/*
 * 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/slab.h>
#include <linux/input.h>
#include <linux/input/sparse-keymap.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>

#include <linux/i2c/dm355evm_msp.h>
#include <linux/module.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;
};

/* These initial keycodes can be remapped */
static const struct key_entry 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.)
         */
        { KE_KEY, 0x00d8, { KEY_OK } },         /* SW12 */
        { KE_KEY, 0x00b8, { KEY_UP } },         /* SW13 */
        { KE_KEY, 0x00e8, { KEY_DOWN } },       /* SW11 */
        { KE_KEY, 0x0078, { KEY_LEFT } },       /* SW14 */
        { KE_KEY, 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).
         */
        { KE_KEY, 0x300c, { KEY_POWER } },      /* NOTE: docs omit this */
        { KE_KEY, 0x3000, { KEY_NUMERIC_0 } },
        { KE_KEY, 0x3001, { KEY_NUMERIC_1 } },
        { KE_KEY, 0x3002, { KEY_NUMERIC_2 } },
        { KE_KEY, 0x3003, { KEY_NUMERIC_3 } },
        { KE_KEY, 0x3004, { KEY_NUMERIC_4 } },
        { KE_KEY, 0x3005, { KEY_NUMERIC_5 } },
        { KE_KEY, 0x3006, { KEY_NUMERIC_6 } },
        { KE_KEY, 0x3007, { KEY_NUMERIC_7 } },
        { KE_KEY, 0x3008, { KEY_NUMERIC_8 } },
        { KE_KEY, 0x3009, { KEY_NUMERIC_9 } },
        { KE_KEY, 0x3022, { KEY_ENTER } },
        { KE_KEY, 0x30ec, { KEY_MODE } },       /* "tv/vcr/..." */
        { KE_KEY, 0x300f, { KEY_SELECT } },     /* "info" */
        { KE_KEY, 0x3020, { KEY_CHANNELUP } },  /* "up" */
        { KE_KEY, 0x302e, { KEY_MENU } },       /* "in/out" */
        { KE_KEY, 0x3011, { KEY_VOLUMEDOWN } }, /* "left" */
        { KE_KEY, 0x300d, { KEY_MUTE } },       /* "ok" */
        { KE_KEY, 0x3010, { KEY_VOLUMEUP } },   /* "right" */
        { KE_KEY, 0x301e, { KEY_SUBTITLE } },   /* "cc" */
        { KE_KEY, 0x3021, { KEY_CHANNELDOWN } },/* "down" */
        { KE_KEY, 0x3022, { KEY_PREVIOUS } },
        { KE_KEY, 0x3026, { KEY_SLEEP } },
        { KE_KEY, 0x3172, { KEY_REWIND } },     /* NOTE: docs wrongly say 0x30ca */
        { KE_KEY, 0x3175, { KEY_PLAY } },
        { KE_KEY, 0x3174, { KEY_FASTFORWARD } },
        { KE_KEY, 0x3177, { KEY_RECORD } },
        { KE_KEY, 0x3176, { KEY_STOP } },
        { KE_KEY, 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)
{
        static u16 last_event;
        struct dm355evm_keys *keys = _keys;
        const struct key_entry *ke;
        unsigned int keycode;
        int status;
        u16 event;

        /* For simplicity we ignore INPUT_COUNT and just read
         * events until we get the "queue empty" indicator.
         * Reading INPUT_LOW decrements the count.
         */
        for (;;) {
                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 report it as unknown */
                ke = sparse_keymap_entry_from_scancode(keys->input, event);
                keycode = ke ? ke->keycode : KEY_UNKNOWN;
                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_keys_probe(struct platform_device *pdev)
{
        struct dm355evm_keys    *keys;
        struct input_dev        *input;
        int                     irq;
        int                     error;

        keys = devm_kzalloc(&pdev->dev, sizeof (*keys), GFP_KERNEL);
        if (!keys)
                return -ENOMEM;

        input = devm_input_allocate_device(&pdev->dev);
        if (!input)
                return -ENOMEM;

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

        input->name = "DM355 EVM Controls";
        input->phys = "dm355evm/input0";

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

        error = sparse_keymap_setup(input, dm355evm_keys, NULL);
        if (error)
                return error;

        /* REVISIT:  flush the event queue? */

        /* set up "threaded IRQ handler" */
        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        error = devm_request_threaded_irq(&pdev->dev, irq,
                                          NULL, dm355evm_keys_irq,
                                          IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                                          dev_name(&pdev->dev), keys);
        if (error)
                return error;

        /* register */
        error = input_register_device(input);
        if (error)
                return error;

        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,
        .driver         = {
                .name   = "dm355evm_keys",
        },
};
module_platform_driver(dm355evm_keys_driver);

MODULE_LICENSE("GPL");