tsc2007_core.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * drivers/input/touchscreen/tsc2007.c
  4 *
  5 * Copyright (c) 2008 MtekVision Co., Ltd.
  6 *	Kwangwoo Lee <kwlee@mtekvision.com>
  7 *
  8 * Using code from:
  9 *  - ads7846.c
 10 *	Copyright (c) 2005 David Brownell
 11 *	Copyright (c) 2006 Nokia Corporation
 12 *  - corgi_ts.c
 13 *	Copyright (C) 2004-2005 Richard Purdie
 14 *  - omap_ts.[hc], ads7846.h, ts_osk.c
 15 *	Copyright (C) 2002 MontaVista Software
 16 *	Copyright (C) 2004 Texas Instruments
 17 *	Copyright (C) 2005 Dirk Behme
 18 */
 19
 20#include <linux/module.h>
 21#include <linux/slab.h>
 22#include <linux/gpio/consumer.h>
 23#include <linux/input.h>
 24#include <linux/interrupt.h>
 25#include <linux/i2c.h>
 26#include <linux/math64.h>
 27#include <linux/mod_devicetable.h>
 28#include <linux/property.h>
 29#include <linux/platform_data/tsc2007.h>
 30#include "tsc2007.h"
 31
 32int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
 33{
 34	s32 data;
 35	u16 val;
 36
 37	data = i2c_smbus_read_word_data(tsc->client, cmd);
 38	if (data < 0) {
 39		dev_err(&tsc->client->dev, "i2c io error: %d\n", data);
 40		return data;
 41	}
 42
 43	/* The protocol and raw data format from i2c interface:
 44	 * S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
 45	 * Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit].
 46	 */
 47	val = swab16(data) >> 4;
 48
 49	dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x\n", data, val);
 50
 51	return val;
 52}
 53
 54static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
 55{
 56	/* y- still on; turn on only y+ (and ADC) */
 57	tc->y = tsc2007_xfer(tsc, READ_Y);
 58
 59	/* turn y- off, x+ on, then leave in lowpower */
 60	tc->x = tsc2007_xfer(tsc, READ_X);
 61
 62	/* turn y+ off, x- on; we'll use formula #1 */
 63	tc->z1 = tsc2007_xfer(tsc, READ_Z1);
 64	tc->z2 = tsc2007_xfer(tsc, READ_Z2);
 65
 66	/* Prepare for next touch reading - power down ADC, enable PENIRQ */
 67	tsc2007_xfer(tsc, PWRDOWN);
 68}
 69
 70u32 tsc2007_calculate_resistance(struct tsc2007 *tsc, struct ts_event *tc)
 71{
 72	u64 rt = 0;
 73
 74	/* range filtering */
 75	if (tc->x == MAX_12BIT)
 76		tc->x = 0;
 77
 78	if (likely(tc->x && tc->z1)) {
 79		/* compute touch resistance using equation #1 */
 80		rt = tc->z2 - tc->z1;
 81		rt *= tc->x;
 82		rt *= tsc->x_plate_ohms;
 83		rt = div_u64(rt, tc->z1);
 84		rt = (rt + 2047) >> 12;
 85	}
 86
 87	if (rt > U32_MAX)
 88		return U32_MAX;
 89	return (u32) rt;
 90}
 91
 92bool tsc2007_is_pen_down(struct tsc2007 *ts)
 93{
 94	/*
 95	 * NOTE: We can't rely on the pressure to determine the pen down
 96	 * state, even though this controller has a pressure sensor.
 97	 * The pressure value can fluctuate for quite a while after
 98	 * lifting the pen and in some cases may not even settle at the
 99	 * expected value.
100	 *
101	 * The only safe way to check for the pen up condition is in the
102	 * work function by reading the pen signal state (it's a GPIO
103	 * and IRQ). Unfortunately such callback is not always available,
104	 * in that case we assume that the pen is down and expect caller
105	 * to fall back on the pressure reading.
106	 */
107
108	if (!ts->get_pendown_state)
109		return true;
110
111	return ts->get_pendown_state(&ts->client->dev);
112}
113
114static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
115{
116	struct tsc2007 *ts = handle;
117	struct input_dev *input = ts->input;
118	struct ts_event tc;
119	u32 rt;
120
121	while (!ts->stopped && tsc2007_is_pen_down(ts)) {
122
123		/* pen is down, continue with the measurement */
124
125		mutex_lock(&ts->mlock);
126		tsc2007_read_values(ts, &tc);
127		mutex_unlock(&ts->mlock);
128
129		rt = tsc2007_calculate_resistance(ts, &tc);
130
131		if (!rt && !ts->get_pendown_state) {
132			/*
133			 * If pressure reported is 0 and we don't have
134			 * callback to check pendown state, we have to
135			 * assume that pen was lifted up.
136			 */
137			break;
138		}
139
140		if (rt <= ts->max_rt) {
141			dev_dbg(&ts->client->dev,
142				"DOWN point(%4d,%4d), resistance (%4u)\n",
143				tc.x, tc.y, rt);
144
145			rt = ts->max_rt - rt;
146
147			input_report_key(input, BTN_TOUCH, 1);
148			touchscreen_report_pos(input, &ts->prop, tc.x, tc.y, false);
149			input_report_abs(input, ABS_PRESSURE, rt);
150
151			input_sync(input);
152
153		} else {
154			/*
155			 * Sample found inconsistent by debouncing or pressure is
156			 * beyond the maximum. Don't report it to user space,
157			 * repeat at least once more the measurement.
158			 */
159			dev_dbg(&ts->client->dev, "ignored pressure %d\n", rt);
160		}
161
162		wait_event_timeout(ts->wait, ts->stopped, ts->poll_period);
163	}
164
165	dev_dbg(&ts->client->dev, "UP\n");
166
167	input_report_key(input, BTN_TOUCH, 0);
168	input_report_abs(input, ABS_PRESSURE, 0);
169	input_sync(input);
170
171	if (ts->clear_penirq)
172		ts->clear_penirq();
173
174	return IRQ_HANDLED;
175}
176
177static void tsc2007_stop(struct tsc2007 *ts)
178{
179	ts->stopped = true;
180	mb();
181	wake_up(&ts->wait);
182
183	if (ts->irq)
184		disable_irq(ts->irq);
185}
186
187static int tsc2007_open(struct input_dev *input_dev)
188{
189	struct tsc2007 *ts = input_get_drvdata(input_dev);
190	int err;
191
192	ts->stopped = false;
193	mb();
194
195	if (ts->irq)
196		enable_irq(ts->irq);
197
198	/* Prepare for touch readings - power down ADC and enable PENIRQ */
199	err = tsc2007_xfer(ts, PWRDOWN);
200	if (err < 0) {
201		tsc2007_stop(ts);
202		return err;
203	}
204
205	return 0;
206}
207
208static void tsc2007_close(struct input_dev *input_dev)
209{
210	struct tsc2007 *ts = input_get_drvdata(input_dev);
211
212	tsc2007_stop(ts);
213}
214
215static int tsc2007_get_pendown_state_gpio(struct device *dev)
216{
217	struct i2c_client *client = to_i2c_client(dev);
218	struct tsc2007 *ts = i2c_get_clientdata(client);
219
220	return gpiod_get_value_cansleep(ts->gpiod);
221}
222
223static int tsc2007_probe_properties(struct device *dev, struct tsc2007 *ts)
224{
225	u32 val32;
226	u64 val64;
227
228	if (!device_property_read_u32(dev, "ti,max-rt", &val32))
229		ts->max_rt = val32;
230	else
231		ts->max_rt = MAX_12BIT;
232
233	if (!device_property_read_u32(dev, "ti,fuzzx", &val32))
234		ts->fuzzx = val32;
235
236	if (!device_property_read_u32(dev, "ti,fuzzy", &val32))
237		ts->fuzzy = val32;
238
239	if (!device_property_read_u32(dev, "ti,fuzzz", &val32))
240		ts->fuzzz = val32;
241
242	if (!device_property_read_u64(dev, "ti,poll-period", &val64))
243		ts->poll_period = msecs_to_jiffies(val64);
244	else
245		ts->poll_period = msecs_to_jiffies(1);
246
247	if (!device_property_read_u32(dev, "ti,x-plate-ohms", &val32)) {
248		ts->x_plate_ohms = val32;
249	} else {
250		dev_err(dev, "Missing ti,x-plate-ohms device property\n");
251		return -EINVAL;
252	}
253
254	ts->gpiod = devm_gpiod_get_optional(dev, NULL, GPIOD_IN);
255	if (IS_ERR(ts->gpiod))
256		return PTR_ERR(ts->gpiod);
257
258	if (ts->gpiod)
259		ts->get_pendown_state = tsc2007_get_pendown_state_gpio;
260	else
261		dev_dbg(dev, "Pen down GPIO is not specified in properties\n");
262
263	return 0;
264}
265
266static int tsc2007_probe_pdev(struct device *dev, struct tsc2007 *ts,
267			      const struct tsc2007_platform_data *pdata,
268			      const struct i2c_device_id *id)
269{
270	ts->model             = pdata->model;
271	ts->x_plate_ohms      = pdata->x_plate_ohms;
272	ts->max_rt            = pdata->max_rt ? : MAX_12BIT;
273	ts->poll_period       = msecs_to_jiffies(pdata->poll_period ? : 1);
274	ts->get_pendown_state = pdata->get_pendown_state;
275	ts->clear_penirq      = pdata->clear_penirq;
276	ts->fuzzx             = pdata->fuzzx;
277	ts->fuzzy             = pdata->fuzzy;
278	ts->fuzzz             = pdata->fuzzz;
279
280	if (pdata->x_plate_ohms == 0) {
281		dev_err(dev, "x_plate_ohms is not set up in platform data\n");
282		return -EINVAL;
283	}
284
285	return 0;
286}
287
288static void tsc2007_call_exit_platform_hw(void *data)
289{
290	struct device *dev = data;
291	const struct tsc2007_platform_data *pdata = dev_get_platdata(dev);
292
293	pdata->exit_platform_hw();
294}
295
296static int tsc2007_probe(struct i2c_client *client)
297{
298	const struct i2c_device_id *id = i2c_client_get_device_id(client);
299	const struct tsc2007_platform_data *pdata =
300		dev_get_platdata(&client->dev);
301	struct tsc2007 *ts;
302	struct input_dev *input_dev;
303	int err;
304
305	if (!i2c_check_functionality(client->adapter,
306				     I2C_FUNC_SMBUS_READ_WORD_DATA))
307		return -EIO;
308
309	ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
310	if (!ts)
311		return -ENOMEM;
312
313	if (pdata)
314		err = tsc2007_probe_pdev(&client->dev, ts, pdata, id);
315	else
316		err = tsc2007_probe_properties(&client->dev, ts);
317	if (err)
318		return err;
319
320	input_dev = devm_input_allocate_device(&client->dev);
321	if (!input_dev)
322		return -ENOMEM;
323
324	i2c_set_clientdata(client, ts);
325
326	ts->client = client;
327	ts->irq = client->irq;
328	ts->input = input_dev;
329
330	init_waitqueue_head(&ts->wait);
331	mutex_init(&ts->mlock);
332
333	snprintf(ts->phys, sizeof(ts->phys),
334		 "%s/input0", dev_name(&client->dev));
335
336	input_dev->name = "TSC2007 Touchscreen";
337	input_dev->phys = ts->phys;
338	input_dev->id.bustype = BUS_I2C;
339
340	input_dev->open = tsc2007_open;
341	input_dev->close = tsc2007_close;
342
343	input_set_drvdata(input_dev, ts);
344
345	input_set_capability(input_dev, EV_KEY, BTN_TOUCH);
346	input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, ts->fuzzx, 0);
347	input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, ts->fuzzy, 0);
348	touchscreen_parse_properties(input_dev, false, &ts->prop);
349	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
350			     ts->fuzzz, 0);
351
352	if (pdata) {
353		if (pdata->exit_platform_hw) {
354			err = devm_add_action(&client->dev,
355					      tsc2007_call_exit_platform_hw,
356					      &client->dev);
357			if (err) {
358				dev_err(&client->dev,
359					"Failed to register exit_platform_hw action, %d\n",
360					err);
361				return err;
362			}
363		}
364
365		if (pdata->init_platform_hw)
366			pdata->init_platform_hw();
367	}
368
369	if (ts->irq) {
370		err = devm_request_threaded_irq(&client->dev, ts->irq,
371						NULL, tsc2007_soft_irq,
372						IRQF_ONESHOT,
373						client->dev.driver->name, ts);
374		if (err) {
375			dev_err(&client->dev, "Failed to request irq %d: %d\n",
376				ts->irq, err);
377			return err;
378		}
379
380		tsc2007_stop(ts);
381	}
382
383	/* power down the chip (TSC2007_SETUP does not ACK on I2C) */
384	err = tsc2007_xfer(ts, PWRDOWN);
385	if (err < 0) {
386		dev_err(&client->dev,
387			"Failed to setup chip: %d\n", err);
388		return err;	/* chip does not respond */
389	}
390
391	err = input_register_device(input_dev);
392	if (err) {
393		dev_err(&client->dev,
394			"Failed to register input device: %d\n", err);
395		return err;
396	}
397
398	err =  tsc2007_iio_configure(ts);
399	if (err) {
400		dev_err(&client->dev,
401			"Failed to register with IIO: %d\n", err);
402		return err;
403	}
404
405	return 0;
406}
407
408static const struct i2c_device_id tsc2007_idtable[] = {
409	{ "tsc2007" },
410	{ }
411};
412
413MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);
414
415static const struct of_device_id tsc2007_of_match[] = {
416	{ .compatible = "ti,tsc2007" },
417	{ /* sentinel */ }
418};
419MODULE_DEVICE_TABLE(of, tsc2007_of_match);
420
421static struct i2c_driver tsc2007_driver = {
422	.driver = {
423		.name	= "tsc2007",
424		.of_match_table = tsc2007_of_match,
425	},
426	.id_table	= tsc2007_idtable,
427	.probe		= tsc2007_probe,
428};
429
430module_i2c_driver(tsc2007_driver);
431
432MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>");
433MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
434MODULE_LICENSE("GPL");