// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2015 MediaTek Inc.
 * Author:
 *  Zhigang.Wei <zhigang.wei@mediatek.com>
 *  Chunfeng.Yun <chunfeng.yun@mediatek.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>

#include "xhci.h"
#include "xhci-mtk.h"

#define SSP_BW_BOUNDARY 130000
#define SS_BW_BOUNDARY  51000
/* table 5-5. High-speed Isoc Transaction Limits in usb_20 spec */
#define HS_BW_BOUNDARY  6144
/* usb2 spec section11.18.1: at most 188 FS bytes per microframe */
#define FS_PAYLOAD_MAX 188
#define LS_PAYLOAD_MAX 18
/* section 11.18.1, per fs frame */
#define FS_BW_BOUNDARY  1157
#define LS_BW_BOUNDARY  144

/*
 * max number of microframes for split transfer, assume extra-cs budget is 0
 * for fs isoc in : 1 ss + 1 idle + 6 cs (roundup(1023/188))
 */
#define TT_MICROFRAMES_MAX      8
/* offset from SS for fs/ls isoc/intr ep (ss + idle) */
#define CS_OFFSET       2

#define DBG_BUF_EN      64

/* schedule error type */
#define ESCH_SS_Y6              1001
#define ESCH_SS_OVERLAP         1002
#define ESCH_CS_OVERFLOW        1003
#define ESCH_BW_OVERFLOW        1004
#define ESCH_FIXME              1005

/* mtk scheduler bitmasks */
#define EP_BPKTS(p)     ((p) & 0x7f)
#define EP_BCSCOUNT(p)  (((p) & 0x7) << 8)
#define EP_BBM(p)       ((p) << 11)
#define EP_BOFFSET(p)   ((p) & 0x3fff)
#define EP_BREPEAT(p)   (((p) & 0x7fff) << 16)

static char *sch_error_string(int err_num)
{
        switch (err_num) {
        case ESCH_SS_Y6:
                return "Can't schedule Start-Split in Y6";
        case ESCH_SS_OVERLAP:
                return "Can't find a suitable Start-Split location";
        case ESCH_CS_OVERFLOW:
                return "The last Complete-Split is greater than 7";
        case ESCH_BW_OVERFLOW:
                return "Bandwidth exceeds the maximum limit";
        case ESCH_FIXME:
                return "FIXME, to be resolved";
        default:
                return "Unknown";
        }
}

static int is_fs_or_ls(enum usb_device_speed speed)
{
        return speed == USB_SPEED_FULL || speed == USB_SPEED_LOW;
}

static const char *
decode_ep(struct usb_host_endpoint *ep, enum usb_device_speed speed)
{
        static char buf[DBG_BUF_EN];
        struct usb_endpoint_descriptor *epd = &ep->desc;
        unsigned int interval;
        const char *unit;

        interval = usb_decode_interval(epd, speed);
        if (interval % 1000) {
                unit = "us";
        } else {
                unit = "ms";
                interval /= 1000;
        }

        snprintf(buf, DBG_BUF_EN, "%s ep%d%s %s, mpkt:%d, interval:%d/%d%s",
                 usb_speed_string(speed), usb_endpoint_num(epd),
                 usb_endpoint_dir_in(epd) ? "in" : "out",
                 usb_ep_type_string(usb_endpoint_type(epd)),
                 usb_endpoint_maxp(epd), epd->bInterval, interval, unit);

        return buf;
}

static u32 get_bw_boundary(enum usb_device_speed speed)
{
        u32 boundary;

        switch (speed) {
        case USB_SPEED_SUPER_PLUS:
                boundary = SSP_BW_BOUNDARY;
                break;
        case USB_SPEED_SUPER:
                boundary = SS_BW_BOUNDARY;
                break;
        default:
                boundary = HS_BW_BOUNDARY;
                break;
        }

        return boundary;
}

/*
* get the bandwidth domain which @ep belongs to.
*
* the bandwidth domain array is saved to @sch_array of struct xhci_hcd_mtk,
* each HS root port is treated as a single bandwidth domain,
* but each SS root port is treated as two bandwidth domains, one for IN eps,
* one for OUT eps.
*/
static struct mu3h_sch_bw_info *
get_bw_info(struct xhci_hcd_mtk *mtk, struct usb_device *udev,
            struct usb_host_endpoint *ep)
{
        struct xhci_hcd *xhci = hcd_to_xhci(mtk->hcd);
        struct xhci_virt_device *virt_dev;
        int bw_index;

        virt_dev = xhci->devs[udev->slot_id];
        if (!virt_dev->rhub_port) {
                WARN_ONCE(1, "%s invalid rhub port\n", dev_name(&udev->dev));
                return NULL;
        }

        if (udev->speed >= USB_SPEED_SUPER) {
                if (usb_endpoint_dir_out(&ep->desc))
                        bw_index = (virt_dev->rhub_port->hw_portnum) * 2;
                else
                        bw_index = (virt_dev->rhub_port->hw_portnum) * 2 + 1;
        } else {
                /* add one more for each SS port */
                bw_index = virt_dev->rhub_port->hw_portnum + xhci->usb3_rhub.num_ports;
        }

        return &mtk->sch_array[bw_index];
}

static u32 get_esit(struct xhci_ep_ctx *ep_ctx)
{
        u32 esit;

        esit = 1 << CTX_TO_EP_INTERVAL(le32_to_cpu(ep_ctx->ep_info));
        if (esit > XHCI_MTK_MAX_ESIT)
                esit = XHCI_MTK_MAX_ESIT;

        return esit;
}

static struct mu3h_sch_tt *find_tt(struct usb_device *udev)
{
        struct usb_tt *utt = udev->tt;
        struct mu3h_sch_tt *tt, **tt_index, **ptt;
        bool allocated_index = false;

        if (!utt)
                return NULL;    /* Not below a TT */

        /*
         * Find/create our data structure.
         * For hubs with a single TT, we get it directly.
         * For hubs with multiple TTs, there's an extra level of pointers.
         */
        tt_index = NULL;
        if (utt->multi) {
                tt_index = utt->hcpriv;
                if (!tt_index) {        /* Create the index array */
                        tt_index = kzalloc_objs(*tt_index, utt->hub->maxchild);
                        if (!tt_index)
                                return ERR_PTR(-ENOMEM);
                        utt->hcpriv = tt_index;
                        allocated_index = true;
                }
                ptt = &tt_index[udev->ttport - 1];
        } else {
                ptt = (struct mu3h_sch_tt **) &utt->hcpriv;
        }

        tt = *ptt;
        if (!tt) {      /* Create the mu3h_sch_tt */
                tt = kzalloc_obj(*tt);
                if (!tt) {
                        if (allocated_index) {
                                utt->hcpriv = NULL;
                                kfree(tt_index);
                        }
                        return ERR_PTR(-ENOMEM);
                }
                INIT_LIST_HEAD(&tt->ep_list);
                *ptt = tt;
        }

        return tt;
}

/* Release the TT above udev, if it's not in use */
static void drop_tt(struct usb_device *udev)
{
        struct usb_tt *utt = udev->tt;
        struct mu3h_sch_tt *tt, **tt_index, **ptt;
        int i, cnt;

        if (!utt || !utt->hcpriv)
                return;         /* Not below a TT, or never allocated */

        cnt = 0;
        if (utt->multi) {
                tt_index = utt->hcpriv;
                ptt = &tt_index[udev->ttport - 1];
                /*  How many entries are left in tt_index? */
                for (i = 0; i < utt->hub->maxchild; ++i)
                        cnt += !!tt_index[i];
        } else {
                tt_index = NULL;
                ptt = (struct mu3h_sch_tt **)&utt->hcpriv;
        }

        tt = *ptt;
        if (!tt || !list_empty(&tt->ep_list))
                return;         /* never allocated , or still in use*/

        *ptt = NULL;
        kfree(tt);

        if (cnt == 1) {
                utt->hcpriv = NULL;
                kfree(tt_index);
        }
}

static struct mu3h_sch_ep_info *
create_sch_ep(struct xhci_hcd_mtk *mtk, struct usb_device *udev,
              struct usb_host_endpoint *ep, struct xhci_ep_ctx *ep_ctx)
{
        struct mu3h_sch_ep_info *sch_ep;
        struct mu3h_sch_bw_info *bw_info;
        struct mu3h_sch_tt *tt = NULL;
        u32 len;

        bw_info = get_bw_info(mtk, udev, ep);
        if (!bw_info)
                return ERR_PTR(-ENODEV);

        if (is_fs_or_ls(udev->speed))
                len = TT_MICROFRAMES_MAX;
        else if ((udev->speed >= USB_SPEED_SUPER) &&
                 usb_endpoint_xfer_isoc(&ep->desc))
                len = get_esit(ep_ctx);
        else
                len = 1;

        sch_ep = kzalloc_flex(*sch_ep, bw_budget_table, len);
        if (!sch_ep)
                return ERR_PTR(-ENOMEM);

        if (is_fs_or_ls(udev->speed)) {
                tt = find_tt(udev);
                if (IS_ERR(tt)) {
                        kfree(sch_ep);
                        return ERR_PTR(-ENOMEM);
                }
        }

        sch_ep->bw_info = bw_info;
        sch_ep->sch_tt = tt;
        sch_ep->ep = ep;
        sch_ep->speed = udev->speed;
        INIT_LIST_HEAD(&sch_ep->endpoint);
        INIT_LIST_HEAD(&sch_ep->tt_endpoint);
        INIT_HLIST_NODE(&sch_ep->hentry);

        return sch_ep;
}

static void setup_sch_info(struct xhci_ep_ctx *ep_ctx,
                           struct mu3h_sch_ep_info *sch_ep)
{
        u32 ep_type;
        u32 maxpkt;
        u32 max_burst;
        u32 mult;
        u32 esit_pkts;
        u32 max_esit_payload;
        u32 bw_per_microframe;
        u32 *bwb_table;
        int i;

        bwb_table = sch_ep->bw_budget_table;
        ep_type = CTX_TO_EP_TYPE(le32_to_cpu(ep_ctx->ep_info2));
        maxpkt = MAX_PACKET_DECODED(le32_to_cpu(ep_ctx->ep_info2));
        max_burst = CTX_TO_MAX_BURST(le32_to_cpu(ep_ctx->ep_info2));
        mult = CTX_TO_EP_MULT(le32_to_cpu(ep_ctx->ep_info));
        max_esit_payload =
                (CTX_TO_MAX_ESIT_PAYLOAD_HI(
                        le32_to_cpu(ep_ctx->ep_info)) << 16) |
                 CTX_TO_MAX_ESIT_PAYLOAD(le32_to_cpu(ep_ctx->tx_info));

        sch_ep->esit = get_esit(ep_ctx);
        sch_ep->num_esit = XHCI_MTK_MAX_ESIT / sch_ep->esit;
        sch_ep->ep_type = ep_type;
        sch_ep->maxpkt = maxpkt;
        sch_ep->offset = 0;
        sch_ep->burst_mode = 0;
        sch_ep->repeat = 0;

        if (sch_ep->speed == USB_SPEED_HIGH) {
                sch_ep->cs_count = 0;

                /*
                 * usb_20 spec section5.9
                 * a single microframe is enough for HS synchromous endpoints
                 * in a interval
                 */
                sch_ep->num_budget_microframes = 1;

                /*
                 * xHCI spec section6.2.3.4
                 * @max_burst is the number of additional transactions
                 * opportunities per microframe
                 */
                sch_ep->pkts = max_burst + 1;
                bwb_table[0] = maxpkt * sch_ep->pkts;
        } else if (sch_ep->speed >= USB_SPEED_SUPER) {
                /* usb3_r1 spec section4.4.7 & 4.4.8 */
                sch_ep->cs_count = 0;
                sch_ep->burst_mode = 1;
                /*
                 * some device's (d)wBytesPerInterval is set as 0,
                 * then max_esit_payload is 0, so evaluate esit_pkts from
                 * mult and burst
                 */
                esit_pkts = DIV_ROUND_UP(max_esit_payload, maxpkt);
                if (esit_pkts == 0)
                        esit_pkts = (mult + 1) * (max_burst + 1);

                if (ep_type == INT_IN_EP || ep_type == INT_OUT_EP) {
                        sch_ep->pkts = esit_pkts;
                        sch_ep->num_budget_microframes = 1;
                        bwb_table[0] = maxpkt * sch_ep->pkts;
                }

                if (ep_type == ISOC_IN_EP || ep_type == ISOC_OUT_EP) {

                        if (sch_ep->esit == 1)
                                sch_ep->pkts = esit_pkts;
                        else if (esit_pkts <= sch_ep->esit)
                                sch_ep->pkts = 1;
                        else
                                sch_ep->pkts = roundup_pow_of_two(esit_pkts)
                                        / sch_ep->esit;

                        sch_ep->num_budget_microframes =
                                DIV_ROUND_UP(esit_pkts, sch_ep->pkts);

                        sch_ep->repeat = !!(sch_ep->num_budget_microframes > 1);
                        bw_per_microframe = maxpkt * sch_ep->pkts;

                        for (i = 0; i < sch_ep->num_budget_microframes - 1; i++)
                                bwb_table[i] = bw_per_microframe;

                        /* last one <= bw_per_microframe */
                        bwb_table[i] = maxpkt * esit_pkts - i * bw_per_microframe;
                }
        } else if (is_fs_or_ls(sch_ep->speed)) {
                sch_ep->pkts = 1; /* at most one packet for each microframe */

                /*
                 * @cs_count will be updated to add extra-cs when
                 * check TT for INT_OUT_EP, ISOC/INT_IN_EP type
                 * @maxpkt <= 1023;
                 */
                sch_ep->cs_count = DIV_ROUND_UP(maxpkt, FS_PAYLOAD_MAX);
                sch_ep->num_budget_microframes = sch_ep->cs_count;

                /* init budget table */
                if (ep_type == ISOC_OUT_EP) {
                        for (i = 0; i < sch_ep->cs_count - 1; i++)
                                bwb_table[i] = FS_PAYLOAD_MAX;

                        bwb_table[i] = maxpkt - i * FS_PAYLOAD_MAX;
                } else if (ep_type == INT_OUT_EP) {
                        /* only first one used (maxpkt <= 64), others zero */
                        bwb_table[0] = maxpkt;
                } else { /* INT_IN_EP or ISOC_IN_EP */
                        bwb_table[0] = 0; /* start split */
                        bwb_table[1] = 0; /* idle */
                        /*
                         * @cs_count will be updated according to cs position
                         * (add 1 or 2 extra-cs), but assume only first
                         * @num_budget_microframes elements will be used later,
                         * although in fact it does not (extra-cs budget many receive
                         * some data for IN ep);
                         * @cs_count is 1 for INT_IN_EP (maxpkt <= 64);
                         */
                        for (i = 0; i < sch_ep->cs_count - 1; i++)
                                bwb_table[i + CS_OFFSET] = FS_PAYLOAD_MAX;

                        bwb_table[i + CS_OFFSET] = maxpkt - i * FS_PAYLOAD_MAX;
                        /* ss + idle */
                        sch_ep->num_budget_microframes += CS_OFFSET;
                }
        }
}

/* Get maximum bandwidth when we schedule at offset slot. */
static u32 get_max_bw(struct mu3h_sch_bw_info *sch_bw,
        struct mu3h_sch_ep_info *sch_ep, u32 offset)
{
        u32 max_bw = 0;
        u32 bw;
        int i, j, k;

        for (i = 0; i < sch_ep->num_esit; i++) {
                u32 base = offset + i * sch_ep->esit;

                for (j = 0; j < sch_ep->num_budget_microframes; j++) {
                        k = XHCI_MTK_BW_INDEX(base + j);
                        bw = sch_bw->bus_bw[k] + sch_ep->bw_budget_table[j];
                        if (bw > max_bw)
                                max_bw = bw;
                }
        }
        return max_bw;
}

/*
 * for OUT: get first SS consumed bw;
 * for IN: get first CS consumed bw;
 */
static u16 get_fs_bw(struct mu3h_sch_ep_info *sch_ep, int offset)
{
        struct mu3h_sch_tt *tt = sch_ep->sch_tt;
        u16 fs_bw;

        if (sch_ep->ep_type == ISOC_OUT_EP || sch_ep->ep_type == INT_OUT_EP)
                fs_bw = tt->fs_bus_bw_out[XHCI_MTK_BW_INDEX(offset)];
        else    /* skip ss + idle */
                fs_bw = tt->fs_bus_bw_in[XHCI_MTK_BW_INDEX(offset + CS_OFFSET)];

        return fs_bw;
}

static void update_bus_bw(struct mu3h_sch_bw_info *sch_bw,
        struct mu3h_sch_ep_info *sch_ep, bool used)
{
        u32 base;
        int i, j, k;

        for (i = 0; i < sch_ep->num_esit; i++) {
                base = sch_ep->offset + i * sch_ep->esit;
                for (j = 0; j < sch_ep->num_budget_microframes; j++) {
                        k = XHCI_MTK_BW_INDEX(base + j);
                        if (used)
                                sch_bw->bus_bw[k] += sch_ep->bw_budget_table[j];
                        else
                                sch_bw->bus_bw[k] -= sch_ep->bw_budget_table[j];
                }
        }
}

static int check_ls_budget_microframes(struct mu3h_sch_ep_info *sch_ep, int offset)
{
        struct mu3h_sch_tt *tt = sch_ep->sch_tt;
        int i;

        if (sch_ep->speed != USB_SPEED_LOW)
                return 0;

        if (sch_ep->ep_type == INT_OUT_EP)
                i = XHCI_MTK_BW_INDEX(offset);
        else if (sch_ep->ep_type == INT_IN_EP)
                i = XHCI_MTK_BW_INDEX(offset + CS_OFFSET); /* skip ss + idle */
        else
                return -EINVAL;

        if (tt->ls_bus_bw[i] + sch_ep->maxpkt > LS_PAYLOAD_MAX)
                return -ESCH_BW_OVERFLOW;

        return 0;
}

static int check_fs_budget_microframes(struct mu3h_sch_ep_info *sch_ep, int offset)
{
        struct mu3h_sch_tt *tt = sch_ep->sch_tt;
        u32 tmp;
        int i, k;

        /*
         * for OUT eps, will transfer exactly assigned length of data,
         * so can't allocate more than 188 bytes;
         * but it's not for IN eps, usually it can't receive full
         * 188 bytes in a uframe, if it not assign full 188 bytes,
         * can add another one;
         */
        for (i = 0; i < sch_ep->num_budget_microframes; i++) {
                k = XHCI_MTK_BW_INDEX(offset + i);
                if (sch_ep->ep_type == ISOC_OUT_EP || sch_ep->ep_type == INT_OUT_EP)
                        tmp = tt->fs_bus_bw_out[k] + sch_ep->bw_budget_table[i];
                else /* ep_type : ISOC IN / INTR IN */
                        tmp = tt->fs_bus_bw_in[k];

                if (tmp > FS_PAYLOAD_MAX)
                        return -ESCH_BW_OVERFLOW;
        }

        return 0;
}

static int check_fs_budget_frames(struct mu3h_sch_ep_info *sch_ep, int offset)
{
        struct mu3h_sch_tt *tt = sch_ep->sch_tt;
        u32 head, tail;
        int i, j, k;

        /* bugdet scheduled may cross at most two fs frames */
        j = XHCI_MTK_BW_INDEX(offset) / UFRAMES_PER_FRAME;
        k = XHCI_MTK_BW_INDEX(offset + sch_ep->num_budget_microframes - 1) / UFRAMES_PER_FRAME;

        if (j != k) {
                head = tt->fs_frame_bw[j];
                tail = tt->fs_frame_bw[k];
        } else {
                head = tt->fs_frame_bw[j];
                tail = 0;
        }

        j = roundup(offset, UFRAMES_PER_FRAME);
        for (i = 0; i < sch_ep->num_budget_microframes; i++) {
                if ((offset + i) < j)
                        head += sch_ep->bw_budget_table[i];
                else
                        tail += sch_ep->bw_budget_table[i];
        }

        if (head > FS_BW_BOUNDARY || tail > FS_BW_BOUNDARY)
                return -ESCH_BW_OVERFLOW;

        return 0;
}

static int check_fs_bus_bw(struct mu3h_sch_ep_info *sch_ep, int offset)
{
        int i, base;
        int ret = 0;

        for (i = 0; i < sch_ep->num_esit; i++) {
                base = offset + i * sch_ep->esit;

                ret = check_ls_budget_microframes(sch_ep, base);
                if (ret)
                        goto err;

                ret = check_fs_budget_microframes(sch_ep, base);
                if (ret)
                        goto err;

                ret = check_fs_budget_frames(sch_ep, base);
                if (ret)
                        goto err;
        }

err:
        return ret;
}

static int check_ss_and_cs(struct mu3h_sch_ep_info *sch_ep, u32 offset)
{
        u32 start_ss, last_ss;
        u32 start_cs, last_cs;

        start_ss = offset % UFRAMES_PER_FRAME;

        if (sch_ep->ep_type == ISOC_OUT_EP) {
                last_ss = start_ss + sch_ep->cs_count - 1;

                /*
                 * usb_20 spec section11.18:
                 * must never schedule Start-Split in Y6
                 */
                if (!(start_ss == 7 || last_ss < 6))
                        return -ESCH_SS_Y6;

        } else {
                /* maxpkt <= 1023, cs <= 6 */
                u32 cs_count = DIV_ROUND_UP(sch_ep->maxpkt, FS_PAYLOAD_MAX);

                /*
                 * usb_20 spec section11.18:
                 * must never schedule Start-Split in Y6
                 */
                if (start_ss == 6)
                        return -ESCH_SS_Y6;

                /* one uframe for ss + one uframe for idle */
                start_cs = (start_ss + CS_OFFSET) % UFRAMES_PER_FRAME;
                last_cs = start_cs + cs_count - 1;
                if (last_cs > 7)
                        return -ESCH_CS_OVERFLOW;

                /* add extra-cs */
                cs_count += (last_cs == 7) ? 1 : 2;
                if (cs_count > 7)
                        cs_count = 7; /* HW limit */

                sch_ep->cs_count = cs_count;

        }

        return 0;
}

/*
 * when isoc-out transfers 188 bytes in a uframe, and send isoc/intr's
 * ss token in the uframe, may cause 'bit stuff error' in downstream
 * port;
 * when isoc-out transfer less than 188 bytes in a uframe, shall send
 * isoc-in's ss after isoc-out's ss (but hw can't ensure the sequence,
 * so just avoid overlap).
 */
static int check_isoc_ss_overlap(struct mu3h_sch_ep_info *sch_ep, u32 offset)
{
        struct mu3h_sch_tt *tt = sch_ep->sch_tt;
        int base;
        int i, j, k;

        if (!tt)
                return 0;

        for (i = 0; i < sch_ep->num_esit; i++) {
                base = offset + i * sch_ep->esit;

                if (sch_ep->ep_type == ISOC_OUT_EP) {
                        for (j = 0; j < sch_ep->num_budget_microframes; j++) {
                                k = XHCI_MTK_BW_INDEX(base + j);
                                if (tt->in_ss_cnt[k])
                                        return -ESCH_SS_OVERLAP;
                        }
                } else if (sch_ep->ep_type == ISOC_IN_EP || sch_ep->ep_type == INT_IN_EP) {
                        k = XHCI_MTK_BW_INDEX(base);
                        /* only check IN's ss */
                        if (tt->fs_bus_bw_out[k])
                                return -ESCH_SS_OVERLAP;
                }
        }

        return 0;
}

static int check_sch_tt_budget(struct mu3h_sch_ep_info *sch_ep, u32 offset)
{
        int ret;

        ret = check_ss_and_cs(sch_ep, offset);
        if (ret)
                return ret;

        ret = check_isoc_ss_overlap(sch_ep, offset);
        if (ret)
                return ret;

        return check_fs_bus_bw(sch_ep, offset);
}

/* allocate microframes in the ls/fs frame */
static int alloc_sch_portion_of_frame(struct mu3h_sch_ep_info *sch_ep)
{
        struct mu3h_sch_bw_info *sch_bw = sch_ep->bw_info;
        const u32 bw_boundary = get_bw_boundary(sch_ep->speed);
        u32 bw_max, fs_bw_min;
        u32 offset, offset_min;
        u16 fs_bw;
        int frames;
        int i, j;
        int ret;

        frames = sch_ep->esit / UFRAMES_PER_FRAME;

        for (i = 0; i < UFRAMES_PER_FRAME; i++) {
                fs_bw_min = FS_PAYLOAD_MAX;
                offset_min = XHCI_MTK_MAX_ESIT;

                for (j = 0; j < frames; j++) {
                        offset = (i + j * UFRAMES_PER_FRAME) % sch_ep->esit;

                        ret = check_sch_tt_budget(sch_ep, offset);
                        if (ret)
                                continue;

                        /* check hs bw domain */
                        bw_max = get_max_bw(sch_bw, sch_ep, offset);
                        if (bw_max > bw_boundary) {
                                ret = -ESCH_BW_OVERFLOW;
                                continue;
                        }

                        /* use best-fit between frames */
                        fs_bw = get_fs_bw(sch_ep, offset);
                        if (fs_bw < fs_bw_min) {
                                fs_bw_min = fs_bw;
                                offset_min = offset;
                        }

                        if (!fs_bw_min)
                                break;
                }

                /* use first-fit between microframes in a frame */
                if (offset_min < XHCI_MTK_MAX_ESIT)
                        break;
        }

        if (offset_min == XHCI_MTK_MAX_ESIT)
                return -ESCH_BW_OVERFLOW;

        sch_ep->offset = offset_min;

        return 0;
}

static void update_sch_tt(struct mu3h_sch_ep_info *sch_ep, bool used)
{
        struct mu3h_sch_tt *tt = sch_ep->sch_tt;
        u16 *fs_bus_bw;
        u32 base;
        int i, j, k, f;

        if (sch_ep->ep_type == ISOC_OUT_EP || sch_ep->ep_type == INT_OUT_EP)
                fs_bus_bw = tt->fs_bus_bw_out;
        else
                fs_bus_bw = tt->fs_bus_bw_in;

        for (i = 0; i < sch_ep->num_esit; i++) {
                base = sch_ep->offset + i * sch_ep->esit;

                for (j = 0; j < sch_ep->num_budget_microframes; j++) {
                        k = XHCI_MTK_BW_INDEX(base + j);
                        f = k / UFRAMES_PER_FRAME;
                        if (used) {
                                if (sch_ep->speed == USB_SPEED_LOW)
                                        tt->ls_bus_bw[k] += (u8)sch_ep->bw_budget_table[j];

                                fs_bus_bw[k] += (u16)sch_ep->bw_budget_table[j];
                                tt->fs_frame_bw[f] += (u16)sch_ep->bw_budget_table[j];
                        } else {
                                if (sch_ep->speed == USB_SPEED_LOW)
                                        tt->ls_bus_bw[k] -= (u8)sch_ep->bw_budget_table[j];

                                fs_bus_bw[k] -= (u16)sch_ep->bw_budget_table[j];
                                tt->fs_frame_bw[f] -= (u16)sch_ep->bw_budget_table[j];
                        }
                }

                if (sch_ep->ep_type == ISOC_IN_EP || sch_ep->ep_type == INT_IN_EP) {
                        k = XHCI_MTK_BW_INDEX(base);
                        if (used)
                                tt->in_ss_cnt[k]++;
                        else
                                tt->in_ss_cnt[k]--;
                }
        }

        if (used)
                list_add_tail(&sch_ep->tt_endpoint, &tt->ep_list);
        else
                list_del(&sch_ep->tt_endpoint);
}

static int load_ep_bw(struct mu3h_sch_bw_info *sch_bw,
                      struct mu3h_sch_ep_info *sch_ep, bool loaded)
{
        if (sch_ep->sch_tt)
                update_sch_tt(sch_ep, loaded);

        /* update bus bandwidth info */
        update_bus_bw(sch_bw, sch_ep, loaded);
        sch_ep->allocated = loaded;

        return 0;
}

/* allocate microframes for hs/ss/ssp */
static int alloc_sch_microframes(struct mu3h_sch_ep_info *sch_ep)
{
        struct mu3h_sch_bw_info *sch_bw = sch_ep->bw_info;
        const u32 bw_boundary = get_bw_boundary(sch_ep->speed);
        u32 offset;
        u32 worst_bw;
        u32 min_bw = ~0;
        int min_index = -1;

        /*
         * Search through all possible schedule microframes.
         * and find a microframe where its worst bandwidth is minimum.
         */
        for (offset = 0; offset < sch_ep->esit; offset++) {

                worst_bw = get_max_bw(sch_bw, sch_ep, offset);
                if (worst_bw > bw_boundary)
                        continue;

                if (min_bw > worst_bw) {
                        min_bw = worst_bw;
                        min_index = offset;
                }
        }

        if (min_index < 0)
                return -ESCH_BW_OVERFLOW;

        sch_ep->offset = min_index;

        return 0;
}

static int check_sch_bw(struct mu3h_sch_ep_info *sch_ep)
{
        int ret;

        if (sch_ep->sch_tt)
                ret = alloc_sch_portion_of_frame(sch_ep);
        else
                ret = alloc_sch_microframes(sch_ep);

        if (ret)
                return ret;

        return load_ep_bw(sch_ep->bw_info, sch_ep, true);
}

static void destroy_sch_ep(struct xhci_hcd_mtk *mtk, struct usb_device *udev,
                           struct mu3h_sch_ep_info *sch_ep)
{
        /* only release ep bw check passed by check_sch_bw() */
        if (sch_ep->allocated)
                load_ep_bw(sch_ep->bw_info, sch_ep, false);

        if (sch_ep->sch_tt)
                drop_tt(udev);

        list_del(&sch_ep->endpoint);
        hlist_del(&sch_ep->hentry);
        kfree(sch_ep);
}

static bool need_bw_sch(struct usb_device *udev,
                        struct usb_host_endpoint *ep)
{
        bool has_tt = udev->tt && udev->tt->hub->parent;

        /* only for periodic endpoints */
        if (usb_endpoint_xfer_control(&ep->desc)
                || usb_endpoint_xfer_bulk(&ep->desc))
                return false;

        /*
         * for LS & FS periodic endpoints which its device is not behind
         * a TT are also ignored, root-hub will schedule them directly,
         * but need set @bpkts field of endpoint context to 1.
         */
        if (is_fs_or_ls(udev->speed) && !has_tt)
                return false;

        /* skip endpoint with zero maxpkt */
        if (usb_endpoint_maxp(&ep->desc) == 0)
                return false;

        return true;
}

int xhci_mtk_sch_init(struct xhci_hcd_mtk *mtk)
{
        struct xhci_hcd *xhci = hcd_to_xhci(mtk->hcd);
        struct mu3h_sch_bw_info *sch_array;
        int num_usb_bus;

        /* ss IN and OUT are separated */
        num_usb_bus = xhci->usb3_rhub.num_ports * 2 + xhci->usb2_rhub.num_ports;

        sch_array = kzalloc_objs(*sch_array, num_usb_bus);
        if (sch_array == NULL)
                return -ENOMEM;

        mtk->sch_array = sch_array;

        INIT_LIST_HEAD(&mtk->bw_ep_chk_list);
        hash_init(mtk->sch_ep_hash);

        return 0;
}

void xhci_mtk_sch_exit(struct xhci_hcd_mtk *mtk)
{
        kfree(mtk->sch_array);
}

static int add_ep_quirk(struct usb_hcd *hcd, struct usb_device *udev,
                        struct usb_host_endpoint *ep)
{
        struct xhci_hcd_mtk *mtk = hcd_to_mtk(hcd);
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct xhci_ep_ctx *ep_ctx;
        struct xhci_virt_device *virt_dev;
        struct mu3h_sch_ep_info *sch_ep;
        unsigned int ep_index;

        virt_dev = xhci->devs[udev->slot_id];
        ep_index = xhci_get_endpoint_index(&ep->desc);
        ep_ctx = xhci_get_ep_ctx(xhci, virt_dev->in_ctx, ep_index);

        if (!need_bw_sch(udev, ep)) {
                /*
                 * set @bpkts to 1 if it is LS or FS periodic endpoint, and its
                 * device does not connected through an external HS hub
                 */
                if (usb_endpoint_xfer_int(&ep->desc)
                        || usb_endpoint_xfer_isoc(&ep->desc))
                        ep_ctx->reserved[0] = cpu_to_le32(EP_BPKTS(1));

                return 0;
        }

        xhci_dbg(xhci, "%s %s\n", __func__, decode_ep(ep, udev->speed));

        sch_ep = create_sch_ep(mtk, udev, ep, ep_ctx);
        if (IS_ERR_OR_NULL(sch_ep))
                return -ENOMEM;

        setup_sch_info(ep_ctx, sch_ep);

        list_add_tail(&sch_ep->endpoint, &mtk->bw_ep_chk_list);
        hash_add(mtk->sch_ep_hash, &sch_ep->hentry, (unsigned long)ep);

        return 0;
}

static void drop_ep_quirk(struct usb_hcd *hcd, struct usb_device *udev,
                          struct usb_host_endpoint *ep)
{
        struct xhci_hcd_mtk *mtk = hcd_to_mtk(hcd);
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct mu3h_sch_ep_info *sch_ep;
        struct hlist_node *hn;

        if (!need_bw_sch(udev, ep))
                return;

        xhci_dbg(xhci, "%s %s\n", __func__, decode_ep(ep, udev->speed));

        hash_for_each_possible_safe(mtk->sch_ep_hash, sch_ep,
                                    hn, hentry, (unsigned long)ep) {
                if (sch_ep->ep == ep) {
                        destroy_sch_ep(mtk, udev, sch_ep);
                        break;
                }
        }
}

int xhci_mtk_check_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
{
        struct xhci_hcd_mtk *mtk = hcd_to_mtk(hcd);
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct xhci_virt_device *virt_dev = xhci->devs[udev->slot_id];
        struct mu3h_sch_ep_info *sch_ep;
        int ret;

        xhci_dbg(xhci, "%s() udev %s\n", __func__, dev_name(&udev->dev));

        list_for_each_entry(sch_ep, &mtk->bw_ep_chk_list, endpoint) {
                struct xhci_ep_ctx *ep_ctx;
                struct usb_host_endpoint *ep = sch_ep->ep;
                unsigned int ep_index = xhci_get_endpoint_index(&ep->desc);

                ret = check_sch_bw(sch_ep);
                if (ret) {
                        xhci_err(xhci, "Not enough bandwidth! (%s)\n",
                                 sch_error_string(-ret));
                        return -ENOSPC;
                }

                ep_ctx = xhci_get_ep_ctx(xhci, virt_dev->in_ctx, ep_index);
                ep_ctx->reserved[0] = cpu_to_le32(EP_BPKTS(sch_ep->pkts)
                        | EP_BCSCOUNT(sch_ep->cs_count)
                        | EP_BBM(sch_ep->burst_mode));
                ep_ctx->reserved[1] = cpu_to_le32(EP_BOFFSET(sch_ep->offset)
                        | EP_BREPEAT(sch_ep->repeat));

                xhci_dbg(xhci, " PKTS:%x, CSCOUNT:%x, BM:%x, OFFSET:%x, REPEAT:%x\n",
                        sch_ep->pkts, sch_ep->cs_count, sch_ep->burst_mode,
                        sch_ep->offset, sch_ep->repeat);
        }

        ret = xhci_check_bandwidth(hcd, udev);
        if (!ret)
                list_del_init(&mtk->bw_ep_chk_list);

        return ret;
}

void xhci_mtk_reset_bandwidth(struct usb_hcd *hcd, struct usb_device *udev)
{
        struct xhci_hcd_mtk *mtk = hcd_to_mtk(hcd);
        struct xhci_hcd *xhci = hcd_to_xhci(hcd);
        struct mu3h_sch_ep_info *sch_ep, *tmp;

        xhci_dbg(xhci, "%s() udev %s\n", __func__, dev_name(&udev->dev));

        list_for_each_entry_safe(sch_ep, tmp, &mtk->bw_ep_chk_list, endpoint)
                destroy_sch_ep(mtk, udev, sch_ep);

        xhci_reset_bandwidth(hcd, udev);
}

int xhci_mtk_add_ep(struct usb_hcd *hcd, struct usb_device *udev,
                    struct usb_host_endpoint *ep)
{
        int ret;

        ret = xhci_add_endpoint(hcd, udev, ep);
        if (ret)
                return ret;

        if (ep->hcpriv)
                ret = add_ep_quirk(hcd, udev, ep);

        return ret;
}

int xhci_mtk_drop_ep(struct usb_hcd *hcd, struct usb_device *udev,
                     struct usb_host_endpoint *ep)
{
        int ret;

        ret = xhci_drop_endpoint(hcd, udev, ep);
        if (ret)
                return ret;

        /* needn't check @ep->hcpriv, xhci_endpoint_disable set it NULL */
        drop_ep_quirk(hcd, udev, ep);

        return 0;
}