bu21029_ts.c

  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
155struct 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
165static 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
210static 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
220static 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
241out:
242	return IRQ_HANDLED;
243}
244
245static 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
253static 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
318err_out:
319	bu21029_put_chip_in_reset(bu21029);
320	regulator_disable(bu21029->vdd);
321	return error;
322}
323
324static 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
335static 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
413static 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
428static 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}
442static DEFINE_SIMPLE_DEV_PM_OPS(bu21029_pm_ops, bu21029_suspend, bu21029_resume);
443
444static const struct i2c_device_id bu21029_ids[] = {
445	{ DRIVER_NAME },
446	{ /* sentinel */ }
447};
448MODULE_DEVICE_TABLE(i2c, bu21029_ids);
449
450#ifdef CONFIG_OF
451static const struct of_device_id bu21029_of_ids[] = {
452	{ .compatible = "rohm,bu21029" },
453	{ /* sentinel */ }
454};
455MODULE_DEVICE_TABLE(of, bu21029_of_ids);
456#endif
457
458static 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};
467module_i2c_driver(bu21029_driver);
468
469MODULE_AUTHOR("Zhu Yi <yi.zhu5@cn.bosch.com>");
470MODULE_DESCRIPTION("Rohm BU21029 touchscreen controller driver");
471MODULE_LICENSE("GPL v2");