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can: isotp: add support for transmission without flow control
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Usually the ISO 15765-2 protocol is a point-to-point protocol to transfer
segmented PDUs to a dedicated receiver. This receiver sends a flow control
message to specify protocol options and timings (e.g. block size / STmin).

The so called functional addressing communication allows a 1:N
communication but is limited to a single frame length.

This new CAN_ISOTP_CF_BROADCAST allows an unconfirmed 1:N communication
with PDU length that would not fit into a single frame. This feature is
not covered by the ISO 15765-2 standard.

Link: https://lore.kernel.org/all/20220507115558.19065-1-socketcan@hartkopp.net
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
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@hartkopp @marckleinebudde
hartkopp authored and marckleinebudde committed May 16, 2022
1 parent 51a0d5e commit 9f39d36
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Showing 2 changed files with 92 additions and 33 deletions.
25 changes: 13 additions & 12 deletions include/uapi/linux/can/isotp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -124,18 +124,19 @@ struct can_isotp_ll_options {

/* flags for isotp behaviour */

#define CAN_ISOTP_LISTEN_MODE 0x001 /* listen only (do not send FC) */
#define CAN_ISOTP_EXTEND_ADDR 0x002 /* enable extended addressing */
#define CAN_ISOTP_TX_PADDING 0x004 /* enable CAN frame padding tx path */
#define CAN_ISOTP_RX_PADDING 0x008 /* enable CAN frame padding rx path */
#define CAN_ISOTP_CHK_PAD_LEN 0x010 /* check received CAN frame padding */
#define CAN_ISOTP_CHK_PAD_DATA 0x020 /* check received CAN frame padding */
#define CAN_ISOTP_HALF_DUPLEX 0x040 /* half duplex error state handling */
#define CAN_ISOTP_FORCE_TXSTMIN 0x080 /* ignore stmin from received FC */
#define CAN_ISOTP_FORCE_RXSTMIN 0x100 /* ignore CFs depending on rx stmin */
#define CAN_ISOTP_RX_EXT_ADDR 0x200 /* different rx extended addressing */
#define CAN_ISOTP_WAIT_TX_DONE 0x400 /* wait for tx completion */
#define CAN_ISOTP_SF_BROADCAST 0x800 /* 1-to-N functional addressing */
#define CAN_ISOTP_LISTEN_MODE 0x0001 /* listen only (do not send FC) */
#define CAN_ISOTP_EXTEND_ADDR 0x0002 /* enable extended addressing */
#define CAN_ISOTP_TX_PADDING 0x0004 /* enable CAN frame padding tx path */
#define CAN_ISOTP_RX_PADDING 0x0008 /* enable CAN frame padding rx path */
#define CAN_ISOTP_CHK_PAD_LEN 0x0010 /* check received CAN frame padding */
#define CAN_ISOTP_CHK_PAD_DATA 0x0020 /* check received CAN frame padding */
#define CAN_ISOTP_HALF_DUPLEX 0x0040 /* half duplex error state handling */
#define CAN_ISOTP_FORCE_TXSTMIN 0x0080 /* ignore stmin from received FC */
#define CAN_ISOTP_FORCE_RXSTMIN 0x0100 /* ignore CFs depending on rx stmin */
#define CAN_ISOTP_RX_EXT_ADDR 0x0200 /* different rx extended addressing */
#define CAN_ISOTP_WAIT_TX_DONE 0x0400 /* wait for tx completion */
#define CAN_ISOTP_SF_BROADCAST 0x0800 /* 1-to-N functional addressing */
#define CAN_ISOTP_CF_BROADCAST 0x1000 /* 1-to-N transmission w/o FC */

/* protocol machine default values */

Expand Down
100 changes: 79 additions & 21 deletions net/can/isotp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,7 @@ MODULE_ALIAS("can-proto-6");
#define FC_CONTENT_SZ 3 /* flow control content size in byte (FS/BS/STmin) */

#define ISOTP_CHECK_PADDING (CAN_ISOTP_CHK_PAD_LEN | CAN_ISOTP_CHK_PAD_DATA)
#define ISOTP_ALL_BC_FLAGS (CAN_ISOTP_SF_BROADCAST | CAN_ISOTP_CF_BROADCAST)

/* Flow Status given in FC frame */
#define ISOTP_FC_CTS 0 /* clear to send */
Expand Down Expand Up @@ -159,6 +160,23 @@ static inline struct isotp_sock *isotp_sk(const struct sock *sk)
return (struct isotp_sock *)sk;
}

static u32 isotp_bc_flags(struct isotp_sock *so)
{
return so->opt.flags & ISOTP_ALL_BC_FLAGS;
}

static bool isotp_register_rxid(struct isotp_sock *so)
{
/* no broadcast modes => register rx_id for FC frame reception */
return (isotp_bc_flags(so) == 0);
}

static bool isotp_register_txecho(struct isotp_sock *so)
{
/* all modes but SF_BROADCAST register for tx echo skbs */
return (isotp_bc_flags(so) != CAN_ISOTP_SF_BROADCAST);
}

static enum hrtimer_restart isotp_rx_timer_handler(struct hrtimer *hrtimer)
{
struct isotp_sock *so = container_of(hrtimer, struct isotp_sock,
Expand Down Expand Up @@ -803,7 +821,6 @@ static void isotp_create_fframe(struct canfd_frame *cf, struct isotp_sock *so,
cf->data[i] = so->tx.buf[so->tx.idx++];

so->tx.sn = 1;
so->tx.state = ISOTP_WAIT_FIRST_FC;
}

static void isotp_rcv_echo(struct sk_buff *skb, void *data)
Expand Down Expand Up @@ -936,7 +953,7 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
off = (so->tx.ll_dl > CAN_MAX_DLEN) ? 1 : 0;

/* does the given data fit into a single frame for SF_BROADCAST? */
if ((so->opt.flags & CAN_ISOTP_SF_BROADCAST) &&
if ((isotp_bc_flags(so) == CAN_ISOTP_SF_BROADCAST) &&
(size > so->tx.ll_dl - SF_PCI_SZ4 - ae - off)) {
err = -EINVAL;
goto err_out_drop;
Expand Down Expand Up @@ -1000,12 +1017,41 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
/* don't enable wait queue for a single frame transmission */
wait_tx_done = 0;
} else {
/* send first frame and wait for FC */
/* send first frame */

isotp_create_fframe(cf, so, ae);

/* start timeout for FC */
hrtimer_sec = 1;
if (isotp_bc_flags(so) == CAN_ISOTP_CF_BROADCAST) {
/* set timer for FC-less operation (STmin = 0) */
if (so->opt.flags & CAN_ISOTP_FORCE_TXSTMIN)
so->tx_gap = ktime_set(0, so->force_tx_stmin);
else
so->tx_gap = ktime_set(0, so->frame_txtime);

/* disable wait for FCs due to activated block size */
so->txfc.bs = 0;

/* cfecho should have been zero'ed by init */
if (so->cfecho)
pr_notice_once("can-isotp: no fc cfecho %08X\n",
so->cfecho);

/* set consecutive frame echo tag */
so->cfecho = *(u32 *)cf->data;

/* switch directly to ISOTP_SENDING state */
so->tx.state = ISOTP_SENDING;

/* start timeout for unlikely lost echo skb */
hrtimer_sec = 2;
} else {
/* standard flow control check */
so->tx.state = ISOTP_WAIT_FIRST_FC;

/* start timeout for FC */
hrtimer_sec = 1;
}

hrtimer_start(&so->txtimer, ktime_set(hrtimer_sec, 0),
HRTIMER_MODE_REL_SOFT);
}
Expand All @@ -1025,6 +1071,9 @@ static int isotp_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
if (hrtimer_sec)
hrtimer_cancel(&so->txtimer);

/* reset consecutive frame echo tag */
so->cfecho = 0;

goto err_out_drop;
}

Expand Down Expand Up @@ -1120,15 +1169,17 @@ static int isotp_release(struct socket *sock)
lock_sock(sk);

/* remove current filters & unregister */
if (so->bound && (!(so->opt.flags & CAN_ISOTP_SF_BROADCAST))) {
if (so->bound && isotp_register_txecho(so)) {
if (so->ifindex) {
struct net_device *dev;

dev = dev_get_by_index(net, so->ifindex);
if (dev) {
can_rx_unregister(net, dev, so->rxid,
SINGLE_MASK(so->rxid),
isotp_rcv, sk);
if (isotp_register_rxid(so))
can_rx_unregister(net, dev, so->rxid,
SINGLE_MASK(so->rxid),
isotp_rcv, sk);

can_rx_unregister(net, dev, so->txid,
SINGLE_MASK(so->txid),
isotp_rcv_echo, sk);
Expand Down Expand Up @@ -1164,7 +1215,6 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
canid_t tx_id, rx_id;
int err = 0;
int notify_enetdown = 0;
int do_rx_reg = 1;

if (len < ISOTP_MIN_NAMELEN)
return -EINVAL;
Expand Down Expand Up @@ -1192,12 +1242,8 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)
goto out;
}

/* do not register frame reception for functional addressing */
if (so->opt.flags & CAN_ISOTP_SF_BROADCAST)
do_rx_reg = 0;

/* do not validate rx address for functional addressing */
if (do_rx_reg && rx_id == tx_id) {
/* ensure different CAN IDs when the rx_id is to be registered */
if (isotp_register_rxid(so) && rx_id == tx_id) {
err = -EADDRNOTAVAIL;
goto out;
}
Expand All @@ -1222,10 +1268,11 @@ static int isotp_bind(struct socket *sock, struct sockaddr *uaddr, int len)

ifindex = dev->ifindex;

if (do_rx_reg) {
if (isotp_register_rxid(so))
can_rx_register(net, dev, rx_id, SINGLE_MASK(rx_id),
isotp_rcv, sk, "isotp", sk);

if (isotp_register_txecho(so)) {
/* no consecutive frame echo skb in flight */
so->cfecho = 0;

Expand Down Expand Up @@ -1294,6 +1341,15 @@ static int isotp_setsockopt_locked(struct socket *sock, int level, int optname,
if (!(so->opt.flags & CAN_ISOTP_RX_EXT_ADDR))
so->opt.rx_ext_address = so->opt.ext_address;

/* these broadcast flags are not allowed together */
if (isotp_bc_flags(so) == ISOTP_ALL_BC_FLAGS) {
/* CAN_ISOTP_SF_BROADCAST is prioritized */
so->opt.flags &= ~CAN_ISOTP_CF_BROADCAST;

/* give user feedback on wrong config attempt */
ret = -EINVAL;
}

/* check for frame_txtime changes (0 => no changes) */
if (so->opt.frame_txtime) {
if (so->opt.frame_txtime == CAN_ISOTP_FRAME_TXTIME_ZERO)
Expand Down Expand Up @@ -1444,10 +1500,12 @@ static void isotp_notify(struct isotp_sock *so, unsigned long msg,
case NETDEV_UNREGISTER:
lock_sock(sk);
/* remove current filters & unregister */
if (so->bound && (!(so->opt.flags & CAN_ISOTP_SF_BROADCAST))) {
can_rx_unregister(dev_net(dev), dev, so->rxid,
SINGLE_MASK(so->rxid),
isotp_rcv, sk);
if (so->bound && isotp_register_txecho(so)) {
if (isotp_register_rxid(so))
can_rx_unregister(dev_net(dev), dev, so->rxid,
SINGLE_MASK(so->rxid),
isotp_rcv, sk);

can_rx_unregister(dev_net(dev), dev, so->txid,
SINGLE_MASK(so->txid),
isotp_rcv_echo, sk);
Expand Down

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