1 /*
2  * Driver for the IMX keypad port.
3  * Copyright (C) 2009 Alberto Panizzo <maramaopercheseimorto@gmail.com>
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of the GNU General Public License version 2 as
7  * published by the Free Software Foundation.
8  *
9  * <<Power management needs to be implemented>>.
10  */
11 
12 #include <linux/clk.h>
13 #include <linux/delay.h>
14 #include <linux/device.h>
15 #include <linux/err.h>
16 #include <linux/input/matrix_keypad.h>
17 #include <linux/interrupt.h>
18 #include <linux/io.h>
19 #include <linux/jiffies.h>
20 #include <linux/kernel.h>
21 #include <linux/module.h>
22 #include <linux/of.h>
23 #include <linux/platform_device.h>
24 #include <linux/slab.h>
25 #include <linux/timer.h>
26 
27 /*
28  * Keypad Controller registers (halfword)
29  */
30 #define KPCR		0x00 /* Keypad Control Register */
31 
32 #define KPSR		0x02 /* Keypad Status Register */
33 #define KBD_STAT_KPKD	(0x1 << 0) /* Key Press Interrupt Status bit (w1c) */
34 #define KBD_STAT_KPKR	(0x1 << 1) /* Key Release Interrupt Status bit (w1c) */
35 #define KBD_STAT_KDSC	(0x1 << 2) /* Key Depress Synch Chain Status bit (w1c)*/
36 #define KBD_STAT_KRSS	(0x1 << 3) /* Key Release Synch Status bit (w1c)*/
37 #define KBD_STAT_KDIE	(0x1 << 8) /* Key Depress Interrupt Enable Status bit */
38 #define KBD_STAT_KRIE	(0x1 << 9) /* Key Release Interrupt Enable */
39 #define KBD_STAT_KPPEN	(0x1 << 10) /* Keypad Clock Enable */
40 
41 #define KDDR		0x04 /* Keypad Data Direction Register */
42 #define KPDR		0x06 /* Keypad Data Register */
43 
44 #define MAX_MATRIX_KEY_ROWS	8
45 #define MAX_MATRIX_KEY_COLS	8
46 #define MATRIX_ROW_SHIFT	3
47 
48 #define MAX_MATRIX_KEY_NUM	(MAX_MATRIX_KEY_ROWS * MAX_MATRIX_KEY_COLS)
49 
50 struct imx_keypad {
51 
52 	struct clk *clk;
53 	struct input_dev *input_dev;
54 	void __iomem *mmio_base;
55 
56 	int			irq;
57 	struct timer_list	check_matrix_timer;
58 
59 	/*
60 	 * The matrix is stable only if no changes are detected after
61 	 * IMX_KEYPAD_SCANS_FOR_STABILITY scans
62 	 */
63 #define IMX_KEYPAD_SCANS_FOR_STABILITY 3
64 	int			stable_count;
65 
66 	bool			enabled;
67 
68 	/* Masks for enabled rows/cols */
69 	unsigned short		rows_en_mask;
70 	unsigned short		cols_en_mask;
71 
72 	unsigned short		keycodes[MAX_MATRIX_KEY_NUM];
73 
74 	/*
75 	 * Matrix states:
76 	 * -stable: achieved after a complete debounce process.
77 	 * -unstable: used in the debouncing process.
78 	 */
79 	unsigned short		matrix_stable_state[MAX_MATRIX_KEY_COLS];
80 	unsigned short		matrix_unstable_state[MAX_MATRIX_KEY_COLS];
81 };
82 
83 /* Scan the matrix and return the new state in *matrix_volatile_state. */
84 static void imx_keypad_scan_matrix(struct imx_keypad *keypad,
85 				  unsigned short *matrix_volatile_state)
86 {
87 	int col;
88 	unsigned short reg_val;
89 
90 	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
91 		if ((keypad->cols_en_mask & (1 << col)) == 0)
92 			continue;
93 		/*
94 		 * Discharge keypad capacitance:
95 		 * 2. write 1s on column data.
96 		 * 3. configure columns as totem-pole to discharge capacitance.
97 		 * 4. configure columns as open-drain.
98 		 */
99 		reg_val = readw(keypad->mmio_base + KPDR);
100 		reg_val |= 0xff00;
101 		writew(reg_val, keypad->mmio_base + KPDR);
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 		udelay(2);
108 
109 		reg_val = readw(keypad->mmio_base + KPCR);
110 		reg_val |= (keypad->cols_en_mask & 0xff) << 8;
111 		writew(reg_val, keypad->mmio_base + KPCR);
112 
113 		/*
114 		 * 5. Write a single column to 0, others to 1.
115 		 * 6. Sample row inputs and save data.
116 		 * 7. Repeat steps 2 - 6 for remaining columns.
117 		 */
118 		reg_val = readw(keypad->mmio_base + KPDR);
119 		reg_val &= ~(1 << (8 + col));
120 		writew(reg_val, keypad->mmio_base + KPDR);
121 
122 		/*
123 		 * Delay added to avoid propagating the 0 from column to row
124 		 * when scanning.
125 		 */
126 		udelay(5);
127 
128 		/*
129 		 * 1s in matrix_volatile_state[col] means key pressures
130 		 * throw data from non enabled rows.
131 		 */
132 		reg_val = readw(keypad->mmio_base + KPDR);
133 		matrix_volatile_state[col] = (~reg_val) & keypad->rows_en_mask;
134 	}
135 
136 	/*
137 	 * Return in standby mode:
138 	 * 9. write 0s to columns
139 	 */
140 	reg_val = readw(keypad->mmio_base + KPDR);
141 	reg_val &= 0x00ff;
142 	writew(reg_val, keypad->mmio_base + KPDR);
143 }
144 
145 /*
146  * Compare the new matrix state (volatile) with the stable one stored in
147  * keypad->matrix_stable_state and fire events if changes are detected.
148  */
149 static void imx_keypad_fire_events(struct imx_keypad *keypad,
150 				   unsigned short *matrix_volatile_state)
151 {
152 	struct input_dev *input_dev = keypad->input_dev;
153 	int row, col;
154 
155 	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
156 		unsigned short bits_changed;
157 		int code;
158 
159 		if ((keypad->cols_en_mask & (1 << col)) == 0)
160 			continue; /* Column is not enabled */
161 
162 		bits_changed = keypad->matrix_stable_state[col] ^
163 						matrix_volatile_state[col];
164 
165 		if (bits_changed == 0)
166 			continue; /* Column does not contain changes */
167 
168 		for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
169 			if ((keypad->rows_en_mask & (1 << row)) == 0)
170 				continue; /* Row is not enabled */
171 			if ((bits_changed & (1 << row)) == 0)
172 				continue; /* Row does not contain changes */
173 
174 			code = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
175 			input_event(input_dev, EV_MSC, MSC_SCAN, code);
176 			input_report_key(input_dev, keypad->keycodes[code],
177 				matrix_volatile_state[col] & (1 << row));
178 			dev_dbg(&input_dev->dev, "Event code: %d, val: %d",
179 				keypad->keycodes[code],
180 				matrix_volatile_state[col] & (1 << row));
181 		}
182 	}
183 	input_sync(input_dev);
184 }
185 
186 /*
187  * imx_keypad_check_for_events is the timer handler.
188  */
189 static void imx_keypad_check_for_events(unsigned long data)
190 {
191 	struct imx_keypad *keypad = (struct imx_keypad *) data;
192 	unsigned short matrix_volatile_state[MAX_MATRIX_KEY_COLS];
193 	unsigned short reg_val;
194 	bool state_changed, is_zero_matrix;
195 	int i;
196 
197 	memset(matrix_volatile_state, 0, sizeof(matrix_volatile_state));
198 
199 	imx_keypad_scan_matrix(keypad, matrix_volatile_state);
200 
201 	state_changed = false;
202 	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
203 		if ((keypad->cols_en_mask & (1 << i)) == 0)
204 			continue;
205 
206 		if (keypad->matrix_unstable_state[i] ^ matrix_volatile_state[i]) {
207 			state_changed = true;
208 			break;
209 		}
210 	}
211 
212 	/*
213 	 * If the matrix state is changed from the previous scan
214 	 *   (Re)Begin the debouncing process, saving the new state in
215 	 *    keypad->matrix_unstable_state.
216 	 * else
217 	 *   Increase the count of number of scans with a stable state.
218 	 */
219 	if (state_changed) {
220 		memcpy(keypad->matrix_unstable_state, matrix_volatile_state,
221 			sizeof(matrix_volatile_state));
222 		keypad->stable_count = 0;
223 	} else
224 		keypad->stable_count++;
225 
226 	/*
227 	 * If the matrix is not as stable as we want reschedule scan
228 	 * in the near future.
229 	 */
230 	if (keypad->stable_count < IMX_KEYPAD_SCANS_FOR_STABILITY) {
231 		mod_timer(&keypad->check_matrix_timer,
232 			  jiffies + msecs_to_jiffies(10));
233 		return;
234 	}
235 
236 	/*
237 	 * If the matrix state is stable, fire the events and save the new
238 	 * stable state. Note, if the matrix is kept stable for longer
239 	 * (keypad->stable_count > IMX_KEYPAD_SCANS_FOR_STABILITY) all
240 	 * events have already been generated.
241 	 */
242 	if (keypad->stable_count == IMX_KEYPAD_SCANS_FOR_STABILITY) {
243 		imx_keypad_fire_events(keypad, matrix_volatile_state);
244 
245 		memcpy(keypad->matrix_stable_state, matrix_volatile_state,
246 			sizeof(matrix_volatile_state));
247 	}
248 
249 	is_zero_matrix = true;
250 	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
251 		if (matrix_volatile_state[i] != 0) {
252 			is_zero_matrix = false;
253 			break;
254 		}
255 	}
256 
257 
258 	if (is_zero_matrix) {
259 		/*
260 		 * All keys have been released. Enable only the KDI
261 		 * interrupt for future key presses (clear the KDI
262 		 * status bit and its sync chain before that).
263 		 */
264 		reg_val = readw(keypad->mmio_base + KPSR);
265 		reg_val |= KBD_STAT_KPKD | KBD_STAT_KDSC;
266 		writew(reg_val, keypad->mmio_base + KPSR);
267 
268 		reg_val = readw(keypad->mmio_base + KPSR);
269 		reg_val |= KBD_STAT_KDIE;
270 		reg_val &= ~KBD_STAT_KRIE;
271 		writew(reg_val, keypad->mmio_base + KPSR);
272 	} else {
273 		/*
274 		 * Some keys are still pressed. Schedule a rescan in
275 		 * attempt to detect multiple key presses and enable
276 		 * the KRI interrupt to react quickly to key release
277 		 * event.
278 		 */
279 		mod_timer(&keypad->check_matrix_timer,
280 			  jiffies + msecs_to_jiffies(60));
281 
282 		reg_val = readw(keypad->mmio_base + KPSR);
283 		reg_val |= KBD_STAT_KPKR | KBD_STAT_KRSS;
284 		writew(reg_val, keypad->mmio_base + KPSR);
285 
286 		reg_val = readw(keypad->mmio_base + KPSR);
287 		reg_val |= KBD_STAT_KRIE;
288 		reg_val &= ~KBD_STAT_KDIE;
289 		writew(reg_val, keypad->mmio_base + KPSR);
290 	}
291 }
292 
293 static irqreturn_t imx_keypad_irq_handler(int irq, void *dev_id)
294 {
295 	struct imx_keypad *keypad = dev_id;
296 	unsigned short reg_val;
297 
298 	reg_val = readw(keypad->mmio_base + KPSR);
299 
300 	/* Disable both interrupt types */
301 	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
302 	/* Clear interrupts status bits */
303 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
304 	writew(reg_val, keypad->mmio_base + KPSR);
305 
306 	if (keypad->enabled) {
307 		/* The matrix is supposed to be changed */
308 		keypad->stable_count = 0;
309 
310 		/* Schedule the scanning procedure near in the future */
311 		mod_timer(&keypad->check_matrix_timer,
312 			  jiffies + msecs_to_jiffies(2));
313 	}
314 
315 	return IRQ_HANDLED;
316 }
317 
318 static void imx_keypad_config(struct imx_keypad *keypad)
319 {
320 	unsigned short reg_val;
321 
322 	/*
323 	 * Include enabled rows in interrupt generation (KPCR[7:0])
324 	 * Configure keypad columns as open-drain (KPCR[15:8])
325 	 */
326 	reg_val = readw(keypad->mmio_base + KPCR);
327 	reg_val |= keypad->rows_en_mask & 0xff;		/* rows */
328 	reg_val |= (keypad->cols_en_mask & 0xff) << 8;	/* cols */
329 	writew(reg_val, keypad->mmio_base + KPCR);
330 
331 	/* Write 0's to KPDR[15:8] (Colums) */
332 	reg_val = readw(keypad->mmio_base + KPDR);
333 	reg_val &= 0x00ff;
334 	writew(reg_val, keypad->mmio_base + KPDR);
335 
336 	/* Configure columns as output, rows as input (KDDR[15:0]) */
337 	writew(0xff00, keypad->mmio_base + KDDR);
338 
339 	/*
340 	 * Clear Key Depress and Key Release status bit.
341 	 * Clear both synchronizer chain.
342 	 */
343 	reg_val = readw(keypad->mmio_base + KPSR);
344 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD |
345 		   KBD_STAT_KDSC | KBD_STAT_KRSS;
346 	writew(reg_val, keypad->mmio_base + KPSR);
347 
348 	/* Enable KDI and disable KRI (avoid false release events). */
349 	reg_val |= KBD_STAT_KDIE;
350 	reg_val &= ~KBD_STAT_KRIE;
351 	writew(reg_val, keypad->mmio_base + KPSR);
352 }
353 
354 static void imx_keypad_inhibit(struct imx_keypad *keypad)
355 {
356 	unsigned short reg_val;
357 
358 	/* Inhibit KDI and KRI interrupts. */
359 	reg_val = readw(keypad->mmio_base + KPSR);
360 	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
361 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
362 	writew(reg_val, keypad->mmio_base + KPSR);
363 
364 	/* Colums as open drain and disable all rows */
365 	reg_val = (keypad->cols_en_mask & 0xff) << 8;
366 	writew(reg_val, keypad->mmio_base + KPCR);
367 }
368 
369 static void imx_keypad_close(struct input_dev *dev)
370 {
371 	struct imx_keypad *keypad = input_get_drvdata(dev);
372 
373 	dev_dbg(&dev->dev, ">%s\n", __func__);
374 
375 	/* Mark keypad as being inactive */
376 	keypad->enabled = false;
377 	synchronize_irq(keypad->irq);
378 	del_timer_sync(&keypad->check_matrix_timer);
379 
380 	imx_keypad_inhibit(keypad);
381 
382 	/* Disable clock unit */
383 	clk_disable_unprepare(keypad->clk);
384 }
385 
386 static int imx_keypad_open(struct input_dev *dev)
387 {
388 	struct imx_keypad *keypad = input_get_drvdata(dev);
389 	int error;
390 
391 	dev_dbg(&dev->dev, ">%s\n", __func__);
392 
393 	/* Enable the kpp clock */
394 	error = clk_prepare_enable(keypad->clk);
395 	if (error)
396 		return error;
397 
398 	/* We became active from now */
399 	keypad->enabled = true;
400 
401 	imx_keypad_config(keypad);
402 
403 	/* Sanity control, not all the rows must be actived now. */
404 	if ((readw(keypad->mmio_base + KPDR) & keypad->rows_en_mask) == 0) {
405 		dev_err(&dev->dev,
406 			"too many keys pressed, control pins initialisation\n");
407 		goto open_err;
408 	}
409 
410 	return 0;
411 
412 open_err:
413 	imx_keypad_close(dev);
414 	return -EIO;
415 }
416 
417 #ifdef CONFIG_OF
418 static const struct of_device_id imx_keypad_of_match[] = {
419 	{ .compatible = "fsl,imx21-kpp", },
420 	{ /* sentinel */ }
421 };
422 MODULE_DEVICE_TABLE(of, imx_keypad_of_match);
423 #endif
424 
425 static int imx_keypad_probe(struct platform_device *pdev)
426 {
427 	const struct matrix_keymap_data *keymap_data =
428 			dev_get_platdata(&pdev->dev);
429 	struct imx_keypad *keypad;
430 	struct input_dev *input_dev;
431 	struct resource *res;
432 	int irq, error, i, row, col;
433 
434 	if (!keymap_data && !pdev->dev.of_node) {
435 		dev_err(&pdev->dev, "no keymap defined\n");
436 		return -EINVAL;
437 	}
438 
439 	irq = platform_get_irq(pdev, 0);
440 	if (irq < 0) {
441 		dev_err(&pdev->dev, "no irq defined in platform data\n");
442 		return irq;
443 	}
444 
445 	input_dev = devm_input_allocate_device(&pdev->dev);
446 	if (!input_dev) {
447 		dev_err(&pdev->dev, "failed to allocate the input device\n");
448 		return -ENOMEM;
449 	}
450 
451 	keypad = devm_kzalloc(&pdev->dev, sizeof(struct imx_keypad),
452 			      GFP_KERNEL);
453 	if (!keypad) {
454 		dev_err(&pdev->dev, "not enough memory for driver data\n");
455 		return -ENOMEM;
456 	}
457 
458 	keypad->input_dev = input_dev;
459 	keypad->irq = irq;
460 	keypad->stable_count = 0;
461 
462 	setup_timer(&keypad->check_matrix_timer,
463 		    imx_keypad_check_for_events, (unsigned long) keypad);
464 
465 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
466 	keypad->mmio_base = devm_ioremap_resource(&pdev->dev, res);
467 	if (IS_ERR(keypad->mmio_base))
468 		return PTR_ERR(keypad->mmio_base);
469 
470 	keypad->clk = devm_clk_get(&pdev->dev, NULL);
471 	if (IS_ERR(keypad->clk)) {
472 		dev_err(&pdev->dev, "failed to get keypad clock\n");
473 		return PTR_ERR(keypad->clk);
474 	}
475 
476 	/* Init the Input device */
477 	input_dev->name = pdev->name;
478 	input_dev->id.bustype = BUS_HOST;
479 	input_dev->dev.parent = &pdev->dev;
480 	input_dev->open = imx_keypad_open;
481 	input_dev->close = imx_keypad_close;
482 
483 	error = matrix_keypad_build_keymap(keymap_data, NULL,
484 					   MAX_MATRIX_KEY_ROWS,
485 					   MAX_MATRIX_KEY_COLS,
486 					   keypad->keycodes, input_dev);
487 	if (error) {
488 		dev_err(&pdev->dev, "failed to build keymap\n");
489 		return error;
490 	}
491 
492 	/* Search for rows and cols enabled */
493 	for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
494 		for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
495 			i = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
496 			if (keypad->keycodes[i] != KEY_RESERVED) {
497 				keypad->rows_en_mask |= 1 << row;
498 				keypad->cols_en_mask |= 1 << col;
499 			}
500 		}
501 	}
502 	dev_dbg(&pdev->dev, "enabled rows mask: %x\n", keypad->rows_en_mask);
503 	dev_dbg(&pdev->dev, "enabled cols mask: %x\n", keypad->cols_en_mask);
504 
505 	__set_bit(EV_REP, input_dev->evbit);
506 	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
507 	input_set_drvdata(input_dev, keypad);
508 
509 	/* Ensure that the keypad will stay dormant until opened */
510 	clk_prepare_enable(keypad->clk);
511 	imx_keypad_inhibit(keypad);
512 	clk_disable_unprepare(keypad->clk);
513 
514 	error = devm_request_irq(&pdev->dev, irq, imx_keypad_irq_handler, 0,
515 			    pdev->name, keypad);
516 	if (error) {
517 		dev_err(&pdev->dev, "failed to request IRQ\n");
518 		return error;
519 	}
520 
521 	/* Register the input device */
522 	error = input_register_device(input_dev);
523 	if (error) {
524 		dev_err(&pdev->dev, "failed to register input device\n");
525 		return error;
526 	}
527 
528 	platform_set_drvdata(pdev, keypad);
529 	device_init_wakeup(&pdev->dev, 1);
530 
531 	return 0;
532 }
533 
534 static int __maybe_unused imx_kbd_suspend(struct device *dev)
535 {
536 	struct platform_device *pdev = to_platform_device(dev);
537 	struct imx_keypad *kbd = platform_get_drvdata(pdev);
538 	struct input_dev *input_dev = kbd->input_dev;
539 
540 	/* imx kbd can wake up system even clock is disabled */
541 	mutex_lock(&input_dev->mutex);
542 
543 	if (input_dev->users)
544 		clk_disable_unprepare(kbd->clk);
545 
546 	mutex_unlock(&input_dev->mutex);
547 
548 	if (device_may_wakeup(&pdev->dev))
549 		enable_irq_wake(kbd->irq);
550 
551 	return 0;
552 }
553 
554 static int __maybe_unused imx_kbd_resume(struct device *dev)
555 {
556 	struct platform_device *pdev = to_platform_device(dev);
557 	struct imx_keypad *kbd = platform_get_drvdata(pdev);
558 	struct input_dev *input_dev = kbd->input_dev;
559 	int ret = 0;
560 
561 	if (device_may_wakeup(&pdev->dev))
562 		disable_irq_wake(kbd->irq);
563 
564 	mutex_lock(&input_dev->mutex);
565 
566 	if (input_dev->users) {
567 		ret = clk_prepare_enable(kbd->clk);
568 		if (ret)
569 			goto err_clk;
570 	}
571 
572 err_clk:
573 	mutex_unlock(&input_dev->mutex);
574 
575 	return ret;
576 }
577 
578 static SIMPLE_DEV_PM_OPS(imx_kbd_pm_ops, imx_kbd_suspend, imx_kbd_resume);
579 
580 static struct platform_driver imx_keypad_driver = {
581 	.driver		= {
582 		.name	= "imx-keypad",
583 		.owner	= THIS_MODULE,
584 		.pm	= &imx_kbd_pm_ops,
585 		.of_match_table = of_match_ptr(imx_keypad_of_match),
586 	},
587 	.probe		= imx_keypad_probe,
588 };
589 module_platform_driver(imx_keypad_driver);
590 
591 MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
592 MODULE_DESCRIPTION("IMX Keypad Port Driver");
593 MODULE_LICENSE("GPL v2");
594 MODULE_ALIAS("platform:imx-keypad");
595