UBUNTU: Ubuntu-raspi2-4.10.0-1002.4

[mirror_ubuntu-zesty-kernel.git] / drivers / bluetooth / hci_h5.c

/*
 *
 *  Bluetooth HCI Three-wire UART driver
 *
 *  Copyright (C) 2012  Intel Corporation
 *
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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/kernel.h>
#include <linux/errno.h>
#include <linux/skbuff.h>

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

#include "hci_uart.h"

#define HCI_3WIRE_ACK_PKT       0
#define HCI_3WIRE_LINK_PKT      15

/* Sliding window size */
#define H5_TX_WIN_MAX           4

#define H5_ACK_TIMEOUT  msecs_to_jiffies(250)
#define H5_SYNC_TIMEOUT msecs_to_jiffies(100)

/*
 * Maximum Three-wire packet:
 *     4 byte header + max value for 12-bit length + 2 bytes for CRC
 */
#define H5_MAX_LEN (4 + 0xfff + 2)

/* Convenience macros for reading Three-wire header values */
#define H5_HDR_SEQ(hdr)         ((hdr)[0] & 0x07)
#define H5_HDR_ACK(hdr)         (((hdr)[0] >> 3) & 0x07)
#define H5_HDR_CRC(hdr)         (((hdr)[0] >> 6) & 0x01)
#define H5_HDR_RELIABLE(hdr)    (((hdr)[0] >> 7) & 0x01)
#define H5_HDR_PKT_TYPE(hdr)    ((hdr)[1] & 0x0f)
#define H5_HDR_LEN(hdr)         ((((hdr)[1] >> 4) & 0x0f) + ((hdr)[2] << 4))

#define SLIP_DELIMITER  0xc0
#define SLIP_ESC        0xdb
#define SLIP_ESC_DELIM  0xdc
#define SLIP_ESC_ESC    0xdd

/* H5 state flags */
enum {
        H5_RX_ESC,      /* SLIP escape mode */
        H5_TX_ACK_REQ,  /* Pending ack to send */
};

struct h5 {
        struct sk_buff_head     unack;          /* Unack'ed packets queue */
        struct sk_buff_head     rel;            /* Reliable packets queue */
        struct sk_buff_head     unrel;          /* Unreliable packets queue */

        unsigned long           flags;

        struct sk_buff          *rx_skb;        /* Receive buffer */
        size_t                  rx_pending;     /* Expecting more bytes */
        u8                      rx_ack;         /* Last ack number received */

        int                     (*rx_func)(struct hci_uart *hu, u8 c);

        struct timer_list       timer;          /* Retransmission timer */

        u8                      tx_seq;         /* Next seq number to send */
        u8                      tx_ack;         /* Next ack number to send */
        u8                      tx_win;         /* Sliding window size */

        enum {
                H5_UNINITIALIZED,
                H5_INITIALIZED,
                H5_ACTIVE,
        } state;

        enum {
                H5_AWAKE,
                H5_SLEEPING,
                H5_WAKING_UP,
        } sleep;
};

static void h5_reset_rx(struct h5 *h5);

static void h5_link_control(struct hci_uart *hu, const void *data, size_t len)
{
        struct h5 *h5 = hu->priv;
        struct sk_buff *nskb;

        nskb = alloc_skb(3, GFP_ATOMIC);
        if (!nskb)
                return;

        hci_skb_pkt_type(nskb) = HCI_3WIRE_LINK_PKT;

        memcpy(skb_put(nskb, len), data, len);

        skb_queue_tail(&h5->unrel, nskb);
}

static u8 h5_cfg_field(struct h5 *h5)
{
        /* Sliding window size (first 3 bits) */
        return h5->tx_win & 0x07;
}

static void h5_timed_event(unsigned long arg)
{
        const unsigned char sync_req[] = { 0x01, 0x7e };
        unsigned char conf_req[3] = { 0x03, 0xfc };
        struct hci_uart *hu = (struct hci_uart *)arg;
        struct h5 *h5 = hu->priv;
        struct sk_buff *skb;
        unsigned long flags;

        BT_DBG("%s", hu->hdev->name);

        if (h5->state == H5_UNINITIALIZED)
                h5_link_control(hu, sync_req, sizeof(sync_req));

        if (h5->state == H5_INITIALIZED) {
                conf_req[2] = h5_cfg_field(h5);
                h5_link_control(hu, conf_req, sizeof(conf_req));
        }

        if (h5->state != H5_ACTIVE) {
                mod_timer(&h5->timer, jiffies + H5_SYNC_TIMEOUT);
                goto wakeup;
        }

        if (h5->sleep != H5_AWAKE) {
                h5->sleep = H5_SLEEPING;
                goto wakeup;
        }

        BT_DBG("hu %p retransmitting %u pkts", hu, h5->unack.qlen);

        spin_lock_irqsave_nested(&h5->unack.lock, flags, SINGLE_DEPTH_NESTING);

        while ((skb = __skb_dequeue_tail(&h5->unack)) != NULL) {
                h5->tx_seq = (h5->tx_seq - 1) & 0x07;
                skb_queue_head(&h5->rel, skb);
        }

        spin_unlock_irqrestore(&h5->unack.lock, flags);

wakeup:
        hci_uart_tx_wakeup(hu);
}

static void h5_peer_reset(struct hci_uart *hu)
{
        struct h5 *h5 = hu->priv;

        BT_ERR("Peer device has reset");

        h5->state = H5_UNINITIALIZED;

        del_timer(&h5->timer);

        skb_queue_purge(&h5->rel);
        skb_queue_purge(&h5->unrel);
        skb_queue_purge(&h5->unack);

        h5->tx_seq = 0;
        h5->tx_ack = 0;

        /* Send reset request to upper stack */
        hci_reset_dev(hu->hdev);
}

static int h5_open(struct hci_uart *hu)
{
        struct h5 *h5;
        const unsigned char sync[] = { 0x01, 0x7e };

        BT_DBG("hu %p", hu);

        h5 = kzalloc(sizeof(*h5), GFP_KERNEL);
        if (!h5)
                return -ENOMEM;

        hu->priv = h5;

        skb_queue_head_init(&h5->unack);
        skb_queue_head_init(&h5->rel);
        skb_queue_head_init(&h5->unrel);

        h5_reset_rx(h5);

        setup_timer(&h5->timer, h5_timed_event, (unsigned long)hu);

        h5->tx_win = H5_TX_WIN_MAX;

        set_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags);

        /* Send initial sync request */
        h5_link_control(hu, sync, sizeof(sync));
        mod_timer(&h5->timer, jiffies + H5_SYNC_TIMEOUT);

        return 0;
}

static int h5_close(struct hci_uart *hu)
{
        struct h5 *h5 = hu->priv;

        del_timer_sync(&h5->timer);

        skb_queue_purge(&h5->unack);
        skb_queue_purge(&h5->rel);
        skb_queue_purge(&h5->unrel);

        kfree(h5);

        return 0;
}

static void h5_pkt_cull(struct h5 *h5)
{
        struct sk_buff *skb, *tmp;
        unsigned long flags;
        int i, to_remove;
        u8 seq;

        spin_lock_irqsave(&h5->unack.lock, flags);

        to_remove = skb_queue_len(&h5->unack);
        if (to_remove == 0)
                goto unlock;

        seq = h5->tx_seq;

        while (to_remove > 0) {
                if (h5->rx_ack == seq)
                        break;

                to_remove--;
                seq = (seq - 1) & 0x07;
        }

        if (seq != h5->rx_ack)
                BT_ERR("Controller acked invalid packet");

        i = 0;
        skb_queue_walk_safe(&h5->unack, skb, tmp) {
                if (i++ >= to_remove)
                        break;

                __skb_unlink(skb, &h5->unack);
                kfree_skb(skb);
        }

        if (skb_queue_empty(&h5->unack))
                del_timer(&h5->timer);

unlock:
        spin_unlock_irqrestore(&h5->unack.lock, flags);
}

static void h5_handle_internal_rx(struct hci_uart *hu)
{
        struct h5 *h5 = hu->priv;
        const unsigned char sync_req[] = { 0x01, 0x7e };
        const unsigned char sync_rsp[] = { 0x02, 0x7d };
        unsigned char conf_req[3] = { 0x03, 0xfc };
        const unsigned char conf_rsp[] = { 0x04, 0x7b };
        const unsigned char wakeup_req[] = { 0x05, 0xfa };
        const unsigned char woken_req[] = { 0x06, 0xf9 };
        const unsigned char sleep_req[] = { 0x07, 0x78 };
        const unsigned char *hdr = h5->rx_skb->data;
        const unsigned char *data = &h5->rx_skb->data[4];

        BT_DBG("%s", hu->hdev->name);

        if (H5_HDR_PKT_TYPE(hdr) != HCI_3WIRE_LINK_PKT)
                return;

        if (H5_HDR_LEN(hdr) < 2)
                return;

        conf_req[2] = h5_cfg_field(h5);

        if (memcmp(data, sync_req, 2) == 0) {
                if (h5->state == H5_ACTIVE)
                        h5_peer_reset(hu);
                h5_link_control(hu, sync_rsp, 2);
        } else if (memcmp(data, sync_rsp, 2) == 0) {
                if (h5->state == H5_ACTIVE)
                        h5_peer_reset(hu);
                h5->state = H5_INITIALIZED;
                h5_link_control(hu, conf_req, 3);
        } else if (memcmp(data, conf_req, 2) == 0) {
                h5_link_control(hu, conf_rsp, 2);
                if (h5->state != H5_ACTIVE)
                    h5_link_control(hu, conf_req, 3);
        } else if (memcmp(data, conf_rsp, 2) == 0) {
                if (H5_HDR_LEN(hdr) > 2)
                        h5->tx_win = (data[2] & 0x07);
                BT_DBG("Three-wire init complete. tx_win %u", h5->tx_win);
                h5->state = H5_ACTIVE;
                hci_uart_init_ready(hu);
                return;
        } else if (memcmp(data, sleep_req, 2) == 0) {
                BT_DBG("Peer went to sleep");
                h5->sleep = H5_SLEEPING;
                return;
        } else if (memcmp(data, woken_req, 2) == 0) {
                BT_DBG("Peer woke up");
                h5->sleep = H5_AWAKE;
        } else if (memcmp(data, wakeup_req, 2) == 0) {
                BT_DBG("Peer requested wakeup");
                h5_link_control(hu, woken_req, 2);
                h5->sleep = H5_AWAKE;
        } else {
                BT_DBG("Link Control: 0x%02hhx 0x%02hhx", data[0], data[1]);
                return;
        }

        hci_uart_tx_wakeup(hu);
}

static void h5_complete_rx_pkt(struct hci_uart *hu)
{
        struct h5 *h5 = hu->priv;
        const unsigned char *hdr = h5->rx_skb->data;

        if (H5_HDR_RELIABLE(hdr)) {
                h5->tx_ack = (h5->tx_ack + 1) % 8;
                set_bit(H5_TX_ACK_REQ, &h5->flags);
                hci_uart_tx_wakeup(hu);
        }

        h5->rx_ack = H5_HDR_ACK(hdr);

        h5_pkt_cull(h5);

        switch (H5_HDR_PKT_TYPE(hdr)) {
        case HCI_EVENT_PKT:
        case HCI_ACLDATA_PKT:
        case HCI_SCODATA_PKT:
                hci_skb_pkt_type(h5->rx_skb) = H5_HDR_PKT_TYPE(hdr);

                /* Remove Three-wire header */
                skb_pull(h5->rx_skb, 4);

                hci_recv_frame(hu->hdev, h5->rx_skb);
                h5->rx_skb = NULL;

                break;

        default:
                h5_handle_internal_rx(hu);
                break;
        }

        h5_reset_rx(h5);
}

static int h5_rx_crc(struct hci_uart *hu, unsigned char c)
{
        h5_complete_rx_pkt(hu);

        return 0;
}

static int h5_rx_payload(struct hci_uart *hu, unsigned char c)
{
        struct h5 *h5 = hu->priv;
        const unsigned char *hdr = h5->rx_skb->data;

        if (H5_HDR_CRC(hdr)) {
                h5->rx_func = h5_rx_crc;
                h5->rx_pending = 2;
        } else {
                h5_complete_rx_pkt(hu);
        }

        return 0;
}

static int h5_rx_3wire_hdr(struct hci_uart *hu, unsigned char c)
{
        struct h5 *h5 = hu->priv;
        const unsigned char *hdr = h5->rx_skb->data;

        BT_DBG("%s rx: seq %u ack %u crc %u rel %u type %u len %u",
               hu->hdev->name, H5_HDR_SEQ(hdr), H5_HDR_ACK(hdr),
               H5_HDR_CRC(hdr), H5_HDR_RELIABLE(hdr), H5_HDR_PKT_TYPE(hdr),
               H5_HDR_LEN(hdr));

        if (((hdr[0] + hdr[1] + hdr[2] + hdr[3]) & 0xff) != 0xff) {
                BT_ERR("Invalid header checksum");
                h5_reset_rx(h5);
                return 0;
        }

        if (H5_HDR_RELIABLE(hdr) && H5_HDR_SEQ(hdr) != h5->tx_ack) {
                BT_ERR("Out-of-order packet arrived (%u != %u)",
                       H5_HDR_SEQ(hdr), h5->tx_ack);
                h5_reset_rx(h5);
                return 0;
        }

        if (h5->state != H5_ACTIVE &&
            H5_HDR_PKT_TYPE(hdr) != HCI_3WIRE_LINK_PKT) {
                BT_ERR("Non-link packet received in non-active state");
                h5_reset_rx(h5);
                return 0;
        }

        h5->rx_func = h5_rx_payload;
        h5->rx_pending = H5_HDR_LEN(hdr);

        return 0;
}

static int h5_rx_pkt_start(struct hci_uart *hu, unsigned char c)
{
        struct h5 *h5 = hu->priv;

        if (c == SLIP_DELIMITER)
                return 1;

        h5->rx_func = h5_rx_3wire_hdr;
        h5->rx_pending = 4;

        h5->rx_skb = bt_skb_alloc(H5_MAX_LEN, GFP_ATOMIC);
        if (!h5->rx_skb) {
                BT_ERR("Can't allocate mem for new packet");
                h5_reset_rx(h5);
                return -ENOMEM;
        }

        h5->rx_skb->dev = (void *)hu->hdev;

        return 0;
}

static int h5_rx_delimiter(struct hci_uart *hu, unsigned char c)
{
        struct h5 *h5 = hu->priv;

        if (c == SLIP_DELIMITER)
                h5->rx_func = h5_rx_pkt_start;

        return 1;
}

static void h5_unslip_one_byte(struct h5 *h5, unsigned char c)
{
        const u8 delim = SLIP_DELIMITER, esc = SLIP_ESC;
        const u8 *byte = &c;

        if (!test_bit(H5_RX_ESC, &h5->flags) && c == SLIP_ESC) {
                set_bit(H5_RX_ESC, &h5->flags);
                return;
        }

        if (test_and_clear_bit(H5_RX_ESC, &h5->flags)) {
                switch (c) {
                case SLIP_ESC_DELIM:
                        byte = &delim;
                        break;
                case SLIP_ESC_ESC:
                        byte = &esc;
                        break;
                default:
                        BT_ERR("Invalid esc byte 0x%02hhx", c);
                        h5_reset_rx(h5);
                        return;
                }
        }

        memcpy(skb_put(h5->rx_skb, 1), byte, 1);
        h5->rx_pending--;

        BT_DBG("unsliped 0x%02hhx, rx_pending %zu", *byte, h5->rx_pending);
}

static void h5_reset_rx(struct h5 *h5)
{
        if (h5->rx_skb) {
                kfree_skb(h5->rx_skb);
                h5->rx_skb = NULL;
        }

        h5->rx_func = h5_rx_delimiter;
        h5->rx_pending = 0;
        clear_bit(H5_RX_ESC, &h5->flags);
}

static int h5_recv(struct hci_uart *hu, const void *data, int count)
{
        struct h5 *h5 = hu->priv;
        const unsigned char *ptr = data;

        BT_DBG("%s pending %zu count %d", hu->hdev->name, h5->rx_pending,
               count);

        while (count > 0) {
                int processed;

                if (h5->rx_pending > 0) {
                        if (*ptr == SLIP_DELIMITER) {
                                BT_ERR("Too short H5 packet");
                                h5_reset_rx(h5);
                                continue;
                        }

                        h5_unslip_one_byte(h5, *ptr);

                        ptr++; count--;
                        continue;
                }

                processed = h5->rx_func(hu, *ptr);
                if (processed < 0)
                        return processed;

                ptr += processed;
                count -= processed;
        }

        return 0;
}

static int h5_enqueue(struct hci_uart *hu, struct sk_buff *skb)
{
        struct h5 *h5 = hu->priv;

        if (skb->len > 0xfff) {
                BT_ERR("Packet too long (%u bytes)", skb->len);
                kfree_skb(skb);
                return 0;
        }

        if (h5->state != H5_ACTIVE) {
                BT_ERR("Ignoring HCI data in non-active state");
                kfree_skb(skb);
                return 0;
        }

        switch (hci_skb_pkt_type(skb)) {
        case HCI_ACLDATA_PKT:
        case HCI_COMMAND_PKT:
                skb_queue_tail(&h5->rel, skb);
                break;

        case HCI_SCODATA_PKT:
                skb_queue_tail(&h5->unrel, skb);
                break;

        default:
                BT_ERR("Unknown packet type %u", hci_skb_pkt_type(skb));
                kfree_skb(skb);
                break;
        }

        return 0;
}

static void h5_slip_delim(struct sk_buff *skb)
{
        const char delim = SLIP_DELIMITER;

        memcpy(skb_put(skb, 1), &delim, 1);
}

static void h5_slip_one_byte(struct sk_buff *skb, u8 c)
{
        const char esc_delim[2] = { SLIP_ESC, SLIP_ESC_DELIM };
        const char esc_esc[2] = { SLIP_ESC, SLIP_ESC_ESC };

        switch (c) {
        case SLIP_DELIMITER:
                memcpy(skb_put(skb, 2), &esc_delim, 2);
                break;
        case SLIP_ESC:
                memcpy(skb_put(skb, 2), &esc_esc, 2);
                break;
        default:
                memcpy(skb_put(skb, 1), &c, 1);
        }
}

static bool valid_packet_type(u8 type)
{
        switch (type) {
        case HCI_ACLDATA_PKT:
        case HCI_COMMAND_PKT:
        case HCI_SCODATA_PKT:
        case HCI_3WIRE_LINK_PKT:
        case HCI_3WIRE_ACK_PKT:
                return true;
        default:
                return false;
        }
}

static struct sk_buff *h5_prepare_pkt(struct hci_uart *hu, u8 pkt_type,
                                      const u8 *data, size_t len)
{
        struct h5 *h5 = hu->priv;
        struct sk_buff *nskb;
        u8 hdr[4];
        int i;

        if (!valid_packet_type(pkt_type)) {
                BT_ERR("Unknown packet type %u", pkt_type);
                return NULL;
        }

        /*
         * Max len of packet: (original len + 4 (H5 hdr) + 2 (crc)) * 2
         * (because bytes 0xc0 and 0xdb are escaped, worst case is when
         * the packet is all made of 0xc0 and 0xdb) + 2 (0xc0
         * delimiters at start and end).
         */
        nskb = alloc_skb((len + 6) * 2 + 2, GFP_ATOMIC);
        if (!nskb)
                return NULL;

        hci_skb_pkt_type(nskb) = pkt_type;

        h5_slip_delim(nskb);

        hdr[0] = h5->tx_ack << 3;
        clear_bit(H5_TX_ACK_REQ, &h5->flags);

        /* Reliable packet? */
        if (pkt_type == HCI_ACLDATA_PKT || pkt_type == HCI_COMMAND_PKT) {
                hdr[0] |= 1 << 7;
                hdr[0] |= h5->tx_seq;
                h5->tx_seq = (h5->tx_seq + 1) % 8;
        }

        hdr[1] = pkt_type | ((len & 0x0f) << 4);
        hdr[2] = len >> 4;
        hdr[3] = ~((hdr[0] + hdr[1] + hdr[2]) & 0xff);

        BT_DBG("%s tx: seq %u ack %u crc %u rel %u type %u len %u",
               hu->hdev->name, H5_HDR_SEQ(hdr), H5_HDR_ACK(hdr),
               H5_HDR_CRC(hdr), H5_HDR_RELIABLE(hdr), H5_HDR_PKT_TYPE(hdr),
               H5_HDR_LEN(hdr));

        for (i = 0; i < 4; i++)
                h5_slip_one_byte(nskb, hdr[i]);

        for (i = 0; i < len; i++)
                h5_slip_one_byte(nskb, data[i]);

        h5_slip_delim(nskb);

        return nskb;
}

static struct sk_buff *h5_dequeue(struct hci_uart *hu)
{
        struct h5 *h5 = hu->priv;
        unsigned long flags;
        struct sk_buff *skb, *nskb;

        if (h5->sleep != H5_AWAKE) {
                const unsigned char wakeup_req[] = { 0x05, 0xfa };

                if (h5->sleep == H5_WAKING_UP)
                        return NULL;

                h5->sleep = H5_WAKING_UP;
                BT_DBG("Sending wakeup request");

                mod_timer(&h5->timer, jiffies + HZ / 100);
                return h5_prepare_pkt(hu, HCI_3WIRE_LINK_PKT, wakeup_req, 2);
        }

        skb = skb_dequeue(&h5->unrel);
        if (skb) {
                nskb = h5_prepare_pkt(hu, hci_skb_pkt_type(skb),
                                      skb->data, skb->len);
                if (nskb) {
                        kfree_skb(skb);
                        return nskb;
                }

                skb_queue_head(&h5->unrel, skb);
                BT_ERR("Could not dequeue pkt because alloc_skb failed");
        }

        spin_lock_irqsave_nested(&h5->unack.lock, flags, SINGLE_DEPTH_NESTING);

        if (h5->unack.qlen >= h5->tx_win)
                goto unlock;

        skb = skb_dequeue(&h5->rel);
        if (skb) {
                nskb = h5_prepare_pkt(hu, hci_skb_pkt_type(skb),
                                      skb->data, skb->len);
                if (nskb) {
                        __skb_queue_tail(&h5->unack, skb);
                        mod_timer(&h5->timer, jiffies + H5_ACK_TIMEOUT);
                        spin_unlock_irqrestore(&h5->unack.lock, flags);
                        return nskb;
                }

                skb_queue_head(&h5->rel, skb);
                BT_ERR("Could not dequeue pkt because alloc_skb failed");
        }

unlock:
        spin_unlock_irqrestore(&h5->unack.lock, flags);

        if (test_bit(H5_TX_ACK_REQ, &h5->flags))
                return h5_prepare_pkt(hu, HCI_3WIRE_ACK_PKT, NULL, 0);

        return NULL;
}

static int h5_flush(struct hci_uart *hu)
{
        BT_DBG("hu %p", hu);
        return 0;
}

static const struct hci_uart_proto h5p = {
        .id             = HCI_UART_3WIRE,
        .name           = "Three-wire (H5)",
        .open           = h5_open,
        .close          = h5_close,
        .recv           = h5_recv,
        .enqueue        = h5_enqueue,
        .dequeue        = h5_dequeue,
        .flush          = h5_flush,
};

int __init h5_init(void)
{
        return hci_uart_register_proto(&h5p);
}

int __exit h5_deinit(void)
{
        return hci_uart_unregister_proto(&h5p);
}