1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *  Driver for Hynitron cstxxx Touchscreen
4 *
5 *  Copyright (c) 2022 Chris Morgan <macromorgan@hotmail.com>
6 *
7 *  This code is based on hynitron_core.c authored by Hynitron.
8 *  Note that no datasheet was available, so much of these registers
9 *  are undocumented. This is essentially a cleaned-up version of the
10 *  vendor driver with support removed for hardware I cannot test and
11 *  device-specific functions replated with generic functions wherever
12 *  possible.
13 */
14
15#include <linux/delay.h>
16#include <linux/err.h>
17#include <linux/gpio/consumer.h>
18#include <linux/i2c.h>
19#include <linux/input.h>
20#include <linux/input/mt.h>
21#include <linux/input/touchscreen.h>
22#include <linux/mod_devicetable.h>
23#include <linux/module.h>
24#include <linux/property.h>
25#include <asm/unaligned.h>
26
27/* Per chip data */
28struct hynitron_ts_chip_data {
29	unsigned int max_touch_num;
30	u32 ic_chkcode;
31	int (*firmware_info)(struct i2c_client *client);
32	int (*bootloader_enter)(struct i2c_client *client);
33	int (*init_input)(struct i2c_client *client);
34	void (*report_touch)(struct i2c_client *client);
35};
36
37/* Data generic to all (supported and non-supported) controllers. */
38struct hynitron_ts_data {
39	const struct hynitron_ts_chip_data *chip;
40	struct i2c_client *client;
41	struct input_dev *input_dev;
42	struct touchscreen_properties prop;
43	struct gpio_desc *reset_gpio;
44};
45
46/*
47 * Since I have no datasheet, these values are guessed and/or assumed
48 * based on observation and testing.
49 */
50#define CST3XX_FIRMWARE_INFO_START_CMD		0x01d1
51#define CST3XX_FIRMWARE_INFO_END_CMD		0x09d1
52#define CST3XX_FIRMWARE_CHK_CODE_REG		0xfcd1
53#define CST3XX_FIRMWARE_VERSION_REG		0x08d2
54#define CST3XX_FIRMWARE_VER_INVALID_VAL		0xa5a5a5a5
55
56#define CST3XX_BOOTLDR_PROG_CMD			0xaa01a0
57#define CST3XX_BOOTLDR_PROG_CHK_REG		0x02a0
58#define CST3XX_BOOTLDR_CHK_VAL			0xac
59
60#define CST3XX_TOUCH_DATA_PART_REG		0x00d0
61#define CST3XX_TOUCH_DATA_FULL_REG		0x07d0
62#define CST3XX_TOUCH_DATA_CHK_VAL		0xab
63#define CST3XX_TOUCH_DATA_TOUCH_VAL		0x03
64#define CST3XX_TOUCH_DATA_STOP_CMD		0xab00d0
65#define CST3XX_TOUCH_COUNT_MASK			GENMASK(6, 0)
66
67
68/*
69 * Hard coded reset delay value of 20ms not IC dependent in
70 * vendor driver.
71 */
72static void hyn_reset_proc(struct i2c_client *client, int delay)
73{
74	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
75
76	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
77	msleep(20);
78	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
79	if (delay)
80		fsleep(delay * 1000);
81}
82
83static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
84{
85	struct i2c_client *client = dev_id;
86	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
87
88	ts_data->chip->report_touch(client);
89
90	return IRQ_HANDLED;
91}
92
93/*
94 * The vendor driver would retry twice before failing to read or write
95 * to the i2c device.
96 */
97
98static int cst3xx_i2c_write(struct i2c_client *client,
99			    unsigned char *buf, int len)
100{
101	int ret;
102	int retries = 0;
103
104	while (retries < 2) {
105		ret = i2c_master_send(client, buf, len);
106		if (ret == len)
107			return 0;
108		if (ret <= 0)
109			retries++;
110		else
111			break;
112	}
113
114	return ret < 0 ? ret : -EIO;
115}
116
117static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
118				    u8 *val, u16 len)
119{
120	__le16 buf = cpu_to_le16(reg);
121	struct i2c_msg msgs[] = {
122		{
123			.addr = client->addr,
124			.flags = 0,
125			.len = 2,
126			.buf = (u8 *)&buf,
127		},
128		{
129			.addr = client->addr,
130			.flags = I2C_M_RD,
131			.len = len,
132			.buf = val,
133		}
134	};
135	int err;
136	int ret;
137
138	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
139	if (ret == ARRAY_SIZE(msgs))
140		return 0;
141
142	err = ret < 0 ? ret : -EIO;
143	dev_err(&client->dev, "Error reading %d bytes from 0x%04x: %d (%d)\n",
144		len, reg, err, ret);
145
146	return err;
147}
148
149static int cst3xx_firmware_info(struct i2c_client *client)
150{
151	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
152	int err;
153	u32 tmp;
154	unsigned char buf[4];
155
156	/*
157	 * Tests suggest this command needed to read firmware regs.
158	 */
159	put_unaligned_le16(CST3XX_FIRMWARE_INFO_START_CMD, buf);
160	err = cst3xx_i2c_write(client, buf, 2);
161	if (err)
162		return err;
163
164	usleep_range(10000, 11000);
165
166	/*
167	 * Read register for check-code to determine if device detected
168	 * correctly.
169	 */
170	err = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_CHK_CODE_REG,
171				       buf, 4);
172	if (err)
173		return err;
174
175	tmp = get_unaligned_le32(buf);
176	if ((tmp & 0xffff0000) != ts_data->chip->ic_chkcode) {
177		dev_err(&client->dev, "%s ic mismatch, chkcode is %u\n",
178			__func__, tmp);
179		return -ENODEV;
180	}
181
182	usleep_range(10000, 11000);
183
184	/* Read firmware version and test if firmware missing. */
185	err = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_VERSION_REG,
186				       buf, 4);
187	if (err)
188		return err;
189
190	tmp = get_unaligned_le32(buf);
191	if (tmp == CST3XX_FIRMWARE_VER_INVALID_VAL) {
192		dev_err(&client->dev, "Device firmware missing\n");
193		return -ENODEV;
194	}
195
196	/*
197	 * Tests suggest cmd required to exit reading firmware regs.
198	 */
199	put_unaligned_le16(CST3XX_FIRMWARE_INFO_END_CMD, buf);
200	err = cst3xx_i2c_write(client, buf, 2);
201	if (err)
202		return err;
203
204	usleep_range(5000, 6000);
205
206	return 0;
207}
208
209static int cst3xx_bootloader_enter(struct i2c_client *client)
210{
211	int err;
212	u8 retry;
213	u32 tmp = 0;
214	unsigned char buf[3];
215
216	for (retry = 0; retry < 5; retry++) {
217		hyn_reset_proc(client, (7 + retry));
218		/* set cmd to enter program mode */
219		put_unaligned_le24(CST3XX_BOOTLDR_PROG_CMD, buf);
220		err = cst3xx_i2c_write(client, buf, 3);
221		if (err)
222			continue;
223
224		usleep_range(2000, 2500);
225
226		/* check whether in program mode */
227		err = cst3xx_i2c_read_register(client,
228					       CST3XX_BOOTLDR_PROG_CHK_REG,
229					       buf, 1);
230		if (err)
231			continue;
232
233		tmp = get_unaligned(buf);
234		if (tmp == CST3XX_BOOTLDR_CHK_VAL)
235			break;
236	}
237
238	if (tmp != CST3XX_BOOTLDR_CHK_VAL) {
239		dev_err(&client->dev, "%s unable to enter bootloader mode\n",
240			__func__);
241		return -ENODEV;
242	}
243
244	hyn_reset_proc(client, 40);
245
246	return 0;
247}
248
249static void cst3xx_report_contact(struct hynitron_ts_data *ts_data,
250				  u8 id, unsigned int x, unsigned int y, u8 w)
251{
252	input_mt_slot(ts_data->input_dev, id);
253	input_mt_report_slot_state(ts_data->input_dev, MT_TOOL_FINGER, 1);
254	touchscreen_report_pos(ts_data->input_dev, &ts_data->prop, x, y, true);
255	input_report_abs(ts_data->input_dev, ABS_MT_TOUCH_MAJOR, w);
256}
257
258static int cst3xx_finish_touch_read(struct i2c_client *client)
259{
260	unsigned char buf[3];
261	int err;
262
263	put_unaligned_le24(CST3XX_TOUCH_DATA_STOP_CMD, buf);
264	err = cst3xx_i2c_write(client, buf, 3);
265	if (err) {
266		dev_err(&client->dev,
267			"send read touch info ending failed: %d\n", err);
268		return err;
269	}
270
271	return 0;
272}
273
274/*
275 * Handle events from IRQ. Note that for cst3xx it appears that IRQ
276 * fires continuously while touched, otherwise once every 1500ms
277 * when not touched (assume touchscreen waking up periodically).
278 * Note buffer is sized for 5 fingers, if more needed buffer must
279 * be increased. The buffer contains 5 bytes for each touch point,
280 * a touch count byte, a check byte, and then a second check byte after
281 * all other touch points.
282 *
283 * For example 1 touch would look like this:
284 * touch1[5]:touch_count[1]:chk_byte[1]
285 *
286 * 3 touches would look like this:
287 * touch1[5]:touch_count[1]:chk_byte[1]:touch2[5]:touch3[5]:chk_byte[1]
288 */
289static void cst3xx_touch_report(struct i2c_client *client)
290{
291	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
292	u8 buf[28];
293	u8 finger_id, sw, w;
294	unsigned int x, y;
295	unsigned int touch_cnt, end_byte;
296	unsigned int idx = 0;
297	unsigned int i;
298	int err;
299
300	/* Read and validate the first bits of input data. */
301	err = cst3xx_i2c_read_register(client, CST3XX_TOUCH_DATA_PART_REG,
302				       buf, 28);
303	if (err ||
304	    buf[6] != CST3XX_TOUCH_DATA_CHK_VAL ||
305	    buf[0] == CST3XX_TOUCH_DATA_CHK_VAL) {
306		dev_err(&client->dev, "cst3xx touch read failure\n");
307		return;
308	}
309
310	/* Report to the device we're done reading the touch data. */
311	err = cst3xx_finish_touch_read(client);
312	if (err)
313		return;
314
315	touch_cnt = buf[5] & CST3XX_TOUCH_COUNT_MASK;
316	/*
317	 * Check the check bit of the last touch slot. The check bit is
318	 * always present after touch point 1 for valid data, and then
319	 * appears as the last byte after all other touch data.
320	 */
321	if (touch_cnt > 1) {
322		end_byte = touch_cnt * 5 + 2;
323		if (buf[end_byte] != CST3XX_TOUCH_DATA_CHK_VAL) {
324			dev_err(&client->dev, "cst3xx touch read failure\n");
325			return;
326		}
327	}
328
329	/* Parse through the buffer to capture touch data. */
330	for (i = 0; i < touch_cnt; i++) {
331		x = ((buf[idx + 1] << 4) | ((buf[idx + 3] >> 4) & 0x0f));
332		y = ((buf[idx + 2] << 4) | (buf[idx + 3] & 0x0f));
333		w = (buf[idx + 4] >> 3);
334		sw = (buf[idx] & 0x0f) >> 1;
335		finger_id = (buf[idx] >> 4) & 0x0f;
336
337		/* Sanity check we don't have more fingers than we expect */
338		if (ts_data->chip->max_touch_num < finger_id) {
339			dev_err(&client->dev, "cst3xx touch read failure\n");
340			break;
341		}
342
343		/* sw value of 0 means no touch, 0x03 means touch */
344		if (sw == CST3XX_TOUCH_DATA_TOUCH_VAL)
345			cst3xx_report_contact(ts_data, finger_id, x, y, w);
346
347		idx += 5;
348
349		/* Skip the 2 bytes between point 1 and point 2 */
350		if (i == 0)
351			idx += 2;
352	}
353
354	input_mt_sync_frame(ts_data->input_dev);
355	input_sync(ts_data->input_dev);
356}
357
358static int cst3xx_input_dev_int(struct i2c_client *client)
359{
360	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
361	int err;
362
363	ts_data->input_dev = devm_input_allocate_device(&client->dev);
364	if (!ts_data->input_dev) {
365		dev_err(&client->dev, "Failed to allocate input device\n");
366		return -ENOMEM;
367	}
368
369	ts_data->input_dev->name = "Hynitron cst3xx Touchscreen";
370	ts_data->input_dev->phys = "input/ts";
371	ts_data->input_dev->id.bustype = BUS_I2C;
372
373	input_set_drvdata(ts_data->input_dev, ts_data);
374
375	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_X);
376	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_Y);
377	input_set_abs_params(ts_data->input_dev, ABS_MT_TOUCH_MAJOR,
378			     0, 255, 0, 0);
379
380	touchscreen_parse_properties(ts_data->input_dev, true, &ts_data->prop);
381
382	if (!ts_data->prop.max_x || !ts_data->prop.max_y) {
383		dev_err(&client->dev,
384			"Invalid x/y (%d, %d), using defaults\n",
385			ts_data->prop.max_x, ts_data->prop.max_y);
386		ts_data->prop.max_x = 1152;
387		ts_data->prop.max_y = 1920;
388		input_abs_set_max(ts_data->input_dev,
389				  ABS_MT_POSITION_X, ts_data->prop.max_x);
390		input_abs_set_max(ts_data->input_dev,
391				  ABS_MT_POSITION_Y, ts_data->prop.max_y);
392	}
393
394	err = input_mt_init_slots(ts_data->input_dev,
395				  ts_data->chip->max_touch_num,
396				  INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
397	if (err) {
398		dev_err(&client->dev,
399			"Failed to initialize input slots: %d\n", err);
400		return err;
401	}
402
403	err = input_register_device(ts_data->input_dev);
404	if (err) {
405		dev_err(&client->dev,
406			"Input device registration failed: %d\n", err);
407		return err;
408	}
409
410	return 0;
411}
412
413static int hyn_probe(struct i2c_client *client)
414{
415	struct hynitron_ts_data *ts_data;
416	int err;
417
418	ts_data = devm_kzalloc(&client->dev, sizeof(*ts_data), GFP_KERNEL);
419	if (!ts_data)
420		return -ENOMEM;
421
422	ts_data->client = client;
423	i2c_set_clientdata(client, ts_data);
424
425	ts_data->chip = device_get_match_data(&client->dev);
426	if (!ts_data->chip)
427		return -EINVAL;
428
429	ts_data->reset_gpio = devm_gpiod_get(&client->dev,
430					     "reset", GPIOD_OUT_LOW);
431	err = PTR_ERR_OR_ZERO(ts_data->reset_gpio);
432	if (err) {
433		dev_err(&client->dev, "request reset gpio failed: %d\n", err);
434		return err;
435	}
436
437	hyn_reset_proc(client, 60);
438
439	err = ts_data->chip->bootloader_enter(client);
440	if (err < 0)
441		return err;
442
443	err = ts_data->chip->init_input(client);
444	if (err < 0)
445		return err;
446
447	err = ts_data->chip->firmware_info(client);
448	if (err < 0)
449		return err;
450
451	err = devm_request_threaded_irq(&client->dev, client->irq,
452					NULL, hyn_interrupt_handler,
453					IRQF_ONESHOT,
454					"Hynitron Touch Int", client);
455	if (err) {
456		dev_err(&client->dev, "failed to request IRQ: %d\n", err);
457		return err;
458	}
459
460	return 0;
461}
462
463static const struct hynitron_ts_chip_data cst3xx_data = {
464	.max_touch_num		= 5,
465	.ic_chkcode		= 0xcaca0000,
466	.firmware_info		= &cst3xx_firmware_info,
467	.bootloader_enter	= &cst3xx_bootloader_enter,
468	.init_input		= &cst3xx_input_dev_int,
469	.report_touch		= &cst3xx_touch_report,
470};
471
472static const struct i2c_device_id hyn_tpd_id[] = {
473	{ .name = "hynitron_ts", 0 },
474	{ /* sentinel */ },
475};
476MODULE_DEVICE_TABLE(i2c, hyn_tpd_id);
477
478static const struct of_device_id hyn_dt_match[] = {
479	{ .compatible = "hynitron,cst340", .data = &cst3xx_data },
480	{ /* sentinel */ },
481};
482MODULE_DEVICE_TABLE(of, hyn_dt_match);
483
484static struct i2c_driver hynitron_i2c_driver = {
485	.driver = {
486		.name = "Hynitron-TS",
487		.of_match_table = hyn_dt_match,
488		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
489	},
490	.id_table = hyn_tpd_id,
491	.probe = hyn_probe,
492};
493
494module_i2c_driver(hynitron_i2c_driver);
495
496MODULE_AUTHOR("Chris Morgan");
497MODULE_DESCRIPTION("Hynitron Touchscreen Driver");
498MODULE_LICENSE("GPL");
499