xref: /linux/drivers/input/keyboard/imx_keypad.c (revision be54f8c558027a218423134dd9b8c7c46d92204a)
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 
45 struct 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. */
imx_keypad_scan_matrix(struct imx_keypad * keypad,unsigned short * matrix_volatile_state)79 static 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  */
imx_keypad_fire_events(struct imx_keypad * keypad,unsigned short * matrix_volatile_state)144 static 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  */
imx_keypad_check_for_events(struct timer_list * t)184 static 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 
imx_keypad_irq_handler(int irq,void * dev_id)289 static 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 
imx_keypad_config(struct imx_keypad * keypad)314 static 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 
imx_keypad_inhibit(struct imx_keypad * keypad)350 static 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 
imx_keypad_close(struct input_dev * dev)365 static 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 
imx_keypad_open(struct input_dev * dev)382 static 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 
408 open_err:
409 	imx_keypad_close(dev);
410 	return -EIO;
411 }
412 
413 static const struct of_device_id imx_keypad_of_match[] = {
414 	{ .compatible = "fsl,imx21-kpp", },
415 	{ /* sentinel */ }
416 };
417 MODULE_DEVICE_TABLE(of, imx_keypad_of_match);
418 
imx_keypad_probe(struct platform_device * pdev)419 static 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 
imx_kbd_noirq_suspend(struct device * dev)518 static 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 
imx_kbd_noirq_resume(struct device * dev)544 static 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 
565 static 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 
569 static 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 };
577 module_platform_driver(imx_keypad_driver);
578 
579 MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
580 MODULE_DESCRIPTION("IMX Keypad Port Driver");
581 MODULE_LICENSE("GPL v2");
582 MODULE_ALIAS("platform:imx-keypad");
583