1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Rohm BU21029 touchscreen controller driver
4 *
5 * Copyright (C) 2015-2018 Bosch Sicherheitssysteme GmbH
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12 #include <linux/delay.h>
13 #include <linux/gpio/consumer.h>
14 #include <linux/i2c.h>
15 #include <linux/input.h>
16 #include <linux/input/touchscreen.h>
17 #include <linux/interrupt.h>
18 #include <linux/irq.h>
19 #include <linux/module.h>
20 #include <linux/regulator/consumer.h>
21 #include <linux/timer.h>
22
23 /*
24 * HW_ID1 Register (PAGE=0, ADDR=0x0E, Reset value=0x02, Read only)
25 * +--------+--------+--------+--------+--------+--------+--------+--------+
26 * | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
27 * +--------+--------+--------+--------+--------+--------+--------+--------+
28 * | HW_IDH |
29 * +--------+--------+--------+--------+--------+--------+--------+--------+
30 * HW_ID2 Register (PAGE=0, ADDR=0x0F, Reset value=0x29, Read only)
31 * +--------+--------+--------+--------+--------+--------+--------+--------+
32 * | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
33 * +--------+--------+--------+--------+--------+--------+--------+--------+
34 * | HW_IDL |
35 * +--------+--------+--------+--------+--------+--------+--------+--------+
36 * HW_IDH: high 8bits of IC's ID
37 * HW_IDL: low 8bits of IC's ID
38 */
39 #define BU21029_HWID_REG (0x0E << 3)
40 #define SUPPORTED_HWID 0x0229
41
42 /*
43 * CFR0 Register (PAGE=0, ADDR=0x00, Reset value=0x20)
44 * +--------+--------+--------+--------+--------+--------+--------+--------+
45 * | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
46 * +--------+--------+--------+--------+--------+--------+--------+--------+
47 * | 0 | 0 | CALIB | INTRM | 0 | 0 | 0 | 0 |
48 * +--------+--------+--------+--------+--------+--------+--------+--------+
49 * CALIB: 0 = not to use calibration result (*)
50 * 1 = use calibration result
51 * INTRM: 0 = INT output depend on "pen down" (*)
52 * 1 = INT output always "0"
53 */
54 #define BU21029_CFR0_REG (0x00 << 3)
55 #define CFR0_VALUE 0x00
56
57 /*
58 * CFR1 Register (PAGE=0, ADDR=0x01, Reset value=0xA6)
59 * +--------+--------+--------+--------+--------+--------+--------+--------+
60 * | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
61 * +--------+--------+--------+--------+--------+--------+--------+--------+
62 * | MAV | AVE[2:0] | 0 | SMPL[2:0] |
63 * +--------+--------+--------+--------+--------+--------+--------+--------+
64 * MAV: 0 = median average filter off
65 * 1 = median average filter on (*)
66 * AVE: AVE+1 = number of average samples for MAV,
67 * if AVE>SMPL, then AVE=SMPL (=3)
68 * SMPL: SMPL+1 = number of conversion samples for MAV (=7)
69 */
70 #define BU21029_CFR1_REG (0x01 << 3)
71 #define CFR1_VALUE 0xA6
72
73 /*
74 * CFR2 Register (PAGE=0, ADDR=0x02, Reset value=0x04)
75 * +--------+--------+--------+--------+--------+--------+--------+--------+
76 * | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
77 * +--------+--------+--------+--------+--------+--------+--------+--------+
78 * | INTVL_TIME[3:0] | TIME_ST_ADC[3:0] |
79 * +--------+--------+--------+--------+--------+--------+--------+--------+
80 * INTVL_TIME: waiting time between completion of conversion
81 * and start of next conversion, only usable in
82 * autoscan mode (=20.480ms)
83 * TIME_ST_ADC: waiting time between application of voltage
84 * to panel and start of A/D conversion (=100us)
85 */
86 #define BU21029_CFR2_REG (0x02 << 3)
87 #define CFR2_VALUE 0xC9
88
89 /*
90 * CFR3 Register (PAGE=0, ADDR=0x0B, Reset value=0x72)
91 * +--------+--------+--------+--------+--------+--------+--------+--------+
92 * | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
93 * +--------+--------+--------+--------+--------+--------+--------+--------+
94 * | RM8 | STRETCH| PU90K | DUAL | PIDAC_OFS[3:0] |
95 * +--------+--------+--------+--------+--------+--------+--------+--------+
96 * RM8: 0 = coordinate resolution is 12bit (*)
97 * 1 = coordinate resolution is 8bit
98 * STRETCH: 0 = SCL_STRETCH function off
99 * 1 = SCL_STRETCH function on (*)
100 * PU90K: 0 = internal pull-up resistance for touch detection is ~50kohms (*)
101 * 1 = internal pull-up resistance for touch detection is ~90kohms
102 * DUAL: 0 = dual touch detection off (*)
103 * 1 = dual touch detection on
104 * PIDAC_OFS: dual touch detection circuit adjustment, it is not necessary
105 * to change this from initial value
106 */
107 #define BU21029_CFR3_REG (0x0B << 3)
108 #define CFR3_VALUE 0x42
109
110 /*
111 * LDO Register (PAGE=0, ADDR=0x0C, Reset value=0x00)
112 * +--------+--------+--------+--------+--------+--------+--------+--------+
113 * | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
114 * +--------+--------+--------+--------+--------+--------+--------+--------+
115 * | 0 | PVDD[2:0] | 0 | AVDD[2:0] |
116 * +--------+--------+--------+--------+--------+--------+--------+--------+
117 * PVDD: output voltage of panel output regulator (=2.000V)
118 * AVDD: output voltage of analog circuit regulator (=2.000V)
119 */
120 #define BU21029_LDO_REG (0x0C << 3)
121 #define LDO_VALUE 0x77
122
123 /*
124 * Serial Interface Command Byte 1 (CID=1)
125 * +--------+--------+--------+--------+--------+--------+--------+--------+
126 * | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
127 * +--------+--------+--------+--------+--------+--------+--------+--------+
128 * | 1 | CF | CMSK | PDM | STP |
129 * +--------+--------+--------+--------+--------+--------+--------+--------+
130 * CF: conversion function, see table 3 in datasheet p6 (=0000, automatic scan)
131 * CMSK: 0 = executes convert function (*)
132 * 1 = reads the convert result
133 * PDM: 0 = power down after convert function stops (*)
134 * 1 = keep power on after convert function stops
135 * STP: 1 = abort current conversion and power down, set to "0" automatically
136 */
137 #define BU21029_AUTOSCAN 0x80
138
139 /*
140 * The timeout value needs to be larger than INTVL_TIME + tConv4 (sample and
141 * conversion time), where tConv4 is calculated by formula:
142 * tPON + tDLY1 + (tTIME_ST_ADC + (tADC * tSMPL) * 2 + tDLY2) * 3
143 * see figure 8 in datasheet p15 for details of each field.
144 */
145 #define PEN_UP_TIMEOUT_MS 50
146
147 #define STOP_DELAY_MIN_US 50
148 #define STOP_DELAY_MAX_US 1000
149 #define START_DELAY_MS 2
150 #define BUF_LEN 8
151 #define SCALE_12BIT (1 << 12)
152 #define MAX_12BIT ((1 << 12) - 1)
153 #define DRIVER_NAME "bu21029"
154
155 struct bu21029_ts_data {
156 struct i2c_client *client;
157 struct input_dev *in_dev;
158 struct timer_list timer;
159 struct regulator *vdd;
160 struct gpio_desc *reset_gpios;
161 u32 x_plate_ohms;
162 struct touchscreen_properties prop;
163 };
164
bu21029_touch_report(struct bu21029_ts_data * bu21029,const u8 * buf)165 static void bu21029_touch_report(struct bu21029_ts_data *bu21029, const u8 *buf)
166 {
167 u16 x, y, z1, z2;
168 u32 rz;
169 s32 max_pressure = input_abs_get_max(bu21029->in_dev, ABS_PRESSURE);
170
171 /*
172 * compose upper 8 and lower 4 bits into a 12bit value:
173 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
174 * | ByteH | ByteL |
175 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
176 * |b07|b06|b05|b04|b03|b02|b01|b00|b07|b06|b05|b04|b03|b02|b01|b00|
177 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
178 * |v11|v10|v09|v08|v07|v06|v05|v04|v03|v02|v01|v00| 0 | 0 | 0 | 0 |
179 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
180 */
181 x = (buf[0] << 4) | (buf[1] >> 4);
182 y = (buf[2] << 4) | (buf[3] >> 4);
183 z1 = (buf[4] << 4) | (buf[5] >> 4);
184 z2 = (buf[6] << 4) | (buf[7] >> 4);
185
186 if (z1 && z2) {
187 /*
188 * calculate Rz (pressure resistance value) by equation:
189 * Rz = Rx * (x/Q) * ((z2/z1) - 1), where
190 * Rx is x-plate resistance,
191 * Q is the touch screen resolution (8bit = 256, 12bit = 4096)
192 * x, z1, z2 are the measured positions.
193 */
194 rz = z2 - z1;
195 rz *= x;
196 rz *= bu21029->x_plate_ohms;
197 rz /= z1;
198 rz = DIV_ROUND_CLOSEST(rz, SCALE_12BIT);
199 if (rz <= max_pressure) {
200 touchscreen_report_pos(bu21029->in_dev, &bu21029->prop,
201 x, y, false);
202 input_report_abs(bu21029->in_dev, ABS_PRESSURE,
203 max_pressure - rz);
204 input_report_key(bu21029->in_dev, BTN_TOUCH, 1);
205 input_sync(bu21029->in_dev);
206 }
207 }
208 }
209
bu21029_touch_release(struct timer_list * t)210 static void bu21029_touch_release(struct timer_list *t)
211 {
212 struct bu21029_ts_data *bu21029 = timer_container_of(bu21029, t,
213 timer);
214
215 input_report_abs(bu21029->in_dev, ABS_PRESSURE, 0);
216 input_report_key(bu21029->in_dev, BTN_TOUCH, 0);
217 input_sync(bu21029->in_dev);
218 }
219
bu21029_touch_soft_irq(int irq,void * data)220 static irqreturn_t bu21029_touch_soft_irq(int irq, void *data)
221 {
222 struct bu21029_ts_data *bu21029 = data;
223 u8 buf[BUF_LEN];
224 int error;
225
226 /*
227 * Read touch data and deassert interrupt (will assert again after
228 * INTVL_TIME + tConv4 for continuous touch)
229 */
230 error = i2c_smbus_read_i2c_block_data(bu21029->client, BU21029_AUTOSCAN,
231 sizeof(buf), buf);
232 if (error < 0)
233 goto out;
234
235 bu21029_touch_report(bu21029, buf);
236
237 /* reset timer for pen up detection */
238 mod_timer(&bu21029->timer,
239 jiffies + msecs_to_jiffies(PEN_UP_TIMEOUT_MS));
240
241 out:
242 return IRQ_HANDLED;
243 }
244
bu21029_put_chip_in_reset(struct bu21029_ts_data * bu21029)245 static void bu21029_put_chip_in_reset(struct bu21029_ts_data *bu21029)
246 {
247 if (bu21029->reset_gpios) {
248 gpiod_set_value_cansleep(bu21029->reset_gpios, 1);
249 usleep_range(STOP_DELAY_MIN_US, STOP_DELAY_MAX_US);
250 }
251 }
252
bu21029_start_chip(struct input_dev * dev)253 static int bu21029_start_chip(struct input_dev *dev)
254 {
255 struct bu21029_ts_data *bu21029 = input_get_drvdata(dev);
256 struct i2c_client *i2c = bu21029->client;
257 struct {
258 u8 reg;
259 u8 value;
260 } init_table[] = {
261 {BU21029_CFR0_REG, CFR0_VALUE},
262 {BU21029_CFR1_REG, CFR1_VALUE},
263 {BU21029_CFR2_REG, CFR2_VALUE},
264 {BU21029_CFR3_REG, CFR3_VALUE},
265 {BU21029_LDO_REG, LDO_VALUE}
266 };
267 int error, i;
268 __be16 hwid;
269
270 error = regulator_enable(bu21029->vdd);
271 if (error) {
272 dev_err(&i2c->dev, "failed to power up chip: %d", error);
273 return error;
274 }
275
276 /* take chip out of reset */
277 if (bu21029->reset_gpios) {
278 gpiod_set_value_cansleep(bu21029->reset_gpios, 0);
279 msleep(START_DELAY_MS);
280 }
281
282 error = i2c_smbus_read_i2c_block_data(i2c, BU21029_HWID_REG,
283 sizeof(hwid), (u8 *)&hwid);
284 if (error < 0) {
285 dev_err(&i2c->dev, "failed to read HW ID\n");
286 goto err_out;
287 }
288
289 if (be16_to_cpu(hwid) != SUPPORTED_HWID) {
290 dev_err(&i2c->dev,
291 "unsupported HW ID 0x%x\n", be16_to_cpu(hwid));
292 error = -ENODEV;
293 goto err_out;
294 }
295
296 for (i = 0; i < ARRAY_SIZE(init_table); ++i) {
297 error = i2c_smbus_write_byte_data(i2c,
298 init_table[i].reg,
299 init_table[i].value);
300 if (error < 0) {
301 dev_err(&i2c->dev,
302 "failed to write %#02x to register %#02x: %d\n",
303 init_table[i].value, init_table[i].reg,
304 error);
305 goto err_out;
306 }
307 }
308
309 error = i2c_smbus_write_byte(i2c, BU21029_AUTOSCAN);
310 if (error < 0) {
311 dev_err(&i2c->dev, "failed to start autoscan\n");
312 goto err_out;
313 }
314
315 enable_irq(bu21029->client->irq);
316 return 0;
317
318 err_out:
319 bu21029_put_chip_in_reset(bu21029);
320 regulator_disable(bu21029->vdd);
321 return error;
322 }
323
bu21029_stop_chip(struct input_dev * dev)324 static void bu21029_stop_chip(struct input_dev *dev)
325 {
326 struct bu21029_ts_data *bu21029 = input_get_drvdata(dev);
327
328 disable_irq(bu21029->client->irq);
329 timer_delete_sync(&bu21029->timer);
330
331 bu21029_put_chip_in_reset(bu21029);
332 regulator_disable(bu21029->vdd);
333 }
334
bu21029_probe(struct i2c_client * client)335 static int bu21029_probe(struct i2c_client *client)
336 {
337 struct device *dev = &client->dev;
338 struct bu21029_ts_data *bu21029;
339 struct input_dev *in_dev;
340 int error;
341
342 if (!i2c_check_functionality(client->adapter,
343 I2C_FUNC_SMBUS_WRITE_BYTE |
344 I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
345 I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
346 dev_err(dev, "i2c functionality support is not sufficient\n");
347 return -EIO;
348 }
349
350 bu21029 = devm_kzalloc(dev, sizeof(*bu21029), GFP_KERNEL);
351 if (!bu21029)
352 return -ENOMEM;
353
354 error = device_property_read_u32(dev, "rohm,x-plate-ohms", &bu21029->x_plate_ohms);
355 if (error) {
356 dev_err(dev, "invalid 'x-plate-ohms' supplied: %d\n", error);
357 return error;
358 }
359
360 bu21029->vdd = devm_regulator_get(dev, "vdd");
361 if (IS_ERR(bu21029->vdd))
362 return dev_err_probe(dev, PTR_ERR(bu21029->vdd),
363 "failed to acquire 'vdd' supply\n");
364
365 bu21029->reset_gpios = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
366 if (IS_ERR(bu21029->reset_gpios))
367 return dev_err_probe(dev, PTR_ERR(bu21029->reset_gpios),
368 "failed to acquire 'reset' gpio\n");
369
370 in_dev = devm_input_allocate_device(dev);
371 if (!in_dev) {
372 dev_err(dev, "unable to allocate input device\n");
373 return -ENOMEM;
374 }
375
376 bu21029->client = client;
377 bu21029->in_dev = in_dev;
378 timer_setup(&bu21029->timer, bu21029_touch_release, 0);
379
380 in_dev->name = DRIVER_NAME;
381 in_dev->id.bustype = BUS_I2C;
382 in_dev->open = bu21029_start_chip;
383 in_dev->close = bu21029_stop_chip;
384
385 input_set_capability(in_dev, EV_KEY, BTN_TOUCH);
386 input_set_abs_params(in_dev, ABS_X, 0, MAX_12BIT, 0, 0);
387 input_set_abs_params(in_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
388 input_set_abs_params(in_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);
389 touchscreen_parse_properties(in_dev, false, &bu21029->prop);
390
391 input_set_drvdata(in_dev, bu21029);
392
393 error = devm_request_threaded_irq(dev, client->irq, NULL,
394 bu21029_touch_soft_irq,
395 IRQF_ONESHOT | IRQF_NO_AUTOEN,
396 DRIVER_NAME, bu21029);
397 if (error) {
398 dev_err(dev, "unable to request touch irq: %d\n", error);
399 return error;
400 }
401
402 error = input_register_device(in_dev);
403 if (error) {
404 dev_err(dev, "unable to register input device: %d\n", error);
405 return error;
406 }
407
408 i2c_set_clientdata(client, bu21029);
409
410 return 0;
411 }
412
bu21029_suspend(struct device * dev)413 static int bu21029_suspend(struct device *dev)
414 {
415 struct i2c_client *i2c = to_i2c_client(dev);
416 struct bu21029_ts_data *bu21029 = i2c_get_clientdata(i2c);
417
418 if (!device_may_wakeup(dev)) {
419 mutex_lock(&bu21029->in_dev->mutex);
420 if (input_device_enabled(bu21029->in_dev))
421 bu21029_stop_chip(bu21029->in_dev);
422 mutex_unlock(&bu21029->in_dev->mutex);
423 }
424
425 return 0;
426 }
427
bu21029_resume(struct device * dev)428 static int bu21029_resume(struct device *dev)
429 {
430 struct i2c_client *i2c = to_i2c_client(dev);
431 struct bu21029_ts_data *bu21029 = i2c_get_clientdata(i2c);
432
433 if (!device_may_wakeup(dev)) {
434 mutex_lock(&bu21029->in_dev->mutex);
435 if (input_device_enabled(bu21029->in_dev))
436 bu21029_start_chip(bu21029->in_dev);
437 mutex_unlock(&bu21029->in_dev->mutex);
438 }
439
440 return 0;
441 }
442 static DEFINE_SIMPLE_DEV_PM_OPS(bu21029_pm_ops, bu21029_suspend, bu21029_resume);
443
444 static const struct i2c_device_id bu21029_ids[] = {
445 { DRIVER_NAME },
446 { /* sentinel */ }
447 };
448 MODULE_DEVICE_TABLE(i2c, bu21029_ids);
449
450 #ifdef CONFIG_OF
451 static const struct of_device_id bu21029_of_ids[] = {
452 { .compatible = "rohm,bu21029" },
453 { /* sentinel */ }
454 };
455 MODULE_DEVICE_TABLE(of, bu21029_of_ids);
456 #endif
457
458 static struct i2c_driver bu21029_driver = {
459 .driver = {
460 .name = DRIVER_NAME,
461 .of_match_table = of_match_ptr(bu21029_of_ids),
462 .pm = pm_sleep_ptr(&bu21029_pm_ops),
463 },
464 .id_table = bu21029_ids,
465 .probe = bu21029_probe,
466 };
467 module_i2c_driver(bu21029_driver);
468
469 MODULE_AUTHOR("Zhu Yi <yi.zhu5@cn.bosch.com>");
470 MODULE_DESCRIPTION("Rohm BU21029 touchscreen controller driver");
471 MODULE_LICENSE("GPL v2");
472