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linux/drivers/net/can/dev/netlink.c
Vincent Mailhol c25cc79932 can: bittiming: add calculation for CAN FD Transmitter Delay Compensation (TDC) 
The logic for the tdco calculation is to just reuse the normal sample
point: tdco = sp. Because the sample point is expressed in tenth of
percent and the tdco is expressed in time quanta, a conversion is
needed.

At the end,
     ssp = tdcv + tdco
         = tdcv + sp.

Another popular method is to set tdco to the middle of the bit:
     tdc->tdco = can_bit_time(dbt) / 2
During benchmark tests, we could not find a clear advantages for one
of the two methods.

The tdco calculation is triggered each time the data_bittiming is
changed so that users relying on automated calculation can use the
netlink interface the exact same way without need of new parameters.
For example, a command such as:
	ip link set canX type can bitrate 500000 dbitrate 4000000 fd on
would trigger the calculation.

The user using CONFIG_CAN_CALC_BITTIMING who does not want automated
calculation needs to manually set tdco to zero.
For example with:
	ip link set canX type can tdco 0 bitrate 500000 dbitrate 4000000 fd on
(if the tdco parameter is provided in a previous command, it will be
overwritten).

If tdcv is set to zero (default), it is automatically calculated by
the transiver for each frame. As such, there is no code in the kernel
to calculate it.

tdcf has no automated calculation functions because we could not
figure out a formula for this parameter.

Link: https://lore.kernel.org/r/20210224002008.4158-6-mailhol.vincent@wanadoo.fr
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
2021-03-30 11:14:45 +02:00

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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
* Copyright (C) 2006 Andrey Volkov, Varma Electronics
* Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
*/
#include <linux/can/dev.h>
#include <net/rtnetlink.h>
static const struct nla_policy can_policy[IFLA_CAN_MAX + 1] = {
[IFLA_CAN_STATE] = { .type = NLA_U32 },
[IFLA_CAN_CTRLMODE] = { .len = sizeof(struct can_ctrlmode) },
[IFLA_CAN_RESTART_MS] = { .type = NLA_U32 },
[IFLA_CAN_RESTART] = { .type = NLA_U32 },
[IFLA_CAN_BITTIMING] = { .len = sizeof(struct can_bittiming) },
[IFLA_CAN_BITTIMING_CONST] = { .len = sizeof(struct can_bittiming_const) },
[IFLA_CAN_CLOCK] = { .len = sizeof(struct can_clock) },
[IFLA_CAN_BERR_COUNTER] = { .len = sizeof(struct can_berr_counter) },
[IFLA_CAN_DATA_BITTIMING] = { .len = sizeof(struct can_bittiming) },
[IFLA_CAN_DATA_BITTIMING_CONST] = { .len = sizeof(struct can_bittiming_const) },
[IFLA_CAN_TERMINATION] = { .type = NLA_U16 },
};
static int can_validate(struct nlattr *tb[], struct nlattr *data[],
struct netlink_ext_ack *extack)
{
bool is_can_fd = false;
/* Make sure that valid CAN FD configurations always consist of
* - nominal/arbitration bittiming
* - data bittiming
* - control mode with CAN_CTRLMODE_FD set
*/
if (!data)
return 0;
if (data[IFLA_CAN_CTRLMODE]) {
struct can_ctrlmode *cm = nla_data(data[IFLA_CAN_CTRLMODE]);
is_can_fd = cm->flags & cm->mask & CAN_CTRLMODE_FD;
}
if (is_can_fd) {
if (!data[IFLA_CAN_BITTIMING] || !data[IFLA_CAN_DATA_BITTIMING])
return -EOPNOTSUPP;
}
if (data[IFLA_CAN_DATA_BITTIMING]) {
if (!is_can_fd || !data[IFLA_CAN_BITTIMING])
return -EOPNOTSUPP;
}
return 0;
}
static int can_changelink(struct net_device *dev, struct nlattr *tb[],
struct nlattr *data[],
struct netlink_ext_ack *extack)
{
struct can_priv *priv = netdev_priv(dev);
int err;
/* We need synchronization with dev->stop() */
ASSERT_RTNL();
if (data[IFLA_CAN_BITTIMING]) {
struct can_bittiming bt;
/* Do not allow changing bittiming while running */
if (dev->flags & IFF_UP)
return -EBUSY;
/* Calculate bittiming parameters based on
* bittiming_const if set, otherwise pass bitrate
* directly via do_set_bitrate(). Bail out if neither
* is given.
*/
if (!priv->bittiming_const && !priv->do_set_bittiming)
return -EOPNOTSUPP;
memcpy(&bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(bt));
err = can_get_bittiming(dev, &bt,
priv->bittiming_const,
priv->bitrate_const,
priv->bitrate_const_cnt);
if (err)
return err;
if (priv->bitrate_max && bt.bitrate > priv->bitrate_max) {
netdev_err(dev, "arbitration bitrate surpasses transceiver capabilities of %d bps\n",
priv->bitrate_max);
return -EINVAL;
}
memcpy(&priv->bittiming, &bt, sizeof(bt));
if (priv->do_set_bittiming) {
/* Finally, set the bit-timing registers */
err = priv->do_set_bittiming(dev);
if (err)
return err;
}
}
if (data[IFLA_CAN_CTRLMODE]) {
struct can_ctrlmode *cm;
u32 ctrlstatic;
u32 maskedflags;
/* Do not allow changing controller mode while running */
if (dev->flags & IFF_UP)
return -EBUSY;
cm = nla_data(data[IFLA_CAN_CTRLMODE]);
ctrlstatic = priv->ctrlmode_static;
maskedflags = cm->flags & cm->mask;
/* check whether provided bits are allowed to be passed */
if (cm->mask & ~(priv->ctrlmode_supported | ctrlstatic))
return -EOPNOTSUPP;
/* do not check for static fd-non-iso if 'fd' is disabled */
if (!(maskedflags & CAN_CTRLMODE_FD))
ctrlstatic &= ~CAN_CTRLMODE_FD_NON_ISO;
/* make sure static options are provided by configuration */
if ((maskedflags & ctrlstatic) != ctrlstatic)
return -EOPNOTSUPP;
/* clear bits to be modified and copy the flag values */
priv->ctrlmode &= ~cm->mask;
priv->ctrlmode |= maskedflags;
/* CAN_CTRLMODE_FD can only be set when driver supports FD */
if (priv->ctrlmode & CAN_CTRLMODE_FD)
dev->mtu = CANFD_MTU;
else
dev->mtu = CAN_MTU;
}
if (data[IFLA_CAN_RESTART_MS]) {
/* Do not allow changing restart delay while running */
if (dev->flags & IFF_UP)
return -EBUSY;
priv->restart_ms = nla_get_u32(data[IFLA_CAN_RESTART_MS]);
}
if (data[IFLA_CAN_RESTART]) {
/* Do not allow a restart while not running */
if (!(dev->flags & IFF_UP))
return -EINVAL;
err = can_restart_now(dev);
if (err)
return err;
}
if (data[IFLA_CAN_DATA_BITTIMING]) {
struct can_bittiming dbt;
/* Do not allow changing bittiming while running */
if (dev->flags & IFF_UP)
return -EBUSY;
/* Calculate bittiming parameters based on
* data_bittiming_const if set, otherwise pass bitrate
* directly via do_set_bitrate(). Bail out if neither
* is given.
*/
if (!priv->data_bittiming_const && !priv->do_set_data_bittiming)
return -EOPNOTSUPP;
memcpy(&dbt, nla_data(data[IFLA_CAN_DATA_BITTIMING]),
sizeof(dbt));
err = can_get_bittiming(dev, &dbt,
priv->data_bittiming_const,
priv->data_bitrate_const,
priv->data_bitrate_const_cnt);
if (err)
return err;
if (priv->bitrate_max && dbt.bitrate > priv->bitrate_max) {
netdev_err(dev, "canfd data bitrate surpasses transceiver capabilities of %d bps\n",
priv->bitrate_max);
return -EINVAL;
}
memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));
can_calc_tdco(dev);
if (priv->do_set_data_bittiming) {
/* Finally, set the bit-timing registers */
err = priv->do_set_data_bittiming(dev);
if (err)
return err;
}
}
if (data[IFLA_CAN_TERMINATION]) {
const u16 termval = nla_get_u16(data[IFLA_CAN_TERMINATION]);
const unsigned int num_term = priv->termination_const_cnt;
unsigned int i;
if (!priv->do_set_termination)
return -EOPNOTSUPP;
/* check whether given value is supported by the interface */
for (i = 0; i < num_term; i++) {
if (termval == priv->termination_const[i])
break;
}
if (i >= num_term)
return -EINVAL;
/* Finally, set the termination value */
err = priv->do_set_termination(dev, termval);
if (err)
return err;
priv->termination = termval;
}
return 0;
}
static size_t can_get_size(const struct net_device *dev)
{
struct can_priv *priv = netdev_priv(dev);
size_t size = 0;
if (priv->bittiming.bitrate) /* IFLA_CAN_BITTIMING */
size += nla_total_size(sizeof(struct can_bittiming));
if (priv->bittiming_const) /* IFLA_CAN_BITTIMING_CONST */
size += nla_total_size(sizeof(struct can_bittiming_const));
size += nla_total_size(sizeof(struct can_clock)); /* IFLA_CAN_CLOCK */
size += nla_total_size(sizeof(u32)); /* IFLA_CAN_STATE */
size += nla_total_size(sizeof(struct can_ctrlmode)); /* IFLA_CAN_CTRLMODE */
size += nla_total_size(sizeof(u32)); /* IFLA_CAN_RESTART_MS */
if (priv->do_get_berr_counter) /* IFLA_CAN_BERR_COUNTER */
size += nla_total_size(sizeof(struct can_berr_counter));
if (priv->data_bittiming.bitrate) /* IFLA_CAN_DATA_BITTIMING */
size += nla_total_size(sizeof(struct can_bittiming));
if (priv->data_bittiming_const) /* IFLA_CAN_DATA_BITTIMING_CONST */
size += nla_total_size(sizeof(struct can_bittiming_const));
if (priv->termination_const) {
size += nla_total_size(sizeof(priv->termination)); /* IFLA_CAN_TERMINATION */
size += nla_total_size(sizeof(*priv->termination_const) * /* IFLA_CAN_TERMINATION_CONST */
priv->termination_const_cnt);
}
if (priv->bitrate_const) /* IFLA_CAN_BITRATE_CONST */
size += nla_total_size(sizeof(*priv->bitrate_const) *
priv->bitrate_const_cnt);
if (priv->data_bitrate_const) /* IFLA_CAN_DATA_BITRATE_CONST */
size += nla_total_size(sizeof(*priv->data_bitrate_const) *
priv->data_bitrate_const_cnt);
size += sizeof(priv->bitrate_max); /* IFLA_CAN_BITRATE_MAX */
return size;
}
static int can_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
struct can_priv *priv = netdev_priv(dev);
struct can_ctrlmode cm = {.flags = priv->ctrlmode};
struct can_berr_counter bec = { };
enum can_state state = priv->state;
if (priv->do_get_state)
priv->do_get_state(dev, &state);
if ((priv->bittiming.bitrate &&
nla_put(skb, IFLA_CAN_BITTIMING,
sizeof(priv->bittiming), &priv->bittiming)) ||
(priv->bittiming_const &&
nla_put(skb, IFLA_CAN_BITTIMING_CONST,
sizeof(*priv->bittiming_const), priv->bittiming_const)) ||
nla_put(skb, IFLA_CAN_CLOCK, sizeof(priv->clock), &priv->clock) ||
nla_put_u32(skb, IFLA_CAN_STATE, state) ||
nla_put(skb, IFLA_CAN_CTRLMODE, sizeof(cm), &cm) ||
nla_put_u32(skb, IFLA_CAN_RESTART_MS, priv->restart_ms) ||
(priv->do_get_berr_counter &&
!priv->do_get_berr_counter(dev, &bec) &&
nla_put(skb, IFLA_CAN_BERR_COUNTER, sizeof(bec), &bec)) ||
(priv->data_bittiming.bitrate &&
nla_put(skb, IFLA_CAN_DATA_BITTIMING,
sizeof(priv->data_bittiming), &priv->data_bittiming)) ||
(priv->data_bittiming_const &&
nla_put(skb, IFLA_CAN_DATA_BITTIMING_CONST,
sizeof(*priv->data_bittiming_const),
priv->data_bittiming_const)) ||
(priv->termination_const &&
(nla_put_u16(skb, IFLA_CAN_TERMINATION, priv->termination) ||
nla_put(skb, IFLA_CAN_TERMINATION_CONST,
sizeof(*priv->termination_const) *
priv->termination_const_cnt,
priv->termination_const))) ||
(priv->bitrate_const &&
nla_put(skb, IFLA_CAN_BITRATE_CONST,
sizeof(*priv->bitrate_const) *
priv->bitrate_const_cnt,
priv->bitrate_const)) ||
(priv->data_bitrate_const &&
nla_put(skb, IFLA_CAN_DATA_BITRATE_CONST,
sizeof(*priv->data_bitrate_const) *
priv->data_bitrate_const_cnt,
priv->data_bitrate_const)) ||
(nla_put(skb, IFLA_CAN_BITRATE_MAX,
sizeof(priv->bitrate_max),
&priv->bitrate_max))
)
return -EMSGSIZE;
return 0;
}
static size_t can_get_xstats_size(const struct net_device *dev)
{
return sizeof(struct can_device_stats);
}
static int can_fill_xstats(struct sk_buff *skb, const struct net_device *dev)
{
struct can_priv *priv = netdev_priv(dev);
if (nla_put(skb, IFLA_INFO_XSTATS,
sizeof(priv->can_stats), &priv->can_stats))
goto nla_put_failure;
return 0;
nla_put_failure:
return -EMSGSIZE;
}
static int can_newlink(struct net *src_net, struct net_device *dev,
struct nlattr *tb[], struct nlattr *data[],
struct netlink_ext_ack *extack)
{
return -EOPNOTSUPP;
}
static void can_dellink(struct net_device *dev, struct list_head *head)
{
}
struct rtnl_link_ops can_link_ops __read_mostly = {
.kind = "can",
.netns_refund = true,
.maxtype = IFLA_CAN_MAX,
.policy = can_policy,
.setup = can_setup,
.validate = can_validate,
.newlink = can_newlink,
.changelink = can_changelink,
.dellink = can_dellink,
.get_size = can_get_size,
.fill_info = can_fill_info,
.get_xstats_size = can_get_xstats_size,
.fill_xstats = can_fill_xstats,
};
int can_netlink_register(void)
{
return rtnl_link_register(&can_link_ops);
}
void can_netlink_unregister(void)
{
rtnl_link_unregister(&can_link_ops);
}
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