/*
 * 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/input.h>
#include <linux/serio.h>
#include <linux/libps2.h>
#include <linux/delay.h>
#include <asm/olpc.h>

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

static int tpdebug;
module_param(tpdebug, int, 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 cause a recalibration.");

static int jumpy_delay = 1000;
module_param(jumpy_delay, int, 0644);
MODULE_PARM_DESC(jumpy_delay,
        "delay (ms) before recal after jumpiness detected");

static int spew_delay = 1000;
module_param(spew_delay, int, 0644);
MODULE_PARM_DESC(spew_delay,
        "delay (ms) before recal after packet spew detected");

static int recal_guard_time = 2000;
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 = 1000;
module_param(post_interrupt_delay, int, 0644);
MODULE_PARM_DESC(post_interrupt_delay,
        "delay (ms) before recal after recal interrupt detected");

static int autorecal = 1;
module_param(autorecal, int, 0644);
MODULE_PARM_DESC(autorecal, "enable recalibration in the driver");

/*
 * When the touchpad gets ultra-sensitive, one can keep their finger 1/2"
 * above the pad and still have it send packets.  This causes a jump cursor
 * when one places their finger on the pad.  We can probably detect the
 * jump as we see a large deltas (>= 100px).  In mouse mode, I've been
 * unable to even come close to 100px deltas during normal usage, so I think
 * this threshold is safe.  If a large delta occurs, trigger a recalibration.
 */
static void hgpk_jumpy_hack(struct psmouse *psmouse, int x, int y)
{
        struct hgpk_data *priv = psmouse->private;

        if (abs(x) > recalib_delta || abs(y) > recalib_delta) {
                hgpk_err(psmouse, ">%dpx jump detected (%d,%d)\n",
                                recalib_delta, x, y);
                /* My car gets forty rods to the hogshead and that's the
                 * way I likes it! */
                psmouse_queue_work(psmouse, &priv->recalib_wq,
                                msecs_to_jiffies(jumpy_delay));
        }
}

/*
 * 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;

        priv->x_tally += x;
        priv->y_tally += y;

        if (++priv->count > 100) {
                if (abs(priv->x_tally) < 3 && abs(priv->y_tally) < 3) {
                        hgpk_dbg(psmouse, "packet spew detected (%d,%d)\n",
                                 priv->x_tally, priv->y_tally);
                        psmouse_queue_work(psmouse, &priv->recalib_wq,
                                           msecs_to_jiffies(spew_delay));
                }
                /* reset every 100 packets */
                priv->count = 0;
                priv->x_tally = 0;
                priv->y_tally = 0;
        }
}

/*
 * 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
 */
static int hgpk_validate_byte(unsigned char *packet)
{
        return (packet[0] & 0x0C) != 0x08;
}

static void hgpk_process_packet(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        unsigned char *packet = psmouse->packet;
        int x, y, left, right;

        left = packet[0] & 1;
        right = (packet[0] >> 1) & 1;

        x = packet[1] - ((packet[0] << 4) & 0x100);
        y = ((packet[0] << 3) & 0x100) - packet[2];

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

        if (tpdebug)
                hgpk_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_validate_byte(psmouse->packet)) {
                hgpk_dbg(psmouse, "%s: (%d) %02x %02x %02x\n",
                                __func__, psmouse->pktcnt, psmouse->packet[0],
                                psmouse->packet[1], psmouse->packet[2]);
                return PSMOUSE_BAD_DATA;
        }

        if (psmouse->pktcnt >= psmouse->pktsize) {
                hgpk_process_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.
                         */
                        hgpk_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_force_recalibrate(struct psmouse *psmouse)
{
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        struct hgpk_data *priv = psmouse->private;

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

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

        /* start by resetting the device */
        psmouse_reset(psmouse);

        /* 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);

        /* 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 (ps2_command(ps2dev, NULL, PSMOUSE_CMD_ENABLE))
                return -1;

        psmouse_set_state(psmouse, PSMOUSE_ACTIVATED);

        /* After we recalibrate, we shouldn't get any packets for 2s.  If
         * we do, it's likely that someone's finger was on the touchpad.
         * If someone's finger *was* on the touchpad, it's probably
         * miscalibrated.  So, we should schedule another recalibration
         */
        priv->recalib_window = jiffies +  msecs_to_jiffies(recal_guard_time);

        return 0;
}

/*
 * This kills power to the touchpad; according to ALPS, current consumption
 * goes down to 50uA after running this.  To turn power back on, we drive
 * MS-DAT low.
 */
static int hgpk_toggle_power(struct psmouse *psmouse, int enable)
{
        struct ps2dev *ps2dev = &psmouse->ps2dev;
        int timeo;

        /* 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.
                 */
                for (timeo = 20; timeo > 0; timeo--) {
                        if (!ps2_sendbyte(&psmouse->ps2dev,
                                        PSMOUSE_CMD_DISABLE, 20))
                                break;
                        msleep(50);
                }

                psmouse_reset(psmouse);

                /* should be all set, enable the touchpad */
                ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_ENABLE);
                psmouse_set_state(psmouse, PSMOUSE_ACTIVATED);

        } else {
                hgpk_dbg(psmouse, "Powering off touchpad.\n");
                psmouse_set_state(psmouse, PSMOUSE_IGNORE);

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

                /* probably won't see an ACK, the touchpad will be off */
                ps2_sendbyte(&psmouse->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)
{
        /* 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;

        psmouse_reset(psmouse);

        return 0;
}

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 long value;
        int err;

        err = strict_strtoul(buf, 10, &value);
        if (err || 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_power(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 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 long value;
        int err;

        err = strict_strtoul(buf, 10, &value);
        if (err || 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);

        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;

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

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

static int hgpk_register(struct psmouse *psmouse)
{
        struct input_dev *dev = psmouse->dev;
        int err;

        /* unset the things that psmouse-base sets which we don't have */
        __clear_bit(BTN_MIDDLE, dev->keybit);

        /* set the things we do have */
        __set_bit(EV_KEY, dev->evbit);
        __set_bit(EV_REL, dev->evbit);

        __set_bit(REL_X, dev->relbit);
        __set_bit(REL_Y, dev->relbit);

        __set_bit(BTN_LEFT, dev->keybit);
        __set_bit(BTN_RIGHT, dev->keybit);

        /* register handlers */
        psmouse->protocol_handler = hgpk_process_byte;
        psmouse->poll = hgpk_poll;
        psmouse->disconnect = hgpk_disconnect;
        psmouse->reconnect = hgpk_reconnect;
        psmouse->pktsize = 3;

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

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

        /* 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) {
                        hgpk_err(psmouse,
                                "Failed creating 'recalibrate' sysfs node\n");
                        device_remove_file(&psmouse->ps2dev.serio->dev,
                                        &psmouse_attr_powered.dattr);
                        return err;
                }
        }

        return 0;
}

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

        priv = kzalloc(sizeof(struct hgpk_data), GFP_KERNEL);
        if (!priv)
                goto alloc_fail;

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

        err = psmouse_reset(psmouse);
        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;
        }

        hgpk_dbg(psmouse, "ID: %02x %02x %02x\n", param[0], param[1], param[2]);

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

        hgpk_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;
}