/**
 * udc.c - Core UDC Framework
 *
 * Copyright (C) 2010 Texas Instruments
 * Author: Felipe Balbi <balbi@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  of
 * the License 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/err.h>
#include <linux/dma-mapping.h>
#include <linux/workqueue.h>

#include <linux/usb/ch9.h>
#include <linux/usb/gadget.h>
#include <linux/usb.h>

/**
 * struct usb_udc - describes one usb device controller
 * @driver - the gadget driver pointer. For use by the class code
 * @dev - the child device to the actual controller
 * @gadget - the gadget. For use by the class code
 * @list - for use by the udc class driver
 * @vbus - for udcs who care about vbus status, this value is real vbus status;
 * for udcs who do not care about vbus status, this value is always true
 *
 * This represents the internal data structure which is used by the UDC-class
 * to hold information about udc driver and gadget together.
 */
struct usb_udc {
        struct usb_gadget_driver        *driver;
        struct usb_gadget               *gadget;
        struct device                   dev;
        struct list_head                list;
        bool                            vbus;
};

static struct class *udc_class;
static LIST_HEAD(udc_list);
static DEFINE_MUTEX(udc_lock);

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

#ifdef  CONFIG_HAS_DMA

int usb_gadget_map_request(struct usb_gadget *gadget,
                struct usb_request *req, int is_in)
{
        struct device *dev = gadget->dev.parent;

        if (req->length == 0)
                return 0;

        if (req->num_sgs) {
                int     mapped;

                mapped = dma_map_sg(dev, req->sg, req->num_sgs,
                                is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
                if (mapped == 0) {
                        dev_err(&gadget->dev, "failed to map SGs\n");
                        return -EFAULT;
                }

                req->num_mapped_sgs = mapped;
        } else {
                req->dma = dma_map_single(dev, req->buf, req->length,
                                is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);

                if (dma_mapping_error(dev, req->dma)) {
                        dev_err(dev, "failed to map buffer\n");
                        return -EFAULT;
                }
        }

        return 0;
}
EXPORT_SYMBOL_GPL(usb_gadget_map_request);

void usb_gadget_unmap_request(struct usb_gadget *gadget,
                struct usb_request *req, int is_in)
{
        if (req->length == 0)
                return;

        if (req->num_mapped_sgs) {
                dma_unmap_sg(gadget->dev.parent, req->sg, req->num_mapped_sgs,
                                is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);

                req->num_mapped_sgs = 0;
        } else {
                dma_unmap_single(gadget->dev.parent, req->dma, req->length,
                                is_in ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
        }
}
EXPORT_SYMBOL_GPL(usb_gadget_unmap_request);

#endif  /* CONFIG_HAS_DMA */

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

/**
 * usb_gadget_giveback_request - give the request back to the gadget layer
 * Context: in_interrupt()
 *
 * This is called by device controller drivers in order to return the
 * completed request back to the gadget layer.
 */
void usb_gadget_giveback_request(struct usb_ep *ep,
                struct usb_request *req)
{
        if (likely(req->status == 0))
                usb_led_activity(USB_LED_EVENT_GADGET);

        req->complete(ep, req);
}
EXPORT_SYMBOL_GPL(usb_gadget_giveback_request);

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

static void usb_gadget_state_work(struct work_struct *work)
{
        struct usb_gadget *gadget = work_to_gadget(work);
        struct usb_udc *udc = gadget->udc;

        if (udc)
                sysfs_notify(&udc->dev.kobj, NULL, "state");
}

void usb_gadget_set_state(struct usb_gadget *gadget,
                enum usb_device_state state)
{
        gadget->state = state;
        schedule_work(&gadget->work);
}
EXPORT_SYMBOL_GPL(usb_gadget_set_state);

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

static void usb_udc_connect_control(struct usb_udc *udc)
{
        if (udc->vbus)
                usb_gadget_connect(udc->gadget);
        else
                usb_gadget_disconnect(udc->gadget);
}

/**
 * usb_udc_vbus_handler - updates the udc core vbus status, and try to
 * connect or disconnect gadget
 * @gadget: The gadget which vbus change occurs
 * @status: The vbus status
 *
 * The udc driver calls it when it wants to connect or disconnect gadget
 * according to vbus status.
 */
void usb_udc_vbus_handler(struct usb_gadget *gadget, bool status)
{
        struct usb_udc *udc = gadget->udc;

        if (udc) {
                udc->vbus = status;
                usb_udc_connect_control(udc);
        }
}
EXPORT_SYMBOL_GPL(usb_udc_vbus_handler);

/**
 * usb_gadget_udc_reset - notifies the udc core that bus reset occurs
 * @gadget: The gadget which bus reset occurs
 * @driver: The gadget driver we want to notify
 *
 * If the udc driver has bus reset handler, it needs to call this when the bus
 * reset occurs, it notifies the gadget driver that the bus reset occurs as
 * well as updates gadget state.
 */
void usb_gadget_udc_reset(struct usb_gadget *gadget,
                struct usb_gadget_driver *driver)
{
        driver->reset(gadget);
        usb_gadget_set_state(gadget, USB_STATE_DEFAULT);
}
EXPORT_SYMBOL_GPL(usb_gadget_udc_reset);

/**
 * usb_gadget_udc_start - tells usb device controller to start up
 * @udc: The UDC to be started
 *
 * This call is issued by the UDC Class driver when it's about
 * to register a gadget driver to the device controller, before
 * calling gadget driver's bind() method.
 *
 * It allows the controller to be powered off until strictly
 * necessary to have it powered on.
 *
 * Returns zero on success, else negative errno.
 */
static inline int usb_gadget_udc_start(struct usb_udc *udc)
{
        return udc->gadget->ops->udc_start(udc->gadget, udc->driver);
}

/**
 * usb_gadget_udc_stop - tells usb device controller we don't need it anymore
 * @gadget: The device we want to stop activity
 * @driver: The driver to unbind from @gadget
 *
 * This call is issued by the UDC Class driver after calling
 * gadget driver's unbind() method.
 *
 * The details are implementation specific, but it can go as
 * far as powering off UDC completely and disable its data
 * line pullups.
 */
static inline void usb_gadget_udc_stop(struct usb_udc *udc)
{
        udc->gadget->ops->udc_stop(udc->gadget);
}

/**
 * usb_udc_release - release the usb_udc struct
 * @dev: the dev member within usb_udc
 *
 * This is called by driver's core in order to free memory once the last
 * reference is released.
 */
static void usb_udc_release(struct device *dev)
{
        struct usb_udc *udc;

        udc = container_of(dev, struct usb_udc, dev);
        dev_dbg(dev, "releasing '%s'\n", dev_name(dev));
        kfree(udc);
}

static const struct attribute_group *usb_udc_attr_groups[];

static void usb_udc_nop_release(struct device *dev)
{
        dev_vdbg(dev, "%s\n", __func__);
}

/**
 * usb_add_gadget_udc_release - adds a new gadget to the udc class driver list
 * @parent: the parent device to this udc. Usually the controller driver's
 * device.
 * @gadget: the gadget to be added to the list.
 * @release: a gadget release function.
 *
 * Returns zero on success, negative errno otherwise.
 */
int usb_add_gadget_udc_release(struct device *parent, struct usb_gadget *gadget,
                void (*release)(struct device *dev))
{
        struct usb_udc          *udc;
        int                     ret = -ENOMEM;

        udc = kzalloc(sizeof(*udc), GFP_KERNEL);
        if (!udc)
                goto err1;

        dev_set_name(&gadget->dev, "gadget");
        INIT_WORK(&gadget->work, usb_gadget_state_work);
        gadget->dev.parent = parent;

#ifdef  CONFIG_HAS_DMA
        dma_set_coherent_mask(&gadget->dev, parent->coherent_dma_mask);
        gadget->dev.dma_parms = parent->dma_parms;
        gadget->dev.dma_mask = parent->dma_mask;
#endif

        if (release)
                gadget->dev.release = release;
        else
                gadget->dev.release = usb_udc_nop_release;

        ret = device_register(&gadget->dev);
        if (ret)
                goto err2;

        device_initialize(&udc->dev);
        udc->dev.release = usb_udc_release;
        udc->dev.class = udc_class;
        udc->dev.groups = usb_udc_attr_groups;
        udc->dev.parent = parent;
        ret = dev_set_name(&udc->dev, "%s", kobject_name(&parent->kobj));
        if (ret)
                goto err3;

        udc->gadget = gadget;
        gadget->udc = udc;

        mutex_lock(&udc_lock);
        list_add_tail(&udc->list, &udc_list);

        ret = device_add(&udc->dev);
        if (ret)
                goto err4;

        usb_gadget_set_state(gadget, USB_STATE_NOTATTACHED);
        udc->vbus = true;

        mutex_unlock(&udc_lock);

        return 0;

err4:
        list_del(&udc->list);
        mutex_unlock(&udc_lock);

err3:
        put_device(&udc->dev);
        device_del(&gadget->dev);

err2:
        put_device(&gadget->dev);
        kfree(udc);

err1:
        return ret;
}
EXPORT_SYMBOL_GPL(usb_add_gadget_udc_release);

/**
 * usb_add_gadget_udc - adds a new gadget to the udc class driver list
 * @parent: the parent device to this udc. Usually the controller
 * driver's device.
 * @gadget: the gadget to be added to the list
 *
 * Returns zero on success, negative errno otherwise.
 */
int usb_add_gadget_udc(struct device *parent, struct usb_gadget *gadget)
{
        return usb_add_gadget_udc_release(parent, gadget, NULL);
}
EXPORT_SYMBOL_GPL(usb_add_gadget_udc);

static void usb_gadget_remove_driver(struct usb_udc *udc)
{
        dev_dbg(&udc->dev, "unregistering UDC driver [%s]\n",
                        udc->driver->function);

        kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);

        usb_gadget_disconnect(udc->gadget);
        udc->driver->disconnect(udc->gadget);
        udc->driver->unbind(udc->gadget);
        usb_gadget_udc_stop(udc);

        udc->driver = NULL;
        udc->dev.driver = NULL;
        udc->gadget->dev.driver = NULL;
}

/**
 * usb_del_gadget_udc - deletes @udc from udc_list
 * @gadget: the gadget to be removed.
 *
 * This, will call usb_gadget_unregister_driver() if
 * the @udc is still busy.
 */
void usb_del_gadget_udc(struct usb_gadget *gadget)
{
        struct usb_udc *udc = gadget->udc;

        if (!udc)
                return;

        dev_vdbg(gadget->dev.parent, "unregistering gadget\n");

        mutex_lock(&udc_lock);
        list_del(&udc->list);
        mutex_unlock(&udc_lock);

        if (udc->driver)
                usb_gadget_remove_driver(udc);

        kobject_uevent(&udc->dev.kobj, KOBJ_REMOVE);
        flush_work(&gadget->work);
        device_unregister(&udc->dev);
        device_unregister(&gadget->dev);
}
EXPORT_SYMBOL_GPL(usb_del_gadget_udc);

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

static int udc_bind_to_driver(struct usb_udc *udc, struct usb_gadget_driver *driver)
{
        int ret;

        dev_dbg(&udc->dev, "registering UDC driver [%s]\n",
                        driver->function);

        udc->driver = driver;
        udc->dev.driver = &driver->driver;
        udc->gadget->dev.driver = &driver->driver;

        ret = driver->bind(udc->gadget, driver);
        if (ret)
                goto err1;
        ret = usb_gadget_udc_start(udc);
        if (ret) {
                driver->unbind(udc->gadget);
                goto err1;
        }
        usb_udc_connect_control(udc);

        kobject_uevent(&udc->dev.kobj, KOBJ_CHANGE);
        return 0;
err1:
        if (ret != -EISNAM)
                dev_err(&udc->dev, "failed to start %s: %d\n",
                        udc->driver->function, ret);
        udc->driver = NULL;
        udc->dev.driver = NULL;
        udc->gadget->dev.driver = NULL;
        return ret;
}

int usb_udc_attach_driver(const char *name, struct usb_gadget_driver *driver)
{
        struct usb_udc *udc = NULL;
        int ret = -ENODEV;

        mutex_lock(&udc_lock);
        list_for_each_entry(udc, &udc_list, list) {
                ret = strcmp(name, dev_name(&udc->dev));
                if (!ret)
                        break;
        }
        if (ret) {
                ret = -ENODEV;
                goto out;
        }
        if (udc->driver) {
                ret = -EBUSY;
                goto out;
        }
        ret = udc_bind_to_driver(udc, driver);
out:
        mutex_unlock(&udc_lock);
        return ret;
}
EXPORT_SYMBOL_GPL(usb_udc_attach_driver);

int usb_gadget_probe_driver(struct usb_gadget_driver *driver)
{
        struct usb_udc          *udc = NULL;
        int                     ret;

        if (!driver || !driver->bind || !driver->setup)
                return -EINVAL;

        mutex_lock(&udc_lock);
        list_for_each_entry(udc, &udc_list, list) {
                /* For now we take the first one */
                if (!udc->driver)
                        goto found;
        }

        pr_debug("couldn't find an available UDC\n");
        mutex_unlock(&udc_lock);
        return -ENODEV;
found:
        ret = udc_bind_to_driver(udc, driver);
        mutex_unlock(&udc_lock);
        return ret;
}
EXPORT_SYMBOL_GPL(usb_gadget_probe_driver);

int usb_gadget_unregister_driver(struct usb_gadget_driver *driver)
{
        struct usb_udc          *udc = NULL;
        int                     ret = -ENODEV;

        if (!driver || !driver->unbind)
                return -EINVAL;

        mutex_lock(&udc_lock);
        list_for_each_entry(udc, &udc_list, list)
                if (udc->driver == driver) {
                        usb_gadget_remove_driver(udc);
                        usb_gadget_set_state(udc->gadget,
                                        USB_STATE_NOTATTACHED);
                        ret = 0;
                        break;
                }

        mutex_unlock(&udc_lock);
        return ret;
}
EXPORT_SYMBOL_GPL(usb_gadget_unregister_driver);

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

static ssize_t usb_udc_srp_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t n)
{
        struct usb_udc          *udc = container_of(dev, struct usb_udc, dev);

        if (sysfs_streq(buf, "1"))
                usb_gadget_wakeup(udc->gadget);

        return n;
}
static DEVICE_ATTR(srp, S_IWUSR, NULL, usb_udc_srp_store);

static ssize_t usb_udc_softconn_store(struct device *dev,
                struct device_attribute *attr, const char *buf, size_t n)
{
        struct usb_udc          *udc = container_of(dev, struct usb_udc, dev);

        if (!udc->driver) {
                dev_err(dev, "soft-connect without a gadget driver\n");
                return -EOPNOTSUPP;
        }

        if (sysfs_streq(buf, "connect")) {
                usb_gadget_udc_start(udc);
                usb_gadget_connect(udc->gadget);
        } else if (sysfs_streq(buf, "disconnect")) {
                usb_gadget_disconnect(udc->gadget);
                udc->driver->disconnect(udc->gadget);
                usb_gadget_udc_stop(udc);
        } else {
                dev_err(dev, "unsupported command '%s'\n", buf);
                return -EINVAL;
        }

        return n;
}
static DEVICE_ATTR(soft_connect, S_IWUSR, NULL, usb_udc_softconn_store);

static ssize_t state_show(struct device *dev, struct device_attribute *attr,
                          char *buf)
{
        struct usb_udc          *udc = container_of(dev, struct usb_udc, dev);
        struct usb_gadget       *gadget = udc->gadget;

        return sprintf(buf, "%s\n", usb_state_string(gadget->state));
}
static DEVICE_ATTR_RO(state);

#define USB_UDC_SPEED_ATTR(name, param)                                 \
ssize_t name##_show(struct device *dev,                                 \
                struct device_attribute *attr, char *buf)               \
{                                                                       \
        struct usb_udc *udc = container_of(dev, struct usb_udc, dev);   \
        return snprintf(buf, PAGE_SIZE, "%s\n",                         \
                        usb_speed_string(udc->gadget->param));          \
}                                                                       \
static DEVICE_ATTR_RO(name)

static USB_UDC_SPEED_ATTR(current_speed, speed);
static USB_UDC_SPEED_ATTR(maximum_speed, max_speed);

#define USB_UDC_ATTR(name)                                      \
ssize_t name##_show(struct device *dev,                         \
                struct device_attribute *attr, char *buf)       \
{                                                               \
        struct usb_udc          *udc = container_of(dev, struct usb_udc, dev); \
        struct usb_gadget       *gadget = udc->gadget;          \
                                                                \
        return snprintf(buf, PAGE_SIZE, "%d\n", gadget->name);  \
}                                                               \
static DEVICE_ATTR_RO(name)

static USB_UDC_ATTR(is_otg);
static USB_UDC_ATTR(is_a_peripheral);
static USB_UDC_ATTR(b_hnp_enable);
static USB_UDC_ATTR(a_hnp_support);
static USB_UDC_ATTR(a_alt_hnp_support);
static USB_UDC_ATTR(is_selfpowered);

static struct attribute *usb_udc_attrs[] = {
        &dev_attr_srp.attr,
        &dev_attr_soft_connect.attr,
        &dev_attr_state.attr,
        &dev_attr_current_speed.attr,
        &dev_attr_maximum_speed.attr,

        &dev_attr_is_otg.attr,
        &dev_attr_is_a_peripheral.attr,
        &dev_attr_b_hnp_enable.attr,
        &dev_attr_a_hnp_support.attr,
        &dev_attr_a_alt_hnp_support.attr,
        &dev_attr_is_selfpowered.attr,
        NULL,
};

static const struct attribute_group usb_udc_attr_group = {
        .attrs = usb_udc_attrs,
};

static const struct attribute_group *usb_udc_attr_groups[] = {
        &usb_udc_attr_group,
        NULL,
};

static int usb_udc_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        struct usb_udc          *udc = container_of(dev, struct usb_udc, dev);
        int                     ret;

        ret = add_uevent_var(env, "USB_UDC_NAME=%s", udc->gadget->name);
        if (ret) {
                dev_err(dev, "failed to add uevent USB_UDC_NAME\n");
                return ret;
        }

        if (udc->driver) {
                ret = add_uevent_var(env, "USB_UDC_DRIVER=%s",
                                udc->driver->function);
                if (ret) {
                        dev_err(dev, "failed to add uevent USB_UDC_DRIVER\n");
                        return ret;
                }
        }

        return 0;
}

static int __init usb_udc_init(void)
{
        udc_class = class_create(THIS_MODULE, "udc");
        if (IS_ERR(udc_class)) {
                pr_err("failed to create udc class --> %ld\n",
                                PTR_ERR(udc_class));
                return PTR_ERR(udc_class);
        }

        udc_class->dev_uevent = usb_udc_uevent;
        return 0;
}
subsys_initcall(usb_udc_init);

static void __exit usb_udc_exit(void)
{
        class_destroy(udc_class);
}
module_exit(usb_udc_exit);

MODULE_DESCRIPTION("UDC Framework");
MODULE_AUTHOR("Felipe Balbi <balbi@ti.com>");
MODULE_LICENSE("GPL v2");