matrix_keypad.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  GPIO driven matrix keyboard driver
  4 *
  5 *  Copyright (c) 2008 Marek Vasut <marek.vasut@gmail.com>
  6 *
  7 *  Based on corgikbd.c
  8 */
  9
 10#include <linux/types.h>
 11#include <linux/delay.h>
 12#include <linux/gpio/consumer.h>
 13#include <linux/platform_device.h>
 14#include <linux/input.h>
 15#include <linux/irq.h>
 16#include <linux/interrupt.h>
 17#include <linux/jiffies.h>
 18#include <linux/module.h>
 19#include <linux/gpio.h>
 20#include <linux/input/matrix_keypad.h>
 21#include <linux/slab.h>
 22#include <linux/of.h>
 23
 24struct matrix_keypad {
 25	struct input_dev *input_dev;
 26	unsigned int row_shift;
 27
 28	unsigned int col_scan_delay_us;
 29	unsigned int all_cols_on_delay_us;
 30	/* key debounce interval in milli-second */
 31	unsigned int debounce_ms;
 32	bool drive_inactive_cols;
 33
 34	struct gpio_desc *row_gpios[MATRIX_MAX_ROWS];
 35	unsigned int num_row_gpios;
 36
 37	struct gpio_desc *col_gpios[MATRIX_MAX_ROWS];
 38	unsigned int num_col_gpios;
 39
 40	unsigned int row_irqs[MATRIX_MAX_ROWS];
 41	DECLARE_BITMAP(wakeup_enabled_irqs, MATRIX_MAX_ROWS);
 42
 43	uint32_t last_key_state[MATRIX_MAX_COLS];
 44	struct delayed_work work;
 45	spinlock_t lock;
 46	bool scan_pending;
 47	bool stopped;
 48};
 49
 50/*
 51 * NOTE: If drive_inactive_cols is false, then the GPIO has to be put into
 52 * HiZ when de-activated to cause minmal side effect when scanning other
 53 * columns. In that case it is configured here to be input, otherwise it is
 54 * driven with the inactive value.
 55 */
 56static void __activate_col(struct matrix_keypad *keypad, int col, bool on)
 57{
 58	if (on) {
 59		gpiod_direction_output(keypad->col_gpios[col], 1);
 60	} else {
 61		gpiod_set_value_cansleep(keypad->col_gpios[col], 0);
 62		if (!keypad->drive_inactive_cols)
 63			gpiod_direction_input(keypad->col_gpios[col]);
 64	}
 65}
 66
 67static void activate_col(struct matrix_keypad *keypad, int col, bool on)
 68{
 69	__activate_col(keypad, col, on);
 70
 71	if (on && keypad->col_scan_delay_us)
 72		fsleep(keypad->col_scan_delay_us);
 73}
 74
 75static void activate_all_cols(struct matrix_keypad *keypad, bool on)
 76{
 77	int col;
 78
 79	for (col = 0; col < keypad->num_col_gpios; col++)
 80		__activate_col(keypad, col, on);
 81
 82	if (on && keypad->all_cols_on_delay_us)
 83		fsleep(keypad->all_cols_on_delay_us);
 84}
 85
 86static bool row_asserted(struct matrix_keypad *keypad, int row)
 87{
 88	return gpiod_get_value_cansleep(keypad->row_gpios[row]);
 89}
 90
 91static void enable_row_irqs(struct matrix_keypad *keypad)
 92{
 93	int i;
 94
 95	for (i = 0; i < keypad->num_row_gpios; i++)
 96		enable_irq(keypad->row_irqs[i]);
 97}
 98
 99static void disable_row_irqs(struct matrix_keypad *keypad)
100{
101	int i;
102
103	for (i = 0; i < keypad->num_row_gpios; i++)
104		disable_irq_nosync(keypad->row_irqs[i]);
105}
106
107static uint32_t read_row_state(struct matrix_keypad *keypad)
108{
109	int row;
110	u32 row_state = 0;
111
112	for (row = 0; row < keypad->num_row_gpios; row++)
113		row_state |= row_asserted(keypad, row) ? BIT(row) : 0;
114	return row_state;
115}
116
117/*
118 * This gets the keys from keyboard and reports it to input subsystem
119 */
120static void matrix_keypad_scan(struct work_struct *work)
121{
122	struct matrix_keypad *keypad =
123		container_of(work, struct matrix_keypad, work.work);
124	struct input_dev *input_dev = keypad->input_dev;
125	const unsigned short *keycodes = input_dev->keycode;
126	uint32_t new_state[MATRIX_MAX_COLS];
127	int row, col, code;
128	u32 init_row_state, new_row_state;
129
130	/* read initial row state to detect changes between scan */
131	init_row_state = read_row_state(keypad);
132
133	/* de-activate all columns for scanning */
134	activate_all_cols(keypad, false);
135
136	memset(new_state, 0, sizeof(new_state));
137
138	for (row = 0; row < keypad->num_row_gpios; row++)
139		gpiod_direction_input(keypad->row_gpios[row]);
140
141	/* assert each column and read the row status out */
142	for (col = 0; col < keypad->num_col_gpios; col++) {
143
144		activate_col(keypad, col, true);
145
146		new_state[col] = read_row_state(keypad);
147
148		activate_col(keypad, col, false);
149	}
150
151	for (col = 0; col < keypad->num_col_gpios; col++) {
152		uint32_t bits_changed;
153
154		bits_changed = keypad->last_key_state[col] ^ new_state[col];
155		if (bits_changed == 0)
156			continue;
157
158		for (row = 0; row < keypad->num_row_gpios; row++) {
159			if (!(bits_changed & BIT(row)))
160				continue;
161
162			code = MATRIX_SCAN_CODE(row, col, keypad->row_shift);
163			input_event(input_dev, EV_MSC, MSC_SCAN, code);
164			input_report_key(input_dev,
165					 keycodes[code],
166					 new_state[col] & (1 << row));
167		}
168	}
169	input_sync(input_dev);
170
171	memcpy(keypad->last_key_state, new_state, sizeof(new_state));
172
173	activate_all_cols(keypad, true);
174
175	/* Enable IRQs again */
176	scoped_guard(spinlock_irq, &keypad->lock) {
177		keypad->scan_pending = false;
178		enable_row_irqs(keypad);
179	}
180
181	/* read new row state and detect if value has changed */
182	new_row_state = read_row_state(keypad);
183	if (init_row_state != new_row_state) {
184		guard(spinlock_irq)(&keypad->lock);
185		if (unlikely(keypad->scan_pending || keypad->stopped))
186			return;
187		disable_row_irqs(keypad);
188		keypad->scan_pending = true;
189		schedule_delayed_work(&keypad->work,
190				      msecs_to_jiffies(keypad->debounce_ms));
191	}
192}
193
194static irqreturn_t matrix_keypad_interrupt(int irq, void *id)
195{
196	struct matrix_keypad *keypad = id;
197
198	guard(spinlock_irqsave)(&keypad->lock);
199
200	/*
201	 * See if another IRQ beaten us to it and scheduled the
202	 * scan already. In that case we should not try to
203	 * disable IRQs again.
204	 */
205	if (unlikely(keypad->scan_pending || keypad->stopped))
206		goto out;
207
208	disable_row_irqs(keypad);
209	keypad->scan_pending = true;
210	schedule_delayed_work(&keypad->work,
211			      msecs_to_jiffies(keypad->debounce_ms));
212
213out:
214	return IRQ_HANDLED;
215}
216
217static int matrix_keypad_start(struct input_dev *dev)
218{
219	struct matrix_keypad *keypad = input_get_drvdata(dev);
220
221	keypad->stopped = false;
222	mb();
223
224	/*
225	 * Schedule an immediate key scan to capture current key state;
226	 * columns will be activated and IRQs be enabled after the scan.
227	 */
228	schedule_delayed_work(&keypad->work, 0);
229
230	return 0;
231}
232
233static void matrix_keypad_stop(struct input_dev *dev)
234{
235	struct matrix_keypad *keypad = input_get_drvdata(dev);
236
237	scoped_guard(spinlock_irq, &keypad->lock) {
238		keypad->stopped = true;
239	}
240
241	flush_delayed_work(&keypad->work);
242	/*
243	 * matrix_keypad_scan() will leave IRQs enabled;
244	 * we should disable them now.
245	 */
246	disable_row_irqs(keypad);
247}
248
249static void matrix_keypad_enable_wakeup(struct matrix_keypad *keypad)
250{
251	int i;
252
253	for_each_clear_bit(i, keypad->wakeup_enabled_irqs,
254			   keypad->num_row_gpios)
255		if (enable_irq_wake(keypad->row_irqs[i]) == 0)
256			__set_bit(i, keypad->wakeup_enabled_irqs);
257}
258
259static void matrix_keypad_disable_wakeup(struct matrix_keypad *keypad)
260{
261	int i;
262
263	for_each_set_bit(i, keypad->wakeup_enabled_irqs,
264			 keypad->num_row_gpios) {
265		disable_irq_wake(keypad->row_irqs[i]);
266		__clear_bit(i, keypad->wakeup_enabled_irqs);
267	}
268}
269
270static int matrix_keypad_suspend(struct device *dev)
271{
272	struct platform_device *pdev = to_platform_device(dev);
273	struct matrix_keypad *keypad = platform_get_drvdata(pdev);
274
275	matrix_keypad_stop(keypad->input_dev);
276
277	if (device_may_wakeup(&pdev->dev))
278		matrix_keypad_enable_wakeup(keypad);
279
280	return 0;
281}
282
283static int matrix_keypad_resume(struct device *dev)
284{
285	struct platform_device *pdev = to_platform_device(dev);
286	struct matrix_keypad *keypad = platform_get_drvdata(pdev);
287
288	if (device_may_wakeup(&pdev->dev))
289		matrix_keypad_disable_wakeup(keypad);
290
291	matrix_keypad_start(keypad->input_dev);
292
293	return 0;
294}
295
296static DEFINE_SIMPLE_DEV_PM_OPS(matrix_keypad_pm_ops,
297				matrix_keypad_suspend, matrix_keypad_resume);
298
299static int matrix_keypad_init_gpio(struct platform_device *pdev,
300				   struct matrix_keypad *keypad)
301{
302	bool active_low;
303	int nrow, ncol;
304	int err;
305	int i;
306
307	nrow = gpiod_count(&pdev->dev, "row");
308	ncol = gpiod_count(&pdev->dev, "col");
309	if (nrow < 0 || ncol < 0) {
310		dev_err(&pdev->dev, "missing row or column GPIOs\n");
311		return -EINVAL;
312	}
313
314	keypad->num_row_gpios = nrow;
315	keypad->num_col_gpios = ncol;
316
317	active_low = device_property_read_bool(&pdev->dev, "gpio-activelow");
318
319	/* initialize strobe lines as outputs, activated */
320	for (i = 0; i < keypad->num_col_gpios; i++) {
321		keypad->col_gpios[i] = devm_gpiod_get_index(&pdev->dev, "col",
322							    i, GPIOD_ASIS);
323		err = PTR_ERR_OR_ZERO(keypad->col_gpios[i]);
324		if (err) {
325			dev_err(&pdev->dev,
326				"failed to request GPIO for COL%d: %d\n",
327				i, err);
328			return err;
329		}
330
331		gpiod_set_consumer_name(keypad->col_gpios[i], "matrix_kbd_col");
332
333		if (active_low ^ gpiod_is_active_low(keypad->col_gpios[i]))
334			gpiod_toggle_active_low(keypad->col_gpios[i]);
335
336		gpiod_direction_output(keypad->col_gpios[i], 1);
337	}
338
339	for (i = 0; i < keypad->num_row_gpios; i++) {
340		keypad->row_gpios[i] = devm_gpiod_get_index(&pdev->dev, "row",
341							    i, GPIOD_IN);
342		err = PTR_ERR_OR_ZERO(keypad->row_gpios[i]);
343		if (err) {
344			dev_err(&pdev->dev,
345				"failed to request GPIO for ROW%d: %d\n",
346				i, err);
347			return err;
348		}
349
350		gpiod_set_consumer_name(keypad->row_gpios[i], "matrix_kbd_row");
351
352		if (active_low ^ gpiod_is_active_low(keypad->row_gpios[i]))
353			gpiod_toggle_active_low(keypad->row_gpios[i]);
354	}
355
356	return 0;
357}
358
359static int matrix_keypad_setup_interrupts(struct platform_device *pdev,
360					  struct matrix_keypad *keypad)
361{
362	int err;
363	int irq;
364	int i;
365
366	for (i = 0; i < keypad->num_row_gpios; i++) {
367		irq = gpiod_to_irq(keypad->row_gpios[i]);
368		if (irq < 0) {
369			err = irq;
370			dev_err(&pdev->dev,
371				"Unable to convert GPIO line %i to irq: %d\n",
372				i, err);
373			return err;
374		}
375
376		err = devm_request_any_context_irq(&pdev->dev, irq,
377						   matrix_keypad_interrupt,
378						   IRQF_TRIGGER_RISING |
379							IRQF_TRIGGER_FALLING,
380						   "matrix-keypad", keypad);
381		if (err < 0) {
382			dev_err(&pdev->dev,
383				"Unable to acquire interrupt for row %i: %d\n",
384				i, err);
385			return err;
386		}
387
388		keypad->row_irqs[i] = irq;
389	}
390
391	/* initialized as disabled - enabled by input->open */
392	disable_row_irqs(keypad);
393
394	return 0;
395}
396
397static int matrix_keypad_probe(struct platform_device *pdev)
398{
399	struct matrix_keypad *keypad;
400	struct input_dev *input_dev;
401	bool wakeup;
402	int err;
403
404	keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
405	if (!keypad)
406		return -ENOMEM;
407
408	input_dev = devm_input_allocate_device(&pdev->dev);
409	if (!input_dev)
410		return -ENOMEM;
411
412	keypad->input_dev = input_dev;
413	keypad->stopped = true;
414	INIT_DELAYED_WORK(&keypad->work, matrix_keypad_scan);
415	spin_lock_init(&keypad->lock);
416
417	keypad->drive_inactive_cols =
418		device_property_read_bool(&pdev->dev, "drive-inactive-cols");
419	device_property_read_u32(&pdev->dev, "debounce-delay-ms",
420				 &keypad->debounce_ms);
421	device_property_read_u32(&pdev->dev, "col-scan-delay-us",
422				 &keypad->col_scan_delay_us);
423	device_property_read_u32(&pdev->dev, "all-cols-on-delay-us",
424				 &keypad->all_cols_on_delay_us);
425
426	err = matrix_keypad_init_gpio(pdev, keypad);
427	if (err)
428		return err;
429
430	keypad->row_shift = get_count_order(keypad->num_col_gpios);
431
432	err = matrix_keypad_setup_interrupts(pdev, keypad);
433	if (err)
434		return err;
435
436	input_dev->name		= pdev->name;
437	input_dev->id.bustype	= BUS_HOST;
438	input_dev->open		= matrix_keypad_start;
439	input_dev->close	= matrix_keypad_stop;
440
441	err = matrix_keypad_build_keymap(NULL, NULL,
442					 keypad->num_row_gpios,
443					 keypad->num_col_gpios,
444					 NULL, input_dev);
445	if (err) {
446		dev_err(&pdev->dev, "failed to build keymap\n");
447		return -ENOMEM;
448	}
449
450	if (!device_property_read_bool(&pdev->dev, "linux,no-autorepeat"))
451		__set_bit(EV_REP, input_dev->evbit);
452
453	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
454	input_set_drvdata(input_dev, keypad);
455
456	err = input_register_device(keypad->input_dev);
457	if (err)
458		return err;
459
460	wakeup = device_property_read_bool(&pdev->dev, "wakeup-source") ||
461		 /* legacy */
462		 device_property_read_bool(&pdev->dev, "linux,wakeup");
463	device_init_wakeup(&pdev->dev, wakeup);
464
465	platform_set_drvdata(pdev, keypad);
466
467	return 0;
468}
469
470#ifdef CONFIG_OF
471static const struct of_device_id matrix_keypad_dt_match[] = {
472	{ .compatible = "gpio-matrix-keypad" },
473	{ }
474};
475MODULE_DEVICE_TABLE(of, matrix_keypad_dt_match);
476#endif
477
478static struct platform_driver matrix_keypad_driver = {
479	.probe		= matrix_keypad_probe,
480	.driver		= {
481		.name	= "matrix-keypad",
482		.pm	= pm_sleep_ptr(&matrix_keypad_pm_ops),
483		.of_match_table = of_match_ptr(matrix_keypad_dt_match),
484	},
485};
486module_platform_driver(matrix_keypad_driver);
487
488MODULE_AUTHOR("Marek Vasut <marek.vasut@gmail.com>");
489MODULE_DESCRIPTION("GPIO Driven Matrix Keypad Driver");
490MODULE_LICENSE("GPL v2");
491MODULE_ALIAS("platform:matrix-keypad");