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/*
 * Input driver for slidebars on some Lenovo IdeaPad laptops
 *
 * Copyright (C) 2013 Andrey Moiseev <o2g.org.ru@gmail.com>
 *
 * Reverse-engineered from Lenovo SlideNav software (SBarHook.dll).
 *
 * 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; either version 2 of the License, or (at your option)
 * any later version.
 *
 * Trademarks are the property of their respective owners.
 */

/*
 * Currently tested and works on:
 *	Lenovo IdeaPad Y550
 *	Lenovo IdeaPad Y550P
 *
 * Other models can be added easily. To test,
 * load with 'force' parameter set 'true'.
 *
 * LEDs blinking and input mode are managed via sysfs,
 * (hex, unsigned byte value):
 * /sys/devices/platform/ideapad_slidebar/slidebar_mode
 *
 * The value is in byte range, however, I only figured out
 * how bits 0b10011001 work. Some other bits, probably,
 * are meaningfull too.
 *
 * Possible states:
 *
 * STD_INT, ONMOV_INT, OFF_INT, LAST_POLL, OFF_POLL
 *
 * Meaning:
 *           released      touched
 * STD       'heartbeat'   lights follow the finger
 * ONMOV     no lights     lights follow the finger
 * LAST      at last pos   lights follow the finger
 * OFF       no lights     no lights
 *
 * INT       all input events are generated, interrupts are used
 * POLL      no input events by default, to get them,
 *	     send 0b10000000 (read below)
 *
 * Commands: write
 *
 * All      |  0b01001 -> STD_INT
 * possible |  0b10001 -> ONMOV_INT
 * states   |  0b01000 -> OFF_INT
 *
 *                      |  0b0 -> LAST_POLL
 * STD_INT or ONMOV_INT |
 *                      |  0b1 -> STD_INT
 *
 *                      |  0b0 -> OFF_POLL
 * OFF_INT or OFF_POLL  |
 *                      |  0b1 -> OFF_INT
 *
 * Any state |   0b10000000 ->  if the slidebar has updated data,
 *				produce one input event (last position),
 *				switch to respective POLL mode
 *				(like 0x0), if not in POLL mode yet.
 *
 * Get current state: read
 *
 * masked by 0x11 read value means:
 *
 * 0x00   LAST
 * 0x01   STD
 * 0x10   OFF
 * 0x11   ONMOV
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/dmi.h>
#include <linux/spinlock.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/i8042.h>
#include <linux/serio.h>

#define IDEAPAD_BASE	0xff29

static bool force;
module_param(force, bool, 0);
MODULE_PARM_DESC(force, "Force driver load, ignore DMI data");

static DEFINE_SPINLOCK(io_lock);

static struct input_dev *slidebar_input_dev;
static struct platform_device *slidebar_platform_dev;

static u8 slidebar_pos_get(void)
{
	u8 res;
	unsigned long flags;

	spin_lock_irqsave(&io_lock, flags);
	outb(0xf4, 0xff29);
	outb(0xbf, 0xff2a);
	res = inb(0xff2b);
	spin_unlock_irqrestore(&io_lock, flags);

	return res;
}

static u8 slidebar_mode_get(void)
{
	u8 res;
	unsigned long flags;

	spin_lock_irqsave(&io_lock, flags);
	outb(0xf7, 0xff29);
	outb(0x8b, 0xff2a);
	res = inb(0xff2b);
	spin_unlock_irqrestore(&io_lock, flags);

	return res;
}

static void slidebar_mode_set(u8 mode)
{
	unsigned long flags;

	spin_lock_irqsave(&io_lock, flags);
	outb(0xf7, 0xff29);
	outb(0x8b, 0xff2a);
	outb(mode, 0xff2b);
	spin_unlock_irqrestore(&io_lock, flags);
}

static bool slidebar_i8042_filter(unsigned char data, unsigned char str,
				  struct serio *port)
{
	static bool extended = false;

	/* We are only interested in data coming form KBC port */
	if (str & I8042_STR_AUXDATA)
		return false;

	/* Scancodes: e03b on move, e0bb on release. */
	if (data == 0xe0) {
		extended = true;
		return true;
	}

	if (!extended)
		return false;

	extended = false;

	if (likely((data & 0x7f) != 0x3b)) {
		serio_interrupt(port, 0xe0, 0);
		return false;
	}

	if (data & 0x80) {
		input_report_key(slidebar_input_dev, BTN_TOUCH, 0);
	} else {
		input_report_key(slidebar_input_dev, BTN_TOUCH, 1);
		input_report_abs(slidebar_input_dev, ABS_X, slidebar_pos_get());
	}
	input_sync(slidebar_input_dev);

	return true;
}

static ssize_t show_slidebar_mode(struct device *dev,
				  struct device_attribute *attr,
				  char *buf)
{
	return sprintf(buf, "%x\n", slidebar_mode_get());
}

static ssize_t store_slidebar_mode(struct device *dev,
				   struct device_attribute *attr,
				   const char *buf, size_t count)
{
	u8 mode;
	int error;

	error = kstrtou8(buf, 0, &mode);
	if (error)
		return error;

	slidebar_mode_set(mode);

	return count;
}

static DEVICE_ATTR(slidebar_mode, S_IWUSR | S_IRUGO,
		   show_slidebar_mode, store_slidebar_mode);

static struct attribute *ideapad_attrs[] = {
	&dev_attr_slidebar_mode.attr,
	NULL
};

static struct attribute_group ideapad_attr_group = {
	.attrs = ideapad_attrs
};

static const struct attribute_group *ideapad_attr_groups[] = {
	&ideapad_attr_group,
	NULL
};

static int __init ideapad_probe(struct platform_device* pdev)
{
	int err;

	if (!request_region(IDEAPAD_BASE, 3, "ideapad_slidebar")) {
		dev_err(&pdev->dev, "IO ports are busy\n");
		return -EBUSY;
	}

	slidebar_input_dev = input_allocate_device();
	if (!slidebar_input_dev) {
		dev_err(&pdev->dev, "Failed to allocate input device\n");
		err = -ENOMEM;
		goto err_release_ports;
	}

	slidebar_input_dev->name = "IdeaPad Slidebar";
	slidebar_input_dev->id.bustype = BUS_HOST;
	slidebar_input_dev->dev.parent = &pdev->dev;
	input_set_capability(slidebar_input_dev, EV_KEY, BTN_TOUCH);
	input_set_capability(slidebar_input_dev, EV_ABS, ABS_X);
	input_set_abs_params(slidebar_input_dev, ABS_X, 0, 0xff, 0, 0);

	err = i8042_install_filter(slidebar_i8042_filter);
	if (err) {
		dev_err(&pdev->dev,
			"Failed to install i8042 filter: %d\n", err);
		goto err_free_dev;
	}

	err = input_register_device(slidebar_input_dev);
	if (err) {
		dev_err(&pdev->dev,
			"Failed to register input device: %d\n", err);
		goto err_remove_filter;
	}

	return 0;

err_remove_filter:
	i8042_remove_filter(slidebar_i8042_filter);
err_free_dev:
	input_free_device(slidebar_input_dev);
err_release_ports:
	release_region(IDEAPAD_BASE, 3);
	return err;
}

static int ideapad_remove(struct platform_device *pdev)
{
	i8042_remove_filter(slidebar_i8042_filter);
	input_unregister_device(slidebar_input_dev);
	release_region(IDEAPAD_BASE, 3);

	return 0;
}

static struct platform_driver slidebar_drv = {
	.driver = {
		.name = "ideapad_slidebar",
	},
	.remove = ideapad_remove,
};

static int __init ideapad_dmi_check(const struct dmi_system_id *id)
{
	pr_info("Laptop model '%s'\n", id->ident);
	return 1;
}

static const struct dmi_system_id ideapad_dmi[] __initconst = {
	{
		.ident = "Lenovo IdeaPad Y550",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
			DMI_MATCH(DMI_PRODUCT_NAME, "20017"),
			DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo IdeaPad Y550")
		},
		.callback = ideapad_dmi_check
	},
	{
		.ident = "Lenovo IdeaPad Y550P",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
			DMI_MATCH(DMI_PRODUCT_NAME, "20035"),
			DMI_MATCH(DMI_PRODUCT_VERSION, "Lenovo IdeaPad Y550P")
		},
		.callback = ideapad_dmi_check
	},
	{ NULL, }
};
MODULE_DEVICE_TABLE(dmi, ideapad_dmi);

static int __init slidebar_init(void)
{
	int err;

	if (!force && !dmi_check_system(ideapad_dmi)) {
		pr_err("DMI does not match\n");
		return -ENODEV;
	}

	slidebar_platform_dev = platform_device_alloc("ideapad_slidebar", -1);
	if (!slidebar_platform_dev) {
		pr_err("Not enough memory\n");
		return -ENOMEM;
	}

	slidebar_platform_dev->dev.groups = ideapad_attr_groups;

	err = platform_device_add(slidebar_platform_dev);
	if (err) {
		pr_err("Failed to register platform device\n");
		goto err_free_dev;
	}

	err = platform_driver_probe(&slidebar_drv, ideapad_probe);
	if (err) {
		pr_err("Failed to register platform driver\n");
		goto err_delete_dev;
	}

	return 0;

err_delete_dev:
	platform_device_del(slidebar_platform_dev);
err_free_dev:
	platform_device_put(slidebar_platform_dev);
	return err;
}

static void __exit slidebar_exit(void)
{
	platform_device_unregister(slidebar_platform_dev);
	platform_driver_unregister(&slidebar_drv);
}

module_init(slidebar_init);
module_exit(slidebar_exit);

MODULE_AUTHOR("Andrey Moiseev <o2g.org.ru@gmail.com>");
MODULE_DESCRIPTION("Slidebar input support for some Lenovo IdeaPad laptops");
MODULE_LICENSE("GPL");