/*
 * 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;
}

#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\n",
                            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\n",
                            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\n", 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_reset(struct psmouse *psmouse)
{
        ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_RESET_DIS);
        psmouse_reset(psmouse);
}

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\n");
                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\n");
                goto fail;
        }

        error = focaltech_switch_protocol(psmouse);
        if (error) {
                psmouse_err(psmouse, "Unable to initialize the device\n");
                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;
}
#endif /* CONFIG_MOUSE_PS2_FOCALTECH */