/*
   * Focaltech TouchPad PS/2 mouse driver
   *
   * Copyright (c) 2014 Red Hat Inc.
   * Copyright (c) 2014 Mathias Gottschlag <mgottschlag@gmail.com>
   *
   * 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.
   *
   * Red Hat authors:
   *
   * Hans de Goede <hdegoede@redhat.com>
   */
  
  
  #include <linux/device.h>
  #include <linux/libps2.h>
  #include <linux/input/mt.h>
  #include <linux/serio.h>
  #include <linux/slab.h>
  #include "psmouse.h"
  #include "focaltech.h"
  
  static const char * const focaltech_pnp_ids[] = {
  	"FLT0101",
  	"FLT0102",
  	"FLT0103",
  	NULL
  };
  
  /*
   * Even if the kernel is built without support for Focaltech PS/2 touchpads (or
   * when the real driver fails to recognize the device), we still have to detect
   * them in order to avoid further detection attempts confusing the touchpad.
   * This way it at least works in PS/2 mouse compatibility mode.
   */
  int focaltech_detect(struct psmouse *psmouse, bool set_properties)
  {
  	if (!psmouse_matches_pnp_id(psmouse, focaltech_pnp_ids))
  		return -ENODEV;
  
  	if (set_properties) {
  		psmouse->vendor = "FocalTech";
  		psmouse->name = "FocalTech Touchpad";
  	}
  
  	return 0;
  }
  
  static void focaltech_reset(struct psmouse *psmouse)
  {
  	ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_RESET_DIS);
  	psmouse_reset(psmouse);
  }
  
  #ifdef CONFIG_MOUSE_PS2_FOCALTECH
  
  /*
   * Packet types - the numbers are not consecutive, so we might be missing
   * something here.
   */
  #define FOC_TOUCH 0x3 /* bitmap of active fingers */
  #define FOC_ABS 0x6 /* absolute position of one finger */
  #define FOC_REL 0x9 /* relative position of 1-2 fingers */
  
  #define FOC_MAX_FINGERS 5
  
  /*
   * Current state of a single finger on the touchpad.
   */
  struct focaltech_finger_state {
  	/* The touchpad has generated a touch event for the finger */
  	bool active;
  
  	/*
  	 * The touchpad has sent position data for the finger. The
  	 * flag is 0 when the finger is not active, and there is a
  	 * time between the first touch event for the finger and the
  	 * following absolute position packet for the finger where the
  	 * touchpad has declared the finger to be valid, but we do not
  	 * have any valid position yet.
  	 */
  	bool valid;
  
  	/*
  	 * Absolute position (from the bottom left corner) of the
  	 * finger.
  	 */
  	unsigned int x;
  	unsigned int y;
  };
  
  /*
   * Description of the current state of the touchpad hardware.
   */
  struct focaltech_hw_state {
  	/*
  	 * The touchpad tracks the positions of the fingers for us,
  	 * the array indices correspond to the finger indices returned
  	 * in the report packages.
  	 */
  	struct focaltech_finger_state fingers[FOC_MAX_FINGERS];
  
  	/*
  	 * Finger width 0-7 and 15 for a very big contact area.
  	 * 15 value stays until the finger is released.
  	 * Width is reported only in absolute packets.
  	 * Since hardware reports width only for last touching finger,
  	 * there is no need to store width for every specific finger,
  	 * so we keep only last value reported.
  	 */
  	unsigned int width;
  
  	/* True if the clickpad has been pressed. */
  	bool pressed;
  };
  
  struct focaltech_data {
  	unsigned int x_max, y_max;
  	struct focaltech_hw_state state;
  };
  
  static void focaltech_report_state(struct psmouse *psmouse)
  {
  	struct focaltech_data *priv = psmouse->private;
  	struct focaltech_hw_state *state = &priv->state;
  	struct input_dev *dev = psmouse->dev;
  	int i;
  
  	for (i = 0; i < FOC_MAX_FINGERS; i++) {
  		struct focaltech_finger_state *finger = &state->fingers[i];
  		bool active = finger->active && finger->valid;
  
  		input_mt_slot(dev, i);
  		input_mt_report_slot_state(dev, MT_TOOL_FINGER, active);
  		if (active) {
  			unsigned int clamped_x, clamped_y;
  			/*
  			 * The touchpad might report invalid data, so we clamp
  			 * the resulting values so that we do not confuse
  			 * userspace.
  			 */
  			clamped_x = clamp(finger->x, 0U, priv->x_max);
  			clamped_y = clamp(finger->y, 0U, priv->y_max);
  			input_report_abs(dev, ABS_MT_POSITION_X, clamped_x);
  			input_report_abs(dev, ABS_MT_POSITION_Y,
  					 priv->y_max - clamped_y);
  			input_report_abs(dev, ABS_TOOL_WIDTH, state->width);
  		}
  	}
  	input_mt_report_pointer_emulation(dev, true);
  
  	input_report_key(psmouse->dev, BTN_LEFT, state->pressed);
  	input_sync(psmouse->dev);
  }
  
  static void focaltech_process_touch_packet(struct psmouse *psmouse,
  					   unsigned char *packet)
  {
  	struct focaltech_data *priv = psmouse->private;
  	struct focaltech_hw_state *state = &priv->state;
  	unsigned char fingers = packet[1];
  	int i;
  
  	state->pressed = (packet[0] >> 4) & 1;
  
  	/* the second byte contains a bitmap of all fingers touching the pad */
  	for (i = 0; i < FOC_MAX_FINGERS; i++) {
  		state->fingers[i].active = fingers & 0x1;
  		if (!state->fingers[i].active) {
  			/*
  			 * Even when the finger becomes active again, we still
  			 * will have to wait for the first valid position.
  			 */
  			state->fingers[i].valid = false;
  		}
  		fingers >>= 1;
  	}
  }
  
  static void focaltech_process_abs_packet(struct psmouse *psmouse,
  					 unsigned char *packet)
  {
  	struct focaltech_data *priv = psmouse->private;
  	struct focaltech_hw_state *state = &priv->state;
  	unsigned int finger;
  
  	finger = (packet[1] >> 4) - 1;
  	if (finger >= FOC_MAX_FINGERS) {
  		psmouse_err(psmouse, "Invalid finger in abs packet: %d
  ",
  			    finger);
  		return;
  	}
  
  	state->pressed = (packet[0] >> 4) & 1;
  
  	state->fingers[finger].x = ((packet[1] & 0xf) << 8) | packet[2];
  	state->fingers[finger].y = (packet[3] << 8) | packet[4];
  	state->width = packet[5] >> 4;
  	state->fingers[finger].valid = true;
  }
  
  static void focaltech_process_rel_packet(struct psmouse *psmouse,
  					 unsigned char *packet)
  {
  	struct focaltech_data *priv = psmouse->private;
  	struct focaltech_hw_state *state = &priv->state;
  	int finger1, finger2;
  
  	state->pressed = packet[0] >> 7;
  	finger1 = ((packet[0] >> 4) & 0x7) - 1;
  	if (finger1 < FOC_MAX_FINGERS) {
  		state->fingers[finger1].x += (char)packet[1];
  		state->fingers[finger1].y += (char)packet[2];
  	} else {
  		psmouse_err(psmouse, "First finger in rel packet invalid: %d
  ",
  			    finger1);
  	}
  
  	/*
  	 * If there is an odd number of fingers, the last relative
  	 * packet only contains one finger. In this case, the second
  	 * finger index in the packet is 0 (we subtract 1 in the lines
  	 * above to create array indices, so the finger will overflow
  	 * and be above FOC_MAX_FINGERS).
  	 */
  	finger2 = ((packet[3] >> 4) & 0x7) - 1;
  	if (finger2 < FOC_MAX_FINGERS) {
  		state->fingers[finger2].x += (char)packet[4];
  		state->fingers[finger2].y += (char)packet[5];
  	}
  }
  
  static void focaltech_process_packet(struct psmouse *psmouse)
  {
  	unsigned char *packet = psmouse->packet;
  
  	switch (packet[0] & 0xf) {
  	case FOC_TOUCH:
  		focaltech_process_touch_packet(psmouse, packet);
  		break;
  
  	case FOC_ABS:
  		focaltech_process_abs_packet(psmouse, packet);
  		break;
  
  	case FOC_REL:
  		focaltech_process_rel_packet(psmouse, packet);
  		break;
  
  	default:
  		psmouse_err(psmouse, "Unknown packet type: %02x
  ", packet[0]);
  		break;
  	}
  
  	focaltech_report_state(psmouse);
  }
  
  static psmouse_ret_t focaltech_process_byte(struct psmouse *psmouse)
  {
  	if (psmouse->pktcnt >= 6) { /* Full packet received */
  		focaltech_process_packet(psmouse);
  		return PSMOUSE_FULL_PACKET;
  	}
  
  	/*
  	 * We might want to do some validation of the data here, but
  	 * we do not know the protocol well enough
  	 */
  	return PSMOUSE_GOOD_DATA;
  }
  
  static int focaltech_switch_protocol(struct psmouse *psmouse)
  {
  	struct ps2dev *ps2dev = &psmouse->ps2dev;
  	unsigned char param[3];
  
  	param[0] = 0;
  	if (ps2_command(ps2dev, param, 0x10f8))
  		return -EIO;
  
  	if (ps2_command(ps2dev, param, 0x10f8))
  		return -EIO;
  
  	if (ps2_command(ps2dev, param, 0x10f8))
  		return -EIO;
  
  	param[0] = 1;
  	if (ps2_command(ps2dev, param, 0x10f8))
  		return -EIO;
  
  	if (ps2_command(ps2dev, param, PSMOUSE_CMD_SETSCALE11))
  		return -EIO;
  
  	if (ps2_command(ps2dev, param, PSMOUSE_CMD_ENABLE))
  		return -EIO;
  
  	return 0;
  }
  
  static void focaltech_disconnect(struct psmouse *psmouse)
  {
  	focaltech_reset(psmouse);
  	kfree(psmouse->private);
  	psmouse->private = NULL;
  }
  
  static int focaltech_reconnect(struct psmouse *psmouse)
  {
  	int error;
  
  	focaltech_reset(psmouse);
  
  	error = focaltech_switch_protocol(psmouse);
  	if (error) {
  		psmouse_err(psmouse, "Unable to initialize the device
  ");
  		return error;
  	}
  
  	return 0;
  }
  
  static void focaltech_set_input_params(struct psmouse *psmouse)
  {
  	struct input_dev *dev = psmouse->dev;
  	struct focaltech_data *priv = psmouse->private;
  
  	/*
  	 * Undo part of setup done for us by psmouse core since touchpad
  	 * is not a relative device.
  	 */
  	__clear_bit(EV_REL, dev->evbit);
  	__clear_bit(REL_X, dev->relbit);
  	__clear_bit(REL_Y, dev->relbit);
  	__clear_bit(BTN_RIGHT, dev->keybit);
  	__clear_bit(BTN_MIDDLE, dev->keybit);
  
  	/*
  	 * Now set up our capabilities.
  	 */
  	__set_bit(EV_ABS, dev->evbit);
  	input_set_abs_params(dev, ABS_MT_POSITION_X, 0, priv->x_max, 0, 0);
  	input_set_abs_params(dev, ABS_MT_POSITION_Y, 0, priv->y_max, 0, 0);
  	input_set_abs_params(dev, ABS_TOOL_WIDTH, 0, 15, 0, 0);
  	input_mt_init_slots(dev, 5, INPUT_MT_POINTER);
  	__set_bit(INPUT_PROP_BUTTONPAD, dev->propbit);
  }
  
  static int focaltech_read_register(struct ps2dev *ps2dev, int reg,
  				   unsigned char *param)
  {
  	if (ps2_command(ps2dev, param, PSMOUSE_CMD_SETSCALE11))
  		return -EIO;
  
  	param[0] = 0;
  	if (ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES))
  		return -EIO;
  
  	if (ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES))
  		return -EIO;
  
  	if (ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES))
  		return -EIO;
  
  	param[0] = reg;
  	if (ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES))
  		return -EIO;
  
  	if (ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO))
  		return -EIO;
  
  	return 0;
  }
  
  static int focaltech_read_size(struct psmouse *psmouse)
  {
  	struct ps2dev *ps2dev = &psmouse->ps2dev;
  	struct focaltech_data *priv = psmouse->private;
  	char param[3];
  
  	if (focaltech_read_register(ps2dev, 2, param))
  		return -EIO;
  
  	/* not sure whether this is 100% correct */
  	priv->x_max = (unsigned char)param[1] * 128;
  	priv->y_max = (unsigned char)param[2] * 128;
  
  	return 0;
  }
  
  void focaltech_set_resolution(struct psmouse *psmouse, unsigned int resolution)
  {
  	/* not supported yet */
  }
  
  static void focaltech_set_rate(struct psmouse *psmouse, unsigned int rate)
  {
  	/* not supported yet */
  }
  
  static void focaltech_set_scale(struct psmouse *psmouse,
  				enum psmouse_scale scale)
  {
  	/* not supported yet */
  }
  
  int focaltech_init(struct psmouse *psmouse)
  {
  	struct focaltech_data *priv;
  	int error;
  
  	psmouse->private = priv = kzalloc(sizeof(struct focaltech_data),
  					  GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;
  
  	focaltech_reset(psmouse);
  
  	error = focaltech_read_size(psmouse);
  	if (error) {
  		psmouse_err(psmouse,
  			    "Unable to read the size of the touchpad
  ");
  		goto fail;
  	}
  
  	error = focaltech_switch_protocol(psmouse);
  	if (error) {
  		psmouse_err(psmouse, "Unable to initialize the device
  ");
  		goto fail;
  	}
  
  	focaltech_set_input_params(psmouse);
  
  	psmouse->protocol_handler = focaltech_process_byte;
  	psmouse->pktsize = 6;
  	psmouse->disconnect = focaltech_disconnect;
  	psmouse->reconnect = focaltech_reconnect;
  	psmouse->cleanup = focaltech_reset;
  	/* resync is not supported yet */
  	psmouse->resync_time = 0;
  	/*
  	 * rate/resolution/scale changes are not supported yet, and
  	 * the generic implementations of these functions seem to
  	 * confuse some touchpads
  	 */
  	psmouse->set_resolution = focaltech_set_resolution;
  	psmouse->set_rate = focaltech_set_rate;
  	psmouse->set_scale = focaltech_set_scale;
  
  	return 0;
  
  fail:
  	focaltech_reset(psmouse);
  	kfree(priv);
  	return error;
  }
  
  #else /* CONFIG_MOUSE_PS2_FOCALTECH */
  
  int focaltech_init(struct psmouse *psmouse)
  {
  	focaltech_reset(psmouse);
  
  	return 0;
  }
  
  #endif /* CONFIG_MOUSE_PS2_FOCALTECH */