/*
   * Wacom protocol 4 serial tablet driver
   *
   * Copyright 2014      Hans de Goede <hdegoede@redhat.com>
   * Copyright 2011-2012 Julian Squires <julian@cipht.net>
   *
   * 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 of 2 of the License, or (at your
   * option) any later version. See the file COPYING in the main directory of
   * this archive for more details.
   *
   * Many thanks to Bill Seremetis, without whom PenPartner support
   * would not have been possible. Thanks to Patrick Mahoney.
   *
   * This driver was developed with reference to much code written by others,
   * particularly:
   *  - elo, gunze drivers by Vojtech Pavlik <vojtech@ucw.cz>;
   *  - wacom_w8001 driver by Jaya Kumar <jayakumar.lkml@gmail.com>;
   *  - the USB wacom input driver, credited to many people
   *    (see drivers/input/tablet/wacom.h);
   *  - new and old versions of linuxwacom / xf86-input-wacom credited to
   *    Frederic Lepied, France. <Lepied@XFree86.org> and
   *    Ping Cheng, Wacom. <pingc@wacom.com>;
   *  - and xf86wacom.c (a presumably ancient version of the linuxwacom code),
   *    by Frederic Lepied and Raph Levien <raph@gtk.org>.
   *
   * To do:
   *  - support pad buttons; (requires access to a model with pad buttons)
   *  - support (protocol 4-style) tilt (requires access to a > 1.4 rom model)
   */
  
  /*
   * Wacom serial protocol 4 documentation taken from linuxwacom-0.9.9 code,
   * protocol 4 uses 7 or 9 byte of data in the following format:
   *
   *	Byte 1
   *	bit 7  Sync bit always 1
   *	bit 6  Pointing device detected
   *	bit 5  Cursor = 0 / Stylus = 1
   *	bit 4  Reserved
   *	bit 3  1 if a button on the pointing device has been pressed
   *	bit 2  P0 (optional)
   *	bit 1  X15
   *	bit 0  X14
   *
   *	Byte 2
   *	bit 7  Always 0
   *	bits 6-0 = X13 - X7
   *
   *	Byte 3
   *	bit 7  Always 0
   *	bits 6-0 = X6 - X0
   *
   *	Byte 4
   *	bit 7  Always 0
   *	bit 6  B3
   *	bit 5  B2
   *	bit 4  B1
   *	bit 3  B0
   *	bit 2  P1 (optional)
   *	bit 1  Y15
   *	bit 0  Y14
   *
   *	Byte 5
   *	bit 7  Always 0
   *	bits 6-0 = Y13 - Y7
   *
   *	Byte 6
   *	bit 7  Always 0
   *	bits 6-0 = Y6 - Y0
   *
   *	Byte 7
   *	bit 7 Always 0
   *	bit 6  Sign of pressure data; or wheel-rel for cursor tool
   *	bit 5  P7; or REL1 for cursor tool
   *	bit 4  P6; or REL0 for cursor tool
   *	bit 3  P5
   *	bit 2  P4
   *	bit 1  P3
   *	bit 0  P2
   *
   *	byte 8 and 9 are optional and present only
   *	in tilt mode.
   *
   *	Byte 8
   *	bit 7 Always 0
   *	bit 6 Sign of tilt X
   *	bit 5  Xt6
   *	bit 4  Xt5
   *	bit 3  Xt4
   *	bit 2  Xt3
   *	bit 1  Xt2
   *	bit 0  Xt1
   *
   *	Byte 9
   *	bit 7 Always 0
   *	bit 6 Sign of tilt Y
   *	bit 5  Yt6
   *	bit 4  Yt5
   *	bit 3  Yt4
   *	bit 2  Yt3
   *	bit 1  Yt2
   *	bit 0  Yt1
   */
  
  #include <linux/completion.h>
  #include <linux/init.h>
  #include <linux/input.h>
  #include <linux/interrupt.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/serio.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  
  MODULE_AUTHOR("Julian Squires <julian@cipht.net>, Hans de Goede <hdegoede@redhat.com>");
  MODULE_DESCRIPTION("Wacom protocol 4 serial tablet driver");
  MODULE_LICENSE("GPL");
  
  #define REQUEST_MODEL_AND_ROM_VERSION	"~#"
  #define REQUEST_MAX_COORDINATES		"~C\r"
  #define REQUEST_CONFIGURATION_STRING	"~R\r"
  #define REQUEST_RESET_TO_PROTOCOL_IV	"\r#"
  /*
   * Note: sending "\r$\r" causes at least the Digitizer II to send
   * packets in ASCII instead of binary.  "\r#" seems to undo that.
   */
  
  #define COMMAND_START_SENDING_PACKETS		"ST\r"
  #define COMMAND_STOP_SENDING_PACKETS		"SP\r"
  #define COMMAND_MULTI_MODE_INPUT		"MU1\r"
  #define COMMAND_ORIGIN_IN_UPPER_LEFT		"OC1\r"
  #define COMMAND_ENABLE_ALL_MACRO_BUTTONS	"~M0\r"
  #define COMMAND_DISABLE_GROUP_1_MACRO_BUTTONS	"~M1\r"
  #define COMMAND_TRANSMIT_AT_MAX_RATE		"IT0\r"
  #define COMMAND_DISABLE_INCREMENTAL_MODE	"IN0\r"
  #define COMMAND_ENABLE_CONTINUOUS_MODE		"SR\r"
  #define COMMAND_ENABLE_PRESSURE_MODE		"PH1\r"
  #define COMMAND_Z_FILTER			"ZF1\r"
  
  /* Note that this is a protocol 4 packet without tilt information. */
  #define PACKET_LENGTH		7
  #define DATA_SIZE		32
  
  /* flags */
  #define F_COVERS_SCREEN		0x01
  #define F_HAS_STYLUS2		0x02
  #define F_HAS_SCROLLWHEEL	0x04
  
  /* device IDs */
  #define STYLUS_DEVICE_ID	0x02
  #define CURSOR_DEVICE_ID	0x06
  #define ERASER_DEVICE_ID	0x0A
  
  enum { STYLUS = 1, ERASER, CURSOR };
  
  static const struct {
  	int device_id;
  	int input_id;
  } tools[] = {
  	{ 0, 0 },
  	{ STYLUS_DEVICE_ID, BTN_TOOL_PEN },
  	{ ERASER_DEVICE_ID, BTN_TOOL_RUBBER },
  	{ CURSOR_DEVICE_ID, BTN_TOOL_MOUSE },
  };
  
  struct wacom {
  	struct input_dev *dev;
  	struct completion cmd_done;
  	int result;
  	u8 expect;
  	u8 eraser_mask;
  	unsigned int extra_z_bits;
  	unsigned int flags;
  	unsigned int res_x, res_y;
  	unsigned int max_x, max_y;
  	unsigned int tool;
  	unsigned int idx;
  	u8 data[DATA_SIZE];
  	char phys[32];
  };
  
  enum {
  	MODEL_CINTIQ		= 0x504C, /* PL */
  	MODEL_CINTIQ2		= 0x4454, /* DT */
  	MODEL_DIGITIZER_II	= 0x5544, /* UD */
  	MODEL_GRAPHIRE		= 0x4554, /* ET */
  	MODEL_PENPARTNER	= 0x4354, /* CT */
  };
  
  static void wacom_handle_model_response(struct wacom *wacom)
  {
  	int major_v, minor_v, r = 0;
  	char *p;
  
  	p = strrchr(wacom->data, 'V');
  	if (p)
  		r = sscanf(p + 1, "%u.%u", &major_v, &minor_v);
  	if (r != 2)
  		major_v = minor_v = 0;
  
  	switch (wacom->data[2] << 8 | wacom->data[3]) {
  	case MODEL_CINTIQ:	/* UNTESTED */
  	case MODEL_CINTIQ2:
  		if ((wacom->data[2] << 8 | wacom->data[3]) == MODEL_CINTIQ) {
  			wacom->dev->name = "Wacom Cintiq";
  			wacom->dev->id.version = MODEL_CINTIQ;
  		} else {
  			wacom->dev->name = "Wacom Cintiq II";
  			wacom->dev->id.version = MODEL_CINTIQ2;
  		}
  		wacom->res_x = 508;
  		wacom->res_y = 508;
  
  		switch (wacom->data[5] << 8 | wacom->data[6]) {
  		case 0x3731: /* PL-710 */
  			wacom->res_x = 2540;
  			wacom->res_y = 2540;
  			/* fall through */
  		case 0x3535: /* PL-550 */
  		case 0x3830: /* PL-800 */
  			wacom->extra_z_bits = 2;
  		}
  
  		wacom->flags = F_COVERS_SCREEN;
  		break;
  
  	case MODEL_PENPARTNER:
  		wacom->dev->name = "Wacom Penpartner";
  		wacom->dev->id.version = MODEL_PENPARTNER;
  		wacom->res_x = 1000;
  		wacom->res_y = 1000;
  		break;
  
  	case MODEL_GRAPHIRE:
  		wacom->dev->name = "Wacom Graphire";
  		wacom->dev->id.version = MODEL_GRAPHIRE;
  		wacom->res_x = 1016;
  		wacom->res_y = 1016;
  		wacom->max_x = 5103;
  		wacom->max_y = 3711;
  		wacom->extra_z_bits = 2;
  		wacom->eraser_mask = 0x08;
  		wacom->flags = F_HAS_STYLUS2 | F_HAS_SCROLLWHEEL;
  		break;
  
  	case MODEL_DIGITIZER_II:
  		wacom->dev->name = "Wacom Digitizer II";
  		wacom->dev->id.version = MODEL_DIGITIZER_II;
  		if (major_v == 1 && minor_v <= 2)
  			wacom->extra_z_bits = 0; /* UNTESTED */
  		break;
  
  	default:
  		dev_err(&wacom->dev->dev, "Unsupported Wacom model %s
  ",
  			wacom->data);
  		wacom->result = -ENODEV;
  		return;
  	}
  
  	dev_info(&wacom->dev->dev, "%s tablet, version %u.%u
  ",
  		 wacom->dev->name, major_v, minor_v);
  }
  
  static void wacom_handle_configuration_response(struct wacom *wacom)
  {
  	int r, skip;
  
  	dev_dbg(&wacom->dev->dev, "Configuration string: %s
  ", wacom->data);
  	r = sscanf(wacom->data, "~R%x,%u,%u,%u,%u", &skip, &skip, &skip,
  		   &wacom->res_x, &wacom->res_y);
  	if (r != 5)
  		dev_warn(&wacom->dev->dev, "could not get resolution
  ");
  }
  
  static void wacom_handle_coordinates_response(struct wacom *wacom)
  {
  	int r;
  
  	dev_dbg(&wacom->dev->dev, "Coordinates string: %s
  ", wacom->data);
  	r = sscanf(wacom->data, "~C%u,%u", &wacom->max_x, &wacom->max_y);
  	if (r != 2)
  		dev_warn(&wacom->dev->dev, "could not get max coordinates
  ");
  }
  
  static void wacom_handle_response(struct wacom *wacom)
  {
  	if (wacom->data[0] != '~' || wacom->data[1] != wacom->expect) {
  		dev_err(&wacom->dev->dev,
  			"Wacom got an unexpected response: %s
  ", wacom->data);
  		wacom->result = -EIO;
  	} else {
  		wacom->result = 0;
  
  		switch (wacom->data[1]) {
  		case '#':
  			wacom_handle_model_response(wacom);
  			break;
  		case 'R':
  			wacom_handle_configuration_response(wacom);
  			break;
  		case 'C':
  			wacom_handle_coordinates_response(wacom);
  			break;
  		}
  	}
  
  	complete(&wacom->cmd_done);
  }
  
  static void wacom_handle_packet(struct wacom *wacom)
  {
  	u8 in_proximity_p, stylus_p, button;
  	unsigned int tool;
  	int x, y, z;
  
  	in_proximity_p = wacom->data[0] & 0x40;
  	stylus_p = wacom->data[0] & 0x20;
  	button = (wacom->data[3] & 0x78) >> 3;
  	x = (wacom->data[0] & 3) << 14 | wacom->data[1]<<7 | wacom->data[2];
  	y = (wacom->data[3] & 3) << 14 | wacom->data[4]<<7 | wacom->data[5];
  
  	if (in_proximity_p && stylus_p) {
  		z = wacom->data[6] & 0x7f;
  		if (wacom->extra_z_bits >= 1)
  			z = z << 1 | (wacom->data[3] & 0x4) >> 2;
  		if (wacom->extra_z_bits > 1)
  			z = z << 1 | (wacom->data[0] & 0x4) >> 2;
  		z = z ^ (0x40 << wacom->extra_z_bits);
  	} else {
  		z = -1;
  	}
  
  	if (stylus_p)
  		tool = (button & wacom->eraser_mask) ? ERASER : STYLUS;
  	else
  		tool = CURSOR;
  
  	if (tool != wacom->tool && wacom->tool != 0) {
  		input_report_key(wacom->dev, tools[wacom->tool].input_id, 0);
  		input_sync(wacom->dev);
  	}
  	wacom->tool = tool;
  
  	input_report_key(wacom->dev, tools[tool].input_id, in_proximity_p);
  	input_report_abs(wacom->dev, ABS_MISC,
  			 in_proximity_p ? tools[tool].device_id : 0);
  	input_report_abs(wacom->dev, ABS_X, x);
  	input_report_abs(wacom->dev, ABS_Y, y);
  	input_report_abs(wacom->dev, ABS_PRESSURE, z);
  	if (stylus_p) {
  		input_report_key(wacom->dev, BTN_TOUCH, button & 1);
  		input_report_key(wacom->dev, BTN_STYLUS, button & 2);
  		input_report_key(wacom->dev, BTN_STYLUS2, button & 4);
  	} else {
  		input_report_key(wacom->dev, BTN_LEFT, button & 1);
  		input_report_key(wacom->dev, BTN_RIGHT, button & 2);
  		input_report_key(wacom->dev, BTN_MIDDLE, button & 4);
  		/* handle relative wheel for non-stylus device */
  		z = (wacom->data[6] & 0x30) >> 4;
  		if (wacom->data[6] & 0x40)
  			z = -z;
  		input_report_rel(wacom->dev, REL_WHEEL, z);
  	}
  	input_sync(wacom->dev);
  }
  
  static void wacom_clear_data_buf(struct wacom *wacom)
  {
  	memset(wacom->data, 0, DATA_SIZE);
  	wacom->idx = 0;
  }
  
  static irqreturn_t wacom_interrupt(struct serio *serio, unsigned char data,
  				   unsigned int flags)
  {
  	struct wacom *wacom = serio_get_drvdata(serio);
  
  	if (data & 0x80)
  		wacom->idx = 0;
  
  	/*
  	 * We're either expecting a carriage return-terminated ASCII
  	 * response string, or a seven-byte packet with the MSB set on
  	 * the first byte.
  	 *
  	 * Note however that some tablets (the PenPartner, for
  	 * example) don't send a carriage return at the end of a
  	 * command.  We handle these by waiting for timeout.
  	 */
  	if (data == '\r' && !(wacom->data[0] & 0x80)) {
  		wacom_handle_response(wacom);
  		wacom_clear_data_buf(wacom);
  		return IRQ_HANDLED;
  	}
  
  	/* Leave place for 0 termination */
  	if (wacom->idx > (DATA_SIZE - 2)) {
  		dev_dbg(&wacom->dev->dev,
  			"throwing away %d bytes of garbage
  ", wacom->idx);
  		wacom_clear_data_buf(wacom);
  	}
  	wacom->data[wacom->idx++] = data;
  
  	if (wacom->idx == PACKET_LENGTH && (wacom->data[0] & 0x80)) {
  		wacom_handle_packet(wacom);
  		wacom_clear_data_buf(wacom);
  	}
  
  	return IRQ_HANDLED;
  }
  
  static void wacom_disconnect(struct serio *serio)
  {
  	struct wacom *wacom = serio_get_drvdata(serio);
  
  	serio_close(serio);
  	serio_set_drvdata(serio, NULL);
  	input_unregister_device(wacom->dev);
  	kfree(wacom);
  }
  
  static int wacom_send(struct serio *serio, const u8 *command)
  {
  	int err = 0;
  
  	for (; !err && *command; command++)
  		err = serio_write(serio, *command);
  
  	return err;
  }
  
  static int wacom_send_setup_string(struct wacom *wacom, struct serio *serio)
  {
  	const u8 *cmd;
  
  	switch (wacom->dev->id.version) {
  	case MODEL_CINTIQ:	/* UNTESTED */
  		cmd = COMMAND_ORIGIN_IN_UPPER_LEFT
  			COMMAND_TRANSMIT_AT_MAX_RATE
  			COMMAND_ENABLE_CONTINUOUS_MODE
  			COMMAND_START_SENDING_PACKETS;
  		break;
  
  	case MODEL_PENPARTNER:
  		cmd = COMMAND_ENABLE_PRESSURE_MODE
  			COMMAND_START_SENDING_PACKETS;
  		break;
  
  	default:
  		cmd = COMMAND_MULTI_MODE_INPUT
  			COMMAND_ORIGIN_IN_UPPER_LEFT
  			COMMAND_ENABLE_ALL_MACRO_BUTTONS
  			COMMAND_DISABLE_GROUP_1_MACRO_BUTTONS
  			COMMAND_TRANSMIT_AT_MAX_RATE
  			COMMAND_DISABLE_INCREMENTAL_MODE
  			COMMAND_ENABLE_CONTINUOUS_MODE
  			COMMAND_Z_FILTER
  			COMMAND_START_SENDING_PACKETS;
  		break;
  	}
  
  	return wacom_send(serio, cmd);
  }
  
  static int wacom_send_and_wait(struct wacom *wacom, struct serio *serio,
  			       const u8 *cmd, const char *desc)
  {
  	int err;
  	unsigned long u;
  
  	wacom->expect = cmd[1];
  	init_completion(&wacom->cmd_done);
  
  	err = wacom_send(serio, cmd);
  	if (err)
  		return err;
  
  	u = wait_for_completion_timeout(&wacom->cmd_done, HZ);
  	if (u == 0) {
  		/* Timeout, process what we've received. */
  		wacom_handle_response(wacom);
  	}
  
  	wacom->expect = 0;
  	return wacom->result;
  }
  
  static int wacom_setup(struct wacom *wacom, struct serio *serio)
  {
  	int err;
  
  	/* Note that setting the link speed is the job of inputattach.
  	 * We assume that reset negotiation has already happened,
  	 * here. */
  	err = wacom_send_and_wait(wacom, serio, REQUEST_MODEL_AND_ROM_VERSION,
  				  "model and version");
  	if (err)
  		return err;
  
  	if (!(wacom->res_x && wacom->res_y)) {
  		err = wacom_send_and_wait(wacom, serio,
  					  REQUEST_CONFIGURATION_STRING,
  					  "configuration string");
  		if (err)
  			return err;
  	}
  
  	if (!(wacom->max_x && wacom->max_y)) {
  		err = wacom_send_and_wait(wacom, serio,
  					  REQUEST_MAX_COORDINATES,
  					  "coordinates string");
  		if (err)
  			return err;
  	}
  
  	return wacom_send_setup_string(wacom, serio);
  }
  
  static int wacom_connect(struct serio *serio, struct serio_driver *drv)
  {
  	struct wacom *wacom;
  	struct input_dev *input_dev;
  	int err = -ENOMEM;
  
  	wacom = kzalloc(sizeof(struct wacom), GFP_KERNEL);
  	input_dev = input_allocate_device();
  	if (!wacom || !input_dev)
  		goto free_device;
  
  	wacom->dev = input_dev;
  	wacom->extra_z_bits = 1;
  	wacom->eraser_mask = 0x04;
  	wacom->tool = wacom->idx = 0;
  	snprintf(wacom->phys, sizeof(wacom->phys), "%s/input0", serio->phys);
  	input_dev->phys = wacom->phys;
  	input_dev->id.bustype = BUS_RS232;
  	input_dev->id.vendor  = SERIO_WACOM_IV;
  	input_dev->id.product = serio->id.extra;
  	input_dev->dev.parent = &serio->dev;
  
  	input_dev->evbit[0] =
  		BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS) | BIT_MASK(EV_REL);
  	set_bit(ABS_MISC, input_dev->absbit);
  	set_bit(BTN_TOOL_PEN, input_dev->keybit);
  	set_bit(BTN_TOOL_RUBBER, input_dev->keybit);
  	set_bit(BTN_TOOL_MOUSE, input_dev->keybit);
  	set_bit(BTN_TOUCH, input_dev->keybit);
  	set_bit(BTN_STYLUS, input_dev->keybit);
  	set_bit(BTN_LEFT, input_dev->keybit);
  	set_bit(BTN_RIGHT, input_dev->keybit);
  	set_bit(BTN_MIDDLE, input_dev->keybit);
  
  	serio_set_drvdata(serio, wacom);
  
  	err = serio_open(serio, drv);
  	if (err)
  		goto free_device;
  
  	err = wacom_setup(wacom, serio);
  	if (err)
  		goto close_serio;
  
  	set_bit(INPUT_PROP_DIRECT, input_dev->propbit);
  	if (!(wacom->flags & F_COVERS_SCREEN))
  		__set_bit(INPUT_PROP_POINTER, input_dev->propbit);
  
  	if (wacom->flags & F_HAS_STYLUS2)
  		__set_bit(BTN_STYLUS2, input_dev->keybit);
  
  	if (wacom->flags & F_HAS_SCROLLWHEEL)
  		__set_bit(REL_WHEEL, input_dev->relbit);
  
  	input_abs_set_res(wacom->dev, ABS_X, wacom->res_x);
  	input_abs_set_res(wacom->dev, ABS_Y, wacom->res_y);
  	input_set_abs_params(wacom->dev, ABS_X, 0, wacom->max_x, 0, 0);
  	input_set_abs_params(wacom->dev, ABS_Y, 0, wacom->max_y, 0, 0);
  	input_set_abs_params(wacom->dev, ABS_PRESSURE, -1,
  			     (1 << (7 + wacom->extra_z_bits)) - 1, 0, 0);
  
  	err = input_register_device(wacom->dev);
  	if (err)
  		goto close_serio;
  
  	return 0;
  
  close_serio:
  	serio_close(serio);
  free_device:
  	serio_set_drvdata(serio, NULL);
  	input_free_device(input_dev);
  	kfree(wacom);
  	return err;
  }
  
  static struct serio_device_id wacom_serio_ids[] = {
  	{
  		.type	= SERIO_RS232,
  		.proto	= SERIO_WACOM_IV,
  		.id	= SERIO_ANY,
  		.extra	= SERIO_ANY,
  	},
  	{ 0 }
  };
  
  MODULE_DEVICE_TABLE(serio, wacom_serio_ids);
  
  static struct serio_driver wacom_drv = {
  	.driver		= {
  		.name	= "wacom_serial4",
  	},
  	.description	= "Wacom protocol 4 serial tablet driver",
  	.id_table	= wacom_serio_ids,
  	.interrupt	= wacom_interrupt,
  	.connect	= wacom_connect,
  	.disconnect	= wacom_disconnect,
  };
  
  module_serio_driver(wacom_drv);