/*

   * Intel MID Resistive Touch Screen Driver

   *
   * Copyright (C) 2008 Intel Corp
   *
   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   *
   * 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 of the License.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License along

   * with this program; if not, write to the Free Software Foundation, Inc.,

   * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
   *
   * Questions/Comments/Bug fixes to Sreedhara (sreedhara.ds@intel.com)

   *			    Ramesh Agarwal (ramesh.agarwal@intel.com)

   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   *
   * TODO:

   *	review conversion of r/m/w sequences

   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/input.h>
  #include <linux/interrupt.h>
  #include <linux/err.h>
  #include <linux/param.h>

  #include <linux/slab.h>
  #include <linux/platform_device.h>

  #include <linux/irq.h>
  #include <linux/delay.h>

  #include <asm/intel_scu_ipc.h>

  /* PMIC Interrupt registers */

  #define PMIC_REG_ID1		0x00 /* PMIC ID1 register */

  
  /* PMIC Interrupt registers */

  #define PMIC_REG_INT		0x04 /* PMIC interrupt register */
  #define PMIC_REG_MINT		0x05 /* PMIC interrupt mask register */

  
  /* ADC Interrupt registers */

  #define PMIC_REG_ADCINT		0x5F /* ADC interrupt register */
  #define PMIC_REG_MADCINT	0x60 /* ADC interrupt mask register */

  
  /* ADC Control registers */

  #define PMIC_REG_ADCCNTL1	0x61 /* ADC control register */

  
  /* ADC Channel Selection registers */

  #define PMICADDR0		0xA4
  #define END_OF_CHANNEL		0x1F

  
  /* ADC Result register */

  #define PMIC_REG_ADCSNS0H	0x64

  
  /* ADC channels for touch screen */

  #define MRST_TS_CHAN10		0xA /* Touch screen X+ connection */
  #define MRST_TS_CHAN11		0xB /* Touch screen X- connection */
  #define MRST_TS_CHAN12		0xC /* Touch screen Y+ connection */
  #define MRST_TS_CHAN13		0xD /* Touch screen Y- connection */

  
  /* Touch screen channel BIAS constants */

  #define MRST_XBIAS		0x20
  #define MRST_YBIAS		0x40
  #define MRST_ZBIAS		0x80

  
  /* Touch screen coordinates */

  #define MRST_X_MIN		10
  #define MRST_X_MAX		1024
  #define MRST_X_FUZZ		5
  #define MRST_Y_MIN		10
  #define MRST_Y_MAX		1024
  #define MRST_Y_FUZZ		5
  #define MRST_PRESSURE_MIN	0
  #define MRST_PRESSURE_NOMINAL	50
  #define MRST_PRESSURE_MAX	100
  
  #define WAIT_ADC_COMPLETION	10 /* msec */

  
  /* PMIC ADC round robin delays */

  #define ADC_LOOP_DELAY0		0x0 /* Continuous loop */
  #define ADC_LOOP_DELAY1		0x1 /* 4.5  ms approximate */

  
  /* PMIC Vendor Identifiers */

  #define PMIC_VENDOR_FS		0 /* PMIC vendor FreeScale */
  #define PMIC_VENDOR_MAXIM	1 /* PMIC vendor MAXIM */
  #define PMIC_VENDOR_NEC		2 /* PMIC vendor NEC */
  #define MRSTOUCH_MAX_CHANNELS	32 /* Maximum ADC channels */

  
  /* Touch screen device structure */
  struct mrstouch_dev {

  	struct device *dev; /* device associated with touch screen */

  	struct input_dev *input;
  	char phys[32];
  	u16 asr;		/* Address selection register */
  	int irq;
  	unsigned int vendor;	/* PMIC vendor */
  	unsigned int rev;	/* PMIC revision */
  
  	int (*read_prepare)(struct mrstouch_dev *tsdev);
  	int (*read)(struct mrstouch_dev *tsdev, u16 *x, u16 *y, u16 *z);
  	int (*read_finish)(struct mrstouch_dev *tsdev);
  };

  
  /*************************** NEC and Maxim Interface ************************/
  
  static int mrstouch_nec_adc_read_prepare(struct mrstouch_dev *tsdev)

  {

  	return intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0, 0x20);

  }
  
  /*

   * Enables PENDET interrupt.

   */

  static int mrstouch_nec_adc_read_finish(struct mrstouch_dev *tsdev)

  {

  	int err;

  	err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x20, 0x20);
  	if (!err)
  		err = intel_scu_ipc_update_register(PMIC_REG_ADCCNTL1, 0, 0x05);

  	return err;

  }

  /*
   * Reads PMIC ADC touch screen result
   * Reads ADC storage registers for higher 7 and lower 3 bits and
   * converts the two readings into a single value and turns off gain bit

   */
  static int mrstouch_ts_chan_read(u16 offset, u16 chan, u16 *vp, u16 *vm)
  {
  	int err;
  	u16 result;
  	u32 res;
  
  	result = PMIC_REG_ADCSNS0H + offset;
  
  	if (chan == MRST_TS_CHAN12)
  		result += 4;
  
  	err = intel_scu_ipc_ioread32(result, &res);
  	if (err)
  		return err;
  
  	/* Mash the bits up */
  
  	*vp = (res & 0xFF) << 3;	/* Highest 7 bits */
  	*vp |= (res >> 8) & 0x07;	/* Lower 3 bits */
  	*vp &= 0x3FF;
  
  	res >>= 16;
  
  	*vm = (res & 0xFF) << 3;	/* Highest 7 bits */
  	*vm |= (res >> 8) & 0x07;	/* Lower 3 bits */
  	*vm &= 0x3FF;
  
  	return 0;
  }

  /*
   * Enables X, Y and Z bias values
   * Enables YPYM for X channels and XPXM for Y channels

   */

  static int mrstouch_ts_bias_set(uint offset, uint bias)

  {
  	int count;

  	u16 chan, start;
  	u16 reg[4];
  	u8 data[4];

  
  	chan = PMICADDR0 + offset;

  	start = MRST_TS_CHAN10;

  	for (count = 0; count <= 3; count++) {
  		reg[count] = chan++;

  		data[count] = bias | (start + count);

  	}

  	return intel_scu_ipc_writev(reg, data, 4);

  }

  /* To read touch screen channel values */
  static int mrstouch_nec_adc_read(struct mrstouch_dev *tsdev,
  				 u16 *x, u16 *y, u16 *z)

  {
  	int err;

  	u16 xm, ym, zm;

  	/* configure Y bias for X channels */
  	err = mrstouch_ts_bias_set(tsdev->asr, MRST_YBIAS);
  	if (err)
  		goto ipc_error;

  	msleep(WAIT_ADC_COMPLETION);

  	/* read x+ and x- channels */
  	err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN10, x, &xm);

  	if (err)
  		goto ipc_error;

  	/* configure x bias for y channels */
  	err = mrstouch_ts_bias_set(tsdev->asr, MRST_XBIAS);
  	if (err)
  		goto ipc_error;

  	msleep(WAIT_ADC_COMPLETION);

  	/* read y+ and y- channels */
  	err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN12, y, &ym);
  	if (err)
  		goto ipc_error;

  	/* configure z bias for x and y channels */
  	err = mrstouch_ts_bias_set(tsdev->asr, MRST_ZBIAS);

  	if (err)
  		goto ipc_error;

  	msleep(WAIT_ADC_COMPLETION);
  
  	/* read z+ and z- channels */
  	err = mrstouch_ts_chan_read(tsdev->asr, MRST_TS_CHAN10, z, &zm);
  	if (err)
  		goto ipc_error;

  	return 0;
  
  ipc_error:

  	dev_err(tsdev->dev, "ipc error during adc read
  ");

  	return err;
  }

  
  /*************************** Freescale Interface ************************/
  
  static int mrstouch_fs_adc_read_prepare(struct mrstouch_dev *tsdev)

  {
  	int err, count;
  	u16 chan;

  	u16 reg[5];
  	u8 data[5];

  	/* Stop the ADC */
  	err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x00, 0x02);
  	if (err)
  		goto ipc_error;

  	chan = PMICADDR0 + tsdev->asr;
  
  	/* Set X BIAS */
  	for (count = 0; count <= 3; count++) {
  		reg[count] = chan++;
  		data[count] = 0x2A;
  	}
  	reg[count] =  chan++; /* Dummy */
  	data[count] = 0;
  
  	err = intel_scu_ipc_writev(reg, data, 5);
  	if (err)
  		goto ipc_error;
  
  	msleep(WAIT_ADC_COMPLETION);
  
  	/* Set Y BIAS */
  	for (count = 0; count <= 3; count++) {
  		reg[count] = chan++;
  		data[count] = 0x4A;
  	}
  	reg[count] = chan++; /* Dummy */
  	data[count] = 0;
  
  	err = intel_scu_ipc_writev(reg, data, 5);
  	if (err)
  		goto ipc_error;
  
  	msleep(WAIT_ADC_COMPLETION);
  
  	/* Set Z BIAS */
  	err = intel_scu_ipc_iowrite32(chan + 2, 0x8A8A8A8A);
  	if (err)
  		goto ipc_error;
  
  	msleep(WAIT_ADC_COMPLETION);

  	return 0;
  
  ipc_error:

  	dev_err(tsdev->dev, "ipc error during %s
  ", __func__);

  	return err;
  }
  
  static int mrstouch_fs_adc_read(struct mrstouch_dev *tsdev,
  				u16 *x, u16 *y, u16 *z)
  {
  	int err;
  	u16 result;
  	u16 reg[4];
  	u8 data[4];
  
  	result = PMIC_REG_ADCSNS0H + tsdev->asr;
  
  	reg[0] = result + 4;
  	reg[1] = result + 5;
  	reg[2] = result + 16;
  	reg[3] = result + 17;
  
  	err = intel_scu_ipc_readv(reg, data, 4);
  	if (err)
  		goto ipc_error;
  
  	*x = data[0] << 3; /* Higher 7 bits */
  	*x |= data[1] & 0x7; /* Lower 3 bits */
  	*x &= 0x3FF;
  
  	*y = data[2] << 3; /* Higher 7 bits */
  	*y |= data[3] & 0x7; /* Lower 3 bits */
  	*y &= 0x3FF;
  
  	/* Read Z value */
  	reg[0] = result + 28;
  	reg[1] = result + 29;
  
  	err = intel_scu_ipc_readv(reg, data, 4);
  	if (err)
  		goto ipc_error;
  
  	*z = data[0] << 3; /* Higher 7 bits */
  	*z |= data[1] & 0x7; /* Lower 3 bits */
  	*z &= 0x3FF;
  
  	return 0;
  
  ipc_error:

  	dev_err(tsdev->dev, "ipc error during %s
  ", __func__);

  	return err;
  }
  
  static int mrstouch_fs_adc_read_finish(struct mrstouch_dev *tsdev)
  {
  	int err, count;
  	u16 chan;
  	u16 reg[5];
  	u8 data[5];

  
  	/* Clear all TS channels */
  	chan = PMICADDR0 + tsdev->asr;
  	for (count = 0; count <= 4; count++) {
  		reg[count] = chan++;
  		data[count] = 0;
  	}
  	err = intel_scu_ipc_writev(reg, data, 5);
  	if (err)
  		goto ipc_error;
  
  	for (count = 0; count <= 4; count++) {
  		reg[count] = chan++;
  		data[count] = 0;
  	}
  	err = intel_scu_ipc_writev(reg, data, 5);
  	if (err)
  		goto ipc_error;
  
  	err = intel_scu_ipc_iowrite32(chan + 2, 0x00000000);
  	if (err)
  		goto ipc_error;

  	/* Start ADC */
  	err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, 0x02, 0x02);
  	if (err)
  		goto ipc_error;

  	return 0;
  
  ipc_error:

  	dev_err(tsdev->dev, "ipc error during %s
  ", __func__);

  	return err;
  }

  static void mrstouch_report_event(struct input_dev *input,
  			unsigned int x, unsigned int y, unsigned int z)

  {

  	if (z > MRST_PRESSURE_NOMINAL) {
  		/* Pen touched, report button touch and coordinates */
  		input_report_key(input, BTN_TOUCH, 1);
  		input_report_abs(input, ABS_X, x);
  		input_report_abs(input, ABS_Y, y);
  	} else {
  		input_report_key(input, BTN_TOUCH, 0);

  	}

  
  	input_report_abs(input, ABS_PRESSURE, z);
  	input_sync(input);

  }

  /* PENDET interrupt handler */
  static irqreturn_t mrstouch_pendet_irq(int irq, void *dev_id)

  {

  	struct mrstouch_dev *tsdev = dev_id;
  	u16 x, y, z;

  	/*
  	 * Should we lower thread priority? Probably not, since we are
  	 * not spinning but sleeping...
  	 */

  	if (tsdev->read_prepare(tsdev))
  		goto out;

  	do {
  		if (tsdev->read(tsdev, &x, &y, &z))
  			break;

  		mrstouch_report_event(tsdev->input, x, y, z);
  	} while (z > MRST_PRESSURE_NOMINAL);

  	tsdev->read_finish(tsdev);

  out:
  	return IRQ_HANDLED;
  }

  /* Utility to read PMIC ID */
  static int __devinit mrstouch_read_pmic_id(uint *vendor, uint *rev)
  {
  	int err;
  	u8 r;

  	err = intel_scu_ipc_ioread8(PMIC_REG_ID1, &r);

  	if (err)

  		return err;

  	*vendor = r & 0x7;
  	*rev = (r >> 3) & 0x7;

  	return 0;

  }

  /*
   * Parse ADC channels to find end of the channel configured by other ADC user
   * NEC and MAXIM requires 4 channels and FreeScale needs 18 channels
   */
  static int __devinit mrstouch_chan_parse(struct mrstouch_dev *tsdev)

  {

  	int found = 0;
  	int err, i;

  	u8 r8;

  	for (i = 0; i < MRSTOUCH_MAX_CHANNELS; i++) {

  		err = intel_scu_ipc_ioread8(PMICADDR0 + i, &r8);

  		if (err)
  			return err;

  		if (r8 == END_OF_CHANNEL) {
  			found = i;
  			break;

  		}
  	}

  	if (tsdev->vendor == PMIC_VENDOR_FS) {

  		if (found > MRSTOUCH_MAX_CHANNELS - 18)

  			return -ENOSPC;
  	} else {

  		if (found > MRSTOUCH_MAX_CHANNELS - 4)

  			return -ENOSPC;

  	}

  	return found;

  }

  
  /*
   * Writes touch screen channels to ADC address selection registers
   */
  static int __devinit mrstouch_ts_chan_set(uint offset)

  {

  	u16 chan;

  
  	int ret, count;

  	chan = PMICADDR0 + offset;
  	for (count = 0; count <= 3; count++) {

  		ret = intel_scu_ipc_iowrite8(chan++, MRST_TS_CHAN10 + count);
  		if (ret)
  			return ret;

  	}

  	return intel_scu_ipc_iowrite8(chan++, END_OF_CHANNEL);

  }

  /* Initialize ADC */
  static int __devinit mrstouch_adc_init(struct mrstouch_dev *tsdev)

  {

  	int err, start;
  	u8 ra, rm;

  	err = mrstouch_read_pmic_id(&tsdev->vendor, &tsdev->rev);
  	if (err) {

  		dev_err(tsdev->dev, "Unable to read PMIC id
  ");

  		return err;

  	}

  	switch (tsdev->vendor) {
  	case PMIC_VENDOR_NEC:
  	case PMIC_VENDOR_MAXIM:
  		tsdev->read_prepare = mrstouch_nec_adc_read_prepare;
  		tsdev->read = mrstouch_nec_adc_read;
  		tsdev->read_finish = mrstouch_nec_adc_read_finish;
  		break;
  
  	case PMIC_VENDOR_FS:
  		tsdev->read_prepare = mrstouch_fs_adc_read_prepare;
  		tsdev->read = mrstouch_fs_adc_read;
  		tsdev->read_finish = mrstouch_fs_adc_read_finish;
  		break;
  
  	default:

  		dev_err(tsdev->dev,

  			"Unsupported touchscreen: %d
  ", tsdev->vendor);
  		return -ENXIO;
  	}

  	start = mrstouch_chan_parse(tsdev);
  	if (start < 0) {

  		dev_err(tsdev->dev, "Unable to parse channels
  ");

  		return start;
  	}

  	tsdev->asr = start;

  	/*
  	 * ADC power on, start, enable PENDET and set loop delay
  	 * ADC loop delay is set to 4.5 ms approximately
  	 * Loop delay more than this results in jitter in adc readings

  	 * Setting loop delay to 0 (continuous loop) in MAXIM stops PENDET

  	 * interrupt generation sometimes.
  	 */

  	if (tsdev->vendor == PMIC_VENDOR_FS) {
  		ra = 0xE0 | ADC_LOOP_DELAY0;
  		rm = 0x5;
  	} else {
  		/* NEC and MAXIm not consistent with loop delay 0 */
  		ra = 0xE0 | ADC_LOOP_DELAY1;
  		rm = 0x0;
  
  		/* configure touch screen channels */
  		err = mrstouch_ts_chan_set(tsdev->asr);
  		if (err)
  			return err;

  	}

  	err = intel_scu_ipc_update_register(PMIC_REG_ADCCNTL1, ra, 0xE7);
  	if (err)
  		return err;
  
  	err = intel_scu_ipc_update_register(PMIC_REG_MADCINT, rm, 0x03);
  	if (err)
  		return err;
  
  	return 0;

  }

  /* Probe function for touch screen driver */

  static int __devinit mrstouch_probe(struct platform_device *pdev)

  {

  	struct mrstouch_dev *tsdev;

  	struct input_dev *input;
  	int err;

  	int irq;

  	irq = platform_get_irq(pdev, 0);
  	if (irq < 0) {
  		dev_err(&pdev->dev, "no interrupt assigned
  ");

  		return -EINVAL;
  	}
  
  	tsdev = kzalloc(sizeof(struct mrstouch_dev), GFP_KERNEL);

  	input = input_allocate_device();
  	if (!tsdev || !input) {

  		dev_err(&pdev->dev, "unable to allocate memory
  ");

  		err = -ENOMEM;
  		goto err_free_mem;

  	}

  	tsdev->dev = &pdev->dev;

  	tsdev->input = input;

  	tsdev->irq = irq;

  
  	snprintf(tsdev->phys, sizeof(tsdev->phys),

  		 "%s/input0", dev_name(tsdev->dev));

  
  	err = mrstouch_adc_init(tsdev);
  	if (err) {

  		dev_err(&pdev->dev, "ADC initialization failed
  ");

  		goto err_free_mem;

  	}

  	input->name = "mrst_touchscreen";
  	input->phys = tsdev->phys;

  	input->dev.parent = tsdev->dev;

  	input->id.vendor = tsdev->vendor;
  	input->id.version = tsdev->rev;

  	input->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
  	input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

  	input_set_abs_params(tsdev->input, ABS_X,
  			     MRST_X_MIN, MRST_X_MAX, MRST_X_FUZZ, 0);
  	input_set_abs_params(tsdev->input, ABS_Y,
  			     MRST_Y_MIN, MRST_Y_MAX, MRST_Y_FUZZ, 0);
  	input_set_abs_params(tsdev->input, ABS_PRESSURE,
  			     MRST_PRESSURE_MIN, MRST_PRESSURE_MAX, 0, 0);
  
  	err = request_threaded_irq(tsdev->irq, NULL, mrstouch_pendet_irq,
  				   0, "mrstouch", tsdev);

  	if (err) {

  		dev_err(tsdev->dev, "unable to allocate irq
  ");

  		goto err_free_mem;

  	}

  	err = input_register_device(tsdev->input);
  	if (err) {

  		dev_err(tsdev->dev, "unable to register input device
  ");

  		goto err_free_irq;

  	}

  	platform_set_drvdata(pdev, tsdev);

  	return 0;

  
  err_free_irq:
  	free_irq(tsdev->irq, tsdev);
  err_free_mem:
  	input_free_device(input);

  	kfree(tsdev);
  	return err;
  }

  static int __devexit mrstouch_remove(struct platform_device *pdev)

  {

  	struct mrstouch_dev *tsdev = platform_get_drvdata(pdev);

  
  	free_irq(tsdev->irq, tsdev);
  	input_unregister_device(tsdev->input);
  	kfree(tsdev);

  	platform_set_drvdata(pdev, NULL);

  	return 0;
  }

  static struct platform_driver mrstouch_driver = {

  	.driver = {

  		.name	= "pmic_touch",
  		.owner	= THIS_MODULE,

  	},

  	.probe		= mrstouch_probe,
  	.remove		= __devexit_p(mrstouch_remove),

  };

  static int __init mrstouch_init(void)

  {

  	return platform_driver_register(&mrstouch_driver);

  }

  module_init(mrstouch_init);

  static void __exit mrstouch_exit(void)

  {

  	platform_driver_unregister(&mrstouch_driver);

  }

  module_exit(mrstouch_exit);

  
  MODULE_AUTHOR("Sreedhara Murthy. D.S, sreedhara.ds@intel.com");
  MODULE_DESCRIPTION("Intel Moorestown Resistive Touch Screen Driver");
  MODULE_LICENSE("GPL");