/*
 * HWA Host Controller Driver
 * Wire Adapter Control/Data Streaming Iface (WUSB1.0[8])
 *
 * Copyright (C) 2005-2006 Intel Corporation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 *
 * This driver implements a USB Host Controller (struct usb_hcd) for a
 * Wireless USB Host Controller based on the Wireless USB 1.0
 * Host-Wire-Adapter specification (in layman terms, a USB-dongle that
 * implements a Wireless USB host).
 *
 * Check out the Design-overview.txt file in the source documentation
 * for other details on the implementation.
 *
 * Main blocks:
 *
 *  driver     glue with the driver API, workqueue daemon
 *
 *  lc         RC instance life cycle management (create, destroy...)
 *
 *  hcd        glue with the USB API Host Controller Interface API.
 *
 *  nep        Notification EndPoint managent: collect notifications
 *             and queue them with the workqueue daemon.
 *
 *             Handle notifications as coming from the NEP. Sends them
 *             off others to their respective modules (eg: connect,
 *             disconnect and reset go to devconnect).
 *
 *  rpipe      Remote Pipe management; rpipe is what we use to write
 *             to an endpoint on a WUSB device that is connected to a
 *             HWA RC.
 *
 *  xfer       Transfer management -- this is all the code that gets a
 *             buffer and pushes it to a device (or viceversa). *
 *
 * Some day a lot of this code will be shared between this driver and
 * the drivers for DWA (xfer, rpipe).
 *
 * All starts at driver.c:hwahc_probe(), when one of this guys is
 * connected. hwahc_disconnect() stops it.
 *
 * During operation, the main driver is devices connecting or
 * disconnecting. They cause the HWA RC to send notifications into
 * nep.c:hwahc_nep_cb() that will dispatch them to
 * notif.c:wa_notif_dispatch(). From there they will fan to cause
 * device connects, disconnects, etc.
 *
 * Note much of the activity is difficult to follow. For example a
 * device connect goes to devconnect, which will cause the "fake" root
 * hub port to show a connect and stop there. Then khubd will notice
 * and call into the rh.c:hwahc_rc_port_reset() code to authenticate
 * the device (and this might require user intervention) and enable
 * the port.
 *
 * We also have a timer workqueue going from devconnect.c that
 * schedules in hwahc_devconnect_create().
 *
 * The rest of the traffic is in the usual entry points of a USB HCD,
 * which are hooked up in driver.c:hwahc_rc_driver, and defined in
 * hcd.c.
 */

#ifndef __HWAHC_INTERNAL_H__
#define __HWAHC_INTERNAL_H__

#include <linux/completion.h>
#include <linux/usb.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/uwb.h>
#include <linux/usb/wusb.h>
#include <linux/usb/wusb-wa.h>

struct wusbhc;
struct wahc;
extern void wa_urb_enqueue_run(struct work_struct *ws);

/**
 * RPipe instance
 *
 * @descr's fields are kept in LE, as we need to send it back and
 * forth.
 *
 * @wa is referenced when set
 *
 * @segs_available is the number of requests segments that still can
 *                 be submitted to the controller without overloading
 *                 it. It is initialized to descr->wRequests when
 *                 aiming.
 *
 * A rpipe supports a max of descr->wRequests at the same time; before
 * submitting seg_lock has to be taken. If segs_avail > 0, then we can
 * submit; if not, we have to queue them.
 */
struct wa_rpipe {
        struct kref refcnt;
        struct usb_rpipe_descriptor descr;
        struct usb_host_endpoint *ep;
        struct wahc *wa;
        spinlock_t seg_lock;
        struct list_head seg_list;
        atomic_t segs_available;
        u8 buffer[1];   /* For reads/writes on USB */
};


/**
 * Instance of a HWA Host Controller
 *
 * Except where a more specific lock/mutex applies or atomic, all
 * fields protected by @mutex.
 *
 * @wa_descr  Can be accessed without locking because it is in
 *            the same area where the device descriptors were
 *            read, so it is guaranteed to exist umodified while
 *            the device exists.
 *
 *            Endianess has been converted to CPU's.
 *
 * @nep_* can be accessed without locking as its processing is
 *        serialized; we submit a NEP URB and it comes to
 *        hwahc_nep_cb(), which won't issue another URB until it is
 *        done processing it.
 *
 * @xfer_list:
 *
 *   List of active transfers to verify existence from a xfer id
 *   gotten from the xfer result message. Can't use urb->list because
 *   it goes by endpoint, and we don't know the endpoint at the time
 *   when we get the xfer result message. We can't really rely on the
 *   pointer (will have to change for 64 bits) as the xfer id is 32 bits.
 *
 * @xfer_delayed_list:   List of transfers that need to be started
 *                       (with a workqueue, because they were
 *                       submitted from an atomic context).
 *
 * FIXME: this needs to be layered up: a wusbhc layer (for sharing
 *        comonalities with WHCI), a wa layer (for sharing
 *        comonalities with DWA-RC).
 */
struct wahc {
        struct usb_device *usb_dev;
        struct usb_interface *usb_iface;

        /* HC to deliver notifications */
        union {
                struct wusbhc *wusb;
                struct dwahc *dwa;
        };

        const struct usb_endpoint_descriptor *dto_epd, *dti_epd;
        const struct usb_wa_descriptor *wa_descr;

        struct urb *nep_urb;            /* Notification EndPoint [lockless] */
        struct edc nep_edc;
        void *nep_buffer;
        size_t nep_buffer_size;

        atomic_t notifs_queued;

        u16 rpipes;
        unsigned long *rpipe_bm;        /* rpipe usage bitmap */
        spinlock_t rpipe_bm_lock;       /* protect rpipe_bm */
        struct mutex rpipe_mutex;       /* assigning resources to endpoints */

        struct urb *dti_urb;            /* URB for reading xfer results */
        struct urb *buf_in_urb;         /* URB for reading data in */
        struct edc dti_edc;             /* DTI error density counter */
        struct wa_xfer_result *xfer_result; /* real size = dti_ep maxpktsize */
        size_t xfer_result_size;

        s32 status;                     /* For reading status */

        struct list_head xfer_list;
        struct list_head xfer_delayed_list;
        spinlock_t xfer_list_lock;
        struct work_struct xfer_work;
        atomic_t xfer_id_count;
};


extern int wa_create(struct wahc *wa, struct usb_interface *iface);
extern void __wa_destroy(struct wahc *wa);
void wa_reset_all(struct wahc *wa);


/* Miscellaneous constants */
enum {
        /** Max number of EPROTO errors we tolerate on the NEP in a
         * period of time */
        HWAHC_EPROTO_MAX = 16,
        /** Period of time for EPROTO errors (in jiffies) */
        HWAHC_EPROTO_PERIOD = 4 * HZ,
};


/* Notification endpoint handling */
extern int wa_nep_create(struct wahc *, struct usb_interface *);
extern void wa_nep_destroy(struct wahc *);

static inline int wa_nep_arm(struct wahc *wa, gfp_t gfp_mask)
{
        struct urb *urb = wa->nep_urb;
        urb->transfer_buffer = wa->nep_buffer;
        urb->transfer_buffer_length = wa->nep_buffer_size;
        return usb_submit_urb(urb, gfp_mask);
}

static inline void wa_nep_disarm(struct wahc *wa)
{
        usb_kill_urb(wa->nep_urb);
}


/* RPipes */
static inline void wa_rpipe_init(struct wahc *wa)
{
        spin_lock_init(&wa->rpipe_bm_lock);
        mutex_init(&wa->rpipe_mutex);
}

static inline void wa_init(struct wahc *wa)
{
        edc_init(&wa->nep_edc);
        atomic_set(&wa->notifs_queued, 0);
        wa_rpipe_init(wa);
        edc_init(&wa->dti_edc);
        INIT_LIST_HEAD(&wa->xfer_list);
        INIT_LIST_HEAD(&wa->xfer_delayed_list);
        spin_lock_init(&wa->xfer_list_lock);
        INIT_WORK(&wa->xfer_work, wa_urb_enqueue_run);
        atomic_set(&wa->xfer_id_count, 1);
}

/**
 * Destroy a pipe (when refcount drops to zero)
 *
 * Assumes it has been moved to the "QUIESCING" state.
 */
struct wa_xfer;
extern void rpipe_destroy(struct kref *_rpipe);
static inline
void __rpipe_get(struct wa_rpipe *rpipe)
{
        kref_get(&rpipe->refcnt);
}
extern int rpipe_get_by_ep(struct wahc *, struct usb_host_endpoint *,
                           struct urb *, gfp_t);
static inline void rpipe_put(struct wa_rpipe *rpipe)
{
        kref_put(&rpipe->refcnt, rpipe_destroy);

}
extern void rpipe_ep_disable(struct wahc *, struct usb_host_endpoint *);
extern int wa_rpipes_create(struct wahc *);
extern void wa_rpipes_destroy(struct wahc *);
static inline void rpipe_avail_dec(struct wa_rpipe *rpipe)
{
        atomic_dec(&rpipe->segs_available);
}

/**
 * Returns true if the rpipe is ready to submit more segments.
 */
static inline int rpipe_avail_inc(struct wa_rpipe *rpipe)
{
        return atomic_inc_return(&rpipe->segs_available) > 0
                && !list_empty(&rpipe->seg_list);
}


/* Transferring data */
extern int wa_urb_enqueue(struct wahc *, struct usb_host_endpoint *,
                          struct urb *, gfp_t);
extern int wa_urb_dequeue(struct wahc *, struct urb *);
extern void wa_handle_notif_xfer(struct wahc *, struct wa_notif_hdr *);


/* Misc
 *
 * FIXME: Refcounting for the actual @hwahc object is not correct; I
 *        mean, this should be refcounting on the HCD underneath, but
 *        it is not. In any case, the semantics for HCD refcounting
 *        are *weird*...on refcount reaching zero it just frees
 *        it...no RC specific function is called...unless I miss
 *        something.
 *
 * FIXME: has to go away in favour of an 'struct' hcd based sollution
 */
static inline struct wahc *wa_get(struct wahc *wa)
{
        usb_get_intf(wa->usb_iface);
        return wa;
}

static inline void wa_put(struct wahc *wa)
{
        usb_put_intf(wa->usb_iface);
}


static inline int __wa_feature(struct wahc *wa, unsigned op, u16 feature)
{
        return usb_control_msg(wa->usb_dev, usb_sndctrlpipe(wa->usb_dev, 0),
                        op ? USB_REQ_SET_FEATURE : USB_REQ_CLEAR_FEATURE,
                        USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                        feature,
                        wa->usb_iface->cur_altsetting->desc.bInterfaceNumber,
                        NULL, 0, 1000 /* FIXME: arbitrary */);
}


static inline int __wa_set_feature(struct wahc *wa, u16 feature)
{
        return  __wa_feature(wa, 1, feature);
}


static inline int __wa_clear_feature(struct wahc *wa, u16 feature)
{
        return __wa_feature(wa, 0, feature);
}


/**
 * Return the status of a Wire Adapter
 *
 * @wa:         Wire Adapter instance
 * @returns     < 0 errno code on error, or status bitmap as described
 *              in WUSB1.0[8.3.1.6].
 *
 * NOTE: need malloc, some arches don't take USB from the stack
 */
static inline
s32 __wa_get_status(struct wahc *wa)
{
        s32 result;
        result = usb_control_msg(
                wa->usb_dev, usb_rcvctrlpipe(wa->usb_dev, 0),
                USB_REQ_GET_STATUS,
                USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
                0, wa->usb_iface->cur_altsetting->desc.bInterfaceNumber,
                &wa->status, sizeof(wa->status),
                1000 /* FIXME: arbitrary */);
        if (result >= 0)
                result = wa->status;
        return result;
}


/**
 * Waits until the Wire Adapter's status matches @mask/@value
 *
 * @wa:         Wire Adapter instance.
 * @returns     < 0 errno code on error, otherwise status.
 *
 * Loop until the WAs status matches the mask and value (status & mask
 * == value). Timeout if it doesn't happen.
 *
 * FIXME: is there an official specification on how long status
 *        changes can take?
 */
static inline s32 __wa_wait_status(struct wahc *wa, u32 mask, u32 value)
{
        s32 result;
        unsigned loops = 10;
        do {
                msleep(50);
                result = __wa_get_status(wa);
                if ((result & mask) == value)
                        break;
                if (loops-- == 0) {
                        result = -ETIMEDOUT;
                        break;
                }
        } while (result >= 0);
        return result;
}


/** Command @hwahc to stop, @returns 0 if ok, < 0 errno code on error */
static inline int __wa_stop(struct wahc *wa)
{
        int result;
        struct device *dev = &wa->usb_iface->dev;

        result = __wa_clear_feature(wa, WA_ENABLE);
        if (result < 0 && result != -ENODEV) {
                dev_err(dev, "error commanding HC to stop: %d\n", result);
                goto out;
        }
        result = __wa_wait_status(wa, WA_ENABLE, 0);
        if (result < 0 && result != -ENODEV)
                dev_err(dev, "error waiting for HC to stop: %d\n", result);
out:
        return 0;
}


#endif /* #ifndef __HWAHC_INTERNAL_H__ */