/*
 *  Driver for the NXP SAA7164 PCIe bridge
 *
 *  Copyright (c) 2009 Steven Toth <stoth@kernellabs.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "saa7164.h"

/* The message bus to/from the firmware is a ring buffer in PCI address
 * space. Establish the defaults.
 */
int saa7164_bus_setup(struct saa7164_dev *dev)
{
        tmComResBusInfo_t *b    = &dev->bus;

        mutex_init(&b->lock);

        b->Type                 = TYPE_BUS_PCIe;
        b->m_wMaxReqSize        = SAA_DEVICE_MAXREQUESTSIZE;

        b->m_pdwSetRing         = (u8 *)(dev->bmmio +
                ((u32)dev->busdesc.CommandRing));

        b->m_dwSizeSetRing      = SAA_DEVICE_BUFFERBLOCKSIZE;

        b->m_pdwGetRing         = (u8 *)(dev->bmmio +
                ((u32)dev->busdesc.ResponseRing));

        b->m_dwSizeGetRing      = SAA_DEVICE_BUFFERBLOCKSIZE;

        b->m_pdwSetWritePos     = (u32 *)((u8 *)(dev->bmmio +
                ((u32)dev->intfdesc.BARLocation) + (2 * sizeof(u64))));

        b->m_pdwSetReadPos      = (u32 *)((u8 *)b->m_pdwSetWritePos +
                1 * sizeof(u32));

        b->m_pdwGetWritePos     = (u32 *)((u8 *)b->m_pdwSetWritePos +
                2 * sizeof(u32));

        b->m_pdwGetReadPos      = (u32 *)((u8 *)b->m_pdwSetWritePos +
                3 * sizeof(u32));

        return 0;
}

void saa7164_bus_dump(struct saa7164_dev *dev)
{
        tmComResBusInfo_t *b = &dev->bus;

        dprintk(DBGLVL_BUS, "Dumping the bus structure:\n");
        dprintk(DBGLVL_BUS, " .type             = %d\n", b->Type);
        dprintk(DBGLVL_BUS, " .dev->bmmio       = 0x%p\n", dev->bmmio);
        dprintk(DBGLVL_BUS, " .m_wMaxReqSize    = 0x%x\n", b->m_wMaxReqSize);
        dprintk(DBGLVL_BUS, " .m_pdwSetRing     = 0x%p\n", b->m_pdwSetRing);
        dprintk(DBGLVL_BUS, " .m_dwSizeSetRing  = 0x%x\n", b->m_dwSizeSetRing);
        dprintk(DBGLVL_BUS, " .m_pdwGetRing     = 0x%p\n", b->m_pdwGetRing);
        dprintk(DBGLVL_BUS, " .m_dwSizeGetRing  = 0x%x\n", b->m_dwSizeGetRing);

        dprintk(DBGLVL_BUS, " .m_pdwSetWritePos = 0x%p (0x%08x)\n",
                b->m_pdwSetWritePos, *b->m_pdwSetWritePos);

        dprintk(DBGLVL_BUS, " .m_pdwSetReadPos  = 0x%p (0x%08x)\n",
                b->m_pdwSetReadPos, *b->m_pdwSetReadPos);

        dprintk(DBGLVL_BUS, " .m_pdwGetWritePos = 0x%p (0x%08x)\n",
                b->m_pdwGetWritePos, *b->m_pdwGetWritePos);

        dprintk(DBGLVL_BUS, " .m_pdwGetReadPos  = 0x%p (0x%08x)\n",
                b->m_pdwGetReadPos, *b->m_pdwGetReadPos);
}

void saa7164_bus_dumpmsg(struct saa7164_dev *dev, tmComResInfo_t* m, void *buf)
{
        dprintk(DBGLVL_BUS, "Dumping msg structure:\n");
        dprintk(DBGLVL_BUS, " .id               = %d\n",   m->id);
        dprintk(DBGLVL_BUS, " .flags            = 0x%x\n", m->flags);
        dprintk(DBGLVL_BUS, " .size             = 0x%x\n", m->size);
        dprintk(DBGLVL_BUS, " .command          = 0x%x\n", m->command);
        dprintk(DBGLVL_BUS, " .controlselector  = 0x%x\n", m->controlselector);
        dprintk(DBGLVL_BUS, " .seqno            = %d\n",   m->seqno);
        if (buf)
                dprintk(DBGLVL_BUS, " .buffer (ignored)\n");
}

/*
 * Places a command or a response on the bus. The implementation does not
 * know if it is a command or a response it just places the data on the
 * bus depending on the bus information given in the tmComResBusInfo_t
 * structure. If the command or response does not fit into the bus ring
 * buffer it will be refused.
 *
 * Return Value:
 *  SAA_OK     The function executed successfully.
 *  < 0        One or more members are not initialized.
 */
int saa7164_bus_set(struct saa7164_dev *dev, tmComResInfo_t* msg, void *buf)
{
        tmComResBusInfo_t *bus = &dev->bus;
        u32 bytes_to_write, read_distance, timeout, curr_srp, curr_swp;
        u32 new_swp, space_rem;
        int ret = SAA_ERR_BAD_PARAMETER;

        if (!msg) {
                printk(KERN_ERR "%s() !msg\n", __func__);
                return SAA_ERR_BAD_PARAMETER;
        }

        dprintk(DBGLVL_BUS, "%s()\n", __func__);

        msg->size = cpu_to_le16(msg->size);
        msg->command = cpu_to_le16(msg->command);
        msg->controlselector = cpu_to_le16(msg->controlselector);

        if (msg->size > dev->bus.m_wMaxReqSize) {
                printk(KERN_ERR "%s() Exceeded dev->bus.m_wMaxReqSize\n",
                        __func__);
                return SAA_ERR_BAD_PARAMETER;
        }

        if ((msg->size > 0) && (buf == 0)) {
                printk(KERN_ERR "%s() Missing message buffer\n", __func__);
                return SAA_ERR_BAD_PARAMETER;
        }

        /* Lock the bus from any other access */
        mutex_lock(&bus->lock);

        bytes_to_write = sizeof(*msg) + msg->size;
        read_distance = 0;
        timeout = SAA_BUS_TIMEOUT;
        curr_srp = le32_to_cpu(*bus->m_pdwSetReadPos);
        curr_swp = le32_to_cpu(*bus->m_pdwSetWritePos);

        /* Deal with ring wrapping issues */
        if (curr_srp > curr_swp)
                /* The ring has not wrapped yet */
                read_distance = curr_srp - curr_swp;
        else
                /* Deal with the wrapped ring */
                read_distance = (curr_srp + bus->m_dwSizeSetRing) - curr_swp;

        dprintk(DBGLVL_BUS, "%s() bytes_to_write = %d\n", __func__,
                bytes_to_write);

        dprintk(DBGLVL_BUS, "%s() read_distance = %d\n", __func__,
                read_distance);

        dprintk(DBGLVL_BUS, "%s() curr_srp = %x\n", __func__, curr_srp);
        dprintk(DBGLVL_BUS, "%s() curr_swp = %x\n", __func__, curr_swp);

        /* Process the msg and write the content onto the bus */
        while (bytes_to_write >= read_distance) {

                if (timeout-- == 0) {
                        printk(KERN_ERR "%s() bus timeout\n", __func__);
                        ret = SAA_ERR_NO_RESOURCES;
                        goto out;
                }

                /* TODO: Review this delay, efficient? */
                /* Wait, allowing the hardware fetch time */
                mdelay(1);

                /* Check the space usage again */
                curr_srp = le32_to_cpu(*bus->m_pdwSetReadPos);

                /* Deal with ring wrapping issues */
                if (curr_srp > curr_swp)
                        /* Read didn't wrap around the buffer */
                        read_distance = curr_srp - curr_swp;
                else
                        /* Deal with the wrapped ring */
                        read_distance = (curr_srp + bus->m_dwSizeSetRing) -
                                curr_swp;

        }

        /* Calculate the new write position */
        new_swp = curr_swp + bytes_to_write;

        dprintk(DBGLVL_BUS, "%s() new_swp = %x\n", __func__, new_swp);
        dprintk(DBGLVL_BUS, "%s() bus->m_dwSizeSetRing = %x\n", __func__,
                bus->m_dwSizeSetRing);

        /* Mental Note: line 462 tmmhComResBusPCIe.cpp */

        /* Check if we're going to wrap again */
        if (new_swp > bus->m_dwSizeSetRing) {

                /* Ring wraps */
                new_swp -= bus->m_dwSizeSetRing;

                space_rem = bus->m_dwSizeSetRing - curr_swp;

                dprintk(DBGLVL_BUS, "%s() space_rem = %x\n", __func__,
                        space_rem);

                dprintk(DBGLVL_BUS, "%s() sizeof(*msg) = %d\n", __func__,
                        (u32)sizeof(*msg));

                if (space_rem < sizeof(*msg)) {
                        dprintk(DBGLVL_BUS, "%s() tr4\n", __func__);

                        /* Split the msg into pieces as the ring wraps */
                        memcpy(bus->m_pdwSetRing + curr_swp, msg, space_rem);
                        memcpy(bus->m_pdwSetRing, (u8 *)msg + space_rem,
                                sizeof(*msg) - space_rem);

                        memcpy(bus->m_pdwSetRing + sizeof(*msg) - space_rem,
                                buf, msg->size);

                } else if (space_rem == sizeof(*msg)) {
                        dprintk(DBGLVL_BUS, "%s() tr5\n", __func__);

                        /* Additional data at the beginning of the ring */
                        memcpy(bus->m_pdwSetRing + curr_swp, msg, sizeof(*msg));
                        memcpy(bus->m_pdwSetRing, buf, msg->size);

                } else {
                        /* Additional data wraps around the ring */
                        memcpy(bus->m_pdwSetRing + curr_swp, msg, sizeof(*msg));
                        if (msg->size > 0) {
                                memcpy(bus->m_pdwSetRing + curr_swp +
                                        sizeof(*msg), buf, space_rem -
                                        sizeof(*msg));
                                memcpy(bus->m_pdwSetRing, (u8 *)buf +
                                        space_rem - sizeof(*msg),
                                        bytes_to_write - space_rem);
                        }

                }

        } /* (new_swp > bus->m_dwSizeSetRing) */
        else {
                dprintk(DBGLVL_BUS, "%s() tr6\n", __func__);

                /* The ring buffer doesn't wrap, two simple copies */
                memcpy(bus->m_pdwSetRing + curr_swp, msg, sizeof(*msg));
                memcpy(bus->m_pdwSetRing + curr_swp + sizeof(*msg), buf,
                        msg->size);
        }

        dprintk(DBGLVL_BUS, "%s() new_swp = %x\n", __func__, new_swp);

        /* TODO: Convert all of the direct PCI writes into
         * saa7164_writel/b calls for consistency.
         */

        /* Update the bus write position */
        *bus->m_pdwSetWritePos = cpu_to_le32(new_swp);
        ret = SAA_OK;

out:
        mutex_unlock(&bus->lock);
        return ret;
}

/*
 * Receive a command or a response from the bus. The implementation does not
 * know if it is a command or a response it simply dequeues the data,
 * depending on the bus information given in the tmComResBusInfo_t structure.
 *
 * Return Value:
 *  0          The function executed successfully.
 *  < 0        One or more members are not initialized.
 */
int saa7164_bus_get(struct saa7164_dev *dev, tmComResInfo_t* msg, void *buf,
        int peekonly)
{
        tmComResBusInfo_t *bus = &dev->bus;
        u32 bytes_to_read, write_distance, curr_grp, curr_gwp,
                new_grp, buf_size, space_rem;
        tmComResInfo_t msg_tmp;
        int ret = SAA_ERR_BAD_PARAMETER;

        if (msg == 0)
                return ret;

        if (msg->size > dev->bus.m_wMaxReqSize) {
                printk(KERN_ERR "%s() Exceeded dev->bus.m_wMaxReqSize\n",
                        __func__);
                return ret;
        }

        if ((peekonly == 0) && (msg->size > 0) && (buf == 0)) {
                printk(KERN_ERR
                        "%s() Missing msg buf, size should be %d bytes\n",
                        __func__, msg->size);
                return ret;
        }

        mutex_lock(&bus->lock);

        /* Peek the bus to see if a msg exists, if it's not what we're expecting
         * then return cleanly else read the message from the bus.
         */
        curr_gwp = le32_to_cpu(*bus->m_pdwGetWritePos);
        curr_grp = le32_to_cpu(*bus->m_pdwGetReadPos);

        if (curr_gwp == curr_grp) {
                dprintk(DBGLVL_BUS, "%s() No message on the bus\n", __func__);
                ret = SAA_ERR_EMPTY;
                goto out;
        }

        bytes_to_read = sizeof(*msg);

        /* Calculate write distance to current read position */
        write_distance = 0;
        if (curr_gwp >= curr_grp)
                /* Write doesn't wrap around the ring */
                write_distance = curr_gwp - curr_grp;
        else
                /* Write wraps around the ring */
                write_distance = curr_gwp + bus->m_dwSizeGetRing - curr_grp;

        if (bytes_to_read > write_distance) {
                printk(KERN_ERR "%s() No message/response found\n", __func__);
                ret = SAA_ERR_INVALID_COMMAND;
                goto out;
        }

        /* Calculate the new read position */
        new_grp = curr_grp + bytes_to_read;
        if (new_grp > bus->m_dwSizeGetRing) {

                /* Ring wraps */
                new_grp -= bus->m_dwSizeGetRing;
                space_rem = bus->m_dwSizeGetRing - curr_grp;

                memcpy(&msg_tmp, bus->m_pdwGetRing + curr_grp, space_rem);
                memcpy((u8 *)&msg_tmp + space_rem, bus->m_pdwGetRing,
                        bytes_to_read - space_rem);

        } else {
                /* No wrapping */
                memcpy(&msg_tmp, bus->m_pdwGetRing + curr_grp, bytes_to_read);
        }

        /* No need to update the read positions, because this was a peek */
        /* If the caller specifically want to peek, return */
        if (peekonly) {
                memcpy(msg, &msg_tmp, sizeof(*msg));
                goto peekout;
        }

        /* Check if the command/response matches what is expected */
        if ((msg_tmp.id != msg->id) || (msg_tmp.command != msg->command) ||
                (msg_tmp.controlselector != msg->controlselector) ||
                (msg_tmp.seqno != msg->seqno) || (msg_tmp.size != msg->size)) {

                printk(KERN_ERR "%s() Unexpected msg miss-match\n", __func__);
                saa7164_bus_dumpmsg(dev, msg, buf);
                saa7164_bus_dumpmsg(dev, &msg_tmp, 0);
                ret = SAA_ERR_INVALID_COMMAND;
                goto out;
        }

        /* Get the actual command and response from the bus */
        buf_size = msg->size;

        bytes_to_read = sizeof(*msg) + msg->size;
        /* Calculate write distance to current read position */
        write_distance = 0;
        if (curr_gwp >= curr_grp)
                /* Write doesn't wrap around the ring */
                write_distance = curr_gwp - curr_grp;
        else
                /* Write wraps around the ring */
                write_distance = curr_gwp + bus->m_dwSizeGetRing - curr_grp;

        if (bytes_to_read > write_distance) {
                printk(KERN_ERR "%s() Invalid bus state, missing msg "
                        "or mangled ring, faulty H/W / bad code?\n", __func__);
                ret = SAA_ERR_INVALID_COMMAND;
                goto out;
        }

        /* Calculate the new read position */
        new_grp = curr_grp + bytes_to_read;
        if (new_grp > bus->m_dwSizeGetRing) {

                /* Ring wraps */
                new_grp -= bus->m_dwSizeGetRing;
                space_rem = bus->m_dwSizeGetRing - curr_grp;

                if (space_rem < sizeof(*msg)) {
                        /* msg wraps around the ring */
                        memcpy(msg, bus->m_pdwGetRing + curr_grp, space_rem);
                        memcpy((u8 *)msg + space_rem, bus->m_pdwGetRing,
                                sizeof(*msg) - space_rem);
                        if (buf)
                                memcpy(buf, bus->m_pdwGetRing + sizeof(*msg) -
                                        space_rem, buf_size);

                } else if (space_rem == sizeof(*msg)) {
                        memcpy(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
                        if (buf)
                                memcpy(buf, bus->m_pdwGetRing, buf_size);
                } else {
                        /* Additional data wraps around the ring */
                        memcpy(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
                        if (buf) {
                                memcpy(buf, bus->m_pdwGetRing + curr_grp +
                                        sizeof(*msg), space_rem - sizeof(*msg));
                                memcpy(buf + space_rem - sizeof(*msg),
                                        bus->m_pdwGetRing, bytes_to_read -
                                        space_rem);
                        }

                }

        } else {
                /* No wrapping */
                memcpy(msg, bus->m_pdwGetRing + curr_grp, sizeof(*msg));
                if (buf)
                        memcpy(buf, bus->m_pdwGetRing + curr_grp + sizeof(*msg),
                                buf_size);
        }

        /* Update the read positions, adjusting the ring */
        *bus->m_pdwGetReadPos = cpu_to_le32(new_grp);

peekout:
        msg->size = le16_to_cpu(msg->size);
        msg->command = le16_to_cpu(msg->command);
        msg->controlselector = le16_to_cpu(msg->controlselector);
        ret = SAA_OK;
out:
        mutex_unlock(&bus->lock);
        return ret;
}