/*
 * Driver for Motorola PCAP2 touchscreen as found in the EZX phone platform.
 *
 *  Copyright (C) 2006 Harald Welte <laforge@openezx.org>
 *  Copyright (C) 2009 Daniel Ribeiro <drwyrm@gmail.com>
 *
 *  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/fs.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/pm.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/mfd/ezx-pcap.h>

struct pcap_ts {
	struct pcap_chip *pcap;
	struct input_dev *input;
	struct delayed_work work;
	u16 x, y;
	u16 pressure;
	u8 read_state;
};

#define SAMPLE_DELAY	20 /* msecs */

#define X_AXIS_MIN	0
#define X_AXIS_MAX	1023
#define Y_AXIS_MAX	X_AXIS_MAX
#define Y_AXIS_MIN	X_AXIS_MIN
#define PRESSURE_MAX	X_AXIS_MAX
#define PRESSURE_MIN	X_AXIS_MIN

static void pcap_ts_read_xy(void *data, u16 res[2])
{
	struct pcap_ts *pcap_ts = data;

	switch (pcap_ts->read_state) {
	case PCAP_ADC_TS_M_PRESSURE:
		/* pressure reading is unreliable */
		if (res[0] > PRESSURE_MIN && res[0] < PRESSURE_MAX)
			pcap_ts->pressure = res[0];
		pcap_ts->read_state = PCAP_ADC_TS_M_XY;
		schedule_delayed_work(&pcap_ts->work, 0);
		break;
	case PCAP_ADC_TS_M_XY:
		pcap_ts->y = res[0];
		pcap_ts->x = res[1];
		if (pcap_ts->x <= X_AXIS_MIN || pcap_ts->x >= X_AXIS_MAX ||
		    pcap_ts->y <= Y_AXIS_MIN || pcap_ts->y >= Y_AXIS_MAX) {
			/* pen has been released */
			input_report_abs(pcap_ts->input, ABS_PRESSURE, 0);
			input_report_key(pcap_ts->input, BTN_TOUCH, 0);

			pcap_ts->read_state = PCAP_ADC_TS_M_STANDBY;
			schedule_delayed_work(&pcap_ts->work, 0);
		} else {
			/* pen is touching the screen */
			input_report_abs(pcap_ts->input, ABS_X, pcap_ts->x);
			input_report_abs(pcap_ts->input, ABS_Y, pcap_ts->y);
			input_report_key(pcap_ts->input, BTN_TOUCH, 1);
			input_report_abs(pcap_ts->input, ABS_PRESSURE,
						pcap_ts->pressure);

			/* switch back to pressure read mode */
			pcap_ts->read_state = PCAP_ADC_TS_M_PRESSURE;
			schedule_delayed_work(&pcap_ts->work,
					msecs_to_jiffies(SAMPLE_DELAY));
		}
		input_sync(pcap_ts->input);
		break;
	default:
		dev_warn(&pcap_ts->input->dev,
				"pcap_ts: Warning, unhandled read_state %d\n",
				pcap_ts->read_state);
		break;
	}
}

static void pcap_ts_work(struct work_struct *work)
{
	struct delayed_work *dw = to_delayed_work(work);
	struct pcap_ts *pcap_ts = container_of(dw, struct pcap_ts, work);
	u8 ch[2];

	pcap_set_ts_bits(pcap_ts->pcap,
			pcap_ts->read_state << PCAP_ADC_TS_M_SHIFT);

	if (pcap_ts->read_state == PCAP_ADC_TS_M_STANDBY)
		return;

	/* start adc conversion */
	ch[0] = PCAP_ADC_CH_TS_X1;
	ch[1] = PCAP_ADC_CH_TS_Y1;
	pcap_adc_async(pcap_ts->pcap, PCAP_ADC_BANK_1, 0, ch,
						pcap_ts_read_xy, pcap_ts);
}

static irqreturn_t pcap_ts_event_touch(int pirq, void *data)
{
	struct pcap_ts *pcap_ts = data;

	if (pcap_ts->read_state == PCAP_ADC_TS_M_STANDBY) {
		pcap_ts->read_state = PCAP_ADC_TS_M_PRESSURE;
		schedule_delayed_work(&pcap_ts->work, 0);
	}
	return IRQ_HANDLED;
}

static int pcap_ts_open(struct input_dev *dev)
{
	struct pcap_ts *pcap_ts = input_get_drvdata(dev);

	pcap_ts->read_state = PCAP_ADC_TS_M_STANDBY;
	schedule_delayed_work(&pcap_ts->work, 0);

	return 0;
}

static void pcap_ts_close(struct input_dev *dev)
{
	struct pcap_ts *pcap_ts = input_get_drvdata(dev);

	cancel_delayed_work_sync(&pcap_ts->work);

	pcap_ts->read_state = PCAP_ADC_TS_M_NONTS;
	pcap_set_ts_bits(pcap_ts->pcap,
				pcap_ts->read_state << PCAP_ADC_TS_M_SHIFT);
}

static int pcap_ts_probe(struct platform_device *pdev)
{
	struct input_dev *input_dev;
	struct pcap_ts *pcap_ts;
	int err = -ENOMEM;

	pcap_ts = kzalloc(sizeof(*pcap_ts), GFP_KERNEL);
	if (!pcap_ts)
		return err;

	pcap_ts->pcap = dev_get_drvdata(pdev->dev.parent);
	platform_set_drvdata(pdev, pcap_ts);

	input_dev = input_allocate_device();
	if (!input_dev)
		goto fail;

	INIT_DELAYED_WORK(&pcap_ts->work, pcap_ts_work);

	pcap_ts->read_state = PCAP_ADC_TS_M_NONTS;
	pcap_set_ts_bits(pcap_ts->pcap,
				pcap_ts->read_state << PCAP_ADC_TS_M_SHIFT);

	pcap_ts->input = input_dev;
	input_set_drvdata(input_dev, pcap_ts);

	input_dev->name = "pcap-touchscreen";
	input_dev->phys = "pcap_ts/input0";
	input_dev->id.bustype = BUS_HOST;
	input_dev->id.vendor = 0x0001;
	input_dev->id.product = 0x0002;
	input_dev->id.version = 0x0100;
	input_dev->dev.parent = &pdev->dev;
	input_dev->open = pcap_ts_open;
	input_dev->close = pcap_ts_close;

	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, X_AXIS_MIN, X_AXIS_MAX, 0, 0);
	input_set_abs_params(input_dev, ABS_Y, Y_AXIS_MIN, Y_AXIS_MAX, 0, 0);
	input_set_abs_params(input_dev, ABS_PRESSURE, PRESSURE_MIN,
			     PRESSURE_MAX, 0, 0);

	err = input_register_device(pcap_ts->input);
	if (err)
		goto fail_allocate;

	err = request_irq(pcap_to_irq(pcap_ts->pcap, PCAP_IRQ_TS),
			pcap_ts_event_touch, 0, "Touch Screen", pcap_ts);
	if (err)
		goto fail_register;

	return 0;

fail_register:
	input_unregister_device(input_dev);
	goto fail;
fail_allocate:
	input_free_device(input_dev);
fail:
	kfree(pcap_ts);

	return err;
}

static int pcap_ts_remove(struct platform_device *pdev)
{
	struct pcap_ts *pcap_ts = platform_get_drvdata(pdev);

	free_irq(pcap_to_irq(pcap_ts->pcap, PCAP_IRQ_TS), pcap_ts);
	cancel_delayed_work_sync(&pcap_ts->work);

	input_unregister_device(pcap_ts->input);

	kfree(pcap_ts);

	return 0;
}

#ifdef CONFIG_PM
static int pcap_ts_suspend(struct device *dev)
{
	struct pcap_ts *pcap_ts = dev_get_drvdata(dev);

	pcap_set_ts_bits(pcap_ts->pcap, PCAP_ADC_TS_REF_LOWPWR);
	return 0;
}

static int pcap_ts_resume(struct device *dev)
{
	struct pcap_ts *pcap_ts = dev_get_drvdata(dev);

	pcap_set_ts_bits(pcap_ts->pcap,
				pcap_ts->read_state << PCAP_ADC_TS_M_SHIFT);
	return 0;
}

static const struct dev_pm_ops pcap_ts_pm_ops = {
	.suspend	= pcap_ts_suspend,
	.resume		= pcap_ts_resume,
};
#define PCAP_TS_PM_OPS (&pcap_ts_pm_ops)
#else
#define PCAP_TS_PM_OPS NULL
#endif

static struct platform_driver pcap_ts_driver = {
	.probe		= pcap_ts_probe,
	.remove		= pcap_ts_remove,
	.driver		= {
		.name	= "pcap-ts",
		.pm	= PCAP_TS_PM_OPS,
	},
};
module_platform_driver(pcap_ts_driver);

MODULE_DESCRIPTION("Motorola PCAP2 touchscreen driver");
MODULE_AUTHOR("Daniel Ribeiro / Harald Welte");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:pcap_ts");