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    Subject[RFC][PATCH v2 05/13] usb: otg: add OTG core
    Date
    The OTG core instantiates the OTG Finite State Machine
    per OTG controller and manages starting/stopping the
    host and gadget controllers based on the bus state.

    It provides APIs for the following tasks

    - Registering an OTG capable controller
    - Registering Host and Gadget controllers to OTG core
    - Providing inputs to and kicking the OTG state machine

    TODO:
    - sysfs interface to allow application inputs to OTG state machine
    - otg class?

    Signed-off-by: Roger Quadros <rogerq@ti.com>
    ---
    drivers/usb/Makefile | 1 +
    drivers/usb/common/Makefile | 1 +
    drivers/usb/common/usb-otg.c | 743 +++++++++++++++++++++++++++++++++++++++++++
    drivers/usb/common/usb-otg.h | 71 +++++
    drivers/usb/core/Kconfig | 8 +
    include/linux/usb/usb-otg.h | 94 ++++++
    6 files changed, 918 insertions(+)
    create mode 100644 drivers/usb/common/usb-otg.c
    create mode 100644 drivers/usb/common/usb-otg.h
    create mode 100644 include/linux/usb/usb-otg.h

    diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
    index 2f1e2aa..07f59a5 100644
    --- a/drivers/usb/Makefile
    +++ b/drivers/usb/Makefile
    @@ -60,5 +60,6 @@ obj-$(CONFIG_USB_RENESAS_USBHS) += renesas_usbhs/
    obj-$(CONFIG_USB_GADGET) += gadget/

    obj-$(CONFIG_USB_COMMON) += common/
    +obj-$(CONFIG_USB_OTG_CORE) += common/

    obj-$(CONFIG_USBIP_CORE) += usbip/
    diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile
    index ca2f8bd..573fc75 100644
    --- a/drivers/usb/common/Makefile
    +++ b/drivers/usb/common/Makefile
    @@ -7,3 +7,4 @@ usb-common-y += common.o
    usb-common-$(CONFIG_USB_LED_TRIG) += led.o

    obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o
    +obj-$(CONFIG_USB_OTG_CORE) += usb-otg.o
    diff --git a/drivers/usb/common/usb-otg.c b/drivers/usb/common/usb-otg.c
    new file mode 100644
    index 0000000..e848e08
    --- /dev/null
    +++ b/drivers/usb/common/usb-otg.c
    @@ -0,0 +1,743 @@
    +/**
    + * drivers/usb/common/usb-otg.c - USB OTG core
    + *
    + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
    + * Author: Roger Quadros <rogerq@ti.com>
    + *
    + * 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 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.
    + */
    +
    +#include <linux/kernel.h>
    +#include <linux/ktime.h>
    +#include <linux/hrtimer.h>
    +#include <linux/list.h>
    +#include <linux/usb/otg.h>
    +#include <linux/usb/phy.h> /* enum usb_otg_state */
    +#include <linux/usb/gadget.h>
    +#include <linux/usb/usb-otg.h>
    +#include <linux/workqueue.h>
    +
    +#include "usb-otg.h"
    +
    +/* to link timer with callback data */
    +struct otg_timer {
    + struct hrtimer timer;
    + ktime_t timeout;
    + /* callback data */
    + int *timeout_bit;
    + struct otg_data *otgd;
    +};
    +
    +struct otg_hcd {
    + struct usb_hcd *hcd;
    + unsigned int irqnum;
    + unsigned long irqflags;
    +};
    +
    +struct otg_data {
    + struct device *dev; /* HCD & GCD's parent device */
    +
    + struct otg_fsm fsm;
    + /* HCD, GCD and usb_otg_state are present in otg_fsm->otg
    + * HCD is bus_to_hcd(fsm->otg->host)
    + * GCD is fsm->otg->gadget
    + */
    + struct otg_fsm_ops fsm_ops; /* private copy for override */
    + struct usb_otg otg; /* allocator for fsm->otg */
    +
    + struct otg_hcd primary_hcd;
    + struct otg_hcd shared_hcd;
    +
    + /* saved hooks to OTG device */
    + int (*start_host)(struct otg_fsm *fsm, int on);
    + int (*start_gadget)(struct otg_fsm *fsm, int on);
    +
    + struct list_head list;
    +
    + struct work_struct work; /* OTG FSM work */
    + struct workqueue_struct *wq;
    +
    + struct otg_timer timers[NUM_OTG_FSM_TIMERS];
    +
    + bool fsm_running;
    + /* use otg->fsm.lock for serializing access */
    +};
    +
    +/* OTG device list */
    +LIST_HEAD(otg_list);
    +static DEFINE_MUTEX(otg_list_mutex);
    +
    +/**
    + * check if device is in our OTG list and return
    + * otg_data, else NULL.
    + *
    + * otg_list_mutex must be held.
    + */
    +static struct otg_data *usb_otg_device_get_otgd(struct device *parent_dev)
    +{
    + struct otg_data *otgd;
    +
    + list_for_each_entry(otgd, &otg_list, list) {
    + if (otgd->dev == parent_dev)
    + return otgd;
    + }
    +
    + return NULL;
    +}
    +
    +/**
    + * timer callback to set timeout bit and kick FSM
    + */
    +static enum hrtimer_restart set_tmout(struct hrtimer *data)
    +{
    + struct otg_timer *otgtimer;
    +
    + otgtimer = container_of(data, struct otg_timer, timer);
    + if (otgtimer->timeout_bit)
    + *otgtimer->timeout_bit = 1;
    +
    + usb_otg_sync_inputs(&otgtimer->otgd->fsm);
    +
    + return HRTIMER_NORESTART;
    +}
    +
    +/**
    + * Initialize one OTG timer with callback, timeout and timeout bit
    + */
    +static void otg_timer_init(enum otg_fsm_timer id, struct otg_data *otgd,
    + enum hrtimer_restart (*callback)(struct hrtimer *),
    + unsigned long expires_ms,
    + int *timeout_bit)
    +{
    + struct otg_timer *otgtimer = &otgd->timers[id];
    + struct hrtimer *timer = &otgtimer->timer;
    +
    + otgtimer->timeout = ms_to_ktime(expires_ms);
    + hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
    + timer->function = callback;
    +
    + otgtimer->timeout_bit = timeout_bit;
    + otgtimer->otgd = otgd;
    +}
    +
    +/**
    + * Initialize standard OTG timers
    + */
    +static void usb_otg_init_timers(struct otg_data *otgd)
    +{
    + struct otg_fsm *fsm = &otgd->fsm;
    +
    + otg_timer_init(A_WAIT_VRISE, otgd, set_tmout, TA_WAIT_VRISE, &fsm->a_wait_vrise_tmout);
    + otg_timer_init(A_WAIT_VFALL, otgd, set_tmout, TA_WAIT_VFALL, &fsm->a_wait_vfall_tmout);
    + otg_timer_init(A_WAIT_BCON, otgd, set_tmout, TA_WAIT_BCON, &fsm->a_wait_bcon_tmout);
    + otg_timer_init(A_AIDL_BDIS, otgd, set_tmout, TA_AIDL_BDIS, &fsm->a_aidl_bdis_tmout);
    + otg_timer_init(A_BIDL_ADIS, otgd, set_tmout, TA_BIDL_ADIS, &fsm->a_bidl_adis_tmout);
    + otg_timer_init(B_ASE0_BRST, otgd, set_tmout, TB_ASE0_BRST, &fsm->b_ase0_brst_tmout);
    +
    + otg_timer_init(B_SE0_SRP, otgd, set_tmout, TB_SE0_SRP, &fsm->b_se0_srp);
    + otg_timer_init(B_SRP_FAIL, otgd, set_tmout, TB_SRP_FAIL, &fsm->b_srp_done);
    +
    + otg_timer_init(A_WAIT_ENUM, otgd, set_tmout, TB_SRP_FAIL, NULL);
    +}
    +
    +/**
    + * OTG FSM ops function to add timer
    + */
    +static void usb_otg_add_timer(struct otg_fsm *fsm, enum otg_fsm_timer id)
    +{
    + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
    + struct otg_timer *otgtimer = &otgd->timers[id];
    + struct hrtimer *timer = &otgtimer->timer;
    +
    + if (!otgd->fsm_running)
    + return;
    +
    + /* if timer is already active, exit */
    + if (hrtimer_active(timer)) {
    + dev_err(otgd->dev, "otg: timer %d is already running\n", id);
    + return;
    + }
    +
    + hrtimer_start(timer, otgtimer->timeout, HRTIMER_MODE_REL);
    +}
    +
    +/**
    + * OTG FSM ops function to delete timer
    + */
    +static void usb_otg_del_timer(struct otg_fsm *fsm, enum otg_fsm_timer id)
    +{
    + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
    + struct hrtimer *timer = &otgd->timers[id].timer;
    +
    + hrtimer_cancel(timer);
    +}
    +
    +/**
    + * OTG FSM ops function to start/stop host
    + */
    +static int usb_otg_start_host(struct otg_fsm *fsm, int on)
    +{
    + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
    +
    + dev_dbg(otgd->dev, "otg: %s %d\n", __func__, on);
    + if (!fsm->otg->host) {
    + WARN_ONCE(1, "otg: fsm running without host\n");
    + return 0;
    + }
    +
    + if (on) {
    + /* OTG device operations */
    + if (otgd->start_host)
    + otgd->start_host(fsm, on);
    +
    + /* start host */
    + usb_add_hcd(otgd->primary_hcd.hcd, otgd->primary_hcd.irqnum,
    + otgd->primary_hcd.irqflags);
    + if (otgd->shared_hcd.hcd) {
    + usb_add_hcd(otgd->shared_hcd.hcd,
    + otgd->shared_hcd.irqnum,
    + otgd->shared_hcd.irqflags);
    + }
    + } else {
    + /* stop host */
    + if (otgd->shared_hcd.hcd)
    + usb_remove_hcd(otgd->shared_hcd.hcd);
    + usb_remove_hcd(otgd->primary_hcd.hcd);
    +
    + /* OTG device operations */
    + if (otgd->start_host)
    + otgd->start_host(fsm, on);
    + }
    +
    + return 0;
    +}
    +
    +/**
    + * OTG FSM ops function to start/stop gadget
    + */
    +static int usb_otg_start_gadget(struct otg_fsm *fsm, int on)
    +{
    + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
    + struct usb_gadget *gadget = fsm->otg->gadget;
    +
    + dev_dbg(otgd->dev, "otg: %s %d\n", __func__, on);
    + if (!gadget) {
    + WARN_ONCE(1, "otg: fsm running without gadget\n");
    + return 0;
    + }
    +
    + if (on) {
    + /* OTG device operations */
    + if (otgd->start_gadget)
    + otgd->start_gadget(fsm, on);
    +
    + usb_gadget_start(fsm->otg->gadget);
    + } else {
    + usb_gadget_stop(fsm->otg->gadget);
    +
    + /* OTG device operations */
    + if (otgd->start_gadget)
    + otgd->start_gadget(fsm, on);
    +
    + }
    +
    + return 0;
    +}
    +
    +/**
    + * OTG FSM work function
    + */
    +static void usb_otg_work(struct work_struct *work)
    +{
    + struct otg_data *otgd = container_of(work, struct otg_data, work);
    +
    + if (otg_statemachine(&otgd->fsm)) {
    + /* state changed. any action ? */
    + }
    +}
    +
    +/**
    + * usb_otg_register() - Register the OTG device to OTG core
    + * @parent_device: parent device of Host & Gadget controllers.
    + * @otg_fsm_ops: otg state machine ops.
    + *
    + * Register parent device that contains both HCD and GCD into
    + * the USB OTG core. HCD and GCD will be prevented from starting
    + * till both are available for use.
    + *
    + * Return: struct otg_fsm * if success, NULL if error.
    + */
    +struct otg_fsm *usb_otg_register(struct device *parent_dev,
    + struct otg_fsm_ops *fsm_ops)
    +{
    + struct otg_data *otgd;
    + int ret = 0;
    +
    + if (!parent_dev || !fsm_ops)
    + return ERR_PTR(-EINVAL);
    +
    + /* already in list? */
    + mutex_lock(&otg_list_mutex);
    + if (usb_otg_device_get_otgd(parent_dev)) {
    + dev_err(parent_dev, "otg: %s: device already in otg list\n",
    + __func__);
    + ret = -EINVAL;
    + goto unlock;
    + }
    +
    + /* allocate and add to list */
    + otgd = kzalloc(sizeof(*otgd), GFP_KERNEL);
    + if (!otgd) {
    + ret = -ENOMEM;
    + goto unlock;
    + }
    +
    + otgd->dev = parent_dev;
    + INIT_WORK(&otgd->work, usb_otg_work);
    + otgd->wq = create_singlethread_workqueue("usb_otg");
    + if (!otgd->wq) {
    + dev_err(parent_dev, "otg: %s: can't create workqueue\n",
    + __func__);
    + ret = -ENODEV;
    + goto err_wq;
    + }
    +
    + usb_otg_init_timers(otgd);
    +
    + /* save original start host/gadget ops */
    + otgd->start_host = fsm_ops->start_host;
    + otgd->start_gadget = fsm_ops->start_gadget;
    + /* create copy of original ops */
    + otgd->fsm_ops = *fsm_ops;
    + /* override ops */
    + otgd->fsm_ops.start_host = usb_otg_start_host;
    + otgd->fsm_ops.start_gadget = usb_otg_start_gadget;
    + /* FIXME: we ignore caller's timer ops */
    + otgd->fsm_ops.add_timer = usb_otg_add_timer;
    + otgd->fsm_ops.del_timer = usb_otg_del_timer;
    + /* set otg ops */
    + otgd->fsm.ops = &otgd->fsm_ops;
    + otgd->fsm.otg = &otgd->otg;
    +
    + mutex_init(&otgd->fsm.lock);
    +
    + list_add_tail(&otgd->list, &otg_list);
    + mutex_unlock(&otg_list_mutex);
    + return &otgd->fsm;
    +
    +err_wq:
    + kfree(otgd);
    +unlock:
    + mutex_unlock(&otg_list_mutex);
    + return ERR_PTR(ret);
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_register);
    +
    +/**
    + * usb_otg_unregister() - Unregister the OTG device from USB OTG core
    + * @parent_device: parent device of Host & Gadget controllers.
    + *
    + * Unregister parent OTG deviced from USB OTG core.
    + * Prevents unregistering till both Host and Gadget controllers
    + * have unregistered from the OTG core.
    + *
    + * Return: 0 on success, error value otherwise.
    + */
    +int usb_otg_unregister(struct device *parent_dev)
    +{
    + struct otg_data *otgd;
    +
    + mutex_lock(&otg_list_mutex);
    + otgd = usb_otg_device_get_otgd(parent_dev);
    + if (!otgd) {
    + dev_err(parent_dev, "otg: %s: device not in otg list\n",
    + __func__);
    + mutex_unlock(&otg_list_mutex);
    + return -EINVAL;
    + }
    +
    + /* prevent unregister till both host & gadget have unregistered */
    + if (otgd->fsm.otg->host || otgd->fsm.otg->gadget) {
    + dev_err(parent_dev, "otg: %s: host/gadget still registered\n",
    + __func__);
    + return -EBUSY;
    + }
    +
    + /* OTG FSM is halted when host/gadget unregistered */
    + destroy_workqueue(otgd->wq);
    +
    + /* remove from otg list */
    + list_del(&otgd->list);
    + kfree(otgd);
    + mutex_unlock(&otg_list_mutex);
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_unregister);
    +
    +/**
    + * start/kick the OTG FSM if we can
    + * fsm->lock must be held
    + */
    +static void usb_otg_start_fsm(struct otg_fsm *fsm)
    +{
    + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
    +
    + if (otgd->fsm_running)
    + goto kick_fsm;
    +
    + if (!fsm->otg->host) {
    + dev_info(otgd->dev, "otg: can't start till host registers\n");
    + return;
    + }
    +
    + if (!fsm->otg->gadget) {
    + dev_info(otgd->dev, "otg: can't start till gadget registers\n");
    + return;
    + }
    +
    + otgd->fsm_running = true;
    +kick_fsm:
    + queue_work(otgd->wq, &otgd->work);
    +}
    +
    +/**
    + * stop the OTG FSM. Stops Host & Gadget controllers as well.
    + * fsm->lock must be held
    + */
    +static void usb_otg_stop_fsm(struct otg_fsm *fsm)
    +{
    + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
    + int i;
    +
    + if (!otgd->fsm_running)
    + return;
    +
    + /* no more new events queued */
    + otgd->fsm_running = false;
    +
    + /* Stop state machine / timers */
    + for (i = 0; i < ARRAY_SIZE(otgd->timers); i++)
    + hrtimer_cancel(&otgd->timers[i].timer);
    +
    + flush_workqueue(otgd->wq);
    + fsm->otg->state = OTG_STATE_UNDEFINED;
    +
    + /* stop host/gadget immediately */
    + if (fsm->protocol == PROTO_HOST)
    + otg_start_host(fsm, 0);
    + else if (fsm->protocol == PROTO_GADGET)
    + otg_start_gadget(fsm, 0);
    + fsm->protocol = PROTO_UNDEF;
    +}
    +
    +/**
    + * usb_otg_sync_inputs - Sync OTG inputs with the OTG state machine
    + * @fsm: OTG FSM instance
    + *
    + * Used by the OTG driver to update the inputs to the OTG
    + * state machine.
    + *
    + * Can be called in IRQ context.
    + */
    +void usb_otg_sync_inputs(struct otg_fsm *fsm)
    +{
    + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
    +
    + /* Don't kick FSM till it has started */
    + if (!otgd->fsm_running)
    + return;
    +
    + /* Kick FSM */
    + queue_work(otgd->wq, &otgd->work);
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_sync_inputs);
    +
    +/**
    + * usb_otg_kick_fsm - Kick the OTG state machine
    + * @hcd_gcd_device: Host/Gadget controller device
    + *
    + * Used by USB host/device stack to sync OTG related
    + * events to the OTG state machine.
    + * e.g. change in host_bus->b_hnp_enable, gadget->b_hnp_enable
    + *
    + * Returns: 0 on success, error value otherwise.
    + */
    +int usb_otg_kick_fsm(struct device *hcd_gcd_device)
    +{
    + struct otg_data *otgd;
    +
    + mutex_lock(&otg_list_mutex);
    + otgd = usb_otg_device_get_otgd(hcd_gcd_device->parent);
    + if (!otgd) {
    + dev_err(hcd_gcd_device, "otg: %s: invalid host/gadget device\n",
    + __func__);
    + mutex_unlock(&otg_list_mutex);
    + return -ENODEV;
    + }
    +
    + mutex_unlock(&otg_list_mutex);
    + usb_otg_sync_inputs(&otgd->fsm);
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_kick_fsm);
    +
    +/**
    + * usb_otg_register_hcd - Register Host controller to OTG core
    + * @hcd: Host controller device
    + *
    + * This is used by the USB Host stack to register the Host controller
    + * to the OTG core. Host controller must not be started by the
    + * caller as it is left upto the OTG state machine to do so.
    + *
    + * Returns: 0 on success, error value otherwise.
    + */
    +int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum,
    + unsigned long irqflags)
    +{
    + struct otg_data *otgd;
    + struct device *otg_dev = hcd->self.controller->parent;
    +
    + mutex_lock(&otg_list_mutex);
    + otgd = usb_otg_device_get_otgd(otg_dev);
    + if (!otgd) {
    + dev_dbg(otg_dev, "otg: %s: device not registered to otg core\n",
    + __func__);
    + mutex_unlock(&otg_list_mutex);
    + return -EINVAL;
    + }
    +
    + mutex_unlock(&otg_list_mutex);
    + /* HCD will be started by OTG fsm when needed */
    + mutex_lock(&otgd->fsm.lock);
    + if (otgd->primary_hcd.hcd) {
    + /* probably a shared HCD ? */
    + if (usb_hcd_is_primary_hcd(hcd)) {
    + dev_err(otg_dev, "otg: primary host already registered\n");
    + goto err;
    + }
    +
    + if (hcd->shared_hcd == otgd->primary_hcd.hcd) {
    + if (otgd->shared_hcd.hcd) {
    + dev_err(otg_dev, "otg: shared host already registered\n");
    + goto err;
    + }
    +
    + otgd->shared_hcd.hcd = hcd;
    + otgd->shared_hcd.irqnum = irqnum;
    + otgd->shared_hcd.irqflags = irqflags;
    + dev_info(otg_dev, "otg: shared host %s registered\n",
    + dev_name(hcd->self.controller));
    + } else {
    + dev_err(otg_dev, "otg: invalid shared host %s\n",
    + dev_name(hcd->self.controller));
    + goto err;
    + }
    + } else {
    + if (!usb_hcd_is_primary_hcd(hcd)) {
    + dev_err(otg_dev, "otg: primary host must be registered first\n");
    + goto err;
    + }
    +
    + otgd->primary_hcd.hcd = hcd;
    + otgd->primary_hcd.irqnum = irqnum;
    + otgd->primary_hcd.irqflags = irqflags;
    + dev_info(otg_dev, "otg: primary host %s registered\n",
    + dev_name(hcd->self.controller));
    +
    + }
    +
    + /*
    + * we're ready only if we have shared HCD
    + * or we don't need shared HCD.
    + */
    + if (otgd->shared_hcd.hcd || !otgd->primary_hcd.hcd->shared_hcd) {
    + otgd->fsm.otg->host = hcd_to_bus(hcd);
    + /* FIXME: set bus->otg_port if this is true OTG port with HNP */
    +
    + /* start FSM */
    + usb_otg_start_fsm(&otgd->fsm);
    + } else {
    + dev_dbg(otg_dev, "otg: can't start till shared host registers\n");
    + }
    +
    + mutex_unlock(&otgd->fsm.lock);
    +
    + return 0;
    +
    +err:
    + mutex_unlock(&otgd->fsm.lock);
    + return -EINVAL;
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_register_hcd);
    +
    +/**
    + * usb_otg_unregister_hcd - Unregister Host controller from OTG core
    + * @hcd: Host controller device
    + *
    + * This is used by the USB Host stack to unregister the Host controller
    + * from the OTG core. Ensures that Host controller is not running
    + * on successful return.
    + *
    + * Returns: 0 on success, error value otherwise.
    + */
    +int usb_otg_unregister_hcd(struct usb_hcd *hcd)
    +{
    + struct otg_data *otgd;
    + struct usb_bus *bus = hcd_to_bus(hcd);
    + struct device *otg_dev = bus->controller->parent;
    +
    + mutex_lock(&otg_list_mutex);
    + otgd = usb_otg_device_get_otgd(otg_dev);
    + if (!otgd) {
    + dev_err(otg_dev, "otg: %s: device not registered to otg core\n",
    + __func__);
    + mutex_unlock(&otg_list_mutex);
    + return -EINVAL;
    + }
    +
    + mutex_unlock(&otg_list_mutex);
    +
    + mutex_lock(&otgd->fsm.lock);
    + if (hcd == otgd->primary_hcd.hcd) {
    + otgd->primary_hcd.hcd = NULL;
    + dev_info(otg_dev, "otg: primary host %s unregistered\n",
    + dev_name(bus->controller));
    + } else if (hcd == otgd->shared_hcd.hcd) {
    + otgd->shared_hcd.hcd = NULL;
    + dev_info(otg_dev, "otg: shared host %s unregistered\n",
    + dev_name(bus->controller));
    + } else {
    + dev_err(otg_dev, "otg: host %s wasn't registered with otg\n",
    + dev_name(bus->controller));
    + mutex_unlock(&otgd->fsm.lock);
    + return -EINVAL;
    + }
    +
    + /* stop FSM & Host */
    + usb_otg_stop_fsm(&otgd->fsm);
    + otgd->fsm.otg->host = NULL;
    +
    + mutex_unlock(&otgd->fsm.lock);
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_unregister_hcd);
    +
    +/**
    + * usb_otg_register_gadget - Register Gadget controller to OTG core
    + * @gadget: Gadget controller
    + *
    + * This is used by the USB Gadget stack to register the Gadget controller
    + * to the OTG core. Gadget controller must not be started by the
    + * caller as it is left upto the OTG state machine to do so.
    + *
    + * Gadget core must call this only when all resources required for
    + * gadget controller to run are available.
    + * i.e. gadget function driver is available.
    + *
    + * Returns: 0 on success, error value otherwise.
    + */
    +int usb_otg_register_gadget(struct usb_gadget *gadget)
    +{
    + struct otg_data *otgd;
    + struct device *otg_dev = gadget->dev.parent;
    +
    + mutex_lock(&otg_list_mutex);
    + otgd = usb_otg_device_get_otgd(otg_dev);
    + if (!otgd) {
    + dev_err(otg_dev, "otg: %s: device not registered to otg core\n",
    + __func__);
    + mutex_unlock(&otg_list_mutex);
    + return -EINVAL;
    + }
    +
    + mutex_unlock(&otg_list_mutex);
    +
    + mutex_lock(&otgd->fsm.lock);
    + if (otgd->fsm.otg->gadget) {
    + dev_err(otg_dev, "otg: gadget already registered with otg\n");
    + mutex_unlock(&otgd->fsm.lock);
    + return -EINVAL;
    + }
    +
    + otgd->fsm.otg->gadget = gadget;
    + dev_info(otg_dev, "otg: gadget %s registered\n",
    + dev_name(&gadget->dev));
    +
    + /* start FSM */
    + usb_otg_start_fsm(&otgd->fsm);
    + mutex_unlock(&otgd->fsm.lock);
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_register_gadget);
    +
    +/**
    + * usb_otg_unregister_gadget - Unregister Gadget controller from OTG core
    + * @gadget: Gadget controller
    + *
    + * This is used by the USB Gadget stack to unregister the Gadget controller
    + * from the OTG core. Ensures that Gadget controller is not running
    + * on successful return.
    + *
    + * Returns: 0 on success, error value otherwise.
    + */
    +int usb_otg_unregister_gadget(struct usb_gadget *gadget)
    +{
    + struct otg_data *otgd;
    + struct device *otg_dev = gadget->dev.parent;
    +
    + mutex_lock(&otg_list_mutex);
    + otgd = usb_otg_device_get_otgd(otg_dev);
    + if (!otgd) {
    + dev_err(otg_dev, "otg: %s: device not registered to otg core\n",
    + __func__);
    + mutex_unlock(&otg_list_mutex);
    + return -EINVAL;
    + }
    +
    + mutex_unlock(&otg_list_mutex);
    +
    + mutex_lock(&otgd->fsm.lock);
    + if (otgd->fsm.otg->gadget != gadget) {
    + dev_err(otg_dev, "otg: gadget %s wasn't registered with otg\n",
    + dev_name(&gadget->dev));
    + mutex_unlock(&otgd->fsm.lock);
    + return -EINVAL;
    + }
    +
    + /* Stop FSM & gadget */
    + usb_otg_stop_fsm(&otgd->fsm);
    + otgd->fsm.otg->gadget = NULL;
    + mutex_unlock(&otgd->fsm.lock);
    +
    + dev_info(otg_dev, "otg: gadget %s unregistered\n",
    + dev_name(&gadget->dev));
    +
    + return 0;
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_unregister_gadget);
    +
    +/**
    + * usb_otg_fsm_to_dev - Get OTG controller device from struct otg_fsm
    + * @fsm: otg_fsm data structure
    + *
    + * This is used by the OTG controller driver to get it's device node
    + * from any of the otg_fsm->ops.
    + */
    +struct device *usb_otg_fsm_to_dev(struct otg_fsm *fsm)
    +{
    + struct otg_data *otgd = container_of(fsm, struct otg_data, fsm);
    +
    + return otgd->dev;
    +}
    +EXPORT_SYMBOL_GPL(usb_otg_fsm_to_dev);
    diff --git a/drivers/usb/common/usb-otg.h b/drivers/usb/common/usb-otg.h
    new file mode 100644
    index 0000000..05331f0
    --- /dev/null
    +++ b/drivers/usb/common/usb-otg.h
    @@ -0,0 +1,71 @@
    +/**
    + * drivers/usb/common/usb-otg.h - USB OTG core local header
    + *
    + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
    + * Author: Roger Quadros <rogerq@ti.com>
    + *
    + * 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 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.
    + */
    +
    +#ifndef __DRIVERS_USB_COMMON_USB_OTG_H
    +#define __DRIVERS_USB_COMMON_USB_OTG_H
    +
    +/*
    + * A-DEVICE timing constants
    + */
    +
    +/* Wait for VBUS Rise */
    +#define TA_WAIT_VRISE (100) /* a_wait_vrise: section 7.1.2
    + * a_wait_vrise_tmr: section 7.4.5.1
    + * TA_VBUS_RISE <= 100ms, section 4.4
    + * Table 4-1: Electrical Characteristics
    + * ->DC Electrical Timing
    + */
    +/* Wait for VBUS Fall */
    +#define TA_WAIT_VFALL (1000) /* a_wait_vfall: section 7.1.7
    + * a_wait_vfall_tmr: section: 7.4.5.2
    + */
    +/* Wait for B-Connect */
    +#define TA_WAIT_BCON (10000) /* a_wait_bcon: section 7.1.3
    + * TA_WAIT_BCON: should be between 1100
    + * and 30000 ms, section 5.5, Table 5-1
    + */
    +/* A-Idle to B-Disconnect */
    +#define TA_AIDL_BDIS (5000) /* a_suspend min 200 ms, section 5.2.1
    + * TA_AIDL_BDIS: section 5.5, Table 5-1
    + */
    +/* B-Idle to A-Disconnect */
    +#define TA_BIDL_ADIS (500) /* TA_BIDL_ADIS: section 5.2.1
    + * 500ms is used for B switch to host
    + * for safe
    + */
    +
    +/*
    + * B-device timing constants
    + */
    +
    +/* Data-Line Pulse Time*/
    +#define TB_DATA_PLS (10) /* b_srp_init,continue 5~10ms
    + * section:5.1.3
    + */
    +/* SRP Fail Time */
    +#define TB_SRP_FAIL (6000) /* b_srp_init,fail time 5~6s
    + * section:5.1.6
    + */
    +/* A-SE0 to B-Reset */
    +#define TB_ASE0_BRST (155) /* minimum 155 ms, section:5.3.1 */
    +/* SE0 Time Before SRP */
    +#define TB_SE0_SRP (1000) /* b_idle,minimum 1s, section:5.1.2 */
    +/* SSEND time before SRP */
    +#define TB_SSEND_SRP (1500) /* minimum 1.5 sec, section:5.1.2 */
    +
    +#define TB_SESS_VLD (1000)
    +
    +#endif /* __DRIVERS_USB_COMMON_USB_OTG_H */
    diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
    index cc0ced0..43a0d2d 100644
    --- a/drivers/usb/core/Kconfig
    +++ b/drivers/usb/core/Kconfig
    @@ -84,3 +84,11 @@ config USB_OTG_FSM
    Implements OTG Finite State Machine as specified in On-The-Go
    and Embedded Host Supplement to the USB Revision 2.0 Specification.

    +config USB_OTG_CORE
    + tristate "USB OTG core"
    + depends on USB
    + select USB_OTG_FSM
    + help
    + Standardize the way OTG is implemented on Linux. The OTG state
    + machine is instantiated here instead of being done in each controller
    + driver.
    diff --git a/include/linux/usb/usb-otg.h b/include/linux/usb/usb-otg.h
    new file mode 100644
    index 0000000..8987cd1
    --- /dev/null
    +++ b/include/linux/usb/usb-otg.h
    @@ -0,0 +1,94 @@
    +/**
    + * include/linux/usb/usb-otg.h - USB OTG core
    + *
    + * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com
    + * Author: Roger Quadros <rogerq@ti.com>
    + *
    + * 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 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.
    + */
    +
    +#ifndef __LINUX_USB_OTG_CORE_H
    +#define __LINUX_USB_OTG_CORE_H
    +
    +#include <linux/device.h>
    +#include <linux/usb.h>
    +#include <linux/usb/hcd.h>
    +#include <linux/usb/gadget.h>
    +#include <linux/usb/otg-fsm.h>
    +
    +#if IS_ENABLED(CONFIG_USB_OTG_CORE)
    +struct otg_fsm *usb_otg_register(struct device *parent_dev,
    + struct otg_fsm_ops *fsm_ops);
    +int usb_otg_unregister(struct device *parent_dev);
    +int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum,
    + unsigned long irqflags);
    +int usb_otg_unregister_hcd(struct usb_hcd *hcd);
    +int usb_otg_register_gadget(struct usb_gadget *gadget);
    +int usb_otg_unregister_gadget(struct usb_gadget *gadget);
    +void usb_otg_sync_inputs(struct otg_fsm *fsm);
    +int usb_otg_kick_fsm(struct device *hcd_gcd_device);
    +bool usb_otg_gadget_can_start(struct usb_gadget *gadget);
    +struct device *usb_otg_fsm_to_dev(struct otg_fsm *fsm);
    +
    +#else /* CONFIG_USB_OTG_CORE */
    +
    +static inline struct otg_fsm *usb_otg_register(struct device *parent_dev,
    + struct otg_fsm_ops *fsm_ops)
    +{
    + return ERR_PTR(-ENOSYS);
    +}
    +
    +static inline int usb_otg_unregister(struct device *parent_dev)
    +{
    + return -ENOSYS;
    +}
    +
    +static inline int usb_otg_register_hcd(struct usb_hcd *hcd, unsigned int irqnum,
    + unsigned long irqflags)
    +{
    + return -ENOSYS;
    +}
    +
    +int usb_otg_unregister_hcd(struct usb_hcd *hcd)
    +{
    + return -ENOSYS;
    +}
    +
    +static inline int usb_otg_register_gadget(struct usb_gadget *gadget)
    +{
    + return -ENOSYS;
    +}
    +
    +static inline int usb_otg_unregister_gadget(struct usb_gadget *gadget)
    +{
    + return -ENOSYS;
    +}
    +
    +static inline void usb_otg_sync_inputs(struct otg_fsm *fsm)
    +{
    +}
    +
    +int usb_otg_kick_fsm(struct device *hcd_gcd_device)
    +{
    + return -ENOSYS;
    +}
    +
    +bool usb_otg_gadget_can_start(struct usb_gadget *gadget)
    +{
    + return true;
    +}
    +
    +static inline struct device *usb_otg_fsm_to_dev(struct otg_fsm *fsm)
    +{
    + return NULL;
    +}
    +#endif /* CONFIG_USB_OTG_CORE */
    +
    +#endif /* __LINUX_USB_OTG_CORE */
    --
    2.1.0


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