT_HAS_PRESSURE)
58 		input_report_abs(eeti->input, ABS_PRESSURE, buf[5]);
59 
60 	touchscreen_report_pos(eeti->input, &eeti->props, x, y, false);
61 	input_report_key(eeti->input, BTN_TOUCH, buf[0] & REPORT_BIT_PRESSED);
62 	input_sync(eeti->input);
63 }
64 
65 static irqreturn_t eeti_ts_isr(int irq, void *dev_id)
66 {
67 	struct eeti_ts *eeti = dev_id;
68 	int len;
69 	int error;
70 	char buf[6];
71 
72 	do {
73 		len = i2c_master_recv(eeti->client, buf, sizeof(buf));
74 		if (len != sizeof(buf)) {
75 			error = len < 0 ? len : -EIO;
76 			dev_err(&eeti->client->dev,
77 				"failed to read touchscreen data: %d\n",
78 				error);
79 			break;
80 		}
81 
82 		if (buf[0] & 0x80) {
83 			/* Motion packet */
84 			eeti_ts_report_event(eeti, buf);
85 		}
86 	} while (eeti->running &&
87 		 eeti->attn_gpio && gpiod_get_value_cansleep(eeti->attn_gpio));
88 
89 	return IRQ_HANDLED;
90 }
91 
92 static void eeti_ts_start(struct eeti_ts *eeti)
93 {
94 	eeti->running = true;
95 	wmb();
96 	enable_irq(eeti->client->irq);
97 }
98 
99 static void eeti_ts_stop(struct eeti_ts *eeti)
100 {
101 	eeti->running = false;
102 	wmb();
103 	disable_irq(eeti->client->irq);
104 }
105 
106 static int eeti_ts_open(struct input_dev *dev)
107 {
108 	struct eeti_ts *eeti = input_get_drvdata(dev);
109 
110 	eeti_ts_start(eeti);
111 
112 	return 0;
113 }
114 
115 static void eeti_ts_close(struct input_dev *dev)
116 {
117 	struct eeti_ts *eeti = input_get_drvdata(dev);
118 
119 	eeti_ts_stop(eeti);
120 }
121 
122 static int eeti_ts_probe(struct i2c_client *client,
123 			 const struct i2c_device_id *idp)
124 {
125 	struct device *dev = &client->dev;
126 	struct eeti_ts *eeti;
127 	struct input_dev *input;
128 	int error;
129 
130 	/*
131 	 * In contrast to what's described in the datasheet, there seems
132 	 * to be no way of probing the presence of that device using I2C
133 	 * commands. So we need to blindly believe it is there, and wait
134 	 * for interrupts to occur.
135 	 */
136 
137 	eeti = devm_kzalloc(dev, sizeof(*eeti), GFP_KERNEL);
138 	if (!eeti) {
139 		dev_err(dev, "failed to allocate driver data\n");
140 		return -ENOMEM;
141 	}
142 
143 	input = devm_input_allocate_device(dev);
144 	if (!input) {
145 		dev_err(dev, "Failed to allocate input device.\n");
146 		return -ENOMEM;
147 	}
148 
149 	input_set_capability(input, EV_KEY, BTN_TOUCH);
150 
151 	input_set_abs_params(input, ABS_X, 0, EETI_MAXVAL, 0, 0);
152 	input_set_abs_params(input, ABS_Y, 0, EETI_MAXVAL, 0, 0);
153 	input_set_abs_params(input, ABS_PRESSURE, 0, 0xff, 0, 0);
154 
155 	touchscreen_parse_properties(input, false, &eeti->props);
156 
157 	input->name = client->name;
158 	input->id.bustype = BUS_I2C;
159 	input->open = eeti_ts_open;
160 	input->close = eeti_ts_close;
161 
162 	eeti->client = client;
163 	eeti->input = input;
164 
165 	eeti->attn_gpio = devm_gpiod_get_optional(dev, "attn", GPIOD_IN);
166 	if (IS_ERR(eeti->attn_gpio))
167 		return PTR_ERR(eeti->attn_gpio);
168 
169 	i2c_set_clientdata(client, eeti);
170 	input_set_drvdata(input, eeti);
171 
172 	error = devm_request_threaded_irq(dev, client->irq,
173 					  NULL, eeti_ts_isr,
174 					  IRQF_ONESHOT,
175 					  client->name, eeti);
176 	if (error) {
177 		dev_err(dev, "Unable to request touchscreen IRQ: %d\n",
178 			error);
179 		return error;
180 	}
181 
182 	/*
183 	 * Disable the device for now. It will be enabled once the
184 	 * input device is opened.
185 	 */
186 	eeti_ts_stop(eeti);
187 
188 	error = input_register_device(input);
189 	if (error)
190 		return error;
191 
192 	return 0;
193 }
194 
195 static int __maybe_unused eeti_ts_suspend(struct device *dev)
196 {
197 	struct i2c_client *client = to_i2c_client(dev);
198 	struct eeti_ts *eeti = i2c_get_clientdata(client);
199 	struct input_dev *input_dev = eeti->input;
200 
201 	mutex_lock(&input_dev->mutex);
202 
203 	if (input_dev->users)
204 		eeti_ts_stop(eeti);
205 
206 	mutex_unlock(&input_dev->mutex);
207 
208 	if (device_may_wakeup(&client->dev))
209 		enable_irq_wake(client->irq);
210 
211 	return 0;
212 }
213 
214 static int __maybe_unused eeti_ts_resume(struct device *dev)
215 {
216 	struct i2c_client *client = to_i2c_client(dev);
217 	struct eeti_ts *eeti = i2c_get_clientdata(client);
218 	struct input_dev *input_dev = eeti->input;
219 
220 	if (device_may_wakeup(&client->dev))
221 		disable_irq_wake(client->irq);
222 
223 	mutex_lock(&input_dev->mutex);
224 
225 	if (input_dev->users)
226 		eeti_ts_start(eeti);
227 
228 	mutex_unlock(&input_dev->mutex);
229 
230 	return 0;
231 }
232 
233 static SIMPLE_DEV_PM_OPS(eeti_ts_pm, eeti_ts_suspend, eeti_ts_resume);
234 
235 static const struct i2c_device_id eeti_ts_id[] = {
236 	{ "eeti_ts", 0 },
237 	{ }
238 };
239 MODULE_DEVICE_TABLE(i2c, eeti_ts_id);
240 
241 #ifdef CONFIG_OF
242 static const struct of_device_id of_eeti_ts_match[] = {
243 	{ .compatible = "eeti,exc3000-i2c", },
244 	{ }
245 };
246 #endif
247 
248 static struct i2c_driver eeti_ts_driver = {
249 	.driver = {
250 		.name = "eeti_ts",
251 		.pm = &eeti_ts_pm,
252 		.of_match_table = of_match_ptr(of_eeti_ts_match),
253 	},
254 	.probe = eeti_ts_probe,
255 	.id_table = eeti_ts_id,
256 };
257 
258 module_i2c_driver(eeti_ts_driver);
259 
260 MODULE_DESCRIPTION("EETI Touchscreen driver");
261 MODULE_AUTHOR("Daniel Mack <daniel@zonque.org>");
262 MODULE_LICENSE("GPL");
263