/*
   * Texas Instruments TNETV107X Keypad Driver
   *
   * Copyright (C) 2010 Texas Instruments
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation version 2.
   *
   * This program is distributed "as is" WITHOUT ANY WARRANTY of any
   * kind, whether express or implied; without even the implied warranty
   * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  
  #include <linux/kernel.h>
  #include <linux/err.h>
  #include <linux/errno.h>
  #include <linux/input.h>
  #include <linux/platform_device.h>
  #include <linux/interrupt.h>
  #include <linux/slab.h>
  #include <linux/delay.h>
  #include <linux/io.h>
  #include <linux/clk.h>
  #include <linux/input/matrix_keypad.h>
  #include <linux/module.h>
  
  #define BITS(x)			(BIT(x) - 1)
  
  #define KEYPAD_ROWS		9
  #define KEYPAD_COLS		9
  
  #define DEBOUNCE_MIN		0x400ul
  #define DEBOUNCE_MAX		0x3ffffffful
  
  struct keypad_regs {
  	u32	rev;
  	u32	mode;
  	u32	mask;
  	u32	pol;
  	u32	dclock;
  	u32	rclock;
  	u32	stable_cnt;
  	u32	in_en;
  	u32	out;
  	u32	out_en;
  	u32	in;
  	u32	lock;
  	u32	pres[3];
  };
  
  #define keypad_read(kp, reg)		__raw_readl(&(kp)->regs->reg)
  #define keypad_write(kp, reg, val)	__raw_writel(val, &(kp)->regs->reg)
  
  struct keypad_data {
  	struct input_dev		*input_dev;
  	struct resource			*res;
  	struct keypad_regs __iomem	*regs;
  	struct clk			*clk;
  	struct device			*dev;
  	spinlock_t			lock;
  	int				irq_press;
  	int				irq_release;
  	int				rows, cols, row_shift;
  	int				debounce_ms, active_low;
  	u32				prev_keys[3];
  	unsigned short			keycodes[];
  };
  
  static irqreturn_t keypad_irq(int irq, void *data)
  {
  	struct keypad_data *kp = data;
  	int i, bit, val, row, col, code;
  	unsigned long flags;
  	u32 curr_keys[3];
  	u32 change;
  
  	spin_lock_irqsave(&kp->lock, flags);
  
  	memset(curr_keys, 0, sizeof(curr_keys));
  	if (irq == kp->irq_press)
  		for (i = 0; i < 3; i++)
  			curr_keys[i] = keypad_read(kp, pres[i]);
  
  	for (i = 0; i < 3; i++) {
  		change = curr_keys[i] ^ kp->prev_keys[i];
  
  		while (change) {
  			bit     = fls(change) - 1;
  			change ^= BIT(bit);
  			val     = curr_keys[i] & BIT(bit);
  			bit    += i * 32;
  			row     = bit / KEYPAD_COLS;
  			col     = bit % KEYPAD_COLS;
  
  			code = MATRIX_SCAN_CODE(row, col, kp->row_shift);
  			input_event(kp->input_dev, EV_MSC, MSC_SCAN, code);
  			input_report_key(kp->input_dev, kp->keycodes[code],
  					 val);
  		}
  	}
  	input_sync(kp->input_dev);
  	memcpy(kp->prev_keys, curr_keys, sizeof(curr_keys));
  
  	if (irq == kp->irq_press)
  		keypad_write(kp, lock, 0); /* Allow hardware updates */
  
  	spin_unlock_irqrestore(&kp->lock, flags);
  
  	return IRQ_HANDLED;
  }
  
  static int keypad_start(struct input_dev *dev)
  {
  	struct keypad_data *kp = input_get_drvdata(dev);
  	unsigned long mask, debounce, clk_rate_khz;
  	unsigned long flags;
  
  	clk_enable(kp->clk);
  	clk_rate_khz = clk_get_rate(kp->clk) / 1000;
  
  	spin_lock_irqsave(&kp->lock, flags);
  
  	/* Initialize device registers */
  	keypad_write(kp, mode, 0);
  
  	mask  = BITS(kp->rows) << KEYPAD_COLS;
  	mask |= BITS(kp->cols);
  	keypad_write(kp, mask, ~mask);
  
  	keypad_write(kp, pol, kp->active_low ? 0 : 0x3ffff);
  	keypad_write(kp, stable_cnt, 3);
  
  	debounce = kp->debounce_ms * clk_rate_khz;
  	debounce = clamp(debounce, DEBOUNCE_MIN, DEBOUNCE_MAX);
  	keypad_write(kp, dclock, debounce);
  	keypad_write(kp, rclock, 4 * debounce);
  
  	keypad_write(kp, in_en, 1);
  
  	spin_unlock_irqrestore(&kp->lock, flags);
  
  	return 0;
  }
  
  static void keypad_stop(struct input_dev *dev)
  {
  	struct keypad_data *kp = input_get_drvdata(dev);
  
  	synchronize_irq(kp->irq_press);
  	synchronize_irq(kp->irq_release);
  	clk_disable(kp->clk);
  }
  
  static int keypad_probe(struct platform_device *pdev)
  {
  	const struct matrix_keypad_platform_data *pdata;
  	const struct matrix_keymap_data *keymap_data;
  	struct device *dev = &pdev->dev;
  	struct keypad_data *kp;
  	int error = 0, sz, row_shift;
  	u32 rev = 0;
  
  	pdata = dev_get_platdata(&pdev->dev);
  	if (!pdata) {
  		dev_err(dev, "cannot find device data
  ");
  		return -EINVAL;
  	}
  
  	keymap_data = pdata->keymap_data;
  	if (!keymap_data) {
  		dev_err(dev, "cannot find keymap data
  ");
  		return -EINVAL;
  	}
  
  	row_shift = get_count_order(pdata->num_col_gpios);
  	sz  = offsetof(struct keypad_data, keycodes);
  	sz += (pdata->num_row_gpios << row_shift) * sizeof(kp->keycodes[0]);
  	kp = kzalloc(sz, GFP_KERNEL);
  	if (!kp) {
  		dev_err(dev, "cannot allocate device info
  ");
  		return -ENOMEM;
  	}
  
  	kp->dev  = dev;
  	kp->rows = pdata->num_row_gpios;
  	kp->cols = pdata->num_col_gpios;
  	kp->row_shift = row_shift;
  	platform_set_drvdata(pdev, kp);
  	spin_lock_init(&kp->lock);
  
  	kp->irq_press   = platform_get_irq_byname(pdev, "press");
  	kp->irq_release = platform_get_irq_byname(pdev, "release");
  	if (kp->irq_press < 0 || kp->irq_release < 0) {
  		dev_err(dev, "cannot determine device interrupts
  ");
  		error = -ENODEV;
  		goto error_res;
  	}
  
  	kp->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!kp->res) {
  		dev_err(dev, "cannot determine register area
  ");
  		error = -ENODEV;
  		goto error_res;
  	}
  
  	if (!request_mem_region(kp->res->start, resource_size(kp->res),
  				pdev->name)) {
  		dev_err(dev, "cannot claim register memory
  ");
  		kp->res = NULL;
  		error = -EINVAL;
  		goto error_res;
  	}
  
  	kp->regs = ioremap(kp->res->start, resource_size(kp->res));
  	if (!kp->regs) {
  		dev_err(dev, "cannot map register memory
  ");
  		error = -ENOMEM;
  		goto error_map;
  	}
  
  	kp->clk = clk_get(dev, NULL);
  	if (IS_ERR(kp->clk)) {
  		dev_err(dev, "cannot claim device clock
  ");
  		error = PTR_ERR(kp->clk);
  		goto error_clk;
  	}
  
  	error = request_threaded_irq(kp->irq_press, NULL, keypad_irq,
  				     IRQF_ONESHOT, dev_name(dev), kp);
  	if (error < 0) {
  		dev_err(kp->dev, "Could not allocate keypad press key irq
  ");
  		goto error_irq_press;
  	}
  
  	error = request_threaded_irq(kp->irq_release, NULL, keypad_irq,
  				     IRQF_ONESHOT, dev_name(dev), kp);
  	if (error < 0) {
  		dev_err(kp->dev, "Could not allocate keypad release key irq
  ");
  		goto error_irq_release;
  	}
  
  	kp->input_dev = input_allocate_device();
  	if (!kp->input_dev) {
  		dev_err(dev, "cannot allocate input device
  ");
  		error = -ENOMEM;
  		goto error_input;
  	}
  
  	kp->input_dev->name	  = pdev->name;
  	kp->input_dev->dev.parent = &pdev->dev;
  	kp->input_dev->open	  = keypad_start;
  	kp->input_dev->close	  = keypad_stop;
  
  	clk_enable(kp->clk);
  	rev = keypad_read(kp, rev);
  	kp->input_dev->id.bustype = BUS_HOST;
  	kp->input_dev->id.product = ((rev >>  8) & 0x07);
  	kp->input_dev->id.version = ((rev >> 16) & 0xfff);
  	clk_disable(kp->clk);
  
  	error = matrix_keypad_build_keymap(keymap_data, NULL,
  					   kp->rows, kp->cols,
  					   kp->keycodes, kp->input_dev);
  	if (error) {
  		dev_err(dev, "Failed to build keymap
  ");
  		goto error_reg;
  	}
  
  	if (!pdata->no_autorepeat)
  		kp->input_dev->evbit[0] |= BIT_MASK(EV_REP);
  	input_set_capability(kp->input_dev, EV_MSC, MSC_SCAN);
  
  	input_set_drvdata(kp->input_dev, kp);
  
  	error = input_register_device(kp->input_dev);
  	if (error < 0) {
  		dev_err(dev, "Could not register input device
  ");
  		goto error_reg;
  	}
  
  	return 0;
  
  
  error_reg:
  	input_free_device(kp->input_dev);
  error_input:
  	free_irq(kp->irq_release, kp);
  error_irq_release:
  	free_irq(kp->irq_press, kp);
  error_irq_press:
  	clk_put(kp->clk);
  error_clk:
  	iounmap(kp->regs);
  error_map:
  	release_mem_region(kp->res->start, resource_size(kp->res));
  error_res:
  	kfree(kp);
  	return error;
  }
  
  static int keypad_remove(struct platform_device *pdev)
  {
  	struct keypad_data *kp = platform_get_drvdata(pdev);
  
  	free_irq(kp->irq_press, kp);
  	free_irq(kp->irq_release, kp);
  	input_unregister_device(kp->input_dev);
  	clk_put(kp->clk);
  	iounmap(kp->regs);
  	release_mem_region(kp->res->start, resource_size(kp->res));
  	kfree(kp);
  
  	return 0;
  }
  
  static struct platform_driver keypad_driver = {
  	.probe		= keypad_probe,
  	.remove		= keypad_remove,
  	.driver.name	= "tnetv107x-keypad",
  	.driver.owner	= THIS_MODULE,
  };
  module_platform_driver(keypad_driver);
  
  MODULE_AUTHOR("Cyril Chemparathy");
  MODULE_DESCRIPTION("TNETV107X Keypad Driver");
  MODULE_ALIAS("platform:tnetv107x-keypad");
  MODULE_LICENSE("GPL");