// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Loopback driver for rc-core,
 *
 * Copyright (c) 2010 David Härdeman <david@hardeman.nu>
 *
 * This driver receives TX data and passes it back as RX data,
 * which is useful for (scripted) debugging of rc-core without
 * having to use actual hardware.
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <media/rc-core.h>

#define DRIVER_NAME     "rc-loopback"
#define dprintk(x...)   if (debug) printk(KERN_INFO DRIVER_NAME ": " x)
#define RXMASK_REGULAR  0x1
#define RXMASK_LEARNING 0x2

static bool debug;

struct loopback_dev {
        struct rc_dev *dev;
        u32 txmask;
        u32 txcarrier;
        u32 txduty;
        bool idle;
        bool learning;
        bool carrierreport;
        u32 rxcarriermin;
        u32 rxcarriermax;
};

static struct loopback_dev loopdev;

static int loop_set_tx_mask(struct rc_dev *dev, u32 mask)
{
        struct loopback_dev *lodev = dev->priv;

        if ((mask & (RXMASK_REGULAR | RXMASK_LEARNING)) != mask) {
                dprintk("invalid tx mask: %u\n", mask);
                return -EINVAL;
        }

        dprintk("setting tx mask: %u\n", mask);
        lodev->txmask = mask;
        return 0;
}

static int loop_set_tx_carrier(struct rc_dev *dev, u32 carrier)
{
        struct loopback_dev *lodev = dev->priv;

        dprintk("setting tx carrier: %u\n", carrier);
        lodev->txcarrier = carrier;
        return 0;
}

static int loop_set_tx_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
{
        struct loopback_dev *lodev = dev->priv;

        if (duty_cycle < 1 || duty_cycle > 99) {
                dprintk("invalid duty cycle: %u\n", duty_cycle);
                return -EINVAL;
        }

        dprintk("setting duty cycle: %u\n", duty_cycle);
        lodev->txduty = duty_cycle;
        return 0;
}

static int loop_set_rx_carrier_range(struct rc_dev *dev, u32 min, u32 max)
{
        struct loopback_dev *lodev = dev->priv;

        if (min < 1 || min > max) {
                dprintk("invalid rx carrier range %u to %u\n", min, max);
                return -EINVAL;
        }

        dprintk("setting rx carrier range %u to %u\n", min, max);
        lodev->rxcarriermin = min;
        lodev->rxcarriermax = max;
        return 0;
}

static int loop_tx_ir(struct rc_dev *dev, unsigned *txbuf, unsigned count)
{
        struct loopback_dev *lodev = dev->priv;
        u32 rxmask;
        unsigned i;
        struct ir_raw_event rawir = {};

        if (lodev->txcarrier < lodev->rxcarriermin ||
            lodev->txcarrier > lodev->rxcarriermax) {
                dprintk("ignoring tx, carrier out of range\n");
                goto out;
        }

        if (lodev->learning)
                rxmask = RXMASK_LEARNING;
        else
                rxmask = RXMASK_REGULAR;

        if (!(rxmask & lodev->txmask)) {
                dprintk("ignoring tx, rx mask mismatch\n");
                goto out;
        }

        for (i = 0; i < count; i++) {
                rawir.pulse = i % 2 ? false : true;
                rawir.duration = txbuf[i];
                if (rawir.duration)
                        ir_raw_event_store_with_filter(dev, &rawir);
        }

        /* Fake a silence long enough to cause us to go idle */
        rawir.pulse = false;
        rawir.duration = dev->timeout;
        ir_raw_event_store_with_filter(dev, &rawir);

        ir_raw_event_handle(dev);

out:
        return count;
}

static void loop_set_idle(struct rc_dev *dev, bool enable)
{
        struct loopback_dev *lodev = dev->priv;

        if (lodev->idle != enable) {
                dprintk("%sing idle mode\n", enable ? "enter" : "exit");
                lodev->idle = enable;
        }
}

static int loop_set_learning_mode(struct rc_dev *dev, int enable)
{
        struct loopback_dev *lodev = dev->priv;

        if (lodev->learning != enable) {
                dprintk("%sing learning mode\n", enable ? "enter" : "exit");
                lodev->learning = !!enable;
        }

        return 0;
}

static int loop_set_carrier_report(struct rc_dev *dev, int enable)
{
        struct loopback_dev *lodev = dev->priv;

        if (lodev->carrierreport != enable) {
                dprintk("%sabling carrier reports\n", enable ? "en" : "dis");
                lodev->carrierreport = !!enable;
        }

        return 0;
}

static int loop_set_wakeup_filter(struct rc_dev *dev,
                                  struct rc_scancode_filter *sc)
{
        static const unsigned int max = 512;
        struct ir_raw_event *raw;
        int ret;
        int i;

        /* fine to disable filter */
        if (!sc->mask)
                return 0;

        /* encode the specified filter and loop it back */
        raw = kmalloc_array(max, sizeof(*raw), GFP_KERNEL);
        if (!raw)
                return -ENOMEM;

        ret = ir_raw_encode_scancode(dev->wakeup_protocol, sc->data, raw, max);
        /* still loop back the partial raw IR even if it's incomplete */
        if (ret == -ENOBUFS)
                ret = max;
        if (ret >= 0) {
                /* do the loopback */
                for (i = 0; i < ret; ++i)
                        ir_raw_event_store(dev, &raw[i]);
                ir_raw_event_handle(dev);

                ret = 0;
        }

        kfree(raw);

        return ret;
}

static int __init loop_init(void)
{
        struct rc_dev *rc;
        int ret;

        rc = rc_allocate_device(RC_DRIVER_IR_RAW);
        if (!rc) {
                printk(KERN_ERR DRIVER_NAME ": rc_dev allocation failed\n");
                return -ENOMEM;
        }

        rc->device_name         = "rc-core loopback device";
        rc->input_phys          = "rc-core/virtual";
        rc->input_id.bustype    = BUS_VIRTUAL;
        rc->input_id.version    = 1;
        rc->driver_name         = DRIVER_NAME;
        rc->map_name            = RC_MAP_EMPTY;
        rc->priv                = &loopdev;
        rc->allowed_protocols   = RC_PROTO_BIT_ALL_IR_DECODER;
        rc->allowed_wakeup_protocols = RC_PROTO_BIT_ALL_IR_ENCODER;
        rc->encode_wakeup       = true;
        rc->timeout             = MS_TO_US(100); /* 100 ms */
        rc->min_timeout         = 1;
        rc->max_timeout         = UINT_MAX;
        rc->rx_resolution       = 1;
        rc->tx_resolution       = 1;
        rc->s_tx_mask           = loop_set_tx_mask;
        rc->s_tx_carrier        = loop_set_tx_carrier;
        rc->s_tx_duty_cycle     = loop_set_tx_duty_cycle;
        rc->s_rx_carrier_range  = loop_set_rx_carrier_range;
        rc->tx_ir               = loop_tx_ir;
        rc->s_idle              = loop_set_idle;
        rc->s_learning_mode     = loop_set_learning_mode;
        rc->s_carrier_report    = loop_set_carrier_report;
        rc->s_wakeup_filter     = loop_set_wakeup_filter;

        loopdev.txmask          = RXMASK_REGULAR;
        loopdev.txcarrier       = 36000;
        loopdev.txduty          = 50;
        loopdev.rxcarriermin    = 1;
        loopdev.rxcarriermax    = ~0;
        loopdev.idle            = true;
        loopdev.learning        = false;
        loopdev.carrierreport   = false;

        ret = rc_register_device(rc);
        if (ret < 0) {
                printk(KERN_ERR DRIVER_NAME ": rc_dev registration failed\n");
                rc_free_device(rc);
                return ret;
        }

        loopdev.dev = rc;
        return 0;
}

static void __exit loop_exit(void)
{
        rc_unregister_device(loopdev.dev);
}

module_init(loop_init);
module_exit(loop_exit);

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Enable debug messages");

MODULE_DESCRIPTION("Loopback device for rc-core debugging");
MODULE_AUTHOR("David Härdeman <david@hardeman.nu>");
MODULE_LICENSE("GPL");