/*
   * 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,...
  ",
  			 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
  ", 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
  ");
  
  	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
  ");
  		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
  ", 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
  ", 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");