imx_keypad.c

  1// SPDX-License-Identifier: GPL-2.0
  2//
  3// Driver for the IMX keypad port.
  4// Copyright (C) 2009 Alberto Panizzo <maramaopercheseimorto@gmail.com>
  5
  6#include <linux/clk.h>
  7#include <linux/delay.h>
  8#include <linux/device.h>
  9#include <linux/err.h>
 10#include <linux/input.h>
 11#include <linux/input/matrix_keypad.h>
 12#include <linux/interrupt.h>
 13#include <linux/io.h>
 14#include <linux/jiffies.h>
 15#include <linux/kernel.h>
 16#include <linux/module.h>
 17#include <linux/of.h>
 18#include <linux/platform_device.h>
 19#include <linux/slab.h>
 20#include <linux/timer.h>
 21
 22/*
 23 * Keypad Controller registers (halfword)
 24 */
 25#define KPCR		0x00 /* Keypad Control Register */
 26
 27#define KPSR		0x02 /* Keypad Status Register */
 28#define KBD_STAT_KPKD	(0x1 << 0) /* Key Press Interrupt Status bit (w1c) */
 29#define KBD_STAT_KPKR	(0x1 << 1) /* Key Release Interrupt Status bit (w1c) */
 30#define KBD_STAT_KDSC	(0x1 << 2) /* Key Depress Synch Chain Status bit (w1c)*/
 31#define KBD_STAT_KRSS	(0x1 << 3) /* Key Release Synch Status bit (w1c)*/
 32#define KBD_STAT_KDIE	(0x1 << 8) /* Key Depress Interrupt Enable Status bit */
 33#define KBD_STAT_KRIE	(0x1 << 9) /* Key Release Interrupt Enable */
 34#define KBD_STAT_KPPEN	(0x1 << 10) /* Keypad Clock Enable */
 35
 36#define KDDR		0x04 /* Keypad Data Direction Register */
 37#define KPDR		0x06 /* Keypad Data Register */
 38
 39#define MAX_MATRIX_KEY_ROWS	8
 40#define MAX_MATRIX_KEY_COLS	8
 41#define MATRIX_ROW_SHIFT	3
 42
 43#define MAX_MATRIX_KEY_NUM	(MAX_MATRIX_KEY_ROWS * MAX_MATRIX_KEY_COLS)
 44
 45struct imx_keypad {
 46
 47	struct clk *clk;
 48	struct input_dev *input_dev;
 49	void __iomem *mmio_base;
 50
 51	int			irq;
 52	struct timer_list	check_matrix_timer;
 53
 54	/*
 55	 * The matrix is stable only if no changes are detected after
 56	 * IMX_KEYPAD_SCANS_FOR_STABILITY scans
 57	 */
 58#define IMX_KEYPAD_SCANS_FOR_STABILITY 3
 59	int			stable_count;
 60
 61	bool			enabled;
 62
 63	/* Masks for enabled rows/cols */
 64	unsigned short		rows_en_mask;
 65	unsigned short		cols_en_mask;
 66
 67	unsigned short		keycodes[MAX_MATRIX_KEY_NUM];
 68
 69	/*
 70	 * Matrix states:
 71	 * -stable: achieved after a complete debounce process.
 72	 * -unstable: used in the debouncing process.
 73	 */
 74	unsigned short		matrix_stable_state[MAX_MATRIX_KEY_COLS];
 75	unsigned short		matrix_unstable_state[MAX_MATRIX_KEY_COLS];
 76};
 77
 78/* Scan the matrix and return the new state in *matrix_volatile_state. */
 79static void imx_keypad_scan_matrix(struct imx_keypad *keypad,
 80				  unsigned short *matrix_volatile_state)
 81{
 82	int col;
 83	unsigned short reg_val;
 84
 85	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
 86		if ((keypad->cols_en_mask & (1 << col)) == 0)
 87			continue;
 88		/*
 89		 * Discharge keypad capacitance:
 90		 * 2. write 1s on column data.
 91		 * 3. configure columns as totem-pole to discharge capacitance.
 92		 * 4. configure columns as open-drain.
 93		 */
 94		reg_val = readw(keypad->mmio_base + KPDR);
 95		reg_val |= 0xff00;
 96		writew(reg_val, keypad->mmio_base + KPDR);
 97
 98		reg_val = readw(keypad->mmio_base + KPCR);
 99		reg_val &= ~((keypad->cols_en_mask & 0xff) << 8);
100		writew(reg_val, keypad->mmio_base + KPCR);
101
102		udelay(2);
103
104		reg_val = readw(keypad->mmio_base + KPCR);
105		reg_val |= (keypad->cols_en_mask & 0xff) << 8;
106		writew(reg_val, keypad->mmio_base + KPCR);
107
108		/*
109		 * 5. Write a single column to 0, others to 1.
110		 * 6. Sample row inputs and save data.
111		 * 7. Repeat steps 2 - 6 for remaining columns.
112		 */
113		reg_val = readw(keypad->mmio_base + KPDR);
114		reg_val &= ~(1 << (8 + col));
115		writew(reg_val, keypad->mmio_base + KPDR);
116
117		/*
118		 * Delay added to avoid propagating the 0 from column to row
119		 * when scanning.
120		 */
121		udelay(5);
122
123		/*
124		 * 1s in matrix_volatile_state[col] means key pressures
125		 * throw data from non enabled rows.
126		 */
127		reg_val = readw(keypad->mmio_base + KPDR);
128		matrix_volatile_state[col] = (~reg_val) & keypad->rows_en_mask;
129	}
130
131	/*
132	 * Return in standby mode:
133	 * 9. write 0s to columns
134	 */
135	reg_val = readw(keypad->mmio_base + KPDR);
136	reg_val &= 0x00ff;
137	writew(reg_val, keypad->mmio_base + KPDR);
138}
139
140/*
141 * Compare the new matrix state (volatile) with the stable one stored in
142 * keypad->matrix_stable_state and fire events if changes are detected.
143 */
144static void imx_keypad_fire_events(struct imx_keypad *keypad,
145				   unsigned short *matrix_volatile_state)
146{
147	struct input_dev *input_dev = keypad->input_dev;
148	int row, col;
149
150	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
151		unsigned short bits_changed;
152		int code;
153
154		if ((keypad->cols_en_mask & (1 << col)) == 0)
155			continue; /* Column is not enabled */
156
157		bits_changed = keypad->matrix_stable_state[col] ^
158						matrix_volatile_state[col];
159
160		if (bits_changed == 0)
161			continue; /* Column does not contain changes */
162
163		for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
164			if ((keypad->rows_en_mask & (1 << row)) == 0)
165				continue; /* Row is not enabled */
166			if ((bits_changed & (1 << row)) == 0)
167				continue; /* Row does not contain changes */
168
169			code = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
170			input_event(input_dev, EV_MSC, MSC_SCAN, code);
171			input_report_key(input_dev, keypad->keycodes[code],
172				matrix_volatile_state[col] & (1 << row));
173			dev_dbg(&input_dev->dev, "Event code: %d, val: %d",
174				keypad->keycodes[code],
175				matrix_volatile_state[col] & (1 << row));
176		}
177	}
178	input_sync(input_dev);
179}
180
181/*
182 * imx_keypad_check_for_events is the timer handler.
183 */
184static void imx_keypad_check_for_events(struct timer_list *t)
185{
186	struct imx_keypad *keypad = timer_container_of(keypad, t,
187						       check_matrix_timer);
188	unsigned short matrix_volatile_state[MAX_MATRIX_KEY_COLS];
189	unsigned short reg_val;
190	bool state_changed, is_zero_matrix;
191	int i;
192
193	memset(matrix_volatile_state, 0, sizeof(matrix_volatile_state));
194
195	imx_keypad_scan_matrix(keypad, matrix_volatile_state);
196
197	state_changed = false;
198	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
199		if ((keypad->cols_en_mask & (1 << i)) == 0)
200			continue;
201
202		if (keypad->matrix_unstable_state[i] ^ matrix_volatile_state[i]) {
203			state_changed = true;
204			break;
205		}
206	}
207
208	/*
209	 * If the matrix state is changed from the previous scan
210	 *   (Re)Begin the debouncing process, saving the new state in
211	 *    keypad->matrix_unstable_state.
212	 * else
213	 *   Increase the count of number of scans with a stable state.
214	 */
215	if (state_changed) {
216		memcpy(keypad->matrix_unstable_state, matrix_volatile_state,
217			sizeof(matrix_volatile_state));
218		keypad->stable_count = 0;
219	} else
220		keypad->stable_count++;
221
222	/*
223	 * If the matrix is not as stable as we want reschedule scan
224	 * in the near future.
225	 */
226	if (keypad->stable_count < IMX_KEYPAD_SCANS_FOR_STABILITY) {
227		mod_timer(&keypad->check_matrix_timer,
228			  jiffies + msecs_to_jiffies(10));
229		return;
230	}
231
232	/*
233	 * If the matrix state is stable, fire the events and save the new
234	 * stable state. Note, if the matrix is kept stable for longer
235	 * (keypad->stable_count > IMX_KEYPAD_SCANS_FOR_STABILITY) all
236	 * events have already been generated.
237	 */
238	if (keypad->stable_count == IMX_KEYPAD_SCANS_FOR_STABILITY) {
239		imx_keypad_fire_events(keypad, matrix_volatile_state);
240
241		memcpy(keypad->matrix_stable_state, matrix_volatile_state,
242			sizeof(matrix_volatile_state));
243	}
244
245	is_zero_matrix = true;
246	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
247		if (matrix_volatile_state[i] != 0) {
248			is_zero_matrix = false;
249			break;
250		}
251	}
252
253
254	if (is_zero_matrix) {
255		/*
256		 * All keys have been released. Enable only the KDI
257		 * interrupt for future key presses (clear the KDI
258		 * status bit and its sync chain before that).
259		 */
260		reg_val = readw(keypad->mmio_base + KPSR);
261		reg_val |= KBD_STAT_KPKD | KBD_STAT_KDSC;
262		writew(reg_val, keypad->mmio_base + KPSR);
263
264		reg_val = readw(keypad->mmio_base + KPSR);
265		reg_val |= KBD_STAT_KDIE;
266		reg_val &= ~KBD_STAT_KRIE;
267		writew(reg_val, keypad->mmio_base + KPSR);
268	} else {
269		/*
270		 * Some keys are still pressed. Schedule a rescan in
271		 * attempt to detect multiple key presses and enable
272		 * the KRI interrupt to react quickly to key release
273		 * event.
274		 */
275		mod_timer(&keypad->check_matrix_timer,
276			  jiffies + msecs_to_jiffies(60));
277
278		reg_val = readw(keypad->mmio_base + KPSR);
279		reg_val |= KBD_STAT_KPKR | KBD_STAT_KRSS;
280		writew(reg_val, keypad->mmio_base + KPSR);
281
282		reg_val = readw(keypad->mmio_base + KPSR);
283		reg_val |= KBD_STAT_KRIE;
284		reg_val &= ~KBD_STAT_KDIE;
285		writew(reg_val, keypad->mmio_base + KPSR);
286	}
287}
288
289static irqreturn_t imx_keypad_irq_handler(int irq, void *dev_id)
290{
291	struct imx_keypad *keypad = dev_id;
292	unsigned short reg_val;
293
294	reg_val = readw(keypad->mmio_base + KPSR);
295
296	/* Disable both interrupt types */
297	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
298	/* Clear interrupts status bits */
299	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
300	writew(reg_val, keypad->mmio_base + KPSR);
301
302	if (keypad->enabled) {
303		/* The matrix is supposed to be changed */
304		keypad->stable_count = 0;
305
306		/* Schedule the scanning procedure near in the future */
307		mod_timer(&keypad->check_matrix_timer,
308			  jiffies + msecs_to_jiffies(2));
309	}
310
311	return IRQ_HANDLED;
312}
313
314static void imx_keypad_config(struct imx_keypad *keypad)
315{
316	unsigned short reg_val;
317
318	/*
319	 * Include enabled rows in interrupt generation (KPCR[7:0])
320	 * Configure keypad columns as open-drain (KPCR[15:8])
321	 */
322	reg_val = readw(keypad->mmio_base + KPCR);
323	reg_val |= keypad->rows_en_mask & 0xff;		/* rows */
324	reg_val |= (keypad->cols_en_mask & 0xff) << 8;	/* cols */
325	writew(reg_val, keypad->mmio_base + KPCR);
326
327	/* Write 0's to KPDR[15:8] (Colums) */
328	reg_val = readw(keypad->mmio_base + KPDR);
329	reg_val &= 0x00ff;
330	writew(reg_val, keypad->mmio_base + KPDR);
331
332	/* Configure columns as output, rows as input (KDDR[15:0]) */
333	writew(0xff00, keypad->mmio_base + KDDR);
334
335	/*
336	 * Clear Key Depress and Key Release status bit.
337	 * Clear both synchronizer chain.
338	 */
339	reg_val = readw(keypad->mmio_base + KPSR);
340	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD |
341		   KBD_STAT_KDSC | KBD_STAT_KRSS;
342	writew(reg_val, keypad->mmio_base + KPSR);
343
344	/* Enable KDI and disable KRI (avoid false release events). */
345	reg_val |= KBD_STAT_KDIE;
346	reg_val &= ~KBD_STAT_KRIE;
347	writew(reg_val, keypad->mmio_base + KPSR);
348}
349
350static void imx_keypad_inhibit(struct imx_keypad *keypad)
351{
352	unsigned short reg_val;
353
354	/* Inhibit KDI and KRI interrupts. */
355	reg_val = readw(keypad->mmio_base + KPSR);
356	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
357	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
358	writew(reg_val, keypad->mmio_base + KPSR);
359
360	/* Colums as open drain and disable all rows */
361	reg_val = (keypad->cols_en_mask & 0xff) << 8;
362	writew(reg_val, keypad->mmio_base + KPCR);
363}
364
365static void imx_keypad_close(struct input_dev *dev)
366{
367	struct imx_keypad *keypad = input_get_drvdata(dev);
368
369	dev_dbg(&dev->dev, ">%s\n", __func__);
370
371	/* Mark keypad as being inactive */
372	keypad->enabled = false;
373	synchronize_irq(keypad->irq);
374	timer_delete_sync(&keypad->check_matrix_timer);
375
376	imx_keypad_inhibit(keypad);
377
378	/* Disable clock unit */
379	clk_disable_unprepare(keypad->clk);
380}
381
382static int imx_keypad_open(struct input_dev *dev)
383{
384	struct imx_keypad *keypad = input_get_drvdata(dev);
385	int error;
386
387	dev_dbg(&dev->dev, ">%s\n", __func__);
388
389	/* Enable the kpp clock */
390	error = clk_prepare_enable(keypad->clk);
391	if (error)
392		return error;
393
394	/* We became active from now */
395	keypad->enabled = true;
396
397	imx_keypad_config(keypad);
398
399	/* Sanity control, not all the rows must be actived now. */
400	if ((readw(keypad->mmio_base + KPDR) & keypad->rows_en_mask) == 0) {
401		dev_err(&dev->dev,
402			"too many keys pressed, control pins initialisation\n");
403		goto open_err;
404	}
405
406	return 0;
407
408open_err:
409	imx_keypad_close(dev);
410	return -EIO;
411}
412
413static const struct of_device_id imx_keypad_of_match[] = {
414	{ .compatible = "fsl,imx21-kpp", },
415	{ /* sentinel */ }
416};
417MODULE_DEVICE_TABLE(of, imx_keypad_of_match);
418
419static int imx_keypad_probe(struct platform_device *pdev)
420{
421	struct imx_keypad *keypad;
422	struct input_dev *input_dev;
423	int irq, error, i, row, col;
424
425	irq = platform_get_irq(pdev, 0);
426	if (irq < 0)
427		return irq;
428
429	input_dev = devm_input_allocate_device(&pdev->dev);
430	if (!input_dev) {
431		dev_err(&pdev->dev, "failed to allocate the input device\n");
432		return -ENOMEM;
433	}
434
435	keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
436	if (!keypad) {
437		dev_err(&pdev->dev, "not enough memory for driver data\n");
438		return -ENOMEM;
439	}
440
441	keypad->input_dev = input_dev;
442	keypad->irq = irq;
443	keypad->stable_count = 0;
444
445	timer_setup(&keypad->check_matrix_timer,
446		    imx_keypad_check_for_events, 0);
447
448	keypad->mmio_base = devm_platform_ioremap_resource(pdev, 0);
449	if (IS_ERR(keypad->mmio_base))
450		return PTR_ERR(keypad->mmio_base);
451
452	keypad->clk = devm_clk_get(&pdev->dev, NULL);
453	if (IS_ERR(keypad->clk)) {
454		dev_err(&pdev->dev, "failed to get keypad clock\n");
455		return PTR_ERR(keypad->clk);
456	}
457
458	/* Init the Input device */
459	input_dev->name = pdev->name;
460	input_dev->id.bustype = BUS_HOST;
461	input_dev->dev.parent = &pdev->dev;
462	input_dev->open = imx_keypad_open;
463	input_dev->close = imx_keypad_close;
464
465	error = matrix_keypad_build_keymap(NULL, NULL,
466					   MAX_MATRIX_KEY_ROWS,
467					   MAX_MATRIX_KEY_COLS,
468					   keypad->keycodes, input_dev);
469	if (error) {
470		dev_err(&pdev->dev, "failed to build keymap\n");
471		return error;
472	}
473
474	/* Search for rows and cols enabled */
475	for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
476		for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
477			i = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
478			if (keypad->keycodes[i] != KEY_RESERVED) {
479				keypad->rows_en_mask |= 1 << row;
480				keypad->cols_en_mask |= 1 << col;
481			}
482		}
483	}
484	dev_dbg(&pdev->dev, "enabled rows mask: %x\n", keypad->rows_en_mask);
485	dev_dbg(&pdev->dev, "enabled cols mask: %x\n", keypad->cols_en_mask);
486
487	__set_bit(EV_REP, input_dev->evbit);
488	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
489	input_set_drvdata(input_dev, keypad);
490
491	/* Ensure that the keypad will stay dormant until opened */
492	error = clk_prepare_enable(keypad->clk);
493	if (error)
494		return error;
495	imx_keypad_inhibit(keypad);
496	clk_disable_unprepare(keypad->clk);
497
498	error = devm_request_irq(&pdev->dev, irq, imx_keypad_irq_handler, 0,
499			    pdev->name, keypad);
500	if (error) {
501		dev_err(&pdev->dev, "failed to request IRQ\n");
502		return error;
503	}
504
505	/* Register the input device */
506	error = input_register_device(input_dev);
507	if (error) {
508		dev_err(&pdev->dev, "failed to register input device\n");
509		return error;
510	}
511
512	platform_set_drvdata(pdev, keypad);
513	device_init_wakeup(&pdev->dev, 1);
514
515	return 0;
516}
517
518static int __maybe_unused imx_kbd_noirq_suspend(struct device *dev)
519{
520	struct platform_device *pdev = to_platform_device(dev);
521	struct imx_keypad *kbd = platform_get_drvdata(pdev);
522	struct input_dev *input_dev = kbd->input_dev;
523	unsigned short reg_val = readw(kbd->mmio_base + KPSR);
524
525	scoped_guard(mutex, &input_dev->mutex) {
526		/* imx kbd can wake up system even clock is disabled */
527		if (input_device_enabled(input_dev))
528			clk_disable_unprepare(kbd->clk);
529	}
530
531	if (device_may_wakeup(&pdev->dev)) {
532		if (reg_val & KBD_STAT_KPKD)
533			reg_val |= KBD_STAT_KRIE;
534		if (reg_val & KBD_STAT_KPKR)
535			reg_val |= KBD_STAT_KDIE;
536		writew(reg_val, kbd->mmio_base + KPSR);
537
538		enable_irq_wake(kbd->irq);
539	}
540
541	return 0;
542}
543
544static int __maybe_unused imx_kbd_noirq_resume(struct device *dev)
545{
546	struct platform_device *pdev = to_platform_device(dev);
547	struct imx_keypad *kbd = platform_get_drvdata(pdev);
548	struct input_dev *input_dev = kbd->input_dev;
549	int error;
550
551	if (device_may_wakeup(&pdev->dev))
552		disable_irq_wake(kbd->irq);
553
554	guard(mutex)(&input_dev->mutex);
555
556	if (input_device_enabled(input_dev)) {
557		error = clk_prepare_enable(kbd->clk);
558		if (error)
559			return error;
560	}
561
562	return 0;
563}
564
565static const struct dev_pm_ops imx_kbd_pm_ops = {
566	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_kbd_noirq_suspend, imx_kbd_noirq_resume)
567};
568
569static struct platform_driver imx_keypad_driver = {
570	.driver		= {
571		.name	= "imx-keypad",
572		.pm	= &imx_kbd_pm_ops,
573		.of_match_table = imx_keypad_of_match,
574	},
575	.probe		= imx_keypad_probe,
576};
577module_platform_driver(imx_keypad_driver);
578
579MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
580MODULE_DESCRIPTION("IMX Keypad Port Driver");
581MODULE_LICENSE("GPL v2");
582MODULE_ALIAS("platform:imx-keypad");