hci_ll.c

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/*
 *  Texas Instruments' Bluetooth HCILL UART protocol
 *
 *  HCILL (HCI Low Level) is a Texas Instruments' power management
 *  protocol extension to H4.
 *
 *  Copyright (C) 2007 Texas Instruments, Inc.
 *
 *  Written by Ohad Ben-Cohen <[email protected]>
 *
 *  Acknowledgements:
 *  This file is based on hci_h4.c, which was written
 *  by Maxim Krasnyansky and Marcel Holtmann.
 *
 *  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>

#include <linux/init.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/poll.h>

#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/signal.h>
#include <linux/ioctl.h>
#include <linux/skbuff.h>

#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>

#include "hci_uart.h"

/* HCILL commands */
#define HCILL_GO_TO_SLEEP_IND   0x30
#define HCILL_GO_TO_SLEEP_ACK   0x31
#define HCILL_WAKE_UP_IND   0x32
#define HCILL_WAKE_UP_ACK   0x33

/* HCILL receiver States */
#define HCILL_W4_PACKET_TYPE    0
#define HCILL_W4_EVENT_HDR  1
#define HCILL_W4_ACL_HDR    2
#define HCILL_W4_SCO_HDR    3
#define HCILL_W4_DATA       4

/* HCILL states */
enum hcill_states_e {
    HCILL_ASLEEP,
    HCILL_ASLEEP_TO_AWAKE,
    HCILL_AWAKE,
    HCILL_AWAKE_TO_ASLEEP
};

struct hcill_cmd {
    u8 cmd;
} __packed;

struct ll_struct {
    unsigned long rx_state;
    unsigned long rx_count;
    struct sk_buff *rx_skb;
    struct sk_buff_head txq;
    spinlock_t hcill_lock;      /* HCILL state lock */
    unsigned long hcill_state;  /* HCILL power state    */
    struct sk_buff_head tx_wait_q;  /* HCILL wait queue */
};

/*
 * Builds and sends an HCILL command packet.
 * These are very simple packets with only 1 cmd byte
 */
static int send_hcill_cmd(u8 cmd, struct hci_uart *hu)
{
    int err = 0;
    struct sk_buff *skb = NULL;
    struct ll_struct *ll = hu->priv;
    struct hcill_cmd *hcill_packet;

    BT_DBG("hu %p cmd 0x%x", hu, cmd);

    /* allocate packet */
    skb = bt_skb_alloc(1, GFP_ATOMIC);
    if (!skb) {
        BT_ERR("cannot allocate memory for HCILL packet");
        err = -ENOMEM;
        goto out;
    }

    /* prepare packet */
    hcill_packet = (struct hcill_cmd *) skb_put(skb, 1);
    hcill_packet->cmd = cmd;
    skb->dev = (void *) hu->hdev;

    /* send packet */
    skb_queue_tail(&ll->txq, skb);
out:
    return err;
}

/* Initialize protocol */
static int ll_open(struct hci_uart *hu)
{
    struct ll_struct *ll;

    BT_DBG("hu %p", hu);

    ll = kzalloc(sizeof(*ll), GFP_KERNEL);
    if (!ll)
        return -ENOMEM;

    skb_queue_head_init(&ll->txq);
    skb_queue_head_init(&ll->tx_wait_q);
    spin_lock_init(&ll->hcill_lock);

    ll->hcill_state = HCILL_AWAKE;

    hu->priv = ll;

    return 0;
}

/* Flush protocol data */
static int ll_flush(struct hci_uart *hu)
{
    struct ll_struct *ll = hu->priv;

    BT_DBG("hu %p", hu);

    skb_queue_purge(&ll->tx_wait_q);
    skb_queue_purge(&ll->txq);

    return 0;
}

/* Close protocol */
static int ll_close(struct hci_uart *hu)
{
    struct ll_struct *ll = hu->priv;

    BT_DBG("hu %p", hu);

    skb_queue_purge(&ll->tx_wait_q);
    skb_queue_purge(&ll->txq);

    kfree_skb(ll->rx_skb);

    hu->priv = NULL;

    kfree(ll);

    return 0;
}

/*
 * internal function, which does common work of the device wake up process:
 * 1. places all pending packets (waiting in tx_wait_q list) in txq list.
 * 2. changes internal state to HCILL_AWAKE.
 * Note: assumes that hcill_lock spinlock is taken,
 * shouldn't be called otherwise!
 */
static void __ll_do_awake(struct ll_struct *ll)
{
    struct sk_buff *skb = NULL;

    while ((skb = skb_dequeue(&ll->tx_wait_q)))
        skb_queue_tail(&ll->txq, skb);

    ll->hcill_state = HCILL_AWAKE;
}

/*
 * Called upon a wake-up-indication from the device
 */
static void ll_device_want_to_wakeup(struct hci_uart *hu)
{
    unsigned long flags;
    struct ll_struct *ll = hu->priv;

    BT_DBG("hu %p", hu);

    /* lock hcill state */
    spin_lock_irqsave(&ll->hcill_lock, flags);

    switch (ll->hcill_state) {
    case HCILL_ASLEEP_TO_AWAKE:
        /*
         * This state means that both the host and the BRF chip
         * have simultaneously sent a wake-up-indication packet.
         * Traditionally, in this case, receiving a wake-up-indication
         * was enough and an additional wake-up-ack wasn't needed.
         * This has changed with the BRF6350, which does require an
         * explicit wake-up-ack. Other BRF versions, which do not
         * require an explicit ack here, do accept it, thus it is
         * perfectly safe to always send one.
         */
        BT_DBG("dual wake-up-indication");
        /* deliberate fall-through - do not add break */
    case HCILL_ASLEEP:
        /* acknowledge device wake up */
        if (send_hcill_cmd(HCILL_WAKE_UP_ACK, hu) < 0) {
            BT_ERR("cannot acknowledge device wake up");
            goto out;
        }
        break;
    default:
        /* any other state is illegal */
        BT_ERR("received HCILL_WAKE_UP_IND in state %ld", ll->hcill_state);
        break;
    }

    /* send pending packets and change state to HCILL_AWAKE */
    __ll_do_awake(ll);

out:
    spin_unlock_irqrestore(&ll->hcill_lock, flags);

    /* actually send the packets */
    hci_uart_tx_wakeup(hu);
}

/*
 * Called upon a sleep-indication from the device
 */
static void ll_device_want_to_sleep(struct hci_uart *hu)
{
    unsigned long flags;
    struct ll_struct *ll = hu->priv;

    BT_DBG("hu %p", hu);

    /* lock hcill state */
    spin_lock_irqsave(&ll->hcill_lock, flags);

    /* sanity check */
    if (ll->hcill_state != HCILL_AWAKE)
        BT_ERR("ERR: HCILL_GO_TO_SLEEP_IND in state %ld", ll->hcill_state);

    /* acknowledge device sleep */
    if (send_hcill_cmd(HCILL_GO_TO_SLEEP_ACK, hu) < 0) {
        BT_ERR("cannot acknowledge device sleep");
        goto out;
    }

    /* update state */
    ll->hcill_state = HCILL_ASLEEP;

out:
    spin_unlock_irqrestore(&ll->hcill_lock, flags);

    /* actually send the sleep ack packet */
    hci_uart_tx_wakeup(hu);
}

/*
 * Called upon wake-up-acknowledgement from the device
 */
static void ll_device_woke_up(struct hci_uart *hu)
{
    unsigned long flags;
    struct ll_struct *ll = hu->priv;

    BT_DBG("hu %p", hu);

    /* lock hcill state */
    spin_lock_irqsave(&ll->hcill_lock, flags);

    /* sanity check */
    if (ll->hcill_state != HCILL_ASLEEP_TO_AWAKE)
        BT_ERR("received HCILL_WAKE_UP_ACK in state %ld", ll->hcill_state);

    /* send pending packets and change state to HCILL_AWAKE */
    __ll_do_awake(ll);

    spin_unlock_irqrestore(&ll->hcill_lock, flags);

    /* actually send the packets */
    hci_uart_tx_wakeup(hu);
}

/* Enqueue frame for transmittion (padding, crc, etc) */
/* may be called from two simultaneous tasklets */
static int ll_enqueue(struct hci_uart *hu, struct sk_buff *skb)
{
    unsigned long flags = 0;
    struct ll_struct *ll = hu->priv;

    BT_DBG("hu %p skb %p", hu, skb);

    /* Prepend skb with frame type */
    memcpy(skb_push(skb, 1), &bt_cb(skb)->pkt_type, 1);

    /* lock hcill state */
    spin_lock_irqsave(&ll->hcill_lock, flags);

    /* act according to current state */
    switch (ll->hcill_state) {
    case HCILL_AWAKE:
        BT_DBG("device awake, sending normally");
        skb_queue_tail(&ll->txq, skb);
        break;
    case HCILL_ASLEEP:
        BT_DBG("device asleep, waking up and queueing packet");
        /* save packet for later */
        skb_queue_tail(&ll->tx_wait_q, skb);
        /* awake device */
        if (send_hcill_cmd(HCILL_WAKE_UP_IND, hu) < 0) {
            BT_ERR("cannot wake up device");
            break;
        }
        ll->hcill_state = HCILL_ASLEEP_TO_AWAKE;
        break;
    case HCILL_ASLEEP_TO_AWAKE:
        BT_DBG("device waking up, queueing packet");
        /* transient state; just keep packet for later */
        skb_queue_tail(&ll->tx_wait_q, skb);
        break;
    default:
        BT_ERR("illegal hcill state: %ld (losing packet)", ll->hcill_state);
        kfree_skb(skb);
        break;
    }

    spin_unlock_irqrestore(&ll->hcill_lock, flags);

    return 0;
}

static inline int ll_check_data_len(struct ll_struct *ll, int len)
{
    int room = skb_tailroom(ll->rx_skb);

    BT_DBG("len %d room %d", len, room);

    if (!len) {
        hci_recv_frame(ll->rx_skb);
    } else if (len > room) {
        BT_ERR("Data length is too large");
        kfree_skb(ll->rx_skb);
    } else {
        ll->rx_state = HCILL_W4_DATA;
        ll->rx_count = len;
        return len;
    }

    ll->rx_state = HCILL_W4_PACKET_TYPE;
    ll->rx_skb   = NULL;
    ll->rx_count = 0;

    return 0;
}

/* Recv data */
static int ll_recv(struct hci_uart *hu, void *data, int count)
{
    struct ll_struct *ll = hu->priv;
    char *ptr;
    struct hci_event_hdr *eh;
    struct hci_acl_hdr   *ah;
    struct hci_sco_hdr   *sh;
    int len, type, dlen;

    BT_DBG("hu %p count %d rx_state %ld rx_count %ld", hu, count, ll->rx_state, ll->rx_count);

    ptr = data;
    while (count) {
        if (ll->rx_count) {
            len = min_t(unsigned int, ll->rx_count, count);
            memcpy(skb_put(ll->rx_skb, len), ptr, len);
            ll->rx_count -= len; count -= len; ptr += len;

            if (ll->rx_count)
                continue;

            switch (ll->rx_state) {
            case HCILL_W4_DATA:
                BT_DBG("Complete data");
                hci_recv_frame(ll->rx_skb);

                ll->rx_state = HCILL_W4_PACKET_TYPE;
                ll->rx_skb = NULL;
                continue;

            case HCILL_W4_EVENT_HDR:
                eh = hci_event_hdr(ll->rx_skb);

                BT_DBG("Event header: evt 0x%2.2x plen %d", eh->evt, eh->plen);

                ll_check_data_len(ll, eh->plen);
                continue;

            case HCILL_W4_ACL_HDR:
                ah = hci_acl_hdr(ll->rx_skb);
                dlen = __le16_to_cpu(ah->dlen);

                BT_DBG("ACL header: dlen %d", dlen);

                ll_check_data_len(ll, dlen);
                continue;

            case HCILL_W4_SCO_HDR:
                sh = hci_sco_hdr(ll->rx_skb);

                BT_DBG("SCO header: dlen %d", sh->dlen);

                ll_check_data_len(ll, sh->dlen);
                continue;
            }
        }

        /* HCILL_W4_PACKET_TYPE */
        switch (*ptr) {
        case HCI_EVENT_PKT:
            BT_DBG("Event packet");
            ll->rx_state = HCILL_W4_EVENT_HDR;
            ll->rx_count = HCI_EVENT_HDR_SIZE;
            type = HCI_EVENT_PKT;
            break;

        case HCI_ACLDATA_PKT:
            BT_DBG("ACL packet");
            ll->rx_state = HCILL_W4_ACL_HDR;
            ll->rx_count = HCI_ACL_HDR_SIZE;
            type = HCI_ACLDATA_PKT;
            break;

        case HCI_SCODATA_PKT:
            BT_DBG("SCO packet");
            ll->rx_state = HCILL_W4_SCO_HDR;
            ll->rx_count = HCI_SCO_HDR_SIZE;
            type = HCI_SCODATA_PKT;
            break;

        /* HCILL signals */
        case HCILL_GO_TO_SLEEP_IND:
            BT_DBG("HCILL_GO_TO_SLEEP_IND packet");
            ll_device_want_to_sleep(hu);
            ptr++; count--;
            continue;

        case HCILL_GO_TO_SLEEP_ACK:
            /* shouldn't happen */
            BT_ERR("received HCILL_GO_TO_SLEEP_ACK (in state %ld)", ll->hcill_state);
            ptr++; count--;
            continue;

        case HCILL_WAKE_UP_IND:
            BT_DBG("HCILL_WAKE_UP_IND packet");
            ll_device_want_to_wakeup(hu);
            ptr++; count--;
            continue;

        case HCILL_WAKE_UP_ACK:
            BT_DBG("HCILL_WAKE_UP_ACK packet");
            ll_device_woke_up(hu);
            ptr++; count--;
            continue;

        default:
            BT_ERR("Unknown HCI packet type %2.2x", (__u8)*ptr);
            hu->hdev->stat.err_rx++;
            ptr++; count--;
            continue;
        }

        ptr++; count--;

        /* Allocate packet */
        ll->rx_skb = bt_skb_alloc(HCI_MAX_FRAME_SIZE, GFP_ATOMIC);
        if (!ll->rx_skb) {
            BT_ERR("Can't allocate mem for new packet");
            ll->rx_state = HCILL_W4_PACKET_TYPE;
            ll->rx_count = 0;
            return -ENOMEM;
        }

        ll->rx_skb->dev = (void *) hu->hdev;
        bt_cb(ll->rx_skb)->pkt_type = type;
    }

    return count;
}

static struct sk_buff *ll_dequeue(struct hci_uart *hu)
{
    struct ll_struct *ll = hu->priv;
    return skb_dequeue(&ll->txq);
}

static struct hci_uart_proto llp = {
    .id     = HCI_UART_LL,
    .open       = ll_open,
    .close      = ll_close,
    .recv       = ll_recv,
    .enqueue    = ll_enqueue,
    .dequeue    = ll_dequeue,
    .flush      = ll_flush,
};

int __init ll_init(void)
{
    int err = hci_uart_register_proto(&llp);

    if (!err)
        BT_INFO("HCILL protocol initialized");
    else
        BT_ERR("HCILL protocol registration failed");

    return err;
}

int __exit ll_deinit(void)
{
    return hci_uart_unregister_proto(&llp);
}