/*
 * Copyright (c) 2017, NVIDIA CORPORATION. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 */
#include "qmgr.h"

static void
nvkm_falcon_msgq_open(struct nvkm_falcon_msgq *msgq)
{
        mutex_lock(&msgq->mutex);
        msgq->position = nvkm_falcon_rd32(msgq->qmgr->falcon, msgq->tail_reg);
}

static void
nvkm_falcon_msgq_close(struct nvkm_falcon_msgq *msgq, bool commit)
{
        struct nvkm_falcon *falcon = msgq->qmgr->falcon;

        if (commit)
                nvkm_falcon_wr32(falcon, msgq->tail_reg, msgq->position);

        mutex_unlock(&msgq->mutex);
}

static bool
nvkm_falcon_msgq_empty(struct nvkm_falcon_msgq *msgq)
{
        u32 head = nvkm_falcon_rd32(msgq->qmgr->falcon, msgq->head_reg);
        u32 tail = nvkm_falcon_rd32(msgq->qmgr->falcon, msgq->tail_reg);
        return head == tail;
}

static int
nvkm_falcon_msgq_pop(struct nvkm_falcon_msgq *msgq, void *data, u32 size)
{
        struct nvkm_falcon *falcon = msgq->qmgr->falcon;
        u32 head, tail, available;

        head = nvkm_falcon_rd32(falcon, msgq->head_reg);
        /* has the buffer looped? */
        if (head < msgq->position)
                msgq->position = msgq->offset;

        tail = msgq->position;

        available = head - tail;
        if (size > available) {
                FLCNQ_ERR(msgq, "requested %d bytes, but only %d available",
                          size, available);
                return -EINVAL;
        }

        nvkm_falcon_read_dmem(falcon, tail, size, 0, data);
        msgq->position += ALIGN(size, QUEUE_ALIGNMENT);
        return 0;
}

static int
nvkm_falcon_msgq_read(struct nvkm_falcon_msgq *msgq, struct nv_falcon_msg *hdr)
{
        int ret = 0;

        nvkm_falcon_msgq_open(msgq);

        if (nvkm_falcon_msgq_empty(msgq))
                goto close;

        ret = nvkm_falcon_msgq_pop(msgq, hdr, HDR_SIZE);
        if (ret) {
                FLCNQ_ERR(msgq, "failed to read message header");
                goto close;
        }

        if (hdr->size > MSG_BUF_SIZE) {
                FLCNQ_ERR(msgq, "message too big, %d bytes", hdr->size);
                ret = -ENOSPC;
                goto close;
        }

        if (hdr->size > HDR_SIZE) {
                u32 read_size = hdr->size - HDR_SIZE;

                ret = nvkm_falcon_msgq_pop(msgq, (hdr + 1), read_size);
                if (ret) {
                        FLCNQ_ERR(msgq, "failed to read message data");
                        goto close;
                }
        }

        ret = 1;
close:
        nvkm_falcon_msgq_close(msgq, (ret >= 0));
        return ret;
}

static int
nvkm_falcon_msgq_exec(struct nvkm_falcon_msgq *msgq, struct nv_falcon_msg *hdr)
{
        struct nvkm_falcon_qmgr_seq *seq;

        seq = &msgq->qmgr->seq.id[hdr->seq_id];
        if (seq->state != SEQ_STATE_USED && seq->state != SEQ_STATE_CANCELLED) {
                FLCNQ_ERR(msgq, "message for unknown sequence %08x", seq->id);
                return -EINVAL;
        }

        if (seq->state == SEQ_STATE_USED) {
                if (seq->callback)
                        seq->result = seq->callback(seq->priv, hdr);
        }

        if (seq->async) {
                nvkm_falcon_qmgr_seq_release(msgq->qmgr, seq);
                return 0;
        }

        complete_all(&seq->done);
        return 0;
}

void
nvkm_falcon_msgq_recv(struct nvkm_falcon_msgq *msgq)
{
        /*
         * We are invoked from a worker thread, so normally we have plenty of
         * stack space to work with.
         */
        u8 msg_buffer[MSG_BUF_SIZE];
        struct nv_falcon_msg *hdr = (void *)msg_buffer;

        while (nvkm_falcon_msgq_read(msgq, hdr) > 0)
                nvkm_falcon_msgq_exec(msgq, hdr);
}

int
nvkm_falcon_msgq_recv_initmsg(struct nvkm_falcon_msgq *msgq,
                              void *data, u32 size)
{
        struct nvkm_falcon *falcon = msgq->qmgr->falcon;
        struct nv_falcon_msg *hdr = data;
        int ret;

        msgq->head_reg = falcon->func->msgq.head;
        msgq->tail_reg = falcon->func->msgq.tail;
        msgq->offset = nvkm_falcon_rd32(falcon, falcon->func->msgq.tail);

        nvkm_falcon_msgq_open(msgq);
        ret = nvkm_falcon_msgq_pop(msgq, data, size);
        if (ret == 0 && hdr->size != size) {
                FLCN_ERR(falcon, "unexpected init message size %d vs %d",
                         hdr->size, size);
                ret = -EINVAL;
        }
        nvkm_falcon_msgq_close(msgq, ret == 0);
        return ret;
}

void
nvkm_falcon_msgq_init(struct nvkm_falcon_msgq *msgq,
                      u32 index, u32 offset, u32 size)
{
        const struct nvkm_falcon_func *func = msgq->qmgr->falcon->func;

        msgq->head_reg = func->msgq.head + index * func->msgq.stride;
        msgq->tail_reg = func->msgq.tail + index * func->msgq.stride;
        msgq->offset = offset;

        FLCNQ_DBG(msgq, "initialised @ index %d offset 0x%08x size 0x%08x",
                  index, msgq->offset, size);
}

void
nvkm_falcon_msgq_del(struct nvkm_falcon_msgq **pmsgq)
{
        struct nvkm_falcon_msgq *msgq = *pmsgq;
        if (msgq) {
                kfree(*pmsgq);
                *pmsgq = NULL;
        }
}

int
nvkm_falcon_msgq_new(struct nvkm_falcon_qmgr *qmgr, const char *name,
                     struct nvkm_falcon_msgq **pmsgq)
{
        struct nvkm_falcon_msgq *msgq = *pmsgq;

        if (!(msgq = *pmsgq = kzalloc(sizeof(*msgq), GFP_KERNEL)))
                return -ENOMEM;

        msgq->qmgr = qmgr;
        msgq->name = name;
        mutex_init(&msgq->mutex);
        return 0;
}