xref: /linux/drivers/usb/chipidea/otg_fsm.c (revision f5e9d31e79c1ce8ba948ecac74d75e9c8d2f0c87)

// SPDX-License-Identifier: GPL-2.0
/*
 * otg_fsm.c - ChipIdea USB IP core OTG FSM driver
 *
 * Copyright (C) 2014 Freescale Semiconductor, Inc.
 *
 * Author: Jun Li
 */

/*
 * This file mainly handles OTG fsm, it includes OTG fsm operations
 * for HNP and SRP.
 *
 * TODO List
 * - ADP
 * - OTG test device
 */

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

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

/* Add for otg: interact with user space app */
static ssize_t
a_bus_req_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	char		*next;
	unsigned	size, t;
	struct ci_hdrc	*ci = dev_get_drvdata(dev);

	next = buf;
	size = PAGE_SIZE;
	t = scnprintf(next, size, "%d\n", ci->fsm.a_bus_req);
	size -= t;
	next += t;

	return PAGE_SIZE - size;
}

static ssize_t
a_bus_req_store(struct device *dev, struct device_attribute *attr,
					const char *buf, size_t count)
{
	struct ci_hdrc *ci = dev_get_drvdata(dev);

	if (count > 2)
		return -1;

	mutex_lock(&ci->fsm.lock);
	if (buf[0] == '0') {
		ci->fsm.a_bus_req = 0;
	} else if (buf[0] == '1') {
		/* If a_bus_drop is TRUE, a_bus_req can't be set */
		if (ci->fsm.a_bus_drop) {
			mutex_unlock(&ci->fsm.lock);
			return count;
		}
		ci->fsm.a_bus_req = 1;
		if (ci->fsm.otg->state == OTG_STATE_A_PERIPHERAL) {
			ci->gadget.host_request_flag = 1;
			mutex_unlock(&ci->fsm.lock);
			return count;
		}
	}

	ci_otg_queue_work(ci);
	mutex_unlock(&ci->fsm.lock);

	return count;
}
static DEVICE_ATTR_RW(a_bus_req);

static ssize_t
a_bus_drop_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	char		*next;
	unsigned	size, t;
	struct ci_hdrc	*ci = dev_get_drvdata(dev);

	next = buf;
	size = PAGE_SIZE;
	t = scnprintf(next, size, "%d\n", ci->fsm.a_bus_drop);
	size -= t;
	next += t;

	return PAGE_SIZE - size;
}

static ssize_t
a_bus_drop_store(struct device *dev, struct device_attribute *attr,
					const char *buf, size_t count)
{
	struct ci_hdrc	*ci = dev_get_drvdata(dev);

	if (count > 2)
		return -1;

	mutex_lock(&ci->fsm.lock);
	if (buf[0] == '0') {
		ci->fsm.a_bus_drop = 0;
	} else if (buf[0] == '1') {
		ci->fsm.a_bus_drop = 1;
		ci->fsm.a_bus_req = 0;
	}

	ci_otg_queue_work(ci);
	mutex_unlock(&ci->fsm.lock);

	return count;
}
static DEVICE_ATTR_RW(a_bus_drop);

static ssize_t
b_bus_req_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	char		*next;
	unsigned	size, t;
	struct ci_hdrc	*ci = dev_get_drvdata(dev);

	next = buf;
	size = PAGE_SIZE;
	t = scnprintf(next, size, "%d\n", ci->fsm.b_bus_req);
	size -= t;
	next += t;

	return PAGE_SIZE - size;
}

static ssize_t
b_bus_req_store(struct device *dev, struct device_attribute *attr,
					const char *buf, size_t count)
{
	struct ci_hdrc	*ci = dev_get_drvdata(dev);

	if (count > 2)
		return -1;

	mutex_lock(&ci->fsm.lock);
	if (buf[0] == '0')
		ci->fsm.b_bus_req = 0;
	else if (buf[0] == '1') {
		ci->fsm.b_bus_req = 1;
		if (ci->fsm.otg->state == OTG_STATE_B_PERIPHERAL) {
			ci->gadget.host_request_flag = 1;
			mutex_unlock(&ci->fsm.lock);
			return count;
		}
	}

	ci_otg_queue_work(ci);
	mutex_unlock(&ci->fsm.lock);

	return count;
}
static DEVICE_ATTR_RW(b_bus_req);

static ssize_t
a_clr_err_store(struct device *dev, struct device_attribute *attr,
					const char *buf, size_t count)
{
	struct ci_hdrc	*ci = dev_get_drvdata(dev);

	if (count > 2)
		return -1;

	mutex_lock(&ci->fsm.lock);
	if (buf[0] == '1')
		ci->fsm.a_clr_err = 1;

	ci_otg_queue_work(ci);
	mutex_unlock(&ci->fsm.lock);

	return count;
}
static DEVICE_ATTR_WO(a_clr_err);

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

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

/*
 * Keep this list in the same order as timers indexed
 * by enum otg_fsm_timer in include/linux/usb/otg-fsm.h
 */
static unsigned otg_timer_ms[] = {
	TA_WAIT_VRISE,
	TA_WAIT_VFALL,
	TA_WAIT_BCON,
	TA_AIDL_BDIS,
	TB_ASE0_BRST,
	TA_BIDL_ADIS,
	TB_AIDL_BDIS,
	TB_SE0_SRP,
	TB_SRP_FAIL,
	0,
	TB_DATA_PLS,
	TB_SSEND_SRP,
};

/*
 * Add timer to active timer list
 */
static void ci_otg_add_timer(struct ci_hdrc *ci, enum otg_fsm_timer t)
{
	unsigned long flags, timer_sec, timer_nsec;

	if (t >= NUM_OTG_FSM_TIMERS)
		return;

	spin_lock_irqsave(&ci->lock, flags);
	timer_sec = otg_timer_ms[t] / MSEC_PER_SEC;
	timer_nsec = (otg_timer_ms[t] % MSEC_PER_SEC) * NSEC_PER_MSEC;
	ci->hr_timeouts[t] = ktime_add(ktime_get(),
				ktime_set(timer_sec, timer_nsec));
	ci->enabled_otg_timer_bits |= (1 << t);
	if ((ci->next_otg_timer == NUM_OTG_FSM_TIMERS) ||
			ktime_after(ci->hr_timeouts[ci->next_otg_timer],
						ci->hr_timeouts[t])) {
			ci->next_otg_timer = t;
			hrtimer_start_range_ns(&ci->otg_fsm_hrtimer,
					ci->hr_timeouts[t], NSEC_PER_MSEC,
							HRTIMER_MODE_ABS);
	}
	spin_unlock_irqrestore(&ci->lock, flags);
}

/*
 * Remove timer from active timer list
 */
static void ci_otg_del_timer(struct ci_hdrc *ci, enum otg_fsm_timer t)
{
	unsigned long flags, enabled_timer_bits;
	enum otg_fsm_timer cur_timer, next_timer = NUM_OTG_FSM_TIMERS;

	if ((t >= NUM_OTG_FSM_TIMERS) ||
			!(ci->enabled_otg_timer_bits & (1 << t)))
		return;

	spin_lock_irqsave(&ci->lock, flags);
	ci->enabled_otg_timer_bits &= ~(1 << t);
	if (ci->next_otg_timer == t) {
		if (ci->enabled_otg_timer_bits == 0) {
			spin_unlock_irqrestore(&ci->lock, flags);
			/* No enabled timers after delete it */
			hrtimer_cancel(&ci->otg_fsm_hrtimer);
			spin_lock_irqsave(&ci->lock, flags);
			ci->next_otg_timer = NUM_OTG_FSM_TIMERS;
		} else {
			/* Find the next timer */
			enabled_timer_bits = ci->enabled_otg_timer_bits;
			for_each_set_bit(cur_timer, &enabled_timer_bits,
							NUM_OTG_FSM_TIMERS) {
				if ((next_timer == NUM_OTG_FSM_TIMERS) ||
					ktime_before(ci->hr_timeouts[next_timer],
					 ci->hr_timeouts[cur_timer]))
					next_timer = cur_timer;
			}
		}
	}
	if (next_timer != NUM_OTG_FSM_TIMERS) {
		ci->next_otg_timer = next_timer;
		hrtimer_start_range_ns(&ci->otg_fsm_hrtimer,
			ci->hr_timeouts[next_timer], NSEC_PER_MSEC,
							HRTIMER_MODE_ABS);
	}
	spin_unlock_irqrestore(&ci->lock, flags);
}

/* OTG FSM timer handlers */
static int a_wait_vrise_tmout(struct ci_hdrc *ci)
{
	ci->fsm.a_wait_vrise_tmout = 1;
	return 0;
}

static int a_wait_vfall_tmout(struct ci_hdrc *ci)
{
	ci->fsm.a_wait_vfall_tmout = 1;
	return 0;
}

static int a_wait_bcon_tmout(struct ci_hdrc *ci)
{
	ci->fsm.a_wait_bcon_tmout = 1;
	return 0;
}

static int a_aidl_bdis_tmout(struct ci_hdrc *ci)
{
	ci->fsm.a_aidl_bdis_tmout = 1;
	return 0;
}

static int b_ase0_brst_tmout(struct ci_hdrc *ci)
{
	ci->fsm.b_ase0_brst_tmout = 1;
	return 0;
}

static int a_bidl_adis_tmout(struct ci_hdrc *ci)
{
	ci->fsm.a_bidl_adis_tmout = 1;
	return 0;
}

static int b_aidl_bdis_tmout(struct ci_hdrc *ci)
{
	ci->fsm.a_bus_suspend = 1;
	return 0;
}

static int b_se0_srp_tmout(struct ci_hdrc *ci)
{
	ci->fsm.b_se0_srp = 1;
	return 0;
}

static int b_srp_fail_tmout(struct ci_hdrc *ci)
{
	ci->fsm.b_srp_done = 1;
	return 1;
}

static int b_data_pls_tmout(struct ci_hdrc *ci)
{
	ci->fsm.b_srp_done = 1;
	ci->fsm.b_bus_req = 0;
	if (ci->fsm.power_up)
		ci->fsm.power_up = 0;
	hw_write_otgsc(ci, OTGSC_HABA, 0);
	pm_runtime_put(ci->dev);
	return 0;
}

static int b_ssend_srp_tmout(struct ci_hdrc *ci)
{
	ci->fsm.b_ssend_srp = 1;
	/* only vbus fall below B_sess_vld in b_idle state */
	if (ci->fsm.otg->state == OTG_STATE_B_IDLE)
		return 0;
	else
		return 1;
}

/*
 * Keep this list in the same order as timers indexed
 * by enum otg_fsm_timer in include/linux/usb/otg-fsm.h
 */
static int (*otg_timer_handlers[])(struct ci_hdrc *) = {
	a_wait_vrise_tmout,	/* A_WAIT_VRISE */
	a_wait_vfall_tmout,	/* A_WAIT_VFALL */
	a_wait_bcon_tmout,	/* A_WAIT_BCON */
	a_aidl_bdis_tmout,	/* A_AIDL_BDIS */
	b_ase0_brst_tmout,	/* B_ASE0_BRST */
	a_bidl_adis_tmout,	/* A_BIDL_ADIS */
	b_aidl_bdis_tmout,	/* B_AIDL_BDIS */
	b_se0_srp_tmout,	/* B_SE0_SRP */
	b_srp_fail_tmout,	/* B_SRP_FAIL */
	NULL,			/* A_WAIT_ENUM */
	b_data_pls_tmout,	/* B_DATA_PLS */
	b_ssend_srp_tmout,	/* B_SSEND_SRP */
};

/*
 * Enable the next nearest enabled timer if have
 */
static enum hrtimer_restart ci_otg_hrtimer_func(struct hrtimer *t)
{
	struct ci_hdrc *ci = container_of(t, struct ci_hdrc, otg_fsm_hrtimer);
	ktime_t	now, *timeout;
	unsigned long   enabled_timer_bits;
	unsigned long   flags;
	enum otg_fsm_timer cur_timer, next_timer = NUM_OTG_FSM_TIMERS;
	int ret = -EINVAL;

	spin_lock_irqsave(&ci->lock, flags);
	enabled_timer_bits = ci->enabled_otg_timer_bits;
	ci->next_otg_timer = NUM_OTG_FSM_TIMERS;

	now = ktime_get();
	for_each_set_bit(cur_timer, &enabled_timer_bits, NUM_OTG_FSM_TIMERS) {
		if (ktime_compare(now, ci->hr_timeouts[cur_timer]) >= 0) {
			ci->enabled_otg_timer_bits &= ~(1 << cur_timer);
			if (otg_timer_handlers[cur_timer])
				ret = otg_timer_handlers[cur_timer](ci);
		} else {
			if ((next_timer == NUM_OTG_FSM_TIMERS) ||
				ktime_before(ci->hr_timeouts[cur_timer],
					ci->hr_timeouts[next_timer]))
				next_timer = cur_timer;
		}
	}
	/* Enable the next nearest timer */
	if (next_timer < NUM_OTG_FSM_TIMERS) {
		timeout = &ci->hr_timeouts[next_timer];
		hrtimer_start_range_ns(&ci->otg_fsm_hrtimer, *timeout,
					NSEC_PER_MSEC, HRTIMER_MODE_ABS);
		ci->next_otg_timer = next_timer;
	}
	spin_unlock_irqrestore(&ci->lock, flags);

	if (!ret)
		ci_otg_queue_work(ci);

	return HRTIMER_NORESTART;
}

/* Initialize timers */
static int ci_otg_init_timers(struct ci_hdrc *ci)
{
	hrtimer_setup(&ci->otg_fsm_hrtimer, ci_otg_hrtimer_func, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);

	return 0;
}

/* -------------------------------------------------------------*/
/* Operations that will be called from OTG Finite State Machine */
/* -------------------------------------------------------------*/
static void ci_otg_fsm_add_timer(struct otg_fsm *fsm, enum otg_fsm_timer t)
{
	struct ci_hdrc	*ci = container_of(fsm, struct ci_hdrc, fsm);

	if (t < NUM_OTG_FSM_TIMERS)
		ci_otg_add_timer(ci, t);
	return;
}

static void ci_otg_fsm_del_timer(struct otg_fsm *fsm, enum otg_fsm_timer t)
{
	struct ci_hdrc	*ci = container_of(fsm, struct ci_hdrc, fsm);

	if (t < NUM_OTG_FSM_TIMERS)
		ci_otg_del_timer(ci, t);
	return;
}

/*
 * A-device drive vbus: turn on vbus regulator and enable port power
 * Data pulse irq should be disabled while vbus is on.
 */
static void ci_otg_drv_vbus(struct otg_fsm *fsm, int on)
{
	int ret;
	struct ci_hdrc	*ci = container_of(fsm, struct ci_hdrc, fsm);

	if (on) {
		/* Enable power */
		hw_write(ci, OP_PORTSC, PORTSC_W1C_BITS | PORTSC_PP,
							PORTSC_PP);
		if (ci->platdata->reg_vbus) {
			ret = regulator_enable(ci->platdata->reg_vbus);
			if (ret) {
				dev_err(ci->dev,
				"Failed to enable vbus regulator, ret=%d\n",
				ret);
				return;
			}
		}

		if (ci->platdata->flags & CI_HDRC_PHY_VBUS_CONTROL)
			usb_phy_vbus_on(ci->usb_phy);

		/* Disable data pulse irq */
		hw_write_otgsc(ci, OTGSC_DPIE, 0);

		fsm->a_srp_det = 0;
		fsm->power_up = 0;
	} else {
		if (ci->platdata->reg_vbus)
			regulator_disable(ci->platdata->reg_vbus);

		if (ci->platdata->flags & CI_HDRC_PHY_VBUS_CONTROL)
			usb_phy_vbus_off(ci->usb_phy);

		fsm->a_bus_drop = 1;
		fsm->a_bus_req = 0;
	}
}

/*
 * Control data line by Run Stop bit.
 */
static void ci_otg_loc_conn(struct otg_fsm *fsm, int on)
{
	struct ci_hdrc	*ci = container_of(fsm, struct ci_hdrc, fsm);

	if (on)
		hw_write(ci, OP_USBCMD, USBCMD_RS, USBCMD_RS);
	else
		hw_write(ci, OP_USBCMD, USBCMD_RS, 0);
}

/*
 * Generate SOF by host.
 * In host mode, controller will automatically send SOF.
 * Suspend will block the data on the port.
 *
 * This is controlled through usbcore by usb autosuspend,
 * so the usb device class driver need support autosuspend,
 * otherwise the bus suspend will not happen.
 */
static void ci_otg_loc_sof(struct otg_fsm *fsm, int on)
{
	struct usb_device *udev;

	if (!fsm->otg->host)
		return;

	udev = usb_hub_find_child(fsm->otg->host->root_hub, 1);
	if (!udev)
		return;

	if (on) {
		usb_disable_autosuspend(udev);
	} else {
		pm_runtime_set_autosuspend_delay(&udev->dev, 0);
		usb_enable_autosuspend(udev);
	}
}

/*
 * Start SRP pulsing by data-line pulsing,
 * no v-bus pulsing followed
 */
static void ci_otg_start_pulse(struct otg_fsm *fsm)
{
	struct ci_hdrc	*ci = container_of(fsm, struct ci_hdrc, fsm);

	/* Hardware Assistant Data pulse */
	hw_write_otgsc(ci, OTGSC_HADP, OTGSC_HADP);

	pm_runtime_get(ci->dev);
	ci_otg_add_timer(ci, B_DATA_PLS);
}

static int ci_otg_start_host(struct otg_fsm *fsm, int on)
{
	struct ci_hdrc	*ci = container_of(fsm, struct ci_hdrc, fsm);

	if (on) {
		ci_role_stop(ci);
		ci_role_start(ci, CI_ROLE_HOST);
	} else {
		ci_role_stop(ci);
		ci_role_start(ci, CI_ROLE_GADGET);
	}
	return 0;
}

static int ci_otg_start_gadget(struct otg_fsm *fsm, int on)
{
	struct ci_hdrc	*ci = container_of(fsm, struct ci_hdrc, fsm);

	if (on)
		usb_gadget_vbus_connect(&ci->gadget);
	else
		usb_gadget_vbus_disconnect(&ci->gadget);

	return 0;
}

static struct otg_fsm_ops ci_otg_ops = {
	.drv_vbus = ci_otg_drv_vbus,
	.loc_conn = ci_otg_loc_conn,
	.loc_sof = ci_otg_loc_sof,
	.start_pulse = ci_otg_start_pulse,
	.add_timer = ci_otg_fsm_add_timer,
	.del_timer = ci_otg_fsm_del_timer,
	.start_host = ci_otg_start_host,
	.start_gadget = ci_otg_start_gadget,
};

int ci_otg_fsm_work(struct ci_hdrc *ci)
{
	/*
	 * Don't do fsm transition for B device
	 * when there is no gadget class driver
	 */
	if (ci->fsm.id && !(ci->driver) &&
		ci->fsm.otg->state < OTG_STATE_A_IDLE)
		return 0;

	pm_runtime_get_sync(ci->dev);
	if (otg_statemachine(&ci->fsm)) {
		if (ci->fsm.otg->state == OTG_STATE_A_IDLE) {
			/*
			 * Further state change for cases:
			 * a_idle to b_idle; or
			 * a_idle to a_wait_vrise due to ID change(1->0), so
			 * B-dev becomes A-dev can try to start new session
			 * consequently; or
			 * a_idle to a_wait_vrise when power up
			 */
			if ((ci->fsm.id) || (ci->id_event) ||
						(ci->fsm.power_up)) {
				ci_otg_queue_work(ci);
			} else {
				/* Enable data pulse irq */
				hw_write(ci, OP_PORTSC, PORTSC_W1C_BITS |
								PORTSC_PP, 0);
				hw_write_otgsc(ci, OTGSC_DPIS, OTGSC_DPIS);
				hw_write_otgsc(ci, OTGSC_DPIE, OTGSC_DPIE);
			}
			if (ci->id_event)
				ci->id_event = false;
		} else if (ci->fsm.otg->state == OTG_STATE_B_IDLE) {
			if (ci->fsm.b_sess_vld) {
				ci->fsm.power_up = 0;
				/*
				 * Further transite to b_periphearl state
				 * when register gadget driver with vbus on
				 */
				ci_otg_queue_work(ci);
			}
		} else if (ci->fsm.otg->state == OTG_STATE_A_HOST) {
			pm_runtime_put_autosuspend(ci->dev);
			return 0;
		}
	}
	pm_runtime_put_sync(ci->dev);
	return 0;
}

/*
 * Update fsm variables in each state if catching expected interrupts,
 * called by otg fsm isr.
 */
static void ci_otg_fsm_event(struct ci_hdrc *ci)
{
	u32 intr_sts, otg_bsess_vld, port_conn;
	struct otg_fsm *fsm = &ci->fsm;

	intr_sts = hw_read_intr_status(ci);
	otg_bsess_vld = hw_read_otgsc(ci, OTGSC_BSV);
	port_conn = hw_read(ci, OP_PORTSC, PORTSC_CCS);

	switch (ci->fsm.otg->state) {
	case OTG_STATE_A_WAIT_BCON:
		if (port_conn) {
			fsm->b_conn = 1;
			fsm->a_bus_req = 1;
			ci_otg_queue_work(ci);
		}
		break;
	case OTG_STATE_B_IDLE:
		if (otg_bsess_vld && (intr_sts & USBi_PCI) && port_conn) {
			fsm->b_sess_vld = 1;
			ci_otg_queue_work(ci);
		}
		break;
	case OTG_STATE_B_PERIPHERAL:
		if ((intr_sts & USBi_SLI) && port_conn && otg_bsess_vld) {
			ci_otg_add_timer(ci, B_AIDL_BDIS);
		} else if (intr_sts & USBi_PCI) {
			ci_otg_del_timer(ci, B_AIDL_BDIS);
			if (fsm->a_bus_suspend == 1)
				fsm->a_bus_suspend = 0;
		}
		break;
	case OTG_STATE_B_HOST:
		if ((intr_sts & USBi_PCI) && !port_conn) {
			fsm->a_conn = 0;
			fsm->b_bus_req = 0;
			ci_otg_queue_work(ci);
		}
		break;
	case OTG_STATE_A_PERIPHERAL:
		if (intr_sts & USBi_SLI) {
			 fsm->b_bus_suspend = 1;
			/*
			 * Init a timer to know how long this suspend
			 * will continue, if time out, indicates B no longer
			 * wants to be host role
			 */
			 ci_otg_add_timer(ci, A_BIDL_ADIS);
		}

		if (intr_sts & USBi_URI)
			ci_otg_del_timer(ci, A_BIDL_ADIS);

		if (intr_sts & USBi_PCI) {
			if (fsm->b_bus_suspend == 1) {
				ci_otg_del_timer(ci, A_BIDL_ADIS);
				fsm->b_bus_suspend = 0;
			}
		}
		break;
	case OTG_STATE_A_SUSPEND:
		if ((intr_sts & USBi_PCI) && !port_conn) {
			fsm->b_conn = 0;

			/* if gadget driver is binded */
			if (ci->driver) {
				/* A device to be peripheral mode */
				ci->gadget.is_a_peripheral = 1;
			}
			ci_otg_queue_work(ci);
		}
		break;
	case OTG_STATE_A_HOST:
		if ((intr_sts & USBi_PCI) && !port_conn) {
			fsm->b_conn = 0;
			ci_otg_queue_work(ci);
		}
		break;
	case OTG_STATE_B_WAIT_ACON:
		if ((intr_sts & USBi_PCI) && port_conn) {
			fsm->a_conn = 1;
			ci_otg_queue_work(ci);
		}
		break;
	default:
		break;
	}
}

/*
 * ci_otg_irq - otg fsm related irq handling
 * and also update otg fsm variable by monitoring usb host and udc
 * state change interrupts.
 * @ci: ci_hdrc
 */
irqreturn_t ci_otg_fsm_irq(struct ci_hdrc *ci)
{
	irqreturn_t retval =  IRQ_NONE;
	u32 otgsc, otg_int_src = 0;
	struct otg_fsm *fsm = &ci->fsm;

	otgsc = hw_read_otgsc(ci, ~0);
	otg_int_src = otgsc & OTGSC_INT_STATUS_BITS & (otgsc >> 8);
	fsm->id = (otgsc & OTGSC_ID) ? 1 : 0;

	if (otg_int_src) {
		if (otg_int_src & OTGSC_DPIS) {
			hw_write_otgsc(ci, OTGSC_DPIS, OTGSC_DPIS);
			fsm->a_srp_det = 1;
			fsm->a_bus_drop = 0;
		} else if (otg_int_src & OTGSC_IDIS) {
			hw_write_otgsc(ci, OTGSC_IDIS, OTGSC_IDIS);
			if (fsm->id == 0) {
				fsm->a_bus_drop = 0;
				fsm->a_bus_req = 1;
				ci->id_event = true;
			}
		} else if (otg_int_src & OTGSC_BSVIS) {
			hw_write_otgsc(ci, OTGSC_BSVIS, OTGSC_BSVIS);
			if (otgsc & OTGSC_BSV) {
				fsm->b_sess_vld = 1;
				ci_otg_del_timer(ci, B_SSEND_SRP);
				ci_otg_del_timer(ci, B_SRP_FAIL);
				fsm->b_ssend_srp = 0;
			} else {
				fsm->b_sess_vld = 0;
				if (fsm->id)
					ci_otg_add_timer(ci, B_SSEND_SRP);
			}
		} else if (otg_int_src & OTGSC_AVVIS) {
			hw_write_otgsc(ci, OTGSC_AVVIS, OTGSC_AVVIS);
			if (otgsc & OTGSC_AVV) {
				fsm->a_vbus_vld = 1;
			} else {
				fsm->a_vbus_vld = 0;
				fsm->b_conn = 0;
			}
		}
		ci_otg_queue_work(ci);
		return IRQ_HANDLED;
	}

	ci_otg_fsm_event(ci);

	return retval;
}

void ci_hdrc_otg_fsm_start(struct ci_hdrc *ci)
{
	ci_otg_queue_work(ci);
}

int ci_hdrc_otg_fsm_init(struct ci_hdrc *ci)
{
	int retval = 0;

	if (ci->phy)
		ci->otg.phy = ci->phy;
	else
		ci->otg.usb_phy = ci->usb_phy;

	ci->otg.gadget = &ci->gadget;
	ci->fsm.otg = &ci->otg;
	ci->fsm.power_up = 1;
	ci->fsm.id = hw_read_otgsc(ci, OTGSC_ID) ? 1 : 0;
	ci->fsm.otg->state = OTG_STATE_UNDEFINED;
	ci->fsm.ops = &ci_otg_ops;
	ci->gadget.hnp_polling_support = 1;
	ci->fsm.host_req_flag = devm_kzalloc(ci->dev, 1, GFP_KERNEL);
	if (!ci->fsm.host_req_flag)
		return -ENOMEM;

	mutex_init(&ci->fsm.lock);

	retval = ci_otg_init_timers(ci);
	if (retval) {
		dev_err(ci->dev, "Couldn't init OTG timers\n");
		return retval;
	}
	ci->enabled_otg_timer_bits = 0;
	ci->next_otg_timer = NUM_OTG_FSM_TIMERS;

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

	/* Enable A vbus valid irq */
	hw_write_otgsc(ci, OTGSC_AVVIE, OTGSC_AVVIE);

	if (ci->fsm.id) {
		ci->fsm.b_ssend_srp =
			hw_read_otgsc(ci, OTGSC_BSV) ? 0 : 1;
		ci->fsm.b_sess_vld =
			hw_read_otgsc(ci, OTGSC_BSV) ? 1 : 0;
		/* Enable BSV irq */
		hw_write_otgsc(ci, OTGSC_BSVIE, OTGSC_BSVIE);
	}

	return 0;
}

void ci_hdrc_otg_fsm_remove(struct ci_hdrc *ci)
{
	sysfs_remove_group(&ci->dev->kobj, &inputs_attr_group);
}