// SPDX-License-Identifier: GPL-2.0-only
/*
* shdlc Link Layer Control
*
* Copyright (C) 2012 Intel Corporation. All rights reserved.
*/
#define pr_fmt(fmt) "shdlc: %s: " fmt, __func__
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/skbuff.h>
#include "llc.h"
enum shdlc_state {
SHDLC_DISCONNECTED = 0,
SHDLC_CONNECTING = 1,
SHDLC_NEGOTIATING = 2,
SHDLC_HALF_CONNECTED = 3,
SHDLC_CONNECTED = 4
};
struct llc_shdlc {
struct nfc_hci_dev *hdev;
xmit_to_drv_t xmit_to_drv;
rcv_to_hci_t rcv_to_hci;
struct mutex state_mutex;
enum shdlc_state state;
int hard_fault;
wait_queue_head_t *connect_wq;
int connect_tries;
int connect_result;
struct timer_list connect_timer;/* aka T3 in spec 10.6.1 */
u8 w; /* window size */
bool srej_support;
struct timer_list t1_timer; /* send ack timeout */
bool t1_active;
struct timer_list t2_timer; /* guard/retransmit timeout */
bool t2_active;
int ns; /* next seq num for send */
int nr; /* next expected seq num for receive */
int dnr; /* oldest sent unacked seq num */
struct sk_buff_head rcv_q;
struct sk_buff_head send_q;
bool rnr; /* other side is not ready to receive */
struct sk_buff_head ack_pending_q;
struct work_struct sm_work;
int tx_headroom;
int tx_tailroom;
llc_failure_t llc_failure;
};
#define SHDLC_LLC_HEAD_ROOM 2
#define SHDLC_MAX_WINDOW 4
#define SHDLC_SREJ_SUPPORT false
#define SHDLC_CONTROL_HEAD_MASK 0xe0
#define SHDLC_CONTROL_HEAD_I 0x80
#define SHDLC_CONTROL_HEAD_I2 0xa0
#define SHDLC_CONTROL_HEAD_S 0xc0
#define SHDLC_CONTROL_HEAD_U 0xe0
#define SHDLC_CONTROL_NS_MASK 0x38
#define SHDLC_CONTROL_NR_MASK 0x07
#define SHDLC_CONTROL_TYPE_MASK 0x18
#define SHDLC_CONTROL_M_MASK 0x1f
enum sframe_type {
S_FRAME_RR = 0x00,
S_FRAME_REJ = 0x01,
S_FRAME_RNR = 0x02,
S_FRAME_SREJ = 0x03
};
enum uframe_modifier {
U_FRAME_UA = 0x06,
U_FRAME_RSET = 0x19
};
#define SHDLC_CONNECT_VALUE_MS 5
#define SHDLC_T1_VALUE_MS(w) ((5 * w) / 4)
#define SHDLC_T2_VALUE_MS 300
#define SHDLC_DUMP_SKB(info, skb) \
do { \
pr_debug("%s:\n", info); \
print_hex_dump(KERN_DEBUG, "shdlc: ", DUMP_PREFIX_OFFSET, \
16, 1, skb->data, skb->len, 0); \
} while (0)
/* checks x < y <= z modulo 8 */
static bool llc_shdlc_x_lt_y_lteq_z(int x, int y, int z)
{
if (x < z)
return ((x < y) && (y <= z)) ? true : false;
else
return ((y > x) || (y <= z)) ? true : false;
}
/* checks x <= y < z modulo 8 */
static bool llc_shdlc_x_lteq_y_lt_z(int x, int y, int z)
{
if (x <= z)
return ((x <= y) && (y < z)) ? true : false;
else /* x > z -> z+8 > x */
return ((y >= x) || (y < z)) ? true : false;
}
static struct sk_buff *llc_shdlc_alloc_skb(const struct llc_shdlc *shdlc,
int payload_len)
{
struct sk_buff *skb;
skb = alloc_skb(shdlc->tx_headroom + SHDLC_LLC_HEAD_ROOM +
shdlc->tx_tailroom + payload_len, GFP_KERNEL);
if (skb)
skb_reserve(skb, shdlc->tx_headroom + SHDLC_LLC_HEAD_ROOM);
return skb;
}
/* immediately sends an S frame. */
static int llc_shdlc_send_s_frame(const struct llc_shdlc *shdlc,
enum sframe_type sframe_type, int nr)
{
int r;
struct sk_buff *skb;
pr_debug("sframe_type=%d nr=%d\n", sframe_type, nr);
skb = llc_shdlc_alloc_skb(shdlc, 0);
if (skb == NULL)
return -ENOMEM;
*(u8 *)skb_push(skb, 1) = SHDLC_CONTROL_HEAD_S | (sframe_type << 3) | nr;
r = shdlc->xmit_to_drv(shdlc->hdev, skb);
kfree_skb(skb);
return r;
}
/* immediately sends an U frame. skb may contain optional payload */
static int llc_shdlc_send_u_frame(const struct llc_shdlc *shdlc,
struct sk_buff *skb,
enum uframe_modifier uframe_modifier)
{
int r;
pr_debug("uframe_modifier=%d\n", uframe_modifier);
*(u8 *)skb_push(skb, 1) = SHDLC_CONTROL_HEAD_U | uframe_modifier;
r = shdlc->xmit_to_drv(shdlc->hdev, skb);
kfree_skb(skb);
return r;
}
/*
* Free ack_pending frames until y_nr - 1, and reset t2 according to
* the remaining oldest ack_pending frame sent time
*/
static void llc_shdlc_reset_t2(struct llc_shdlc *shdlc, int y_nr)
{
struct sk_buff *skb;
int dnr = shdlc->dnr; /* MUST initially be < y_nr */
pr_debug("release ack pending up to frame %d excluded\n", y_nr);
while (dnr != y_nr) {
pr_debug("release ack pending frame %d\n", dnr);
skb = skb_dequeue(&shdlc->ack_pending_q);
kfree_skb(skb);
dnr = (dnr + 1) % 8;
}
if (skb_queue_empty(&shdlc->ack_pending_q)) {
if (shdlc->t2_active) {
del_timer_sync(&shdlc->t2_timer);
shdlc->t2_active = false;
pr_debug("All sent frames acked. Stopped T2(retransmit)\n");
}
} else {
skb = skb_peek(&shdlc->ack_pending_q);
mod_timer(&shdlc->t2_timer, *(unsigned long *)skb->cb +
msecs_to_jiffies(SHDLC_T2_VALUE_MS));
shdlc->t2_active = true;
pr_debug("Start T2(retransmit) for remaining unacked sent frames\n");
}
}
/*
* Receive validated frames from lower layer. skb contains HCI payload only.
* Handle according to algorithm at spec:10.8.2
*/
static void llc_shdlc_rcv_i_frame(struct llc_shdlc *shdlc,
struct sk_buff *skb, int ns, int nr)
{
int x_ns = ns;
int y_nr = nr;
pr_debug("recvd I-frame %d, remote waiting frame %d\n", ns, nr);
if (shdlc->state != SHDLC_CONNECTED)
goto exit;
if (x_ns != shdlc->nr) {
llc_shdlc_send_s_frame(shdlc, S_FRAME_REJ, shdlc->nr);
goto exit;
}
if (!shdlc->t1_active) {
shdlc->t1_active = true;
mod_timer(&shdlc->t1_timer, jiffies +
msecs_to_jiffies(SHDLC_T1_VALUE_MS(shdlc->w)));
pr_debug("(re)Start T1(send ack)\n");
}
if (skb->len) {
shdlc->rcv_to_hci(shdlc->hdev, skb);
skb = NULL;
}
shdlc->nr = (shdlc->nr + 1) % 8;
if (llc_shdlc_x_lt_y_lteq_z(shdlc->dnr, y_nr, shdlc->ns)) {
llc_shdlc_reset_t2(shdlc, y_nr);
shdlc->dnr = y_nr;
}
exit:
kfree_skb(skb);
}
static void llc_shdlc_rcv_ack(struct llc_shdlc *shdlc, int y_nr)
{
pr_debug("remote acked up to frame %d excluded\n", y_nr);
if (llc_shdlc_x_lt_y_lteq_z(shdlc->dnr, y_nr, shdlc->ns)) {
llc_shdlc_reset_t2(shdlc, y_nr);
shdlc->dnr = y_nr;
}
}
static void llc_shdlc_requeue_ack_pending(struct llc_shdlc *shdlc)
{
struct sk_buff *skb;
pr_debug("ns reset to %d\n", shdlc->dnr);
while ((skb = skb_dequeue_tail(&shdlc->ack_pending_q))) {
skb_pull(skb, 1); /* remove control field */
skb_queue_head(&shdlc->send_q, skb);
}
shdlc->ns = shdlc->dnr;
}
static void llc_shdlc_rcv_rej(struct llc_shdlc *shdlc, int y_nr)
{
struct sk_buff *skb;
pr_debug("remote asks retransmission from frame %d\n", y_nr);
if (llc_shdlc_x_lteq_y_lt_z(shdlc->dnr, y_nr, shdlc->ns)) {
if (shdlc->t2_active) {
del_timer_sync(&shdlc->t2_timer);
shdlc->t2_active = false;
pr_debug("Stopped T2(retransmit)\n");
}
if (shdlc->dnr != y_nr) {
while ((shdlc->dnr = ((shdlc->dnr + 1) % 8)) != y_nr) {
skb = skb_dequeue(&shdlc->ack_pending_q);
kfree_skb(skb);
}
}
llc_shdlc_requeue_ack_pending(shdlc);
}
}
/* See spec RR:10.8.3 REJ:10.8.4 */
static void llc_shdlc_rcv_s_frame(struct llc_shdlc *shdlc,
enum sframe_type s_frame_type, int nr)
{
struct sk_buff *skb;
if (shdlc->state != SHDLC_CONNECTED)
return;
switch (s_frame_type) {
case S_FRAME_RR:
llc_shdlc_rcv_ack(shdlc, nr);
if (shdlc->rnr == true) { /* see SHDLC 10.7.7 */
shdlc->rnr = false;
if (shdlc->send_q.qlen == 0) {
skb = llc_shdlc_alloc_skb(shdlc, 0);
if (skb)
skb_queue_tail(&shdlc->send_q, skb);
}
}
break;
case S_FRAME_REJ:
llc_shdlc_rcv_rej(shdlc, nr);
break;
case S_FRAME_RNR:
llc_shdlc_rcv_ack(shdlc, nr);
shdlc->rnr = true;
break;
default:
break;
}
}
static void llc_shdlc_connect_complete(struct llc_shdlc *shdlc, int r)
{
pr_debug("result=%d\n", r);
del_timer_sync(&shdlc->connect_timer);
if (r == 0) {
shdlc->ns = 0;
shdlc->nr = 0;
shdlc->dnr = 0;
shdlc->state = SHDLC_HALF_CONNECTED;
} else {
shdlc->state = SHDLC_DISCONNECTED;
}
shdlc->connect_result = r;
wake_up(shdlc->connect_wq);
}
static int llc_shdlc_connect_initiate(const struct llc_shdlc *shdlc)
{
struct sk_buff *skb;
skb = llc_shdlc_alloc_skb(shdlc, 2);
if (skb == NULL)
return -ENOMEM;
skb_put_u8(skb, SHDLC_MAX_WINDOW);
skb_put_u8(skb, SHDLC_SREJ_SUPPORT ? 1 : 0);
return llc_shdlc_send_u_frame(shdlc, skb, U_FRAME_RSET);
}
static int llc_shdlc_connect_send_ua(const struct llc_shdlc *shdlc)
{
struct sk_buff *skb;
skb = llc_shdlc_alloc_skb(shdlc, 0);
if (skb == NULL)
return -ENOMEM;
return llc_shdlc_send_u_frame(shdlc, skb, U_FRAME_UA);
}
static void llc_shdlc_rcv_u_frame(struct llc_shdlc *shdlc,
struct sk_buff *skb,
enum uframe_modifier u_frame_modifier)
{
u8 w = SHDLC_MAX_WINDOW;
bool srej_support = SHDLC_SREJ_SUPPORT;
int r;
pr_debug("u_frame_modifier=%d\n", u_frame_modifier);
switch (u_frame_modifier) {
case U_FRAME_RSET:
switch (shdlc->state) {
case SHDLC_NEGOTIATING:
case SHDLC_CONNECTING:
/*
* We sent RSET, but chip wants to negotiate or we
* got RSET before we managed to send out our.
*/
if (skb->len > 0)
w = skb->data[0];
if (skb->len > 1)
srej_support = skb->data[1] & 0x01 ? true :
false;
if ((w <= SHDLC_MAX_WINDOW) &&
(SHDLC_SREJ_SUPPORT || (srej_support == false))) {
shdlc->w = w;
shdlc->srej_support = srej_support;
r = llc_shdlc_connect_send_ua(shdlc);
llc_shdlc_connect_complete(shdlc, r);
}
break;
case SHDLC_HALF_CONNECTED:
/*
* Chip resent RSET due to its timeout - Ignote it
* as we already sent UA.
*/
break;
case SHDLC_CONNECTED:
/*
* Chip wants to reset link. This is unexpected and
* unsupported.
*/
shdlc->hard_fault = -ECONNRESET;
break;
default:
break;
}
break;
case U_FRAME_UA:
if ((shdlc->state == SHDLC_CONNECTING &&
shdlc->connect_tries > 0) ||
(shdlc->state == SHDLC_NEGOTIATING)) {
llc_shdlc_connect_complete(shdlc, 0);
shdlc->state = SHDLC_CONNECTED;
}
break;
default:
break;
}
kfree_skb(skb);
}
static void llc_shdlc_handle_rcv_queue(struct llc_shdlc *shdlc)
{
struct sk_buff *skb;
u8 control;
int nr;
int ns;
enum sframe_type s_frame_type;
enum uframe_modifier u_frame_modifier;
if (shdlc->rcv_q.qlen)
pr_debug("rcvQlen=%d\n", shdlc->rcv_q.qlen);
while ((skb = skb_dequeue(&shdlc->rcv_q)) != NULL) {
control = skb->data[0];
skb_pull(skb, 1);
switch (control & SHDLC_CONTROL_HEAD_MASK) {
case SHDLC_CONTROL_HEAD_I:
case SHDLC_CONTROL_HEAD_I2:
if (shdlc->state == SHDLC_HALF_CONNECTED)
shdlc->state = SHDLC_CONNECTED;
ns = (control & SHDLC_CONTROL_NS_MASK) >> 3;
nr = control & SHDLC_CONTROL_NR_MASK;
llc_shdlc_rcv_i_frame(shdlc, skb, ns, nr);
break;
case SHDLC_CONTROL_HEAD_S:
if (shdlc->state == SHDLC_HALF_CONNECTED)
shdlc->state = SHDLC_CONNECTED;
s_frame_type = (control & SHDLC_CONTROL_TYPE_MASK) >> 3;
nr = control & SHDLC_CONTROL_NR_MASK;
llc_shdlc_rcv_s_frame(shdlc, s_frame_type, nr);
kfree_skb(skb);
break;
case SHDLC_CONTROL_HEAD_U:
u_frame_modifier = control & SHDLC_CONTROL_M_MASK;
llc_shdlc_rcv_u_frame(shdlc, skb, u_frame_modifier);
break;
default:
pr_err("UNKNOWN Control=%d\n", control);
kfree_skb(skb);
break;
}
}
}
static int llc_shdlc_w_used(int ns, int dnr)
{
int unack_count;
if (dnr <= ns)
unack_count = ns - dnr;
else
unack_count = 8 - dnr + ns;
return unack_count;
}
/* Send frames according to algorithm at spec:10.8.1 */
static void llc_shdlc_handle_send_queue(struct llc_shdlc *shdlc)
{
struct sk_buff *skb;
int r;
unsigned long time_sent;
if (shdlc->send_q.qlen)
pr_debug("sendQlen=%d ns=%d dnr=%d rnr=%s w_room=%d unackQlen=%d\n",
shdlc->send_q.qlen, shdlc->ns, shdlc->dnr,
shdlc->rnr == false ? "false" : "true",
shdlc->w - llc_shdlc_w_used(shdlc->ns, shdlc->dnr),
shdlc->ack_pending_q.qlen);
while (shdlc->send_q.qlen && shdlc->ack_pending_q.qlen < shdlc->w &&
(shdlc->rnr == false)) {
if (shdlc->t1_active) {
del_timer_sync(&shdlc->t1_timer);
shdlc->t1_active = false;
pr_debug("Stopped T1(send ack)\n");
}
skb = skb_dequeue(&shdlc->send_q);
*(u8 *)skb_push(skb, 1) = SHDLC_CONTROL_HEAD_I | (shdlc->ns << 3) |
shdlc->nr;
pr_debug("Sending I-Frame %d, waiting to rcv %d\n", shdlc->ns,
shdlc->nr);
SHDLC_DUMP_SKB("shdlc frame written", skb);
r = shdlc->xmit_to_drv(shdlc->hdev, skb);
if (r < 0) {
shdlc->hard_fault = r;
break;
}
shdlc->ns = (shdlc->ns + 1) % 8;
time_sent = jiffies;
*(unsigned long *)skb->cb = time_sent;
skb_queue_tail(&shdlc->ack_pending_q, skb);
if (shdlc->t2_active == false) {
shdlc->t2_active = true;
mod_timer(&shdlc->t2_timer, time_sent +
msecs_to_jiffies(SHDLC_T2_VALUE_MS));
pr_debug("Started T2 (retransmit)\n");
}
}
}
static void llc_shdlc_connect_timeout(struct timer_list *t)
{
struct llc_shdlc *shdlc = from_timer(shdlc, t, connect_timer);
schedule_work(&shdlc->sm_work);
}
static void llc_shdlc_t1_timeout(struct timer_list *t)
{
struct llc_shdlc *shdlc = from_timer(shdlc, t, t1_timer);
pr_debug("SoftIRQ: need to send ack\n");
schedule_work(&shdlc->sm_work);
}
static void llc_shdlc_t2_timeout(struct timer_list *t)
{
struct llc_shdlc *shdlc = from_timer(shdlc, t, t2_timer);
pr_debug("SoftIRQ: need to retransmit\n");
schedule_work(&shdlc->sm_work);
}
static void llc_shdlc_sm_work(struct work_struct *work)
{
struct llc_shdlc *shdlc = container_of(work, struct llc_shdlc, sm_work);
int r;
mutex_lock(&shdlc->state_mutex);
switch (shdlc->state) {
case SHDLC_DISCONNECTED:
skb_queue_purge(&shdlc->rcv_q);
skb_queue_purge(&shdlc->send_q);
skb_queue_purge(&shdlc->ack_pending_q);
break;
case SHDLC_CONNECTING:
if (shdlc->hard_fault) {
llc_shdlc_connect_complete(shdlc, shdlc->hard_fault);
break;
}
if (shdlc->connect_tries++ < 5)
r = llc_shdlc_connect_initiate(shdlc);
else
r = -ETIME;
if (r < 0) {
llc_shdlc_connect_complete(shdlc, r);
} else {
mod_timer(&shdlc->connect_timer, jiffies +
msecs_to_jiffies(SHDLC_CONNECT_VALUE_MS));
shdlc->state = SHDLC_NEGOTIATING;
}
break;
case SHDLC_NEGOTIATING:
if (timer_pending(&shdlc->connect_timer) == 0) {
shdlc->state = SHDLC_CONNECTING;
schedule_work(&shdlc->sm_work);
}
llc_shdlc_handle_rcv_queue(shdlc);
if (shdlc->hard_fault) {
llc_shdlc_connect_complete(shdlc, shdlc->hard_fault);
break;
}
break;
case SHDLC_HALF_CONNECTED:
case SHDLC_CONNECTED:
llc_shdlc_handle_rcv_queue(shdlc);
llc_shdlc_handle_send_queue(shdlc);
if (shdlc->t1_active && timer_pending(&shdlc->t1_timer) == 0) {
pr_debug("Handle T1(send ack) elapsed (T1 now inactive)\n");
shdlc->t1_active = false;
r = llc_shdlc_send_s_frame(shdlc, S_FRAME_RR,
shdlc->nr);
if (r < 0)
shdlc->hard_fault = r;
}
if (shdlc->t2_active && timer_pending(&shdlc->t2_timer) == 0) {
pr_debug("Handle T2(retransmit) elapsed (T2 inactive)\n");
shdlc->t2_active = false;
llc_shdlc_requeue_ack_pending(shdlc);
llc_shdlc_handle_send_queue(shdlc);
}
if (shdlc->hard_fault)
shdlc->llc_failure(shdlc->hdev, shdlc->hard_fault);
break;
default:
break;
}
mutex_unlock(&shdlc->state_mutex);
}
/*
* Called from syscall context to establish shdlc link. Sleeps until
* link is ready or failure.
*/
static int llc_shdlc_connect(struct llc_shdlc *shdlc)
{
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(connect_wq);
mutex_lock(&shdlc->state_mutex);
shdlc->state = SHDLC_CONNECTING;
shdlc->connect_wq = &connect_wq;
shdlc->connect_tries = 0;
shdlc->connect_result = 1;
mutex_unlock(&shdlc->state_mutex);
schedule_work(&shdlc->sm_work);
wait_event(connect_wq, shdlc->connect_result != 1);
return shdlc->connect_result;
}
static void llc_shdlc_disconnect(struct llc_shdlc *shdlc)
{
mutex_lock(&shdlc->state_mutex);
shdlc->state = SHDLC_DISCONNECTED;
mutex_unlock(&shdlc->state_mutex);
schedule_work(&shdlc->sm_work);
}
/*
* Receive an incoming shdlc frame. Frame has already been crc-validated.
* skb contains only LLC header and payload.
* If skb == NULL, it is a notification that the link below is dead.
*/
static void llc_shdlc_recv_frame(struct llc_shdlc *shdlc, struct sk_buff *skb)
{
if (skb == NULL) {
pr_err("NULL Frame -> link is dead\n");
shdlc->hard_fault = -EREMOTEIO;
} else {
SHDLC_DUMP_SKB("incoming frame", skb);
skb_queue_tail(&shdlc->rcv_q, skb);
}
schedule_work(&shdlc->sm_work);
}
static void *llc_shdlc_init(struct nfc_hci_dev *hdev, xmit_to_drv_t xmit_to_drv,
rcv_to_hci_t rcv_to_hci, int tx_headroom,
int tx_tailroom, int *rx_headroom, int *rx_tailroom,
llc_failure_t llc_failure)
{
struct llc_shdlc *shdlc;
*rx_headroom = SHDLC_LLC_HEAD_ROOM;
*rx_tailroom = 0;
shdlc = kzalloc(sizeof(struct llc_shdlc), GFP_KERNEL);
if (shdlc == NULL)
return NULL;
mutex_init(&shdlc->state_mutex);
shdlc->state = SHDLC_DISCONNECTED;
timer_setup(&shdlc->connect_timer, llc_shdlc_connect_timeout, 0);
timer_setup(&shdlc->t1_timer, llc_shdlc_t1_timeout, 0);
timer_setup(&shdlc->t2_timer, llc_shdlc_t2_timeout, 0);
shdlc->w = SHDLC_MAX_WINDOW;
shdlc->srej_support = SHDLC_SREJ_SUPPORT;
skb_queue_head_init(&shdlc->rcv_q);
skb_queue_head_init(&shdlc->send_q);
skb_queue_head_init(&shdlc->ack_pending_q);
INIT_WORK(&shdlc->sm_work, llc_shdlc_sm_work);
shdlc->hdev = hdev;
shdlc->xmit_to_drv = xmit_to_drv;
shdlc->rcv_to_hci = rcv_to_hci;
shdlc->tx_headroom = tx_headroom;
shdlc->tx_tailroom = tx_tailroom;
shdlc->llc_failure = llc_failure;
return shdlc;
}
static void llc_shdlc_deinit(struct nfc_llc *llc)
{
struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
skb_queue_purge(&shdlc->rcv_q);
skb_queue_purge(&shdlc->send_q);
skb_queue_purge(&shdlc->ack_pending_q);
kfree(shdlc);
}
static int llc_shdlc_start(struct nfc_llc *llc)
{
struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
return llc_shdlc_connect(shdlc);
}
static int llc_shdlc_stop(struct nfc_llc *llc)
{
struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
llc_shdlc_disconnect(shdlc);
return 0;
}
static void llc_shdlc_rcv_from_drv(struct nfc_llc *llc, struct sk_buff *skb)
{
struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
llc_shdlc_recv_frame(shdlc, skb);
}
static int llc_shdlc_xmit_from_hci(struct nfc_llc *llc, struct sk_buff *skb)
{
struct llc_shdlc *shdlc = nfc_llc_get_data(llc);
skb_queue_tail(&shdlc->send_q, skb);
schedule_work(&shdlc->sm_work);
return 0;
}
static const struct nfc_llc_ops llc_shdlc_ops = {
.init = llc_shdlc_init,
.deinit = llc_shdlc_deinit,
.start = llc_shdlc_start,
.stop = llc_shdlc_stop,
.rcv_from_drv = llc_shdlc_rcv_from_drv,
.xmit_from_hci = llc_shdlc_xmit_from_hci,
};
int nfc_llc_shdlc_register(void)
{
return nfc_llc_register(LLC_SHDLC_NAME, &llc_shdlc_ops);
}
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