/*
 * HID driver for Nintendo Wiimote extension devices
 * Copyright (c) 2011 David Herrmann
 */

/*
 * 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/atomic.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/workqueue.h>
#include "hid-wiimote.h"

struct wiimote_ext {
	struct wiimote_data *wdata;
	struct work_struct worker;
	struct input_dev *input;
	struct input_dev *mp_input;

	atomic_t opened;
	atomic_t mp_opened;
	bool plugged;
	bool motionp;
	__u8 ext_type;
};

enum wiiext_type {
	WIIEXT_NONE,		/* placeholder */
	WIIEXT_CLASSIC,		/* Nintendo classic controller */
	WIIEXT_NUNCHUCK,	/* Nintendo nunchuck controller */
};

/* diable all extensions */
static void ext_disable(struct wiimote_ext *ext)
{
	unsigned long flags;
	__u8 wmem = 0x55;

	if (!wiimote_cmd_acquire(ext->wdata)) {
		wiimote_cmd_write(ext->wdata, 0xa400f0, &wmem, sizeof(wmem));
		wiimote_cmd_release(ext->wdata);
	}

	spin_lock_irqsave(&ext->wdata->state.lock, flags);
	ext->motionp = false;
	ext->ext_type = WIIEXT_NONE;
	wiiproto_req_drm(ext->wdata, WIIPROTO_REQ_NULL);
	spin_unlock_irqrestore(&ext->wdata->state.lock, flags);
}

static bool motionp_read(struct wiimote_ext *ext)
{
	__u8 rmem[2], wmem;
	ssize_t ret;
	bool avail = false;

	if (!atomic_read(&ext->mp_opened))
		return false;

	if (wiimote_cmd_acquire(ext->wdata))
		return false;

	/* initialize motion plus */
	wmem = 0x55;
	ret = wiimote_cmd_write(ext->wdata, 0xa600f0, &wmem, sizeof(wmem));
	if (ret)
		goto error;

	/* read motion plus ID */
	ret = wiimote_cmd_read(ext->wdata, 0xa600fe, rmem, 2);
	if (ret == 2 || rmem[1] == 0x5)
		avail = true;

error:
	wiimote_cmd_release(ext->wdata);
	return avail;
}

static __u8 ext_read(struct wiimote_ext *ext)
{
	ssize_t ret;
	__u8 rmem[2], wmem;
	__u8 type = WIIEXT_NONE;

	if (!ext->plugged || !atomic_read(&ext->opened))
		return WIIEXT_NONE;

	if (wiimote_cmd_acquire(ext->wdata))
		return WIIEXT_NONE;

	/* initialize extension */
	wmem = 0x55;
	ret = wiimote_cmd_write(ext->wdata, 0xa400f0, &wmem, sizeof(wmem));
	if (!ret) {
		/* disable encryption */
		wmem = 0x0;
		wiimote_cmd_write(ext->wdata, 0xa400fb, &wmem, sizeof(wmem));
	}

	/* read extension ID */
	ret = wiimote_cmd_read(ext->wdata, 0xa400fe, rmem, 2);
	if (ret == 2) {
		if (rmem[0] == 0 && rmem[1] == 0)
			type = WIIEXT_NUNCHUCK;
		else if (rmem[0] == 0x01 && rmem[1] == 0x01)
			type = WIIEXT_CLASSIC;
	}

	wiimote_cmd_release(ext->wdata);

	return type;
}

static void ext_enable(struct wiimote_ext *ext, bool motionp, __u8 ext_type)
{
	unsigned long flags;
	__u8 wmem;
	int ret;

	if (motionp) {
		if (wiimote_cmd_acquire(ext->wdata))
			return;

		if (ext_type == WIIEXT_CLASSIC)
			wmem = 0x07;
		else if (ext_type == WIIEXT_NUNCHUCK)
			wmem = 0x05;
		else
			wmem = 0x04;

		ret = wiimote_cmd_write(ext->wdata, 0xa600fe, &wmem, sizeof(wmem));
		wiimote_cmd_release(ext->wdata);
		if (ret)
			return;
	}

	spin_lock_irqsave(&ext->wdata->state.lock, flags);
	ext->motionp = motionp;
	ext->ext_type = ext_type;
	wiiproto_req_drm(ext->wdata, WIIPROTO_REQ_NULL);
	spin_unlock_irqrestore(&ext->wdata->state.lock, flags);
}

static void wiiext_worker(struct work_struct *work)
{
	struct wiimote_ext *ext = container_of(work, struct wiimote_ext,
									worker);
	bool motionp;
	__u8 ext_type;

	ext_disable(ext);
	motionp = motionp_read(ext);
	ext_type = ext_read(ext);
	ext_enable(ext, motionp, ext_type);
}

/* schedule work only once, otherwise mark for reschedule */
static void wiiext_schedule(struct wiimote_ext *ext)
{
	queue_work(system_nrt_wq, &ext->worker);
}

/*
 * Reacts on extension port events
 * Whenever the driver gets an event from the wiimote that an extension has been
 * plugged or unplugged, this funtion shall be called. It checks what extensions
 * are connected and initializes and activates them.
 * This can be called in atomic context. The initialization is done in a
 * separate worker thread. The state.lock spinlock must be held by the caller.
 */
void wiiext_event(struct wiimote_data *wdata, bool plugged)
{
	if (!wdata->ext)
		return;

	if (wdata->ext->plugged == plugged)
		return;

	wdata->ext->plugged = plugged;
	/*
	 * We need to call wiiext_schedule(wdata->ext) here, however, the
	 * extension initialization logic is not fully understood and so
	 * automatic initialization is not supported, yet.
	 */
}

/*
 * Returns true if the current DRM mode should contain extension data and false
 * if there is no interest in extension data.
 * All supported extensions send 6 byte extension data so any DRM that contains
 * extension bytes is fine.
 * The caller must hold the state.lock spinlock.
 */
bool wiiext_active(struct wiimote_data *wdata)
{
	if (!wdata->ext)
		return false;

	return wdata->ext->motionp || wdata->ext->ext_type;
}

static void handler_motionp(struct wiimote_ext *ext, const __u8 *payload)
{
}

static void handler_nunchuck(struct wiimote_ext *ext, const __u8 *payload)
{
}

static void handler_classic(struct wiimote_ext *ext, const __u8 *payload)
{
}

/* call this with state.lock spinlock held */
void wiiext_handle(struct wiimote_data *wdata, const __u8 *payload)
{
	struct wiimote_ext *ext = wdata->ext;

	if (!ext)
		return;

	if (ext->motionp && (payload[5] & 0x02)) {
		handler_motionp(ext, payload);
	} else if (ext->ext_type == WIIEXT_NUNCHUCK) {
		handler_nunchuck(ext, payload);
	} else if (ext->ext_type == WIIEXT_CLASSIC) {
		handler_classic(ext, payload);
	}
}

static ssize_t wiiext_show(struct device *dev, struct device_attribute *attr,
								char *buf)
{
	struct wiimote_data *wdata = dev_to_wii(dev);
	__u8 type = WIIEXT_NONE;
	bool motionp = false;
	unsigned long flags;

	spin_lock_irqsave(&wdata->state.lock, flags);
	if (wdata->ext) {
		motionp = wdata->ext->motionp;
		type = wdata->ext->ext_type;
	}
	spin_unlock_irqrestore(&wdata->state.lock, flags);

	if (type == WIIEXT_NUNCHUCK) {
		if (motionp)
			return sprintf(buf, "motionp+nunchuck\n");
		else
			return sprintf(buf, "nunchuck\n");
	} else if (type == WIIEXT_CLASSIC) {
		if (motionp)
			return sprintf(buf, "motionp+classic\n");
		else
			return sprintf(buf, "classic\n");
	} else {
		if (motionp)
			return sprintf(buf, "motionp\n");
		else
			return sprintf(buf, "none\n");
	}
}

static DEVICE_ATTR(extension, S_IRUGO, wiiext_show, NULL);

static int wiiext_input_open(struct input_dev *dev)
{
	struct wiimote_ext *ext = input_get_drvdata(dev);
	int ret;

	ret = hid_hw_open(ext->wdata->hdev);
	if (ret)
		return ret;

	atomic_inc(&ext->opened);
	wiiext_schedule(ext);

	return 0;
}

static void wiiext_input_close(struct input_dev *dev)
{
	struct wiimote_ext *ext = input_get_drvdata(dev);

	atomic_dec(&ext->opened);
	wiiext_schedule(ext);
	hid_hw_close(ext->wdata->hdev);
}

static int wiiext_mp_open(struct input_dev *dev)
{
	struct wiimote_ext *ext = input_get_drvdata(dev);
	int ret;

	ret = hid_hw_open(ext->wdata->hdev);
	if (ret)
		return ret;

	atomic_inc(&ext->mp_opened);
	wiiext_schedule(ext);

	return 0;
}

static void wiiext_mp_close(struct input_dev *dev)
{
	struct wiimote_ext *ext = input_get_drvdata(dev);

	atomic_dec(&ext->mp_opened);
	wiiext_schedule(ext);
	hid_hw_close(ext->wdata->hdev);
}

/* Initializes the extension driver of a wiimote */
int wiiext_init(struct wiimote_data *wdata)
{
	struct wiimote_ext *ext;
	unsigned long flags;
	int ret;

	ext = kzalloc(sizeof(*ext), GFP_KERNEL);
	if (!ext)
		return -ENOMEM;

	ext->wdata = wdata;
	INIT_WORK(&ext->worker, wiiext_worker);

	ext->input = input_allocate_device();
	if (!ext->input) {
		ret = -ENOMEM;
		goto err_input;
	}

	input_set_drvdata(ext->input, ext);
	ext->input->open = wiiext_input_open;
	ext->input->close = wiiext_input_close;
	ext->input->dev.parent = &wdata->hdev->dev;
	ext->input->id.bustype = wdata->hdev->bus;
	ext->input->id.vendor = wdata->hdev->vendor;
	ext->input->id.product = wdata->hdev->product;
	ext->input->id.version = wdata->hdev->version;
	ext->input->name = WIIMOTE_NAME " Extension";

	ret = input_register_device(ext->input);
	if (ret) {
		input_free_device(ext->input);
		goto err_input;
	}

	ext->mp_input = input_allocate_device();
	if (!ext->mp_input) {
		ret = -ENOMEM;
		goto err_mp;
	}

	input_set_drvdata(ext->mp_input, ext);
	ext->mp_input->open = wiiext_mp_open;
	ext->mp_input->close = wiiext_mp_close;
	ext->mp_input->dev.parent = &wdata->hdev->dev;
	ext->mp_input->id.bustype = wdata->hdev->bus;
	ext->mp_input->id.vendor = wdata->hdev->vendor;
	ext->mp_input->id.product = wdata->hdev->product;
	ext->mp_input->id.version = wdata->hdev->version;
	ext->mp_input->name = WIIMOTE_NAME " Motion+";

	ret = input_register_device(ext->mp_input);
	if (ret) {
		input_free_device(ext->mp_input);
		goto err_mp;
	}

	ret = device_create_file(&wdata->hdev->dev, &dev_attr_extension);
	if (ret)
		goto err_dev;

	spin_lock_irqsave(&wdata->state.lock, flags);
	wdata->ext = ext;
	spin_unlock_irqrestore(&wdata->state.lock, flags);

	return 0;

err_dev:
	input_unregister_device(ext->mp_input);
err_mp:
	input_unregister_device(ext->input);
err_input:
	kfree(ext);
	return ret;
}

/* Deinitializes the extension driver of a wiimote */
void wiiext_deinit(struct wiimote_data *wdata)
{
	struct wiimote_ext *ext = wdata->ext;
	unsigned long flags;

	if (!ext)
		return;

	/*
	 * We first unset wdata->ext to avoid further input from the wiimote
	 * core. The worker thread does not access this pointer so it is not
	 * affected by this.
	 * We kill the worker after this so it does not get respawned during
	 * deinitialization.
	 */

	spin_lock_irqsave(&wdata->state.lock, flags);
	wdata->ext = NULL;
	spin_unlock_irqrestore(&wdata->state.lock, flags);

	device_remove_file(&wdata->hdev->dev, &dev_attr_extension);
	input_unregister_device(ext->mp_input);
	input_unregister_device(ext->input);

	cancel_work_sync(&ext->worker);
	kfree(ext);
}