drivers/input/keyboard/imx_keypad.c - kernel/msm-4.9 - Gitiles

 /*
  * Driver for the IMX keypad port.
  * Copyright (C) 2009 Alberto Panizzo <maramaopercheseimorto@gmail.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * <<Power management needs to be implemented>>.
  */

 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/input/matrix_keypad.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/timer.h>

 /*
  * Keypad Controller registers (halfword)
  */
 #define KPCR		0x00 /* Keypad Control Register */

 #define KPSR		0x02 /* Keypad Status Register */
 #define KBD_STAT_KPKD	(0x1 << 0) /* Key Press Interrupt Status bit (w1c) */
 #define KBD_STAT_KPKR	(0x1 << 1) /* Key Release Interrupt Status bit (w1c) */
 #define KBD_STAT_KDSC	(0x1 << 2) /* Key Depress Synch Chain Status bit (w1c)*/
 #define KBD_STAT_KRSS	(0x1 << 3) /* Key Release Synch Status bit (w1c)*/
 #define KBD_STAT_KDIE	(0x1 << 8) /* Key Depress Interrupt Enable Status bit */
 #define KBD_STAT_KRIE	(0x1 << 9) /* Key Release Interrupt Enable */
 #define KBD_STAT_KPPEN	(0x1 << 10) /* Keypad Clock Enable */

 #define KDDR		0x04 /* Keypad Data Direction Register */
 #define KPDR		0x06 /* Keypad Data Register */

 #define MAX_MATRIX_KEY_ROWS	8
 #define MAX_MATRIX_KEY_COLS	8
 #define MATRIX_ROW_SHIFT	3

 #define MAX_MATRIX_KEY_NUM	(MAX_MATRIX_KEY_ROWS * MAX_MATRIX_KEY_COLS)

 struct imx_keypad {

 	struct clk *clk;
 	struct input_dev *input_dev;
 	void __iomem *mmio_base;

 	int			irq;
 	struct timer_list	check_matrix_timer;

 	/*
 	 * The matrix is stable only if no changes are detected after
 	 * IMX_KEYPAD_SCANS_FOR_STABILITY scans
 	 */
 #define IMX_KEYPAD_SCANS_FOR_STABILITY 3
 	int			stable_count;

 	bool			enabled;

 	/* Masks for enabled rows/cols */
 	unsigned short		rows_en_mask;
 	unsigned short		cols_en_mask;

 	unsigned short		keycodes[MAX_MATRIX_KEY_NUM];

 	/*
 	 * Matrix states:
 	 * -stable: achieved after a complete debounce process.
 	 * -unstable: used in the debouncing process.
 	 */
 	unsigned short		matrix_stable_state[MAX_MATRIX_KEY_COLS];
 	unsigned short		matrix_unstable_state[MAX_MATRIX_KEY_COLS];
 };

 /* Scan the matrix and return the new state in *matrix_volatile_state. */
 static void imx_keypad_scan_matrix(struct imx_keypad *keypad,
 				  unsigned short *matrix_volatile_state)
 {
 	int col;
 	unsigned short reg_val;

 	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
 		if ((keypad->cols_en_mask & (1 << col)) == 0)
 			continue;
 		/*
 		 * Discharge keypad capacitance:
 		 * 2. write 1s on column data.
 		 * 3. configure columns as totem-pole to discharge capacitance.
 		 * 4. configure columns as open-drain.
 		 */
 		reg_val = readw(keypad->mmio_base + KPDR);
 		reg_val |= 0xff00;
 		writew(reg_val, keypad->mmio_base + KPDR);

 		reg_val = readw(keypad->mmio_base + KPCR);
 		reg_val &= ~((keypad->cols_en_mask & 0xff) << 8);
 		writew(reg_val, keypad->mmio_base + KPCR);

 		udelay(2);

 		reg_val = readw(keypad->mmio_base + KPCR);
 		reg_val |= (keypad->cols_en_mask & 0xff) << 8;
 		writew(reg_val, keypad->mmio_base + KPCR);

 		/*
 		 * 5. Write a single column to 0, others to 1.
 		 * 6. Sample row inputs and save data.
 		 * 7. Repeat steps 2 - 6 for remaining columns.
 		 */
 		reg_val = readw(keypad->mmio_base + KPDR);
 		reg_val &= ~(1 << (8 + col));
 		writew(reg_val, keypad->mmio_base + KPDR);

 		/*
 		 * Delay added to avoid propagating the 0 from column to row
 		 * when scanning.
 		 */
 		udelay(5);

 		/*
 		 * 1s in matrix_volatile_state[col] means key pressures
 		 * throw data from non enabled rows.
 		 */
 		reg_val = readw(keypad->mmio_base + KPDR);
 		matrix_volatile_state[col] = (~reg_val) & keypad->rows_en_mask;
 	}

 	/*
 	 * Return in standby mode:
 	 * 9. write 0s to columns
 	 */
 	reg_val = readw(keypad->mmio_base + KPDR);
 	reg_val &= 0x00ff;
 	writew(reg_val, keypad->mmio_base + KPDR);
 }

 /*
  * Compare the new matrix state (volatile) with the stable one stored in
  * keypad->matrix_stable_state and fire events if changes are detected.
  */
 static void imx_keypad_fire_events(struct imx_keypad *keypad,
 				   unsigned short *matrix_volatile_state)
 {
 	struct input_dev *input_dev = keypad->input_dev;
 	int row, col;

 	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
 		unsigned short bits_changed;
 		int code;

 		if ((keypad->cols_en_mask & (1 << col)) == 0)
 			continue; /* Column is not enabled */

 		bits_changed = keypad->matrix_stable_state[col] ^
 						matrix_volatile_state[col];

 		if (bits_changed == 0)
 			continue; /* Column does not contain changes */

 		for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
 			if ((keypad->rows_en_mask & (1 << row)) == 0)
 				continue; /* Row is not enabled */
 			if ((bits_changed & (1 << row)) == 0)
 				continue; /* Row does not contain changes */

 			code = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
 			input_event(input_dev, EV_MSC, MSC_SCAN, code);
 			input_report_key(input_dev, keypad->keycodes[code],
 				matrix_volatile_state[col] & (1 << row));
 			dev_dbg(&input_dev->dev, "Event code: %d, val: %d",
 				keypad->keycodes[code],
 				matrix_volatile_state[col] & (1 << row));
 		}
 	}
 	input_sync(input_dev);
 }

 /*
  * imx_keypad_check_for_events is the timer handler.
  */
 static void imx_keypad_check_for_events(unsigned long data)
 {
 	struct imx_keypad *keypad = (struct imx_keypad *) data;
 	unsigned short matrix_volatile_state[MAX_MATRIX_KEY_COLS];
 	unsigned short reg_val;
 	bool state_changed, is_zero_matrix;
 	int i;

 	memset(matrix_volatile_state, 0, sizeof(matrix_volatile_state));

 	imx_keypad_scan_matrix(keypad, matrix_volatile_state);

 	state_changed = false;
 	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
 		if ((keypad->cols_en_mask & (1 << i)) == 0)
 			continue;

 		if (keypad->matrix_unstable_state[i] ^ matrix_volatile_state[i]) {
 			state_changed = true;
 			break;
 		}
 	}

 	/*
 	 * If the matrix state is changed from the previous scan
 	 *   (Re)Begin the debouncing process, saving the new state in
 	 *    keypad->matrix_unstable_state.
 	 * else
 	 *   Increase the count of number of scans with a stable state.
 	 */
 	if (state_changed) {
 		memcpy(keypad->matrix_unstable_state, matrix_volatile_state,
 			sizeof(matrix_volatile_state));
 		keypad->stable_count = 0;
 	} else
 		keypad->stable_count++;

 	/*
 	 * If the matrix is not as stable as we want reschedule scan
 	 * in the near future.
 	 */
 	if (keypad->stable_count < IMX_KEYPAD_SCANS_FOR_STABILITY) {
 		mod_timer(&keypad->check_matrix_timer,
 			  jiffies + msecs_to_jiffies(10));
 		return;
 	}

 	/*
 	 * If the matrix state is stable, fire the events and save the new
 	 * stable state. Note, if the matrix is kept stable for longer
 	 * (keypad->stable_count > IMX_KEYPAD_SCANS_FOR_STABILITY) all
 	 * events have already been generated.
 	 */
 	if (keypad->stable_count == IMX_KEYPAD_SCANS_FOR_STABILITY) {
 		imx_keypad_fire_events(keypad, matrix_volatile_state);

 		memcpy(keypad->matrix_stable_state, matrix_volatile_state,
 			sizeof(matrix_volatile_state));
 	}

 	is_zero_matrix = true;
 	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
 		if (matrix_volatile_state[i] != 0) {
 			is_zero_matrix = false;
 			break;
 		}
 	}


 	if (is_zero_matrix) {
 		/*
 		 * All keys have been released. Enable only the KDI
 		 * interrupt for future key presses (clear the KDI
 		 * status bit and its sync chain before that).
 		 */
 		reg_val = readw(keypad->mmio_base + KPSR);
 		reg_val |= KBD_STAT_KPKD | KBD_STAT_KDSC;
 		writew(reg_val, keypad->mmio_base + KPSR);

 		reg_val = readw(keypad->mmio_base + KPSR);
 		reg_val |= KBD_STAT_KDIE;
 		reg_val &= ~KBD_STAT_KRIE;
 		writew(reg_val, keypad->mmio_base + KPSR);
 	} else {
 		/*
 		 * Some keys are still pressed. Schedule a rescan in
 		 * attempt to detect multiple key presses and enable
 		 * the KRI interrupt to react quickly to key release
 		 * event.
 		 */
 		mod_timer(&keypad->check_matrix_timer,
 			  jiffies + msecs_to_jiffies(60));

 		reg_val = readw(keypad->mmio_base + KPSR);
 		reg_val |= KBD_STAT_KPKR | KBD_STAT_KRSS;
 		writew(reg_val, keypad->mmio_base + KPSR);

 		reg_val = readw(keypad->mmio_base + KPSR);
 		reg_val |= KBD_STAT_KRIE;
 		reg_val &= ~KBD_STAT_KDIE;
 		writew(reg_val, keypad->mmio_base + KPSR);
 	}
 }

 static irqreturn_t imx_keypad_irq_handler(int irq, void *dev_id)
 {
 	struct imx_keypad *keypad = dev_id;
 	unsigned short reg_val;

 	reg_val = readw(keypad->mmio_base + KPSR);

 	/* Disable both interrupt types */
 	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
 	/* Clear interrupts status bits */
 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
 	writew(reg_val, keypad->mmio_base + KPSR);

 	if (keypad->enabled) {
 		/* The matrix is supposed to be changed */
 		keypad->stable_count = 0;

 		/* Schedule the scanning procedure near in the future */
 		mod_timer(&keypad->check_matrix_timer,
 			  jiffies + msecs_to_jiffies(2));
 	}

 	return IRQ_HANDLED;
 }

 static void imx_keypad_config(struct imx_keypad *keypad)
 {
 	unsigned short reg_val;

 	/*
 	 * Include enabled rows in interrupt generation (KPCR[7:0])
 	 * Configure keypad columns as open-drain (KPCR[15:8])
 	 */
 	reg_val = readw(keypad->mmio_base + KPCR);
 	reg_val |= keypad->rows_en_mask & 0xff;		/* rows */
 	reg_val |= (keypad->cols_en_mask & 0xff) << 8;	/* cols */
 	writew(reg_val, keypad->mmio_base + KPCR);

 	/* Write 0's to KPDR[15:8] (Colums) */
 	reg_val = readw(keypad->mmio_base + KPDR);
 	reg_val &= 0x00ff;
 	writew(reg_val, keypad->mmio_base + KPDR);

 	/* Configure columns as output, rows as input (KDDR[15:0]) */
 	writew(0xff00, keypad->mmio_base + KDDR);

 	/*
 	 * Clear Key Depress and Key Release status bit.
 	 * Clear both synchronizer chain.
 	 */
 	reg_val = readw(keypad->mmio_base + KPSR);
 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD |
 		   KBD_STAT_KDSC | KBD_STAT_KRSS;
 	writew(reg_val, keypad->mmio_base + KPSR);

 	/* Enable KDI and disable KRI (avoid false release events). */
 	reg_val |= KBD_STAT_KDIE;
 	reg_val &= ~KBD_STAT_KRIE;
 	writew(reg_val, keypad->mmio_base + KPSR);
 }

 static void imx_keypad_inhibit(struct imx_keypad *keypad)
 {
 	unsigned short reg_val;

 	/* Inhibit KDI and KRI interrupts. */
 	reg_val = readw(keypad->mmio_base + KPSR);
 	reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
 	reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
 	writew(reg_val, keypad->mmio_base + KPSR);

 	/* Colums as open drain and disable all rows */
 	reg_val = (keypad->cols_en_mask & 0xff) << 8;
 	writew(reg_val, keypad->mmio_base + KPCR);
 }

 static void imx_keypad_close(struct input_dev *dev)
 {
 	struct imx_keypad *keypad = input_get_drvdata(dev);

 	dev_dbg(&dev->dev, ">%s\n", __func__);

 	/* Mark keypad as being inactive */
 	keypad->enabled = false;
 	synchronize_irq(keypad->irq);
 	del_timer_sync(&keypad->check_matrix_timer);

 	imx_keypad_inhibit(keypad);

 	/* Disable clock unit */
 	clk_disable_unprepare(keypad->clk);
 }

 static int imx_keypad_open(struct input_dev *dev)
 {
 	struct imx_keypad *keypad = input_get_drvdata(dev);
 	int error;

 	dev_dbg(&dev->dev, ">%s\n", __func__);

 	/* Enable the kpp clock */
 	error = clk_prepare_enable(keypad->clk);
 	if (error)
 		return error;

 	/* We became active from now */
 	keypad->enabled = true;

 	imx_keypad_config(keypad);

 	/* Sanity control, not all the rows must be actived now. */
 	if ((readw(keypad->mmio_base + KPDR) & keypad->rows_en_mask) == 0) {
 		dev_err(&dev->dev,
 			"too many keys pressed, control pins initialisation\n");
 		goto open_err;
 	}

 	return 0;

 open_err:
 	imx_keypad_close(dev);
 	return -EIO;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id imx_keypad_of_match[] = {
 	{ .compatible = "fsl,imx21-kpp", },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, imx_keypad_of_match);
 #endif

 static int imx_keypad_probe(struct platform_device *pdev)
 {
 	const struct matrix_keymap_data *keymap_data =
 			dev_get_platdata(&pdev->dev);
 	struct imx_keypad *keypad;
 	struct input_dev *input_dev;
 	struct resource *res;
 	int irq, error, i, row, col;

 	if (!keymap_data && !pdev->dev.of_node) {
 		dev_err(&pdev->dev, "no keymap defined\n");
 		return -EINVAL;
 	}

 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0) {
 		dev_err(&pdev->dev, "no irq defined in platform data\n");
 		return irq;
 	}

 	input_dev = devm_input_allocate_device(&pdev->dev);
 	if (!input_dev) {
 		dev_err(&pdev->dev, "failed to allocate the input device\n");
 		return -ENOMEM;
 	}

 	keypad = devm_kzalloc(&pdev->dev, sizeof(struct imx_keypad),
 			      GFP_KERNEL);
 	if (!keypad) {
 		dev_err(&pdev->dev, "not enough memory for driver data\n");
 		return -ENOMEM;
 	}

 	keypad->input_dev = input_dev;
 	keypad->irq = irq;
 	keypad->stable_count = 0;

 	setup_timer(&keypad->check_matrix_timer,
 		    imx_keypad_check_for_events, (unsigned long) keypad);

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	keypad->mmio_base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(keypad->mmio_base))
 		return PTR_ERR(keypad->mmio_base);

 	keypad->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(keypad->clk)) {
 		dev_err(&pdev->dev, "failed to get keypad clock\n");
 		return PTR_ERR(keypad->clk);
 	}

 	/* Init the Input device */
 	input_dev->name = pdev->name;
 	input_dev->id.bustype = BUS_HOST;
 	input_dev->dev.parent = &pdev->dev;
 	input_dev->open = imx_keypad_open;
 	input_dev->close = imx_keypad_close;

 	error = matrix_keypad_build_keymap(keymap_data, NULL,
 					   MAX_MATRIX_KEY_ROWS,
 					   MAX_MATRIX_KEY_COLS,
 					   keypad->keycodes, input_dev);
 	if (error) {
 		dev_err(&pdev->dev, "failed to build keymap\n");
 		return error;
 	}

 	/* Search for rows and cols enabled */
 	for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
 		for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
 			i = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
 			if (keypad->keycodes[i] != KEY_RESERVED) {
 				keypad->rows_en_mask |= 1 << row;
 				keypad->cols_en_mask |= 1 << col;
 			}
 		}
 	}
 	dev_dbg(&pdev->dev, "enabled rows mask: %x\n", keypad->rows_en_mask);
 	dev_dbg(&pdev->dev, "enabled cols mask: %x\n", keypad->cols_en_mask);

 	__set_bit(EV_REP, input_dev->evbit);
 	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
 	input_set_drvdata(input_dev, keypad);

 	/* Ensure that the keypad will stay dormant until opened */
 	clk_prepare_enable(keypad->clk);
 	imx_keypad_inhibit(keypad);
 	clk_disable_unprepare(keypad->clk);

 	error = devm_request_irq(&pdev->dev, irq, imx_keypad_irq_handler, 0,
 			    pdev->name, keypad);
 	if (error) {
 		dev_err(&pdev->dev, "failed to request IRQ\n");
 		return error;
 	}

 	/* Register the input device */
 	error = input_register_device(input_dev);
 	if (error) {
 		dev_err(&pdev->dev, "failed to register input device\n");
 		return error;
 	}

 	platform_set_drvdata(pdev, keypad);
 	device_init_wakeup(&pdev->dev, 1);

 	return 0;
 }

 #ifdef CONFIG_PM_SLEEP
 static int imx_kbd_suspend(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct imx_keypad *kbd = platform_get_drvdata(pdev);
 	struct input_dev *input_dev = kbd->input_dev;

 	/* imx kbd can wake up system even clock is disabled */
 	mutex_lock(&input_dev->mutex);

 	if (input_dev->users)
 		clk_disable_unprepare(kbd->clk);

 	mutex_unlock(&input_dev->mutex);

 	if (device_may_wakeup(&pdev->dev))
 		enable_irq_wake(kbd->irq);

 	return 0;
 }

 static int imx_kbd_resume(struct device *dev)
 {
 	struct platform_device *pdev = to_platform_device(dev);
 	struct imx_keypad *kbd = platform_get_drvdata(pdev);
 	struct input_dev *input_dev = kbd->input_dev;
 	int ret = 0;

 	if (device_may_wakeup(&pdev->dev))
 		disable_irq_wake(kbd->irq);

 	mutex_lock(&input_dev->mutex);

 	if (input_dev->users) {
 		ret = clk_prepare_enable(kbd->clk);
 		if (ret)
 			goto err_clk;
 	}

 err_clk:
 	mutex_unlock(&input_dev->mutex);

 	return ret;
 }
 #endif

 static SIMPLE_DEV_PM_OPS(imx_kbd_pm_ops, imx_kbd_suspend, imx_kbd_resume);

 static struct platform_driver imx_keypad_driver = {
 	.driver		= {
 		.name	= "imx-keypad",
 		.owner	= THIS_MODULE,
 		.pm	= &imx_kbd_pm_ops,
 		.of_match_table = of_match_ptr(imx_keypad_of_match),
 	},
 	.probe		= imx_keypad_probe,
 };
 module_platform_driver(imx_keypad_driver);

 MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
 MODULE_DESCRIPTION("IMX Keypad Port Driver");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:imx-keypad");
	/*
	* Driver for the IMX keypad port.
	* Copyright (C) 2009 Alberto Panizzo <maramaopercheseimorto@gmail.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* <<Power management needs to be implemented>>.
	*/

	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/device.h>
	#include <linux/err.h>
	#include <linux/input/matrix_keypad.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/jiffies.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>
	#include <linux/timer.h>

	/*
	* Keypad Controller registers (halfword)
	*/
	#define KPCR 0x00 /* Keypad Control Register */

	#define KPSR 0x02 /* Keypad Status Register */
	#define KBD_STAT_KPKD (0x1 << 0) /* Key Press Interrupt Status bit (w1c) */
	#define KBD_STAT_KPKR (0x1 << 1) /* Key Release Interrupt Status bit (w1c) */
	#define KBD_STAT_KDSC (0x1 << 2) /* Key Depress Synch Chain Status bit (w1c)*/
	#define KBD_STAT_KRSS (0x1 << 3) /* Key Release Synch Status bit (w1c)*/
	#define KBD_STAT_KDIE (0x1 << 8) /* Key Depress Interrupt Enable Status bit */
	#define KBD_STAT_KRIE (0x1 << 9) /* Key Release Interrupt Enable */
	#define KBD_STAT_KPPEN (0x1 << 10) /* Keypad Clock Enable */

	#define KDDR 0x04 /* Keypad Data Direction Register */
	#define KPDR 0x06 /* Keypad Data Register */

	#define MAX_MATRIX_KEY_ROWS 8
	#define MAX_MATRIX_KEY_COLS 8
	#define MATRIX_ROW_SHIFT 3

	#define MAX_MATRIX_KEY_NUM (MAX_MATRIX_KEY_ROWS * MAX_MATRIX_KEY_COLS)

	struct imx_keypad {

	struct clk *clk;
	struct input_dev *input_dev;
	void __iomem *mmio_base;

	int irq;
	struct timer_list check_matrix_timer;

	/*
	* The matrix is stable only if no changes are detected after
	* IMX_KEYPAD_SCANS_FOR_STABILITY scans
	*/
	#define IMX_KEYPAD_SCANS_FOR_STABILITY 3
	int stable_count;

	bool enabled;

	/* Masks for enabled rows/cols */
	unsigned short rows_en_mask;
	unsigned short cols_en_mask;

	unsigned short keycodes[MAX_MATRIX_KEY_NUM];

	/*
	* Matrix states:
	* -stable: achieved after a complete debounce process.
	* -unstable: used in the debouncing process.
	*/
	unsigned short matrix_stable_state[MAX_MATRIX_KEY_COLS];
	unsigned short matrix_unstable_state[MAX_MATRIX_KEY_COLS];
	};

	/* Scan the matrix and return the new state in matrix_volatile_state. /
	static void imx_keypad_scan_matrix(struct imx_keypad *keypad,
	unsigned short *matrix_volatile_state)
	{
	int col;
	unsigned short reg_val;

	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
	if ((keypad->cols_en_mask & (1 << col)) == 0)
	continue;
	/*
	* Discharge keypad capacitance:
	* 2. write 1s on column data.
	* 3. configure columns as totem-pole to discharge capacitance.
	* 4. configure columns as open-drain.
	*/
	reg_val = readw(keypad->mmio_base + KPDR);
	reg_val \|= 0xff00;
	writew(reg_val, keypad->mmio_base + KPDR);

	reg_val = readw(keypad->mmio_base + KPCR);
	reg_val &= ~((keypad->cols_en_mask & 0xff) << 8);
	writew(reg_val, keypad->mmio_base + KPCR);

	udelay(2);

	reg_val = readw(keypad->mmio_base + KPCR);
	reg_val \|= (keypad->cols_en_mask & 0xff) << 8;
	writew(reg_val, keypad->mmio_base + KPCR);

	/*
	* 5. Write a single column to 0, others to 1.
	* 6. Sample row inputs and save data.
	* 7. Repeat steps 2 - 6 for remaining columns.
	*/
	reg_val = readw(keypad->mmio_base + KPDR);
	reg_val &= ~(1 << (8 + col));
	writew(reg_val, keypad->mmio_base + KPDR);

	/*
	* Delay added to avoid propagating the 0 from column to row
	* when scanning.
	*/
	udelay(5);

	/*
	* 1s in matrix_volatile_state[col] means key pressures
	* throw data from non enabled rows.
	*/
	reg_val = readw(keypad->mmio_base + KPDR);
	matrix_volatile_state[col] = (~reg_val) & keypad->rows_en_mask;
	}

	/*
	* Return in standby mode:
	* 9. write 0s to columns
	*/
	reg_val = readw(keypad->mmio_base + KPDR);
	reg_val &= 0x00ff;
	writew(reg_val, keypad->mmio_base + KPDR);
	}

	/*
	* Compare the new matrix state (volatile) with the stable one stored in
	* keypad->matrix_stable_state and fire events if changes are detected.
	*/
	static void imx_keypad_fire_events(struct imx_keypad *keypad,
	unsigned short *matrix_volatile_state)
	{
	struct input_dev *input_dev = keypad->input_dev;
	int row, col;

	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
	unsigned short bits_changed;
	int code;

	if ((keypad->cols_en_mask & (1 << col)) == 0)
	continue; /* Column is not enabled */

	bits_changed = keypad->matrix_stable_state[col] ^
	matrix_volatile_state[col];

	if (bits_changed == 0)
	continue; /* Column does not contain changes */

	for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
	if ((keypad->rows_en_mask & (1 << row)) == 0)
	continue; /* Row is not enabled */
	if ((bits_changed & (1 << row)) == 0)
	continue; /* Row does not contain changes */

	code = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
	input_event(input_dev, EV_MSC, MSC_SCAN, code);
	input_report_key(input_dev, keypad->keycodes[code],
	matrix_volatile_state[col] & (1 << row));
	dev_dbg(&input_dev->dev, "Event code: %d, val: %d",
	keypad->keycodes[code],
	matrix_volatile_state[col] & (1 << row));
	}
	}
	input_sync(input_dev);
	}

	/*
	* imx_keypad_check_for_events is the timer handler.
	*/
	static void imx_keypad_check_for_events(unsigned long data)
	{
	struct imx_keypad keypad = (struct imx_keypad ) data;
	unsigned short matrix_volatile_state[MAX_MATRIX_KEY_COLS];
	unsigned short reg_val;
	bool state_changed, is_zero_matrix;
	int i;

	memset(matrix_volatile_state, 0, sizeof(matrix_volatile_state));

	imx_keypad_scan_matrix(keypad, matrix_volatile_state);

	state_changed = false;
	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
	if ((keypad->cols_en_mask & (1 << i)) == 0)
	continue;

	if (keypad->matrix_unstable_state[i] ^ matrix_volatile_state[i]) {
	state_changed = true;
	break;
	}
	}

	/*
	* If the matrix state is changed from the previous scan
	* (Re)Begin the debouncing process, saving the new state in
	* keypad->matrix_unstable_state.
	* else
	* Increase the count of number of scans with a stable state.
	*/
	if (state_changed) {
	memcpy(keypad->matrix_unstable_state, matrix_volatile_state,
	sizeof(matrix_volatile_state));
	keypad->stable_count = 0;
	} else
	keypad->stable_count++;

	/*
	* If the matrix is not as stable as we want reschedule scan
	* in the near future.
	*/
	if (keypad->stable_count < IMX_KEYPAD_SCANS_FOR_STABILITY) {
	mod_timer(&keypad->check_matrix_timer,
	jiffies + msecs_to_jiffies(10));
	return;
	}

	/*
	* If the matrix state is stable, fire the events and save the new
	* stable state. Note, if the matrix is kept stable for longer
	* (keypad->stable_count > IMX_KEYPAD_SCANS_FOR_STABILITY) all
	* events have already been generated.
	*/
	if (keypad->stable_count == IMX_KEYPAD_SCANS_FOR_STABILITY) {
	imx_keypad_fire_events(keypad, matrix_volatile_state);

	memcpy(keypad->matrix_stable_state, matrix_volatile_state,
	sizeof(matrix_volatile_state));
	}

	is_zero_matrix = true;
	for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
	if (matrix_volatile_state[i] != 0) {
	is_zero_matrix = false;
	break;
	}
	}


	if (is_zero_matrix) {
	/*
	* All keys have been released. Enable only the KDI
	* interrupt for future key presses (clear the KDI
	* status bit and its sync chain before that).
	*/
	reg_val = readw(keypad->mmio_base + KPSR);
	reg_val \|= KBD_STAT_KPKD \| KBD_STAT_KDSC;
	writew(reg_val, keypad->mmio_base + KPSR);

	reg_val = readw(keypad->mmio_base + KPSR);
	reg_val \|= KBD_STAT_KDIE;
	reg_val &= ~KBD_STAT_KRIE;
	writew(reg_val, keypad->mmio_base + KPSR);
	} else {
	/*
	* Some keys are still pressed. Schedule a rescan in
	* attempt to detect multiple key presses and enable
	* the KRI interrupt to react quickly to key release
	* event.
	*/
	mod_timer(&keypad->check_matrix_timer,
	jiffies + msecs_to_jiffies(60));

	reg_val = readw(keypad->mmio_base + KPSR);
	reg_val \|= KBD_STAT_KPKR \| KBD_STAT_KRSS;
	writew(reg_val, keypad->mmio_base + KPSR);

	reg_val = readw(keypad->mmio_base + KPSR);
	reg_val \|= KBD_STAT_KRIE;
	reg_val &= ~KBD_STAT_KDIE;
	writew(reg_val, keypad->mmio_base + KPSR);
	}
	}

	static irqreturn_t imx_keypad_irq_handler(int irq, void *dev_id)
	{
	struct imx_keypad *keypad = dev_id;
	unsigned short reg_val;

	reg_val = readw(keypad->mmio_base + KPSR);

	/* Disable both interrupt types */
	reg_val &= ~(KBD_STAT_KRIE \| KBD_STAT_KDIE);
	/* Clear interrupts status bits */
	reg_val \|= KBD_STAT_KPKR \| KBD_STAT_KPKD;
	writew(reg_val, keypad->mmio_base + KPSR);

	if (keypad->enabled) {
	/* The matrix is supposed to be changed */
	keypad->stable_count = 0;

	/* Schedule the scanning procedure near in the future */
	mod_timer(&keypad->check_matrix_timer,
	jiffies + msecs_to_jiffies(2));
	}

	return IRQ_HANDLED;
	}

	static void imx_keypad_config(struct imx_keypad *keypad)
	{
	unsigned short reg_val;

	/*
	* Include enabled rows in interrupt generation (KPCR[7:0])
	* Configure keypad columns as open-drain (KPCR[15:8])
	*/
	reg_val = readw(keypad->mmio_base + KPCR);
	reg_val \|= keypad->rows_en_mask & 0xff; /* rows */
	reg_val \|= (keypad->cols_en_mask & 0xff) << 8; /* cols */
	writew(reg_val, keypad->mmio_base + KPCR);

	/* Write 0's to KPDR[15:8] (Colums) */
	reg_val = readw(keypad->mmio_base + KPDR);
	reg_val &= 0x00ff;
	writew(reg_val, keypad->mmio_base + KPDR);

	/* Configure columns as output, rows as input (KDDR[15:0]) */
	writew(0xff00, keypad->mmio_base + KDDR);

	/*
	* Clear Key Depress and Key Release status bit.
	* Clear both synchronizer chain.
	*/
	reg_val = readw(keypad->mmio_base + KPSR);
	reg_val \|= KBD_STAT_KPKR \| KBD_STAT_KPKD \|
	KBD_STAT_KDSC \| KBD_STAT_KRSS;
	writew(reg_val, keypad->mmio_base + KPSR);

	/* Enable KDI and disable KRI (avoid false release events). */
	reg_val \|= KBD_STAT_KDIE;
	reg_val &= ~KBD_STAT_KRIE;
	writew(reg_val, keypad->mmio_base + KPSR);
	}

	static void imx_keypad_inhibit(struct imx_keypad *keypad)
	{
	unsigned short reg_val;

	/* Inhibit KDI and KRI interrupts. */
	reg_val = readw(keypad->mmio_base + KPSR);
	reg_val &= ~(KBD_STAT_KRIE \| KBD_STAT_KDIE);
	reg_val \|= KBD_STAT_KPKR \| KBD_STAT_KPKD;
	writew(reg_val, keypad->mmio_base + KPSR);

	/* Colums as open drain and disable all rows */
	reg_val = (keypad->cols_en_mask & 0xff) << 8;
	writew(reg_val, keypad->mmio_base + KPCR);
	}

	static void imx_keypad_close(struct input_dev *dev)
	{
	struct imx_keypad *keypad = input_get_drvdata(dev);

	dev_dbg(&dev->dev, ">%s\n", __func__);

	/* Mark keypad as being inactive */
	keypad->enabled = false;
	synchronize_irq(keypad->irq);
	del_timer_sync(&keypad->check_matrix_timer);

	imx_keypad_inhibit(keypad);

	/* Disable clock unit */
	clk_disable_unprepare(keypad->clk);
	}

	static int imx_keypad_open(struct input_dev *dev)
	{
	struct imx_keypad *keypad = input_get_drvdata(dev);
	int error;

	dev_dbg(&dev->dev, ">%s\n", __func__);

	/* Enable the kpp clock */
	error = clk_prepare_enable(keypad->clk);
	if (error)
	return error;

	/* We became active from now */
	keypad->enabled = true;

	imx_keypad_config(keypad);

	/* Sanity control, not all the rows must be actived now. */
	if ((readw(keypad->mmio_base + KPDR) & keypad->rows_en_mask) == 0) {
	dev_err(&dev->dev,
	"too many keys pressed, control pins initialisation\n");
	goto open_err;
	}

	return 0;

	open_err:
	imx_keypad_close(dev);
	return -EIO;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id imx_keypad_of_match[] = {
	{ .compatible = "fsl,imx21-kpp", },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, imx_keypad_of_match);
	#endif

	static int imx_keypad_probe(struct platform_device *pdev)
	{
	const struct matrix_keymap_data *keymap_data =
	dev_get_platdata(&pdev->dev);
	struct imx_keypad *keypad;
	struct input_dev *input_dev;
	struct resource *res;
	int irq, error, i, row, col;

	if (!keymap_data && !pdev->dev.of_node) {
	dev_err(&pdev->dev, "no keymap defined\n");
	return -EINVAL;
	}

	irq = platform_get_irq(pdev, 0);
	if (irq < 0) {
	dev_err(&pdev->dev, "no irq defined in platform data\n");
	return irq;
	}

	input_dev = devm_input_allocate_device(&pdev->dev);
	if (!input_dev) {
	dev_err(&pdev->dev, "failed to allocate the input device\n");
	return -ENOMEM;
	}

	keypad = devm_kzalloc(&pdev->dev, sizeof(struct imx_keypad),
	GFP_KERNEL);
	if (!keypad) {
	dev_err(&pdev->dev, "not enough memory for driver data\n");
	return -ENOMEM;
	}

	keypad->input_dev = input_dev;
	keypad->irq = irq;
	keypad->stable_count = 0;

	setup_timer(&keypad->check_matrix_timer,
	imx_keypad_check_for_events, (unsigned long) keypad);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	keypad->mmio_base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(keypad->mmio_base))
	return PTR_ERR(keypad->mmio_base);

	keypad->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(keypad->clk)) {
	dev_err(&pdev->dev, "failed to get keypad clock\n");
	return PTR_ERR(keypad->clk);
	}

	/* Init the Input device */
	input_dev->name = pdev->name;
	input_dev->id.bustype = BUS_HOST;
	input_dev->dev.parent = &pdev->dev;
	input_dev->open = imx_keypad_open;
	input_dev->close = imx_keypad_close;

	error = matrix_keypad_build_keymap(keymap_data, NULL,
	MAX_MATRIX_KEY_ROWS,
	MAX_MATRIX_KEY_COLS,
	keypad->keycodes, input_dev);
	if (error) {
	dev_err(&pdev->dev, "failed to build keymap\n");
	return error;
	}

	/* Search for rows and cols enabled */
	for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
	for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
	i = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
	if (keypad->keycodes[i] != KEY_RESERVED) {
	keypad->rows_en_mask \|= 1 << row;
	keypad->cols_en_mask \|= 1 << col;
	}
	}
	}
	dev_dbg(&pdev->dev, "enabled rows mask: %x\n", keypad->rows_en_mask);
	dev_dbg(&pdev->dev, "enabled cols mask: %x\n", keypad->cols_en_mask);

	__set_bit(EV_REP, input_dev->evbit);
	input_set_capability(input_dev, EV_MSC, MSC_SCAN);
	input_set_drvdata(input_dev, keypad);

	/* Ensure that the keypad will stay dormant until opened */
	clk_prepare_enable(keypad->clk);
	imx_keypad_inhibit(keypad);
	clk_disable_unprepare(keypad->clk);

	error = devm_request_irq(&pdev->dev, irq, imx_keypad_irq_handler, 0,
	pdev->name, keypad);
	if (error) {
	dev_err(&pdev->dev, "failed to request IRQ\n");
	return error;
	}

	/* Register the input device */
	error = input_register_device(input_dev);
	if (error) {
	dev_err(&pdev->dev, "failed to register input device\n");
	return error;
	}

	platform_set_drvdata(pdev, keypad);
	device_init_wakeup(&pdev->dev, 1);

	return 0;
	}

	#ifdef CONFIG_PM_SLEEP
	static int imx_kbd_suspend(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct imx_keypad *kbd = platform_get_drvdata(pdev);
	struct input_dev *input_dev = kbd->input_dev;

	/* imx kbd can wake up system even clock is disabled */
	mutex_lock(&input_dev->mutex);

	if (input_dev->users)
	clk_disable_unprepare(kbd->clk);

	mutex_unlock(&input_dev->mutex);

	if (device_may_wakeup(&pdev->dev))
	enable_irq_wake(kbd->irq);

	return 0;
	}

	static int imx_kbd_resume(struct device *dev)
	{
	struct platform_device *pdev = to_platform_device(dev);
	struct imx_keypad *kbd = platform_get_drvdata(pdev);
	struct input_dev *input_dev = kbd->input_dev;
	int ret = 0;

	if (device_may_wakeup(&pdev->dev))
	disable_irq_wake(kbd->irq);

	mutex_lock(&input_dev->mutex);

	if (input_dev->users) {
	ret = clk_prepare_enable(kbd->clk);
	if (ret)
	goto err_clk;
	}

	err_clk:
	mutex_unlock(&input_dev->mutex);

	return ret;
	}
	#endif

	static SIMPLE_DEV_PM_OPS(imx_kbd_pm_ops, imx_kbd_suspend, imx_kbd_resume);

	static struct platform_driver imx_keypad_driver = {
	.driver = {
	.name = "imx-keypad",
	.owner = THIS_MODULE,
	.pm = &imx_kbd_pm_ops,
	.of_match_table = of_match_ptr(imx_keypad_of_match),
	},
	.probe = imx_keypad_probe,
	};
	module_platform_driver(imx_keypad_driver);

	MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
	MODULE_DESCRIPTION("IMX Keypad Port Driver");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:imx-keypad");