// SPDX-License-Identifier: GPL-2.0-only
/*
 * ngene-dvb.c: nGene PCIe bridge driver - DVB functions
 *
 * Copyright (C) 2005-2007 Micronas
 *
 * Copyright (C) 2008-2009 Ralph Metzler <rjkm@metzlerbros.de>
 *                         Modifications for new nGene firmware,
 *                         support for EEPROM-copying,
 *                         support for new dual DVB-S2 card prototype
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/io.h>
#include <asm/div64.h>
#include <linux/pci.h>
#include <linux/timer.h>
#include <linux/byteorder/generic.h>
#include <linux/firmware.h>
#include <linux/vmalloc.h>

#include "ngene.h"

static int ci_tsfix = 1;
module_param(ci_tsfix, int, 0444);
MODULE_PARM_DESC(ci_tsfix, "Detect and fix TS buffer offset shifts in conjunction with CI expansions (default: 1/enabled)");

/****************************************************************************/
/* COMMAND API interface ****************************************************/
/****************************************************************************/

static ssize_t ts_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
        struct dvb_device *dvbdev = file->private_data;
        struct ngene_channel *chan = dvbdev->priv;
        struct ngene *dev = chan->dev;

        if (wait_event_interruptible(dev->tsout_rbuf.queue,
                                     dvb_ringbuffer_free
                                     (&dev->tsout_rbuf) >= count) < 0)
                return 0;

        dvb_ringbuffer_write_user(&dev->tsout_rbuf, buf, count);

        return count;
}

static ssize_t ts_read(struct file *file, char __user *buf,
                       size_t count, loff_t *ppos)
{
        struct dvb_device *dvbdev = file->private_data;
        struct ngene_channel *chan = dvbdev->priv;
        struct ngene *dev = chan->dev;
        int left, avail;

        left = count;
        while (left) {
                if (wait_event_interruptible(
                            dev->tsin_rbuf.queue,
                            dvb_ringbuffer_avail(&dev->tsin_rbuf) > 0) < 0)
                        return -EAGAIN;
                avail = dvb_ringbuffer_avail(&dev->tsin_rbuf);
                if (avail > left)
                        avail = left;
                dvb_ringbuffer_read_user(&dev->tsin_rbuf, buf, avail);
                left -= avail;
                buf += avail;
        }
        return count;
}

static __poll_t ts_poll(struct file *file, poll_table *wait)
{
        struct dvb_device *dvbdev = file->private_data;
        struct ngene_channel *chan = dvbdev->priv;
        struct ngene *dev = chan->dev;
        struct dvb_ringbuffer *rbuf = &dev->tsin_rbuf;
        struct dvb_ringbuffer *wbuf = &dev->tsout_rbuf;
        __poll_t mask = 0;

        poll_wait(file, &rbuf->queue, wait);
        poll_wait(file, &wbuf->queue, wait);

        if (!dvb_ringbuffer_empty(rbuf))
                mask |= EPOLLIN | EPOLLRDNORM;
        if (dvb_ringbuffer_free(wbuf) >= 188)
                mask |= EPOLLOUT | EPOLLWRNORM;

        return mask;
}

static const struct file_operations ci_fops = {
        .owner   = THIS_MODULE,
        .read    = ts_read,
        .write   = ts_write,
        .open    = dvb_generic_open,
        .release = dvb_generic_release,
        .poll    = ts_poll,
        .mmap    = NULL,
};

struct dvb_device ngene_dvbdev_ci = {
        .priv    = NULL,
        .readers = 1,
        .writers = 1,
        .users   = 2,
        .fops    = &ci_fops,
};


/****************************************************************************/
/* DVB functions and API interface ******************************************/
/****************************************************************************/

static void swap_buffer(u32 *p, u32 len)
{
        while (len) {
                *p = swab32(*p);
                p++;
                len -= 4;
        }
}

/* start of filler packet */
static u8 fill_ts[] = { 0x47, 0x1f, 0xff, 0x10, TS_FILLER };

static int tsin_find_offset(void *buf, u32 len)
{
        int i, l;

        l = len - sizeof(fill_ts);
        if (l <= 0)
                return -1;

        for (i = 0; i < l; i++) {
                if (((char *)buf)[i] == 0x47) {
                        if (!memcmp(buf + i, fill_ts, sizeof(fill_ts)))
                                return i % 188;
                }
        }

        return -1;
}

static inline void tsin_copy_stripped(struct ngene *dev, void *buf)
{
        if (memcmp(buf, fill_ts, sizeof(fill_ts)) != 0) {
                if (dvb_ringbuffer_free(&dev->tsin_rbuf) >= 188) {
                        dvb_ringbuffer_write(&dev->tsin_rbuf, buf, 188);
                        wake_up(&dev->tsin_rbuf.queue);
                }
        }
}

void *tsin_exchange(void *priv, void *buf, u32 len, u32 clock, u32 flags)
{
        struct ngene_channel *chan = priv;
        struct ngene *dev = chan->dev;
        int tsoff;

        if (flags & DF_SWAP32)
                swap_buffer(buf, len);

        if (dev->ci.en && chan->number == 2) {
                /* blindly copy buffers if ci_tsfix is disabled */
                if (!ci_tsfix) {
                        while (len >= 188) {
                                tsin_copy_stripped(dev, buf);

                                buf += 188;
                                len -= 188;
                        }
                        return NULL;
                }

                /* ci_tsfix = 1 */

                /*
                 * since the remainder of the TS packet which got cut off
                 * in the previous tsin_exchange() run is at the beginning
                 * of the new TS buffer, append this to the temp buffer and
                 * send it to the DVB ringbuffer afterwards.
                 */
                if (chan->tsin_offset) {
                        memcpy(&chan->tsin_buffer[(188 - chan->tsin_offset)],
                               buf, chan->tsin_offset);
                        tsin_copy_stripped(dev, &chan->tsin_buffer);

                        buf += chan->tsin_offset;
                        len -= chan->tsin_offset;
                }

                /*
                 * copy TS packets to the DVB ringbuffer and detect new offset
                 * shifts by checking for a valid TS SYNC byte
                 */
                while (len >= 188) {
                        if (*((char *)buf) != 0x47) {
                                /*
                                 * no SYNC header, find new offset shift
                                 * (max. 188 bytes, tsoff will be mod 188)
                                 */
                                tsoff = tsin_find_offset(buf, len);
                                if (tsoff > 0) {
                                        chan->tsin_offset += tsoff;
                                        chan->tsin_offset %= 188;

                                        buf += tsoff;
                                        len -= tsoff;

                                        dev_info(&dev->pci_dev->dev,
                                                 "%s(): tsin_offset shift by %d on channel %d\n",
                                                 __func__, tsoff,
                                                 chan->number);

                                        /*
                                         * offset corrected. re-check remaining
                                         * len for a full TS frame, break and
                                         * skip to fragment handling if < 188.
                                         */
                                        if (len < 188)
                                                break;
                                }
                        }

                        tsin_copy_stripped(dev, buf);

                        buf += 188;
                        len -= 188;
                }

                /*
                 * if a fragment is left, copy to temp buffer. The remainder
                 * will be appended in the next tsin_exchange() iteration.
                 */
                if (len > 0 && len < 188)
                        memcpy(&chan->tsin_buffer, buf, len);

                return NULL;
        }

        if (chan->users > 0)
                dvb_dmx_swfilter(&chan->demux, buf, len);

        return NULL;
}

void *tsout_exchange(void *priv, void *buf, u32 len, u32 clock, u32 flags)
{
        struct ngene_channel *chan = priv;
        struct ngene *dev = chan->dev;
        u32 alen;

        alen = dvb_ringbuffer_avail(&dev->tsout_rbuf);
        alen -= alen % 188;

        if (alen < len)
                FillTSBuffer(buf + alen, len - alen, flags);
        else
                alen = len;
        dvb_ringbuffer_read(&dev->tsout_rbuf, buf, alen);
        if (flags & DF_SWAP32)
                swap_buffer((u32 *)buf, alen);
        wake_up_interruptible(&dev->tsout_rbuf.queue);
        return buf;
}



int ngene_start_feed(struct dvb_demux_feed *dvbdmxfeed)
{
        struct dvb_demux *dvbdmx = dvbdmxfeed->demux;
        struct ngene_channel *chan = dvbdmx->priv;

        if (chan->users == 0) {
                if (!chan->dev->cmd_timeout_workaround || !chan->running)
                        set_transfer(chan, 1);
        }

        return ++chan->users;
}

int ngene_stop_feed(struct dvb_demux_feed *dvbdmxfeed)
{
        struct dvb_demux *dvbdmx = dvbdmxfeed->demux;
        struct ngene_channel *chan = dvbdmx->priv;

        if (--chan->users)
                return chan->users;

        if (!chan->dev->cmd_timeout_workaround)
                set_transfer(chan, 0);

        return 0;
}

int my_dvb_dmx_ts_card_init(struct dvb_demux *dvbdemux, char *id,
                            int (*start_feed)(struct dvb_demux_feed *),
                            int (*stop_feed)(struct dvb_demux_feed *),
                            void *priv)
{
        dvbdemux->priv = priv;

        dvbdemux->filternum = 256;
        dvbdemux->feednum = 256;
        dvbdemux->start_feed = start_feed;
        dvbdemux->stop_feed = stop_feed;
        dvbdemux->write_to_decoder = NULL;
        dvbdemux->dmx.capabilities = (DMX_TS_FILTERING |
                                      DMX_SECTION_FILTERING |
                                      DMX_MEMORY_BASED_FILTERING);
        return dvb_dmx_init(dvbdemux);
}

int my_dvb_dmxdev_ts_card_init(struct dmxdev *dmxdev,
                               struct dvb_demux *dvbdemux,
                               struct dmx_frontend *hw_frontend,
                               struct dmx_frontend *mem_frontend,
                               struct dvb_adapter *dvb_adapter)
{
        int ret;

        dmxdev->filternum = 256;
        dmxdev->demux = &dvbdemux->dmx;
        dmxdev->capabilities = 0;
        ret = dvb_dmxdev_init(dmxdev, dvb_adapter);
        if (ret < 0)
                return ret;

        hw_frontend->source = DMX_FRONTEND_0;
        dvbdemux->dmx.add_frontend(&dvbdemux->dmx, hw_frontend);
        mem_frontend->source = DMX_MEMORY_FE;
        dvbdemux->dmx.add_frontend(&dvbdemux->dmx, mem_frontend);
        return dvbdemux->dmx.connect_frontend(&dvbdemux->dmx, hw_frontend);
}