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/matrix_keypad.h>
11 #include <linux/interrupt.h>
12 #include <linux/io.h>
13 #include <linux/jiffies.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/slab.h>
19 #include <linux/timer.h>
20 
21 /*
22  * Keypad Controller registers (halfword)
23  */
24 #define KPCR		0x00 /* Keypad Control Register */
25 
26 #define KPSR		0x02 /* Keypad Status Register */
27 #define KBD_STAT_KPKD	(0x1 << 0) /* Key Press Interrupt Status bit (w1c) */
28 #define KBD_STAT_KPKR	(0x1 << 1) /* Key Release Interrupt Status bit (w1c) */
29 #define KBD_STAT_KDSC	(0x1 << 2) /* Key Depress Synch Chain Status bit (w1c)*/
30 #define KBD_STAT_KRSS	(0x1 << 3) /* Key Release Synch Status bit (w1c)*/
31 #define KBD_STAT_KDIE	(0x1 << 8) /* Key Depress Interrupt Enable Status bit */
32 #define KBD_STAT_KRIE	(0x1 << 9) /* Key Release Interrupt Enable */
33 #define KBD_STAT_KPPEN	(0x1 << 10) /* Keypad Clock Enable */
34 
35 #define KDDR		0x04 /* Keypad Data Direction Register */
36 #define KPDR		0x06 /* Keypad Data Register */
37 
38 #define MAX_MATRIX_KEY_ROWS	8
39 #define MAX_MATRIX_KEY_COLS	8
40 #define MATRIX_ROW_SHIFT	3
41 
42 #define MAX_MATRIX_KEY_NUM	(MAX_MATRIX_KEY_ROWS * MAX_MATRIX_KEY_COLS)
43 
44 struct imx_keypad {
45 
46 	struct clk *clk;
47 	struct input_dev *input_dev;
48 	void __iomem *mmio_base;
49 
50 	int			irq;
51 	struct timer_list	check_matrix_timer;
52 
53 	/*
54 	 * The matrix is stable only if no changes are detected after
55 	 * IMX_KEYPAD_SCANS_FOR_STABILITY scans
56 	 */
57 #define IMX_KEYPAD_SCANS_FOR_STABILITY 3
58 	int			stable_count;
59 
60 	bool			enabled;
61 
62 	/* Masks for enabled rows/cols */
63 	unsigned short		rows_en_mask;
64 	unsigned short		cols_en_mask;
65 
66 	unsigned short		keycodes[MAX_MATRIX_KEY_NUM];
67 
68 	/*
69 	 * Matrix states:
70 	 * -stable: achieved after a complete debounce process.
71 	 * -unstable: used in the debouncing process.
72 	 */
73 	unsigned short		matrix_stable_state[MAX_MATRIX_KEY_COLS];
74 	unsigned short		matrix_unstable_state[MAX_MATRIX_KEY_COLS];
75 };
76 
77 /* Scan the matrix and return the new state in *matrix_volatile_state. */
78 static void imx_keypad_scan_matrix(struct imx_keypad *keypad,
79 				  unsigned short *matrix_volatile_state)
80 {
81 	int col;
82 	unsigned short reg_val;
83 
84 	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
85 		if ((keypad->cols_en_mask & (1 << col)) == 0)
86 			continue;
87 		/*
88 		 * Discharge keypad capacitance:
89 		 * 2. write 1s on column data.
90 		 * 3. configure columns as totem-pole to discharge capacitance.
91 		 * 4. configure columns as open-drain.
92 		 */
93 		reg_val = readw(keypad->mmio_base + KPDR);
94 		reg_val |= 0xff00;
95 		writew(reg_val, keypad->mmio_base + KPDR);
96 
97 		reg_val = readw(keypad->mmio_base + KPCR);
98 		reg_val &= ~((keypad->cols_en_mask & 0xff) << 8);
99 		writew(reg_val, keypad->mmio_base + KPCR);
100 
101 		udelay(2);
102 
103 		reg_val = readw(keypad->mmio_base + KPCR);
104 		reg_val |= (keypad->cols_en_mask & 0xff) << 8;
105 		writew(reg_val, keypad->mmio_base + KPCR);
106 
107 		/*
108 		 * 5. Write a single column to 0, others to 1.
109 		 * 6. Sample row inputs and save data.
110 		 * 7. Repeat steps 2 - 6 for remaining columns.
111 		 */
112 		reg_val = readw(keypad->mmio_base + KPDR);
113 		reg_val &= ~(1 << (8 + col));
114 		writew(reg_val, keypad->mmio_base + KPDR);
115 
116 		/*
117 		 * Delay added to avoid propagating the 0 from column to row
118 		 * when scanning.
119 		 */
120 		udelay(5);
121 
122 		/*
123 		 * 1s in matrix_volatile_state[col] means key pressures
124 		 * throw data from non enabled rows.
125 		 */
126 		reg_val = readw(keypad->mmio_base + KPDR);
127 		matrix_volatile_state[col] = (~reg_val) & keypad->rows_en_mask;
128 	}
129 
130 	/*
131 	 * Return in standby mode:
132 	 * 9. write 0s to columns
133 	 */
134 	reg_val = readw(keypad->mmio_base + KPDR);
135 	reg_val &= 0x00ff;
136 	writew(reg_val, keypad->mmio_base + KPDR);
137 }
138 
139 /*
140  * Compare the new matrix state (volatile) with the stable one stored in
141  * keypad->matrix_stable_state and fire events if changes are detected.
142  */
143 static void imx_keypad_fire_events(struct imx_keypad *keypad,
144 				   unsigned short *matrix_volatile_state)
145 {
146 	struct input_dev *input_dev = keypad->input_dev;
147 	int row, col;
148 
149 	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
150 		unsigned short bits_changed;
151 		int code;
152 
153 		if ((keypad->cols_en_mask & (1 << col)) == 0)
154 			continue; /* Column is not enabled */
155 
156 		bits_changed = keypad->matrix_stable_state[col] ^
157 						matrix_volatile_state[col];
158 
159 		if (bits_changed == 0)
160 			continue; /* Column does not contain changes */
161 
162 		for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
163 			if ((keypad->rows_en_mask & (1 << row)) == 0)
164 				continue; /* Row is not enabled */
165 			if ((bits_changed & (1 << row)) == 0)
166 				continue; /* Row does not contain changes */
167 
168 			code = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
169 			input_event(input_dev, EV_MSC, MSC_SCAN, code);
170 			input_report_key(input_dev, keypad->keycodes[code],
171 				matrix_volatile_state[col] & (1 << row));
172 			dev_dbg(&input_dev->dev, "Event code: %d, val: %d",
173 				keypad->keycodes[code],
174 				matrix_volatile_state[col] & (1 << row));
175 		}
176 	}
177 	input_sync(input_dev);
178 }
179 
180 /*
181  * imx_keypad_check_for_events is the timer handler.
182  */
183 static void imx_keypad_check_for_events(struct timer_list *t)
184 {
185 	struct imx_keypad *keypad = from_timer(keypad, t, check_matrix_timer);
186 	unsigned short matrix_volatile_state[MAX_MATRIX_KEY_COLS];
187 	unsigned short reg_val;
188 	bool state_changed, is_zero_matrix;
189 	int i;
190 
191 	memset(matrix_volatile_state, 0, sizeof(matrix_volatile_state));
192 
193 	imx_keypad_scan_matrix(keypad, matrix_volatile_state);
194 
195 	state_changed = false;
196 	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
197 		if ((keypad->cols_en_mask & (1 << i)) == 0)
198 			continue;
199 
200 		if (keypad->matrix_unstable_state[i] ^ matrix_volatile_state[i]) {
201 			state_changed = true;
202 			break;
203 		}
204 	}
205 
206 	/*
207 	 * If the matrix state is changed from the previous scan
208 	 *   (Re)Begin the debouncing process, saving the new state in
209 	 *    keypad->matrix_unstable_state.
210 	 * else
211 	 *   Increase the count of number of scans with a stable state.
212 	 */
213 	if (state_changed) {
214 		memcpy(keypad->matrix_unstable_state, matrix_volatile_state,
215 			sizeof(matrix_volatile_state));
216 		keypad->stable_count = 0;
217 	} else
218 		keypad->stable_count++;
219 
220 	/*
221 	 * If the matrix is not as stable as we want reschedule scan
222 	 * in the near future.
223 	 */
224 	if (keypad->stable_count < IMX_KEYPAD_SCANS_FOR_STABILITY) {
225 		mod_timer(&keypad->check_matrix_timer,
226 			  jiffies + msecs_to_jiffies(10));
227 		return;
228 	}
229 
230 	/*
231 	 * If the matrix state is stable, fire the events and save the new
232 	 * stable state. Note, if the matrix is kept stable for longer
233 	 * (keypad->stable_count > IMX_KEYPAD_SCANS_FOR_STABILITY) all
234 	 * events have already been generated.
235 	 */
236 	if (keypad->stable_count == IMX_KEYPAD_SCANS_FOR_STABILITY) {
237 		imx_keypad_fire_events(keypad, matrix_volatile_state);
238 
239 		memcpy(keypad->matrix_stable_state, matrix_volatile_state,
240 			sizeof(matrix_volatile_state));
241 	}
242 
243 	is_zero_matrix = true;
244 	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
245 		if (matrix_volatile_state[i] != 0) {
246 			is_zero_matrix = false;
247 			break;
248 		}
249 	}
250 
251 
252 	if (is_zero_matrix) {
253 		/*
254 		 * All keys have been released. Enable only the KDI
255 		 * interrupt for future key presses (clear the KDI
256 		 * status bit and its sync chain before that).
257 		 */
258 		reg_val = readw(keypad->mmio_base + KPSR);
259 		reg_val |= KBD_STAT_KPKD | KBD_STAT_KDSC;
260 		writew(reg_val, keypad->mmio_base + KPSR);
261 
262 		reg_val = readw(keypad->mmio_base + KPSR);
263 		reg_val |= KBD_STAT_KDIE;
264 		reg_val &= ~KBD_STAT_KRIE;
265 		writew(reg_val, keypad->mmio_base + KPSR);
266 	} else {
267 		/*
268 		 * Some keys are still pressed. Schedule a rescan in
269 		 * attempt to detect multiple key presses and enable
270 		 * the KRI interrupt to react quickly to key release
271 		 * event.
272 		 */
273 		mod_timer(&keypad->check_matrix_timer,
274 			  jiffies + msecs_to_jiffies(60));
275 
276 		reg_val = readw(keypad->mmio_base + KPSR);
277 		reg_val |= KBD_STAT_KPKR | KBD_STAT_KRSS;
278 		writew(reg_val, keypad->mmio_base + KPSR);
279 
280 		reg_val = readw(keypad->mmio_base + KPSR);
281 		reg_val |= KBD_STAT_KRIE;
282 		reg_val &= ~KBD_STAT_KDIE;
283 		writew(reg_val, keypad->mmio_base + KPSR);
284 	}
285 }
286 
287 static irqreturn_t imx_keypad_irq_handler(int irq, void *dev_id)
288 {
289 	struct imx_keypad *keypad = dev_id;
290 	unsigned short reg_val;
291 
292 	reg_val = readw(keypad->mmio_base + KPSR);
293 
294 	/* Disable both interrupt types */
295 	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
296 	/* Clear interrupts status bits */
297 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
298 	writew(reg_val, keypad->mmio_base + KPSR);
299 
300 	if (keypad->enabled) {
301 		/* The matrix is supposed to be changed */
302 		keypad->stable_count = 0;
303 
304 		/* Schedule the scanning procedure near in the future */
305 		mod_timer(&keypad->check_matrix_timer,
306 			  jiffies + msecs_to_jiffies(2));
307 	}
308 
309 	return IRQ_HANDLED;
310 }
311 
312 static void imx_keypad_config(struct imx_keypad *keypad)
313 {
314 	unsigned short reg_val;
315 
316 	/*
317 	 * Include enabled rows in interrupt generation (KPCR[7:0])
318 	 * Configure keypad columns as open-drain (KPCR[15:8])
319 	 */
320 	reg_val = readw(keypad->mmio_base + KPCR);
321 	reg_val |= keypad->rows_en_mask & 0xff;		/* rows */
322 	reg_val |= (keypad->cols_en_mask & 0xff) << 8;	/* cols */
323 	writew(reg_val, keypad->mmio_base + KPCR);
324 
325 	/* Write 0's to KPDR[15:8] (Colums) */
326 	reg_val = readw(keypad->mmio_base + KPDR);
327 	reg_val &= 0x00ff;
328 	writew(reg_val, keypad->mmio_base + KPDR);
329 
330 	/* Configure columns as output, rows as input (KDDR[15:0]) */
331 	writew(0xff00, keypad->mmio_base + KDDR);
332 
333 	/*
334 	 * Clear Key Depress and Key Release status bit.
335 	 * Clear both synchronizer chain.
336 	 */
337 	reg_val = readw(keypad->mmio_base + KPSR);
338 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD |
339 		   KBD_STAT_KDSC | KBD_STAT_KRSS;
340 	writew(reg_val, keypad->mmio_base + KPSR);
341 
342 	/* Enable KDI and disable KRI (avoid false release events). */
343 	reg_val |= KBD_STAT_KDIE;
344 	reg_val &= ~KBD_STAT_KRIE;
345 	writew(reg_val, keypad->mmio_base + KPSR);
346 }
347 
348 static void imx_keypad_inhibit(struct imx_keypad *keypad)
349 {
350 	unsigned short reg_val;
351 
352 	/* Inhibit KDI and KRI interrupts. */
353 	reg_val = readw(keypad->mmio_base + KPSR);
354 	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
355 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
356 	writew(reg_val, keypad->mmio_base + KPSR);
357 
358 	/* Colums as open drain and disable all rows */
359 	reg_val = (keypad->cols_en_mask & 0xff) << 8;
360 	writew(reg_val, keypad->mmio_base + KPCR);
361 }
362 
363 static void imx_keypad_close(struct input_dev *dev)
364 {
365 	struct imx_keypad *keypad = input_get_drvdata(dev);
366 
367 	dev_dbg(&dev->dev, ">%s\n", __func__);
368 
369 	/* Mark keypad as being inactive */
370 	keypad->enabled = false;
371 	synchronize_irq(keypad->irq);
372 	del_timer_sync(&keypad->check_matrix_timer);
373 
374 	imx_keypad_inhibit(keypad);
375 
376 	/* Disable clock unit */
377 	clk_disable_unprepare(keypad->clk);
378 }
379 
380 static int imx_keypad_open(struct input_dev *dev)
381 {
382 	struct imx_keypad *keypad = input_get_drvdata(dev);
383 	int error;
384 
385 	dev_dbg(&dev->dev, ">%s\n", __func__);
386 
387 	/* Enable the kpp clock */
388 	error = clk_prepare_enable(keypad->clk);
389 	if (error)
390 		return error;
391 
392 	/* We became active from now */
393 	keypad->enabled = true;
394 
395 	imx_keypad_config(keypad);
396 
397 	/* Sanity control, not all the rows must be actived now. */
398 	if ((readw(keypad->mmio_base + KPDR) & keypad->rows_en_mask) == 0) {
399 		dev_err(&dev->dev,
400 			"too many keys pressed, control pins initialisation\n");
401 		goto open_err;
402 	}
403 
404 	return 0;
405 
406 open_err:
407 	imx_keypad_close(dev);
408 	return -EIO;
409 }
410 
411 #ifdef CONFIG_OF
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 #endif
418 
419 static int imx_keypad_probe(struct platform_device *pdev)
420 {
421 	const struct matrix_keymap_data *keymap_data =
422 			dev_get_platdata(&pdev->dev);
423 	struct imx_keypad *keypad;
424 	struct input_dev *input_dev;
425 	struct resource *res;
426 	int irq, error, i, row, col;
427 
428 	if (!keymap_data && !pdev->dev.of_node) {
429 		dev_err(&pdev->dev, "no keymap defined\n");
430 		return -EINVAL;
431 	}
432 
433 	irq = platform_get_irq(pdev, 0);
434 	if (irq < 0) {
435 		dev_err(&pdev->dev, "no irq defined in platform data\n");
436 		return irq;
437 	}
438 
439 	input_dev = devm_input_allocate_device(&pdev->dev);
440 	if (!input_dev) {
441 		dev_err(&pdev->dev, "failed to allocate the input device\n");
442 		return -ENOMEM;
443 	}
444 
445 	keypad = devm_kzalloc(&pdev->dev, sizeof(*keypad), GFP_KERNEL);
446 	if (!keypad) {
447 		dev_err(&pdev->dev, "not enough memory for driver data\n");
448 		return -ENOMEM;
449 	}
450 
451 	keypad->input_dev = input_dev;
452 	keypad->irq = irq;
453 	keypad->stable_count = 0;
454 
455 	timer_setup(&keypad->check_matrix_timer,
456 		    imx_keypad_check_for_events, 0);
457 
458 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
459 	keypad->mmio_base = devm_ioremap_resource(&pdev->dev, res);
460 	if (IS_ERR(keypad->mmio_base))
461 		return PTR_ERR(keypad->mmio_base);
462 
463 	keypad->clk = devm_clk_get(&pdev->dev, NULL);
464 	if (IS_ERR(keypad->clk)) {
465 		dev_err(&pdev->dev, "failed to get keypad clock\n");
466 		return PTR_ERR(keypad->clk);
467 	}
468 
469 	/* Init the Input device */
470 	input_dev->name = pdev->name;
471 	input_dev->id.bustype = BUS_HOST;
472 	input_dev->dev.parent = &pdev->dev;
473 	input_dev->open = imx_keypad_open;
474 	input_dev->close = imx_keypad_close;
475 
476 	error = matrix_keypad_build_keymap(keymap_data, NULL,
477 					   MAX_MATRIX_KEY_ROWS,
478 					   MAX_MATRIX_KEY_COLS,
479 					   keypad->keycodes, input_dev);
480 	if (error) {
481 		dev_err(&pdev->dev, "failed to build keymap\n");
482 		return error;
483 	}
484 
485 	/* Search for rows and cols enabled */
486 	for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
487 		for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
488 			i = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
489 			if (keypad->keycodes[i] != KEY_RESERVED) {
490 				keypad->rows_en_mask |= 1 << row;
491 				keypad->cols_en_mask |= 1 << col;
492 			}
493 		}
494 	}
495 	dev_dbg(&pdev->dev, "enabled rows mask: %x\n", keypad->rows_en_mask);
496 	dev_dbg(&pdev->dev, "enabled cols mask: %x\n", keypad->cols_en_mask);
497 
498 	__set_bit(EV_REP, input_dev->evbit);
499 	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
500 	input_set_drvdata(input_dev, keypad);
501 
502 	/* Ensure that the keypad will stay dormant until opened */
503 	error = clk_prepare_enable(keypad->clk);
504 	if (error)
505 		return error;
506 	imx_keypad_inhibit(keypad);
507 	clk_disable_unprepare(keypad->clk);
508 
509 	error = devm_request_irq(&pdev->dev, irq, imx_keypad_irq_handler, 0,
510 			    pdev->name, keypad);
511 	if (error) {
512 		dev_err(&pdev->dev, "failed to request IRQ\n");
513 		return error;
514 	}
515 
516 	/* Register the input device */
517 	error = input_register_device(input_dev);
518 	if (error) {
519 		dev_err(&pdev->dev, "failed to register input device\n");
520 		return error;
521 	}
522 
523 	platform_set_drvdata(pdev, keypad);
524 	device_init_wakeup(&pdev->dev, 1);
525 
526 	return 0;
527 }
528 
529 static int __maybe_unused imx_kbd_suspend(struct device *dev)
530 {
531 	struct platform_device *pdev = to_platform_device(dev);
532 	struct imx_keypad *kbd = platform_get_drvdata(pdev);
533 	struct input_dev *input_dev = kbd->input_dev;
534 
535 	/* imx kbd can wake up system even clock is disabled */
536 	mutex_lock(&input_dev->mutex);
537 
538 	if (input_dev->users)
539 		clk_disable_unprepare(kbd->clk);
540 
541 	mutex_unlock(&input_dev->mutex);
542 
543 	if (device_may_wakeup(&pdev->dev))
544 		enable_irq_wake(kbd->irq);
545 
546 	return 0;
547 }
548 
549 static int __maybe_unused imx_kbd_resume(struct device *dev)
550 {
551 	struct platform_device *pdev = to_platform_device(dev);
552 	struct imx_keypad *kbd = platform_get_drvdata(pdev);
553 	struct input_dev *input_dev = kbd->input_dev;
554 	int ret = 0;
555 
556 	if (device_may_wakeup(&pdev->dev))
557 		disable_irq_wake(kbd->irq);
558 
559 	mutex_lock(&input_dev->mutex);
560 
561 	if (input_dev->users) {
562 		ret = clk_prepare_enable(kbd->clk);
563 		if (ret)
564 			goto err_clk;
565 	}
566 
567 err_clk:
568 	mutex_unlock(&input_dev->mutex);
569 
570 	return ret;
571 }
572 
573 static SIMPLE_DEV_PM_OPS(imx_kbd_pm_ops, imx_kbd_suspend, imx_kbd_resume);
574 
575 static struct platform_driver imx_keypad_driver = {
576 	.driver		= {
577 		.name	= "imx-keypad",
578 		.pm	= &imx_kbd_pm_ops,
579 		.of_match_table = of_match_ptr(imx_keypad_of_match),
580 	},
581 	.probe		= imx_keypad_probe,
582 };
583 module_platform_driver(imx_keypad_driver);
584 
585 MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
586 MODULE_DESCRIPTION("IMX Keypad Port Driver");
587 MODULE_LICENSE("GPL v2");
588 MODULE_ALIAS("platform:imx-keypad");
589