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/module.h>
23 #include <linux/property.h>
24 #include <linux/unaligned.h>
25
26 /* Per chip data */
27 struct hynitron_ts_chip_data {
28 unsigned int max_touch_num;
29 u32 ic_chkcode;
30 int (*firmware_info)(struct i2c_client *client);
31 int (*bootloader_enter)(struct i2c_client *client);
32 int (*init_input)(struct i2c_client *client);
33 void (*report_touch)(struct i2c_client *client);
34 };
35
36 /* Data generic to all (supported and non-supported) controllers. */
37 struct hynitron_ts_data {
38 const struct hynitron_ts_chip_data *chip;
39 struct i2c_client *client;
40 struct input_dev *input_dev;
41 struct touchscreen_properties prop;
42 struct gpio_desc *reset_gpio;
43 };
44
45 /*
46 * Since I have no datasheet, these values are guessed and/or assumed
47 * based on observation and testing.
48 */
49 #define CST3XX_FIRMWARE_INFO_START_CMD 0x01d1
50 #define CST3XX_FIRMWARE_INFO_END_CMD 0x09d1
51 #define CST3XX_FIRMWARE_CHK_CODE_REG 0xfcd1
52 #define CST3XX_FIRMWARE_VERSION_REG 0x08d2
53 #define CST3XX_FIRMWARE_VER_INVALID_VAL 0xa5a5a5a5
54
55 #define CST3XX_BOOTLDR_PROG_CMD 0xaa01a0
56 #define CST3XX_BOOTLDR_PROG_CHK_REG 0x02a0
57 #define CST3XX_BOOTLDR_CHK_VAL 0xac
58
59 #define CST3XX_TOUCH_DATA_PART_REG 0x00d0
60 #define CST3XX_TOUCH_DATA_FULL_REG 0x07d0
61 #define CST3XX_TOUCH_DATA_CHK_VAL 0xab
62 #define CST3XX_TOUCH_DATA_TOUCH_VAL 0x03
63 #define CST3XX_TOUCH_DATA_STOP_CMD 0xab00d0
64 #define CST3XX_TOUCH_COUNT_MASK GENMASK(6, 0)
65
66
67 /*
68 * Hard coded reset delay value of 20ms not IC dependent in
69 * vendor driver.
70 */
hyn_reset_proc(struct i2c_client * client,int delay)71 static void hyn_reset_proc(struct i2c_client *client, int delay)
72 {
73 struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
74
75 gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
76 msleep(20);
77 gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
78 if (delay)
79 fsleep(delay * 1000);
80 }
81
hyn_interrupt_handler(int irq,void * dev_id)82 static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
83 {
84 struct i2c_client *client = dev_id;
85 struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
86
87 ts_data->chip->report_touch(client);
88
89 return IRQ_HANDLED;
90 }
91
92 /*
93 * The vendor driver would retry twice before failing to read or write
94 * to the i2c device.
95 */
96
cst3xx_i2c_write(struct i2c_client * client,unsigned char * buf,int len)97 static int cst3xx_i2c_write(struct i2c_client *client,
98 unsigned char *buf, int len)
99 {
100 int ret;
101 int retries = 0;
102
103 while (retries < 2) {
104 ret = i2c_master_send(client, buf, len);
105 if (ret == len)
106 return 0;
107 if (ret <= 0)
108 retries++;
109 else
110 break;
111 }
112
113 return ret < 0 ? ret : -EIO;
114 }
115
cst3xx_i2c_read_register(struct i2c_client * client,u16 reg,u8 * val,u16 len)116 static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
117 u8 *val, u16 len)
118 {
119 __le16 buf = cpu_to_le16(reg);
120 struct i2c_msg msgs[] = {
121 {
122 .addr = client->addr,
123 .flags = 0,
124 .len = 2,
125 .buf = (u8 *)&buf,
126 },
127 {
128 .addr = client->addr,
129 .flags = I2C_M_RD,
130 .len = len,
131 .buf = val,
132 }
133 };
134 int err;
135 int ret;
136
137 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
138 if (ret == ARRAY_SIZE(msgs))
139 return 0;
140
141 err = ret < 0 ? ret : -EIO;
142 dev_err(&client->dev, "Error reading %d bytes from 0x%04x: %d (%d)\n",
143 len, reg, err, ret);
144
145 return err;
146 }
147
cst3xx_firmware_info(struct i2c_client * client)148 static int cst3xx_firmware_info(struct i2c_client *client)
149 {
150 struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
151 int err;
152 u32 tmp;
153 unsigned char buf[4];
154
155 /*
156 * Tests suggest this command needed to read firmware regs.
157 */
158 put_unaligned_le16(CST3XX_FIRMWARE_INFO_START_CMD, buf);
159 err = cst3xx_i2c_write(client, buf, 2);
160 if (err)
161 return err;
162
163 usleep_range(10000, 11000);
164
165 /*
166 * Read register for check-code to determine if device detected
167 * correctly.
168 */
169 err = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_CHK_CODE_REG,
170 buf, 4);
171 if (err)
172 return err;
173
174 tmp = get_unaligned_le32(buf);
175 if ((tmp & 0xffff0000) != ts_data->chip->ic_chkcode) {
176 dev_err(&client->dev, "%s ic mismatch, chkcode is %u\n",
177 __func__, tmp);
178 return -ENODEV;
179 }
180
181 usleep_range(10000, 11000);
182
183 /* Read firmware version and test if firmware missing. */
184 err = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_VERSION_REG,
185 buf, 4);
186 if (err)
187 return err;
188
189 tmp = get_unaligned_le32(buf);
190 if (tmp == CST3XX_FIRMWARE_VER_INVALID_VAL) {
191 dev_err(&client->dev, "Device firmware missing\n");
192 return -ENODEV;
193 }
194
195 /*
196 * Tests suggest cmd required to exit reading firmware regs.
197 */
198 put_unaligned_le16(CST3XX_FIRMWARE_INFO_END_CMD, buf);
199 err = cst3xx_i2c_write(client, buf, 2);
200 if (err)
201 return err;
202
203 usleep_range(5000, 6000);
204
205 return 0;
206 }
207
cst3xx_bootloader_enter(struct i2c_client * client)208 static int cst3xx_bootloader_enter(struct i2c_client *client)
209 {
210 int err;
211 u8 retry;
212 u32 tmp = 0;
213 unsigned char buf[3];
214
215 for (retry = 0; retry < 5; retry++) {
216 hyn_reset_proc(client, (7 + retry));
217 /* set cmd to enter program mode */
218 put_unaligned_le24(CST3XX_BOOTLDR_PROG_CMD, buf);
219 err = cst3xx_i2c_write(client, buf, 3);
220 if (err)
221 continue;
222
223 usleep_range(2000, 2500);
224
225 /* check whether in program mode */
226 err = cst3xx_i2c_read_register(client,
227 CST3XX_BOOTLDR_PROG_CHK_REG,
228 buf, 1);
229 if (err)
230 continue;
231
232 tmp = get_unaligned(buf);
233 if (tmp == CST3XX_BOOTLDR_CHK_VAL)
234 break;
235 }
236
237 if (tmp != CST3XX_BOOTLDR_CHK_VAL) {
238 dev_err(&client->dev, "%s unable to enter bootloader mode\n",
239 __func__);
240 return -ENODEV;
241 }
242
243 hyn_reset_proc(client, 40);
244
245 return 0;
246 }
247
cst3xx_report_contact(struct hynitron_ts_data * ts_data,u8 id,unsigned int x,unsigned int y,u8 w)248 static void cst3xx_report_contact(struct hynitron_ts_data *ts_data,
249 u8 id, unsigned int x, unsigned int y, u8 w)
250 {
251 input_mt_slot(ts_data->input_dev, id);
252 input_mt_report_slot_state(ts_data->input_dev, MT_TOOL_FINGER, 1);
253 touchscreen_report_pos(ts_data->input_dev, &ts_data->prop, x, y, true);
254 input_report_abs(ts_data->input_dev, ABS_MT_TOUCH_MAJOR, w);
255 }
256
cst3xx_finish_touch_read(struct i2c_client * client)257 static int cst3xx_finish_touch_read(struct i2c_client *client)
258 {
259 unsigned char buf[3];
260 int err;
261
262 put_unaligned_le24(CST3XX_TOUCH_DATA_STOP_CMD, buf);
263 err = cst3xx_i2c_write(client, buf, 3);
264 if (err) {
265 dev_err(&client->dev,
266 "send read touch info ending failed: %d\n", err);
267 return err;
268 }
269
270 return 0;
271 }
272
273 /*
274 * Handle events from IRQ. Note that for cst3xx it appears that IRQ
275 * fires continuously while touched, otherwise once every 1500ms
276 * when not touched (assume touchscreen waking up periodically).
277 * Note buffer is sized for 5 fingers, if more needed buffer must
278 * be increased. The buffer contains 5 bytes for each touch point,
279 * a touch count byte, a check byte, and then a second check byte after
280 * all other touch points.
281 *
282 * For example 1 touch would look like this:
283 * touch1[5]:touch_count[1]:chk_byte[1]
284 *
285 * 3 touches would look like this:
286 * touch1[5]:touch_count[1]:chk_byte[1]:touch2[5]:touch3[5]:chk_byte[1]
287 */
cst3xx_touch_report(struct i2c_client * client)288 static void cst3xx_touch_report(struct i2c_client *client)
289 {
290 struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
291 u8 buf[28];
292 u8 finger_id, sw, w;
293 unsigned int x, y;
294 unsigned int touch_cnt, end_byte;
295 unsigned int idx = 0;
296 unsigned int i;
297 int err;
298
299 /* Read and validate the first bits of input data. */
300 err = cst3xx_i2c_read_register(client, CST3XX_TOUCH_DATA_PART_REG,
301 buf, 28);
302 if (err ||
303 buf[6] != CST3XX_TOUCH_DATA_CHK_VAL ||
304 buf[0] == CST3XX_TOUCH_DATA_CHK_VAL) {
305 dev_err(&client->dev, "cst3xx touch read failure\n");
306 return;
307 }
308
309 /* Report to the device we're done reading the touch data. */
310 err = cst3xx_finish_touch_read(client);
311 if (err)
312 return;
313
314 touch_cnt = buf[5] & CST3XX_TOUCH_COUNT_MASK;
315 if (touch_cnt > ts_data->chip->max_touch_num) {
316 dev_err(&client->dev, "cst3xx invalid touch count (%d vs %d max)\n",
317 touch_cnt, ts_data->chip->max_touch_num);
318 return;
319 }
320
321 /*
322 * Check the check bit of the last touch slot. The check bit is
323 * always present after touch point 1 for valid data, and then
324 * appears as the last byte after all other touch data.
325 */
326 if (touch_cnt > 1) {
327 end_byte = touch_cnt * 5 + 2;
328 if (buf[end_byte] != CST3XX_TOUCH_DATA_CHK_VAL) {
329 dev_err(&client->dev, "cst3xx touch read failure\n");
330 return;
331 }
332 }
333
334 /* Parse through the buffer to capture touch data. */
335 for (i = 0; i < touch_cnt; i++) {
336 x = ((buf[idx + 1] << 4) | ((buf[idx + 3] >> 4) & 0x0f));
337 y = ((buf[idx + 2] << 4) | (buf[idx + 3] & 0x0f));
338 w = (buf[idx + 4] >> 3);
339 sw = (buf[idx] & 0x0f) >> 1;
340 finger_id = (buf[idx] >> 4) & 0x0f;
341
342 /* Sanity check we don't have more fingers than we expect */
343 if (finger_id >= ts_data->chip->max_touch_num) {
344 dev_err(&client->dev,
345 "cst3xx invalid finger id %d\n", finger_id);
346 return;
347 }
348
349 /* sw value of 0 means no touch, 0x03 means touch */
350 if (sw == CST3XX_TOUCH_DATA_TOUCH_VAL)
351 cst3xx_report_contact(ts_data, finger_id, x, y, w);
352
353 idx += 5;
354
355 /* Skip the 2 bytes between point 1 and point 2 */
356 if (i == 0)
357 idx += 2;
358 }
359
360 input_mt_sync_frame(ts_data->input_dev);
361 input_sync(ts_data->input_dev);
362 }
363
cst3xx_input_dev_int(struct i2c_client * client)364 static int cst3xx_input_dev_int(struct i2c_client *client)
365 {
366 struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
367 int err;
368
369 ts_data->input_dev = devm_input_allocate_device(&client->dev);
370 if (!ts_data->input_dev) {
371 dev_err(&client->dev, "Failed to allocate input device\n");
372 return -ENOMEM;
373 }
374
375 ts_data->input_dev->name = "Hynitron cst3xx Touchscreen";
376 ts_data->input_dev->phys = "input/ts";
377 ts_data->input_dev->id.bustype = BUS_I2C;
378
379 input_set_drvdata(ts_data->input_dev, ts_data);
380
381 input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_X);
382 input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_Y);
383 input_set_abs_params(ts_data->input_dev, ABS_MT_TOUCH_MAJOR,
384 0, 255, 0, 0);
385
386 touchscreen_parse_properties(ts_data->input_dev, true, &ts_data->prop);
387
388 if (!ts_data->prop.max_x || !ts_data->prop.max_y) {
389 dev_err(&client->dev,
390 "Invalid x/y (%d, %d), using defaults\n",
391 ts_data->prop.max_x, ts_data->prop.max_y);
392 ts_data->prop.max_x = 1152;
393 ts_data->prop.max_y = 1920;
394 input_abs_set_max(ts_data->input_dev,
395 ABS_MT_POSITION_X, ts_data->prop.max_x);
396 input_abs_set_max(ts_data->input_dev,
397 ABS_MT_POSITION_Y, ts_data->prop.max_y);
398 }
399
400 err = input_mt_init_slots(ts_data->input_dev,
401 ts_data->chip->max_touch_num,
402 INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
403 if (err) {
404 dev_err(&client->dev,
405 "Failed to initialize input slots: %d\n", err);
406 return err;
407 }
408
409 err = input_register_device(ts_data->input_dev);
410 if (err) {
411 dev_err(&client->dev,
412 "Input device registration failed: %d\n", err);
413 return err;
414 }
415
416 return 0;
417 }
418
hyn_probe(struct i2c_client * client)419 static int hyn_probe(struct i2c_client *client)
420 {
421 struct hynitron_ts_data *ts_data;
422 int err;
423
424 ts_data = devm_kzalloc(&client->dev, sizeof(*ts_data), GFP_KERNEL);
425 if (!ts_data)
426 return -ENOMEM;
427
428 ts_data->client = client;
429 i2c_set_clientdata(client, ts_data);
430
431 ts_data->chip = device_get_match_data(&client->dev);
432 if (!ts_data->chip)
433 return -EINVAL;
434
435 ts_data->reset_gpio = devm_gpiod_get(&client->dev,
436 "reset", GPIOD_OUT_LOW);
437 err = PTR_ERR_OR_ZERO(ts_data->reset_gpio);
438 if (err) {
439 dev_err(&client->dev, "request reset gpio failed: %d\n", err);
440 return err;
441 }
442
443 hyn_reset_proc(client, 60);
444
445 err = ts_data->chip->bootloader_enter(client);
446 if (err < 0)
447 return err;
448
449 err = ts_data->chip->init_input(client);
450 if (err < 0)
451 return err;
452
453 err = ts_data->chip->firmware_info(client);
454 if (err < 0)
455 return err;
456
457 err = devm_request_threaded_irq(&client->dev, client->irq,
458 NULL, hyn_interrupt_handler,
459 IRQF_ONESHOT,
460 "Hynitron Touch Int", client);
461 if (err) {
462 dev_err(&client->dev, "failed to request IRQ: %d\n", err);
463 return err;
464 }
465
466 return 0;
467 }
468
469 static const struct hynitron_ts_chip_data cst3xx_data = {
470 .max_touch_num = 5,
471 .ic_chkcode = 0xcaca0000,
472 .firmware_info = &cst3xx_firmware_info,
473 .bootloader_enter = &cst3xx_bootloader_enter,
474 .init_input = &cst3xx_input_dev_int,
475 .report_touch = &cst3xx_touch_report,
476 };
477
478 static const struct i2c_device_id hyn_tpd_id[] = {
479 { .name = "hynitron_ts" },
480 { /* sentinel */ },
481 };
482 MODULE_DEVICE_TABLE(i2c, hyn_tpd_id);
483
484 static const struct of_device_id hyn_dt_match[] = {
485 { .compatible = "hynitron,cst340", .data = &cst3xx_data },
486 { /* sentinel */ },
487 };
488 MODULE_DEVICE_TABLE(of, hyn_dt_match);
489
490 static struct i2c_driver hynitron_i2c_driver = {
491 .driver = {
492 .name = "Hynitron-TS",
493 .of_match_table = hyn_dt_match,
494 .probe_type = PROBE_PREFER_ASYNCHRONOUS,
495 },
496 .id_table = hyn_tpd_id,
497 .probe = hyn_probe,
498 };
499
500 module_i2c_driver(hynitron_i2c_driver);
501
502 MODULE_AUTHOR("Chris Morgan");
503 MODULE_DESCRIPTION("Hynitron Touchscreen Driver");
504 MODULE_LICENSE("GPL");
505