/*
 * Ultra Wide Band Radio Control
 * Event Size Tables management
 *
 * 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.
 *
 *
 * FIXME: docs
 *
 * Infrastructure, code and data tables for guessing the size of
 * events received on the notification endpoints of UWB radio
 * controllers.
 *
 * You define a table of events and for each, its size and how to get
 * the extra size.
 *
 * ENTRY POINTS:
 *
 * uwb_est_{init/destroy}(): To initialize/release the EST subsystem.
 *
 * uwb_est_[u]register(): To un/register event size tables
 *   uwb_est_grow()
 *
 * uwb_est_find_size(): Get the size of an event
 *   uwb_est_get_size()
 */
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/export.h>

#include "uwb-internal.h"

struct uwb_est {
        u16 type_event_high;
        u16 vendor, product;
        u8 entries;
        const struct uwb_est_entry *entry;
};

static struct uwb_est *uwb_est;
static u8 uwb_est_size;
static u8 uwb_est_used;
static DEFINE_RWLOCK(uwb_est_lock);

/**
 * WUSB Standard Event Size Table, HWA-RC interface
 *
 * Sizes for events and notifications type 0 (general), high nibble 0.
 */
static
struct uwb_est_entry uwb_est_00_00xx[] = {
        [UWB_RC_EVT_IE_RCV] = {
                .size = sizeof(struct uwb_rc_evt_ie_rcv),
                .offset = 1 + offsetof(struct uwb_rc_evt_ie_rcv, wIELength),
        },
        [UWB_RC_EVT_BEACON] = {
                .size = sizeof(struct uwb_rc_evt_beacon),
                .offset = 1 + offsetof(struct uwb_rc_evt_beacon, wBeaconInfoLength),
        },
        [UWB_RC_EVT_BEACON_SIZE] = {
                .size = sizeof(struct uwb_rc_evt_beacon_size),
        },
        [UWB_RC_EVT_BPOIE_CHANGE] = {
                .size = sizeof(struct uwb_rc_evt_bpoie_change),
                .offset = 1 + offsetof(struct uwb_rc_evt_bpoie_change,
                                       wBPOIELength),
        },
        [UWB_RC_EVT_BP_SLOT_CHANGE] = {
                .size = sizeof(struct uwb_rc_evt_bp_slot_change),
        },
        [UWB_RC_EVT_BP_SWITCH_IE_RCV] = {
                .size = sizeof(struct uwb_rc_evt_bp_switch_ie_rcv),
                .offset = 1 + offsetof(struct uwb_rc_evt_bp_switch_ie_rcv, wIELength),
        },
        [UWB_RC_EVT_DEV_ADDR_CONFLICT] = {
                .size = sizeof(struct uwb_rc_evt_dev_addr_conflict),
        },
        [UWB_RC_EVT_DRP_AVAIL] = {
                .size = sizeof(struct uwb_rc_evt_drp_avail)
        },
        [UWB_RC_EVT_DRP] = {
                .size = sizeof(struct uwb_rc_evt_drp),
                .offset = 1 + offsetof(struct uwb_rc_evt_drp, ie_length),
        },
        [UWB_RC_EVT_BP_SWITCH_STATUS] = {
                .size = sizeof(struct uwb_rc_evt_bp_switch_status),
        },
        [UWB_RC_EVT_CMD_FRAME_RCV] = {
                .size = sizeof(struct uwb_rc_evt_cmd_frame_rcv),
                .offset = 1 + offsetof(struct uwb_rc_evt_cmd_frame_rcv, dataLength),
        },
        [UWB_RC_EVT_CHANNEL_CHANGE_IE_RCV] = {
                .size = sizeof(struct uwb_rc_evt_channel_change_ie_rcv),
                .offset = 1 + offsetof(struct uwb_rc_evt_channel_change_ie_rcv, wIELength),
        },
        [UWB_RC_CMD_CHANNEL_CHANGE] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_DEV_ADDR_MGMT] = {
                .size = sizeof(struct uwb_rc_evt_dev_addr_mgmt) },
        [UWB_RC_CMD_GET_IE] = {
                .size = sizeof(struct uwb_rc_evt_get_ie),
                .offset = 1 + offsetof(struct uwb_rc_evt_get_ie, wIELength),
        },
        [UWB_RC_CMD_RESET] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_SCAN] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_SET_BEACON_FILTER] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_SET_DRP_IE] = {
                .size = sizeof(struct uwb_rc_evt_set_drp_ie),
        },
        [UWB_RC_CMD_SET_IE] = {
                .size = sizeof(struct uwb_rc_evt_set_ie),
        },
        [UWB_RC_CMD_SET_NOTIFICATION_FILTER] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_SET_TX_POWER] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_SLEEP] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_START_BEACON] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_STOP_BEACON] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_BP_MERGE] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_SEND_COMMAND_FRAME] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
        [UWB_RC_CMD_SET_ASIE_NOTIF] = {
                .size = sizeof(struct uwb_rc_evt_confirm),
        },
};

static
struct uwb_est_entry uwb_est_01_00xx[] = {
        [UWB_RC_DAA_ENERGY_DETECTED] = {
                .size = sizeof(struct uwb_rc_evt_daa_energy_detected),
        },
        [UWB_RC_SET_DAA_ENERGY_MASK] = {
                .size = sizeof(struct uwb_rc_evt_set_daa_energy_mask),
        },
        [UWB_RC_SET_NOTIFICATION_FILTER_EX] = {
                .size = sizeof(struct uwb_rc_evt_set_notification_filter_ex),
        },
};

/**
 * Initialize the EST subsystem
 *
 * Register the standard tables also.
 *
 * FIXME: tag init
 */
int uwb_est_create(void)
{
        int result;

        uwb_est_size = 2;
        uwb_est_used = 0;
        uwb_est = kcalloc(uwb_est_size, sizeof(uwb_est[0]), GFP_KERNEL);
        if (uwb_est == NULL)
                return -ENOMEM;

        result = uwb_est_register(UWB_RC_CET_GENERAL, 0, 0xffff, 0xffff,
                                  uwb_est_00_00xx, ARRAY_SIZE(uwb_est_00_00xx));
        if (result < 0)
                goto out;
        result = uwb_est_register(UWB_RC_CET_EX_TYPE_1, 0, 0xffff, 0xffff,
                                  uwb_est_01_00xx, ARRAY_SIZE(uwb_est_01_00xx));
out:
        return result;
}


/** Clean it up */
void uwb_est_destroy(void)
{
        kfree(uwb_est);
        uwb_est = NULL;
        uwb_est_size = uwb_est_used = 0;
}


/**
 * Double the capacity of the EST table
 *
 * @returns 0 if ok, < 0 errno no error.
 */
static
int uwb_est_grow(void)
{
        size_t actual_size = uwb_est_size * sizeof(uwb_est[0]);
        void *new = kmalloc(2 * actual_size, GFP_ATOMIC);
        if (new == NULL)
                return -ENOMEM;
        memcpy(new, uwb_est, actual_size);
        memset(new + actual_size, 0, actual_size);
        kfree(uwb_est);
        uwb_est = new;
        uwb_est_size *= 2;
        return 0;
}


/**
 * Register an event size table
 *
 * Makes room for it if the table is full, and then inserts  it in the
 * right position (entries are sorted by type, event_high, vendor and
 * then product).
 *
 * @vendor:  vendor code for matching against the device (0x0000 and
 *           0xffff mean any); use 0x0000 to force all to match without
 *           checking possible vendor specific ones, 0xfffff to match
 *           after checking vendor specific ones.
 *
 * @product: product code from that vendor; same matching rules, use
 *           0x0000 for not allowing vendor specific matches, 0xffff
 *           for allowing.
 *
 * This arragement just makes the tables sort differenty. Because the
 * table is sorted by growing type-event_high-vendor-product, a zero
 * vendor will match before than a 0x456a vendor, that will match
 * before a 0xfffff vendor.
 *
 * @returns 0 if ok, < 0 errno on error (-ENOENT if not found).
 */
/* FIXME: add bus type to vendor/product code */
int uwb_est_register(u8 type, u8 event_high, u16 vendor, u16 product,
                     const struct uwb_est_entry *entry, size_t entries)
{
        unsigned long flags;
        unsigned itr;
        int result = 0;

        write_lock_irqsave(&uwb_est_lock, flags);
        if (uwb_est_used == uwb_est_size) {
                result = uwb_est_grow();
                if (result < 0)
                        goto out;
        }
        /* Find the right spot to insert it in */
        for (itr = 0; itr < uwb_est_used; itr++)
                if (uwb_est[itr].type_event_high < type
                    && uwb_est[itr].vendor < vendor
                    && uwb_est[itr].product < product)
                        break;

        /* Shift others to make room for the new one? */
        if (itr < uwb_est_used)
                memmove(&uwb_est[itr+1], &uwb_est[itr], uwb_est_used - itr);
        uwb_est[itr].type_event_high = type << 8 | event_high;
        uwb_est[itr].vendor = vendor;
        uwb_est[itr].product = product;
        uwb_est[itr].entry = entry;
        uwb_est[itr].entries = entries;
        uwb_est_used++;
out:
        write_unlock_irqrestore(&uwb_est_lock, flags);
        return result;
}
EXPORT_SYMBOL_GPL(uwb_est_register);


/**
 * Unregister an event size table
 *
 * This just removes the specified entry and moves the ones after it
 * to fill in the gap. This is needed to keep the list sorted; no
 * reallocation is done to reduce the size of the table.
 *
 * We unregister by all the data we used to register instead of by
 * pointer to the @entry array because we might have used the same
 * table for a bunch of IDs (for example).
 *
 * @returns 0 if ok, < 0 errno on error (-ENOENT if not found).
 */
int uwb_est_unregister(u8 type, u8 event_high, u16 vendor, u16 product,
                       const struct uwb_est_entry *entry, size_t entries)
{
        unsigned long flags;
        unsigned itr;
        struct uwb_est est_cmp = {
                .type_event_high = type << 8 | event_high,
                .vendor = vendor,
                .product = product,
                .entry = entry,
                .entries = entries
        };
        write_lock_irqsave(&uwb_est_lock, flags);
        for (itr = 0; itr < uwb_est_used; itr++)
                if (!memcmp(&uwb_est[itr], &est_cmp, sizeof(est_cmp)))
                        goto found;
        write_unlock_irqrestore(&uwb_est_lock, flags);
        return -ENOENT;

found:
        if (itr < uwb_est_used - 1)     /* Not last one? move ones above */
                memmove(&uwb_est[itr], &uwb_est[itr+1], uwb_est_used - itr - 1);
        uwb_est_used--;
        write_unlock_irqrestore(&uwb_est_lock, flags);
        return 0;
}
EXPORT_SYMBOL_GPL(uwb_est_unregister);


/**
 * Get the size of an event from a table
 *
 * @rceb: pointer to the buffer with the event
 * @rceb_size: size of the area pointed to by @rceb in bytes.
 * @returns: > 0      Size of the event
 *           -ENOSPC  An area big enough was not provided to look
 *                    ahead into the event's guts and guess the size.
 *           -EINVAL  Unknown event code (wEvent).
 *
 * This will look at the received RCEB and guess what is the total
 * size. For variable sized events, it will look further ahead into
 * their length field to see how much data should be read.
 *
 * Note this size is *not* final--the neh (Notification/Event Handle)
 * might specificy an extra size to add.
 */
static
ssize_t uwb_est_get_size(struct uwb_rc *uwb_rc, struct uwb_est *est,
                         u8 event_low, const struct uwb_rceb *rceb,
                         size_t rceb_size)
{
        unsigned offset;
        ssize_t size;
        struct device *dev = &uwb_rc->uwb_dev.dev;
        const struct uwb_est_entry *entry;

        size = -ENOENT;
        if (event_low >= est->entries) {        /* in range? */
                dev_err(dev, "EST %p 0x%04x/%04x/%04x[%u]: event %u out of range\n",
                        est, est->type_event_high, est->vendor, est->product,
                        est->entries, event_low);
                goto out;
        }
        size = -ENOENT;
        entry = &est->entry[event_low];
        if (entry->size == 0 && entry->offset == 0) {   /* unknown? */
                dev_err(dev, "EST %p 0x%04x/%04x/%04x[%u]: event %u unknown\n",
                        est, est->type_event_high, est->vendor, est->product,
                        est->entries, event_low);
                goto out;
        }
        offset = entry->offset; /* extra fries with that? */
        if (offset == 0)
                size = entry->size;
        else {
                /* Ops, got an extra size field at 'offset'--read it */
                const void *ptr = rceb;
                size_t type_size = 0;
                offset--;
                size = -ENOSPC;                 /* enough data for more? */
                switch (entry->type) {
                case UWB_EST_16:  type_size = sizeof(__le16); break;
                case UWB_EST_8:   type_size = sizeof(u8);     break;
                default:         BUG();
                }
                if (offset + type_size > rceb_size) {
                        dev_err(dev, "EST %p 0x%04x/%04x/%04x[%u]: "
                                "not enough data to read extra size\n",
                                est, est->type_event_high, est->vendor,
                                est->product, est->entries);
                        goto out;
                }
                size = entry->size;
                ptr += offset;
                switch (entry->type) {
                case UWB_EST_16:  size += le16_to_cpu(*(__le16 *)ptr); break;
                case UWB_EST_8:   size += *(u8 *)ptr;                  break;
                default:         BUG();
                }
        }
out:
        return size;
}


/**
 * Guesses the size of a WA event
 *
 * @rceb: pointer to the buffer with the event
 * @rceb_size: size of the area pointed to by @rceb in bytes.
 * @returns: > 0      Size of the event
 *           -ENOSPC  An area big enough was not provided to look
 *                    ahead into the event's guts and guess the size.
 *           -EINVAL  Unknown event code (wEvent).
 *
 * This will look at the received RCEB and guess what is the total
 * size by checking all the tables registered with
 * uwb_est_register(). For variable sized events, it will look further
 * ahead into their length field to see how much data should be read.
 *
 * Note this size is *not* final--the neh (Notification/Event Handle)
 * might specificy an extra size to add or replace.
 */
ssize_t uwb_est_find_size(struct uwb_rc *rc, const struct uwb_rceb *rceb,
                          size_t rceb_size)
{
        /* FIXME: add vendor/product data */
        ssize_t size;
        struct device *dev = &rc->uwb_dev.dev;
        unsigned long flags;
        unsigned itr;
        u16 type_event_high, event;

        read_lock_irqsave(&uwb_est_lock, flags);
        size = -ENOSPC;
        if (rceb_size < sizeof(*rceb))
                goto out;
        event = le16_to_cpu(rceb->wEvent);
        type_event_high = rceb->bEventType << 8 | (event & 0xff00) >> 8;
        for (itr = 0; itr < uwb_est_used; itr++) {
                if (uwb_est[itr].type_event_high != type_event_high)
                        continue;
                size = uwb_est_get_size(rc, &uwb_est[itr],
                                        event & 0x00ff, rceb, rceb_size);
                /* try more tables that might handle the same type */
                if (size != -ENOENT)
                        goto out;
        }
        dev_dbg(dev,
                "event 0x%02x/%04x/%02x: no handlers available; RCEB %4ph\n",
                (unsigned) rceb->bEventType,
                (unsigned) le16_to_cpu(rceb->wEvent),
                (unsigned) rceb->bEventContext,
                rceb);
        size = -ENOENT;
out:
        read_unlock_irqrestore(&uwb_est_lock, flags);
        return size;
}
EXPORT_SYMBOL_GPL(uwb_est_find_size);