// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  cx18 buffer queues
 *
 *  Derived from ivtv-queue.c
 *
 *  Copyright (C) 2007  Hans Verkuil <hverkuil@xs4all.nl>
 *  Copyright (C) 2008  Andy Walls <awalls@md.metrocast.net>
 */

#include "cx18-driver.h"
#include "cx18-queue.h"
#include "cx18-streams.h"
#include "cx18-scb.h"
#include "cx18-io.h"

void cx18_buf_swap(struct cx18_buffer *buf)
{
        int i;

        for (i = 0; i < buf->bytesused; i += 4)
                swab32s((u32 *)(buf->buf + i));
}

void _cx18_mdl_swap(struct cx18_mdl *mdl)
{
        struct cx18_buffer *buf;

        list_for_each_entry(buf, &mdl->buf_list, list) {
                if (buf->bytesused == 0)
                        break;
                cx18_buf_swap(buf);
        }
}

void cx18_queue_init(struct cx18_queue *q)
{
        INIT_LIST_HEAD(&q->list);
        atomic_set(&q->depth, 0);
        q->bytesused = 0;
}

struct cx18_queue *_cx18_enqueue(struct cx18_stream *s, struct cx18_mdl *mdl,
                                 struct cx18_queue *q, int to_front)
{
        /* clear the mdl if it is not to be enqueued to the full queue */
        if (q != &s->q_full) {
                mdl->bytesused = 0;
                mdl->readpos = 0;
                mdl->m_flags = 0;
                mdl->skipped = 0;
                mdl->curr_buf = NULL;
        }

        /* q_busy is restricted to a max buffer count imposed by firmware */
        if (q == &s->q_busy &&
            atomic_read(&q->depth) >= CX18_MAX_FW_MDLS_PER_STREAM)
                q = &s->q_free;

        spin_lock(&q->lock);

        if (to_front)
                list_add(&mdl->list, &q->list); /* LIFO */
        else
                list_add_tail(&mdl->list, &q->list); /* FIFO */
        q->bytesused += mdl->bytesused - mdl->readpos;
        atomic_inc(&q->depth);

        spin_unlock(&q->lock);
        return q;
}

struct cx18_mdl *cx18_dequeue(struct cx18_stream *s, struct cx18_queue *q)
{
        struct cx18_mdl *mdl = NULL;

        spin_lock(&q->lock);
        if (!list_empty(&q->list)) {
                mdl = list_first_entry(&q->list, struct cx18_mdl, list);
                list_del_init(&mdl->list);
                q->bytesused -= mdl->bytesused - mdl->readpos;
                mdl->skipped = 0;
                atomic_dec(&q->depth);
        }
        spin_unlock(&q->lock);
        return mdl;
}

static void _cx18_mdl_update_bufs_for_cpu(struct cx18_stream *s,
                                          struct cx18_mdl *mdl)
{
        struct cx18_buffer *buf;
        u32 buf_size = s->buf_size;
        u32 bytesused = mdl->bytesused;

        list_for_each_entry(buf, &mdl->buf_list, list) {
                buf->readpos = 0;
                if (bytesused >= buf_size) {
                        buf->bytesused = buf_size;
                        bytesused -= buf_size;
                } else {
                        buf->bytesused = bytesused;
                        bytesused = 0;
                }
                cx18_buf_sync_for_cpu(s, buf);
        }
}

static inline void cx18_mdl_update_bufs_for_cpu(struct cx18_stream *s,
                                                struct cx18_mdl *mdl)
{
        struct cx18_buffer *buf;

        if (list_is_singular(&mdl->buf_list)) {
                buf = list_first_entry(&mdl->buf_list, struct cx18_buffer,
                                       list);
                buf->bytesused = mdl->bytesused;
                buf->readpos = 0;
                cx18_buf_sync_for_cpu(s, buf);
        } else {
                _cx18_mdl_update_bufs_for_cpu(s, mdl);
        }
}

struct cx18_mdl *cx18_queue_get_mdl(struct cx18_stream *s, u32 id,
        u32 bytesused)
{
        struct cx18 *cx = s->cx;
        struct cx18_mdl *mdl;
        struct cx18_mdl *tmp;
        struct cx18_mdl *ret = NULL;
        LIST_HEAD(sweep_up);

        /*
         * We don't have to acquire multiple q locks here, because we are
         * serialized by the single threaded work handler.
         * MDLs from the firmware will thus remain in order as
         * they are moved from q_busy to q_full or to the dvb ring buffer.
         */
        spin_lock(&s->q_busy.lock);
        list_for_each_entry_safe(mdl, tmp, &s->q_busy.list, list) {
                /*
                 * We should find what the firmware told us is done,
                 * right at the front of the queue.  If we don't, we likely have
                 * missed an mdl done message from the firmware.
                 * Once we skip an mdl repeatedly, relative to the size of
                 * q_busy, we have high confidence we've missed it.
                 */
                if (mdl->id != id) {
                        mdl->skipped++;
                        if (mdl->skipped >= atomic_read(&s->q_busy.depth)-1) {
                                /* mdl must have fallen out of rotation */
                                CX18_WARN("Skipped %s, MDL %d, %d times - it must have dropped out of rotation\n",
                                          s->name, mdl->id,
                                          mdl->skipped);
                                /* Sweep it up to put it back into rotation */
                                list_move_tail(&mdl->list, &sweep_up);
                                atomic_dec(&s->q_busy.depth);
                        }
                        continue;
                }
                /*
                 * We pull the desired mdl off of the queue here.  Something
                 * will have to put it back on a queue later.
                 */
                list_del_init(&mdl->list);
                atomic_dec(&s->q_busy.depth);
                ret = mdl;
                break;
        }
        spin_unlock(&s->q_busy.lock);

        /*
         * We found the mdl for which we were looking.  Get it ready for
         * the caller to put on q_full or in the dvb ring buffer.
         */
        if (ret != NULL) {
                ret->bytesused = bytesused;
                ret->skipped = 0;
                /* 0'ed readpos, m_flags & curr_buf when mdl went on q_busy */
                cx18_mdl_update_bufs_for_cpu(s, ret);
                if (s->type != CX18_ENC_STREAM_TYPE_TS)
                        set_bit(CX18_F_M_NEED_SWAP, &ret->m_flags);
        }

        /* Put any mdls the firmware is ignoring back into normal rotation */
        list_for_each_entry_safe(mdl, tmp, &sweep_up, list) {
                list_del_init(&mdl->list);
                cx18_enqueue(s, mdl, &s->q_free);
        }
        return ret;
}

/* Move all mdls of a queue, while flushing the mdl */
static void cx18_queue_flush(struct cx18_stream *s,
                             struct cx18_queue *q_src, struct cx18_queue *q_dst)
{
        struct cx18_mdl *mdl;

        /* It only makes sense to flush to q_free or q_idle */
        if (q_src == q_dst || q_dst == &s->q_full || q_dst == &s->q_busy)
                return;

        spin_lock(&q_src->lock);
        spin_lock(&q_dst->lock);
        while (!list_empty(&q_src->list)) {
                mdl = list_first_entry(&q_src->list, struct cx18_mdl, list);
                list_move_tail(&mdl->list, &q_dst->list);
                mdl->bytesused = 0;
                mdl->readpos = 0;
                mdl->m_flags = 0;
                mdl->skipped = 0;
                mdl->curr_buf = NULL;
                atomic_inc(&q_dst->depth);
        }
        cx18_queue_init(q_src);
        spin_unlock(&q_src->lock);
        spin_unlock(&q_dst->lock);
}

void cx18_flush_queues(struct cx18_stream *s)
{
        cx18_queue_flush(s, &s->q_busy, &s->q_free);
        cx18_queue_flush(s, &s->q_full, &s->q_free);
}

/*
 * Note, s->buf_pool is not protected by a lock,
 * the stream better not have *anything* going on when calling this
 */
void cx18_unload_queues(struct cx18_stream *s)
{
        struct cx18_queue *q_idle = &s->q_idle;
        struct cx18_mdl *mdl;
        struct cx18_buffer *buf;

        /* Move all MDLS to q_idle */
        cx18_queue_flush(s, &s->q_busy, q_idle);
        cx18_queue_flush(s, &s->q_full, q_idle);
        cx18_queue_flush(s, &s->q_free, q_idle);

        /* Reset MDL id's and move all buffers back to the stream's buf_pool */
        spin_lock(&q_idle->lock);
        list_for_each_entry(mdl, &q_idle->list, list) {
                while (!list_empty(&mdl->buf_list)) {
                        buf = list_first_entry(&mdl->buf_list,
                                               struct cx18_buffer, list);
                        list_move_tail(&buf->list, &s->buf_pool);
                        buf->bytesused = 0;
                        buf->readpos = 0;
                }
                mdl->id = s->mdl_base_idx; /* reset id to a "safe" value */
                /* all other mdl fields were cleared by cx18_queue_flush() */
        }
        spin_unlock(&q_idle->lock);
}

/*
 * Note, s->buf_pool is not protected by a lock,
 * the stream better not have *anything* going on when calling this
 */
void cx18_load_queues(struct cx18_stream *s)
{
        struct cx18 *cx = s->cx;
        struct cx18_mdl *mdl;
        struct cx18_buffer *buf;
        int mdl_id;
        int i;
        u32 partial_buf_size;

        /*
         * Attach buffers to MDLs, give the MDLs ids, and add MDLs to q_free
         * Excess MDLs are left on q_idle
         * Excess buffers are left in buf_pool and/or on an MDL in q_idle
         */
        mdl_id = s->mdl_base_idx;
        for (mdl = cx18_dequeue(s, &s->q_idle), i = s->bufs_per_mdl;
             mdl != NULL && i == s->bufs_per_mdl;
             mdl = cx18_dequeue(s, &s->q_idle)) {

                mdl->id = mdl_id;

                for (i = 0; i < s->bufs_per_mdl; i++) {
                        if (list_empty(&s->buf_pool))
                                break;

                        buf = list_first_entry(&s->buf_pool, struct cx18_buffer,
                                               list);
                        list_move_tail(&buf->list, &mdl->buf_list);

                        /* update the firmware's MDL array with this buffer */
                        cx18_writel(cx, buf->dma_handle,
                                    &cx->scb->cpu_mdl[mdl_id + i].paddr);
                        cx18_writel(cx, s->buf_size,
                                    &cx->scb->cpu_mdl[mdl_id + i].length);
                }

                if (i == s->bufs_per_mdl) {
                        /*
                         * The encoder doesn't honor s->mdl_size.  So in the
                         * case of a non-integral number of buffers to meet
                         * mdl_size, we lie about the size of the last buffer
                         * in the MDL to get the encoder to really only send
                         * us mdl_size bytes per MDL transfer.
                         */
                        partial_buf_size = s->mdl_size % s->buf_size;
                        if (partial_buf_size) {
                                cx18_writel(cx, partial_buf_size,
                                      &cx->scb->cpu_mdl[mdl_id + i - 1].length);
                        }
                        cx18_enqueue(s, mdl, &s->q_free);
                } else {
                        /* Not enough buffers for this MDL; we won't use it */
                        cx18_push(s, mdl, &s->q_idle);
                }
                mdl_id += i;
        }
}

void _cx18_mdl_sync_for_device(struct cx18_stream *s, struct cx18_mdl *mdl)
{
        int dma = s->dma;
        u32 buf_size = s->buf_size;
        struct pci_dev *pci_dev = s->cx->pci_dev;
        struct cx18_buffer *buf;

        list_for_each_entry(buf, &mdl->buf_list, list)
                pci_dma_sync_single_for_device(pci_dev, buf->dma_handle,
                                               buf_size, dma);
}

int cx18_stream_alloc(struct cx18_stream *s)
{
        struct cx18 *cx = s->cx;
        int i;

        if (s->buffers == 0)
                return 0;

        CX18_DEBUG_INFO("Allocate %s stream: %d x %d buffers (%d.%02d kB total)\n",
                s->name, s->buffers, s->buf_size,
                s->buffers * s->buf_size / 1024,
                (s->buffers * s->buf_size * 100 / 1024) % 100);

        if (((char __iomem *)&cx->scb->cpu_mdl[cx->free_mdl_idx + s->buffers] -
                                (char __iomem *)cx->scb) > SCB_RESERVED_SIZE) {
                unsigned bufsz = (((char __iomem *)cx->scb) + SCB_RESERVED_SIZE -
                                        ((char __iomem *)cx->scb->cpu_mdl));

                CX18_ERR("Too many buffers, cannot fit in SCB area\n");
                CX18_ERR("Max buffers = %zu\n",
                        bufsz / sizeof(struct cx18_mdl_ent));
                return -ENOMEM;
        }

        s->mdl_base_idx = cx->free_mdl_idx;

        /* allocate stream buffers and MDLs */
        for (i = 0; i < s->buffers; i++) {
                struct cx18_mdl *mdl;
                struct cx18_buffer *buf;

                /* 1 MDL per buffer to handle the worst & also default case */
                mdl = kzalloc(sizeof(struct cx18_mdl), GFP_KERNEL|__GFP_NOWARN);
                if (mdl == NULL)
                        break;

                buf = kzalloc(sizeof(struct cx18_buffer),
                                GFP_KERNEL|__GFP_NOWARN);
                if (buf == NULL) {
                        kfree(mdl);
                        break;
                }

                buf->buf = kmalloc(s->buf_size, GFP_KERNEL|__GFP_NOWARN);
                if (buf->buf == NULL) {
                        kfree(mdl);
                        kfree(buf);
                        break;
                }

                INIT_LIST_HEAD(&mdl->list);
                INIT_LIST_HEAD(&mdl->buf_list);
                mdl->id = s->mdl_base_idx; /* a somewhat safe value */
                cx18_enqueue(s, mdl, &s->q_idle);

                INIT_LIST_HEAD(&buf->list);
                buf->dma_handle = pci_map_single(s->cx->pci_dev,
                                buf->buf, s->buf_size, s->dma);
                cx18_buf_sync_for_cpu(s, buf);
                list_add_tail(&buf->list, &s->buf_pool);
        }
        if (i == s->buffers) {
                cx->free_mdl_idx += s->buffers;
                return 0;
        }
        CX18_ERR("Couldn't allocate buffers for %s stream\n", s->name);
        cx18_stream_free(s);
        return -ENOMEM;
}

void cx18_stream_free(struct cx18_stream *s)
{
        struct cx18_mdl *mdl;
        struct cx18_buffer *buf;
        struct cx18 *cx = s->cx;

        CX18_DEBUG_INFO("Deallocating buffers for %s stream\n", s->name);

        /* move all buffers to buf_pool and all MDLs to q_idle */
        cx18_unload_queues(s);

        /* empty q_idle */
        while ((mdl = cx18_dequeue(s, &s->q_idle)))
                kfree(mdl);

        /* empty buf_pool */
        while (!list_empty(&s->buf_pool)) {
                buf = list_first_entry(&s->buf_pool, struct cx18_buffer, list);
                list_del_init(&buf->list);

                pci_unmap_single(s->cx->pci_dev, buf->dma_handle,
                                s->buf_size, s->dma);
                kfree(buf->buf);
                kfree(buf);
        }
}