/*
 * Synaptics NavPoint (PXA27x SSP/SPI) driver.
 *
 * Copyright (C) 2012 Paul Parsons <lost.distance@yahoo.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/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/input.h>
#include <linux/input/navpoint.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/pxa2xx_ssp.h>
#include <linux/slab.h>

/*
 * Synaptics Modular Embedded Protocol: Module Packet Format.
 * Module header byte 2:0 = Length (# bytes that follow)
 * Module header byte 4:3 = Control
 * Module header byte 7:5 = Module Address
 */
#define HEADER_LENGTH(byte)	((byte) & 0x07)
#define HEADER_CONTROL(byte)	(((byte) >> 3) & 0x03)
#define HEADER_ADDRESS(byte)	((byte) >> 5)

struct navpoint {
	struct ssp_device	*ssp;
	struct input_dev	*input;
	struct device		*dev;
	int			gpio;
	int			index;
	u8			data[1 + HEADER_LENGTH(0xff)];
};

/*
 * Initialization values for SSCR0_x, SSCR1_x, SSSR_x.
 */
static const u32 sscr0 = 0
	| SSCR0_TUM		/* TIM = 1; No TUR interrupts */
	| SSCR0_RIM		/* RIM = 1; No ROR interrupts */
	| SSCR0_SSE		/* SSE = 1; SSP enabled */
	| SSCR0_Motorola	/* FRF = 0; Motorola SPI */
	| SSCR0_DataSize(16)	/* DSS = 15; Data size = 16-bit */
	;
static const u32 sscr1 = 0
	| SSCR1_SCFR		/* SCFR = 1; SSPSCLK only during transfers */
	| SSCR1_SCLKDIR		/* SCLKDIR = 1; Slave mode */
	| SSCR1_SFRMDIR		/* SFRMDIR = 1; Slave mode */
	| SSCR1_RWOT		/* RWOT = 1; Receive without transmit mode */
	| SSCR1_RxTresh(1)	/* RFT = 0; Receive FIFO threshold = 1 */
	| SSCR1_SPH		/* SPH = 1; SSPSCLK inactive 0.5 + 1 cycles */
	| SSCR1_RIE		/* RIE = 1; Receive FIFO interrupt enabled */
	;
static const u32 sssr = 0
	| SSSR_BCE		/* BCE = 1; Clear BCE */
	| SSSR_TUR		/* TUR = 1; Clear TUR */
	| SSSR_EOC		/* EOC = 1; Clear EOC */
	| SSSR_TINT		/* TINT = 1; Clear TINT */
	| SSSR_PINT		/* PINT = 1; Clear PINT */
	| SSSR_ROR		/* ROR = 1; Clear ROR */
	;

/*
 * MEP Query $22: Touchpad Coordinate Range Query is not supported by
 * the NavPoint module, so sampled values provide the default limits.
 */
#define NAVPOINT_X_MIN		1278
#define NAVPOINT_X_MAX		5340
#define NAVPOINT_Y_MIN		1572
#define NAVPOINT_Y_MAX		4396
#define NAVPOINT_PRESSURE_MIN	0
#define NAVPOINT_PRESSURE_MAX	255

static void navpoint_packet(struct navpoint *navpoint)
{
	int finger;
	int gesture;
	int x, y, z;

	switch (navpoint->data[0]) {
	case 0xff:	/* Garbage (packet?) between reset and Hello packet */
	case 0x00:	/* Module 0, NULL packet */
		break;

	case 0x0e:	/* Module 0, Absolute packet */
		finger = (navpoint->data[1] & 0x01);
		gesture = (navpoint->data[1] & 0x02);
		x = ((navpoint->data[2] & 0x1f) << 8) | navpoint->data[3];
		y = ((navpoint->data[4] & 0x1f) << 8) | navpoint->data[5];
		z = navpoint->data[6];
		input_report_key(navpoint->input, BTN_TOUCH, finger);
		input_report_abs(navpoint->input, ABS_X, x);
		input_report_abs(navpoint->input, ABS_Y, y);
		input_report_abs(navpoint->input, ABS_PRESSURE, z);
		input_report_key(navpoint->input, BTN_TOOL_FINGER, finger);
		input_report_key(navpoint->input, BTN_LEFT, gesture);
		input_sync(navpoint->input);
		break;

	case 0x19:	/* Module 0, Hello packet */
		if ((navpoint->data[1] & 0xf0) == 0x10)
			break;
		/* FALLTHROUGH */
	default:
		dev_warn(navpoint->dev,
			 "spurious packet: data=0x%02x,0x%02x,...\n",
			 navpoint->data[0], navpoint->data[1]);
		break;
	}
}

static irqreturn_t navpoint_irq(int irq, void *dev_id)
{
	struct navpoint *navpoint = dev_id;
	struct ssp_device *ssp = navpoint->ssp;
	irqreturn_t ret = IRQ_NONE;
	u32 status;

	status = pxa_ssp_read_reg(ssp, SSSR);
	if (status & sssr) {
		dev_warn(navpoint->dev,
			 "unexpected interrupt: status=0x%08x\n", status);
		pxa_ssp_write_reg(ssp, SSSR, (status & sssr));
		ret = IRQ_HANDLED;
	}

	while (status & SSSR_RNE) {
		u32 data;

		data = pxa_ssp_read_reg(ssp, SSDR);
		navpoint->data[navpoint->index + 0] = (data >> 8);
		navpoint->data[navpoint->index + 1] = data;
		navpoint->index += 2;
		if (HEADER_LENGTH(navpoint->data[0]) < navpoint->index) {
			navpoint_packet(navpoint);
			navpoint->index = 0;
		}
		status = pxa_ssp_read_reg(ssp, SSSR);
		ret = IRQ_HANDLED;
	}

	return ret;
}

static void navpoint_up(struct navpoint *navpoint)
{
	struct ssp_device *ssp = navpoint->ssp;
	int timeout;

	clk_prepare_enable(ssp->clk);

	pxa_ssp_write_reg(ssp, SSCR1, sscr1);
	pxa_ssp_write_reg(ssp, SSSR, sssr);
	pxa_ssp_write_reg(ssp, SSTO, 0);
	pxa_ssp_write_reg(ssp, SSCR0, sscr0);	/* SSCR0_SSE written last */

	/* Wait until SSP port is ready for slave clock operations */
	for (timeout = 100; timeout != 0; --timeout) {
		if (!(pxa_ssp_read_reg(ssp, SSSR) & SSSR_CSS))
			break;
		msleep(1);
	}

	if (timeout == 0)
		dev_err(navpoint->dev,
			"timeout waiting for SSSR[CSS] to clear\n");

	if (gpio_is_valid(navpoint->gpio))
		gpio_set_value(navpoint->gpio, 1);
}

static void navpoint_down(struct navpoint *navpoint)
{
	struct ssp_device *ssp = navpoint->ssp;

	if (gpio_is_valid(navpoint->gpio))
		gpio_set_value(navpoint->gpio, 0);

	pxa_ssp_write_reg(ssp, SSCR0, 0);

	clk_disable_unprepare(ssp->clk);
}

static int navpoint_open(struct input_dev *input)
{
	struct navpoint *navpoint = input_get_drvdata(input);

	navpoint_up(navpoint);

	return 0;
}

static void navpoint_close(struct input_dev *input)
{
	struct navpoint *navpoint = input_get_drvdata(input);

	navpoint_down(navpoint);
}

static int navpoint_probe(struct platform_device *pdev)
{
	const struct navpoint_platform_data *pdata =
					dev_get_platdata(&pdev->dev);
	struct ssp_device *ssp;
	struct input_dev *input;
	struct navpoint *navpoint;
	int error;

	if (!pdata) {
		dev_err(&pdev->dev, "no platform data\n");
		return -EINVAL;
	}

	if (gpio_is_valid(pdata->gpio)) {
		error = gpio_request_one(pdata->gpio, GPIOF_OUT_INIT_LOW,
					 "SYNAPTICS_ON");
		if (error)
			return error;
	}

	ssp = pxa_ssp_request(pdata->port, pdev->name);
	if (!ssp) {
		error = -ENODEV;
		goto err_free_gpio;
	}

	/* HaRET does not disable devices before jumping into Linux */
	if (pxa_ssp_read_reg(ssp, SSCR0) & SSCR0_SSE) {
		pxa_ssp_write_reg(ssp, SSCR0, 0);
		dev_warn(&pdev->dev, "ssp%d already enabled\n", pdata->port);
	}

	navpoint = kzalloc(sizeof(*navpoint), GFP_KERNEL);
	input = input_allocate_device();
	if (!navpoint || !input) {
		error = -ENOMEM;
		goto err_free_mem;
	}

	navpoint->ssp = ssp;
	navpoint->input = input;
	navpoint->dev = &pdev->dev;
	navpoint->gpio = pdata->gpio;

	input->name = pdev->name;
	input->dev.parent = &pdev->dev;

	__set_bit(EV_KEY, input->evbit);
	__set_bit(EV_ABS, input->evbit);
	__set_bit(BTN_LEFT, input->keybit);
	__set_bit(BTN_TOUCH, input->keybit);
	__set_bit(BTN_TOOL_FINGER, input->keybit);

	input_set_abs_params(input, ABS_X,
			     NAVPOINT_X_MIN, NAVPOINT_X_MAX, 0, 0);
	input_set_abs_params(input, ABS_Y,
			     NAVPOINT_Y_MIN, NAVPOINT_Y_MAX, 0, 0);
	input_set_abs_params(input, ABS_PRESSURE,
			     NAVPOINT_PRESSURE_MIN, NAVPOINT_PRESSURE_MAX,
			     0, 0);

	input->open = navpoint_open;
	input->close = navpoint_close;

	input_set_drvdata(input, navpoint);

	error = request_irq(ssp->irq, navpoint_irq, 0, pdev->name, navpoint);
	if (error)
		goto err_free_mem;

	error = input_register_device(input);
	if (error)
		goto err_free_irq;

	platform_set_drvdata(pdev, navpoint);
	dev_dbg(&pdev->dev, "ssp%d, irq %d\n", pdata->port, ssp->irq);

	return 0;

err_free_irq:
	free_irq(ssp->irq, navpoint);
err_free_mem:
	input_free_device(input);
	kfree(navpoint);
	pxa_ssp_free(ssp);
err_free_gpio:
	if (gpio_is_valid(pdata->gpio))
		gpio_free(pdata->gpio);

	return error;
}

static int navpoint_remove(struct platform_device *pdev)
{
	const struct navpoint_platform_data *pdata =
					dev_get_platdata(&pdev->dev);
	struct navpoint *navpoint = platform_get_drvdata(pdev);
	struct ssp_device *ssp = navpoint->ssp;

	free_irq(ssp->irq, navpoint);

	input_unregister_device(navpoint->input);
	kfree(navpoint);

	pxa_ssp_free(ssp);

	if (gpio_is_valid(pdata->gpio))
		gpio_free(pdata->gpio);

	return 0;
}

static int __maybe_unused navpoint_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct navpoint *navpoint = platform_get_drvdata(pdev);
	struct input_dev *input = navpoint->input;

	mutex_lock(&input->mutex);
	if (input->users)
		navpoint_down(navpoint);
	mutex_unlock(&input->mutex);

	return 0;
}

static int __maybe_unused navpoint_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct navpoint *navpoint = platform_get_drvdata(pdev);
	struct input_dev *input = navpoint->input;

	mutex_lock(&input->mutex);
	if (input->users)
		navpoint_up(navpoint);
	mutex_unlock(&input->mutex);

	return 0;
}

static SIMPLE_DEV_PM_OPS(navpoint_pm_ops, navpoint_suspend, navpoint_resume);

static struct platform_driver navpoint_driver = {
	.probe		= navpoint_probe,
	.remove		= navpoint_remove,
	.driver = {
		.name	= "navpoint",
		.pm	= &navpoint_pm_ops,
	},
};

module_platform_driver(navpoint_driver);

MODULE_AUTHOR("Paul Parsons <lost.distance@yahoo.com>");
MODULE_DESCRIPTION("Synaptics NavPoint (PXA27x SSP/SPI) driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:navpoint");