root/drivers/usb/host/ohci-dbg.c
// SPDX-License-Identifier: GPL-1.0+
/*
 * OHCI HCD (Host Controller Driver) for USB.
 *
 * (C) Copyright 1999 Roman Weissgaerber <weissg@vienna.at>
 * (C) Copyright 2000-2002 David Brownell <dbrownell@users.sourceforge.net>
 *
 * This file is licenced under the GPL.
 */

/*-------------------------------------------------------------------------*/

#define edstring(ed_type) ({ char *temp; \
        switch (ed_type) { \
        case PIPE_CONTROL:      temp = "ctrl"; break; \
        case PIPE_BULK:         temp = "bulk"; break; \
        case PIPE_INTERRUPT:    temp = "intr"; break; \
        default:                temp = "isoc"; break; \
        } temp;})
#define pipestring(pipe) edstring(usb_pipetype(pipe))


#define ohci_dbg_sw(ohci, next, size, format, arg...) \
        do { \
        if (next != NULL) { \
                unsigned s_len; \
                s_len = scnprintf (*next, *size, format, ## arg ); \
                *size -= s_len; *next += s_len; \
        } else \
                ohci_dbg(ohci,format, ## arg ); \
        } while (0);

/* Version for use where "next" is the address of a local variable */
#define ohci_dbg_nosw(ohci, next, size, format, arg...) \
        do { \
                unsigned s_len; \
                s_len = scnprintf(*next, *size, format, ## arg); \
                *size -= s_len; *next += s_len; \
        } while (0);


static void ohci_dump_intr_mask (
        struct ohci_hcd *ohci,
        char *label,
        u32 mask,
        char **next,
        unsigned *size)
{
        ohci_dbg_sw (ohci, next, size, "%s 0x%08x%s%s%s%s%s%s%s%s%s\n",
                label,
                mask,
                (mask & OHCI_INTR_MIE) ? " MIE" : "",
                (mask & OHCI_INTR_OC) ? " OC" : "",
                (mask & OHCI_INTR_RHSC) ? " RHSC" : "",
                (mask & OHCI_INTR_FNO) ? " FNO" : "",
                (mask & OHCI_INTR_UE) ? " UE" : "",
                (mask & OHCI_INTR_RD) ? " RD" : "",
                (mask & OHCI_INTR_SF) ? " SF" : "",
                (mask & OHCI_INTR_WDH) ? " WDH" : "",
                (mask & OHCI_INTR_SO) ? " SO" : ""
                );
}

static void maybe_print_eds (
        struct ohci_hcd *ohci,
        char *label,
        u32 value,
        char **next,
        unsigned *size)
{
        if (value)
                ohci_dbg_sw (ohci, next, size, "%s %08x\n", label, value);
}

static char *hcfs2string (int state)
{
        switch (state) {
                case OHCI_USB_RESET:    return "reset";
                case OHCI_USB_RESUME:   return "resume";
                case OHCI_USB_OPER:     return "operational";
                case OHCI_USB_SUSPEND:  return "suspend";
        }
        return "?";
}

static const char *rh_state_string(struct ohci_hcd *ohci)
{
        switch (ohci->rh_state) {
        case OHCI_RH_HALTED:
                return "halted";
        case OHCI_RH_SUSPENDED:
                return "suspended";
        case OHCI_RH_RUNNING:
                return "running";
        }
        return "?";
}

// dump control and status registers
static void
ohci_dump_status (struct ohci_hcd *controller, char **next, unsigned *size)
{
        struct ohci_regs __iomem *regs = controller->regs;
        u32                     temp;

        temp = ohci_readl (controller, &regs->revision) & 0xff;
        ohci_dbg_sw (controller, next, size,
                "OHCI %d.%d, %s legacy support registers, rh state %s\n",
                0x03 & (temp >> 4), (temp & 0x0f),
                (temp & 0x0100) ? "with" : "NO",
                rh_state_string(controller));

        temp = ohci_readl (controller, &regs->control);
        ohci_dbg_sw (controller, next, size,
                "control 0x%03x%s%s%s HCFS=%s%s%s%s%s CBSR=%d\n",
                temp,
                (temp & OHCI_CTRL_RWE) ? " RWE" : "",
                (temp & OHCI_CTRL_RWC) ? " RWC" : "",
                (temp & OHCI_CTRL_IR) ? " IR" : "",
                hcfs2string (temp & OHCI_CTRL_HCFS),
                (temp & OHCI_CTRL_BLE) ? " BLE" : "",
                (temp & OHCI_CTRL_CLE) ? " CLE" : "",
                (temp & OHCI_CTRL_IE) ? " IE" : "",
                (temp & OHCI_CTRL_PLE) ? " PLE" : "",
                temp & OHCI_CTRL_CBSR
                );

        temp = ohci_readl (controller, &regs->cmdstatus);
        ohci_dbg_sw (controller, next, size,
                "cmdstatus 0x%05x SOC=%d%s%s%s%s\n", temp,
                (temp & OHCI_SOC) >> 16,
                (temp & OHCI_OCR) ? " OCR" : "",
                (temp & OHCI_BLF) ? " BLF" : "",
                (temp & OHCI_CLF) ? " CLF" : "",
                (temp & OHCI_HCR) ? " HCR" : ""
                );

        ohci_dump_intr_mask (controller, "intrstatus",
                        ohci_readl (controller, &regs->intrstatus),
                        next, size);
        ohci_dump_intr_mask (controller, "intrenable",
                        ohci_readl (controller, &regs->intrenable),
                        next, size);
        // intrdisable always same as intrenable

        maybe_print_eds (controller, "ed_periodcurrent",
                        ohci_readl (controller, &regs->ed_periodcurrent),
                        next, size);

        maybe_print_eds (controller, "ed_controlhead",
                        ohci_readl (controller, &regs->ed_controlhead),
                        next, size);
        maybe_print_eds (controller, "ed_controlcurrent",
                        ohci_readl (controller, &regs->ed_controlcurrent),
                        next, size);

        maybe_print_eds (controller, "ed_bulkhead",
                        ohci_readl (controller, &regs->ed_bulkhead),
                        next, size);
        maybe_print_eds (controller, "ed_bulkcurrent",
                        ohci_readl (controller, &regs->ed_bulkcurrent),
                        next, size);

        maybe_print_eds (controller, "donehead",
                        ohci_readl (controller, &regs->donehead), next, size);
}

#define dbg_port_sw(hc,num,value,next,size) \
        ohci_dbg_sw (hc, next, size, \
                "roothub.portstatus [%d] " \
                "0x%08x%s%s%s%s%s%s%s%s%s%s%s%s\n", \
                num, temp, \
                (temp & RH_PS_PRSC) ? " PRSC" : "", \
                (temp & RH_PS_OCIC) ? " OCIC" : "", \
                (temp & RH_PS_PSSC) ? " PSSC" : "", \
                (temp & RH_PS_PESC) ? " PESC" : "", \
                (temp & RH_PS_CSC) ? " CSC" : "", \
                \
                (temp & RH_PS_LSDA) ? " LSDA" : "", \
                (temp & RH_PS_PPS) ? " PPS" : "", \
                (temp & RH_PS_PRS) ? " PRS" : "", \
                (temp & RH_PS_POCI) ? " POCI" : "", \
                (temp & RH_PS_PSS) ? " PSS" : "", \
                \
                (temp & RH_PS_PES) ? " PES" : "", \
                (temp & RH_PS_CCS) ? " CCS" : "" \
                );


static void
ohci_dump_roothub (
        struct ohci_hcd *controller,
        int verbose,
        char **next,
        unsigned *size)
{
        u32                     temp, i;

        temp = roothub_a (controller);
        if (temp == ~(u32)0)
                return;

        if (verbose) {
                ohci_dbg_sw (controller, next, size,
                        "roothub.a %08x POTPGT=%d%s%s%s%s%s NDP=%d(%d)\n", temp,
                        ((temp & RH_A_POTPGT) >> 24) & 0xff,
                        (temp & RH_A_NOCP) ? " NOCP" : "",
                        (temp & RH_A_OCPM) ? " OCPM" : "",
                        (temp & RH_A_DT) ? " DT" : "",
                        (temp & RH_A_NPS) ? " NPS" : "",
                        (temp & RH_A_PSM) ? " PSM" : "",
                        (temp & RH_A_NDP), controller->num_ports
                        );
                temp = roothub_b (controller);
                ohci_dbg_sw (controller, next, size,
                        "roothub.b %08x PPCM=%04x DR=%04x\n",
                        temp,
                        (temp & RH_B_PPCM) >> 16,
                        (temp & RH_B_DR)
                        );
                temp = roothub_status (controller);
                ohci_dbg_sw (controller, next, size,
                        "roothub.status %08x%s%s%s%s%s%s\n",
                        temp,
                        (temp & RH_HS_CRWE) ? " CRWE" : "",
                        (temp & RH_HS_OCIC) ? " OCIC" : "",
                        (temp & RH_HS_LPSC) ? " LPSC" : "",
                        (temp & RH_HS_DRWE) ? " DRWE" : "",
                        (temp & RH_HS_OCI) ? " OCI" : "",
                        (temp & RH_HS_LPS) ? " LPS" : ""
                        );
        }

        for (i = 0; i < controller->num_ports; i++) {
                temp = roothub_portstatus (controller, i);
                dbg_port_sw (controller, i, temp, next, size);
        }
}

static void ohci_dump(struct ohci_hcd *controller)
{
        ohci_dbg (controller, "OHCI controller state\n");

        // dumps some of the state we know about
        ohci_dump_status (controller, NULL, NULL);
        if (controller->hcca)
                ohci_dbg (controller,
                        "hcca frame #%04x\n", ohci_frame_no(controller));
        ohci_dump_roothub (controller, 1, NULL, NULL);
}

static const char data0 [] = "DATA0";
static const char data1 [] = "DATA1";

static void ohci_dump_td (const struct ohci_hcd *ohci, const char *label,
                const struct td *td)
{
        u32     tmp = hc32_to_cpup (ohci, &td->hwINFO);

        ohci_dbg (ohci, "%s td %p%s; urb %p index %d; hw next td %08x\n",
                label, td,
                (tmp & TD_DONE) ? " (DONE)" : "",
                td->urb, td->index,
                hc32_to_cpup (ohci, &td->hwNextTD));
        if ((tmp & TD_ISO) == 0) {
                const char      *toggle, *pid;
                u32     cbp, be;

                switch (tmp & TD_T) {
                case TD_T_DATA0: toggle = data0; break;
                case TD_T_DATA1: toggle = data1; break;
                case TD_T_TOGGLE: toggle = "(CARRY)"; break;
                default: toggle = "(?)"; break;
                }
                switch (tmp & TD_DP) {
                case TD_DP_SETUP: pid = "SETUP"; break;
                case TD_DP_IN: pid = "IN"; break;
                case TD_DP_OUT: pid = "OUT"; break;
                default: pid = "(bad pid)"; break;
                }
                ohci_dbg (ohci, "     info %08x CC=%x %s DI=%d %s %s\n", tmp,
                        TD_CC_GET(tmp), /* EC, */ toggle,
                        (tmp & TD_DI) >> 21, pid,
                        (tmp & TD_R) ? "R" : "");
                cbp = hc32_to_cpup (ohci, &td->hwCBP);
                be = hc32_to_cpup (ohci, &td->hwBE);
                ohci_dbg (ohci, "     cbp %08x be %08x (len %d)\n", cbp, be,
                        cbp ? (be + 1 - cbp) : 0);
        } else {
                unsigned        i;
                ohci_dbg (ohci, "  info %08x CC=%x FC=%d DI=%d SF=%04x\n", tmp,
                        TD_CC_GET(tmp),
                        (tmp >> 24) & 0x07,
                        (tmp & TD_DI) >> 21,
                        tmp & 0x0000ffff);
                ohci_dbg (ohci, "  bp0 %08x be %08x\n",
                        hc32_to_cpup (ohci, &td->hwCBP) & ~0x0fff,
                        hc32_to_cpup (ohci, &td->hwBE));
                for (i = 0; i < MAXPSW; i++) {
                        u16     psw = ohci_hwPSW (ohci, td, i);
                        int     cc = (psw >> 12) & 0x0f;
                        ohci_dbg (ohci, "    psw [%d] = %2x, CC=%x %s=%d\n", i,
                                psw, cc,
                                (cc >= 0x0e) ? "OFFSET" : "SIZE",
                                psw & 0x0fff);
                }
        }
}

/* caller MUST own hcd spinlock if verbose is set! */
static void __maybe_unused
ohci_dump_ed (const struct ohci_hcd *ohci, const char *label,
                const struct ed *ed, int verbose)
{
        u32     tmp = hc32_to_cpu (ohci, ed->hwINFO);
        char    *type = "";

        ohci_dbg (ohci, "%s, ed %p state 0x%x type %s; next ed %08x\n",
                label,
                ed, ed->state, edstring (ed->type),
                hc32_to_cpup (ohci, &ed->hwNextED));
        switch (tmp & (ED_IN|ED_OUT)) {
        case ED_OUT: type = "-OUT"; break;
        case ED_IN: type = "-IN"; break;
        /* else from TDs ... control */
        }
        ohci_dbg (ohci,
                "  info %08x MAX=%d%s%s%s%s EP=%d%s DEV=%d\n", tmp,
                0x03ff & (tmp >> 16),
                (tmp & ED_DEQUEUE) ? " DQ" : "",
                (tmp & ED_ISO) ? " ISO" : "",
                (tmp & ED_SKIP) ? " SKIP" : "",
                (tmp & ED_LOWSPEED) ? " LOW" : "",
                0x000f & (tmp >> 7),
                type,
                0x007f & tmp);
        tmp = hc32_to_cpup (ohci, &ed->hwHeadP);
        ohci_dbg (ohci, "  tds: head %08x %s%s tail %08x%s\n",
                tmp,
                (tmp & ED_C) ? data1 : data0,
                (tmp & ED_H) ? " HALT" : "",
                hc32_to_cpup (ohci, &ed->hwTailP),
                verbose ? "" : " (not listing)");
        if (verbose) {
                struct list_head        *tmp;

                /* use ed->td_list because HC concurrently modifies
                 * hwNextTD as it accumulates ed_donelist.
                 */
                list_for_each (tmp, &ed->td_list) {
                        struct td               *td;
                        td = list_entry (tmp, struct td, td_list);
                        ohci_dump_td (ohci, "  ->", td);
                }
        }
}

/*-------------------------------------------------------------------------*/

static int debug_async_open(struct inode *, struct file *);
static int debug_periodic_open(struct inode *, struct file *);
static int debug_registers_open(struct inode *, struct file *);
static int debug_async_open(struct inode *, struct file *);
static ssize_t debug_output(struct file*, char __user*, size_t, loff_t*);
static int debug_close(struct inode *, struct file *);

static const struct file_operations debug_async_fops = {
        .owner          = THIS_MODULE,
        .open           = debug_async_open,
        .read           = debug_output,
        .release        = debug_close,
        .llseek         = default_llseek,
};
static const struct file_operations debug_periodic_fops = {
        .owner          = THIS_MODULE,
        .open           = debug_periodic_open,
        .read           = debug_output,
        .release        = debug_close,
        .llseek         = default_llseek,
};
static const struct file_operations debug_registers_fops = {
        .owner          = THIS_MODULE,
        .open           = debug_registers_open,
        .read           = debug_output,
        .release        = debug_close,
        .llseek         = default_llseek,
};

static struct dentry *ohci_debug_root;

struct debug_buffer {
        ssize_t (*fill_func)(struct debug_buffer *);    /* fill method */
        struct ohci_hcd *ohci;
        struct mutex mutex;     /* protect filling of buffer */
        size_t count;           /* number of characters filled into buffer */
        char *page;
};

static ssize_t
show_list (struct ohci_hcd *ohci, char *buf, size_t count, struct ed *ed)
{
        unsigned                temp, size = count;

        if (!ed)
                return 0;

        /* print first --> last */
        while (ed->ed_prev)
                ed = ed->ed_prev;

        /* dump a snapshot of the bulk or control schedule */
        while (ed) {
                u32             info = hc32_to_cpu (ohci, ed->hwINFO);
                u32             headp = hc32_to_cpu (ohci, ed->hwHeadP);
                struct list_head *entry;
                struct td       *td;

                temp = scnprintf (buf, size,
                        "ed/%p %cs dev%d ep%d%s max %d %08x%s%s %s",
                        ed,
                        (info & ED_LOWSPEED) ? 'l' : 'f',
                        info & 0x7f,
                        (info >> 7) & 0xf,
                        (info & ED_IN) ? "in" : "out",
                        0x03ff & (info >> 16),
                        info,
                        (info & ED_SKIP) ? " s" : "",
                        (headp & ED_H) ? " H" : "",
                        (headp & ED_C) ? data1 : data0);
                size -= temp;
                buf += temp;

                list_for_each (entry, &ed->td_list) {
                        u32             cbp, be;

                        td = list_entry (entry, struct td, td_list);
                        info = hc32_to_cpup (ohci, &td->hwINFO);
                        cbp = hc32_to_cpup (ohci, &td->hwCBP);
                        be = hc32_to_cpup (ohci, &td->hwBE);
                        temp = scnprintf (buf, size,
                                        "\n\ttd %p %s %d cc=%x urb %p (%08x)",
                                        td,
                                        ({ char *pid;
                                        switch (info & TD_DP) {
                                        case TD_DP_SETUP: pid = "setup"; break;
                                        case TD_DP_IN: pid = "in"; break;
                                        case TD_DP_OUT: pid = "out"; break;
                                        default: pid = "(?)"; break;
                                         } pid;}),
                                        cbp ? (be + 1 - cbp) : 0,
                                        TD_CC_GET (info), td->urb, info);
                        size -= temp;
                        buf += temp;
                }

                temp = scnprintf (buf, size, "\n");
                size -= temp;
                buf += temp;

                ed = ed->ed_next;
        }
        return count - size;
}

static ssize_t fill_async_buffer(struct debug_buffer *buf)
{
        struct ohci_hcd         *ohci;
        size_t                  temp, size;
        unsigned long           flags;

        ohci = buf->ohci;
        size = PAGE_SIZE;

        /* display control and bulk lists together, for simplicity */
        spin_lock_irqsave (&ohci->lock, flags);
        temp = show_list(ohci, buf->page, size, ohci->ed_controltail);
        temp += show_list(ohci, buf->page + temp, size - temp,
                          ohci->ed_bulktail);
        spin_unlock_irqrestore (&ohci->lock, flags);

        return temp;
}

#define DBG_SCHED_LIMIT 64

static ssize_t fill_periodic_buffer(struct debug_buffer *buf)
{
        struct ohci_hcd         *ohci;
        struct ed               **seen, *ed;
        unsigned long           flags;
        unsigned                temp, size, seen_count;
        char                    *next;
        unsigned                i;

        seen = kmalloc_objs(*seen, DBG_SCHED_LIMIT, GFP_ATOMIC);
        if (!seen)
                return 0;
        seen_count = 0;

        ohci = buf->ohci;
        next = buf->page;
        size = PAGE_SIZE;

        temp = scnprintf (next, size, "size = %d\n", NUM_INTS);
        size -= temp;
        next += temp;

        /* dump a snapshot of the periodic schedule (and load) */
        spin_lock_irqsave (&ohci->lock, flags);
        for (i = 0; i < NUM_INTS; i++) {
                ed = ohci->periodic[i];
                if (!ed)
                        continue;

                temp = scnprintf (next, size, "%2d [%3d]:", i, ohci->load [i]);
                size -= temp;
                next += temp;

                do {
                        temp = scnprintf (next, size, " ed%d/%p",
                                ed->interval, ed);
                        size -= temp;
                        next += temp;
                        for (temp = 0; temp < seen_count; temp++) {
                                if (seen [temp] == ed)
                                        break;
                        }

                        /* show more info the first time around */
                        if (temp == seen_count) {
                                u32     info = hc32_to_cpu (ohci, ed->hwINFO);
                                struct list_head        *entry;
                                unsigned                qlen = 0;

                                /* qlen measured here in TDs, not urbs */
                                list_for_each (entry, &ed->td_list)
                                        qlen++;

                                temp = scnprintf (next, size,
                                        " (%cs dev%d ep%d%s-%s qlen %u"
                                        " max %d %08x%s%s)",
                                        (info & ED_LOWSPEED) ? 'l' : 'f',
                                        info & 0x7f,
                                        (info >> 7) & 0xf,
                                        (info & ED_IN) ? "in" : "out",
                                        (info & ED_ISO) ? "iso" : "int",
                                        qlen,
                                        0x03ff & (info >> 16),
                                        info,
                                        (info & ED_SKIP) ? " K" : "",
                                        (ed->hwHeadP &
                                                cpu_to_hc32(ohci, ED_H)) ?
                                                        " H" : "");
                                size -= temp;
                                next += temp;

                                if (seen_count < DBG_SCHED_LIMIT)
                                        seen [seen_count++] = ed;

                                ed = ed->ed_next;

                        } else {
                                /* we've seen it and what's after */
                                temp = 0;
                                ed = NULL;
                        }

                } while (ed);

                temp = scnprintf (next, size, "\n");
                size -= temp;
                next += temp;
        }
        spin_unlock_irqrestore (&ohci->lock, flags);
        kfree (seen);

        return PAGE_SIZE - size;
}
#undef DBG_SCHED_LIMIT

static ssize_t fill_registers_buffer(struct debug_buffer *buf)
{
        struct usb_hcd          *hcd;
        struct ohci_hcd         *ohci;
        struct ohci_regs __iomem *regs;
        unsigned long           flags;
        unsigned                temp, size;
        char                    *next;
        u32                     rdata;

        ohci = buf->ohci;
        hcd = ohci_to_hcd(ohci);
        regs = ohci->regs;
        next = buf->page;
        size = PAGE_SIZE;

        spin_lock_irqsave (&ohci->lock, flags);

        /* dump driver info, then registers in spec order */

        ohci_dbg_nosw(ohci, &next, &size,
                "bus %s, device %s\n"
                "%s\n"
                "%s\n",
                hcd->self.controller->bus->name,
                dev_name(hcd->self.controller),
                hcd->product_desc,
                hcd_name);

        if (!HCD_HW_ACCESSIBLE(hcd)) {
                size -= scnprintf (next, size,
                        "SUSPENDED (no register access)\n");
                goto done;
        }

        ohci_dump_status(ohci, &next, &size);

        /* hcca */
        if (ohci->hcca)
                ohci_dbg_nosw(ohci, &next, &size,
                        "hcca frame 0x%04x\n", ohci_frame_no(ohci));

        /* other registers mostly affect frame timings */
        rdata = ohci_readl (ohci, &regs->fminterval);
        temp = scnprintf (next, size,
                        "fmintvl 0x%08x %sFSMPS=0x%04x FI=0x%04x\n",
                        rdata, (rdata >> 31) ? "FIT " : "",
                        (rdata >> 16) & 0xefff, rdata & 0xffff);
        size -= temp;
        next += temp;

        rdata = ohci_readl (ohci, &regs->fmremaining);
        temp = scnprintf (next, size, "fmremaining 0x%08x %sFR=0x%04x\n",
                        rdata, (rdata >> 31) ? "FRT " : "",
                        rdata & 0x3fff);
        size -= temp;
        next += temp;

        rdata = ohci_readl (ohci, &regs->periodicstart);
        temp = scnprintf (next, size, "periodicstart 0x%04x\n",
                        rdata & 0x3fff);
        size -= temp;
        next += temp;

        rdata = ohci_readl (ohci, &regs->lsthresh);
        temp = scnprintf (next, size, "lsthresh 0x%04x\n",
                        rdata & 0x3fff);
        size -= temp;
        next += temp;

        temp = scnprintf (next, size, "hub poll timer %s\n",
                        HCD_POLL_RH(ohci_to_hcd(ohci)) ? "ON" : "off");
        size -= temp;
        next += temp;

        /* roothub */
        ohci_dump_roothub (ohci, 1, &next, &size);

done:
        spin_unlock_irqrestore (&ohci->lock, flags);

        return PAGE_SIZE - size;
}

static struct debug_buffer *alloc_buffer(struct ohci_hcd *ohci,
                                ssize_t (*fill_func)(struct debug_buffer *))
{
        struct debug_buffer *buf;

        buf = kzalloc_obj(struct debug_buffer);

        if (buf) {
                buf->ohci = ohci;
                buf->fill_func = fill_func;
                mutex_init(&buf->mutex);
        }

        return buf;
}

static int fill_buffer(struct debug_buffer *buf)
{
        int ret;

        if (!buf->page)
                buf->page = (char *)get_zeroed_page(GFP_KERNEL);

        if (!buf->page) {
                ret = -ENOMEM;
                goto out;
        }

        ret = buf->fill_func(buf);

        if (ret >= 0) {
                buf->count = ret;
                ret = 0;
        }

out:
        return ret;
}

static ssize_t debug_output(struct file *file, char __user *user_buf,
                        size_t len, loff_t *offset)
{
        struct debug_buffer *buf = file->private_data;
        int ret;

        mutex_lock(&buf->mutex);
        if (buf->count == 0) {
                ret = fill_buffer(buf);
                if (ret != 0) {
                        mutex_unlock(&buf->mutex);
                        goto out;
                }
        }
        mutex_unlock(&buf->mutex);

        ret = simple_read_from_buffer(user_buf, len, offset,
                                      buf->page, buf->count);

out:
        return ret;

}

static int debug_close(struct inode *inode, struct file *file)
{
        struct debug_buffer *buf = file->private_data;

        if (buf) {
                if (buf->page)
                        free_page((unsigned long)buf->page);
                kfree(buf);
        }

        return 0;
}
static int debug_async_open(struct inode *inode, struct file *file)
{
        file->private_data = alloc_buffer(inode->i_private, fill_async_buffer);

        return file->private_data ? 0 : -ENOMEM;
}

static int debug_periodic_open(struct inode *inode, struct file *file)
{
        file->private_data = alloc_buffer(inode->i_private,
                                          fill_periodic_buffer);

        return file->private_data ? 0 : -ENOMEM;
}

static int debug_registers_open(struct inode *inode, struct file *file)
{
        file->private_data = alloc_buffer(inode->i_private,
                                          fill_registers_buffer);

        return file->private_data ? 0 : -ENOMEM;
}
static inline void create_debug_files (struct ohci_hcd *ohci)
{
        struct usb_bus *bus = &ohci_to_hcd(ohci)->self;
        struct dentry *root;

        root = debugfs_create_dir(bus->bus_name, ohci_debug_root);
        ohci->debug_dir = root;

        debugfs_create_file("async", S_IRUGO, root, ohci, &debug_async_fops);
        debugfs_create_file("periodic", S_IRUGO, root, ohci,
                            &debug_periodic_fops);
        debugfs_create_file("registers", S_IRUGO, root, ohci,
                            &debug_registers_fops);

        ohci_dbg (ohci, "created debug files\n");
}

static inline void remove_debug_files (struct ohci_hcd *ohci)
{
        debugfs_remove_recursive(ohci->debug_dir);
}

/*-------------------------------------------------------------------------*/