text: /*
   * 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/init.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/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 */
  	writew(0xff00, 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;
  }
  
  static int __devinit imx_keypad_probe(struct platform_device *pdev)
  {
  	const struct matrix_keymap_data *keymap_data = pdev->dev.platform_data;
  	struct imx_keypad *keypad;
  	struct input_dev *input_dev;
  	struct resource *res;
  	int irq, error, i;
  
  	if (keymap_data == NULL) {
  		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 -EINVAL;
  	}
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (res == NULL) {
  		dev_err(&pdev->dev, "no I/O memory defined in platform data\n");
  		return -EINVAL;
  	}
  
  	res = request_mem_region(res->start, resource_size(res), pdev->name);
  	if (res == NULL) {
  		dev_err(&pdev->dev, "failed to request I/O memory\n");
  		return -EBUSY;
  	}
  
  	input_dev = input_allocate_device();
  	if (!input_dev) {
  		dev_err(&pdev->dev, "failed to allocate the input device\n");
  		error = -ENOMEM;
  		goto failed_rel_mem;
  	}
  
  	keypad = kzalloc(sizeof(struct imx_keypad), GFP_KERNEL);
  	if (!keypad) {
  		dev_err(&pdev->dev, "not enough memory for driver data\n");
  		error = -ENOMEM;
  		goto failed_free_input;
  	}
  
  	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);
  
  	keypad->mmio_base = ioremap(res->start, resource_size(res));
  	if (keypad->mmio_base == NULL) {
  		dev_err(&pdev->dev, "failed to remap I/O memory\n");
  		error = -ENOMEM;
  		goto failed_free_priv;
  	}
  
  	keypad->clk = clk_get(&pdev->dev, NULL);
  	if (IS_ERR(keypad->clk)) {
  		dev_err(&pdev->dev, "failed to get keypad clock\n");
  		error = PTR_ERR(keypad->clk);
  		goto failed_unmap;
  	}
  
  	/* Search for rows and cols enabled */
  	for (i = 0; i < keymap_data->keymap_size; i++) {
  		keypad->rows_en_mask |= 1 << KEY_ROW(keymap_data->keymap[i]);
  		keypad->cols_en_mask |= 1 << KEY_COL(keymap_data->keymap[i]);
  	}
  
  	if (keypad->rows_en_mask > ((1 << MAX_MATRIX_KEY_ROWS) - 1) ||
  	    keypad->cols_en_mask > ((1 << MAX_MATRIX_KEY_COLS) - 1)) {
  		dev_err(&pdev->dev,
  			"invalid key data (too many rows or colums)\n");
  		error = -EINVAL;
  		goto failed_clock_put;
  	}
  	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);
  
  	/* 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");
  		goto failed_clock_put;
  	}
  
  	__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 = request_irq(irq, imx_keypad_irq_handler, 0,
  			    pdev->name, keypad);
  	if (error) {
  		dev_err(&pdev->dev, "failed to request IRQ\n");
  		goto failed_clock_put;
  	}
  
  	/* Register the input device */
  	error = input_register_device(input_dev);
  	if (error) {
  		dev_err(&pdev->dev, "failed to register input device\n");
  		goto failed_free_irq;
  	}
  
  	platform_set_drvdata(pdev, keypad);
  	device_init_wakeup(&pdev->dev, 1);
  
  	return 0;
  
  failed_free_irq:
  	free_irq(irq, pdev);
  failed_clock_put:
  	clk_put(keypad->clk);
  failed_unmap:
  	iounmap(keypad->mmio_base);
  failed_free_priv:
  	kfree(keypad);
  failed_free_input:
  	input_free_device(input_dev);
  failed_rel_mem:
  	release_mem_region(res->start, resource_size(res));
  	return error;
  }
  
  static int __devexit imx_keypad_remove(struct platform_device *pdev)
  {
  	struct imx_keypad *keypad = platform_get_drvdata(pdev);
  	struct resource *res;
  
  	dev_dbg(&pdev->dev, ">%s\n", __func__);
  
  	platform_set_drvdata(pdev, NULL);
  
  	input_unregister_device(keypad->input_dev);
  
  	free_irq(keypad->irq, keypad);
  	clk_put(keypad->clk);
  
  	iounmap(keypad->mmio_base);
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	release_mem_region(res->start, resource_size(res));
  
  	kfree(keypad);
  
  	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,
  	},
  	.probe		= imx_keypad_probe,
  	.remove		= __devexit_p(imx_keypad_remove),
  };
  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");
  