/*
 * dm355evm_keys.c - support buttons and IR remote on DM355 EVM board
 *
 * Copyright (c) 2008 by David Brownell
 *
 * 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.
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>

#include <linux/i2c/dm355evm_msp.h>


/*
 * The MSP430 firmware on the DM355 EVM monitors on-board pushbuttons
 * and an IR receptor used for the remote control.  When any key is
 * pressed, or its autorepeat kicks in, an event is sent.  This driver
 * read those events from the small (32 event) queue and reports them.
 *
 * Note that physically there can only be one of these devices.
 *
 * This driver was tested with firmware revision A4.
 */
struct dm355evm_keys {
        struct input_dev        *input;
        struct device           *dev;
        int                     irq;
};

/* These initial keycodes can be remapped by dm355evm_setkeycode(). */
static struct {
        u16     event;
        u16     keycode;
} dm355evm_keys[] = {

        /*
         * Pushbuttons on the EVM board ... note that the labels for these
         * are SW10/SW11/etc on the PC board.  The left/right orientation
         * comes only from the firmware's documentation, and presumes the
         * power connector is immediately in front of you and the IR sensor
         * is to the right.  (That is, rotate the board counter-clockwise
         * by 90 degrees from the SW10/etc and "DM355 EVM" labels.)
         */
        { 0x00d8, KEY_OK, },            /* SW12 */
        { 0x00b8, KEY_UP, },            /* SW13 */
        { 0x00e8, KEY_DOWN, },          /* SW11 */
        { 0x0078, KEY_LEFT, },          /* SW14 */
        { 0x00f0, KEY_RIGHT, },         /* SW10 */

        /*
         * IR buttons ... codes assigned to match the universal remote
         * provided with the EVM (Philips PM4S) using DVD code 0020.
         *
         * These event codes match firmware documentation, but other
         * remote controls could easily send more RC5-encoded events.
         * The PM4S manual was used in several cases to help select
         * a keycode reflecting the intended usage.
         *
         * RC5 codes are 14 bits, with two start bits (0x3 prefix)
         * and a toggle bit (masked out below).
         */
        { 0x300c, KEY_POWER, },         /* NOTE: docs omit this */
        { 0x3000, KEY_NUMERIC_0, },
        { 0x3001, KEY_NUMERIC_1, },
        { 0x3002, KEY_NUMERIC_2, },
        { 0x3003, KEY_NUMERIC_3, },
        { 0x3004, KEY_NUMERIC_4, },
        { 0x3005, KEY_NUMERIC_5, },
        { 0x3006, KEY_NUMERIC_6, },
        { 0x3007, KEY_NUMERIC_7, },
        { 0x3008, KEY_NUMERIC_8, },
        { 0x3009, KEY_NUMERIC_9, },
        { 0x3022, KEY_ENTER, },
        { 0x30ec, KEY_MODE, },          /* "tv/vcr/..." */
        { 0x300f, KEY_SELECT, },        /* "info" */
        { 0x3020, KEY_CHANNELUP, },     /* "up" */
        { 0x302e, KEY_MENU, },          /* "in/out" */
        { 0x3011, KEY_VOLUMEDOWN, },    /* "left" */
        { 0x300d, KEY_MUTE, },          /* "ok" */
        { 0x3010, KEY_VOLUMEUP, },      /* "right" */
        { 0x301e, KEY_SUBTITLE, },      /* "cc" */
        { 0x3021, KEY_CHANNELDOWN, },   /* "down" */
        { 0x3022, KEY_PREVIOUS, },
        { 0x3026, KEY_SLEEP, },
        { 0x3172, KEY_REWIND, },        /* NOTE: docs wrongly say 0x30ca */
        { 0x3175, KEY_PLAY, },
        { 0x3174, KEY_FASTFORWARD, },
        { 0x3177, KEY_RECORD, },
        { 0x3176, KEY_STOP, },
        { 0x3169, KEY_PAUSE, },
};

/*
 * Because we communicate with the MSP430 using I2C, and all I2C calls
 * in Linux sleep, we use a threaded IRQ handler.  The IRQ itself is
 * active low, but we go through the GPIO controller so we can trigger
 * on falling edges and not worry about enabling/disabling the IRQ in
 * the keypress handling path.
 */
static irqreturn_t dm355evm_keys_irq(int irq, void *_keys)
{
        struct dm355evm_keys    *keys = _keys;
        int                     status;

        /* For simplicity we ignore INPUT_COUNT and just read
         * events until we get the "queue empty" indicator.
         * Reading INPUT_LOW decrements the count.
         */
        for (;;) {
                static u16      last_event;
                u16             event;
                int             keycode;
                int             i;

                status = dm355evm_msp_read(DM355EVM_MSP_INPUT_HIGH);
                if (status < 0) {
                        dev_dbg(keys->dev, "input high err %d\n",
                                        status);
                        break;
                }
                event = status << 8;

                status = dm355evm_msp_read(DM355EVM_MSP_INPUT_LOW);
                if (status < 0) {
                        dev_dbg(keys->dev, "input low err %d\n",
                                        status);
                        break;
                }
                event |= status;
                if (event == 0xdead)
                        break;

                /* Press and release a button:  two events, same code.
                 * Press and hold (autorepeat), then release: N events
                 * (N > 2), same code.  For RC5 buttons the toggle bits
                 * distinguish (for example) "1-autorepeat" from "1 1";
                 * but PCB buttons don't support that bit.
                 *
                 * So we must synthesize release events.  We do that by
                 * mapping events to a press/release event pair; then
                 * to avoid adding extra events, skip the second event
                 * of each pair.
                 */
                if (event == last_event) {
                        last_event = 0;
                        continue;
                }
                last_event = event;

                /* ignore the RC5 toggle bit */
                event &= ~0x0800;

                /* find the key, or leave it as unknown */
                keycode = KEY_UNKNOWN;
                for (i = 0; i < ARRAY_SIZE(dm355evm_keys); i++) {
                        if (dm355evm_keys[i].event != event)
                                continue;
                        keycode = dm355evm_keys[i].keycode;
                        break;
                }
                dev_dbg(keys->dev,
                        "input event 0x%04x--> keycode %d\n",
                        event, keycode);

                /* report press + release */
                input_report_key(keys->input, keycode, 1);
                input_sync(keys->input);
                input_report_key(keys->input, keycode, 0);
                input_sync(keys->input);
        }
        return IRQ_HANDLED;
}

static int dm355evm_setkeycode(struct input_dev *dev, int index, int keycode)
{
        u16             old_keycode;
        unsigned        i;

        if (((unsigned)index) >= ARRAY_SIZE(dm355evm_keys))
                return -EINVAL;

        old_keycode = dm355evm_keys[index].keycode;
        dm355evm_keys[index].keycode = keycode;
        set_bit(keycode, dev->keybit);

        for (i = 0; i < ARRAY_SIZE(dm355evm_keys); i++) {
                if (dm355evm_keys[index].keycode == old_keycode)
                        goto done;
        }
        clear_bit(old_keycode, dev->keybit);
done:
        return 0;
}

static int dm355evm_getkeycode(struct input_dev *dev, int index, int *keycode)
{
        if (((unsigned)index) >= ARRAY_SIZE(dm355evm_keys))
                return -EINVAL;

        return dm355evm_keys[index].keycode;
}

/*----------------------------------------------------------------------*/

static int __devinit dm355evm_keys_probe(struct platform_device *pdev)
{
        struct dm355evm_keys    *keys;
        struct input_dev        *input;
        int                     status;
        int                     i;

        /* allocate instance struct and input dev */
        keys = kzalloc(sizeof *keys, GFP_KERNEL);
        input = input_allocate_device();
        if (!keys || !input) {
                status = -ENOMEM;
                goto fail1;
        }

        keys->dev = &pdev->dev;
        keys->input = input;

        /* set up "threaded IRQ handler" */
        status = platform_get_irq(pdev, 0);
        if (status < 0)
                goto fail1;
        keys->irq = status;

        input_set_drvdata(input, keys);

        input->name = "DM355 EVM Controls";
        input->phys = "dm355evm/input0";
        input->dev.parent = &pdev->dev;

        input->id.bustype = BUS_I2C;
        input->id.product = 0x0355;
        input->id.version = dm355evm_msp_read(DM355EVM_MSP_FIRMREV);

        input->evbit[0] = BIT(EV_KEY);
        for (i = 0; i < ARRAY_SIZE(dm355evm_keys); i++)
                __set_bit(dm355evm_keys[i].keycode, input->keybit);

        input->setkeycode = dm355evm_setkeycode;
        input->getkeycode = dm355evm_getkeycode;

        /* REVISIT:  flush the event queue? */

        status = request_threaded_irq(keys->irq, NULL, dm355evm_keys_irq,
                        IRQF_TRIGGER_FALLING, dev_name(&pdev->dev), keys);
        if (status < 0)
                goto fail1;

        /* register */
        status = input_register_device(input);
        if (status < 0)
                goto fail2;

        platform_set_drvdata(pdev, keys);

        return 0;

fail2:
        free_irq(keys->irq, keys);
fail1:
        input_free_device(input);
        kfree(keys);
        dev_err(&pdev->dev, "can't register, err %d\n", status);

        return status;
}

static int __devexit dm355evm_keys_remove(struct platform_device *pdev)
{
        struct dm355evm_keys    *keys = platform_get_drvdata(pdev);

        free_irq(keys->irq, keys);
        input_unregister_device(keys->input);
        kfree(keys);

        return 0;
}

/* REVISIT:  add suspend/resume when DaVinci supports it.  The IRQ should
 * be able to wake up the system.  When device_may_wakeup(&pdev->dev), call
 * enable_irq_wake() on suspend, and disable_irq_wake() on resume.
 */

/*
 * I2C is used to talk to the MSP430, but this platform device is
 * exposed by an MFD driver that manages I2C communications.
 */
static struct platform_driver dm355evm_keys_driver = {
        .probe          = dm355evm_keys_probe,
        .remove         = __devexit_p(dm355evm_keys_remove),
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = "dm355evm_keys",
        },
};

static int __init dm355evm_keys_init(void)
{
        return platform_driver_register(&dm355evm_keys_driver);
}
module_init(dm355evm_keys_init);

static void __exit dm355evm_keys_exit(void)
{
        platform_driver_unregister(&dm355evm_keys_driver);
}
module_exit(dm355evm_keys_exit);

MODULE_LICENSE("GPL");