// SPDX-License-Identifier: GPL-2.0
// rc-ir-raw.c - handle IR pulse/space events
//
// Copyright (C) 2010 by Mauro Carvalho Chehab

#include <linux/export.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/kmod.h>
#include <linux/sched.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 */
DEFINE_MUTEX(ir_raw_handler_lock);
static LIST_HEAD(ir_raw_handler_list);
static atomic64_t available_protocols = ATOMIC64_INIT(0);

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

        while (1) {
                mutex_lock(&ir_raw_handler_lock);
                while (kfifo_out(&raw->kfifo, &ev, 1)) {
                        if (is_timing_event(ev)) {
                                if (ev.duration == 0)
                                        dev_warn_once(&dev->dev, "nonsensical timing event of duration 0");
                                if (is_timing_event(raw->prev_ev) &&
                                    !is_transition(&ev, &raw->prev_ev))
                                        dev_warn_once(&dev->dev, "two consecutive events of type %s",
                                                      TO_STR(ev.pulse));
                        }
                        list_for_each_entry(handler, &ir_raw_handler_list, list)
                                if (dev->enabled_protocols &
                                    handler->protocols || !handler->protocols)
                                        handler->decode(dev, ev);
                        lirc_raw_event(dev, ev);
                        raw->prev_ev = ev;
                }
                mutex_unlock(&ir_raw_handler_lock);

                set_current_state(TASK_INTERRUPTIBLE);

                if (kthread_should_stop()) {
                        __set_current_state(TASK_RUNNING);
                        break;
                } else if (!kfifo_is_empty(&raw->kfifo))
                        set_current_state(TASK_RUNNING);

                schedule();
        }

        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;

        dev_dbg(&dev->dev, "sample: (%05dus %s)\n",
                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
 * @pulse:      true for pulse, false for space
 *
 * 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, bool pulse)
{
        ktime_t                 now;
        struct ir_raw_event     ev = {};

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

        now = ktime_get();
        ev.duration = ktime_to_us(ktime_sub(now, dev->raw->last_event));
        ev.pulse = !pulse;

        return ir_raw_event_store_with_timeout(dev, &ev);
}
EXPORT_SYMBOL_GPL(ir_raw_event_store_edge);

/*
 * ir_raw_event_store_with_timeout() - pass a pulse/space duration to the raw
 *                                     ir decoders, schedule decoding and
 *                                     timeout
 * @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, schedules
 * decoding and generates a timeout.
 */
int ir_raw_event_store_with_timeout(struct rc_dev *dev, struct ir_raw_event *ev)
{
        ktime_t         now;
        int             rc = 0;

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

        now = ktime_get();

        spin_lock(&dev->raw->edge_spinlock);
        rc = ir_raw_event_store(dev, ev);

        dev->raw->last_event = now;

        /* timer could be set to timeout (125ms by default) */
        if (!timer_pending(&dev->raw->edge_handle) ||
            time_after(dev->raw->edge_handle.expires,
                       jiffies + msecs_to_jiffies(15))) {
                mod_timer(&dev->raw->edge_handle,
                          jiffies + msecs_to_jiffies(15));
        }
        spin_unlock(&dev->raw->edge_spinlock);

        return rc;
}
EXPORT_SYMBOL_GPL(ir_raw_event_store_with_timeout);

/**
 * ir_raw_event_store_with_filter() - pass next pulse/space to decoders with some processing
 * @dev:        the struct rc_dev device descriptor
 * @ev:         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 necessary */
        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;

        dev_dbg(&dev->dev, "%s idle mode\n", idle ? "enter" : "leave");

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

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

        wake_up_process(dev->raw->thread);
}
EXPORT_SYMBOL_GPL(ir_raw_event_handle);

/* used internally by the sysfs interface */
u64
ir_raw_get_allowed_protocols(void)
{
        return atomic64_read(&available_protocols);
}

static int change_protocol(struct rc_dev *dev, u64 *rc_proto)
{
        struct ir_raw_handler *handler;
        u32 timeout = 0;

        mutex_lock(&ir_raw_handler_lock);
        list_for_each_entry(handler, &ir_raw_handler_list, list) {
                if (!(dev->enabled_protocols & handler->protocols) &&
                    (*rc_proto & handler->protocols) && handler->raw_register)
                        handler->raw_register(dev);

                if ((dev->enabled_protocols & handler->protocols) &&
                    !(*rc_proto & handler->protocols) &&
                    handler->raw_unregister)
                        handler->raw_unregister(dev);
        }
        mutex_unlock(&ir_raw_handler_lock);

        if (!dev->max_timeout)
                return 0;

        mutex_lock(&ir_raw_handler_lock);
        list_for_each_entry(handler, &ir_raw_handler_list, list) {
                if (handler->protocols & *rc_proto) {
                        if (timeout < handler->min_timeout)
                                timeout = handler->min_timeout;
                }
        }
        mutex_unlock(&ir_raw_handler_lock);

        if (timeout == 0)
                timeout = IR_DEFAULT_TIMEOUT;
        else
                timeout += MS_TO_US(10);

        if (timeout < dev->min_timeout)
                timeout = dev->min_timeout;
        else if (timeout > dev->max_timeout)
                timeout = dev->max_timeout;

        if (dev->s_timeout)
                dev->s_timeout(dev, timeout);
        else
                dev->timeout = timeout;

        return 0;
}

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

/**
 * ir_raw_gen_manchester() - Encode data with Manchester (bi-phase) modulation.
 * @ev:         Pointer to pointer to next free event. *@ev is incremented for
 *              each raw event filled.
 * @max:        Maximum number of raw events to fill.
 * @timings:    Manchester modulation timings.
 * @n:          Number of bits of data.
 * @data:       Data bits to encode.
 *
 * Encodes the @n least significant bits of @data using Manchester (bi-phase)
 * modulation with the timing characteristics described by @timings, writing up
 * to @max raw IR events using the *@ev pointer.
 *
 * Returns:     0 on success.
 *              -ENOBUFS if there isn't enough space in the array to fit the
 *              full encoded data. In this case all @max events will have been
 *              written.
 */
int ir_raw_gen_manchester(struct ir_raw_event **ev, unsigned int max,
                          const struct ir_raw_timings_manchester *timings,
                          unsigned int n, u64 data)
{
        bool need_pulse;
        u64 i;
        int ret = -ENOBUFS;

        i = BIT_ULL(n - 1);

        if (timings->leader_pulse) {
                if (!max--)
                        return ret;
                init_ir_raw_event_duration((*ev), 1, timings->leader_pulse);
                if (timings->leader_space) {
                        if (!max--)
                                return ret;
                        init_ir_raw_event_duration(++(*ev), 0,
                                                   timings->leader_space);
                }
        } else {
                /* continue existing signal */
                --(*ev);
        }
        /* from here on *ev will point to the last event rather than the next */

        while (n && i > 0) {
                need_pulse = !(data & i);
                if (timings->invert)
                        need_pulse = !need_pulse;
                if (need_pulse == !!(*ev)->pulse) {
                        (*ev)->duration += timings->clock;
                } else {
                        if (!max--)
                                goto nobufs;
                        init_ir_raw_event_duration(++(*ev), need_pulse,
                                                   timings->clock);
                }

                if (!max--)
                        goto nobufs;
                init_ir_raw_event_duration(++(*ev), !need_pulse,
                                           timings->clock);
                i >>= 1;
        }

        if (timings->trailer_space) {
                if (!(*ev)->pulse)
                        (*ev)->duration += timings->trailer_space;
                else if (!max--)
                        goto nobufs;
                else
                        init_ir_raw_event_duration(++(*ev), 0,
                                                   timings->trailer_space);
        }

        ret = 0;
nobufs:
        /* point to the next event rather than last event before returning */
        ++(*ev);
        return ret;
}
EXPORT_SYMBOL(ir_raw_gen_manchester);

/**
 * ir_raw_gen_pd() - Encode data to raw events with pulse-distance modulation.
 * @ev:         Pointer to pointer to next free event. *@ev is incremented for
 *              each raw event filled.
 * @max:        Maximum number of raw events to fill.
 * @timings:    Pulse distance modulation timings.
 * @n:          Number of bits of data.
 * @data:       Data bits to encode.
 *
 * Encodes the @n least significant bits of @data using pulse-distance
 * modulation with the timing characteristics described by @timings, writing up
 * to @max raw IR events using the *@ev pointer.
 *
 * Returns:     0 on success.
 *              -ENOBUFS if there isn't enough space in the array to fit the
 *              full encoded data. In this case all @max events will have been
 *              written.
 */
int ir_raw_gen_pd(struct ir_raw_event **ev, unsigned int max,
                  const struct ir_raw_timings_pd *timings,
                  unsigned int n, u64 data)
{
        int i;
        int ret;
        unsigned int space;

        if (timings->header_pulse) {
                ret = ir_raw_gen_pulse_space(ev, &max, timings->header_pulse,
                                             timings->header_space);
                if (ret)
                        return ret;
        }

        if (timings->msb_first) {
                for (i = n - 1; i >= 0; --i) {
                        space = timings->bit_space[(data >> i) & 1];
                        ret = ir_raw_gen_pulse_space(ev, &max,
                                                     timings->bit_pulse,
                                                     space);
                        if (ret)
                                return ret;
                }
        } else {
                for (i = 0; i < n; ++i, data >>= 1) {
                        space = timings->bit_space[data & 1];
                        ret = ir_raw_gen_pulse_space(ev, &max,
                                                     timings->bit_pulse,
                                                     space);
                        if (ret)
                                return ret;
                }
        }

        ret = ir_raw_gen_pulse_space(ev, &max, timings->trailer_pulse,
                                     timings->trailer_space);
        return ret;
}
EXPORT_SYMBOL(ir_raw_gen_pd);

/**
 * ir_raw_gen_pl() - Encode data to raw events with pulse-length modulation.
 * @ev:         Pointer to pointer to next free event. *@ev is incremented for
 *              each raw event filled.
 * @max:        Maximum number of raw events to fill.
 * @timings:    Pulse distance modulation timings.
 * @n:          Number of bits of data.
 * @data:       Data bits to encode.
 *
 * Encodes the @n least significant bits of @data using space-distance
 * modulation with the timing characteristics described by @timings, writing up
 * to @max raw IR events using the *@ev pointer.
 *
 * Returns:     0 on success.
 *              -ENOBUFS if there isn't enough space in the array to fit the
 *              full encoded data. In this case all @max events will have been
 *              written.
 */
int ir_raw_gen_pl(struct ir_raw_event **ev, unsigned int max,
                  const struct ir_raw_timings_pl *timings,
                  unsigned int n, u64 data)
{
        int i;
        int ret = -ENOBUFS;
        unsigned int pulse;

        if (!max--)
                return ret;

        init_ir_raw_event_duration((*ev)++, 1, timings->header_pulse);

        if (timings->msb_first) {
                for (i = n - 1; i >= 0; --i) {
                        if (!max--)
                                return ret;
                        init_ir_raw_event_duration((*ev)++, 0,
                                                   timings->bit_space);
                        if (!max--)
                                return ret;
                        pulse = timings->bit_pulse[(data >> i) & 1];
                        init_ir_raw_event_duration((*ev)++, 1, pulse);
                }
        } else {
                for (i = 0; i < n; ++i, data >>= 1) {
                        if (!max--)
                                return ret;
                        init_ir_raw_event_duration((*ev)++, 0,
                                                   timings->bit_space);
                        if (!max--)
                                return ret;
                        pulse = timings->bit_pulse[data & 1];
                        init_ir_raw_event_duration((*ev)++, 1, pulse);
                }
        }

        if (!max--)
                return ret;

        init_ir_raw_event_duration((*ev)++, 0, timings->trailer_space);

        return 0;
}
EXPORT_SYMBOL(ir_raw_gen_pl);

/**
 * ir_raw_encode_scancode() - Encode a scancode as raw events
 *
 * @protocol:           protocol
 * @scancode:           scancode filter describing a single scancode
 * @events:             array of raw events to write into
 * @max:                max number of raw events
 *
 * Attempts to encode the scancode as raw events.
 *
 * Returns:     The number of events written.
 *              -ENOBUFS if there isn't enough space in the array to fit the
 *              encoding. In this case all @max events will have been written.
 *              -EINVAL if the scancode is ambiguous or invalid, or if no
 *              compatible encoder was found.
 */
int ir_raw_encode_scancode(enum rc_proto protocol, u32 scancode,
                           struct ir_raw_event *events, unsigned int max)
{
        struct ir_raw_handler *handler;
        int ret = -EINVAL;
        u64 mask = 1ULL << protocol;

        ir_raw_load_modules(&mask);

        mutex_lock(&ir_raw_handler_lock);
        list_for_each_entry(handler, &ir_raw_handler_list, list) {
                if (handler->protocols & mask && handler->encode) {
                        ret = handler->encode(protocol, scancode, events, max);
                        if (ret >= 0 || ret == -ENOBUFS)
                                break;
                }
        }
        mutex_unlock(&ir_raw_handler_lock);

        return ret;
}
EXPORT_SYMBOL(ir_raw_encode_scancode);

/**
 * ir_raw_edge_handle() - Handle ir_raw_event_store_edge() processing
 *
 * @t:          timer_list
 *
 * This callback is armed by ir_raw_event_store_edge(). It does two things:
 * first of all, rather than calling ir_raw_event_handle() for each
 * edge and waking up the rc thread, 15 ms after the first edge
 * ir_raw_event_handle() is called. Secondly, generate a timeout event
 * no more IR is received after the rc_dev timeout.
 */
static void ir_raw_edge_handle(struct timer_list *t)
{
        struct ir_raw_event_ctrl *raw = timer_container_of(raw, t,
                                                           edge_handle);
        struct rc_dev *dev = raw->dev;
        unsigned long flags;
        ktime_t interval;

        spin_lock_irqsave(&dev->raw->edge_spinlock, flags);
        interval = ktime_sub(ktime_get(), dev->raw->last_event);
        if (ktime_to_us(interval) >= dev->timeout) {
                struct ir_raw_event ev = {
                        .timeout = true,
                        .duration = ktime_to_us(interval)
                };

                ir_raw_event_store(dev, &ev);
        } else {
                mod_timer(&dev->raw->edge_handle,
                          jiffies + usecs_to_jiffies(dev->timeout -
                                                     ktime_to_us(interval)));
        }
        spin_unlock_irqrestore(&dev->raw->edge_spinlock, flags);

        ir_raw_event_handle(dev);
}

/**
 * ir_raw_encode_carrier() - Get carrier used for protocol
 *
 * @protocol:           protocol
 *
 * Attempts to find the carrier for the specified protocol
 *
 * Returns:     The carrier in Hz
 *              -EINVAL if the protocol is invalid, or if no
 *              compatible encoder was found.
 */
int ir_raw_encode_carrier(enum rc_proto protocol)
{
        struct ir_raw_handler *handler;
        int ret = -EINVAL;
        u64 mask = BIT_ULL(protocol);

        mutex_lock(&ir_raw_handler_lock);
        list_for_each_entry(handler, &ir_raw_handler_list, list) {
                if (handler->protocols & mask && handler->encode) {
                        ret = handler->carrier;
                        break;
                }
        }
        mutex_unlock(&ir_raw_handler_lock);

        return ret;
}
EXPORT_SYMBOL(ir_raw_encode_carrier);

/*
 * Used to (un)register raw event clients
 */
int ir_raw_event_prepare(struct rc_dev *dev)
{
        if (!dev)
                return -EINVAL;

        dev->raw = kzalloc_obj(*dev->raw);
        if (!dev->raw)
                return -ENOMEM;

        dev->raw->dev = dev;
        dev->change_protocol = change_protocol;
        dev->idle = true;
        spin_lock_init(&dev->raw->edge_spinlock);
        timer_setup(&dev->raw->edge_handle, ir_raw_edge_handle, 0);
        INIT_KFIFO(dev->raw->kfifo);

        return 0;
}

int ir_raw_event_register(struct rc_dev *dev)
{
        struct task_struct *thread;

        thread = kthread_run(ir_raw_event_thread, dev->raw, "rc%u", dev->minor);
        if (IS_ERR(thread))
                return PTR_ERR(thread);

        dev->raw->thread = thread;

        mutex_lock(&ir_raw_handler_lock);
        list_add_tail(&dev->raw->list, &ir_raw_client_list);
        mutex_unlock(&ir_raw_handler_lock);

        return 0;
}

void ir_raw_event_free(struct rc_dev *dev)
{
        if (!dev)
                return;

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

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

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

        kthread_stop(dev->raw->thread);
        timer_delete_sync(&dev->raw->edge_handle);

        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->protocols & dev->enabled_protocols))
                        handler->raw_unregister(dev);

        lirc_bpf_free(dev);

        ir_raw_event_free(dev);

        /*
         * A user can be calling bpf(BPF_PROG_{QUERY|ATTACH|DETACH}), so
         * ensure that the raw member is null on unlock; this is how
         * "device gone" is checked.
         */
        mutex_unlock(&ir_raw_handler_lock);
}

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

int ir_raw_handler_register(struct ir_raw_handler *ir_raw_handler)
{
        mutex_lock(&ir_raw_handler_lock);
        list_add_tail(&ir_raw_handler->list, &ir_raw_handler_list);
        atomic64_or(ir_raw_handler->protocols, &available_protocols);
        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) {
                if (ir_raw_handler->raw_unregister &&
                    (raw->dev->enabled_protocols & protocols))
                        ir_raw_handler->raw_unregister(raw->dev);
                ir_raw_disable_protocols(raw->dev, protocols);
        }
        atomic64_andnot(protocols, &available_protocols);
        mutex_unlock(&ir_raw_handler_lock);
}
EXPORT_SYMBOL(ir_raw_handler_unregister);