/*
 * isp1301_omap - ISP 1301 USB transceiver, talking to OMAP OTG controller
 *
 * Copyright (C) 2004 Texas Instruments
 * Copyright (C) 2004 David Brownell
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb.h>
#include <linux/usb/otg.h>
#include <linux/i2c.h>
#include <linux/workqueue.h>

#include <asm/irq.h>
#include <asm/mach-types.h>

#include <mach/mux.h>

#include <mach/usb.h>

#undef VERBOSE


#define DRIVER_VERSION  "24 August 2004"
#define DRIVER_NAME     (isp1301_driver.driver.name)

MODULE_DESCRIPTION("ISP1301 USB OTG Transceiver Driver");
MODULE_LICENSE("GPL");

struct isp1301 {
        struct usb_phy          phy;
        struct i2c_client       *client;
        void                    (*i2c_release)(struct device *dev);

        int                     irq_type;

        u32                     last_otg_ctrl;
        unsigned                working:1;

        struct timer_list       timer;

        /* use keventd context to change the state for us */
        struct work_struct      work;

        unsigned long           todo;
#               define WORK_UPDATE_ISP  0       /* update ISP from OTG */
#               define WORK_UPDATE_OTG  1       /* update OTG from ISP */
#               define WORK_HOST_RESUME 4       /* resume host */
#               define WORK_TIMER       6       /* timer fired */
#               define WORK_STOP        7       /* don't resubmit */
};


/* bits in OTG_CTRL */

#define OTG_XCEIV_OUTPUTS \
        (OTG_ASESSVLD|OTG_BSESSEND|OTG_BSESSVLD|OTG_VBUSVLD|OTG_ID)
#define OTG_XCEIV_INPUTS \
        (OTG_PULLDOWN|OTG_PULLUP|OTG_DRV_VBUS|OTG_PD_VBUS|OTG_PU_VBUS|OTG_PU_ID)
#define OTG_CTRL_BITS \
        (OTG_A_BUSREQ|OTG_A_SETB_HNPEN|OTG_B_BUSREQ|OTG_B_HNPEN|OTG_BUSDROP)
        /* and OTG_PULLUP is sometimes written */

#define OTG_CTRL_MASK   (OTG_DRIVER_SEL| \
        OTG_XCEIV_OUTPUTS|OTG_XCEIV_INPUTS| \
        OTG_CTRL_BITS)


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

/* board-specific PM hooks */

#if defined(CONFIG_MACH_OMAP_H2) || defined(CONFIG_MACH_OMAP_H3)

#if     defined(CONFIG_TPS65010) || defined(CONFIG_TPS65010_MODULE)

#include <linux/i2c/tps65010.h>

#else

static inline int tps65010_set_vbus_draw(unsigned mA)
{
        pr_debug("tps65010: draw %d mA (STUB)\n", mA);
        return 0;
}

#endif

static void enable_vbus_draw(struct isp1301 *isp, unsigned mA)
{
        int status = tps65010_set_vbus_draw(mA);
        if (status < 0)
                pr_debug("  VBUS %d mA error %d\n", mA, status);
}

#else

static void enable_vbus_draw(struct isp1301 *isp, unsigned mA)
{
        /* H4 controls this by DIP switch S2.4; no soft control.
         * ON means the charger is always enabled.  Leave it OFF
         * unless the OTG port is used only in B-peripheral mode.
         */
}

#endif

static void enable_vbus_source(struct isp1301 *isp)
{
        /* this board won't supply more than 8mA vbus power.
         * some boards can switch a 100ma "unit load" (or more).
         */
}


/* products will deliver OTG messages with LEDs, GUI, etc */
static inline void notresponding(struct isp1301 *isp)
{
        printk(KERN_NOTICE "OTG device not responding.\n");
}


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

static struct i2c_driver isp1301_driver;

/* smbus apis are used for portability */

static inline u8
isp1301_get_u8(struct isp1301 *isp, u8 reg)
{
        return i2c_smbus_read_byte_data(isp->client, reg + 0);
}

static inline int
isp1301_get_u16(struct isp1301 *isp, u8 reg)
{
        return i2c_smbus_read_word_data(isp->client, reg);
}

static inline int
isp1301_set_bits(struct isp1301 *isp, u8 reg, u8 bits)
{
        return i2c_smbus_write_byte_data(isp->client, reg + 0, bits);
}

static inline int
isp1301_clear_bits(struct isp1301 *isp, u8 reg, u8 bits)
{
        return i2c_smbus_write_byte_data(isp->client, reg + 1, bits);
}

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

/* identification */
#define ISP1301_VENDOR_ID               0x00    /* u16 read */
#define ISP1301_PRODUCT_ID              0x02    /* u16 read */
#define ISP1301_BCD_DEVICE              0x14    /* u16 read */

#define I2C_VENDOR_ID_PHILIPS           0x04cc
#define I2C_PRODUCT_ID_PHILIPS_1301     0x1301

/* operational registers */
#define ISP1301_MODE_CONTROL_1          0x04    /* u8 read, set, +1 clear */
#       define  MC1_SPEED               (1 << 0)
#       define  MC1_SUSPEND             (1 << 1)
#       define  MC1_DAT_SE0             (1 << 2)
#       define  MC1_TRANSPARENT         (1 << 3)
#       define  MC1_BDIS_ACON_EN        (1 << 4)
#       define  MC1_OE_INT_EN           (1 << 5)
#       define  MC1_UART_EN             (1 << 6)
#       define  MC1_MASK                0x7f
#define ISP1301_MODE_CONTROL_2          0x12    /* u8 read, set, +1 clear */
#       define  MC2_GLOBAL_PWR_DN       (1 << 0)
#       define  MC2_SPD_SUSP_CTRL       (1 << 1)
#       define  MC2_BI_DI               (1 << 2)
#       define  MC2_TRANSP_BDIR0        (1 << 3)
#       define  MC2_TRANSP_BDIR1        (1 << 4)
#       define  MC2_AUDIO_EN            (1 << 5)
#       define  MC2_PSW_EN              (1 << 6)
#       define  MC2_EN2V7               (1 << 7)
#define ISP1301_OTG_CONTROL_1           0x06    /* u8 read, set, +1 clear */
#       define  OTG1_DP_PULLUP          (1 << 0)
#       define  OTG1_DM_PULLUP          (1 << 1)
#       define  OTG1_DP_PULLDOWN        (1 << 2)
#       define  OTG1_DM_PULLDOWN        (1 << 3)
#       define  OTG1_ID_PULLDOWN        (1 << 4)
#       define  OTG1_VBUS_DRV           (1 << 5)
#       define  OTG1_VBUS_DISCHRG       (1 << 6)
#       define  OTG1_VBUS_CHRG          (1 << 7)
#define ISP1301_OTG_STATUS              0x10    /* u8 readonly */
#       define  OTG_B_SESS_END          (1 << 6)
#       define  OTG_B_SESS_VLD          (1 << 7)

#define ISP1301_INTERRUPT_SOURCE        0x08    /* u8 read */
#define ISP1301_INTERRUPT_LATCH         0x0A    /* u8 read, set, +1 clear */

#define ISP1301_INTERRUPT_FALLING       0x0C    /* u8 read, set, +1 clear */
#define ISP1301_INTERRUPT_RISING        0x0E    /* u8 read, set, +1 clear */

/* same bitfields in all interrupt registers */
#       define  INTR_VBUS_VLD           (1 << 0)
#       define  INTR_SESS_VLD           (1 << 1)
#       define  INTR_DP_HI              (1 << 2)
#       define  INTR_ID_GND             (1 << 3)
#       define  INTR_DM_HI              (1 << 4)
#       define  INTR_ID_FLOAT           (1 << 5)
#       define  INTR_BDIS_ACON          (1 << 6)
#       define  INTR_CR_INT             (1 << 7)

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

static inline const char *state_name(struct isp1301 *isp)
{
        return usb_otg_state_string(isp->phy.state);
}

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

/* NOTE:  some of this ISP1301 setup is specific to H2 boards;
 * not everything is guarded by board-specific checks, or even using
 * omap_usb_config data to deduce MC1_DAT_SE0 and MC2_BI_DI.
 *
 * ALSO:  this currently doesn't use ISP1301 low-power modes
 * while OTG is running.
 */

static void power_down(struct isp1301 *isp)
{
        isp->phy.state = OTG_STATE_UNDEFINED;

        // isp1301_set_bits(isp, ISP1301_MODE_CONTROL_2, MC2_GLOBAL_PWR_DN);
        isp1301_set_bits(isp, ISP1301_MODE_CONTROL_1, MC1_SUSPEND);

        isp1301_clear_bits(isp, ISP1301_OTG_CONTROL_1, OTG1_ID_PULLDOWN);
        isp1301_clear_bits(isp, ISP1301_MODE_CONTROL_1, MC1_DAT_SE0);
}

static void power_up(struct isp1301 *isp)
{
        // isp1301_clear_bits(isp, ISP1301_MODE_CONTROL_2, MC2_GLOBAL_PWR_DN);
        isp1301_clear_bits(isp, ISP1301_MODE_CONTROL_1, MC1_SUSPEND);

        /* do this only when cpu is driving transceiver,
         * so host won't see a low speed device...
         */
        isp1301_set_bits(isp, ISP1301_MODE_CONTROL_1, MC1_DAT_SE0);
}

#define NO_HOST_SUSPEND

static int host_suspend(struct isp1301 *isp)
{
#ifdef  NO_HOST_SUSPEND
        return 0;
#else
        struct device   *dev;

        if (!isp->phy.otg->host)
                return -ENODEV;

        /* Currently ASSUMES only the OTG port matters;
         * other ports could be active...
         */
        dev = isp->phy.otg->host->controller;
        return dev->driver->suspend(dev, 3, 0);
#endif
}

static int host_resume(struct isp1301 *isp)
{
#ifdef  NO_HOST_SUSPEND
        return 0;
#else
        struct device   *dev;

        if (!isp->phy.otg->host)
                return -ENODEV;

        dev = isp->phy.otg->host->controller;
        return dev->driver->resume(dev, 0);
#endif
}

static int gadget_suspend(struct isp1301 *isp)
{
        isp->phy.otg->gadget->b_hnp_enable = 0;
        isp->phy.otg->gadget->a_hnp_support = 0;
        isp->phy.otg->gadget->a_alt_hnp_support = 0;
        return usb_gadget_vbus_disconnect(isp->phy.otg->gadget);
}

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

#define TIMER_MINUTES   10
#define TIMER_JIFFIES   (TIMER_MINUTES * 60 * HZ)

/* Almost all our I2C messaging comes from a work queue's task context.
 * NOTE: guaranteeing certain response times might mean we shouldn't
 * share keventd's work queue; a realtime task might be safest.
 */
static void isp1301_defer_work(struct isp1301 *isp, int work)
{
        int status;

        if (isp && !test_and_set_bit(work, &isp->todo)) {
                (void) get_device(&isp->client->dev);
                status = schedule_work(&isp->work);
                if (!status && !isp->working)
                        dev_vdbg(&isp->client->dev,
                                "work item %d may be lost\n", work);
        }
}

/* called from irq handlers */
static void a_idle(struct isp1301 *isp, const char *tag)
{
        u32 l;

        if (isp->phy.state == OTG_STATE_A_IDLE)
                return;

        isp->phy.otg->default_a = 1;
        if (isp->phy.otg->host) {
                isp->phy.otg->host->is_b_host = 0;
                host_suspend(isp);
        }
        if (isp->phy.otg->gadget) {
                isp->phy.otg->gadget->is_a_peripheral = 1;
                gadget_suspend(isp);
        }
        isp->phy.state = OTG_STATE_A_IDLE;
        l = omap_readl(OTG_CTRL) & OTG_XCEIV_OUTPUTS;
        omap_writel(l, OTG_CTRL);
        isp->last_otg_ctrl = l;
        pr_debug("  --> %s/%s\n", state_name(isp), tag);
}

/* called from irq handlers */
static void b_idle(struct isp1301 *isp, const char *tag)
{
        u32 l;

        if (isp->phy.state == OTG_STATE_B_IDLE)
                return;

        isp->phy.otg->default_a = 0;
        if (isp->phy.otg->host) {
                isp->phy.otg->host->is_b_host = 1;
                host_suspend(isp);
        }
        if (isp->phy.otg->gadget) {
                isp->phy.otg->gadget->is_a_peripheral = 0;
                gadget_suspend(isp);
        }
        isp->phy.state = OTG_STATE_B_IDLE;
        l = omap_readl(OTG_CTRL) & OTG_XCEIV_OUTPUTS;
        omap_writel(l, OTG_CTRL);
        isp->last_otg_ctrl = l;
        pr_debug("  --> %s/%s\n", state_name(isp), tag);
}

static void
dump_regs(struct isp1301 *isp, const char *label)
{
        u8      ctrl = isp1301_get_u8(isp, ISP1301_OTG_CONTROL_1);
        u8      status = isp1301_get_u8(isp, ISP1301_OTG_STATUS);
        u8      src = isp1301_get_u8(isp, ISP1301_INTERRUPT_SOURCE);

        pr_debug("otg: %06x, %s %s, otg/%02x stat/%02x.%02x\n",
                omap_readl(OTG_CTRL), label, state_name(isp),
                ctrl, status, src);
        /* mode control and irq enables don't change much */
}

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

#ifdef  CONFIG_USB_OTG

/*
 * The OMAP OTG controller handles most of the OTG state transitions.
 *
 * We translate isp1301 outputs (mostly voltage comparator status) into
 * OTG inputs; OTG outputs (mostly pullup/pulldown controls) and HNP state
 * flags into isp1301 inputs ... and infer state transitions.
 */

#ifdef  VERBOSE

static void check_state(struct isp1301 *isp, const char *tag)
{
        enum usb_otg_state      state = OTG_STATE_UNDEFINED;
        u8                      fsm = omap_readw(OTG_TEST) & 0x0ff;
        unsigned                extra = 0;

        switch (fsm) {

        /* default-b */
        case 0x0:
                state = OTG_STATE_B_IDLE;
                break;
        case 0x3:
        case 0x7:
                extra = 1;
        case 0x1:
                state = OTG_STATE_B_PERIPHERAL;
                break;
        case 0x11:
                state = OTG_STATE_B_SRP_INIT;
                break;

        /* extra dual-role default-b states */
        case 0x12:
        case 0x13:
        case 0x16:
                extra = 1;
        case 0x17:
                state = OTG_STATE_B_WAIT_ACON;
                break;
        case 0x34:
                state = OTG_STATE_B_HOST;
                break;

        /* default-a */
        case 0x36:
                state = OTG_STATE_A_IDLE;
                break;
        case 0x3c:
                state = OTG_STATE_A_WAIT_VFALL;
                break;
        case 0x7d:
                state = OTG_STATE_A_VBUS_ERR;
                break;
        case 0x9e:
        case 0x9f:
                extra = 1;
        case 0x89:
                state = OTG_STATE_A_PERIPHERAL;
                break;
        case 0xb7:
                state = OTG_STATE_A_WAIT_VRISE;
                break;
        case 0xb8:
                state = OTG_STATE_A_WAIT_BCON;
                break;
        case 0xb9:
                state = OTG_STATE_A_HOST;
                break;
        case 0xba:
                state = OTG_STATE_A_SUSPEND;
                break;
        default:
                break;
        }
        if (isp->phy.state == state && !extra)
                return;
        pr_debug("otg: %s FSM %s/%02x, %s, %06x\n", tag,
                usb_otg_state_string(state), fsm, state_name(isp),
                omap_readl(OTG_CTRL));
}

#else

static inline void check_state(struct isp1301 *isp, const char *tag) { }

#endif

/* outputs from ISP1301_INTERRUPT_SOURCE */
static void update_otg1(struct isp1301 *isp, u8 int_src)
{
        u32     otg_ctrl;

        otg_ctrl = omap_readl(OTG_CTRL) & OTG_CTRL_MASK;
        otg_ctrl &= ~OTG_XCEIV_INPUTS;
        otg_ctrl &= ~(OTG_ID|OTG_ASESSVLD|OTG_VBUSVLD);

        if (int_src & INTR_SESS_VLD)
                otg_ctrl |= OTG_ASESSVLD;
        else if (isp->phy.state == OTG_STATE_A_WAIT_VFALL) {
                a_idle(isp, "vfall");
                otg_ctrl &= ~OTG_CTRL_BITS;
        }
        if (int_src & INTR_VBUS_VLD)
                otg_ctrl |= OTG_VBUSVLD;
        if (int_src & INTR_ID_GND) {            /* default-A */
                if (isp->phy.state == OTG_STATE_B_IDLE
                                || isp->phy.state
                                        == OTG_STATE_UNDEFINED) {
                        a_idle(isp, "init");
                        return;
                }
        } else {                                /* default-B */
                otg_ctrl |= OTG_ID;
                if (isp->phy.state == OTG_STATE_A_IDLE
                        || isp->phy.state == OTG_STATE_UNDEFINED) {
                        b_idle(isp, "init");
                        return;
                }
        }
        omap_writel(otg_ctrl, OTG_CTRL);
}

/* outputs from ISP1301_OTG_STATUS */
static void update_otg2(struct isp1301 *isp, u8 otg_status)
{
        u32     otg_ctrl;

        otg_ctrl = omap_readl(OTG_CTRL) & OTG_CTRL_MASK;
        otg_ctrl &= ~OTG_XCEIV_INPUTS;
        otg_ctrl &= ~(OTG_BSESSVLD | OTG_BSESSEND);
        if (otg_status & OTG_B_SESS_VLD)
                otg_ctrl |= OTG_BSESSVLD;
        else if (otg_status & OTG_B_SESS_END)
                otg_ctrl |= OTG_BSESSEND;
        omap_writel(otg_ctrl, OTG_CTRL);
}

/* inputs going to ISP1301 */
static void otg_update_isp(struct isp1301 *isp)
{
        u32     otg_ctrl, otg_change;
        u8      set = OTG1_DM_PULLDOWN, clr = OTG1_DM_PULLUP;

        otg_ctrl = omap_readl(OTG_CTRL);
        otg_change = otg_ctrl ^ isp->last_otg_ctrl;
        isp->last_otg_ctrl = otg_ctrl;
        otg_ctrl = otg_ctrl & OTG_XCEIV_INPUTS;

        switch (isp->phy.state) {
        case OTG_STATE_B_IDLE:
        case OTG_STATE_B_PERIPHERAL:
        case OTG_STATE_B_SRP_INIT:
                if (!(otg_ctrl & OTG_PULLUP)) {
                        // if (otg_ctrl & OTG_B_HNPEN) {
                        if (isp->phy.otg->gadget->b_hnp_enable) {
                                isp->phy.state = OTG_STATE_B_WAIT_ACON;
                                pr_debug("  --> b_wait_acon\n");
                        }
                        goto pulldown;
                }
pullup:
                set |= OTG1_DP_PULLUP;
                clr |= OTG1_DP_PULLDOWN;
                break;
        case OTG_STATE_A_SUSPEND:
        case OTG_STATE_A_PERIPHERAL:
                if (otg_ctrl & OTG_PULLUP)
                        goto pullup;
                /* FALLTHROUGH */
        // case OTG_STATE_B_WAIT_ACON:
        default:
pulldown:
                set |= OTG1_DP_PULLDOWN;
                clr |= OTG1_DP_PULLUP;
                break;
        }

#       define toggle(OTG,ISP) do { \
                if (otg_ctrl & OTG) set |= ISP; \
                else clr |= ISP; \
                } while (0)

        if (!(isp->phy.otg->host))
                otg_ctrl &= ~OTG_DRV_VBUS;

        switch (isp->phy.state) {
        case OTG_STATE_A_SUSPEND:
                if (otg_ctrl & OTG_DRV_VBUS) {
                        set |= OTG1_VBUS_DRV;
                        break;
                }
                /* HNP failed for some reason (A_AIDL_BDIS timeout) */
                notresponding(isp);

                /* FALLTHROUGH */
        case OTG_STATE_A_VBUS_ERR:
                isp->phy.state = OTG_STATE_A_WAIT_VFALL;
                pr_debug("  --> a_wait_vfall\n");
                /* FALLTHROUGH */
        case OTG_STATE_A_WAIT_VFALL:
                /* FIXME usbcore thinks port power is still on ... */
                clr |= OTG1_VBUS_DRV;
                break;
        case OTG_STATE_A_IDLE:
                if (otg_ctrl & OTG_DRV_VBUS) {
                        isp->phy.state = OTG_STATE_A_WAIT_VRISE;
                        pr_debug("  --> a_wait_vrise\n");
                }
                /* FALLTHROUGH */
        default:
                toggle(OTG_DRV_VBUS, OTG1_VBUS_DRV);
        }

        toggle(OTG_PU_VBUS, OTG1_VBUS_CHRG);
        toggle(OTG_PD_VBUS, OTG1_VBUS_DISCHRG);

#       undef toggle

        isp1301_set_bits(isp, ISP1301_OTG_CONTROL_1, set);
        isp1301_clear_bits(isp, ISP1301_OTG_CONTROL_1, clr);

        /* HNP switch to host or peripheral; and SRP */
        if (otg_change & OTG_PULLUP) {
                u32 l;

                switch (isp->phy.state) {
                case OTG_STATE_B_IDLE:
                        if (clr & OTG1_DP_PULLUP)
                                break;
                        isp->phy.state = OTG_STATE_B_PERIPHERAL;
                        pr_debug("  --> b_peripheral\n");
                        break;
                case OTG_STATE_A_SUSPEND:
                        if (clr & OTG1_DP_PULLUP)
                                break;
                        isp->phy.state = OTG_STATE_A_PERIPHERAL;
                        pr_debug("  --> a_peripheral\n");
                        break;
                default:
                        break;
                }
                l = omap_readl(OTG_CTRL);
                l |= OTG_PULLUP;
                omap_writel(l, OTG_CTRL);
        }

        check_state(isp, __func__);
        dump_regs(isp, "otg->isp1301");
}

static irqreturn_t omap_otg_irq(int irq, void *_isp)
{
        u16             otg_irq = omap_readw(OTG_IRQ_SRC);
        u32             otg_ctrl;
        int             ret = IRQ_NONE;
        struct isp1301  *isp = _isp;
        struct usb_otg  *otg = isp->phy.otg;

        /* update ISP1301 transceiver from OTG controller */
        if (otg_irq & OPRT_CHG) {
                omap_writew(OPRT_CHG, OTG_IRQ_SRC);
                isp1301_defer_work(isp, WORK_UPDATE_ISP);
                ret = IRQ_HANDLED;

        /* SRP to become b_peripheral failed */
        } else if (otg_irq & B_SRP_TMROUT) {
                pr_debug("otg: B_SRP_TIMEOUT, %06x\n", omap_readl(OTG_CTRL));
                notresponding(isp);

                /* gadget drivers that care should monitor all kinds of
                 * remote wakeup (SRP, normal) using their own timer
                 * to give "check cable and A-device" messages.
                 */
                if (isp->phy.state == OTG_STATE_B_SRP_INIT)
                        b_idle(isp, "srp_timeout");

                omap_writew(B_SRP_TMROUT, OTG_IRQ_SRC);
                ret = IRQ_HANDLED;

        /* HNP to become b_host failed */
        } else if (otg_irq & B_HNP_FAIL) {
                pr_debug("otg: %s B_HNP_FAIL, %06x\n",
                                state_name(isp), omap_readl(OTG_CTRL));
                notresponding(isp);

                otg_ctrl = omap_readl(OTG_CTRL);
                otg_ctrl |= OTG_BUSDROP;
                otg_ctrl &= OTG_CTRL_MASK & ~OTG_XCEIV_INPUTS;
                omap_writel(otg_ctrl, OTG_CTRL);

                /* subset of b_peripheral()... */
                isp->phy.state = OTG_STATE_B_PERIPHERAL;
                pr_debug("  --> b_peripheral\n");

                omap_writew(B_HNP_FAIL, OTG_IRQ_SRC);
                ret = IRQ_HANDLED;

        /* detect SRP from B-device ... */
        } else if (otg_irq & A_SRP_DETECT) {
                pr_debug("otg: %s SRP_DETECT, %06x\n",
                                state_name(isp), omap_readl(OTG_CTRL));

                isp1301_defer_work(isp, WORK_UPDATE_OTG);
                switch (isp->phy.state) {
                case OTG_STATE_A_IDLE:
                        if (!otg->host)
                                break;
                        isp1301_defer_work(isp, WORK_HOST_RESUME);
                        otg_ctrl = omap_readl(OTG_CTRL);
                        otg_ctrl |= OTG_A_BUSREQ;
                        otg_ctrl &= ~(OTG_BUSDROP|OTG_B_BUSREQ)
                                        & ~OTG_XCEIV_INPUTS
                                        & OTG_CTRL_MASK;
                        omap_writel(otg_ctrl, OTG_CTRL);
                        break;
                default:
                        break;
                }

                omap_writew(A_SRP_DETECT, OTG_IRQ_SRC);
                ret = IRQ_HANDLED;

        /* timer expired:  T(a_wait_bcon) and maybe T(a_wait_vrise)
         * we don't track them separately
         */
        } else if (otg_irq & A_REQ_TMROUT) {
                otg_ctrl = omap_readl(OTG_CTRL);
                pr_info("otg: BCON_TMOUT from %s, %06x\n",
                                state_name(isp), otg_ctrl);
                notresponding(isp);

                otg_ctrl |= OTG_BUSDROP;
                otg_ctrl &= ~OTG_A_BUSREQ & OTG_CTRL_MASK & ~OTG_XCEIV_INPUTS;
                omap_writel(otg_ctrl, OTG_CTRL);
                isp->phy.state = OTG_STATE_A_WAIT_VFALL;

                omap_writew(A_REQ_TMROUT, OTG_IRQ_SRC);
                ret = IRQ_HANDLED;

        /* A-supplied voltage fell too low; overcurrent */
        } else if (otg_irq & A_VBUS_ERR) {
                otg_ctrl = omap_readl(OTG_CTRL);
                printk(KERN_ERR "otg: %s, VBUS_ERR %04x ctrl %06x\n",
                        state_name(isp), otg_irq, otg_ctrl);

                otg_ctrl |= OTG_BUSDROP;
                otg_ctrl &= ~OTG_A_BUSREQ & OTG_CTRL_MASK & ~OTG_XCEIV_INPUTS;
                omap_writel(otg_ctrl, OTG_CTRL);
                isp->phy.state = OTG_STATE_A_VBUS_ERR;

                omap_writew(A_VBUS_ERR, OTG_IRQ_SRC);
                ret = IRQ_HANDLED;

        /* switch driver; the transceiver code activates it,
         * ungating the udc clock or resuming OHCI.
         */
        } else if (otg_irq & DRIVER_SWITCH) {
                int     kick = 0;

                otg_ctrl = omap_readl(OTG_CTRL);
                printk(KERN_NOTICE "otg: %s, SWITCH to %s, ctrl %06x\n",
                                state_name(isp),
                                (otg_ctrl & OTG_DRIVER_SEL)
                                        ? "gadget" : "host",
                                otg_ctrl);
                isp1301_defer_work(isp, WORK_UPDATE_ISP);

                /* role is peripheral */
                if (otg_ctrl & OTG_DRIVER_SEL) {
                        switch (isp->phy.state) {
                        case OTG_STATE_A_IDLE:
                                b_idle(isp, __func__);
                                break;
                        default:
                                break;
                        }
                        isp1301_defer_work(isp, WORK_UPDATE_ISP);

                /* role is host */
                } else {
                        if (!(otg_ctrl & OTG_ID)) {
                                otg_ctrl &= OTG_CTRL_MASK & ~OTG_XCEIV_INPUTS;
                                omap_writel(otg_ctrl | OTG_A_BUSREQ, OTG_CTRL);
                        }

                        if (otg->host) {
                                switch (isp->phy.state) {
                                case OTG_STATE_B_WAIT_ACON:
                                        isp->phy.state = OTG_STATE_B_HOST;
                                        pr_debug("  --> b_host\n");
                                        kick = 1;
                                        break;
                                case OTG_STATE_A_WAIT_BCON:
                                        isp->phy.state = OTG_STATE_A_HOST;
                                        pr_debug("  --> a_host\n");
                                        break;
                                case OTG_STATE_A_PERIPHERAL:
                                        isp->phy.state = OTG_STATE_A_WAIT_BCON;
                                        pr_debug("  --> a_wait_bcon\n");
                                        break;
                                default:
                                        break;
                                }
                                isp1301_defer_work(isp, WORK_HOST_RESUME);
                        }
                }

                omap_writew(DRIVER_SWITCH, OTG_IRQ_SRC);
                ret = IRQ_HANDLED;

                if (kick)
                        usb_bus_start_enum(otg->host, otg->host->otg_port);
        }

        check_state(isp, __func__);
        return ret;
}

static struct platform_device *otg_dev;

static int isp1301_otg_init(struct isp1301 *isp)
{
        u32 l;

        if (!otg_dev)
                return -ENODEV;

        dump_regs(isp, __func__);
        /* some of these values are board-specific... */
        l = omap_readl(OTG_SYSCON_2);
        l |= OTG_EN
                /* for B-device: */
                | SRP_GPDATA            /* 9msec Bdev D+ pulse */
                | SRP_GPDVBUS           /* discharge after VBUS pulse */
                // | (3 << 24)          /* 2msec VBUS pulse */
                /* for A-device: */
                | (0 << 20)             /* 200ms nominal A_WAIT_VRISE timer */
                | SRP_DPW               /* detect 167+ns SRP pulses */
                | SRP_DATA | SRP_VBUS   /* accept both kinds of SRP pulse */
                ;
        omap_writel(l, OTG_SYSCON_2);

        update_otg1(isp, isp1301_get_u8(isp, ISP1301_INTERRUPT_SOURCE));
        update_otg2(isp, isp1301_get_u8(isp, ISP1301_OTG_STATUS));

        check_state(isp, __func__);
        pr_debug("otg: %s, %s %06x\n",
                        state_name(isp), __func__, omap_readl(OTG_CTRL));

        omap_writew(DRIVER_SWITCH | OPRT_CHG
                        | B_SRP_TMROUT | B_HNP_FAIL
                        | A_VBUS_ERR | A_SRP_DETECT | A_REQ_TMROUT, OTG_IRQ_EN);

        l = omap_readl(OTG_SYSCON_2);
        l |= OTG_EN;
        omap_writel(l, OTG_SYSCON_2);

        return 0;
}

static int otg_probe(struct platform_device *dev)
{
        // struct omap_usb_config *config = dev->platform_data;

        otg_dev = dev;
        return 0;
}

static int otg_remove(struct platform_device *dev)
{
        otg_dev = NULL;
        return 0;
}

static struct platform_driver omap_otg_driver = {
        .probe          = otg_probe,
        .remove         = otg_remove,
        .driver         = {
                .owner  = THIS_MODULE,
                .name   = "omap_otg",
        },
};

static int otg_bind(struct isp1301 *isp)
{
        int     status;

        if (otg_dev)
                return -EBUSY;

        status = platform_driver_register(&omap_otg_driver);
        if (status < 0)
                return status;

        if (otg_dev)
                status = request_irq(otg_dev->resource[1].start, omap_otg_irq,
                                0, DRIVER_NAME, isp);
        else
                status = -ENODEV;

        if (status < 0)
                platform_driver_unregister(&omap_otg_driver);
        return status;
}

static void otg_unbind(struct isp1301 *isp)
{
        if (!otg_dev)
                return;
        free_irq(otg_dev->resource[1].start, isp);
}

#else

/* OTG controller isn't clocked */

#endif  /* CONFIG_USB_OTG */

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

static void b_peripheral(struct isp1301 *isp)
{
        u32 l;

        l = omap_readl(OTG_CTRL) & OTG_XCEIV_OUTPUTS;
        omap_writel(l, OTG_CTRL);

        usb_gadget_vbus_connect(isp->phy.otg->gadget);

#ifdef  CONFIG_USB_OTG
        enable_vbus_draw(isp, 8);
        otg_update_isp(isp);
#else
        enable_vbus_draw(isp, 100);
        /* UDC driver just set OTG_BSESSVLD */
        isp1301_set_bits(isp, ISP1301_OTG_CONTROL_1, OTG1_DP_PULLUP);
        isp1301_clear_bits(isp, ISP1301_OTG_CONTROL_1, OTG1_DP_PULLDOWN);
        isp->phy.state = OTG_STATE_B_PERIPHERAL;
        pr_debug("  --> b_peripheral\n");
        dump_regs(isp, "2periph");
#endif
}

static void isp_update_otg(struct isp1301 *isp, u8 stat)
{
        struct usb_otg          *otg = isp->phy.otg;
        u8                      isp_stat, isp_bstat;
        enum usb_otg_state      state = isp->phy.state;

        if (stat & INTR_BDIS_ACON)
                pr_debug("OTG:  BDIS_ACON, %s\n", state_name(isp));

        /* start certain state transitions right away */
        isp_stat = isp1301_get_u8(isp, ISP1301_INTERRUPT_SOURCE);
        if (isp_stat & INTR_ID_GND) {
                if (otg->default_a) {
                        switch (state) {
                        case OTG_STATE_B_IDLE:
                                a_idle(isp, "idle");
                                /* FALLTHROUGH */
                        case OTG_STATE_A_IDLE:
                                enable_vbus_source(isp);
                                /* FALLTHROUGH */
                        case OTG_STATE_A_WAIT_VRISE:
                                /* we skip over OTG_STATE_A_WAIT_BCON, since
                                 * the HC will transition to A_HOST (or
                                 * A_SUSPEND!) without our noticing except
                                 * when HNP is used.
                                 */
                                if (isp_stat & INTR_VBUS_VLD)
                                        isp->phy.state = OTG_STATE_A_HOST;
                                break;
                        case OTG_STATE_A_WAIT_VFALL:
                                if (!(isp_stat & INTR_SESS_VLD))
                                        a_idle(isp, "vfell");
                                break;
                        default:
                                if (!(isp_stat & INTR_VBUS_VLD))
                                        isp->phy.state = OTG_STATE_A_VBUS_ERR;
                                break;
                        }
                        isp_bstat = isp1301_get_u8(isp, ISP1301_OTG_STATUS);
                } else {
                        switch (state) {
                        case OTG_STATE_B_PERIPHERAL:
                        case OTG_STATE_B_HOST:
                        case OTG_STATE_B_WAIT_ACON:
                                usb_gadget_vbus_disconnect(otg->gadget);
                                break;
                        default:
                                break;
                        }
                        if (state != OTG_STATE_A_IDLE)
                                a_idle(isp, "id");
                        if (otg->host && state == OTG_STATE_A_IDLE)
                                isp1301_defer_work(isp, WORK_HOST_RESUME);
                        isp_bstat = 0;
                }

        } else {
                u32 l;

                /* if user unplugged mini-A end of cable,
                 * don't bypass A_WAIT_VFALL.
                 */
                if (otg->default_a) {
                        switch (state) {
                        default:
                                isp->phy.state = OTG_STATE_A_WAIT_VFALL;
                                break;
                        case OTG_STATE_A_WAIT_VFALL:
                                state = OTG_STATE_A_IDLE;
                                /* khubd may take a while to notice and
                                 * handle this disconnect, so don't go
                                 * to B_IDLE quite yet.
                                 */
                                break;
                        case OTG_STATE_A_IDLE:
                                host_suspend(isp);
                                isp1301_clear_bits(isp, ISP1301_MODE_CONTROL_1,
                                                MC1_BDIS_ACON_EN);
                                isp->phy.state = OTG_STATE_B_IDLE;
                                l = omap_readl(OTG_CTRL) & OTG_CTRL_MASK;
                                l &= ~OTG_CTRL_BITS;
                                omap_writel(l, OTG_CTRL);
                                break;
                        case OTG_STATE_B_IDLE:
                                break;
                        }
                }
                isp_bstat = isp1301_get_u8(isp, ISP1301_OTG_STATUS);

                switch (isp->phy.state) {
                case OTG_STATE_B_PERIPHERAL:
                case OTG_STATE_B_WAIT_ACON:
                case OTG_STATE_B_HOST:
                        if (likely(isp_bstat & OTG_B_SESS_VLD))
                                break;
                        enable_vbus_draw(isp, 0);
#ifndef CONFIG_USB_OTG
                        /* UDC driver will clear OTG_BSESSVLD */
                        isp1301_set_bits(isp, ISP1301_OTG_CONTROL_1,
                                                OTG1_DP_PULLDOWN);
                        isp1301_clear_bits(isp, ISP1301_OTG_CONTROL_1,
                                                OTG1_DP_PULLUP);
                        dump_regs(isp, __func__);
#endif
                        /* FALLTHROUGH */
                case OTG_STATE_B_SRP_INIT:
                        b_idle(isp, __func__);
                        l = omap_readl(OTG_CTRL) & OTG_XCEIV_OUTPUTS;
                        omap_writel(l, OTG_CTRL);
                        /* FALLTHROUGH */
                case OTG_STATE_B_IDLE:
                        if (otg->gadget && (isp_bstat & OTG_B_SESS_VLD)) {
#ifdef  CONFIG_USB_OTG
                                update_otg1(isp, isp_stat);
                                update_otg2(isp, isp_bstat);
#endif
                                b_peripheral(isp);
                        } else if (!(isp_stat & (INTR_VBUS_VLD|INTR_SESS_VLD)))
                                isp_bstat |= OTG_B_SESS_END;
                        break;
                case OTG_STATE_A_WAIT_VFALL:
                        break;
                default:
                        pr_debug("otg: unsupported b-device %s\n",
                                state_name(isp));
                        break;
                }
        }

        if (state != isp->phy.state)
                pr_debug("  isp, %s -> %s\n",
                                usb_otg_state_string(state), state_name(isp));

#ifdef  CONFIG_USB_OTG
        /* update the OTG controller state to match the isp1301; may
         * trigger OPRT_CHG irqs for changes going to the isp1301.
         */
        update_otg1(isp, isp_stat);
        update_otg2(isp, isp_bstat);
        check_state(isp, __func__);
#endif

        dump_regs(isp, "isp1301->otg");
}

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

static u8 isp1301_clear_latch(struct isp1301 *isp)
{
        u8 latch = isp1301_get_u8(isp, ISP1301_INTERRUPT_LATCH);
        isp1301_clear_bits(isp, ISP1301_INTERRUPT_LATCH, latch);
        return latch;
}

static void
isp1301_work(struct work_struct *work)
{
        struct isp1301  *isp = container_of(work, struct isp1301, work);
        int             stop;

        /* implicit lock:  we're the only task using this device */
        isp->working = 1;
        do {
                stop = test_bit(WORK_STOP, &isp->todo);

#ifdef  CONFIG_USB_OTG
                /* transfer state from otg engine to isp1301 */
                if (test_and_clear_bit(WORK_UPDATE_ISP, &isp->todo)) {
                        otg_update_isp(isp);
                        put_device(&isp->client->dev);
                }
#endif
                /* transfer state from isp1301 to otg engine */
                if (test_and_clear_bit(WORK_UPDATE_OTG, &isp->todo)) {
                        u8              stat = isp1301_clear_latch(isp);

                        isp_update_otg(isp, stat);
                        put_device(&isp->client->dev);
                }

                if (test_and_clear_bit(WORK_HOST_RESUME, &isp->todo)) {
                        u32     otg_ctrl;

                        /*
                         * skip A_WAIT_VRISE; hc transitions invisibly
                         * skip A_WAIT_BCON; same.
                         */
                        switch (isp->phy.state) {
                        case OTG_STATE_A_WAIT_BCON:
                        case OTG_STATE_A_WAIT_VRISE:
                                isp->phy.state = OTG_STATE_A_HOST;
                                pr_debug("  --> a_host\n");
                                otg_ctrl = omap_readl(OTG_CTRL);
                                otg_ctrl |= OTG_A_BUSREQ;
                                otg_ctrl &= ~(OTG_BUSDROP|OTG_B_BUSREQ)
                                                & OTG_CTRL_MASK;
                                omap_writel(otg_ctrl, OTG_CTRL);
                                break;
                        case OTG_STATE_B_WAIT_ACON:
                                isp->phy.state = OTG_STATE_B_HOST;
                                pr_debug("  --> b_host (acon)\n");
                                break;
                        case OTG_STATE_B_HOST:
                        case OTG_STATE_B_IDLE:
                        case OTG_STATE_A_IDLE:
                                break;
                        default:
                                pr_debug("  host resume in %s\n",
                                                state_name(isp));
                        }
                        host_resume(isp);
                        // mdelay(10);
                        put_device(&isp->client->dev);
                }

                if (test_and_clear_bit(WORK_TIMER, &isp->todo)) {
#ifdef  VERBOSE
                        dump_regs(isp, "timer");
                        if (!stop)
                                mod_timer(&isp->timer, jiffies + TIMER_JIFFIES);
#endif
                        put_device(&isp->client->dev);
                }

                if (isp->todo)
                        dev_vdbg(&isp->client->dev,
                                "work done, todo = 0x%lx\n",
                                isp->todo);
                if (stop) {
                        dev_dbg(&isp->client->dev, "stop\n");
                        break;
                }
        } while (isp->todo);
        isp->working = 0;
}

static irqreturn_t isp1301_irq(int irq, void *isp)
{
        isp1301_defer_work(isp, WORK_UPDATE_OTG);
        return IRQ_HANDLED;
}

static void isp1301_timer(unsigned long _isp)
{
        isp1301_defer_work((void *)_isp, WORK_TIMER);
}

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

static void isp1301_release(struct device *dev)
{
        struct isp1301  *isp;

        isp = dev_get_drvdata(dev);

        /* FIXME -- not with a "new style" driver, it doesn't!! */

        /* ugly -- i2c hijacks our memory hook to wait_for_completion() */
        if (isp->i2c_release)
                isp->i2c_release(dev);
        kfree(isp->phy.otg);
        kfree (isp);
}

static struct isp1301 *the_transceiver;

static int isp1301_remove(struct i2c_client *i2c)
{
        struct isp1301  *isp;

        isp = i2c_get_clientdata(i2c);

        isp1301_clear_bits(isp, ISP1301_INTERRUPT_FALLING, ~0);
        isp1301_clear_bits(isp, ISP1301_INTERRUPT_RISING, ~0);
        free_irq(i2c->irq, isp);
#ifdef  CONFIG_USB_OTG
        otg_unbind(isp);
#endif
        if (machine_is_omap_h2())
                gpio_free(2);

        isp->timer.data = 0;
        set_bit(WORK_STOP, &isp->todo);
        del_timer_sync(&isp->timer);
        flush_work(&isp->work);

        put_device(&i2c->dev);
        the_transceiver = NULL;

        return 0;
}

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

/* NOTE:  three modes are possible here, only one of which
 * will be standards-conformant on any given system:
 *
 *  - OTG mode (dual-role), required if there's a Mini-AB connector
 *  - HOST mode, for when there's one or more A (host) connectors
 *  - DEVICE mode, for when there's a B/Mini-B (device) connector
 *
 * As a rule, you won't have an isp1301 chip unless it's there to
 * support the OTG mode.  Other modes help testing USB controllers
 * in isolation from (full) OTG support, or maybe so later board
 * revisions can help to support those feature.
 */

#ifdef  CONFIG_USB_OTG

static int isp1301_otg_enable(struct isp1301 *isp)
{
        power_up(isp);
        isp1301_otg_init(isp);

        /* NOTE:  since we don't change this, this provides
         * a few more interrupts than are strictly needed.
         */
        isp1301_set_bits(isp, ISP1301_INTERRUPT_RISING,
                INTR_VBUS_VLD | INTR_SESS_VLD | INTR_ID_GND);
        isp1301_set_bits(isp, ISP1301_INTERRUPT_FALLING,
                INTR_VBUS_VLD | INTR_SESS_VLD | INTR_ID_GND);

        dev_info(&isp->client->dev, "ready for dual-role USB ...\n");

        return 0;
}

#endif

/* add or disable the host device+driver */
static int
isp1301_set_host(struct usb_otg *otg, struct usb_bus *host)
{
        struct isp1301  *isp = container_of(otg->phy, struct isp1301, phy);

        if (isp != the_transceiver)
                return -ENODEV;

        if (!host) {
                omap_writew(0, OTG_IRQ_EN);
                power_down(isp);
                otg->host = NULL;
                return 0;
        }

#ifdef  CONFIG_USB_OTG
        otg->host = host;
        dev_dbg(&isp->client->dev, "registered host\n");
        host_suspend(isp);
        if (otg->gadget)
                return isp1301_otg_enable(isp);
        return 0;

#elif   !defined(CONFIG_USB_GADGET_OMAP)
        // FIXME update its refcount
        otg->host = host;

        power_up(isp);

        if (machine_is_omap_h2())
                isp1301_set_bits(isp, ISP1301_MODE_CONTROL_1, MC1_DAT_SE0);

        dev_info(&isp->client->dev, "A-Host sessions ok\n");
        isp1301_set_bits(isp, ISP1301_INTERRUPT_RISING,
                INTR_ID_GND);
        isp1301_set_bits(isp, ISP1301_INTERRUPT_FALLING,
                INTR_ID_GND);

        /* If this has a Mini-AB connector, this mode is highly
         * nonstandard ... but can be handy for testing, especially with
         * the Mini-A end of an OTG cable.  (Or something nonstandard
         * like MiniB-to-StandardB, maybe built with a gender mender.)
         */
        isp1301_set_bits(isp, ISP1301_OTG_CONTROL_1, OTG1_VBUS_DRV);

        dump_regs(isp, __func__);

        return 0;

#else
        dev_dbg(&isp->client->dev, "host sessions not allowed\n");
        return -EINVAL;
#endif

}

static int
isp1301_set_peripheral(struct usb_otg *otg, struct usb_gadget *gadget)
{
        struct isp1301  *isp = container_of(otg->phy, struct isp1301, phy);

        if (isp != the_transceiver)
                return -ENODEV;

        if (!gadget) {
                omap_writew(0, OTG_IRQ_EN);
                if (!otg->default_a)
                        enable_vbus_draw(isp, 0);
                usb_gadget_vbus_disconnect(otg->gadget);
                otg->gadget = NULL;
                power_down(isp);
                return 0;
        }

#ifdef  CONFIG_USB_OTG
        otg->gadget = gadget;
        dev_dbg(&isp->client->dev, "registered gadget\n");
        /* gadget driver may be suspended until vbus_connect () */
        if (otg->host)
                return isp1301_otg_enable(isp);
        return 0;

#elif   !defined(CONFIG_USB_OHCI_HCD) && !defined(CONFIG_USB_OHCI_HCD_MODULE)
        otg->gadget = gadget;
        // FIXME update its refcount

        {
                u32 l;

                l = omap_readl(OTG_CTRL) & OTG_CTRL_MASK;
                l &= ~(OTG_XCEIV_OUTPUTS|OTG_CTRL_BITS);
                l |= OTG_ID;
                omap_writel(l, OTG_CTRL);
        }

        power_up(isp);
        isp->phy.state = OTG_STATE_B_IDLE;

        if (machine_is_omap_h2() || machine_is_omap_h3())
                isp1301_set_bits(isp, ISP1301_MODE_CONTROL_1, MC1_DAT_SE0);

        isp1301_set_bits(isp, ISP1301_INTERRUPT_RISING,
                INTR_SESS_VLD);
        isp1301_set_bits(isp, ISP1301_INTERRUPT_FALLING,
                INTR_VBUS_VLD);
        dev_info(&isp->client->dev, "B-Peripheral sessions ok\n");
        dump_regs(isp, __func__);

        /* If this has a Mini-AB connector, this mode is highly
         * nonstandard ... but can be handy for testing, so long
         * as you don't plug a Mini-A cable into the jack.
         */
        if (isp1301_get_u8(isp, ISP1301_INTERRUPT_SOURCE) & INTR_VBUS_VLD)
                b_peripheral(isp);

        return 0;

#else
        dev_dbg(&isp->client->dev, "peripheral sessions not allowed\n");
        return -EINVAL;
#endif
}


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

static int
isp1301_set_power(struct usb_phy *dev, unsigned mA)
{
        if (!the_transceiver)
                return -ENODEV;
        if (dev->state == OTG_STATE_B_PERIPHERAL)
                enable_vbus_draw(the_transceiver, mA);
        return 0;
}

static int
isp1301_start_srp(struct usb_otg *otg)
{
        struct isp1301  *isp = container_of(otg->phy, struct isp1301, phy);
        u32             otg_ctrl;

        if (isp != the_transceiver || isp->phy.state != OTG_STATE_B_IDLE)
                return -ENODEV;

        otg_ctrl = omap_readl(OTG_CTRL);
        if (!(otg_ctrl & OTG_BSESSEND))
                return -EINVAL;

        otg_ctrl |= OTG_B_BUSREQ;
        otg_ctrl &= ~OTG_A_BUSREQ & OTG_CTRL_MASK;
        omap_writel(otg_ctrl, OTG_CTRL);
        isp->phy.state = OTG_STATE_B_SRP_INIT;

        pr_debug("otg: SRP, %s ... %06x\n", state_name(isp),
                        omap_readl(OTG_CTRL));
#ifdef  CONFIG_USB_OTG
        check_state(isp, __func__);
#endif
        return 0;
}

static int
isp1301_start_hnp(struct usb_otg *otg)
{
#ifdef  CONFIG_USB_OTG
        struct isp1301  *isp = container_of(otg->phy, struct isp1301, phy);
        u32 l;

        if (isp != the_transceiver)
                return -ENODEV;
        if (otg->default_a && (otg->host == NULL || !otg->host->b_hnp_enable))
                return -ENOTCONN;
        if (!otg->default_a && (otg->gadget == NULL
                        || !otg->gadget->b_hnp_enable))
                return -ENOTCONN;

        /* We want hardware to manage most HNP protocol timings.
         * So do this part as early as possible...
         */
        switch (isp->phy.state) {
        case OTG_STATE_B_HOST:
                isp->phy.state = OTG_STATE_B_PERIPHERAL;
                /* caller will suspend next */
                break;
        case OTG_STATE_A_HOST:
#if 0
                /* autoconnect mode avoids irq latency bugs */
                isp1301_set_bits(isp, ISP1301_MODE_CONTROL_1,
                                MC1_BDIS_ACON_EN);
#endif
                /* caller must suspend then clear A_BUSREQ */
                usb_gadget_vbus_connect(otg->gadget);
                l = omap_readl(OTG_CTRL);
                l |= OTG_A_SETB_HNPEN;
                omap_writel(l, OTG_CTRL);

                break;
        case OTG_STATE_A_PERIPHERAL:
                /* initiated by B-Host suspend */
                break;
        default:
                return -EILSEQ;
        }
        pr_debug("otg: HNP %s, %06x ...\n",
                state_name(isp), omap_readl(OTG_CTRL));
        check_state(isp, __func__);
        return 0;
#else
        /* srp-only */
        return -EINVAL;
#endif
}

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

static int
isp1301_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
{
        int                     status;
        struct isp1301          *isp;

        if (the_transceiver)
                return 0;

        isp = kzalloc(sizeof *isp, GFP_KERNEL);
        if (!isp)
                return 0;

        isp->phy.otg = kzalloc(sizeof *isp->phy.otg, GFP_KERNEL);
        if (!isp->phy.otg) {
                kfree(isp);
                return 0;
        }

        INIT_WORK(&isp->work, isp1301_work);
        init_timer(&isp->timer);
        isp->timer.function = isp1301_timer;
        isp->timer.data = (unsigned long) isp;

        i2c_set_clientdata(i2c, isp);
        isp->client = i2c;

        /* verify the chip (shouldn't be necessary) */
        status = isp1301_get_u16(isp, ISP1301_VENDOR_ID);
        if (status != I2C_VENDOR_ID_PHILIPS) {
                dev_dbg(&i2c->dev, "not philips id: %d\n", status);
                goto fail;
        }
        status = isp1301_get_u16(isp, ISP1301_PRODUCT_ID);
        if (status != I2C_PRODUCT_ID_PHILIPS_1301) {
                dev_dbg(&i2c->dev, "not isp1301, %d\n", status);
                goto fail;
        }
        isp->i2c_release = i2c->dev.release;
        i2c->dev.release = isp1301_release;

        /* initial development used chiprev 2.00 */
        status = i2c_smbus_read_word_data(i2c, ISP1301_BCD_DEVICE);
        dev_info(&i2c->dev, "chiprev %x.%02x, driver " DRIVER_VERSION "\n",
                status >> 8, status & 0xff);

        /* make like power-on reset */
        isp1301_clear_bits(isp, ISP1301_MODE_CONTROL_1, MC1_MASK);

        isp1301_set_bits(isp, ISP1301_MODE_CONTROL_2, MC2_BI_DI);
        isp1301_clear_bits(isp, ISP1301_MODE_CONTROL_2, ~MC2_BI_DI);

        isp1301_set_bits(isp, ISP1301_OTG_CONTROL_1,
                                OTG1_DM_PULLDOWN | OTG1_DP_PULLDOWN);
        isp1301_clear_bits(isp, ISP1301_OTG_CONTROL_1,
                                ~(OTG1_DM_PULLDOWN | OTG1_DP_PULLDOWN));

        isp1301_clear_bits(isp, ISP1301_INTERRUPT_LATCH, ~0);
        isp1301_clear_bits(isp, ISP1301_INTERRUPT_FALLING, ~0);
        isp1301_clear_bits(isp, ISP1301_INTERRUPT_RISING, ~0);

#ifdef  CONFIG_USB_OTG
        status = otg_bind(isp);
        if (status < 0) {
                dev_dbg(&i2c->dev, "can't bind OTG\n");
                goto fail;
        }
#endif

        if (machine_is_omap_h2()) {
                /* full speed signaling by default */
                isp1301_set_bits(isp, ISP1301_MODE_CONTROL_1,
                        MC1_SPEED);
                isp1301_set_bits(isp, ISP1301_MODE_CONTROL_2,
                        MC2_SPD_SUSP_CTRL);

                /* IRQ wired at M14 */
                omap_cfg_reg(M14_1510_GPIO2);
                if (gpio_request(2, "isp1301") == 0)
                        gpio_direction_input(2);
                isp->irq_type = IRQF_TRIGGER_FALLING;
        }

        status = request_irq(i2c->irq, isp1301_irq,
                        isp->irq_type, DRIVER_NAME, isp);
        if (status < 0) {
                dev_dbg(&i2c->dev, "can't get IRQ %d, err %d\n",
                                i2c->irq, status);
                goto fail;
        }

        isp->phy.dev = &i2c->dev;
        isp->phy.label = DRIVER_NAME;
        isp->phy.set_power = isp1301_set_power,

        isp->phy.otg->phy = &isp->phy;
        isp->phy.otg->set_host = isp1301_set_host,
        isp->phy.otg->set_peripheral = isp1301_set_peripheral,
        isp->phy.otg->start_srp = isp1301_start_srp,
        isp->phy.otg->start_hnp = isp1301_start_hnp,

        enable_vbus_draw(isp, 0);
        power_down(isp);
        the_transceiver = isp;

#ifdef  CONFIG_USB_OTG
        update_otg1(isp, isp1301_get_u8(isp, ISP1301_INTERRUPT_SOURCE));
        update_otg2(isp, isp1301_get_u8(isp, ISP1301_OTG_STATUS));
#endif

        dump_regs(isp, __func__);

#ifdef  VERBOSE
        mod_timer(&isp->timer, jiffies + TIMER_JIFFIES);
        dev_dbg(&i2c->dev, "scheduled timer, %d min\n", TIMER_MINUTES);
#endif

        status = usb_add_phy(&isp->phy, USB_PHY_TYPE_USB2);
        if (status < 0)
                dev_err(&i2c->dev, "can't register transceiver, %d\n",
                        status);

        return 0;

fail:
        kfree(isp->phy.otg);
        kfree(isp);
        return -ENODEV;
}

static const struct i2c_device_id isp1301_id[] = {
        { "isp1301_omap", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, isp1301_id);

static struct i2c_driver isp1301_driver = {
        .driver = {
                .name   = "isp1301_omap",
        },
        .probe          = isp1301_probe,
        .remove         = isp1301_remove,
        .id_table       = isp1301_id,
};

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

static int __init isp_init(void)
{
        return i2c_add_driver(&isp1301_driver);
}
subsys_initcall(isp_init);

static void __exit isp_exit(void)
{
        if (the_transceiver)
                usb_remove_phy(&the_transceiver->phy);
        i2c_del_driver(&isp1301_driver);
}
module_exit(isp_exit);