/*
   * Touchkey driver for Freescale MPR121 Controllor
   *
   * Copyright (C) 2011 Freescale Semiconductor, Inc.
   * Author: Zhang Jiejing <jiejing.zhang@freescale.com>
   *
   * Based on mcs_touchkey.c
   *
   * 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.
   *
   */
  
  #include <linux/module.h>
  #include <linux/input.h>
  #include <linux/i2c.h>
  #include <linux/slab.h>
  #include <linux/delay.h>
  #include <linux/bitops.h>
  #include <linux/interrupt.h>
  #include <linux/i2c/mpr121_touchkey.h>
  
  /* Register definitions */
  #define ELE_TOUCH_STATUS_0_ADDR	0x0
  #define ELE_TOUCH_STATUS_1_ADDR	0X1
  #define MHD_RISING_ADDR		0x2b
  #define NHD_RISING_ADDR		0x2c
  #define NCL_RISING_ADDR		0x2d
  #define FDL_RISING_ADDR		0x2e
  #define MHD_FALLING_ADDR	0x2f
  #define NHD_FALLING_ADDR	0x30
  #define NCL_FALLING_ADDR	0x31
  #define FDL_FALLING_ADDR	0x32
  #define ELE0_TOUCH_THRESHOLD_ADDR	0x41
  #define ELE0_RELEASE_THRESHOLD_ADDR	0x42
  #define AFE_CONF_ADDR			0x5c
  #define FILTER_CONF_ADDR		0x5d
  
  /*
   * ELECTRODE_CONF_ADDR: This register configures the number of
   * enabled capacitance sensing inputs and its run/suspend mode.
   */
  #define ELECTRODE_CONF_ADDR		0x5e
  #define ELECTRODE_CONF_QUICK_CHARGE	0x80
  #define AUTO_CONFIG_CTRL_ADDR		0x7b
  #define AUTO_CONFIG_USL_ADDR		0x7d
  #define AUTO_CONFIG_LSL_ADDR		0x7e
  #define AUTO_CONFIG_TL_ADDR		0x7f
  
  /* Threshold of touch/release trigger */
  #define TOUCH_THRESHOLD			0x08
  #define RELEASE_THRESHOLD		0x05
  /* Masks for touch and release triggers */
  #define TOUCH_STATUS_MASK		0xfff
  /* MPR121 has 12 keys */
  #define MPR121_MAX_KEY_COUNT		12
  
  struct mpr121_touchkey {
  	struct i2c_client	*client;
  	struct input_dev	*input_dev;
  	unsigned int		key_val;
  	unsigned int		statusbits;
  	unsigned int		keycount;
  	u16			keycodes[MPR121_MAX_KEY_COUNT];
  };
  
  struct mpr121_init_register {
  	int addr;
  	u8 val;
  };
  
  static const struct mpr121_init_register init_reg_table[] = {
  	{ MHD_RISING_ADDR,	0x1 },
  	{ NHD_RISING_ADDR,	0x1 },
  	{ MHD_FALLING_ADDR,	0x1 },
  	{ NHD_FALLING_ADDR,	0x1 },
  	{ NCL_FALLING_ADDR,	0xff },
  	{ FDL_FALLING_ADDR,	0x02 },
  	{ FILTER_CONF_ADDR,	0x04 },
  	{ AFE_CONF_ADDR,	0x0b },
  	{ AUTO_CONFIG_CTRL_ADDR, 0x0b },
  };
  
  static irqreturn_t mpr_touchkey_interrupt(int irq, void *dev_id)
  {
  	struct mpr121_touchkey *mpr121 = dev_id;
  	struct i2c_client *client = mpr121->client;
  	struct input_dev *input = mpr121->input_dev;
  	unsigned int key_num, key_val, pressed;
  	int reg;
  
  	reg = i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_1_ADDR);
  	if (reg < 0) {
  		dev_err(&client->dev, "i2c read error [%d]
  ", reg);
  		goto out;
  	}
  
  	reg <<= 8;
  	reg |= i2c_smbus_read_byte_data(client, ELE_TOUCH_STATUS_0_ADDR);
  	if (reg < 0) {
  		dev_err(&client->dev, "i2c read error [%d]
  ", reg);
  		goto out;
  	}
  
  	reg &= TOUCH_STATUS_MASK;
  	/* use old press bit to figure out which bit changed */
  	key_num = ffs(reg ^ mpr121->statusbits) - 1;
  	pressed = reg & (1 << key_num);
  	mpr121->statusbits = reg;
  
  	key_val = mpr121->keycodes[key_num];
  
  	input_event(input, EV_MSC, MSC_SCAN, key_num);
  	input_report_key(input, key_val, pressed);
  	input_sync(input);
  
  	dev_dbg(&client->dev, "key %d %d %s
  ", key_num, key_val,
  		pressed ? "pressed" : "released");
  
  out:
  	return IRQ_HANDLED;
  }
  
  static int mpr121_phys_init(const struct mpr121_platform_data *pdata,
  				      struct mpr121_touchkey *mpr121,
  				      struct i2c_client *client)
  {
  	const struct mpr121_init_register *reg;
  	unsigned char usl, lsl, tl, eleconf;
  	int i, t, vdd, ret;
  
  	/* Set up touch/release threshold for ele0-ele11 */
  	for (i = 0; i <= MPR121_MAX_KEY_COUNT; i++) {
  		t = ELE0_TOUCH_THRESHOLD_ADDR + (i * 2);
  		ret = i2c_smbus_write_byte_data(client, t, TOUCH_THRESHOLD);
  		if (ret < 0)
  			goto err_i2c_write;
  		ret = i2c_smbus_write_byte_data(client, t + 1,
  						RELEASE_THRESHOLD);
  		if (ret < 0)
  			goto err_i2c_write;
  	}
  
  	/* Set up init register */
  	for (i = 0; i < ARRAY_SIZE(init_reg_table); i++) {
  		reg = &init_reg_table[i];
  		ret = i2c_smbus_write_byte_data(client, reg->addr, reg->val);
  		if (ret < 0)
  			goto err_i2c_write;
  	}
  
  
  	/*
  	 * Capacitance on sensing input varies and needs to be compensated.
  	 * The internal MPR121-auto-configuration can do this if it's
  	 * registers are set properly (based on pdata->vdd_uv).
  	 */
  	vdd = pdata->vdd_uv / 1000;
  	usl = ((vdd - 700) * 256) / vdd;
  	lsl = (usl * 65) / 100;
  	tl = (usl * 90) / 100;
  	ret = i2c_smbus_write_byte_data(client, AUTO_CONFIG_USL_ADDR, usl);
  	ret |= i2c_smbus_write_byte_data(client, AUTO_CONFIG_LSL_ADDR, lsl);
  	ret |= i2c_smbus_write_byte_data(client, AUTO_CONFIG_TL_ADDR, tl);
  
  	/*
  	 * Quick charge bit will let the capacitive charge to ready
  	 * state quickly, or the buttons may not function after system
  	 * boot.
  	 */
  	eleconf = mpr121->keycount | ELECTRODE_CONF_QUICK_CHARGE;
  	ret |= i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR,
  					 eleconf);
  	if (ret != 0)
  		goto err_i2c_write;
  
  	dev_dbg(&client->dev, "set up with %x keys.
  ", mpr121->keycount);
  
  	return 0;
  
  err_i2c_write:
  	dev_err(&client->dev, "i2c write error: %d
  ", ret);
  	return ret;
  }
  
  static int mpr_touchkey_probe(struct i2c_client *client,
  			      const struct i2c_device_id *id)
  {
  	const struct mpr121_platform_data *pdata =
  			dev_get_platdata(&client->dev);
  	struct mpr121_touchkey *mpr121;
  	struct input_dev *input_dev;
  	int error;
  	int i;
  
  	if (!pdata) {
  		dev_err(&client->dev, "no platform data defined
  ");
  		return -EINVAL;
  	}
  
  	if (!pdata->keymap || !pdata->keymap_size) {
  		dev_err(&client->dev, "missing keymap data
  ");
  		return -EINVAL;
  	}
  
  	if (pdata->keymap_size > MPR121_MAX_KEY_COUNT) {
  		dev_err(&client->dev, "too many keys defined
  ");
  		return -EINVAL;
  	}
  
  	if (!client->irq) {
  		dev_err(&client->dev, "irq number should not be zero
  ");
  		return -EINVAL;
  	}
  
  	mpr121 = devm_kzalloc(&client->dev, sizeof(*mpr121),
  			      GFP_KERNEL);
  	if (!mpr121)
  		return -ENOMEM;
  
  	input_dev = devm_input_allocate_device(&client->dev);
  	if (!input_dev)
  		return -ENOMEM;
  
  	mpr121->client = client;
  	mpr121->input_dev = input_dev;
  	mpr121->keycount = pdata->keymap_size;
  
  	input_dev->name = "Freescale MPR121 Touchkey";
  	input_dev->id.bustype = BUS_I2C;
  	input_dev->dev.parent = &client->dev;
  	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
  
  	input_dev->keycode = mpr121->keycodes;
  	input_dev->keycodesize = sizeof(mpr121->keycodes[0]);
  	input_dev->keycodemax = mpr121->keycount;
  
  	for (i = 0; i < pdata->keymap_size; i++) {
  		input_set_capability(input_dev, EV_KEY, pdata->keymap[i]);
  		mpr121->keycodes[i] = pdata->keymap[i];
  	}
  
  	error = mpr121_phys_init(pdata, mpr121, client);
  	if (error) {
  		dev_err(&client->dev, "Failed to init register
  ");
  		return error;
  	}
  
  	error = devm_request_threaded_irq(&client->dev, client->irq, NULL,
  				     mpr_touchkey_interrupt,
  				     IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
  				     client->dev.driver->name, mpr121);
  	if (error) {
  		dev_err(&client->dev, "Failed to register interrupt
  ");
  		return error;
  	}
  
  	error = input_register_device(input_dev);
  	if (error)
  		return error;
  
  	i2c_set_clientdata(client, mpr121);
  	device_init_wakeup(&client->dev, pdata->wakeup);
  
  	return 0;
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int mpr_suspend(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  
  	if (device_may_wakeup(&client->dev))
  		enable_irq_wake(client->irq);
  
  	i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR, 0x00);
  
  	return 0;
  }
  
  static int mpr_resume(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct mpr121_touchkey *mpr121 = i2c_get_clientdata(client);
  
  	if (device_may_wakeup(&client->dev))
  		disable_irq_wake(client->irq);
  
  	i2c_smbus_write_byte_data(client, ELECTRODE_CONF_ADDR,
  				  mpr121->keycount);
  
  	return 0;
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(mpr121_touchkey_pm_ops, mpr_suspend, mpr_resume);
  
  static const struct i2c_device_id mpr121_id[] = {
  	{ "mpr121_touchkey", 0 },
  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, mpr121_id);
  
  static struct i2c_driver mpr_touchkey_driver = {
  	.driver = {
  		.name	= "mpr121",
  		.pm	= &mpr121_touchkey_pm_ops,
  	},
  	.id_table	= mpr121_id,
  	.probe		= mpr_touchkey_probe,
  };
  
  module_i2c_driver(mpr_touchkey_driver);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Zhang Jiejing <jiejing.zhang@freescale.com>");
  MODULE_DESCRIPTION("Touch Key driver for Freescale MPR121 Chip");