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. */
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  */
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  */
184 static void imx_keypad_check_for_events(struct timer_list *t)
185 {
186 	struct imx_keypad *keypad = from_timer(keypad, t, check_matrix_timer);
187 	unsigned short matrix_volatile_state[MAX_MATRIX_KEY_COLS];
188 	unsigned short reg_val;
189 	bool state_changed, is_zero_matrix;
190 	int i;
191 
192 	memset(matrix_volatile_state, 0, sizeof(matrix_volatile_state));
193 
194 	imx_keypad_scan_matrix(keypad, matrix_volatile_state);
195 
196 	state_changed = false;
197 	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
198 		if ((keypad->cols_en_mask & (1 << i)) == 0)
199 			continue;
200 
201 		if (keypad->matrix_unstable_state[i] ^ matrix_volatile_state[i]) {
202 			state_changed = true;
203 			break;
204 		}
205 	}
206 
207 	/*
208 	 * If the matrix state is changed from the previous scan
209 	 *   (Re)Begin the debouncing process, saving the new state in
210 	 *    keypad->matrix_unstable_state.
211 	 * else
212 	 *   Increase the count of number of scans with a stable state.
213 	 */
214 	if (state_changed) {
215 		memcpy(keypad->matrix_unstable_state, matrix_volatile_state,
216 			sizeof(matrix_volatile_state));
217 		keypad->stable_count = 0;
218 	} else
219 		keypad->stable_count++;
220 
221 	/*
222 	 * If the matrix is not as stable as we want reschedule scan
223 	 * in the near future.
224 	 */
225 	if (keypad->stable_count < IMX_KEYPAD_SCANS_FOR_STABILITY) {
226 		mod_timer(&keypad->check_matrix_timer,
227 			  jiffies + msecs_to_jiffies(10));
228 		return;
229 	}
230 
231 	/*
232 	 * If the matrix state is stable, fire the events and save the new
233 	 * stable state. Note, if the matrix is kept stable for longer
234 	 * (keypad->stable_count > IMX_KEYPAD_SCANS_FOR_STABILITY) all
235 	 * events have already been generated.
236 	 */
237 	if (keypad->stable_count == IMX_KEYPAD_SCANS_FOR_STABILITY) {
238 		imx_keypad_fire_events(keypad, matrix_volatile_state);
239 
240 		memcpy(keypad->matrix_stable_state, matrix_volatile_state,
241 			sizeof(matrix_volatile_state));
242 	}
243 
244 	is_zero_matrix = true;
245 	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
246 		if (matrix_volatile_state[i] != 0) {
247 			is_zero_matrix = false;
248 			break;
249 		}
250 	}
251 
252 
253 	if (is_zero_matrix) {
254 		/*
255 		 * All keys have been released. Enable only the KDI
256 		 * interrupt for future key presses (clear the KDI
257 		 * status bit and its sync chain before that).
258 		 */
259 		reg_val = readw(keypad->mmio_base + KPSR);
260 		reg_val |= KBD_STAT_KPKD | KBD_STAT_KDSC;
261 		writew(reg_val, keypad->mmio_base + KPSR);
262 
263 		reg_val = readw(keypad->mmio_base + KPSR);
264 		reg_val |= KBD_STAT_KDIE;
265 		reg_val &= ~KBD_STAT_KRIE;
266 		writew(reg_val, keypad->mmio_base + KPSR);
267 	} else {
268 		/*
269 		 * Some keys are still pressed. Schedule a rescan in
270 		 * attempt to detect multiple key presses and enable
271 		 * the KRI interrupt to react quickly to key release
272 		 * event.
273 		 */
274 		mod_timer(&keypad->check_matrix_timer,
275 			  jiffies + msecs_to_jiffies(60));
276 
277 		reg_val = readw(keypad->mmio_base + KPSR);
278 		reg_val |= KBD_STAT_KPKR | KBD_STAT_KRSS;
279 		writew(reg_val, keypad->mmio_base + KPSR);
280 
281 		reg_val = readw(keypad->mmio_base + KPSR);
282 		reg_val |= KBD_STAT_KRIE;
283 		reg_val &= ~KBD_STAT_KDIE;
284 		writew(reg_val, keypad->mmio_base + KPSR);
285 	}
286 }
287 
288 static irqreturn_t imx_keypad_irq_handler(int irq, void *dev_id)
289 {
290 	struct imx_keypad *keypad = dev_id;
291 	unsigned short reg_val;
292 
293 	reg_val = readw(keypad->mmio_base + KPSR);
294 
295 	/* Disable both interrupt types */
296 	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
297 	/* Clear interrupts status bits */
298 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
299 	writew(reg_val, keypad->mmio_base + KPSR);
300 
301 	if (keypad->enabled) {
302 		/* The matrix is supposed to be changed */
303 		keypad->stable_count = 0;
304 
305 		/* Schedule the scanning procedure near in the future */
306 		mod_timer(&keypad->check_matrix_timer,
307 			  jiffies + msecs_to_jiffies(2));
308 	}
309 
310 	return IRQ_HANDLED;
311 }
312 
313 static void imx_keypad_config(struct imx_keypad *keypad)
314 {
315 	unsigned short reg_val;
316 
317 	/*
318 	 * Include enabled rows in interrupt generation (KPCR[7:0])
319 	 * Configure keypad columns as open-drain (KPCR[15:8])
320 	 */
321 	reg_val = readw(keypad->mmio_base + KPCR);
322 	reg_val |= keypad->rows_en_mask & 0xff;		/* rows */
323 	reg_val |= (keypad->cols_en_mask & 0xff) << 8;	/* cols */
324 	writew(reg_val, keypad->mmio_base + KPCR);
325 
326 	/* Write 0's to KPDR[15:8] (Colums) */
327 	reg_val = readw(keypad->mmio_base + KPDR);
328 	reg_val &= 0x00ff;
329 	writew(reg_val, keypad->mmio_base + KPDR);
330 
331 	/* Configure columns as output, rows as input (KDDR[15:0]) */
332 	writew(0xff00, keypad->mmio_base + KDDR);
333 
334 	/*
335 	 * Clear Key Depress and Key Release status bit.
336 	 * Clear both synchronizer chain.
337 	 */
338 	reg_val = readw(keypad->mmio_base + KPSR);
339 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD |
340 		   KBD_STAT_KDSC | KBD_STAT_KRSS;
341 	writew(reg_val, keypad->mmio_base + KPSR);
342 
343 	/* Enable KDI and disable KRI (avoid false release events). */
344 	reg_val |= KBD_STAT_KDIE;
345 	reg_val &= ~KBD_STAT_KRIE;
346 	writew(reg_val, keypad->mmio_base + KPSR);
347 }
348 
349 static void imx_keypad_inhibit(struct imx_keypad *keypad)
350 {
351 	unsigned short reg_val;
352 
353 	/* Inhibit KDI and KRI interrupts. */
354 	reg_val = readw(keypad->mmio_base + KPSR);
355 	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
356 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
357 	writew(reg_val, keypad->mmio_base + KPSR);
358 
359 	/* Colums as open drain and disable all rows */
360 	reg_val = (keypad->cols_en_mask & 0xff) << 8;
361 	writew(reg_val, keypad->mmio_base + KPCR);
362 }
363 
364 static void imx_keypad_close(struct input_dev *dev)
365 {
366 	struct imx_keypad *keypad = input_get_drvdata(dev);
367 
368 	dev_dbg(&dev->dev, ">%s\n", __func__);
369 
370 	/* Mark keypad as being inactive */
371 	keypad->enabled = false;
372 	synchronize_irq(keypad->irq);
373 	del_timer_sync(&keypad->check_matrix_timer);
374 
375 	imx_keypad_inhibit(keypad);
376 
377 	/* Disable clock unit */
378 	clk_disable_unprepare(keypad->clk);
379 }
380 
381 static int imx_keypad_open(struct input_dev *dev)
382 {
383 	struct imx_keypad *keypad = input_get_drvdata(dev);
384 	int error;
385 
386 	dev_dbg(&dev->dev, ">%s\n", __func__);
387 
388 	/* Enable the kpp clock */
389 	error = clk_prepare_enable(keypad->clk);
390 	if (error)
391 		return error;
392 
393 	/* We became active from now */
394 	keypad->enabled = true;
395 
396 	imx_keypad_config(keypad);
397 
398 	/* Sanity control, not all the rows must be actived now. */
399 	if ((readw(keypad->mmio_base + KPDR) & keypad->rows_en_mask) == 0) {
400 		dev_err(&dev->dev,
401 			"too many keys pressed, control pins initialisation\n");
402 		goto open_err;
403 	}
404 
405 	return 0;
406 
407 open_err:
408 	imx_keypad_close(dev);
409 	return -EIO;
410 }
411 
412 static const struct of_device_id imx_keypad_of_match[] = {
413 	{ .compatible = "fsl,imx21-kpp", },
414 	{ /* sentinel */ }
415 };
416 MODULE_DEVICE_TABLE(of, imx_keypad_of_match);
417 
418 static int imx_keypad_probe(struct platform_device *pdev)
419 {
420 	struct imx_keypad *keypad;
421 	struct input_dev *input_dev;
422 	int irq, error, i, row, col;
423 
424 	irq = platform_get_irq(pdev, 0);
425 	if (irq < 0)
426 		return irq;
427 
428 	input_dev = devm_input_allocate_device(&pdev->dev);
429 	if (!input_dev) {
430 		dev_err(&pdev->dev, "failed to allocate the input device\n");
431 		return -ENOMEM;
432 	}
433 
434 	keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
435 	if (!keypad) {
436 		dev_err(&pdev->dev, "not enough memory for driver data\n");
437 		return -ENOMEM;
438 	}
439 
440 	keypad->input_dev = input_dev;
441 	keypad->irq = irq;
442 	keypad->stable_count = 0;
443 
444 	timer_setup(&keypad->check_matrix_timer,
445 		    imx_keypad_check_for_events, 0);
446 
447 	keypad->mmio_base = devm_platform_ioremap_resource(pdev, 0);
448 	if (IS_ERR(keypad->mmio_base))
449 		return PTR_ERR(keypad->mmio_base);
450 
451 	keypad->clk = devm_clk_get(&pdev->dev, NULL);
452 	if (IS_ERR(keypad->clk)) {
453 		dev_err(&pdev->dev, "failed to get keypad clock\n");
454 		return PTR_ERR(keypad->clk);
455 	}
456 
457 	/* Init the Input device */
458 	input_dev->name = pdev->name;
459 	input_dev->id.bustype = BUS_HOST;
460 	input_dev->dev.parent = &pdev->dev;
461 	input_dev->open = imx_keypad_open;
462 	input_dev->close = imx_keypad_close;
463 
464 	error = matrix_keypad_build_keymap(NULL, NULL,
465 					   MAX_MATRIX_KEY_ROWS,
466 					   MAX_MATRIX_KEY_COLS,
467 					   keypad->keycodes, input_dev);
468 	if (error) {
469 		dev_err(&pdev->dev, "failed to build keymap\n");
470 		return error;
471 	}
472 
473 	/* Search for rows and cols enabled */
474 	for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
475 		for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
476 			i = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
477 			if (keypad->keycodes[i] != KEY_RESERVED) {
478 				keypad->rows_en_mask |= 1 << row;
479 				keypad->cols_en_mask |= 1 << col;
480 			}
481 		}
482 	}
483 	dev_dbg(&pdev->dev, "enabled rows mask: %x\n", keypad->rows_en_mask);
484 	dev_dbg(&pdev->dev, "enabled cols mask: %x\n", keypad->cols_en_mask);
485 
486 	__set_bit(EV_REP, input_dev->evbit);
487 	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
488 	input_set_drvdata(input_dev, keypad);
489 
490 	/* Ensure that the keypad will stay dormant until opened */
491 	error = clk_prepare_enable(keypad->clk);
492 	if (error)
493 		return error;
494 	imx_keypad_inhibit(keypad);
495 	clk_disable_unprepare(keypad->clk);
496 
497 	error = devm_request_irq(&pdev->dev, irq, imx_keypad_irq_handler, 0,
498 			    pdev->name, keypad);
499 	if (error) {
500 		dev_err(&pdev->dev, "failed to request IRQ\n");
501 		return error;
502 	}
503 
504 	/* Register the input device */
505 	error = input_register_device(input_dev);
506 	if (error) {
507 		dev_err(&pdev->dev, "failed to register input device\n");
508 		return error;
509 	}
510 
511 	platform_set_drvdata(pdev, keypad);
512 	device_init_wakeup(&pdev->dev, 1);
513 
514 	return 0;
515 }
516 
517 static int __maybe_unused imx_kbd_noirq_suspend(struct device *dev)
518 {
519 	struct platform_device *pdev = to_platform_device(dev);
520 	struct imx_keypad *kbd = platform_get_drvdata(pdev);
521 	struct input_dev *input_dev = kbd->input_dev;
522 	unsigned short reg_val = readw(kbd->mmio_base + KPSR);
523 
524 	/* imx kbd can wake up system even clock is disabled */
525 	mutex_lock(&input_dev->mutex);
526 
527 	if (input_device_enabled(input_dev))
528 		clk_disable_unprepare(kbd->clk);
529 
530 	mutex_unlock(&input_dev->mutex);
531 
532 	if (device_may_wakeup(&pdev->dev)) {
533 		if (reg_val & KBD_STAT_KPKD)
534 			reg_val |= KBD_STAT_KRIE;
535 		if (reg_val & KBD_STAT_KPKR)
536 			reg_val |= KBD_STAT_KDIE;
537 		writew(reg_val, kbd->mmio_base + KPSR);
538 
539 		enable_irq_wake(kbd->irq);
540 	}
541 
542 	return 0;
543 }
544 
545 static int __maybe_unused imx_kbd_noirq_resume(struct device *dev)
546 {
547 	struct platform_device *pdev = to_platform_device(dev);
548 	struct imx_keypad *kbd = platform_get_drvdata(pdev);
549 	struct input_dev *input_dev = kbd->input_dev;
550 	int ret = 0;
551 
552 	if (device_may_wakeup(&pdev->dev))
553 		disable_irq_wake(kbd->irq);
554 
555 	mutex_lock(&input_dev->mutex);
556 
557 	if (input_device_enabled(input_dev)) {
558 		ret = clk_prepare_enable(kbd->clk);
559 		if (ret)
560 			goto err_clk;
561 	}
562 
563 err_clk:
564 	mutex_unlock(&input_dev->mutex);
565 
566 	return ret;
567 }
568 
569 static const struct dev_pm_ops imx_kbd_pm_ops = {
570 	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx_kbd_noirq_suspend, imx_kbd_noirq_resume)
571 };
572 
573 static struct platform_driver imx_keypad_driver = {
574 	.driver		= {
575 		.name	= "imx-keypad",
576 		.pm	= &imx_kbd_pm_ops,
577 		.of_match_table = imx_keypad_of_match,
578 	},
579 	.probe		= imx_keypad_probe,
580 };
581 module_platform_driver(imx_keypad_driver);
582 
583 MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
584 MODULE_DESCRIPTION("IMX Keypad Port Driver");
585 MODULE_LICENSE("GPL v2");
586 MODULE_ALIAS("platform:imx-keypad");
587