/*
   * Texas Instruments TNETV107X Touchscreen 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/module.h>
  #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/ctype.h>
  #include <linux/io.h>
  #include <linux/clk.h>
  
  #include <mach/tnetv107x.h>
  
  #define TSC_PENUP_POLL		(HZ / 5)
  #define IDLE_TIMEOUT		100 /* msec */
  
  /*
   * The first and last samples of a touch interval are usually garbage and need
   * to be filtered out with these devices.  The following definitions control
   * the number of samples skipped.
   */
  #define TSC_HEAD_SKIP		1
  #define TSC_TAIL_SKIP		1
  #define TSC_SKIP		(TSC_HEAD_SKIP + TSC_TAIL_SKIP + 1)
  #define TSC_SAMPLES		(TSC_SKIP + 1)
  
  /* Register Offsets */
  struct tsc_regs {
  	u32	rev;
  	u32	tscm;
  	u32	bwcm;
  	u32	swc;
  	u32	adcchnl;
  	u32	adcdata;
  	u32	chval[4];
  };
  
  /* TSC Mode Configuration Register (tscm) bits */
  #define WMODE		BIT(0)
  #define TSKIND		BIT(1)
  #define ZMEASURE_EN	BIT(2)
  #define IDLE		BIT(3)
  #define TSC_EN		BIT(4)
  #define STOP		BIT(5)
  #define ONE_SHOT	BIT(6)
  #define SINGLE		BIT(7)
  #define AVG		BIT(8)
  #define AVGNUM(x)	(((x) & 0x03) <<  9)
  #define PVSTC(x)	(((x) & 0x07) << 11)
  #define PON		BIT(14)
  #define PONBG		BIT(15)
  #define AFERST		BIT(16)
  
  /* ADC DATA Capture Register bits */
  #define DATA_VALID	BIT(16)
  
  /* Register Access Macros */
  #define tsc_read(ts, reg)		__raw_readl(&(ts)->regs->reg)
  #define tsc_write(ts, reg, val)		__raw_writel(val, &(ts)->regs->reg);
  #define tsc_set_bits(ts, reg, val)	\
  	tsc_write(ts, reg, tsc_read(ts, reg) | (val))
  #define tsc_clr_bits(ts, reg, val)	\
  	tsc_write(ts, reg, tsc_read(ts, reg) & ~(val))
  
  struct sample {
  	int x, y, p;
  };
  
  struct tsc_data {
  	struct input_dev		*input_dev;
  	struct resource			*res;
  	struct tsc_regs __iomem		*regs;
  	struct timer_list		timer;
  	spinlock_t			lock;
  	struct clk			*clk;
  	struct device			*dev;
  	int				sample_count;
  	struct sample			samples[TSC_SAMPLES];
  	int				tsc_irq;
  };
  
  static int tsc_read_sample(struct tsc_data *ts, struct sample* sample)
  {
  	int	x, y, z1, z2, t, p = 0;
  	u32	val;
  
  	val = tsc_read(ts, chval[0]);
  	if (val & DATA_VALID)
  		x = val & 0xffff;
  	else
  		return -EINVAL;
  
  	y  = tsc_read(ts, chval[1]) & 0xffff;
  	z1 = tsc_read(ts, chval[2]) & 0xffff;
  	z2 = tsc_read(ts, chval[3]) & 0xffff;
  
  	if (z1) {
  		t = ((600 * x) * (z2 - z1));
  		p = t / (u32) (z1 << 12);
  		if (p < 0)
  			p = 0;
  	}
  
  	sample->x  = x;
  	sample->y  = y;
  	sample->p  = p;
  
  	return 0;
  }
  
  static void tsc_poll(unsigned long data)
  {
  	struct tsc_data *ts = (struct tsc_data *)data;
  	unsigned long flags;
  	int i, val, x, y, p;
  
  	spin_lock_irqsave(&ts->lock, flags);
  
  	if (ts->sample_count >= TSC_SKIP) {
  		input_report_abs(ts->input_dev, ABS_PRESSURE, 0);
  		input_report_key(ts->input_dev, BTN_TOUCH, 0);
  		input_sync(ts->input_dev);
  	} else if (ts->sample_count > 0) {
  		/*
  		 * A touch event lasted less than our skip count.  Salvage and
  		 * report anyway.
  		 */
  		for (i = 0, val = 0; i < ts->sample_count; i++)
  			val += ts->samples[i].x;
  		x = val / ts->sample_count;
  
  		for (i = 0, val = 0; i < ts->sample_count; i++)
  			val += ts->samples[i].y;
  		y = val / ts->sample_count;
  
  		for (i = 0, val = 0; i < ts->sample_count; i++)
  			val += ts->samples[i].p;
  		p = val / ts->sample_count;
  
  		input_report_abs(ts->input_dev, ABS_X, x);
  		input_report_abs(ts->input_dev, ABS_Y, y);
  		input_report_abs(ts->input_dev, ABS_PRESSURE, p);
  		input_report_key(ts->input_dev, BTN_TOUCH, 1);
  		input_sync(ts->input_dev);
  	}
  
  	ts->sample_count = 0;
  
  	spin_unlock_irqrestore(&ts->lock, flags);
  }
  
  static irqreturn_t tsc_irq(int irq, void *dev_id)
  {
  	struct tsc_data *ts = (struct tsc_data *)dev_id;
  	struct sample *sample;
  	int index;
  
  	spin_lock(&ts->lock);
  
  	index = ts->sample_count % TSC_SAMPLES;
  	sample = &ts->samples[index];
  	if (tsc_read_sample(ts, sample) < 0)
  		goto out;
  
  	if (++ts->sample_count >= TSC_SKIP) {
  		index = (ts->sample_count - TSC_TAIL_SKIP - 1) % TSC_SAMPLES;
  		sample = &ts->samples[index];
  
  		input_report_abs(ts->input_dev, ABS_X, sample->x);
  		input_report_abs(ts->input_dev, ABS_Y, sample->y);
  		input_report_abs(ts->input_dev, ABS_PRESSURE, sample->p);
  		if (ts->sample_count == TSC_SKIP)
  			input_report_key(ts->input_dev, BTN_TOUCH, 1);
  		input_sync(ts->input_dev);
  	}
  	mod_timer(&ts->timer, jiffies + TSC_PENUP_POLL);
  out:
  	spin_unlock(&ts->lock);
  	return IRQ_HANDLED;
  }
  
  static int tsc_start(struct input_dev *dev)
  {
  	struct tsc_data *ts = input_get_drvdata(dev);
  	unsigned long timeout = jiffies + msecs_to_jiffies(IDLE_TIMEOUT);
  	u32 val;
  
  	clk_enable(ts->clk);
  
  	/* Go to idle mode, before any initialization */
  	while (time_after(timeout, jiffies)) {
  		if (tsc_read(ts, tscm) & IDLE)
  			break;
  	}
  
  	if (time_before(timeout, jiffies)) {
  		dev_warn(ts->dev, "timeout waiting for idle
  ");
  		clk_disable(ts->clk);
  		return -EIO;
  	}
  
  	/* Configure TSC Control register*/
  	val = (PONBG | PON | PVSTC(4) | ONE_SHOT | ZMEASURE_EN);
  	tsc_write(ts, tscm, val);
  
  	/* Bring TSC out of reset: Clear AFE reset bit */
  	val &= ~(AFERST);
  	tsc_write(ts, tscm, val);
  
  	/* Configure all pins for hardware control*/
  	tsc_write(ts, bwcm, 0);
  
  	/* Finally enable the TSC */
  	tsc_set_bits(ts, tscm, TSC_EN);
  
  	return 0;
  }
  
  static void tsc_stop(struct input_dev *dev)
  {
  	struct tsc_data *ts = input_get_drvdata(dev);
  
  	tsc_clr_bits(ts, tscm, TSC_EN);
  	synchronize_irq(ts->tsc_irq);
  	del_timer_sync(&ts->timer);
  	clk_disable(ts->clk);
  }
  
  static int tsc_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct tsc_data *ts;
  	int error = 0;
  	u32 rev = 0;
  
  	ts = kzalloc(sizeof(struct tsc_data), GFP_KERNEL);
  	if (!ts) {
  		dev_err(dev, "cannot allocate device info
  ");
  		return -ENOMEM;
  	}
  
  	ts->dev = dev;
  	spin_lock_init(&ts->lock);
  	setup_timer(&ts->timer, tsc_poll, (unsigned long)ts);
  	platform_set_drvdata(pdev, ts);
  
  	ts->tsc_irq = platform_get_irq(pdev, 0);
  	if (ts->tsc_irq < 0) {
  		dev_err(dev, "cannot determine device interrupt
  ");
  		error = -ENODEV;
  		goto error_res;
  	}
  
  	ts->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!ts->res) {
  		dev_err(dev, "cannot determine register area
  ");
  		error = -ENODEV;
  		goto error_res;
  	}
  
  	if (!request_mem_region(ts->res->start, resource_size(ts->res),
  				pdev->name)) {
  		dev_err(dev, "cannot claim register memory
  ");
  		ts->res = NULL;
  		error = -EINVAL;
  		goto error_res;
  	}
  
  	ts->regs = ioremap(ts->res->start, resource_size(ts->res));
  	if (!ts->regs) {
  		dev_err(dev, "cannot map register memory
  ");
  		error = -ENOMEM;
  		goto error_map;
  	}
  
  	ts->clk = clk_get(dev, NULL);
  	if (IS_ERR(ts->clk)) {
  		dev_err(dev, "cannot claim device clock
  ");
  		error = PTR_ERR(ts->clk);
  		goto error_clk;
  	}
  
  	error = request_threaded_irq(ts->tsc_irq, NULL, tsc_irq, IRQF_ONESHOT,
  				     dev_name(dev), ts);
  	if (error < 0) {
  		dev_err(ts->dev, "Could not allocate ts irq
  ");
  		goto error_irq;
  	}
  
  	ts->input_dev = input_allocate_device();
  	if (!ts->input_dev) {
  		dev_err(dev, "cannot allocate input device
  ");
  		error = -ENOMEM;
  		goto error_input;
  	}
  	input_set_drvdata(ts->input_dev, ts);
  
  	ts->input_dev->name       = pdev->name;
  	ts->input_dev->id.bustype = BUS_HOST;
  	ts->input_dev->dev.parent = &pdev->dev;
  	ts->input_dev->open	  = tsc_start;
  	ts->input_dev->close	  = tsc_stop;
  
  	clk_enable(ts->clk);
  	rev = tsc_read(ts, rev);
  	ts->input_dev->id.product = ((rev >>  8) & 0x07);
  	ts->input_dev->id.version = ((rev >> 16) & 0xfff);
  	clk_disable(ts->clk);
  
  	__set_bit(EV_KEY,    ts->input_dev->evbit);
  	__set_bit(EV_ABS,    ts->input_dev->evbit);
  	__set_bit(BTN_TOUCH, ts->input_dev->keybit);
  
  	input_set_abs_params(ts->input_dev, ABS_X, 0, 0xffff, 5, 0);
  	input_set_abs_params(ts->input_dev, ABS_Y, 0, 0xffff, 5, 0);
  	input_set_abs_params(ts->input_dev, ABS_PRESSURE, 0, 4095, 128, 0);
  
  	error = input_register_device(ts->input_dev);
  	if (error < 0) {
  		dev_err(dev, "failed input device registration
  ");
  		goto error_reg;
  	}
  
  	return 0;
  
  error_reg:
  	input_free_device(ts->input_dev);
  error_input:
  	free_irq(ts->tsc_irq, ts);
  error_irq:
  	clk_put(ts->clk);
  error_clk:
  	iounmap(ts->regs);
  error_map:
  	release_mem_region(ts->res->start, resource_size(ts->res));
  error_res:
  	kfree(ts);
  
  	return error;
  }
  
  static int tsc_remove(struct platform_device *pdev)
  {
  	struct tsc_data *ts = platform_get_drvdata(pdev);
  
  	input_unregister_device(ts->input_dev);
  	free_irq(ts->tsc_irq, ts);
  	clk_put(ts->clk);
  	iounmap(ts->regs);
  	release_mem_region(ts->res->start, resource_size(ts->res));
  	kfree(ts);
  
  	return 0;
  }
  
  static struct platform_driver tsc_driver = {
  	.probe		= tsc_probe,
  	.remove		= tsc_remove,
  	.driver.name	= "tnetv107x-ts",
  	.driver.owner	= THIS_MODULE,
  };
  module_platform_driver(tsc_driver);
  
  MODULE_AUTHOR("Cyril Chemparathy");
  MODULE_DESCRIPTION("TNETV107X Touchscreen Driver");
  MODULE_ALIAS("platform:tnetv107x-ts");
  MODULE_LICENSE("GPL");