// SPDX-License-Identifier: GPL-2.0+
/*
 * OTG Finite State Machine from OTG spec
 *
 * Copyright (C) 2007,2008 Freescale Semiconductor, Inc.
 *
 * Author:      Li Yang <LeoLi@freescale.com>
 *              Jerry Huang <Chang-Ming.Huang@freescale.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/delay.h>
#include <linux/usb.h>
#include <linux/usb/gadget.h>
#include <linux/usb/otg.h>
#include <linux/usb/otg-fsm.h>

#ifdef VERBOSE
#define VDBG(fmt, args...) pr_debug("[%s]  " fmt, \
                                 __func__, ## args)
#else
#define VDBG(stuff...)  do {} while (0)
#endif

/* Change USB protocol when there is a protocol change */
static int otg_set_protocol(struct otg_fsm *fsm, int protocol)
{
        int ret = 0;

        if (fsm->protocol != protocol) {
                VDBG("Changing role fsm->protocol= %d; new protocol= %d\n",
                        fsm->protocol, protocol);
                /* stop old protocol */
                if (fsm->protocol == PROTO_HOST)
                        ret = otg_start_host(fsm, 0);
                else if (fsm->protocol == PROTO_GADGET)
                        ret = otg_start_gadget(fsm, 0);
                if (ret)
                        return ret;

                /* start new protocol */
                if (protocol == PROTO_HOST)
                        ret = otg_start_host(fsm, 1);
                else if (protocol == PROTO_GADGET)
                        ret = otg_start_gadget(fsm, 1);
                if (ret)
                        return ret;

                fsm->protocol = protocol;
                return 0;
        }

        return 0;
}

/* Called when leaving a state.  Do state clean up jobs here */
static void otg_leave_state(struct otg_fsm *fsm, enum usb_otg_state old_state)
{
        switch (old_state) {
        case OTG_STATE_B_IDLE:
                otg_del_timer(fsm, B_SE0_SRP);
                fsm->b_se0_srp = 0;
                fsm->adp_sns = 0;
                fsm->adp_prb = 0;
                break;
        case OTG_STATE_B_SRP_INIT:
                fsm->data_pulse = 0;
                fsm->b_srp_done = 0;
                break;
        case OTG_STATE_B_PERIPHERAL:
                if (fsm->otg->gadget)
                        fsm->otg->gadget->host_request_flag = 0;
                break;
        case OTG_STATE_B_WAIT_ACON:
                otg_del_timer(fsm, B_ASE0_BRST);
                fsm->b_ase0_brst_tmout = 0;
                break;
        case OTG_STATE_B_HOST:
                break;
        case OTG_STATE_A_IDLE:
                fsm->adp_prb = 0;
                break;
        case OTG_STATE_A_WAIT_VRISE:
                otg_del_timer(fsm, A_WAIT_VRISE);
                fsm->a_wait_vrise_tmout = 0;
                break;
        case OTG_STATE_A_WAIT_BCON:
                otg_del_timer(fsm, A_WAIT_BCON);
                fsm->a_wait_bcon_tmout = 0;
                break;
        case OTG_STATE_A_HOST:
                otg_del_timer(fsm, A_WAIT_ENUM);
                break;
        case OTG_STATE_A_SUSPEND:
                otg_del_timer(fsm, A_AIDL_BDIS);
                fsm->a_aidl_bdis_tmout = 0;
                fsm->a_suspend_req_inf = 0;
                break;
        case OTG_STATE_A_PERIPHERAL:
                otg_del_timer(fsm, A_BIDL_ADIS);
                fsm->a_bidl_adis_tmout = 0;
                if (fsm->otg->gadget)
                        fsm->otg->gadget->host_request_flag = 0;
                break;
        case OTG_STATE_A_WAIT_VFALL:
                otg_del_timer(fsm, A_WAIT_VFALL);
                fsm->a_wait_vfall_tmout = 0;
                otg_del_timer(fsm, A_WAIT_VRISE);
                break;
        case OTG_STATE_A_VBUS_ERR:
                break;
        default:
                break;
        }
}

static void otg_hnp_polling_work(struct work_struct *work)
{
        struct otg_fsm *fsm = container_of(to_delayed_work(work),
                                struct otg_fsm, hnp_polling_work);
        struct usb_device *udev;
        enum usb_otg_state state = fsm->otg->state;
        u8 flag;
        int retval;

        if (state != OTG_STATE_A_HOST && state != OTG_STATE_B_HOST)
                return;

        udev = usb_hub_find_child(fsm->otg->host->root_hub, 1);
        if (!udev) {
                dev_err(fsm->otg->host->controller,
                        "no usb dev connected, can't start HNP polling\n");
                return;
        }

        *fsm->host_req_flag = 0;
        /* Get host request flag from connected USB device */
        retval = usb_control_msg(udev,
                                usb_rcvctrlpipe(udev, 0),
                                USB_REQ_GET_STATUS,
                                USB_DIR_IN | USB_RECIP_DEVICE,
                                0,
                                OTG_STS_SELECTOR,
                                fsm->host_req_flag,
                                1,
                                USB_CTRL_GET_TIMEOUT);
        if (retval != 1) {
                dev_err(&udev->dev, "Get one byte OTG status failed\n");
                return;
        }

        flag = *fsm->host_req_flag;
        if (flag == 0) {
                /* Continue HNP polling */
                schedule_delayed_work(&fsm->hnp_polling_work,
                                        msecs_to_jiffies(T_HOST_REQ_POLL));
                return;
        } else if (flag != HOST_REQUEST_FLAG) {
                dev_err(&udev->dev, "host request flag %d is invalid\n", flag);
                return;
        }

        /* Host request flag is set */
        if (state == OTG_STATE_A_HOST) {
                /* Set b_hnp_enable */
                if (!fsm->otg->host->b_hnp_enable) {
                        retval = usb_control_msg(udev,
                                        usb_sndctrlpipe(udev, 0),
                                        USB_REQ_SET_FEATURE, 0,
                                        USB_DEVICE_B_HNP_ENABLE,
                                        0, NULL, 0,
                                        USB_CTRL_SET_TIMEOUT);
                        if (retval >= 0)
                                fsm->otg->host->b_hnp_enable = 1;
                }
                fsm->a_bus_req = 0;
        } else if (state == OTG_STATE_B_HOST) {
                fsm->b_bus_req = 0;
        }

        otg_statemachine(fsm);
}

static void otg_start_hnp_polling(struct otg_fsm *fsm)
{
        /*
         * The memory of host_req_flag should be allocated by
         * controller driver, otherwise, hnp polling is not started.
         */
        if (!fsm->host_req_flag)
                return;

        if (!fsm->hnp_work_inited) {
                INIT_DELAYED_WORK(&fsm->hnp_polling_work, otg_hnp_polling_work);
                fsm->hnp_work_inited = true;
        }

        schedule_delayed_work(&fsm->hnp_polling_work,
                                        msecs_to_jiffies(T_HOST_REQ_POLL));
}

/* Called when entering a state */
static int otg_set_state(struct otg_fsm *fsm, enum usb_otg_state new_state)
{
        if (fsm->otg->state == new_state)
                return 0;
        VDBG("Set state: %s\n", usb_otg_state_string(new_state));
        otg_leave_state(fsm, fsm->otg->state);
        switch (new_state) {
        case OTG_STATE_B_IDLE:
                otg_drv_vbus(fsm, 0);
                otg_chrg_vbus(fsm, 0);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 0);
                /*
                 * Driver is responsible for starting ADP probing
                 * if ADP sensing times out.
                 */
                otg_start_adp_sns(fsm);
                otg_set_protocol(fsm, PROTO_UNDEF);
                otg_add_timer(fsm, B_SE0_SRP);
                break;
        case OTG_STATE_B_SRP_INIT:
                otg_start_pulse(fsm);
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_UNDEF);
                otg_add_timer(fsm, B_SRP_FAIL);
                break;
        case OTG_STATE_B_PERIPHERAL:
                otg_chrg_vbus(fsm, 0);
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_GADGET);
                otg_loc_conn(fsm, 1);
                break;
        case OTG_STATE_B_WAIT_ACON:
                otg_chrg_vbus(fsm, 0);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_HOST);
                otg_add_timer(fsm, B_ASE0_BRST);
                fsm->a_bus_suspend = 0;
                break;
        case OTG_STATE_B_HOST:
                otg_chrg_vbus(fsm, 0);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 1);
                otg_set_protocol(fsm, PROTO_HOST);
                usb_bus_start_enum(fsm->otg->host,
                                fsm->otg->host->otg_port);
                otg_start_hnp_polling(fsm);
                break;
        case OTG_STATE_A_IDLE:
                otg_drv_vbus(fsm, 0);
                otg_chrg_vbus(fsm, 0);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 0);
                otg_start_adp_prb(fsm);
                otg_set_protocol(fsm, PROTO_HOST);
                break;
        case OTG_STATE_A_WAIT_VRISE:
                otg_drv_vbus(fsm, 1);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_HOST);
                otg_add_timer(fsm, A_WAIT_VRISE);
                break;
        case OTG_STATE_A_WAIT_BCON:
                otg_drv_vbus(fsm, 1);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_HOST);
                otg_add_timer(fsm, A_WAIT_BCON);
                break;
        case OTG_STATE_A_HOST:
                otg_drv_vbus(fsm, 1);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 1);
                otg_set_protocol(fsm, PROTO_HOST);
                /*
                 * When HNP is triggered while a_bus_req = 0, a_host will
                 * suspend too fast to complete a_set_b_hnp_en
                 */
                if (!fsm->a_bus_req || fsm->a_suspend_req_inf)
                        otg_add_timer(fsm, A_WAIT_ENUM);
                otg_start_hnp_polling(fsm);
                break;
        case OTG_STATE_A_SUSPEND:
                otg_drv_vbus(fsm, 1);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_HOST);
                otg_add_timer(fsm, A_AIDL_BDIS);

                break;
        case OTG_STATE_A_PERIPHERAL:
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_GADGET);
                otg_drv_vbus(fsm, 1);
                otg_loc_conn(fsm, 1);
                otg_add_timer(fsm, A_BIDL_ADIS);
                break;
        case OTG_STATE_A_WAIT_VFALL:
                otg_drv_vbus(fsm, 0);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_HOST);
                otg_add_timer(fsm, A_WAIT_VFALL);
                break;
        case OTG_STATE_A_VBUS_ERR:
                otg_drv_vbus(fsm, 0);
                otg_loc_conn(fsm, 0);
                otg_loc_sof(fsm, 0);
                otg_set_protocol(fsm, PROTO_UNDEF);
                break;
        default:
                break;
        }

        fsm->otg->state = new_state;
        fsm->state_changed = 1;
        return 0;
}

/* State change judgement */
int otg_statemachine(struct otg_fsm *fsm)
{
        enum usb_otg_state state;

        mutex_lock(&fsm->lock);

        state = fsm->otg->state;
        fsm->state_changed = 0;
        /* State machine state change judgement */

        switch (state) {
        case OTG_STATE_UNDEFINED:
                VDBG("fsm->id = %d\n", fsm->id);
                if (fsm->id)
                        otg_set_state(fsm, OTG_STATE_B_IDLE);
                else
                        otg_set_state(fsm, OTG_STATE_A_IDLE);
                break;
        case OTG_STATE_B_IDLE:
                if (!fsm->id)
                        otg_set_state(fsm, OTG_STATE_A_IDLE);
                else if (fsm->b_sess_vld && fsm->otg->gadget)
                        otg_set_state(fsm, OTG_STATE_B_PERIPHERAL);
                else if ((fsm->b_bus_req || fsm->adp_change || fsm->power_up) &&
                                fsm->b_ssend_srp && fsm->b_se0_srp)
                        otg_set_state(fsm, OTG_STATE_B_SRP_INIT);
                break;
        case OTG_STATE_B_SRP_INIT:
                if (!fsm->id || fsm->b_srp_done)
                        otg_set_state(fsm, OTG_STATE_B_IDLE);
                break;
        case OTG_STATE_B_PERIPHERAL:
                if (!fsm->id || !fsm->b_sess_vld)
                        otg_set_state(fsm, OTG_STATE_B_IDLE);
                else if (fsm->b_bus_req && fsm->otg->
                                gadget->b_hnp_enable && fsm->a_bus_suspend)
                        otg_set_state(fsm, OTG_STATE_B_WAIT_ACON);
                break;
        case OTG_STATE_B_WAIT_ACON:
                if (fsm->a_conn)
                        otg_set_state(fsm, OTG_STATE_B_HOST);
                else if (!fsm->id || !fsm->b_sess_vld)
                        otg_set_state(fsm, OTG_STATE_B_IDLE);
                else if (fsm->a_bus_resume || fsm->b_ase0_brst_tmout) {
                        fsm->b_ase0_brst_tmout = 0;
                        otg_set_state(fsm, OTG_STATE_B_PERIPHERAL);
                }
                break;
        case OTG_STATE_B_HOST:
                if (!fsm->id || !fsm->b_sess_vld)
                        otg_set_state(fsm, OTG_STATE_B_IDLE);
                else if (!fsm->b_bus_req || !fsm->a_conn || fsm->test_device)
                        otg_set_state(fsm, OTG_STATE_B_PERIPHERAL);
                break;
        case OTG_STATE_A_IDLE:
                if (fsm->id)
                        otg_set_state(fsm, OTG_STATE_B_IDLE);
                else if (!fsm->a_bus_drop && (fsm->a_bus_req ||
                          fsm->a_srp_det || fsm->adp_change || fsm->power_up))
                        otg_set_state(fsm, OTG_STATE_A_WAIT_VRISE);
                break;
        case OTG_STATE_A_WAIT_VRISE:
                if (fsm->a_vbus_vld)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_BCON);
                else if (fsm->id || fsm->a_bus_drop ||
                                fsm->a_wait_vrise_tmout)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
                break;
        case OTG_STATE_A_WAIT_BCON:
                if (!fsm->a_vbus_vld)
                        otg_set_state(fsm, OTG_STATE_A_VBUS_ERR);
                else if (fsm->b_conn)
                        otg_set_state(fsm, OTG_STATE_A_HOST);
                else if (fsm->id || fsm->a_bus_drop || fsm->a_wait_bcon_tmout)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
                break;
        case OTG_STATE_A_HOST:
                if (fsm->id || fsm->a_bus_drop)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
                else if ((!fsm->a_bus_req || fsm->a_suspend_req_inf) &&
                                fsm->otg->host->b_hnp_enable)
                        otg_set_state(fsm, OTG_STATE_A_SUSPEND);
                else if (!fsm->b_conn)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_BCON);
                else if (!fsm->a_vbus_vld)
                        otg_set_state(fsm, OTG_STATE_A_VBUS_ERR);
                break;
        case OTG_STATE_A_SUSPEND:
                if (!fsm->b_conn && fsm->otg->host->b_hnp_enable)
                        otg_set_state(fsm, OTG_STATE_A_PERIPHERAL);
                else if (!fsm->b_conn && !fsm->otg->host->b_hnp_enable)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_BCON);
                else if (fsm->a_bus_req || fsm->b_bus_resume)
                        otg_set_state(fsm, OTG_STATE_A_HOST);
                else if (fsm->id || fsm->a_bus_drop || fsm->a_aidl_bdis_tmout)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
                else if (!fsm->a_vbus_vld)
                        otg_set_state(fsm, OTG_STATE_A_VBUS_ERR);
                break;
        case OTG_STATE_A_PERIPHERAL:
                if (fsm->id || fsm->a_bus_drop)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
                else if (fsm->a_bidl_adis_tmout || fsm->b_bus_suspend)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_BCON);
                else if (!fsm->a_vbus_vld)
                        otg_set_state(fsm, OTG_STATE_A_VBUS_ERR);
                break;
        case OTG_STATE_A_WAIT_VFALL:
                if (fsm->a_wait_vfall_tmout)
                        otg_set_state(fsm, OTG_STATE_A_IDLE);
                break;
        case OTG_STATE_A_VBUS_ERR:
                if (fsm->id || fsm->a_bus_drop || fsm->a_clr_err)
                        otg_set_state(fsm, OTG_STATE_A_WAIT_VFALL);
                break;
        default:
                break;
        }
        mutex_unlock(&fsm->lock);

        VDBG("quit statemachine, changed = %d\n", fsm->state_changed);
        return fsm->state_changed;
}
EXPORT_SYMBOL_GPL(otg_statemachine);
MODULE_DESCRIPTION("OTG Finite State Machine");
MODULE_LICENSE("GPL");