linux/drivers/bluetooth/hci_h5.c

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/*
*
* 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
#define H5_TXWINSIZE 4
#define H5_ACK_TIMEOUT msecs_to_jiffies(250)
/*
* Maximum Three-wire packet:
* 4 byte header + max value for 12-bit length + 2 bytes for CRC
*/
#define H5_MAX_LEN (4 + 0xfff + 2)
#define SLIP_DELIMITER 0xc0
#define SLIP_ESC 0xdb
#define SLIP_ESC_DELIM 0xdc
#define SLIP_ESC_ESC 0xdd
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 */
struct sk_buff *rx_skb; /* Receive buffer */
size_t rx_pending; /* Expecting more bytes */
bool rx_esc; /* SLIP escape mode */
int (*rx_func) (struct hci_uart *hu, u8 c);
struct timer_list timer; /* Retransmission timer */
bool txack_req;
u8 next_ack;
u8 next_seq;
};
static void h5_reset_rx(struct h5 *h5);
static void h5_timed_event(unsigned long arg)
{
struct hci_uart *hu = (struct hci_uart *) arg;
struct h5 *h5 = hu->priv;
struct sk_buff *skb;
unsigned long flags;
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->next_seq = (h5->next_seq - 1) & 0x07;
skb_queue_head(&h5->rel, skb);
}
spin_unlock_irqrestore(&h5->unack.lock, flags);
hci_uart_tx_wakeup(hu);
}
static int h5_open(struct hci_uart *hu)
{
struct h5 *h5;
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);
init_timer(&h5->timer);
h5->timer.function = h5_timed_event;
h5->timer.data = (unsigned long) hu;
return 0;
}
static int h5_close(struct hci_uart *hu)
{
struct h5 *h5 = hu->priv;
skb_queue_purge(&h5->unack);
skb_queue_purge(&h5->rel);
skb_queue_purge(&h5->unrel);
del_timer(&h5->timer);
kfree(h5);
return 0;
}
static void h5_handle_internal_rx(struct hci_uart *hu)
{
BT_DBG("%s", hu->hdev->name);
}
static void h5_complete_rx_pkt(struct hci_uart *hu)
{
struct h5 *h5 = hu->priv;
u8 pkt_type;
BT_DBG("%s", hu->hdev->name);
pkt_type = h5->rx_skb->data[1] & 0x0f;
switch (pkt_type) {
case HCI_EVENT_PKT:
case HCI_ACLDATA_PKT:
case HCI_SCODATA_PKT:
bt_cb(h5->rx_skb)->pkt_type = pkt_type;
/* Remove Three-wire header */
skb_pull(h5->rx_skb, 4);
hci_recv_frame(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)
{
struct h5 *h5 = hu->priv;
BT_DBG("%s 0x%02hhx", hu->hdev->name, c);
h5_complete_rx_pkt(hu);
h5_reset_rx(h5);
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;
BT_DBG("%s 0x%02hhx", hu->hdev->name, c);
if ((hdr[0] >> 4) & 0x01) {
h5->rx_func = h5_rx_crc;
h5->rx_pending = 2;
} else {
h5_complete_rx_pkt(hu);
h5_reset_rx(h5);
}
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 0x%02hhx", hu->hdev->name, c);
if (((hdr[0] + hdr[1] + hdr[2] + hdr[3]) & 0xff) != 0xff) {
BT_ERR("Invalid header checksum");
h5_reset_rx(h5);
return 0;
}
h5->rx_func = h5_rx_payload;
h5->rx_pending = ((hdr[1] >> 4) & 0xff) + (hdr[2] << 4);
return 0;
}
static int h5_rx_pkt_start(struct hci_uart *hu, unsigned char c)
{
struct h5 *h5 = hu->priv;
BT_DBG("%s 0x%02hhx", hu->hdev->name, c);
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;
BT_DBG("%s 0x%02hhx", hu->hdev->name, c);
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 (!h5->rx_esc && c == SLIP_ESC) {
h5->rx_esc = true;
return;
}
if (h5->rx_esc) {
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;
}
h5->rx_esc = false;
}
memcpy(skb_put(h5->rx_skb, 1), byte, 1);
h5->rx_pending--;
BT_DBG("unsliped 0x%02hhx", *byte);
}
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;
h5->rx_esc = false;
}
static int h5_recv(struct hci_uart *hu, void *data, int count)
{
struct h5 *h5 = hu->priv;
unsigned char *ptr = data;
BT_DBG("%s count %d", hu->hdev->name, 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;
}
switch (bt_cb(skb)->pkt_type) {
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", bt_cb(skb)->pkt_type);
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 struct sk_buff *h5_build_pkt(struct h5 *h5, bool rel, u8 pkt_type,
const u8 *data, size_t len)
{
struct sk_buff *nskb;
u8 hdr[4];
int i;
/*
* 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;
bt_cb(nskb)->pkt_type = pkt_type;
h5_slip_delim(nskb);
hdr[0] = h5->next_ack << 3;
h5->txack_req = false;
if (rel) {
hdr[0] |= 1 << 7;
hdr[0] |= h5->next_seq;
h5->next_seq = (h5->next_seq + 1) % 8;
}
hdr[1] = pkt_type | ((len & 0x0f) << 4);
hdr[2] = len >> 4;
hdr[3] = ~((hdr[0] + hdr[1] + hdr[2]) & 0xff);
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_prepare_pkt(struct h5 *h5, u8 pkt_type,
const u8 *data, size_t len)
{
bool rel;
switch (pkt_type) {
case HCI_ACLDATA_PKT:
case HCI_COMMAND_PKT:
rel = true;
break;
case HCI_SCODATA_PKT:
case HCI_3WIRE_LINK_PKT:
case HCI_3WIRE_ACK_PKT:
rel = false;
break;
default:
BT_ERR("Unknown packet type %u", pkt_type);
return NULL;
}
return h5_build_pkt(h5, rel, pkt_type, data, len);
}
static struct sk_buff *h5_prepare_ack(struct h5 *h5)
{
h5->txack_req = false;
return NULL;
}
static struct sk_buff *h5_dequeue(struct hci_uart *hu)
{
struct h5 *h5 = hu->priv;
unsigned long flags;
struct sk_buff *skb, *nskb;
if ((skb = skb_dequeue(&h5->unrel)) != NULL) {
nskb = h5_prepare_pkt(h5, bt_cb(skb)->pkt_type,
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_TXWINSIZE)
goto unlock;
if ((skb = skb_dequeue(&h5->rel)) != NULL) {
nskb = h5_prepare_pkt(h5, bt_cb(skb)->pkt_type,
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 (h5->txack_req)
return h5_prepare_ack(h5);
return NULL;
}
static int h5_flush(struct hci_uart *hu)
{
BT_DBG("hu %p", hu);
return 0;
}
static struct hci_uart_proto h5p = {
.id = HCI_UART_3WIRE,
.open = h5_open,
.close = h5_close,
.recv = h5_recv,
.enqueue = h5_enqueue,
.dequeue = h5_dequeue,
.flush = h5_flush,
};
int __init h5_init(void)
{
int err = hci_uart_register_proto(&h5p);
if (!err)
BT_INFO("HCI Three-wire UART (H5) protocol initialized");
else
BT_ERR("HCI Three-wire UART (H5) protocol init failed");
return err;
}
int __exit h5_deinit(void)
{
return hci_uart_unregister_proto(&h5p);
}