/*
 * mtu3_qmu.c - Queue Management Unit driver for device controller
 *
 * Copyright (C) 2016 MediaTek Inc.
 *
 * Author: Chunfeng Yun <chunfeng.yun@mediatek.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 *
 */

/*
 * Queue Management Unit (QMU) is designed to unload SW effort
 * to serve DMA interrupts.
 * By preparing General Purpose Descriptor (GPD) and Buffer Descriptor (BD),
 * SW links data buffers and triggers QMU to send / receive data to
 * host / from device at a time.
 * And now only GPD is supported.
 *
 * For more detailed information, please refer to QMU Programming Guide
 */

#include <linux/dmapool.h>
#include <linux/iopoll.h>

#include "mtu3.h"

#define QMU_CHECKSUM_LEN        16

#define GPD_FLAGS_HWO   BIT(0)
#define GPD_FLAGS_BDP   BIT(1)
#define GPD_FLAGS_BPS   BIT(2)
#define GPD_FLAGS_IOC   BIT(7)

#define GPD_EXT_FLAG_ZLP        BIT(5)


static struct qmu_gpd *gpd_dma_to_virt(struct mtu3_gpd_ring *ring,
                dma_addr_t dma_addr)
{
        dma_addr_t dma_base = ring->dma;
        struct qmu_gpd *gpd_head = ring->start;
        u32 offset = (dma_addr - dma_base) / sizeof(*gpd_head);

        if (offset >= MAX_GPD_NUM)
                return NULL;

        return gpd_head + offset;
}

static dma_addr_t gpd_virt_to_dma(struct mtu3_gpd_ring *ring,
                struct qmu_gpd *gpd)
{
        dma_addr_t dma_base = ring->dma;
        struct qmu_gpd *gpd_head = ring->start;
        u32 offset;

        offset = gpd - gpd_head;
        if (offset >= MAX_GPD_NUM)
                return 0;

        return dma_base + (offset * sizeof(*gpd));
}

static void gpd_ring_init(struct mtu3_gpd_ring *ring, struct qmu_gpd *gpd)
{
        ring->start = gpd;
        ring->enqueue = gpd;
        ring->dequeue = gpd;
        ring->end = gpd + MAX_GPD_NUM - 1;
}

static void reset_gpd_list(struct mtu3_ep *mep)
{
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;
        struct qmu_gpd *gpd = ring->start;

        if (gpd) {
                gpd->flag &= ~GPD_FLAGS_HWO;
                gpd_ring_init(ring, gpd);
        }
}

int mtu3_gpd_ring_alloc(struct mtu3_ep *mep)
{
        struct qmu_gpd *gpd;
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;

        /* software own all gpds as default */
        gpd = dma_pool_zalloc(mep->mtu->qmu_gpd_pool, GFP_ATOMIC, &ring->dma);
        if (gpd == NULL)
                return -ENOMEM;

        gpd_ring_init(ring, gpd);

        return 0;
}

void mtu3_gpd_ring_free(struct mtu3_ep *mep)
{
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;

        dma_pool_free(mep->mtu->qmu_gpd_pool,
                        ring->start, ring->dma);
        memset(ring, 0, sizeof(*ring));
}

/*
 * calculate check sum of a gpd or bd
 * add "noinline" and "mb" to prevent wrong calculation
 */
static noinline u8 qmu_calc_checksum(u8 *data)
{
        u8 chksum = 0;
        int i;

        data[1] = 0x0;  /* set checksum to 0 */

        mb();   /* ensure the gpd/bd is really up-to-date */
        for (i = 0; i < QMU_CHECKSUM_LEN; i++)
                chksum += data[i];

        /* Default: HWO=1, @flag[bit0] */
        chksum += 1;

        return 0xFF - chksum;
}

void mtu3_qmu_resume(struct mtu3_ep *mep)
{
        struct mtu3 *mtu = mep->mtu;
        void __iomem *mbase = mtu->mac_base;
        int epnum = mep->epnum;
        u32 offset;

        offset = mep->is_in ? USB_QMU_TQCSR(epnum) : USB_QMU_RQCSR(epnum);

        mtu3_writel(mbase, offset, QMU_Q_RESUME);
        if (!(mtu3_readl(mbase, offset) & QMU_Q_ACTIVE))
                mtu3_writel(mbase, offset, QMU_Q_RESUME);
}

static struct qmu_gpd *advance_enq_gpd(struct mtu3_gpd_ring *ring)
{
        if (ring->enqueue < ring->end)
                ring->enqueue++;
        else
                ring->enqueue = ring->start;

        return ring->enqueue;
}

static struct qmu_gpd *advance_deq_gpd(struct mtu3_gpd_ring *ring)
{
        if (ring->dequeue < ring->end)
                ring->dequeue++;
        else
                ring->dequeue = ring->start;

        return ring->dequeue;
}

/* check if a ring is emtpy */
static int gpd_ring_empty(struct mtu3_gpd_ring *ring)
{
        struct qmu_gpd *enq = ring->enqueue;
        struct qmu_gpd *next;

        if (ring->enqueue < ring->end)
                next = enq + 1;
        else
                next = ring->start;

        /* one gpd is reserved to simplify gpd preparation */
        return next == ring->dequeue;
}

int mtu3_prepare_transfer(struct mtu3_ep *mep)
{
        return gpd_ring_empty(&mep->gpd_ring);
}

static int mtu3_prepare_tx_gpd(struct mtu3_ep *mep, struct mtu3_request *mreq)
{
        struct qmu_gpd *enq;
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;
        struct qmu_gpd *gpd = ring->enqueue;
        struct usb_request *req = &mreq->request;

        /* set all fields to zero as default value */
        memset(gpd, 0, sizeof(*gpd));

        gpd->buffer = cpu_to_le32((u32)req->dma);
        gpd->buf_len = cpu_to_le16(req->length);
        gpd->flag |= GPD_FLAGS_IOC;

        /* get the next GPD */
        enq = advance_enq_gpd(ring);
        dev_dbg(mep->mtu->dev, "TX-EP%d queue gpd=%p, enq=%p\n",
                mep->epnum, gpd, enq);

        enq->flag &= ~GPD_FLAGS_HWO;
        gpd->next_gpd = cpu_to_le32((u32)gpd_virt_to_dma(ring, enq));

        if (req->zero)
                gpd->ext_flag |= GPD_EXT_FLAG_ZLP;

        gpd->chksum = qmu_calc_checksum((u8 *)gpd);
        gpd->flag |= GPD_FLAGS_HWO;

        mreq->gpd = gpd;

        return 0;
}

static int mtu3_prepare_rx_gpd(struct mtu3_ep *mep, struct mtu3_request *mreq)
{
        struct qmu_gpd *enq;
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;
        struct qmu_gpd *gpd = ring->enqueue;
        struct usb_request *req = &mreq->request;

        /* set all fields to zero as default value */
        memset(gpd, 0, sizeof(*gpd));

        gpd->buffer = cpu_to_le32((u32)req->dma);
        gpd->data_buf_len = cpu_to_le16(req->length);
        gpd->flag |= GPD_FLAGS_IOC;

        /* get the next GPD */
        enq = advance_enq_gpd(ring);
        dev_dbg(mep->mtu->dev, "RX-EP%d queue gpd=%p, enq=%p\n",
                mep->epnum, gpd, enq);

        enq->flag &= ~GPD_FLAGS_HWO;
        gpd->next_gpd = cpu_to_le32((u32)gpd_virt_to_dma(ring, enq));
        gpd->chksum = qmu_calc_checksum((u8 *)gpd);
        gpd->flag |= GPD_FLAGS_HWO;

        mreq->gpd = gpd;

        return 0;
}

void mtu3_insert_gpd(struct mtu3_ep *mep, struct mtu3_request *mreq)
{

        if (mep->is_in)
                mtu3_prepare_tx_gpd(mep, mreq);
        else
                mtu3_prepare_rx_gpd(mep, mreq);
}

int mtu3_qmu_start(struct mtu3_ep *mep)
{
        struct mtu3 *mtu = mep->mtu;
        void __iomem *mbase = mtu->mac_base;
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;
        u8 epnum = mep->epnum;

        if (mep->is_in) {
                /* set QMU start address */
                mtu3_writel(mbase, USB_QMU_TQSAR(mep->epnum), ring->dma);
                mtu3_setbits(mbase, MU3D_EP_TXCR0(mep->epnum), TX_DMAREQEN);
                mtu3_setbits(mbase, U3D_QCR0, QMU_TX_CS_EN(epnum));
                /* send zero length packet according to ZLP flag in GPD */
                mtu3_setbits(mbase, U3D_QCR1, QMU_TX_ZLP(epnum));
                mtu3_writel(mbase, U3D_TQERRIESR0,
                                QMU_TX_LEN_ERR(epnum) | QMU_TX_CS_ERR(epnum));

                if (mtu3_readl(mbase, USB_QMU_TQCSR(epnum)) & QMU_Q_ACTIVE) {
                        dev_warn(mtu->dev, "Tx %d Active Now!\n", epnum);
                        return 0;
                }
                mtu3_writel(mbase, USB_QMU_TQCSR(epnum), QMU_Q_START);

        } else {
                mtu3_writel(mbase, USB_QMU_RQSAR(mep->epnum), ring->dma);
                mtu3_setbits(mbase, MU3D_EP_RXCR0(mep->epnum), RX_DMAREQEN);
                mtu3_setbits(mbase, U3D_QCR0, QMU_RX_CS_EN(epnum));
                /* don't expect ZLP */
                mtu3_clrbits(mbase, U3D_QCR3, QMU_RX_ZLP(epnum));
                /* move to next GPD when receive ZLP */
                mtu3_setbits(mbase, U3D_QCR3, QMU_RX_COZ(epnum));
                mtu3_writel(mbase, U3D_RQERRIESR0,
                                QMU_RX_LEN_ERR(epnum) | QMU_RX_CS_ERR(epnum));
                mtu3_writel(mbase, U3D_RQERRIESR1, QMU_RX_ZLP_ERR(epnum));

                if (mtu3_readl(mbase, USB_QMU_RQCSR(epnum)) & QMU_Q_ACTIVE) {
                        dev_warn(mtu->dev, "Rx %d Active Now!\n", epnum);
                        return 0;
                }
                mtu3_writel(mbase, USB_QMU_RQCSR(epnum), QMU_Q_START);
        }

        return 0;
}

/* may called in atomic context */
void mtu3_qmu_stop(struct mtu3_ep *mep)
{
        struct mtu3 *mtu = mep->mtu;
        void __iomem *mbase = mtu->mac_base;
        int epnum = mep->epnum;
        u32 value = 0;
        u32 qcsr;
        int ret;

        qcsr = mep->is_in ? USB_QMU_TQCSR(epnum) : USB_QMU_RQCSR(epnum);

        if (!(mtu3_readl(mbase, qcsr) & QMU_Q_ACTIVE)) {
                dev_dbg(mtu->dev, "%s's qmu is inactive now!\n", mep->name);
                return;
        }
        mtu3_writel(mbase, qcsr, QMU_Q_STOP);

        ret = readl_poll_timeout_atomic(mbase + qcsr, value,
                        !(value & QMU_Q_ACTIVE), 1, 1000);
        if (ret) {
                dev_err(mtu->dev, "stop %s's qmu failed\n", mep->name);
                return;
        }

        dev_dbg(mtu->dev, "%s's qmu stop now!\n", mep->name);
}

void mtu3_qmu_flush(struct mtu3_ep *mep)
{

        dev_dbg(mep->mtu->dev, "%s flush QMU %s\n", __func__,
                ((mep->is_in) ? "TX" : "RX"));

        /*Stop QMU */
        mtu3_qmu_stop(mep);
        reset_gpd_list(mep);
}

/*
 * QMU can't transfer zero length packet directly (a hardware limit
 * on old SoCs), so when needs to send ZLP, we intentionally trigger
 * a length error interrupt, and in the ISR sends a ZLP by BMU.
 */
static void qmu_tx_zlp_error_handler(struct mtu3 *mtu, u8 epnum)
{
        struct mtu3_ep *mep = mtu->in_eps + epnum;
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;
        void __iomem *mbase = mtu->mac_base;
        struct qmu_gpd *gpd_current = NULL;
        dma_addr_t gpd_dma = mtu3_readl(mbase, USB_QMU_TQCPR(epnum));
        struct usb_request *req = NULL;
        struct mtu3_request *mreq;
        u32 txcsr = 0;
        int ret;

        mreq = next_request(mep);
        if (mreq && mreq->request.length == 0)
                req = &mreq->request;
        else
                return;

        gpd_current = gpd_dma_to_virt(ring, gpd_dma);

        if (le16_to_cpu(gpd_current->buf_len) != 0) {
                dev_err(mtu->dev, "TX EP%d buffer length error(!=0)\n", epnum);
                return;
        }

        dev_dbg(mtu->dev, "%s send ZLP for req=%p\n", __func__, mreq);

        mtu3_clrbits(mbase, MU3D_EP_TXCR0(mep->epnum), TX_DMAREQEN);

        ret = readl_poll_timeout_atomic(mbase + MU3D_EP_TXCR0(mep->epnum),
                        txcsr, !(txcsr & TX_FIFOFULL), 1, 1000);
        if (ret) {
                dev_err(mtu->dev, "%s wait for fifo empty fail\n", __func__);
                return;
        }
        mtu3_setbits(mbase, MU3D_EP_TXCR0(mep->epnum), TX_TXPKTRDY);

        /* by pass the current GDP */
        gpd_current->flag |= GPD_FLAGS_BPS;
        gpd_current->chksum = qmu_calc_checksum((u8 *)gpd_current);
        gpd_current->flag |= GPD_FLAGS_HWO;

        /*enable DMAREQEN, switch back to QMU mode */
        mtu3_setbits(mbase, MU3D_EP_TXCR0(mep->epnum), TX_DMAREQEN);
        mtu3_qmu_resume(mep);
}

/*
 * NOTE: request list maybe is already empty as following case:
 * queue_tx --> qmu_interrupt(clear interrupt pending, schedule tasklet)-->
 * queue_tx --> process_tasklet(meanwhile, the second one is transferred,
 * tasklet process both of them)-->qmu_interrupt for second one.
 * To avoid upper case, put qmu_done_tx in ISR directly to process it.
 */
static void qmu_done_tx(struct mtu3 *mtu, u8 epnum)
{
        struct mtu3_ep *mep = mtu->in_eps + epnum;
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;
        void __iomem *mbase = mtu->mac_base;
        struct qmu_gpd *gpd = ring->dequeue;
        struct qmu_gpd *gpd_current = NULL;
        dma_addr_t gpd_dma = mtu3_readl(mbase, USB_QMU_TQCPR(epnum));
        struct usb_request *request = NULL;
        struct mtu3_request *mreq;

        /*transfer phy address got from QMU register to virtual address */
        gpd_current = gpd_dma_to_virt(ring, gpd_dma);

        dev_dbg(mtu->dev, "%s EP%d, last=%p, current=%p, enq=%p\n",
                __func__, epnum, gpd, gpd_current, ring->enqueue);

        while (gpd != gpd_current && !(gpd->flag & GPD_FLAGS_HWO)) {

                mreq = next_request(mep);

                if (mreq == NULL || mreq->gpd != gpd) {
                        dev_err(mtu->dev, "no correct TX req is found\n");
                        break;
                }

                request = &mreq->request;
                request->actual = le16_to_cpu(gpd->buf_len);
                mtu3_req_complete(mep, request, 0);

                gpd = advance_deq_gpd(ring);
        }

        dev_dbg(mtu->dev, "%s EP%d, deq=%p, enq=%p, complete\n",
                __func__, epnum, ring->dequeue, ring->enqueue);

}

static void qmu_done_rx(struct mtu3 *mtu, u8 epnum)
{
        struct mtu3_ep *mep = mtu->out_eps + epnum;
        struct mtu3_gpd_ring *ring = &mep->gpd_ring;
        void __iomem *mbase = mtu->mac_base;
        struct qmu_gpd *gpd = ring->dequeue;
        struct qmu_gpd *gpd_current = NULL;
        dma_addr_t gpd_dma = mtu3_readl(mbase, USB_QMU_RQCPR(epnum));
        struct usb_request *req = NULL;
        struct mtu3_request *mreq;

        gpd_current = gpd_dma_to_virt(ring, gpd_dma);

        dev_dbg(mtu->dev, "%s EP%d, last=%p, current=%p, enq=%p\n",
                __func__, epnum, gpd, gpd_current, ring->enqueue);

        while (gpd != gpd_current && !(gpd->flag & GPD_FLAGS_HWO)) {

                mreq = next_request(mep);

                if (mreq == NULL || mreq->gpd != gpd) {
                        dev_err(mtu->dev, "no correct RX req is found\n");
                        break;
                }
                req = &mreq->request;

                req->actual = le16_to_cpu(gpd->buf_len);
                mtu3_req_complete(mep, req, 0);

                gpd = advance_deq_gpd(ring);
        }

        dev_dbg(mtu->dev, "%s EP%d, deq=%p, enq=%p, complete\n",
                __func__, epnum, ring->dequeue, ring->enqueue);
}

static void qmu_done_isr(struct mtu3 *mtu, u32 done_status)
{
        int i;

        for (i = 1; i < mtu->num_eps; i++) {
                if (done_status & QMU_RX_DONE_INT(i))
                        qmu_done_rx(mtu, i);
                if (done_status & QMU_TX_DONE_INT(i))
                        qmu_done_tx(mtu, i);
        }
}

static void qmu_exception_isr(struct mtu3 *mtu, u32 qmu_status)
{
        void __iomem *mbase = mtu->mac_base;
        u32 errval;
        int i;

        if ((qmu_status & RXQ_CSERR_INT) || (qmu_status & RXQ_LENERR_INT)) {
                errval = mtu3_readl(mbase, U3D_RQERRIR0);
                for (i = 1; i < mtu->num_eps; i++) {
                        if (errval & QMU_RX_CS_ERR(i))
                                dev_err(mtu->dev, "Rx %d CS error!\n", i);

                        if (errval & QMU_RX_LEN_ERR(i))
                                dev_err(mtu->dev, "RX %d Length error\n", i);
                }
                mtu3_writel(mbase, U3D_RQERRIR0, errval);
        }

        if (qmu_status & RXQ_ZLPERR_INT) {
                errval = mtu3_readl(mbase, U3D_RQERRIR1);
                for (i = 1; i < mtu->num_eps; i++) {
                        if (errval & QMU_RX_ZLP_ERR(i))
                                dev_dbg(mtu->dev, "RX EP%d Recv ZLP\n", i);
                }
                mtu3_writel(mbase, U3D_RQERRIR1, errval);
        }

        if ((qmu_status & TXQ_CSERR_INT) || (qmu_status & TXQ_LENERR_INT)) {
                errval = mtu3_readl(mbase, U3D_TQERRIR0);
                for (i = 1; i < mtu->num_eps; i++) {
                        if (errval & QMU_TX_CS_ERR(i))
                                dev_err(mtu->dev, "Tx %d checksum error!\n", i);

                        if (errval & QMU_TX_LEN_ERR(i))
                                qmu_tx_zlp_error_handler(mtu, i);
                }
                mtu3_writel(mbase, U3D_TQERRIR0, errval);
        }
}

irqreturn_t mtu3_qmu_isr(struct mtu3 *mtu)
{
        void __iomem *mbase = mtu->mac_base;
        u32 qmu_status;
        u32 qmu_done_status;

        /* U3D_QISAR1 is read update */
        qmu_status = mtu3_readl(mbase, U3D_QISAR1);
        qmu_status &= mtu3_readl(mbase, U3D_QIER1);

        qmu_done_status = mtu3_readl(mbase, U3D_QISAR0);
        qmu_done_status &= mtu3_readl(mbase, U3D_QIER0);
        mtu3_writel(mbase, U3D_QISAR0, qmu_done_status); /* W1C */
        dev_dbg(mtu->dev, "=== QMUdone[tx=%x, rx=%x] QMUexp[%x] ===\n",
                (qmu_done_status & 0xFFFF), qmu_done_status >> 16,
                qmu_status);

        if (qmu_done_status)
                qmu_done_isr(mtu, qmu_done_status);

        if (qmu_status)
                qmu_exception_isr(mtu, qmu_status);

        return IRQ_HANDLED;
}

int mtu3_qmu_init(struct mtu3 *mtu)
{

        compiletime_assert(QMU_GPD_SIZE == 16, "QMU_GPD size SHOULD be 16B");

        mtu->qmu_gpd_pool = dma_pool_create("QMU_GPD", mtu->dev,
                        QMU_GPD_RING_SIZE, QMU_GPD_SIZE, 0);

        if (!mtu->qmu_gpd_pool)
                return -ENOMEM;

        return 0;
}

void mtu3_qmu_exit(struct mtu3 *mtu)
{
        dma_pool_destroy(mtu->qmu_gpd_pool);
}