/*
 * Copyright 2008-2010 Cisco Systems, Inc.  All rights reserved.
 * Copyright 2007 Nuova Systems, Inc.  All rights reserved.
 *
 * This program is free software; you may redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * 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 AUTHORS OR COPYRIGHT HOLDERS
 * 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 <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/pci.h>
#include <linux/delay.h>
#include <linux/slab.h>

#include "vnic_dev.h"
#include "vnic_rq.h"
#include "enic.h"

static int vnic_rq_alloc_bufs(struct vnic_rq *rq)
{
        struct vnic_rq_buf *buf;
        unsigned int i, j, count = rq->ring.desc_count;
        unsigned int blks = VNIC_RQ_BUF_BLKS_NEEDED(count);

        for (i = 0; i < blks; i++) {
                rq->bufs[i] = kzalloc(VNIC_RQ_BUF_BLK_SZ(count), GFP_ATOMIC);
                if (!rq->bufs[i])
                        return -ENOMEM;
        }

        for (i = 0; i < blks; i++) {
                buf = rq->bufs[i];
                for (j = 0; j < VNIC_RQ_BUF_BLK_ENTRIES(count); j++) {
                        buf->index = i * VNIC_RQ_BUF_BLK_ENTRIES(count) + j;
                        buf->desc = (u8 *)rq->ring.descs +
                                rq->ring.desc_size * buf->index;
                        if (buf->index + 1 == count) {
                                buf->next = rq->bufs[0];
                                break;
                        } else if (j + 1 == VNIC_RQ_BUF_BLK_ENTRIES(count)) {
                                buf->next = rq->bufs[i + 1];
                        } else {
                                buf->next = buf + 1;
                                buf++;
                        }
                }
        }

        rq->to_use = rq->to_clean = rq->bufs[0];

        return 0;
}

void vnic_rq_free(struct vnic_rq *rq)
{
        struct vnic_dev *vdev;
        unsigned int i;

        vdev = rq->vdev;

        vnic_dev_free_desc_ring(vdev, &rq->ring);

        for (i = 0; i < VNIC_RQ_BUF_BLKS_MAX; i++) {
                if (rq->bufs[i]) {
                        kfree(rq->bufs[i]);
                        rq->bufs[i] = NULL;
                }
        }

        rq->ctrl = NULL;
}

int vnic_rq_alloc(struct vnic_dev *vdev, struct vnic_rq *rq, unsigned int index,
        unsigned int desc_count, unsigned int desc_size)
{
        int err;

        rq->index = index;
        rq->vdev = vdev;

        rq->ctrl = vnic_dev_get_res(vdev, RES_TYPE_RQ, index);
        if (!rq->ctrl) {
                vdev_err(vdev, "Failed to hook RQ[%d] resource\n", index);
                return -EINVAL;
        }

        vnic_rq_disable(rq);

        err = vnic_dev_alloc_desc_ring(vdev, &rq->ring, desc_count, desc_size);
        if (err)
                return err;

        err = vnic_rq_alloc_bufs(rq);
        if (err) {
                vnic_rq_free(rq);
                return err;
        }

        return 0;
}

static void vnic_rq_init_start(struct vnic_rq *rq, unsigned int cq_index,
        unsigned int fetch_index, unsigned int posted_index,
        unsigned int error_interrupt_enable,
        unsigned int error_interrupt_offset)
{
        u64 paddr;
        unsigned int count = rq->ring.desc_count;

        paddr = (u64)rq->ring.base_addr | VNIC_PADDR_TARGET;
        writeq(paddr, &rq->ctrl->ring_base);
        iowrite32(count, &rq->ctrl->ring_size);
        iowrite32(cq_index, &rq->ctrl->cq_index);
        iowrite32(error_interrupt_enable, &rq->ctrl->error_interrupt_enable);
        iowrite32(error_interrupt_offset, &rq->ctrl->error_interrupt_offset);
        iowrite32(0, &rq->ctrl->dropped_packet_count);
        iowrite32(0, &rq->ctrl->error_status);
        iowrite32(fetch_index, &rq->ctrl->fetch_index);
        iowrite32(posted_index, &rq->ctrl->posted_index);

        rq->to_use = rq->to_clean =
                &rq->bufs[fetch_index / VNIC_RQ_BUF_BLK_ENTRIES(count)]
                        [fetch_index % VNIC_RQ_BUF_BLK_ENTRIES(count)];
}

void vnic_rq_init(struct vnic_rq *rq, unsigned int cq_index,
        unsigned int error_interrupt_enable,
        unsigned int error_interrupt_offset)
{
        u32 fetch_index = 0;

        /* Use current fetch_index as the ring starting point */
        fetch_index = ioread32(&rq->ctrl->fetch_index);

        if (fetch_index == 0xFFFFFFFF) { /* check for hardware gone  */
                /* Hardware surprise removal: reset fetch_index */
                fetch_index = 0;
        }

        vnic_rq_init_start(rq, cq_index,
                fetch_index, fetch_index,
                error_interrupt_enable,
                error_interrupt_offset);
}

unsigned int vnic_rq_error_status(struct vnic_rq *rq)
{
        return ioread32(&rq->ctrl->error_status);
}

void vnic_rq_enable(struct vnic_rq *rq)
{
        iowrite32(1, &rq->ctrl->enable);
}

int vnic_rq_disable(struct vnic_rq *rq)
{
        unsigned int wait;
        struct vnic_dev *vdev = rq->vdev;
        int i;

        /* Due to a race condition with clearing RQ "mini-cache" in hw, we need
         * to disable the RQ twice to guarantee that stale descriptors are not
         * used when this RQ is re-enabled.
         */
        for (i = 0; i < 2; i++) {
                iowrite32(0, &rq->ctrl->enable);

                /* Wait for HW to ACK disable request */
                for (wait = 20000; wait > 0; wait--)
                        if (!ioread32(&rq->ctrl->running))
                                break;
                if (!wait) {
                        vdev_neterr(vdev, "Failed to disable RQ[%d]\n",
                                    rq->index);

                        return -ETIMEDOUT;
                }
        }

        return 0;
}

void vnic_rq_clean(struct vnic_rq *rq,
        void (*buf_clean)(struct vnic_rq *rq, struct vnic_rq_buf *buf))
{
        struct vnic_rq_buf *buf;
        u32 fetch_index;
        unsigned int count = rq->ring.desc_count;
        int i;

        buf = rq->to_clean;

        for (i = 0; i < rq->ring.desc_count; i++) {
                (*buf_clean)(rq, buf);
                buf = buf->next;
        }
        rq->ring.desc_avail = rq->ring.desc_count - 1;

        /* Use current fetch_index as the ring starting point */
        fetch_index = ioread32(&rq->ctrl->fetch_index);

        if (fetch_index == 0xFFFFFFFF) { /* check for hardware gone  */
                /* Hardware surprise removal: reset fetch_index */
                fetch_index = 0;
        }
        rq->to_use = rq->to_clean =
                &rq->bufs[fetch_index / VNIC_RQ_BUF_BLK_ENTRIES(count)]
                        [fetch_index % VNIC_RQ_BUF_BLK_ENTRIES(count)];
        iowrite32(fetch_index, &rq->ctrl->posted_index);

        /* Anytime we write fetch_index, we need to re-write 0 to rq->enable
         * to re-sync internal VIC state.
         */
        iowrite32(0, &rq->ctrl->enable);

        vnic_dev_clear_desc_ring(&rq->ring);
}