mv_otg.c

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/*
 * Copyright (C) 2011 Marvell International Ltd. All rights reserved.
 * Author: Chao Xie <[email protected]>
 *     Neil Zhang <[email protected]>
 *
 * 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.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/device.h>
#include <linux/proc_fs.h>
#include <linux/clk.h>
#include <linux/workqueue.h>
#include <linux/platform_device.h>

#include <linux/usb.h>
#include <linux/usb/ch9.h>
#include <linux/usb/otg.h>
#include <linux/usb/gadget.h>
#include <linux/usb/hcd.h>
#include <linux/platform_data/mv_usb.h>

#include "mv_otg.h"

#define DRIVER_DESC "Marvell USB OTG transceiver driver"
#define DRIVER_VERSION  "Jan 20, 2010"

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL");

static const char driver_name[] = "mv-otg";

static char *state_string[] = {
    "undefined",
    "b_idle",
    "b_srp_init",
    "b_peripheral",
    "b_wait_acon",
    "b_host",
    "a_idle",
    "a_wait_vrise",
    "a_wait_bcon",
    "a_host",
    "a_suspend",
    "a_peripheral",
    "a_wait_vfall",
    "a_vbus_err"
};

static int mv_otg_set_vbus(struct usb_otg *otg, bool on)
{
    struct mv_otg *mvotg = container_of(otg->phy, struct mv_otg, phy);
    if (mvotg->pdata->set_vbus == NULL)
        return -ENODEV;

    return mvotg->pdata->set_vbus(on);
}

static int mv_otg_set_host(struct usb_otg *otg,
               struct usb_bus *host)
{
    otg->host = host;

    return 0;
}

static int mv_otg_set_peripheral(struct usb_otg *otg,
                 struct usb_gadget *gadget)
{
    otg->gadget = gadget;

    return 0;
}

static void mv_otg_run_state_machine(struct mv_otg *mvotg,
                     unsigned long delay)
{
    dev_dbg(&mvotg->pdev->dev, "transceiver is updated\n");
    if (!mvotg->qwork)
        return;

    queue_delayed_work(mvotg->qwork, &mvotg->work, delay);
}

static void mv_otg_timer_await_bcon(unsigned long data)
{
    struct mv_otg *mvotg = (struct mv_otg *) data;

    mvotg->otg_ctrl.a_wait_bcon_timeout = 1;

    dev_info(&mvotg->pdev->dev, "B Device No Response!\n");

    if (spin_trylock(&mvotg->wq_lock)) {
        mv_otg_run_state_machine(mvotg, 0);
        spin_unlock(&mvotg->wq_lock);
    }
}

static int mv_otg_cancel_timer(struct mv_otg *mvotg, unsigned int id)
{
    struct timer_list *timer;

    if (id >= OTG_TIMER_NUM)
        return -EINVAL;

    timer = &mvotg->otg_ctrl.timer[id];

    if (timer_pending(timer))
        del_timer(timer);

    return 0;
}

static int mv_otg_set_timer(struct mv_otg *mvotg, unsigned int id,
                unsigned long interval,
                void (*callback) (unsigned long))
{
    struct timer_list *timer;

    if (id >= OTG_TIMER_NUM)
        return -EINVAL;

    timer = &mvotg->otg_ctrl.timer[id];
    if (timer_pending(timer)) {
        dev_err(&mvotg->pdev->dev, "Timer%d is already running\n", id);
        return -EBUSY;
    }

    init_timer(timer);
    timer->data = (unsigned long) mvotg;
    timer->function = callback;
    timer->expires = jiffies + interval;
    add_timer(timer);

    return 0;
}

static int mv_otg_reset(struct mv_otg *mvotg)
{
    unsigned int loops;
    u32 tmp;

    /* Stop the controller */
    tmp = readl(&mvotg->op_regs->usbcmd);
    tmp &= ~USBCMD_RUN_STOP;
    writel(tmp, &mvotg->op_regs->usbcmd);

    /* Reset the controller to get default values */
    writel(USBCMD_CTRL_RESET, &mvotg->op_regs->usbcmd);

    loops = 500;
    while (readl(&mvotg->op_regs->usbcmd) & USBCMD_CTRL_RESET) {
        if (loops == 0) {
            dev_err(&mvotg->pdev->dev,
                "Wait for RESET completed TIMEOUT\n");
            return -ETIMEDOUT;
        }
        loops--;
        udelay(20);
    }

    writel(0x0, &mvotg->op_regs->usbintr);
    tmp = readl(&mvotg->op_regs->usbsts);
    writel(tmp, &mvotg->op_regs->usbsts);

    return 0;
}

static void mv_otg_init_irq(struct mv_otg *mvotg)
{
    u32 otgsc;

    mvotg->irq_en = OTGSC_INTR_A_SESSION_VALID
        | OTGSC_INTR_A_VBUS_VALID;
    mvotg->irq_status = OTGSC_INTSTS_A_SESSION_VALID
        | OTGSC_INTSTS_A_VBUS_VALID;

    if (mvotg->pdata->vbus == NULL) {
        mvotg->irq_en |= OTGSC_INTR_B_SESSION_VALID
            | OTGSC_INTR_B_SESSION_END;
        mvotg->irq_status |= OTGSC_INTSTS_B_SESSION_VALID
            | OTGSC_INTSTS_B_SESSION_END;
    }

    if (mvotg->pdata->id == NULL) {
        mvotg->irq_en |= OTGSC_INTR_USB_ID;
        mvotg->irq_status |= OTGSC_INTSTS_USB_ID;
    }

    otgsc = readl(&mvotg->op_regs->otgsc);
    otgsc |= mvotg->irq_en;
    writel(otgsc, &mvotg->op_regs->otgsc);
}

static void mv_otg_start_host(struct mv_otg *mvotg, int on)
{
#ifdef CONFIG_USB
    struct usb_otg *otg = mvotg->phy.otg;
    struct usb_hcd *hcd;

    if (!otg->host)
        return;

    dev_info(&mvotg->pdev->dev, "%s host\n", on ? "start" : "stop");

    hcd = bus_to_hcd(otg->host);

    if (on)
        usb_add_hcd(hcd, hcd->irq, IRQF_SHARED);
    else
        usb_remove_hcd(hcd);
#endif /* CONFIG_USB */
}

static void mv_otg_start_periphrals(struct mv_otg *mvotg, int on)
{
    struct usb_otg *otg = mvotg->phy.otg;

    if (!otg->gadget)
        return;

    dev_info(mvotg->phy.dev, "gadget %s\n", on ? "on" : "off");

    if (on)
        usb_gadget_vbus_connect(otg->gadget);
    else
        usb_gadget_vbus_disconnect(otg->gadget);
}

static void otg_clock_enable(struct mv_otg *mvotg)
{
    unsigned int i;

    for (i = 0; i < mvotg->clknum; i++)
        clk_enable(mvotg->clk[i]);
}

static void otg_clock_disable(struct mv_otg *mvotg)
{
    unsigned int i;

    for (i = 0; i < mvotg->clknum; i++)
        clk_disable(mvotg->clk[i]);
}

static int mv_otg_enable_internal(struct mv_otg *mvotg)
{
    int retval = 0;

    if (mvotg->active)
        return 0;

    dev_dbg(&mvotg->pdev->dev, "otg enabled\n");

    otg_clock_enable(mvotg);
    if (mvotg->pdata->phy_init) {
        retval = mvotg->pdata->phy_init(mvotg->phy_regs);
        if (retval) {
            dev_err(&mvotg->pdev->dev,
                "init phy error %d\n", retval);
            otg_clock_disable(mvotg);
            return retval;
        }
    }
    mvotg->active = 1;

    return 0;

}

static int mv_otg_enable(struct mv_otg *mvotg)
{
    if (mvotg->clock_gating)
        return mv_otg_enable_internal(mvotg);

    return 0;
}

static void mv_otg_disable_internal(struct mv_otg *mvotg)
{
    if (mvotg->active) {
        dev_dbg(&mvotg->pdev->dev, "otg disabled\n");
        if (mvotg->pdata->phy_deinit)
            mvotg->pdata->phy_deinit(mvotg->phy_regs);
        otg_clock_disable(mvotg);
        mvotg->active = 0;
    }
}

static void mv_otg_disable(struct mv_otg *mvotg)
{
    if (mvotg->clock_gating)
        mv_otg_disable_internal(mvotg);
}

static void mv_otg_update_inputs(struct mv_otg *mvotg)
{
    struct mv_otg_ctrl *otg_ctrl = &mvotg->otg_ctrl;
    u32 otgsc;

    otgsc = readl(&mvotg->op_regs->otgsc);

    if (mvotg->pdata->vbus) {
        if (mvotg->pdata->vbus->poll() == VBUS_HIGH) {
            otg_ctrl->b_sess_vld = 1;
            otg_ctrl->b_sess_end = 0;
        } else {
            otg_ctrl->b_sess_vld = 0;
            otg_ctrl->b_sess_end = 1;
        }
    } else {
        otg_ctrl->b_sess_vld = !!(otgsc & OTGSC_STS_B_SESSION_VALID);
        otg_ctrl->b_sess_end = !!(otgsc & OTGSC_STS_B_SESSION_END);
    }

    if (mvotg->pdata->id)
        otg_ctrl->id = !!mvotg->pdata->id->poll();
    else
        otg_ctrl->id = !!(otgsc & OTGSC_STS_USB_ID);

    if (mvotg->pdata->otg_force_a_bus_req && !otg_ctrl->id)
        otg_ctrl->a_bus_req = 1;

    otg_ctrl->a_sess_vld = !!(otgsc & OTGSC_STS_A_SESSION_VALID);
    otg_ctrl->a_vbus_vld = !!(otgsc & OTGSC_STS_A_VBUS_VALID);

    dev_dbg(&mvotg->pdev->dev, "%s: ", __func__);
    dev_dbg(&mvotg->pdev->dev, "id %d\n", otg_ctrl->id);
    dev_dbg(&mvotg->pdev->dev, "b_sess_vld %d\n", otg_ctrl->b_sess_vld);
    dev_dbg(&mvotg->pdev->dev, "b_sess_end %d\n", otg_ctrl->b_sess_end);
    dev_dbg(&mvotg->pdev->dev, "a_vbus_vld %d\n", otg_ctrl->a_vbus_vld);
    dev_dbg(&mvotg->pdev->dev, "a_sess_vld %d\n", otg_ctrl->a_sess_vld);
}

static void mv_otg_update_state(struct mv_otg *mvotg)
{
    struct mv_otg_ctrl *otg_ctrl = &mvotg->otg_ctrl;
    struct usb_phy *phy = &mvotg->phy;
    int old_state = phy->state;

    switch (old_state) {
    case OTG_STATE_UNDEFINED:
        phy->state = OTG_STATE_B_IDLE;
        /* FALL THROUGH */
    case OTG_STATE_B_IDLE:
        if (otg_ctrl->id == 0)
            phy->state = OTG_STATE_A_IDLE;
        else if (otg_ctrl->b_sess_vld)
            phy->state = OTG_STATE_B_PERIPHERAL;
        break;
    case OTG_STATE_B_PERIPHERAL:
        if (!otg_ctrl->b_sess_vld || otg_ctrl->id == 0)
            phy->state = OTG_STATE_B_IDLE;
        break;
    case OTG_STATE_A_IDLE:
        if (otg_ctrl->id)
            phy->state = OTG_STATE_B_IDLE;
        else if (!(otg_ctrl->a_bus_drop) &&
             (otg_ctrl->a_bus_req || otg_ctrl->a_srp_det))
            phy->state = OTG_STATE_A_WAIT_VRISE;
        break;
    case OTG_STATE_A_WAIT_VRISE:
        if (otg_ctrl->a_vbus_vld)
            phy->state = OTG_STATE_A_WAIT_BCON;
        break;
    case OTG_STATE_A_WAIT_BCON:
        if (otg_ctrl->id || otg_ctrl->a_bus_drop
            || otg_ctrl->a_wait_bcon_timeout) {
            mv_otg_cancel_timer(mvotg, A_WAIT_BCON_TIMER);
            mvotg->otg_ctrl.a_wait_bcon_timeout = 0;
            phy->state = OTG_STATE_A_WAIT_VFALL;
            otg_ctrl->a_bus_req = 0;
        } else if (!otg_ctrl->a_vbus_vld) {
            mv_otg_cancel_timer(mvotg, A_WAIT_BCON_TIMER);
            mvotg->otg_ctrl.a_wait_bcon_timeout = 0;
            phy->state = OTG_STATE_A_VBUS_ERR;
        } else if (otg_ctrl->b_conn) {
            mv_otg_cancel_timer(mvotg, A_WAIT_BCON_TIMER);
            mvotg->otg_ctrl.a_wait_bcon_timeout = 0;
            phy->state = OTG_STATE_A_HOST;
        }
        break;
    case OTG_STATE_A_HOST:
        if (otg_ctrl->id || !otg_ctrl->b_conn
            || otg_ctrl->a_bus_drop)
            phy->state = OTG_STATE_A_WAIT_BCON;
        else if (!otg_ctrl->a_vbus_vld)
            phy->state = OTG_STATE_A_VBUS_ERR;
        break;
    case OTG_STATE_A_WAIT_VFALL:
        if (otg_ctrl->id
            || (!otg_ctrl->b_conn && otg_ctrl->a_sess_vld)
            || otg_ctrl->a_bus_req)
            phy->state = OTG_STATE_A_IDLE;
        break;
    case OTG_STATE_A_VBUS_ERR:
        if (otg_ctrl->id || otg_ctrl->a_clr_err
            || otg_ctrl->a_bus_drop) {
            otg_ctrl->a_clr_err = 0;
            phy->state = OTG_STATE_A_WAIT_VFALL;
        }
        break;
    default:
        break;
    }
}

static void mv_otg_work(struct work_struct *work)
{
    struct mv_otg *mvotg;
    struct usb_phy *phy;
    struct usb_otg *otg;
    int old_state;

    mvotg = container_of((struct delayed_work *)work, struct mv_otg, work);

run:
    /* work queue is single thread, or we need spin_lock to protect */
    phy = &mvotg->phy;
    otg = phy->otg;
    old_state = phy->state;

    if (!mvotg->active)
        return;

    mv_otg_update_inputs(mvotg);
    mv_otg_update_state(mvotg);

    if (old_state != phy->state) {
        dev_info(&mvotg->pdev->dev, "change from state %s to %s\n",
             state_string[old_state],
             state_string[phy->state]);

        switch (phy->state) {
        case OTG_STATE_B_IDLE:
            otg->default_a = 0;
            if (old_state == OTG_STATE_B_PERIPHERAL)
                mv_otg_start_periphrals(mvotg, 0);
            mv_otg_reset(mvotg);
            mv_otg_disable(mvotg);
            break;
        case OTG_STATE_B_PERIPHERAL:
            mv_otg_enable(mvotg);
            mv_otg_start_periphrals(mvotg, 1);
            break;
        case OTG_STATE_A_IDLE:
            otg->default_a = 1;
            mv_otg_enable(mvotg);
            if (old_state == OTG_STATE_A_WAIT_VFALL)
                mv_otg_start_host(mvotg, 0);
            mv_otg_reset(mvotg);
            break;
        case OTG_STATE_A_WAIT_VRISE:
            mv_otg_set_vbus(otg, 1);
            break;
        case OTG_STATE_A_WAIT_BCON:
            if (old_state != OTG_STATE_A_HOST)
                mv_otg_start_host(mvotg, 1);
            mv_otg_set_timer(mvotg, A_WAIT_BCON_TIMER,
                     T_A_WAIT_BCON,
                     mv_otg_timer_await_bcon);
            /*
             * Now, we directly enter A_HOST. So set b_conn = 1
             * here. In fact, it need host driver to notify us.
             */
            mvotg->otg_ctrl.b_conn = 1;
            break;
        case OTG_STATE_A_HOST:
            break;
        case OTG_STATE_A_WAIT_VFALL:
            /*
             * Now, we has exited A_HOST. So set b_conn = 0
             * here. In fact, it need host driver to notify us.
             */
            mvotg->otg_ctrl.b_conn = 0;
            mv_otg_set_vbus(otg, 0);
            break;
        case OTG_STATE_A_VBUS_ERR:
            break;
        default:
            break;
        }
        goto run;
    }
}

static irqreturn_t mv_otg_irq(int irq, void *dev)
{
    struct mv_otg *mvotg = dev;
    u32 otgsc;

    otgsc = readl(&mvotg->op_regs->otgsc);
    writel(otgsc, &mvotg->op_regs->otgsc);

    /*
     * if we have vbus, then the vbus detection for B-device
     * will be done by mv_otg_inputs_irq().
     */
    if (mvotg->pdata->vbus)
        if ((otgsc & OTGSC_STS_USB_ID) &&
            !(otgsc & OTGSC_INTSTS_USB_ID))
            return IRQ_NONE;

    if ((otgsc & mvotg->irq_status) == 0)
        return IRQ_NONE;

    mv_otg_run_state_machine(mvotg, 0);

    return IRQ_HANDLED;
}

static irqreturn_t mv_otg_inputs_irq(int irq, void *dev)
{
    struct mv_otg *mvotg = dev;

    /* The clock may disabled at this time */
    if (!mvotg->active) {
        mv_otg_enable(mvotg);
        mv_otg_init_irq(mvotg);
    }

    mv_otg_run_state_machine(mvotg, 0);

    return IRQ_HANDLED;
}

static ssize_t
get_a_bus_req(struct device *dev, struct device_attribute *attr, char *buf)
{
    struct mv_otg *mvotg = dev_get_drvdata(dev);
    return scnprintf(buf, PAGE_SIZE, "%d\n",
             mvotg->otg_ctrl.a_bus_req);
}

static ssize_t
set_a_bus_req(struct device *dev, struct device_attribute *attr,
          const char *buf, size_t count)
{
    struct mv_otg *mvotg = dev_get_drvdata(dev);

    if (count > 2)
        return -1;

    /* We will use this interface to change to A device */
    if (mvotg->phy.state != OTG_STATE_B_IDLE
        && mvotg->phy.state != OTG_STATE_A_IDLE)
        return -1;

    /* The clock may disabled and we need to set irq for ID detected */
    mv_otg_enable(mvotg);
    mv_otg_init_irq(mvotg);

    if (buf[0] == '1') {
        mvotg->otg_ctrl.a_bus_req = 1;
        mvotg->otg_ctrl.a_bus_drop = 0;
        dev_dbg(&mvotg->pdev->dev,
            "User request: a_bus_req = 1\n");

        if (spin_trylock(&mvotg->wq_lock)) {
            mv_otg_run_state_machine(mvotg, 0);
            spin_unlock(&mvotg->wq_lock);
        }
    }

    return count;
}

static DEVICE_ATTR(a_bus_req, S_IRUGO | S_IWUSR, get_a_bus_req,
           set_a_bus_req);

static ssize_t
set_a_clr_err(struct device *dev, struct device_attribute *attr,
          const char *buf, size_t count)
{
    struct mv_otg *mvotg = dev_get_drvdata(dev);
    if (!mvotg->phy.otg->default_a)
        return -1;

    if (count > 2)
        return -1;

    if (buf[0] == '1') {
        mvotg->otg_ctrl.a_clr_err = 1;
        dev_dbg(&mvotg->pdev->dev,
            "User request: a_clr_err = 1\n");
    }

    if (spin_trylock(&mvotg->wq_lock)) {
        mv_otg_run_state_machine(mvotg, 0);
        spin_unlock(&mvotg->wq_lock);
    }

    return count;
}

static DEVICE_ATTR(a_clr_err, S_IWUSR, NULL, set_a_clr_err);

static ssize_t
get_a_bus_drop(struct device *dev, struct device_attribute *attr,
           char *buf)
{
    struct mv_otg *mvotg = dev_get_drvdata(dev);
    return scnprintf(buf, PAGE_SIZE, "%d\n",
             mvotg->otg_ctrl.a_bus_drop);
}

static ssize_t
set_a_bus_drop(struct device *dev, struct device_attribute *attr,
           const char *buf, size_t count)
{
    struct mv_otg *mvotg = dev_get_drvdata(dev);
    if (!mvotg->phy.otg->default_a)
        return -1;

    if (count > 2)
        return -1;

    if (buf[0] == '0') {
        mvotg->otg_ctrl.a_bus_drop = 0;
        dev_dbg(&mvotg->pdev->dev,
            "User request: a_bus_drop = 0\n");
    } else if (buf[0] == '1') {
        mvotg->otg_ctrl.a_bus_drop = 1;
        mvotg->otg_ctrl.a_bus_req = 0;
        dev_dbg(&mvotg->pdev->dev,
            "User request: a_bus_drop = 1\n");
        dev_dbg(&mvotg->pdev->dev,
            "User request: and a_bus_req = 0\n");
    }

    if (spin_trylock(&mvotg->wq_lock)) {
        mv_otg_run_state_machine(mvotg, 0);
        spin_unlock(&mvotg->wq_lock);
    }

    return count;
}

static DEVICE_ATTR(a_bus_drop, S_IRUGO | S_IWUSR,
           get_a_bus_drop, set_a_bus_drop);

static struct attribute *inputs_attrs[] = {
    &dev_attr_a_bus_req.attr,
    &dev_attr_a_clr_err.attr,
    &dev_attr_a_bus_drop.attr,
    NULL,
};

static struct attribute_group inputs_attr_group = {
    .name = "inputs",
    .attrs = inputs_attrs,
};

int mv_otg_remove(struct platform_device *pdev)
{
    struct mv_otg *mvotg = platform_get_drvdata(pdev);
    int clk_i;

    sysfs_remove_group(&mvotg->pdev->dev.kobj, &inputs_attr_group);

    if (mvotg->irq)
        free_irq(mvotg->irq, mvotg);

    if (mvotg->pdata->vbus)
        free_irq(mvotg->pdata->vbus->irq, mvotg);
    if (mvotg->pdata->id)
        free_irq(mvotg->pdata->id->irq, mvotg);

    if (mvotg->qwork) {
        flush_workqueue(mvotg->qwork);
        destroy_workqueue(mvotg->qwork);
    }

    mv_otg_disable(mvotg);

    if (mvotg->cap_regs)
        iounmap(mvotg->cap_regs);

    if (mvotg->phy_regs)
        iounmap(mvotg->phy_regs);

    for (clk_i = 0; clk_i <= mvotg->clknum; clk_i++)
        clk_put(mvotg->clk[clk_i]);

    usb_remove_phy(&mvotg->phy);
    platform_set_drvdata(pdev, NULL);

    kfree(mvotg->phy.otg);
    kfree(mvotg);

    return 0;
}

static int mv_otg_probe(struct platform_device *pdev)
{
    struct mv_usb_platform_data *pdata = pdev->dev.platform_data;
    struct mv_otg *mvotg;
    struct usb_otg *otg;
    struct resource *r;
    int retval = 0, clk_i, i;
    size_t size;

    if (pdata == NULL) {
        dev_err(&pdev->dev, "failed to get platform data\n");
        return -ENODEV;
    }

    size = sizeof(*mvotg) + sizeof(struct clk *) * pdata->clknum;
    mvotg = kzalloc(size, GFP_KERNEL);
    if (!mvotg) {
        dev_err(&pdev->dev, "failed to allocate memory!\n");
        return -ENOMEM;
    }

    otg = kzalloc(sizeof *otg, GFP_KERNEL);
    if (!otg) {
        kfree(mvotg);
        return -ENOMEM;
    }

    platform_set_drvdata(pdev, mvotg);

    mvotg->pdev = pdev;
    mvotg->pdata = pdata;

    mvotg->clknum = pdata->clknum;
    for (clk_i = 0; clk_i < mvotg->clknum; clk_i++) {
        mvotg->clk[clk_i] = clk_get(&pdev->dev, pdata->clkname[clk_i]);
        if (IS_ERR(mvotg->clk[clk_i])) {
            retval = PTR_ERR(mvotg->clk[clk_i]);
            goto err_put_clk;
        }
    }

    mvotg->qwork = create_singlethread_workqueue("mv_otg_queue");
    if (!mvotg->qwork) {
        dev_dbg(&pdev->dev, "cannot create workqueue for OTG\n");
        retval = -ENOMEM;
        goto err_put_clk;
    }

    INIT_DELAYED_WORK(&mvotg->work, mv_otg_work);

    /* OTG common part */
    mvotg->pdev = pdev;
    mvotg->phy.dev = &pdev->dev;
    mvotg->phy.otg = otg;
    mvotg->phy.label = driver_name;
    mvotg->phy.state = OTG_STATE_UNDEFINED;

    otg->phy = &mvotg->phy;
    otg->set_host = mv_otg_set_host;
    otg->set_peripheral = mv_otg_set_peripheral;
    otg->set_vbus = mv_otg_set_vbus;

    for (i = 0; i < OTG_TIMER_NUM; i++)
        init_timer(&mvotg->otg_ctrl.timer[i]);

    r = platform_get_resource_byname(mvotg->pdev,
                     IORESOURCE_MEM, "phyregs");
    if (r == NULL) {
        dev_err(&pdev->dev, "no phy I/O memory resource defined\n");
        retval = -ENODEV;
        goto err_destroy_workqueue;
    }

    mvotg->phy_regs = ioremap(r->start, resource_size(r));
    if (mvotg->phy_regs == NULL) {
        dev_err(&pdev->dev, "failed to map phy I/O memory\n");
        retval = -EFAULT;
        goto err_destroy_workqueue;
    }

    r = platform_get_resource_byname(mvotg->pdev,
                     IORESOURCE_MEM, "capregs");
    if (r == NULL) {
        dev_err(&pdev->dev, "no I/O memory resource defined\n");
        retval = -ENODEV;
        goto err_unmap_phyreg;
    }

    mvotg->cap_regs = ioremap(r->start, resource_size(r));
    if (mvotg->cap_regs == NULL) {
        dev_err(&pdev->dev, "failed to map I/O memory\n");
        retval = -EFAULT;
        goto err_unmap_phyreg;
    }

    /* we will acces controller register, so enable the udc controller */
    retval = mv_otg_enable_internal(mvotg);
    if (retval) {
        dev_err(&pdev->dev, "mv otg enable error %d\n", retval);
        goto err_unmap_capreg;
    }

    mvotg->op_regs =
        (struct mv_otg_regs __iomem *) ((unsigned long) mvotg->cap_regs
            + (readl(mvotg->cap_regs) & CAPLENGTH_MASK));

    if (pdata->id) {
        retval = request_threaded_irq(pdata->id->irq, NULL,
                          mv_otg_inputs_irq,
                          IRQF_ONESHOT, "id", mvotg);
        if (retval) {
            dev_info(&pdev->dev,
                 "Failed to request irq for ID\n");
            pdata->id = NULL;
        }
    }

    if (pdata->vbus) {
        mvotg->clock_gating = 1;
        retval = request_threaded_irq(pdata->vbus->irq, NULL,
                          mv_otg_inputs_irq,
                          IRQF_ONESHOT, "vbus", mvotg);
        if (retval) {
            dev_info(&pdev->dev,
                 "Failed to request irq for VBUS, "
                 "disable clock gating\n");
            mvotg->clock_gating = 0;
            pdata->vbus = NULL;
        }
    }

    if (pdata->disable_otg_clock_gating)
        mvotg->clock_gating = 0;

    mv_otg_reset(mvotg);
    mv_otg_init_irq(mvotg);

    r = platform_get_resource(mvotg->pdev, IORESOURCE_IRQ, 0);
    if (r == NULL) {
        dev_err(&pdev->dev, "no IRQ resource defined\n");
        retval = -ENODEV;
        goto err_disable_clk;
    }

    mvotg->irq = r->start;
    if (request_irq(mvotg->irq, mv_otg_irq, IRQF_SHARED,
            driver_name, mvotg)) {
        dev_err(&pdev->dev, "Request irq %d for OTG failed\n",
            mvotg->irq);
        mvotg->irq = 0;
        retval = -ENODEV;
        goto err_disable_clk;
    }

    retval = usb_add_phy(&mvotg->phy, USB_PHY_TYPE_USB2);
    if (retval < 0) {
        dev_err(&pdev->dev, "can't register transceiver, %d\n",
            retval);
        goto err_free_irq;
    }

    retval = sysfs_create_group(&pdev->dev.kobj, &inputs_attr_group);
    if (retval < 0) {
        dev_dbg(&pdev->dev,
            "Can't register sysfs attr group: %d\n", retval);
        goto err_set_transceiver;
    }

    spin_lock_init(&mvotg->wq_lock);
    if (spin_trylock(&mvotg->wq_lock)) {
        mv_otg_run_state_machine(mvotg, 2 * HZ);
        spin_unlock(&mvotg->wq_lock);
    }

    dev_info(&pdev->dev,
         "successful probe OTG device %s clock gating.\n",
         mvotg->clock_gating ? "with" : "without");

    return 0;

err_set_transceiver:
    usb_remove_phy(&mvotg->phy);
err_free_irq:
    free_irq(mvotg->irq, mvotg);
err_disable_clk:
    if (pdata->vbus)
        free_irq(pdata->vbus->irq, mvotg);
    if (pdata->id)
        free_irq(pdata->id->irq, mvotg);
    mv_otg_disable_internal(mvotg);
err_unmap_capreg:
    iounmap(mvotg->cap_regs);
err_unmap_phyreg:
    iounmap(mvotg->phy_regs);
err_destroy_workqueue:
    flush_workqueue(mvotg->qwork);
    destroy_workqueue(mvotg->qwork);
err_put_clk:
    for (clk_i--; clk_i >= 0; clk_i--)
        clk_put(mvotg->clk[clk_i]);

    platform_set_drvdata(pdev, NULL);
    kfree(otg);
    kfree(mvotg);

    return retval;
}

#ifdef CONFIG_PM
static int mv_otg_suspend(struct platform_device *pdev, pm_message_t state)
{
    struct mv_otg *mvotg = platform_get_drvdata(pdev);

    if (mvotg->phy.state != OTG_STATE_B_IDLE) {
        dev_info(&pdev->dev,
             "OTG state is not B_IDLE, it is %d!\n",
             mvotg->phy.state);
        return -EAGAIN;
    }

    if (!mvotg->clock_gating)
        mv_otg_disable_internal(mvotg);

    return 0;
}

static int mv_otg_resume(struct platform_device *pdev)
{
    struct mv_otg *mvotg = platform_get_drvdata(pdev);
    u32 otgsc;

    if (!mvotg->clock_gating) {
        mv_otg_enable_internal(mvotg);

        otgsc = readl(&mvotg->op_regs->otgsc);
        otgsc |= mvotg->irq_en;
        writel(otgsc, &mvotg->op_regs->otgsc);

        if (spin_trylock(&mvotg->wq_lock)) {
            mv_otg_run_state_machine(mvotg, 0);
            spin_unlock(&mvotg->wq_lock);
        }
    }
    return 0;
}
#endif

static struct platform_driver mv_otg_driver = {
    .probe = mv_otg_probe,
    .remove = __exit_p(mv_otg_remove),
    .driver = {
           .owner = THIS_MODULE,
           .name = driver_name,
           },
#ifdef CONFIG_PM
    .suspend = mv_otg_suspend,
    .resume = mv_otg_resume,
#endif
};

static int __init mv_otg_init(void)
{
    return platform_driver_register(&mv_otg_driver);
}

static void __exit mv_otg_exit(void)
{
    platform_driver_unregister(&mv_otg_driver);
}

module_init(mv_otg_init);
module_exit(mv_otg_exit);