/*
   * drivers/input/touchscreen/tsc2007.c
   *
   * Copyright (c) 2008 MtekVision Co., Ltd.
   *	Kwangwoo Lee <kwlee@mtekvision.com>
   *
   * Using code from:
   *  - ads7846.c
   *	Copyright (c) 2005 David Brownell
   *	Copyright (c) 2006 Nokia Corporation
   *  - corgi_ts.c
   *	Copyright (C) 2004-2005 Richard Purdie
   *  - omap_ts.[hc], ads7846.h, ts_osk.c
   *	Copyright (C) 2002 MontaVista Software
   *	Copyright (C) 2004 Texas Instruments
   *	Copyright (C) 2005 Dirk Behme
   *
   *  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/slab.h>
  #include <linux/input.h>
  #include <linux/interrupt.h>
  #include <linux/i2c.h>
  #include <linux/i2c/tsc2007.h>
  #include <linux/of_device.h>
  #include <linux/of.h>
  #include <linux/of_gpio.h>
  
  #define TSC2007_MEASURE_TEMP0		(0x0 << 4)
  #define TSC2007_MEASURE_AUX		(0x2 << 4)
  #define TSC2007_MEASURE_TEMP1		(0x4 << 4)
  #define TSC2007_ACTIVATE_XN		(0x8 << 4)
  #define TSC2007_ACTIVATE_YN		(0x9 << 4)
  #define TSC2007_ACTIVATE_YP_XN		(0xa << 4)
  #define TSC2007_SETUP			(0xb << 4)
  #define TSC2007_MEASURE_X		(0xc << 4)
  #define TSC2007_MEASURE_Y		(0xd << 4)
  #define TSC2007_MEASURE_Z1		(0xe << 4)
  #define TSC2007_MEASURE_Z2		(0xf << 4)
  
  #define TSC2007_POWER_OFF_IRQ_EN	(0x0 << 2)
  #define TSC2007_ADC_ON_IRQ_DIS0		(0x1 << 2)
  #define TSC2007_ADC_OFF_IRQ_EN		(0x2 << 2)
  #define TSC2007_ADC_ON_IRQ_DIS1		(0x3 << 2)
  
  #define TSC2007_12BIT			(0x0 << 1)
  #define TSC2007_8BIT			(0x1 << 1)
  
  #define	MAX_12BIT			((1 << 12) - 1)
  
  #define ADC_ON_12BIT	(TSC2007_12BIT | TSC2007_ADC_ON_IRQ_DIS0)
  
  #define READ_Y		(ADC_ON_12BIT | TSC2007_MEASURE_Y)
  #define READ_Z1		(ADC_ON_12BIT | TSC2007_MEASURE_Z1)
  #define READ_Z2		(ADC_ON_12BIT | TSC2007_MEASURE_Z2)
  #define READ_X		(ADC_ON_12BIT | TSC2007_MEASURE_X)
  #define PWRDOWN		(TSC2007_12BIT | TSC2007_POWER_OFF_IRQ_EN)
  
  struct ts_event {
  	u16	x;
  	u16	y;
  	u16	z1, z2;
  };
  
  struct tsc2007 {
  	struct input_dev	*input;
  	char			phys[32];
  
  	struct i2c_client	*client;
  
  	u16			model;
  	u16			x_plate_ohms;
  	u16			max_rt;
  	unsigned long		poll_period;
  	int			fuzzx;
  	int			fuzzy;
  	int			fuzzz;
  
  	unsigned		gpio;
  	int			irq;
  
  	wait_queue_head_t	wait;
  	bool			stopped;
  
  	int			(*get_pendown_state)(struct device *);
  	void			(*clear_penirq)(void);
  };
  
  static inline int tsc2007_xfer(struct tsc2007 *tsc, u8 cmd)
  {
  	s32 data;
  	u16 val;
  
  	data = i2c_smbus_read_word_data(tsc->client, cmd);
  	if (data < 0) {
  		dev_err(&tsc->client->dev, "i2c io error: %d
  ", data);
  		return data;
  	}
  
  	/* The protocol and raw data format from i2c interface:
  	 * S Addr Wr [A] Comm [A] S Addr Rd [A] [DataLow] A [DataHigh] NA P
  	 * Where DataLow has [D11-D4], DataHigh has [D3-D0 << 4 | Dummy 4bit].
  	 */
  	val = swab16(data) >> 4;
  
  	dev_dbg(&tsc->client->dev, "data: 0x%x, val: 0x%x
  ", data, val);
  
  	return val;
  }
  
  static void tsc2007_read_values(struct tsc2007 *tsc, struct ts_event *tc)
  {
  	/* y- still on; turn on only y+ (and ADC) */
  	tc->y = tsc2007_xfer(tsc, READ_Y);
  
  	/* turn y- off, x+ on, then leave in lowpower */
  	tc->x = tsc2007_xfer(tsc, READ_X);
  
  	/* turn y+ off, x- on; we'll use formula #1 */
  	tc->z1 = tsc2007_xfer(tsc, READ_Z1);
  	tc->z2 = tsc2007_xfer(tsc, READ_Z2);
  
  	/* Prepare for next touch reading - power down ADC, enable PENIRQ */
  	tsc2007_xfer(tsc, PWRDOWN);
  }
  
  static u32 tsc2007_calculate_pressure(struct tsc2007 *tsc, struct ts_event *tc)
  {
  	u32 rt = 0;
  
  	/* range filtering */
  	if (tc->x == MAX_12BIT)
  		tc->x = 0;
  
  	if (likely(tc->x && tc->z1)) {
  		/* compute touch pressure resistance using equation #1 */
  		rt = tc->z2 - tc->z1;
  		rt *= tc->x;
  		rt *= tsc->x_plate_ohms;
  		rt /= tc->z1;
  		rt = (rt + 2047) >> 12;
  	}
  
  	return rt;
  }
  
  static bool tsc2007_is_pen_down(struct tsc2007 *ts)
  {
  	/*
  	 * NOTE: We can't rely on the pressure to determine the pen down
  	 * state, even though this controller has a pressure sensor.
  	 * The pressure value can fluctuate for quite a while after
  	 * lifting the pen and in some cases may not even settle at the
  	 * expected value.
  	 *
  	 * The only safe way to check for the pen up condition is in the
  	 * work function by reading the pen signal state (it's a GPIO
  	 * and IRQ). Unfortunately such callback is not always available,
  	 * in that case we assume that the pen is down and expect caller
  	 * to fall back on the pressure reading.
  	 */
  
  	if (!ts->get_pendown_state)
  		return true;
  
  	return ts->get_pendown_state(&ts->client->dev);
  }
  
  static irqreturn_t tsc2007_soft_irq(int irq, void *handle)
  {
  	struct tsc2007 *ts = handle;
  	struct input_dev *input = ts->input;
  	struct ts_event tc;
  	u32 rt;
  
  	while (!ts->stopped && tsc2007_is_pen_down(ts)) {
  
  		/* pen is down, continue with the measurement */
  		tsc2007_read_values(ts, &tc);
  
  		rt = tsc2007_calculate_pressure(ts, &tc);
  
  		if (!rt && !ts->get_pendown_state) {
  			/*
  			 * If pressure reported is 0 and we don't have
  			 * callback to check pendown state, we have to
  			 * assume that pen was lifted up.
  			 */
  			break;
  		}
  
  		if (rt <= ts->max_rt) {
  			dev_dbg(&ts->client->dev,
  				"DOWN point(%4d,%4d), pressure (%4u)
  ",
  				tc.x, tc.y, rt);
  
  			input_report_key(input, BTN_TOUCH, 1);
  			input_report_abs(input, ABS_X, tc.x);
  			input_report_abs(input, ABS_Y, tc.y);
  			input_report_abs(input, ABS_PRESSURE, rt);
  
  			input_sync(input);
  
  		} else {
  			/*
  			 * Sample found inconsistent by debouncing or pressure is
  			 * beyond the maximum. Don't report it to user space,
  			 * repeat at least once more the measurement.
  			 */
  			dev_dbg(&ts->client->dev, "ignored pressure %d
  ", rt);
  		}
  
  		wait_event_timeout(ts->wait, ts->stopped,
  				   msecs_to_jiffies(ts->poll_period));
  	}
  
  	dev_dbg(&ts->client->dev, "UP
  ");
  
  	input_report_key(input, BTN_TOUCH, 0);
  	input_report_abs(input, ABS_PRESSURE, 0);
  	input_sync(input);
  
  	if (ts->clear_penirq)
  		ts->clear_penirq();
  
  	return IRQ_HANDLED;
  }
  
  static irqreturn_t tsc2007_hard_irq(int irq, void *handle)
  {
  	struct tsc2007 *ts = handle;
  
  	if (tsc2007_is_pen_down(ts))
  		return IRQ_WAKE_THREAD;
  
  	if (ts->clear_penirq)
  		ts->clear_penirq();
  
  	return IRQ_HANDLED;
  }
  
  static void tsc2007_stop(struct tsc2007 *ts)
  {
  	ts->stopped = true;
  	mb();
  	wake_up(&ts->wait);
  
  	disable_irq(ts->irq);
  }
  
  static int tsc2007_open(struct input_dev *input_dev)
  {
  	struct tsc2007 *ts = input_get_drvdata(input_dev);
  	int err;
  
  	ts->stopped = false;
  	mb();
  
  	enable_irq(ts->irq);
  
  	/* Prepare for touch readings - power down ADC and enable PENIRQ */
  	err = tsc2007_xfer(ts, PWRDOWN);
  	if (err < 0) {
  		tsc2007_stop(ts);
  		return err;
  	}
  
  	return 0;
  }
  
  static void tsc2007_close(struct input_dev *input_dev)
  {
  	struct tsc2007 *ts = input_get_drvdata(input_dev);
  
  	tsc2007_stop(ts);
  }
  
  #ifdef CONFIG_OF
  static int tsc2007_get_pendown_state_gpio(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct tsc2007 *ts = i2c_get_clientdata(client);
  
  	return !gpio_get_value(ts->gpio);
  }
  
  static int tsc2007_probe_dt(struct i2c_client *client, struct tsc2007 *ts)
  {
  	struct device_node *np = client->dev.of_node;
  	u32 val32;
  	u64 val64;
  
  	if (!np) {
  		dev_err(&client->dev, "missing device tree data
  ");
  		return -EINVAL;
  	}
  
  	if (!of_property_read_u32(np, "ti,max-rt", &val32))
  		ts->max_rt = val32;
  	else
  		ts->max_rt = MAX_12BIT;
  
  	if (!of_property_read_u32(np, "ti,fuzzx", &val32))
  		ts->fuzzx = val32;
  
  	if (!of_property_read_u32(np, "ti,fuzzy", &val32))
  		ts->fuzzy = val32;
  
  	if (!of_property_read_u32(np, "ti,fuzzz", &val32))
  		ts->fuzzz = val32;
  
  	if (!of_property_read_u64(np, "ti,poll-period", &val64))
  		ts->poll_period = val64;
  	else
  		ts->poll_period = 1;
  
  	if (!of_property_read_u32(np, "ti,x-plate-ohms", &val32)) {
  		ts->x_plate_ohms = val32;
  	} else {
  		dev_err(&client->dev, "missing ti,x-plate-ohms devicetree property.");
  		return -EINVAL;
  	}
  
  	ts->gpio = of_get_gpio(np, 0);
  	if (gpio_is_valid(ts->gpio))
  		ts->get_pendown_state = tsc2007_get_pendown_state_gpio;
  	else
  		dev_warn(&client->dev,
  			 "GPIO not specified in DT (of_get_gpio returned %d)
  ",
  			 ts->gpio);
  
  	return 0;
  }
  #else
  static int tsc2007_probe_dt(struct i2c_client *client, struct tsc2007 *ts)
  {
  	dev_err(&client->dev, "platform data is required!
  ");
  	return -EINVAL;
  }
  #endif
  
  static int tsc2007_probe_pdev(struct i2c_client *client, struct tsc2007 *ts,
  			      const struct tsc2007_platform_data *pdata,
  			      const struct i2c_device_id *id)
  {
  	ts->model             = pdata->model;
  	ts->x_plate_ohms      = pdata->x_plate_ohms;
  	ts->max_rt            = pdata->max_rt ? : MAX_12BIT;
  	ts->poll_period       = pdata->poll_period ? : 1;
  	ts->get_pendown_state = pdata->get_pendown_state;
  	ts->clear_penirq      = pdata->clear_penirq;
  	ts->fuzzx             = pdata->fuzzx;
  	ts->fuzzy             = pdata->fuzzy;
  	ts->fuzzz             = pdata->fuzzz;
  
  	if (pdata->x_plate_ohms == 0) {
  		dev_err(&client->dev, "x_plate_ohms is not set up in platform data");
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static void tsc2007_call_exit_platform_hw(void *data)
  {
  	struct device *dev = data;
  	const struct tsc2007_platform_data *pdata = dev_get_platdata(dev);
  
  	pdata->exit_platform_hw();
  }
  
  static int tsc2007_probe(struct i2c_client *client,
  			 const struct i2c_device_id *id)
  {
  	const struct tsc2007_platform_data *pdata = dev_get_platdata(&client->dev);
  	struct tsc2007 *ts;
  	struct input_dev *input_dev;
  	int err;
  
  	if (!i2c_check_functionality(client->adapter,
  				     I2C_FUNC_SMBUS_READ_WORD_DATA))
  		return -EIO;
  
  	ts = devm_kzalloc(&client->dev, sizeof(struct tsc2007), GFP_KERNEL);
  	if (!ts)
  		return -ENOMEM;
  
  	if (pdata)
  		err = tsc2007_probe_pdev(client, ts, pdata, id);
  	else
  		err = tsc2007_probe_dt(client, ts);
  	if (err)
  		return err;
  
  	input_dev = devm_input_allocate_device(&client->dev);
  	if (!input_dev)
  		return -ENOMEM;
  
  	i2c_set_clientdata(client, ts);
  
  	ts->client = client;
  	ts->irq = client->irq;
  	ts->input = input_dev;
  	init_waitqueue_head(&ts->wait);
  
  	snprintf(ts->phys, sizeof(ts->phys),
  		 "%s/input0", dev_name(&client->dev));
  
  	input_dev->name = "TSC2007 Touchscreen";
  	input_dev->phys = ts->phys;
  	input_dev->id.bustype = BUS_I2C;
  
  	input_dev->open = tsc2007_open;
  	input_dev->close = tsc2007_close;
  
  	input_set_drvdata(input_dev, ts);
  
  	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
  	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
  
  	input_set_abs_params(input_dev, ABS_X, 0, MAX_12BIT, ts->fuzzx, 0);
  	input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, ts->fuzzy, 0);
  	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT,
  			     ts->fuzzz, 0);
  
  	if (pdata) {
  		if (pdata->exit_platform_hw) {
  			err = devm_add_action(&client->dev,
  					      tsc2007_call_exit_platform_hw,
  					      &client->dev);
  			if (err) {
  				dev_err(&client->dev,
  					"Failed to register exit_platform_hw action, %d
  ",
  					err);
  				return err;
  			}
  		}
  
  		if (pdata->init_platform_hw)
  			pdata->init_platform_hw();
  	}
  
  	err = devm_request_threaded_irq(&client->dev, ts->irq,
  					tsc2007_hard_irq, tsc2007_soft_irq,
  					IRQF_ONESHOT,
  					client->dev.driver->name, ts);
  	if (err) {
  		dev_err(&client->dev, "Failed to request irq %d: %d
  ",
  			ts->irq, err);
  		return err;
  	}
  
  	tsc2007_stop(ts);
  
  	err = input_register_device(input_dev);
  	if (err) {
  		dev_err(&client->dev,
  			"Failed to register input device: %d
  ", err);
  		return err;
  	}
  
  	return 0;
  }
  
  static const struct i2c_device_id tsc2007_idtable[] = {
  	{ "tsc2007", 0 },
  	{ }
  };
  
  MODULE_DEVICE_TABLE(i2c, tsc2007_idtable);
  
  #ifdef CONFIG_OF
  static const struct of_device_id tsc2007_of_match[] = {
  	{ .compatible = "ti,tsc2007" },
  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, tsc2007_of_match);
  #endif
  
  static struct i2c_driver tsc2007_driver = {
  	.driver = {
  		.owner	= THIS_MODULE,
  		.name	= "tsc2007",
  		.of_match_table = of_match_ptr(tsc2007_of_match),
  	},
  	.id_table	= tsc2007_idtable,
  	.probe		= tsc2007_probe,
  };
  
  module_i2c_driver(tsc2007_driver);
  
  MODULE_AUTHOR("Kwangwoo Lee <kwlee@mtekvision.com>");
  MODULE_DESCRIPTION("TSC2007 TouchScreen Driver");
  MODULE_LICENSE("GPL");