/*
 * 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/mfd/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");
