/*
 * OLPC HGPK (XO-1) touchpad PS/2 mouse driver
 *
 * Copyright (c) 2006-2008 One Laptop Per Child
 * Authors:
 *   Zephaniah E. Hull
 *   Andres Salomon <dilinger@debian.org>
 *
 * This driver is partly based on the ALPS driver, which is:
 *
 * Copyright (c) 2003 Neil Brown <neilb@cse.unsw.edu.au>
 * Copyright (c) 2003-2005 Peter Osterlund <petero2@telia.com>
 * Copyright (c) 2004 Dmitry Torokhov <dtor@mail.ru>
 * Copyright (c) 2005 Vojtech Pavlik <vojtech@suse.cz>
 *
 * 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.
 */

/*
 * The spec from ALPS is available from
 * <http://wiki.laptop.org/go/Touch_Pad/Tablet>.  It refers to this
 * device as HGPK (Hybrid GS, PT, and Keymatrix).
 *
 * The earliest versions of the device had simultaneous reporting; that
 * was removed.  After that, the device used the Advanced Mode GS/PT streaming
 * stuff.  That turned out to be too buggy to support, so we've finally
 * switched to Mouse Mode (which utilizes only the center 1/3 of the touchpad).
 */

#define DEBUG
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/module.h>
#include <linux/serio.h>
#include <linux/libps2.h>
#include <linux/delay.h>
#include <asm/olpc.h>

#include "psmouse.h"
#include "hgpk.h"

#define ILLEGAL_XY 999999

static bool tpdebug;
module_param(tpdebug, bool, 0644);
MODULE_PARM_DESC(tpdebug, "enable debugging, dumping packets to KERN_DEBUG.");

static int recalib_delta = 100;
module_param(recalib_delta, int, 0644);
MODULE_PARM_DESC(recalib_delta,
        "packets containing a delta this large will be discarded, and a "
        "recalibration may be scheduled.");

static int jumpy_delay = 20;
module_param(jumpy_delay, int, 0644);
MODULE_PARM_DESC(jumpy_delay,
        "delay (ms) before recal after jumpiness detected");

static int spew_delay = 1;
module_param(spew_delay, int, 0644);
MODULE_PARM_DESC(spew_delay,
        "delay (ms) before recal after packet spew detected");

static int recal_guard_time;
module_param(recal_guard_time, int, 0644);
MODULE_PARM_DESC(recal_guard_time,
        "interval (ms) during which recal will be restarted if packet received");

static int post_interrupt_delay = 40;
module_param(post_interrupt_delay, int, 0644);
MODULE_PARM_DESC(post_interrupt_delay,
        "delay (ms) before recal after recal interrupt detected");

static bool autorecal = true;
module_param(autorecal, bool, 0644);
MODULE_PARM_DESC(autorecal, "enable recalibration in the driver");

static char hgpk_mode_name[16];
module_param_string(hgpk_mode, hgpk_mode_name, sizeof(hgpk_mode_name), 0644);
MODULE_PARM_DESC(hgpk_mode,
        "default hgpk mode: mouse, glidesensor or pentablet");

static int hgpk_default_mode = HGPK_MODE_MOUSE;

static const char * const hgpk_mode_names[] = {
        [HGPK_MODE_MOUSE] = "Mouse",
        [HGPK_MODE_GLIDESENSOR] = "GlideSensor",
        [HGPK_MODE_PENTABLET] = "PenTablet",
};

static int hgpk_mode_from_name(const char *buf, int len)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(hgpk_mode_names); i++) {
                const char *name = hgpk_mode_names[i];
                if (strlen(name) == len && !strncasecmp(name, buf, len))
                        return i;
        }

        return HGPK_MODE_INVALID;
}

/*
 * see if new value is within 20% of half of old value
 */
static int approx_half(int curr, int prev)
{
        int belowhalf, abovehalf;

        if (curr < 5 || prev < 5)
                return 0;

        belowhalf = (prev * 8) / 20;
        abovehalf = (prev * 12) / 20;

        return belowhalf < curr && curr <= abovehalf;
}

/*
 * Throw out oddly large delta packets, and any that immediately follow whose
 * values are each approximately half of the previous.  It seems that the ALPS
 * firmware emits errant packets, and they get averaged out slowly.
 */
static int hgpk_discard_decay_hack(struct psmouse *psmouse, int x, int y)
{
        struct hgpk_data *priv = psmouse->private;
        int avx, avy;
        bool do_recal = false;

        avx = abs(x);
        avy = abs(y);

        /* discard if too big, or half that but > 4 times the prev delta */
        if (avx > recalib_delta ||
                (avx > recalib_delta / 2 && ((avx / 4) > priv->xlast))) {
                psmouse_warn(psmouse, "detected %dpx jump in x\n", x);
                priv->xbigj = avx;
        } else if (approx_half(avx, priv->xbigj)) {
                psmouse_warn(psmouse, "detected secondary %dpx jump in x\n", x);
                priv->xbigj = avx;
                priv->xsaw_secondary++;
        } else {
                if (priv->xbigj && priv->xsaw_secondary > 1)
                        do_recal = true;
                priv->xbigj = 0;
                priv->xsaw_secondary = 0;
        }

        if (avy > recalib_delta ||
                (avy > recalib_delta / 2 && ((avy / 4) > priv->ylast))) {
                psmouse_warn(psmouse, "detected %dpx jump in y\n", y);
                priv->ybigj = avy;
        } else if (approx_half(avy, priv->ybigj)) {
                psmouse_warn(psmouse, "detected secondary %dpx jump in y\n", y);
                priv->ybigj = avy;
                priv->ysaw_secondary++;
        } else {
                if (priv->ybigj && priv->ysaw_secondary > 1)
                        do_recal = true;
                priv->ybigj = 0;
                priv->ysaw_secondary = 0;
        }

        priv->xlast = avx;
        priv->ylast = avy;

        if (do_recal && jumpy_delay) {
                psmouse_warn(psmouse, "scheduling recalibration\n");
                psmouse_queue_work(psmouse, &priv->recalib_wq,
                                msecs_to_jiffies(jumpy_delay));
        }

        return priv->xbigj || priv->ybigj;
}

static void hgpk_reset_spew_detection(struct hgpk_data *priv)
{
        priv->spew_count = 0;
        priv->dupe_count = 0;
        priv->x_tally = 0;
        priv->y_tally = 0;
        priv->spew_flag = NO_SPEW;
}

static void hgpk_reset_hack_state(struct psmouse *psmouse)
{
        struct hgpk_data *priv = psmouse->private;

        priv->abs_x = priv->abs_y = -1;
        priv->xlast = priv->ylast = ILLEGAL_XY;
        priv->xbigj = priv->ybigj = 0;
        priv->xsaw_secondary = priv->ysaw_secondary = 0;
        hgpk_reset_spew_detection(priv);
}

/*
 * We have no idea why this particular hardware bug occurs.  The touchpad
 * will randomly start spewing packets without anything touching the
 * pad.  This wouldn't necessarily be bad, but it's indicative of a
 * severely miscalibrated pad; attempting to use the touchpad while it's
 * spewing means the cursor will jump all over the place, and act "drunk".
 *
 * The packets that are spewed tend to all have deltas between -2 and 2, and
 * the cursor will move around without really going very far.  It will
 * tend to end up in the same location; if we tally up the changes over
 * 100 packets, we end up w/ a final delta of close to 0.  This happens
 * pretty regularly when the touchpad is spewing, and is pretty hard to
 * manually trigger (at least for *my* fingers).  So, it makes a perfect
 * scheme for detecting spews.
 */
static void hgpk_spewing_hack(struct psmouse *psmouse,
                              int l, int r, int x, int y)
{
        struct hgpk_data *priv = psmouse->private;

        /* ignore button press packets; many in a row could trigger
         * a false-positive! */
        if (l || r)
                return;

        /* don't track spew if the workaround feature has been turned off */
        if (!spew_delay)
                return;

        if (abs(x) > 3 || abs(y) > 3) {
                /* no spew, or spew ended */
                hgpk_reset_spew_detection(priv);
                return;
        }

        /* Keep a tally of the overall delta to the cursor position caused by
         * the spew */
        priv->x_tally += x;
        priv->y_tally += y;

        switch (priv->spew_flag) {
        case NO_SPEW:
                /* we're not spewing, but this packet might be the start */
                priv->spew_flag = MAYBE_SPEWING;

                /* fall-through */

        case MAYBE_SPEWING:
                priv->spew_count++;

                if (priv->spew_count < SPEW_WATCH_COUNT)
                        break;

                /* excessive spew detected, request recalibration */
                priv->spew_flag = SPEW_DETECTED;

                /* fall-through */

        case SPEW_DETECTED:
                /* only recalibrate when the overall delta to the cursor
                 * is really small. if the spew is causing significant cursor
                 * movement, it is probably a case of the user moving the
                 * cursor very slowly across the screen. */
                if (abs(priv->x_tally) < 3 && abs(priv->y_tally) < 3) {
                        psmouse_warn(psmouse, "packet spew detected (%d,%d)\n",
                                     priv->x_tally, priv->y_tally);
                        priv->spew_flag = RECALIBRATING;
                        psmouse_queue_work(psmouse, &priv->recalib_wq,
                                           msecs_to_jiffies(spew_delay));
                }

                break;
        case RECALIBRATING:
                /* we already detected a spew and requested a recalibration,
                 * just wait for the queue to kick into action. */
                break;
        }
}

/*
 * HGPK Mouse Mode format (standard mouse format, sans middle button)
 *
 * byte 0:      y-over  x-over  y-neg   x-neg   1       0       swr     swl
 * byte 1:      x7      x6      x5      x4      x3      x2      x1      x0
 * byte 2:      y7      y6      y5      y4      y3      y2      y1      y0
 *
 * swr/swl are the left/right buttons.
 * x-neg/y-neg are the x and y delta negative bits
 * x-over/y-over are the x and y overflow bits
 *
 * ---
 *
 * HGPK Advanced Mode - single-mode format
 *
 * byte 0(PT):  1    1    0    0    1    1     1     1
 * byte 0(GS):  1    1    1    1    1    1     1     1
 * byte 1:      0   x6   x5   x4   x3   x2    x1    x0
 * byte 2(PT):  0    0   x9   x8   x7    ? pt-dsw    0
 * byte 2(GS):  0  x10   x9   x8   x7    ? gs-dsw pt-dsw
 * byte 3:      0   y9   y8   y7    1    0   swr   swl
 * byte 4:      0   y6   y5   y4   y3   y2    y1    y0
 * byte 5:      0   z6   z5   z4   z3   z2    z1    z0
 *
 * ?'s are not defined in the protocol spec, may vary between models.
 *
 * swr/swl are the left/right buttons.
 *
 * pt-dsw/gs-dsw indicate that the pt/gs sensor is detecting a
 * pen/finger
 */
static bool hgpk_is_byte_valid(struct psmouse *psmouse, unsigned char *packet)
{
        struct hgpk_data *priv = psmouse->private;
        int pktcnt = psmouse->pktcnt;
        bool valid;

        switch (priv->mode) {
        case HGPK_MODE_MOUSE:
                valid = (packet[0] & 0x0C) == 0x08;
                break;

        case HGPK_MODE_GLIDESENSOR:
                valid = pktcnt == 1 ?
                        packet[0] == HGPK_GS : !(packet[pktcnt - 1] & 0x80);
                break;

        case HGPK_MODE_PENTABLET:
                valid = pktcnt == 1 ?
                        packet[0] == HGPK_PT : !(packet[pktcnt - 1] & 0x80);
                break;

        default:
                valid = false;
                break;
        }

        if (!valid)
                psmouse_dbg(psmouse,
                            "bad data, mode %d (%d) %*ph\n",
                            priv->mode, pktcnt, 6, psmouse->packet);

        return valid;
}

static void hgpk_process_advanced_packet(struct psmouse *psmouse)
{
        struct hgpk_data *priv = psmouse->private;
        struct input_dev *idev = psmouse->dev;
        unsigned char *packet = psmouse->packet;
        int down = !!(packet[2] & 2);
        int left = !!(packet[3] & 1);
        int right = !!(packet[3] & 2);
        int x = packet[1] | ((packet[2] & 0x78) << 4);
        int y = packet[4] | ((packet[3] & 0x70) << 3);

        if (priv->mode == HGPK_MODE_GLIDESENSOR) {
                int pt_down = !!(packet[2] & 1);
                int finger_down = !!(packet[2] & 2);
                int z = packet[5];

                input_report_abs(idev, ABS_PRESSURE, z);
                if (tpdebug)
                        psmouse_dbg(psmouse, "pd=%d fd=%d z=%d",
                                    pt_down, finger_down, z);
        } else {
                /*
                 * PenTablet mode does not report pressure, so we don't
                 * report it here
                 */
                if (tpdebug)
                        psmouse_dbg(psmouse, "pd=%d ", down);
        }

        if (tpdebug)
                psmouse_dbg(psmouse, "l=%d r=%d x=%d y=%d\n",
                            left, right, x, y);

        input_report_key(idev, BTN_TOUCH, down);
        input_report_key(idev, BTN_LEFT, left);
        input_report_key(idev, BTN_RIGHT, right);

        /*
         * If this packet says that the finger was removed, reset our position
         * tracking so that we don't erroneously detect a jump on next press.
         */
        if (!down) {
                hgpk_reset_hack_state(psmouse);
                goto done;
        }

        /*
         * Weed out duplicate packets (we get quite a few, and they mess up
         * our jump detection)
         */
        if (x == priv->abs_x && y == priv->abs_y) {
                if (++priv->dupe_count > SPEW_WATCH_COUNT) {
                        if (tpdebug)
                                psmouse_dbg(psmouse, "hard spew detected\n");
                        priv->spew_flag = RECALIBRATING;
                        psmouse_queue_work(psmouse, &priv->recalib_wq,
                                           msecs_to_jiffies(spew_delay));
                }
                goto done;
        }

        /* not a duplicate, continue with position reporting */
        priv->dupe_count = 0;

        /* Don't apply hacks in PT mode, it seems reliable */
        if (priv->mode != HGPK_MODE_PENTABLET && priv->abs_x != -1) {
                int x_diff = priv->abs_x - x;
                int y_diff = priv->abs_y - y;
                if (hgpk_discard_decay_hack(psmouse, x_diff, y_diff)) {
                        if (tpdebug)
                                psmouse_dbg(psmouse, "discarding\n");
                        goto done;
                }
                hgpk_spewing_hack(psmouse, left, right, x_diff, y_diff);
        }

        input_report_abs(idev, ABS_X, x);
        input_report_abs(idev, ABS_Y, y);
        priv->abs_x = x;
        priv->abs_y = y;

done:
        input_sync(idev);
}

static void hgpk_process_simple_packet(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        unsigned char *packet = psmouse->packet;
        int left = packet[0] & 1;
        int right = (packet[0] >> 1) & 1;
        int x = packet[1] - ((packet[0] << 4) & 0x100);
        int y = ((packet[0] << 3) & 0x100) - packet[2];

        if (packet[0] & 0xc0)
                psmouse_dbg(psmouse,
                            "overflow -- 0x%02x 0x%02x 0x%02x\n",
                            packet[0], packet[1], packet[2]);

        if (hgpk_discard_decay_hack(psmouse, x, y)) {
                if (tpdebug)
                        psmouse_dbg(psmouse, "discarding\n");
                return;
        }

        hgpk_spewing_hack(psmouse, left, right, x, y);

        if (tpdebug)
                psmouse_dbg(psmouse, "l=%d r=%d x=%d y=%d\n",
                            left, right, x, y);

        input_report_key(dev, BTN_LEFT, left);
        input_report_key(dev, BTN_RIGHT, right);

        input_report_rel(dev, REL_X, x);
        input_report_rel(dev, REL_Y, y);

        input_sync(dev);
}

static psmouse_ret_t hgpk_process_byte(struct psmouse *psmouse)
{
        struct hgpk_data *priv = psmouse->private;

        if (!hgpk_is_byte_valid(psmouse, psmouse->packet))
                return PSMOUSE_BAD_DATA;

        if (psmouse->pktcnt >= psmouse->pktsize) {
                if (priv->mode == HGPK_MODE_MOUSE)
                        hgpk_process_simple_packet(psmouse);
                else
                        hgpk_process_advanced_packet(psmouse);
                return PSMOUSE_FULL_PACKET;
        }

        if (priv->recalib_window) {
                if (time_before(jiffies, priv->recalib_window)) {
                        /*
                         * ugh, got a packet inside our recalibration
                         * window, schedule another recalibration.
                         */
                        psmouse_dbg(psmouse,
                                    "packet inside calibration window, queueing another recalibration\n");
                        psmouse_queue_work(psmouse, &priv->recalib_wq,
                                        msecs_to_jiffies(post_interrupt_delay));
                }
                priv->recalib_window = 0;
        }

        return PSMOUSE_GOOD_DATA;
}

static int hgpk_select_mode(struct psmouse *psmouse)
{
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        struct hgpk_data *priv = psmouse->private;
        int i;
        int cmd;

        /*
         * 4 disables to enable advanced mode
         * then 3 0xf2 bytes as the preamble for GS/PT selection
         */
        const int advanced_init[] = {
                PSMOUSE_CMD_DISABLE, PSMOUSE_CMD_DISABLE,
                PSMOUSE_CMD_DISABLE, PSMOUSE_CMD_DISABLE,
                0xf2, 0xf2, 0xf2,
        };

        switch (priv->mode) {
        case HGPK_MODE_MOUSE:
                psmouse->pktsize = 3;
                break;

        case HGPK_MODE_GLIDESENSOR:
        case HGPK_MODE_PENTABLET:
                psmouse->pktsize = 6;

                /* Switch to 'Advanced mode.', four disables in a row. */
                for (i = 0; i < ARRAY_SIZE(advanced_init); i++)
                        if (ps2_command(ps2dev, NULL, advanced_init[i]))
                                return -EIO;

                /* select between GlideSensor (mouse) or PenTablet */
                cmd = priv->mode == HGPK_MODE_GLIDESENSOR ?
                        PSMOUSE_CMD_SETSCALE11 : PSMOUSE_CMD_SETSCALE21;

                if (ps2_command(ps2dev, NULL, cmd))
                        return -EIO;
                break;

        default:
                return -EINVAL;
        }

        return 0;
}

static void hgpk_setup_input_device(struct input_dev *input,
                                    struct input_dev *old_input,
                                    enum hgpk_mode mode)
{
        if (old_input) {
                input->name = old_input->name;
                input->phys = old_input->phys;
                input->id = old_input->id;
                input->dev.parent = old_input->dev.parent;
        }

        memset(input->evbit, 0, sizeof(input->evbit));
        memset(input->relbit, 0, sizeof(input->relbit));
        memset(input->keybit, 0, sizeof(input->keybit));

        /* All modes report left and right buttons */
        __set_bit(EV_KEY, input->evbit);
        __set_bit(BTN_LEFT, input->keybit);
        __set_bit(BTN_RIGHT, input->keybit);

        switch (mode) {
        case HGPK_MODE_MOUSE:
                __set_bit(EV_REL, input->evbit);
                __set_bit(REL_X, input->relbit);
                __set_bit(REL_Y, input->relbit);
                break;

        case HGPK_MODE_GLIDESENSOR:
                __set_bit(BTN_TOUCH, input->keybit);
                __set_bit(BTN_TOOL_FINGER, input->keybit);

                __set_bit(EV_ABS, input->evbit);

                /* GlideSensor has pressure sensor, PenTablet does not */
                input_set_abs_params(input, ABS_PRESSURE, 0, 15, 0, 0);

                /* From device specs */
                input_set_abs_params(input, ABS_X, 0, 399, 0, 0);
                input_set_abs_params(input, ABS_Y, 0, 290, 0, 0);

                /* Calculated by hand based on usable size (52mm x 38mm) */
                input_abs_set_res(input, ABS_X, 8);
                input_abs_set_res(input, ABS_Y, 8);
                break;

        case HGPK_MODE_PENTABLET:
                __set_bit(BTN_TOUCH, input->keybit);
                __set_bit(BTN_TOOL_FINGER, input->keybit);

                __set_bit(EV_ABS, input->evbit);

                /* From device specs */
                input_set_abs_params(input, ABS_X, 0, 999, 0, 0);
                input_set_abs_params(input, ABS_Y, 5, 239, 0, 0);

                /* Calculated by hand based on usable size (156mm x 38mm) */
                input_abs_set_res(input, ABS_X, 6);
                input_abs_set_res(input, ABS_Y, 8);
                break;

        default:
                BUG();
        }
}

static int hgpk_reset_device(struct psmouse *psmouse, bool recalibrate)
{
        int err;

        psmouse_reset(psmouse);

        if (recalibrate) {
                struct ps2dev *ps2dev = &psmouse->ps2dev;

                /* send the recalibrate request */
                if (ps2_command(ps2dev, NULL, 0xf5) ||
                    ps2_command(ps2dev, NULL, 0xf5) ||
                    ps2_command(ps2dev, NULL, 0xe6) ||
                    ps2_command(ps2dev, NULL, 0xf5)) {
                        return -1;
                }

                /* according to ALPS, 150mS is required for recalibration */
                msleep(150);
        }

        err = hgpk_select_mode(psmouse);
        if (err) {
                psmouse_err(psmouse, "failed to select mode\n");
                return err;
        }

        hgpk_reset_hack_state(psmouse);

        return 0;
}

static int hgpk_force_recalibrate(struct psmouse *psmouse)
{
        struct hgpk_data *priv = psmouse->private;
        int err;

        /* C-series touchpads added the recalibrate command */
        if (psmouse->model < HGPK_MODEL_C)
                return 0;

        if (!autorecal) {
                psmouse_dbg(psmouse, "recalibration disabled, ignoring\n");
                return 0;
        }

        psmouse_dbg(psmouse, "recalibrating touchpad..\n");

        /* we don't want to race with the irq handler, nor with resyncs */
        psmouse_set_state(psmouse, PSMOUSE_INITIALIZING);

        /* start by resetting the device */
        err = hgpk_reset_device(psmouse, true);
        if (err)
                return err;

        /*
         * XXX: If a finger is down during this delay, recalibration will
         * detect capacitance incorrectly.  This is a hardware bug, and
         * we don't have a good way to deal with it.  The 2s window stuff
         * (below) is our best option for now.
         */
        if (psmouse_activate(psmouse))
                return -1;

        if (tpdebug)
                psmouse_dbg(psmouse, "touchpad reactivated\n");

        /*
         * If we get packets right away after recalibrating, it's likely
         * that a finger was on the touchpad.  If so, it's probably
         * miscalibrated, so we optionally schedule another.
         */
        if (recal_guard_time)
                priv->recalib_window = jiffies +
                        msecs_to_jiffies(recal_guard_time);

        return 0;
}

/*
 * This puts the touchpad in a power saving mode; according to ALPS, current
 * consumption goes down to 50uA after running this.  To turn power back on,
 * we drive MS-DAT low.  Measuring with a 1mA resolution ammeter says that
 * the current on the SUS_3.3V rail drops from 3mA or 4mA to 0 when we do this.
 *
 * We have no formal spec that details this operation -- the low-power
 * sequence came from a long-lost email trail.
 */
static int hgpk_toggle_powersave(struct psmouse *psmouse, int enable)
{
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        int timeo;
        int err;

        /* Added on D-series touchpads */
        if (psmouse->model < HGPK_MODEL_D)
                return 0;

        if (enable) {
                psmouse_set_state(psmouse, PSMOUSE_INITIALIZING);

                /*
                 * Sending a byte will drive MS-DAT low; this will wake up
                 * the controller.  Once we get an ACK back from it, it
                 * means we can continue with the touchpad re-init.  ALPS
                 * tells us that 1s should be long enough, so set that as
                 * the upper bound. (in practice, it takes about 3 loops.)
                 */
                for (timeo = 20; timeo > 0; timeo--) {
                        if (!ps2_sendbyte(ps2dev, PSMOUSE_CMD_DISABLE, 20))
                                break;
                        msleep(25);
                }

                err = hgpk_reset_device(psmouse, false);
                if (err) {
                        psmouse_err(psmouse, "Failed to reset device!\n");
                        return err;
                }

                /* should be all set, enable the touchpad */
                psmouse_activate(psmouse);
                psmouse_dbg(psmouse, "Touchpad powered up.\n");
        } else {
                psmouse_dbg(psmouse, "Powering off touchpad.\n");

                if (ps2_command(ps2dev, NULL, 0xec) ||
                    ps2_command(ps2dev, NULL, 0xec) ||
                    ps2_command(ps2dev, NULL, 0xea)) {
                        return -1;
                }

                psmouse_set_state(psmouse, PSMOUSE_IGNORE);

                /* probably won't see an ACK, the touchpad will be off */
                ps2_sendbyte(ps2dev, 0xec, 20);
        }

        return 0;
}

static int hgpk_poll(struct psmouse *psmouse)
{
        /* We can't poll, so always return failure. */
        return -1;
}

static int hgpk_reconnect(struct psmouse *psmouse)
{
        struct hgpk_data *priv = psmouse->private;

        /*
         * During suspend/resume the ps2 rails remain powered.  We don't want
         * to do a reset because it's flush data out of buffers; however,
         * earlier prototypes (B1) had some brokenness that required a reset.
         */
        if (olpc_board_at_least(olpc_board(0xb2)))
                if (psmouse->ps2dev.serio->dev.power.power_state.event !=
                                PM_EVENT_ON)
                        return 0;

        priv->powered = 1;
        return hgpk_reset_device(psmouse, false);
}

static ssize_t hgpk_show_powered(struct psmouse *psmouse, void *data, char *buf)
{
        struct hgpk_data *priv = psmouse->private;

        return sprintf(buf, "%d\n", priv->powered);
}

static ssize_t hgpk_set_powered(struct psmouse *psmouse, void *data,
                                const char *buf, size_t count)
{
        struct hgpk_data *priv = psmouse->private;
        unsigned int value;
        int err;

        err = kstrtouint(buf, 10, &value);
        if (err)
                return err;

        if (value > 1)
                return -EINVAL;

        if (value != priv->powered) {
                /*
                 * hgpk_toggle_power will deal w/ state so
                 * we're not racing w/ irq
                 */
                err = hgpk_toggle_powersave(psmouse, value);
                if (!err)
                        priv->powered = value;
        }

        return err ? err : count;
}

__PSMOUSE_DEFINE_ATTR(powered, S_IWUSR | S_IRUGO, NULL,
                      hgpk_show_powered, hgpk_set_powered, false);

static ssize_t attr_show_mode(struct psmouse *psmouse, void *data, char *buf)
{
        struct hgpk_data *priv = psmouse->private;

        return sprintf(buf, "%s\n", hgpk_mode_names[priv->mode]);
}

static ssize_t attr_set_mode(struct psmouse *psmouse, void *data,
                             const char *buf, size_t len)
{
        struct hgpk_data *priv = psmouse->private;
        enum hgpk_mode old_mode = priv->mode;
        enum hgpk_mode new_mode = hgpk_mode_from_name(buf, len);
        struct input_dev *old_dev = psmouse->dev;
        struct input_dev *new_dev;
        int err;

        if (new_mode == HGPK_MODE_INVALID)
                return -EINVAL;

        if (old_mode == new_mode)
                return len;

        new_dev = input_allocate_device();
        if (!new_dev)
                return -ENOMEM;

        psmouse_set_state(psmouse, PSMOUSE_INITIALIZING);

        /* Switch device into the new mode */
        priv->mode = new_mode;
        err = hgpk_reset_device(psmouse, false);
        if (err)
                goto err_try_restore;

        hgpk_setup_input_device(new_dev, old_dev, new_mode);

        psmouse_set_state(psmouse, PSMOUSE_CMD_MODE);

        err = input_register_device(new_dev);
        if (err)
                goto err_try_restore;

        psmouse->dev = new_dev;
        input_unregister_device(old_dev);

        return len;

err_try_restore:
        input_free_device(new_dev);
        priv->mode = old_mode;
        hgpk_reset_device(psmouse, false);

        return err;
}

PSMOUSE_DEFINE_ATTR(hgpk_mode, S_IWUSR | S_IRUGO, NULL,
                    attr_show_mode, attr_set_mode);

static ssize_t hgpk_trigger_recal_show(struct psmouse *psmouse,
                void *data, char *buf)
{
        return -EINVAL;
}

static ssize_t hgpk_trigger_recal(struct psmouse *psmouse, void *data,
                                const char *buf, size_t count)
{
        struct hgpk_data *priv = psmouse->private;
        unsigned int value;
        int err;

        err = kstrtouint(buf, 10, &value);
        if (err)
                return err;

        if (value != 1)
                return -EINVAL;

        /*
         * We queue work instead of doing recalibration right here
         * to avoid adding locking to to hgpk_force_recalibrate()
         * since workqueue provides serialization.
         */
        psmouse_queue_work(psmouse, &priv->recalib_wq, 0);
        return count;
}

__PSMOUSE_DEFINE_ATTR(recalibrate, S_IWUSR | S_IRUGO, NULL,
                      hgpk_trigger_recal_show, hgpk_trigger_recal, false);

static void hgpk_disconnect(struct psmouse *psmouse)
{
        struct hgpk_data *priv = psmouse->private;

        device_remove_file(&psmouse->ps2dev.serio->dev,
                           &psmouse_attr_powered.dattr);
        device_remove_file(&psmouse->ps2dev.serio->dev,
                           &psmouse_attr_hgpk_mode.dattr);

        if (psmouse->model >= HGPK_MODEL_C)
                device_remove_file(&psmouse->ps2dev.serio->dev,
                                   &psmouse_attr_recalibrate.dattr);

        psmouse_reset(psmouse);
        kfree(priv);
}

static void hgpk_recalib_work(struct work_struct *work)
{
        struct delayed_work *w = to_delayed_work(work);
        struct hgpk_data *priv = container_of(w, struct hgpk_data, recalib_wq);
        struct psmouse *psmouse = priv->psmouse;

        if (hgpk_force_recalibrate(psmouse))
                psmouse_err(psmouse, "recalibration failed!\n");
}

static int hgpk_register(struct psmouse *psmouse)
{
        struct hgpk_data *priv = psmouse->private;
        int err;

        /* register handlers */
        psmouse->protocol_handler = hgpk_process_byte;
        psmouse->poll = hgpk_poll;
        psmouse->disconnect = hgpk_disconnect;
        psmouse->reconnect = hgpk_reconnect;

        /* Disable the idle resync. */
        psmouse->resync_time = 0;
        /* Reset after a lot of bad bytes. */
        psmouse->resetafter = 1024;

        hgpk_setup_input_device(psmouse->dev, NULL, priv->mode);

        err = device_create_file(&psmouse->ps2dev.serio->dev,
                                 &psmouse_attr_powered.dattr);
        if (err) {
                psmouse_err(psmouse, "Failed creating 'powered' sysfs node\n");
                return err;
        }

        err = device_create_file(&psmouse->ps2dev.serio->dev,
                                 &psmouse_attr_hgpk_mode.dattr);
        if (err) {
                psmouse_err(psmouse,
                            "Failed creating 'hgpk_mode' sysfs node\n");
                goto err_remove_powered;
        }

        /* C-series touchpads added the recalibrate command */
        if (psmouse->model >= HGPK_MODEL_C) {
                err = device_create_file(&psmouse->ps2dev.serio->dev,
                                         &psmouse_attr_recalibrate.dattr);
                if (err) {
                        psmouse_err(psmouse,
                                    "Failed creating 'recalibrate' sysfs node\n");
                        goto err_remove_mode;
                }
        }

        return 0;

err_remove_mode:
        device_remove_file(&psmouse->ps2dev.serio->dev,
                           &psmouse_attr_hgpk_mode.dattr);
err_remove_powered:
        device_remove_file(&psmouse->ps2dev.serio->dev,
                           &psmouse_attr_powered.dattr);
        return err;
}

int hgpk_init(struct psmouse *psmouse)
{
        struct hgpk_data *priv;
        int err;

        priv = kzalloc(sizeof(struct hgpk_data), GFP_KERNEL);
        if (!priv) {
                err = -ENOMEM;
                goto alloc_fail;
        }

        psmouse->private = priv;

        priv->psmouse = psmouse;
        priv->powered = true;
        priv->mode = hgpk_default_mode;
        INIT_DELAYED_WORK(&priv->recalib_wq, hgpk_recalib_work);

        err = hgpk_reset_device(psmouse, false);

        if (err)
                goto init_fail;

        err = hgpk_register(psmouse);
        if (err)
                goto init_fail;

        return 0;

init_fail:
        kfree(priv);
alloc_fail:
        return err;
}

static enum hgpk_model_t hgpk_get_model(struct psmouse *psmouse)
{
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        unsigned char param[3];

        /* E7, E7, E7, E9 gets us a 3 byte identifier */
        if (ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE21) ||
            ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE21) ||
            ps2_command(ps2dev,  NULL, PSMOUSE_CMD_SETSCALE21) ||
            ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO)) {
                return -EIO;
        }

        psmouse_dbg(psmouse, "ID: %*ph\n", 3, param);

        /* HGPK signature: 0x67, 0x00, 0x<model> */
        if (param[0] != 0x67 || param[1] != 0x00)
                return -ENODEV;

        psmouse_info(psmouse, "OLPC touchpad revision 0x%x\n", param[2]);

        return param[2];
}

int hgpk_detect(struct psmouse *psmouse, bool set_properties)
{
        int version;

        version = hgpk_get_model(psmouse);
        if (version < 0)
                return version;

        if (set_properties) {
                psmouse->vendor = "ALPS";
                psmouse->name = "HGPK";
                psmouse->model = version;
        }

        return 0;
}

void hgpk_module_init(void)
{
        hgpk_default_mode = hgpk_mode_from_name(hgpk_mode_name,
                                                strlen(hgpk_mode_name));
        if (hgpk_default_mode == HGPK_MODE_INVALID) {
                hgpk_default_mode = HGPK_MODE_MOUSE;
                strlcpy(hgpk_mode_name, hgpk_mode_names[HGPK_MODE_MOUSE],
                        sizeof(hgpk_mode_name));
        }
}