/* rc-ir-raw.c - handle IR pulse/space events
 *
 * Copyright (C) 2010 by Mauro Carvalho Chehab
 *
 * 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 version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 */

#include <linux/export.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/kmod.h>
#include <linux/sched.h>
#include <linux/freezer.h>
#include "rc-core-priv.h"

/* Used to keep track of IR raw clients, protected by ir_raw_handler_lock */
static LIST_HEAD(ir_raw_client_list);

/* Used to handle IR raw handler extensions */
static DEFINE_MUTEX(ir_raw_handler_lock);
static LIST_HEAD(ir_raw_handler_list);
static DEFINE_MUTEX(available_protocols_lock);
static u64 available_protocols;

static int ir_raw_event_thread(void *data)
{
        struct ir_raw_event ev;
        struct ir_raw_handler *handler;
        struct ir_raw_event_ctrl *raw = (struct ir_raw_event_ctrl *)data;

        while (!kthread_should_stop()) {

                spin_lock_irq(&raw->lock);

                if (!kfifo_len(&raw->kfifo)) {
                        set_current_state(TASK_INTERRUPTIBLE);

                        if (kthread_should_stop())
                                set_current_state(TASK_RUNNING);

                        spin_unlock_irq(&raw->lock);
                        schedule();
                        continue;
                }

                if(!kfifo_out(&raw->kfifo, &ev, 1))
                        dev_err(&raw->dev->dev, "IR event FIFO is empty!\n");
                spin_unlock_irq(&raw->lock);

                mutex_lock(&ir_raw_handler_lock);
                list_for_each_entry(handler, &ir_raw_handler_list, list)
                        if (raw->dev->enabled_protocols & handler->protocols ||
                            !handler->protocols)
                                handler->decode(raw->dev, ev);
                raw->prev_ev = ev;
                mutex_unlock(&ir_raw_handler_lock);
        }

        return 0;
}

/**
 * ir_raw_event_store() - pass a pulse/space duration to the raw ir decoders
 * @dev:        the struct rc_dev device descriptor
 * @ev:         the struct ir_raw_event descriptor of the pulse/space
 *
 * This routine (which may be called from an interrupt context) stores a
 * pulse/space duration for the raw ir decoding state machines. Pulses are
 * signalled as positive values and spaces as negative values. A zero value
 * will reset the decoding state machines.
 */
int ir_raw_event_store(struct rc_dev *dev, struct ir_raw_event *ev)
{
        if (!dev->raw)
                return -EINVAL;

        IR_dprintk(2, "sample: (%05dus %s)\n",
                   TO_US(ev->duration), TO_STR(ev->pulse));

        if (!kfifo_put(&dev->raw->kfifo, *ev)) {
                dev_err(&dev->dev, "IR event FIFO is full!\n");
                return -ENOSPC;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(ir_raw_event_store);

/**
 * ir_raw_event_store_edge() - notify raw ir decoders of the start of a pulse/space
 * @dev:        the struct rc_dev device descriptor
 * @type:       the type of the event that has occurred
 *
 * This routine (which may be called from an interrupt context) is used to
 * store the beginning of an ir pulse or space (or the start/end of ir
 * reception) for the raw ir decoding state machines. This is used by
 * hardware which does not provide durations directly but only interrupts
 * (or similar events) on state change.
 */
int ir_raw_event_store_edge(struct rc_dev *dev, enum raw_event_type type)
{
        ktime_t                 now;
        s64                     delta; /* ns */
        DEFINE_IR_RAW_EVENT(ev);
        int                     rc = 0;
        int                     delay;

        if (!dev->raw)
                return -EINVAL;

        now = ktime_get();
        delta = ktime_to_ns(ktime_sub(now, dev->raw->last_event));
        delay = MS_TO_NS(dev->input_dev->rep[REP_DELAY]);

        /* Check for a long duration since last event or if we're
         * being called for the first time, note that delta can't
         * possibly be negative.
         */
        if (delta > delay || !dev->raw->last_type)
                type |= IR_START_EVENT;
        else
                ev.duration = delta;

        if (type & IR_START_EVENT)
                ir_raw_event_reset(dev);
        else if (dev->raw->last_type & IR_SPACE) {
                ev.pulse = false;
                rc = ir_raw_event_store(dev, &ev);
        } else if (dev->raw->last_type & IR_PULSE) {
                ev.pulse = true;
                rc = ir_raw_event_store(dev, &ev);
        } else
                return 0;

        dev->raw->last_event = now;
        dev->raw->last_type = type;
        return rc;
}
EXPORT_SYMBOL_GPL(ir_raw_event_store_edge);

/**
 * ir_raw_event_store_with_filter() - pass next pulse/space to decoders with some processing
 * @dev:        the struct rc_dev device descriptor
 * @type:       the type of the event that has occurred
 *
 * This routine (which may be called from an interrupt context) works
 * in similar manner to ir_raw_event_store_edge.
 * This routine is intended for devices with limited internal buffer
 * It automerges samples of same type, and handles timeouts. Returns non-zero
 * if the event was added, and zero if the event was ignored due to idle
 * processing.
 */
int ir_raw_event_store_with_filter(struct rc_dev *dev, struct ir_raw_event *ev)
{
        if (!dev->raw)
                return -EINVAL;

        /* Ignore spaces in idle mode */
        if (dev->idle && !ev->pulse)
                return 0;
        else if (dev->idle)
                ir_raw_event_set_idle(dev, false);

        if (!dev->raw->this_ev.duration)
                dev->raw->this_ev = *ev;
        else if (ev->pulse == dev->raw->this_ev.pulse)
                dev->raw->this_ev.duration += ev->duration;
        else {
                ir_raw_event_store(dev, &dev->raw->this_ev);
                dev->raw->this_ev = *ev;
        }

        /* Enter idle mode if nessesary */
        if (!ev->pulse && dev->timeout &&
            dev->raw->this_ev.duration >= dev->timeout)
                ir_raw_event_set_idle(dev, true);

        return 1;
}
EXPORT_SYMBOL_GPL(ir_raw_event_store_with_filter);

/**
 * ir_raw_event_set_idle() - provide hint to rc-core when the device is idle or not
 * @dev:        the struct rc_dev device descriptor
 * @idle:       whether the device is idle or not
 */
void ir_raw_event_set_idle(struct rc_dev *dev, bool idle)
{
        if (!dev->raw)
                return;

        IR_dprintk(2, "%s idle mode\n", idle ? "enter" : "leave");

        if (idle) {
                dev->raw->this_ev.timeout = true;
                ir_raw_event_store(dev, &dev->raw->this_ev);
                init_ir_raw_event(&dev->raw->this_ev);
        }

        if (dev->s_idle)
                dev->s_idle(dev, idle);

        dev->idle = idle;
}
EXPORT_SYMBOL_GPL(ir_raw_event_set_idle);

/**
 * ir_raw_event_handle() - schedules the decoding of stored ir data
 * @dev:        the struct rc_dev device descriptor
 *
 * This routine will tell rc-core to start decoding stored ir data.
 */
void ir_raw_event_handle(struct rc_dev *dev)
{
        unsigned long flags;

        if (!dev->raw)
                return;

        spin_lock_irqsave(&dev->raw->lock, flags);
        wake_up_process(dev->raw->thread);
        spin_unlock_irqrestore(&dev->raw->lock, flags);
}
EXPORT_SYMBOL_GPL(ir_raw_event_handle);

/* used internally by the sysfs interface */
u64
ir_raw_get_allowed_protocols(void)
{
        u64 protocols;
        mutex_lock(&available_protocols_lock);
        protocols = available_protocols;
        mutex_unlock(&available_protocols_lock);
        return protocols;
}

static int change_protocol(struct rc_dev *dev, u64 *rc_type)
{
        /* the caller will update dev->enabled_protocols */
        return 0;
}

static void ir_raw_disable_protocols(struct rc_dev *dev, u64 protocols)
{
        mutex_lock(&dev->lock);
        dev->enabled_protocols &= ~protocols;
        dev->enabled_wakeup_protocols &= ~protocols;
        mutex_unlock(&dev->lock);
}

/*
 * Used to (un)register raw event clients
 */
int ir_raw_event_register(struct rc_dev *dev)
{
        int rc;
        struct ir_raw_handler *handler;

        if (!dev)
                return -EINVAL;

        dev->raw = kzalloc(sizeof(*dev->raw), GFP_KERNEL);
        if (!dev->raw)
                return -ENOMEM;

        dev->raw->dev = dev;
        dev->change_protocol = change_protocol;
        INIT_KFIFO(dev->raw->kfifo);

        spin_lock_init(&dev->raw->lock);
        dev->raw->thread = kthread_run(ir_raw_event_thread, dev->raw,
                                       "rc%u", dev->minor);

        if (IS_ERR(dev->raw->thread)) {
                rc = PTR_ERR(dev->raw->thread);
                goto out;
        }

        mutex_lock(&ir_raw_handler_lock);
        list_add_tail(&dev->raw->list, &ir_raw_client_list);
        list_for_each_entry(handler, &ir_raw_handler_list, list)
                if (handler->raw_register)
                        handler->raw_register(dev);
        mutex_unlock(&ir_raw_handler_lock);

        return 0;

out:
        kfree(dev->raw);
        dev->raw = NULL;
        return rc;
}

void ir_raw_event_unregister(struct rc_dev *dev)
{
        struct ir_raw_handler *handler;

        if (!dev || !dev->raw)
                return;

        kthread_stop(dev->raw->thread);

        mutex_lock(&ir_raw_handler_lock);
        list_del(&dev->raw->list);
        list_for_each_entry(handler, &ir_raw_handler_list, list)
                if (handler->raw_unregister)
                        handler->raw_unregister(dev);
        mutex_unlock(&ir_raw_handler_lock);

        kfree(dev->raw);
        dev->raw = NULL;
}

/*
 * Extension interface - used to register the IR decoders
 */

int ir_raw_handler_register(struct ir_raw_handler *ir_raw_handler)
{
        struct ir_raw_event_ctrl *raw;

        mutex_lock(&ir_raw_handler_lock);
        list_add_tail(&ir_raw_handler->list, &ir_raw_handler_list);
        if (ir_raw_handler->raw_register)
                list_for_each_entry(raw, &ir_raw_client_list, list)
                        ir_raw_handler->raw_register(raw->dev);
        mutex_lock(&available_protocols_lock);
        available_protocols |= ir_raw_handler->protocols;
        mutex_unlock(&available_protocols_lock);
        mutex_unlock(&ir_raw_handler_lock);

        return 0;
}
EXPORT_SYMBOL(ir_raw_handler_register);

void ir_raw_handler_unregister(struct ir_raw_handler *ir_raw_handler)
{
        struct ir_raw_event_ctrl *raw;
        u64 protocols = ir_raw_handler->protocols;

        mutex_lock(&ir_raw_handler_lock);
        list_del(&ir_raw_handler->list);
        list_for_each_entry(raw, &ir_raw_client_list, list) {
                ir_raw_disable_protocols(raw->dev, protocols);
                if (ir_raw_handler->raw_unregister)
                        ir_raw_handler->raw_unregister(raw->dev);
        }
        mutex_lock(&available_protocols_lock);
        available_protocols &= ~protocols;
        mutex_unlock(&available_protocols_lock);
        mutex_unlock(&ir_raw_handler_lock);
}
EXPORT_SYMBOL(ir_raw_handler_unregister);