1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Driver for Himax hx83112b touchscreens
4  *
5  * Copyright (C) 2022 Job Noorman <job@noorman.info>
6  *
7  * This code is based on "Himax Android Driver Sample Code for QCT platform":
8  *
9  * Copyright (C) 2017 Himax Corporation.
10  */
11 
12 #include <linux/delay.h>
13 #include <linux/err.h>
14 #include <linux/gpio/consumer.h>
15 #include <linux/i2c.h>
16 #include <linux/input.h>
17 #include <linux/input/mt.h>
18 #include <linux/input/touchscreen.h>
19 #include <linux/interrupt.h>
20 #include <linux/kernel.h>
21 #include <linux/regmap.h>
22 
23 #define HIMAX_ID_83112B			0x83112b
24 
25 #define HIMAX_MAX_POINTS		10
26 
27 #define HIMAX_REG_CFG_SET_ADDR		0x00
28 #define HIMAX_REG_CFG_INIT_READ		0x0c
29 #define HIMAX_REG_CFG_READ_VALUE	0x08
30 #define HIMAX_REG_READ_EVENT		0x30
31 
32 #define HIMAX_CFG_PRODUCT_ID		0x900000d0
33 
34 #define HIMAX_INVALID_COORD		0xffff
35 
36 struct himax_event_point {
37 	__be16 x;
38 	__be16 y;
39 } __packed;
40 
41 struct himax_event {
42 	struct himax_event_point points[HIMAX_MAX_POINTS];
43 	u8 majors[HIMAX_MAX_POINTS];
44 	u8 pad0[2];
45 	u8 num_points;
46 	u8 pad1[2];
47 	u8 checksum_fix;
48 } __packed;
49 
50 static_assert(sizeof(struct himax_event) == 56);
51 
52 struct himax_ts_data {
53 	struct gpio_desc *gpiod_rst;
54 	struct input_dev *input_dev;
55 	struct i2c_client *client;
56 	struct regmap *regmap;
57 	struct touchscreen_properties props;
58 };
59 
60 static const struct regmap_config himax_regmap_config = {
61 	.reg_bits = 8,
62 	.val_bits = 32,
63 	.val_format_endian = REGMAP_ENDIAN_LITTLE,
64 };
65 
66 static int himax_read_config(struct himax_ts_data *ts, u32 address, u32 *dst)
67 {
68 	int error;
69 
70 	error = regmap_write(ts->regmap, HIMAX_REG_CFG_SET_ADDR, address);
71 	if (error)
72 		return error;
73 
74 	error = regmap_write(ts->regmap, HIMAX_REG_CFG_INIT_READ, 0x0);
75 	if (error)
76 		return error;
77 
78 	error = regmap_read(ts->regmap, HIMAX_REG_CFG_READ_VALUE, dst);
79 	if (error)
80 		return error;
81 
82 	return 0;
83 }
84 
85 static void himax_reset(struct himax_ts_data *ts)
86 {
87 	gpiod_set_value_cansleep(ts->gpiod_rst, 1);
88 
89 	/* Delay copied from downstream driver */
90 	msleep(20);
91 	gpiod_set_value_cansleep(ts->gpiod_rst, 0);
92 
93 	/*
94 	 * The downstream driver doesn't contain this delay but is seems safer
95 	 * to include it. The range is just a guess that seems to work well.
96 	 */
97 	usleep_range(1000, 1100);
98 }
99 
100 static int himax_read_product_id(struct himax_ts_data *ts, u32 *product_id)
101 {
102 	int error;
103 
104 	error = himax_read_config(ts, HIMAX_CFG_PRODUCT_ID, product_id);
105 	if (error)
106 		return error;
107 
108 	*product_id >>= 8;
109 	return 0;
110 }
111 
112 static int himax_check_product_id(struct himax_ts_data *ts)
113 {
114 	int error;
115 	u32 product_id;
116 
117 	error = himax_read_product_id(ts, &product_id);
118 	if (error)
119 		return error;
120 
121 	dev_dbg(&ts->client->dev, "Product id: %x\n", product_id);
122 
123 	switch (product_id) {
124 	case HIMAX_ID_83112B:
125 		return 0;
126 
127 	default:
128 		dev_err(&ts->client->dev,
129 			"Unknown product id: %x\n", product_id);
130 		return -EINVAL;
131 	}
132 }
133 
134 static int himax_input_register(struct himax_ts_data *ts)
135 {
136 	int error;
137 
138 	ts->input_dev = devm_input_allocate_device(&ts->client->dev);
139 	if (!ts->input_dev) {
140 		dev_err(&ts->client->dev, "Failed to allocate input device\n");
141 		return -ENOMEM;
142 	}
143 
144 	ts->input_dev->name = "Himax Touchscreen";
145 
146 	input_set_capability(ts->input_dev, EV_ABS, ABS_MT_POSITION_X);
147 	input_set_capability(ts->input_dev, EV_ABS, ABS_MT_POSITION_Y);
148 	input_set_abs_params(ts->input_dev, ABS_MT_WIDTH_MAJOR, 0, 200, 0, 0);
149 	input_set_abs_params(ts->input_dev, ABS_MT_TOUCH_MAJOR, 0, 200, 0, 0);
150 
151 	touchscreen_parse_properties(ts->input_dev, true, &ts->props);
152 
153 	error = input_mt_init_slots(ts->input_dev, HIMAX_MAX_POINTS,
154 				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
155 	if (error) {
156 		dev_err(&ts->client->dev,
157 			"Failed to initialize MT slots: %d\n", error);
158 		return error;
159 	}
160 
161 	error = input_register_device(ts->input_dev);
162 	if (error) {
163 		dev_err(&ts->client->dev,
164 			"Failed to register input device: %d\n", error);
165 		return error;
166 	}
167 
168 	return 0;
169 }
170 
171 static u8 himax_event_get_num_points(const struct himax_event *event)
172 {
173 	if (event->num_points == 0xff)
174 		return 0;
175 	else
176 		return event->num_points & 0x0f;
177 }
178 
179 static bool himax_process_event_point(struct himax_ts_data *ts,
180 				      const struct himax_event *event,
181 				      int point_index)
182 {
183 	const struct himax_event_point *point = &event->points[point_index];
184 	u16 x = be16_to_cpu(point->x);
185 	u16 y = be16_to_cpu(point->y);
186 	u8 w = event->majors[point_index];
187 
188 	if (x == HIMAX_INVALID_COORD || y == HIMAX_INVALID_COORD)
189 		return false;
190 
191 	input_mt_slot(ts->input_dev, point_index);
192 	input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER, true);
193 	touchscreen_report_pos(ts->input_dev, &ts->props, x, y, true);
194 	input_report_abs(ts->input_dev, ABS_MT_TOUCH_MAJOR, w);
195 	input_report_abs(ts->input_dev, ABS_MT_WIDTH_MAJOR, w);
196 	return true;
197 }
198 
199 static void himax_process_event(struct himax_ts_data *ts,
200 				const struct himax_event *event)
201 {
202 	int i;
203 	int num_points_left = himax_event_get_num_points(event);
204 
205 	for (i = 0; i < HIMAX_MAX_POINTS && num_points_left > 0; i++) {
206 		if (himax_process_event_point(ts, event, i))
207 			num_points_left--;
208 	}
209 
210 	input_mt_sync_frame(ts->input_dev);
211 	input_sync(ts->input_dev);
212 }
213 
214 static bool himax_verify_checksum(struct himax_ts_data *ts,
215 				  const struct himax_event *event)
216 {
217 	u8 *data = (u8 *)event;
218 	int i;
219 	u16 checksum = 0;
220 
221 	for (i = 0; i < sizeof(*event); i++)
222 		checksum += data[i];
223 
224 	if ((checksum & 0x00ff) != 0) {
225 		dev_err(&ts->client->dev, "Wrong event checksum: %04x\n",
226 			checksum);
227 		return false;
228 	}
229 
230 	return true;
231 }
232 
233 static int himax_handle_input(struct himax_ts_data *ts)
234 {
235 	int error;
236 	struct himax_event event;
237 
238 	error = regmap_raw_read(ts->regmap, HIMAX_REG_READ_EVENT, &event,
239 				sizeof(event));
240 	if (error) {
241 		dev_err(&ts->client->dev, "Failed to read input event: %d\n",
242 			error);
243 		return error;
244 	}
245 
246 	/*
247 	 * Only process the current event when it has a valid checksum but
248 	 * don't consider it a fatal error when it doesn't.
249 	 */
250 	if (himax_verify_checksum(ts, &event))
251 		himax_process_event(ts, &event);
252 
253 	return 0;
254 }
255 
256 static irqreturn_t himax_irq_handler(int irq, void *dev_id)
257 {
258 	int error;
259 	struct himax_ts_data *ts = dev_id;
260 
261 	error = himax_handle_input(ts);
262 	if (error)
263 		return IRQ_NONE;
264 
265 	return IRQ_HANDLED;
266 }
267 
268 static int himax_probe(struct i2c_client *client)
269 {
270 	int error;
271 	struct device *dev = &client->dev;
272 	struct himax_ts_data *ts;
273 
274 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
275 		dev_err(dev, "I2C check functionality failed\n");
276 		return -ENXIO;
277 	}
278 
279 	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
280 	if (!ts)
281 		return -ENOMEM;
282 
283 	i2c_set_clientdata(client, ts);
284 	ts->client = client;
285 
286 	ts->regmap = devm_regmap_init_i2c(client, &himax_regmap_config);
287 	error = PTR_ERR_OR_ZERO(ts->regmap);
288 	if (error) {
289 		dev_err(dev, "Failed to initialize regmap: %d\n", error);
290 		return error;
291 	}
292 
293 	ts->gpiod_rst = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
294 	error = PTR_ERR_OR_ZERO(ts->gpiod_rst);
295 	if (error) {
296 		dev_err(dev, "Failed to get reset GPIO: %d\n", error);
297 		return error;
298 	}
299 
300 	himax_reset(ts);
301 
302 	error = himax_check_product_id(ts);
303 	if (error)
304 		return error;
305 
306 	error = himax_input_register(ts);
307 	if (error)
308 		return error;
309 
310 	error = devm_request_threaded_irq(dev, client->irq, NULL,
311 					  himax_irq_handler, IRQF_ONESHOT,
312 					  client->name, ts);
313 	if (error)
314 		return error;
315 
316 	return 0;
317 }
318 
319 static int himax_suspend(struct device *dev)
320 {
321 	struct himax_ts_data *ts = dev_get_drvdata(dev);
322 
323 	disable_irq(ts->client->irq);
324 	return 0;
325 }
326 
327 static int himax_resume(struct device *dev)
328 {
329 	struct himax_ts_data *ts = dev_get_drvdata(dev);
330 
331 	enable_irq(ts->client->irq);
332 	return 0;
333 }
334 
335 static DEFINE_SIMPLE_DEV_PM_OPS(himax_pm_ops, himax_suspend, himax_resume);
336 
337 static const struct i2c_device_id himax_ts_id[] = {
338 	{ "hx83112b", 0 },
339 	{ /* sentinel */ }
340 };
341 MODULE_DEVICE_TABLE(i2c, himax_ts_id);
342 
343 #ifdef CONFIG_OF
344 static const struct of_device_id himax_of_match[] = {
345 	{ .compatible = "himax,hx83112b" },
346 	{ /* sentinel */ }
347 };
348 MODULE_DEVICE_TABLE(of, himax_of_match);
349 #endif
350 
351 static struct i2c_driver himax_ts_driver = {
352 	.probe = himax_probe,
353 	.id_table = himax_ts_id,
354 	.driver = {
355 		.name = "Himax-hx83112b-TS",
356 		.of_match_table = of_match_ptr(himax_of_match),
357 		.pm = pm_sleep_ptr(&himax_pm_ops),
358 	},
359 };
360 module_i2c_driver(himax_ts_driver);
361 
362 MODULE_AUTHOR("Job Noorman <job@noorman.info>");
363 MODULE_DESCRIPTION("Himax hx83112b touchscreen driver");
364 MODULE_LICENSE("GPL");
365