/*
 * otg.c - ChipIdea USB IP core OTG driver
 *
 * Copyright (C) 2013 Freescale Semiconductor, Inc.
 *
 * Author: Peter Chen
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

/*
 * This file mainly handles otgsc register, OTG fsm operations for HNP and SRP
 * are also included.
 */

#include <linux/usb/otg.h>
#include <linux/usb/gadget.h>
#include <linux/usb/chipidea.h>

#include "ci.h"
#include "bits.h"
#include "otg.h"
#include "otg_fsm.h"

/**
 * hw_read_otgsc returns otgsc register bits value.
 * @mask: bitfield mask
 */
u32 hw_read_otgsc(struct ci_hdrc *ci, u32 mask)
{
        struct ci_hdrc_cable *cable;
        u32 val = hw_read(ci, OP_OTGSC, mask);

        /*
         * If using extcon framework for VBUS and/or ID signal
         * detection overwrite OTGSC register value
         */
        cable = &ci->platdata->vbus_extcon;
        if (!IS_ERR(cable->edev)) {
                if (cable->changed)
                        val |= OTGSC_BSVIS;
                else
                        val &= ~OTGSC_BSVIS;

                if (cable->connected)
                        val |= OTGSC_BSV;
                else
                        val &= ~OTGSC_BSV;

                if (cable->enabled)
                        val |= OTGSC_BSVIE;
                else
                        val &= ~OTGSC_BSVIE;
        }

        cable = &ci->platdata->id_extcon;
        if (!IS_ERR(cable->edev)) {
                if (cable->changed)
                        val |= OTGSC_IDIS;
                else
                        val &= ~OTGSC_IDIS;

                if (cable->connected)
                        val &= ~OTGSC_ID; /* host */
                else
                        val |= OTGSC_ID; /* device */

                if (cable->enabled)
                        val |= OTGSC_IDIE;
                else
                        val &= ~OTGSC_IDIE;
        }

        return val & mask;
}

/**
 * hw_write_otgsc updates target bits of OTGSC register.
 * @mask: bitfield mask
 * @data: to be written
 */
void hw_write_otgsc(struct ci_hdrc *ci, u32 mask, u32 data)
{
        struct ci_hdrc_cable *cable;

        cable = &ci->platdata->vbus_extcon;
        if (!IS_ERR(cable->edev)) {
                if (data & mask & OTGSC_BSVIS)
                        cable->changed = false;

                /* Don't enable vbus interrupt if using external notifier */
                if (data & mask & OTGSC_BSVIE) {
                        cable->enabled = true;
                        data &= ~OTGSC_BSVIE;
                } else if (mask & OTGSC_BSVIE) {
                        cable->enabled = false;
                }
        }

        cable = &ci->platdata->id_extcon;
        if (!IS_ERR(cable->edev)) {
                if (data & mask & OTGSC_IDIS)
                        cable->changed = false;

                /* Don't enable id interrupt if using external notifier */
                if (data & mask & OTGSC_IDIE) {
                        cable->enabled = true;
                        data &= ~OTGSC_IDIE;
                } else if (mask & OTGSC_IDIE) {
                        cable->enabled = false;
                }
        }

        hw_write(ci, OP_OTGSC, mask | OTGSC_INT_STATUS_BITS, data);
}

/**
 * ci_otg_role - pick role based on ID pin state
 * @ci: the controller
 */
enum ci_role ci_otg_role(struct ci_hdrc *ci)
{
        enum ci_role role = hw_read_otgsc(ci, OTGSC_ID)
                ? CI_ROLE_GADGET
                : CI_ROLE_HOST;

        return role;
}

void ci_handle_vbus_change(struct ci_hdrc *ci)
{
        if (!ci->is_otg)
                return;

        if (hw_read_otgsc(ci, OTGSC_BSV) && !ci->vbus_active)
                usb_gadget_vbus_connect(&ci->gadget);
        else if (!hw_read_otgsc(ci, OTGSC_BSV) && ci->vbus_active)
                usb_gadget_vbus_disconnect(&ci->gadget);
}

/**
 * When we switch to device mode, the vbus value should be lower
 * than OTGSC_BSV before connecting to host.
 *
 * @ci: the controller
 *
 * This function returns an error code if timeout
 */
static int hw_wait_vbus_lower_bsv(struct ci_hdrc *ci)
{
        unsigned long elapse = jiffies + msecs_to_jiffies(5000);
        u32 mask = OTGSC_BSV;

        while (hw_read_otgsc(ci, mask)) {
                if (time_after(jiffies, elapse)) {
                        dev_err(ci->dev, "timeout waiting for %08x in OTGSC\n",
                                        mask);
                        return -ETIMEDOUT;
                }
                msleep(20);
        }

        return 0;
}

static void ci_handle_id_switch(struct ci_hdrc *ci)
{
        enum ci_role role = ci_otg_role(ci);

        if (role != ci->role) {
                dev_dbg(ci->dev, "switching from %s to %s\n",
                        ci_role(ci)->name, ci->roles[role]->name);

                ci_role_stop(ci);

                if (role == CI_ROLE_GADGET &&
                                IS_ERR(ci->platdata->vbus_extcon.edev))
                        /*
                         * Wait vbus lower than OTGSC_BSV before connecting
                         * to host. If connecting status is from an external
                         * connector instead of register, we don't need to
                         * care vbus on the board, since it will not affect
                         * external connector status.
                         */
                        hw_wait_vbus_lower_bsv(ci);

                ci_role_start(ci, role);
                /* vbus change may have already occurred */
                if (role == CI_ROLE_GADGET)
                        ci_handle_vbus_change(ci);
        }
}
/**
 * ci_otg_work - perform otg (vbus/id) event handle
 * @work: work struct
 */
static void ci_otg_work(struct work_struct *work)
{
        struct ci_hdrc *ci = container_of(work, struct ci_hdrc, work);

        if (ci_otg_is_fsm_mode(ci) && !ci_otg_fsm_work(ci)) {
                enable_irq(ci->irq);
                return;
        }

        pm_runtime_get_sync(ci->dev);
        if (ci->id_event) {
                ci->id_event = false;
                ci_handle_id_switch(ci);
        } else if (ci->b_sess_valid_event) {
                ci->b_sess_valid_event = false;
                ci_handle_vbus_change(ci);
        } else
                dev_err(ci->dev, "unexpected event occurs at %s\n", __func__);
        pm_runtime_put_sync(ci->dev);

        enable_irq(ci->irq);
}


/**
 * ci_hdrc_otg_init - initialize otg struct
 * ci: the controller
 */
int ci_hdrc_otg_init(struct ci_hdrc *ci)
{
        INIT_WORK(&ci->work, ci_otg_work);
        ci->wq = create_freezable_workqueue("ci_otg");
        if (!ci->wq) {
                dev_err(ci->dev, "can't create workqueue\n");
                return -ENODEV;
        }

        if (ci_otg_is_fsm_mode(ci))
                return ci_hdrc_otg_fsm_init(ci);

        return 0;
}

/**
 * ci_hdrc_otg_destroy - destroy otg struct
 * ci: the controller
 */
void ci_hdrc_otg_destroy(struct ci_hdrc *ci)
{
        if (ci->wq) {
                flush_workqueue(ci->wq);
                destroy_workqueue(ci->wq);
        }
        /* Disable all OTG irq and clear status */
        hw_write_otgsc(ci, OTGSC_INT_EN_BITS | OTGSC_INT_STATUS_BITS,
                                                OTGSC_INT_STATUS_BITS);
        if (ci_otg_is_fsm_mode(ci))
                ci_hdrc_otg_fsm_remove(ci);
}