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 <linux/unaligned.h>
26
27 /* Per chip data */
28 struct 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. */
38 struct 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 */
hyn_reset_proc(struct i2c_client * client,int delay)72 static 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
hyn_interrupt_handler(int irq,void * dev_id)83 static 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
cst3xx_i2c_write(struct i2c_client * client,unsigned char * buf,int len)98 static 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
cst3xx_i2c_read_register(struct i2c_client * client,u16 reg,u8 * val,u16 len)117 static 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
cst3xx_firmware_info(struct i2c_client * client)149 static 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
cst3xx_bootloader_enter(struct i2c_client * client)209 static 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
cst3xx_report_contact(struct hynitron_ts_data * ts_data,u8 id,unsigned int x,unsigned int y,u8 w)249 static 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
cst3xx_finish_touch_read(struct i2c_client * client)258 static 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 */
cst3xx_touch_report(struct i2c_client * client)289 static 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
cst3xx_input_dev_int(struct i2c_client * client)358 static 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
hyn_probe(struct i2c_client * client)413 static 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
463 static 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
472 static const struct i2c_device_id hyn_tpd_id[] = {
473 { .name = "hynitron_ts" },
474 { /* sentinel */ },
475 };
476 MODULE_DEVICE_TABLE(i2c, hyn_tpd_id);
477
478 static const struct of_device_id hyn_dt_match[] = {
479 { .compatible = "hynitron,cst340", .data = &cst3xx_data },
480 { /* sentinel */ },
481 };
482 MODULE_DEVICE_TABLE(of, hyn_dt_match);
483
484 static 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
494 module_i2c_driver(hynitron_i2c_driver);
495
496 MODULE_AUTHOR("Chris Morgan");
497 MODULE_DESCRIPTION("Hynitron Touchscreen Driver");
498 MODULE_LICENSE("GPL");
499