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can: slcan: allow to send commands to the adapter

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This is a preparation patch for the upcoming support to change the
bitrate via ip tool, reset the adapter error states via the ethtool API
and, more generally, send commands to the adapter.

Since the close command (i. e. "C\r") will be sent in the ndo_stop()
where netif_running() returns false, a new flag bit (i. e. SLF_XCMD) for
serial transmission has to be added.

Link: https://lore.kernel.org/all/20220628163137.413025-7-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Tested-by: Jeroen Hofstee <jhofstee@victronenergy.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Dario Binacchi 2022-06-28 18:31:30 +02:00 committed by Marc Kleine-Budde
parent c4e54b063f
commit 52f9ac85b8
1 changed files with 45 additions and 1 deletions
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46
drivers/net/can/slcan.c
View file

@ -97,6 +97,9 @@ struct slcan {
unsigned long flags; /* Flag values/ mode etc */
#define SLF_INUSE 0 /* Channel in use */
#define SLF_ERROR 1 /* Parity, etc. error */
#define SLF_XCMD 2 /* Command transmission */
wait_queue_head_t xcmd_wait; /* Wait queue for commands */
/* transmission */
};
static struct net_device **slcan_devs;
@ -314,12 +317,22 @@ static void slcan_transmit(struct work_struct *work)
spin_lock_bh(&sl->lock);
/* First make sure we're connected. */
if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) {
if (!sl->tty || sl->magic != SLCAN_MAGIC ||
(unlikely(!netif_running(sl->dev)) &&
likely(!test_bit(SLF_XCMD, &sl->flags)))) {
spin_unlock_bh(&sl->lock);
return;
}
if (sl->xleft <= 0) {
if (unlikely(test_bit(SLF_XCMD, &sl->flags))) {
clear_bit(SLF_XCMD, &sl->flags);
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
spin_unlock_bh(&sl->lock);
wake_up(&sl->xcmd_wait);
return;
}
/* Now serial buffer is almost free & we can start
* transmission of another packet */
sl->dev->stats.tx_packets++;
@ -383,6 +396,36 @@ static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
* Routines looking at netdevice side.
******************************************/
static int slcan_transmit_cmd(struct slcan *sl, const unsigned char *cmd)
{
int ret, actual, n;
spin_lock(&sl->lock);
if (!sl->tty) {
spin_unlock(&sl->lock);
return -ENODEV;
}
n = snprintf(sl->xbuff, sizeof(sl->xbuff), "%s", cmd);
set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
actual = sl->tty->ops->write(sl->tty, sl->xbuff, n);
sl->xleft = n - actual;
sl->xhead = sl->xbuff + actual;
set_bit(SLF_XCMD, &sl->flags);
spin_unlock(&sl->lock);
ret = wait_event_interruptible_timeout(sl->xcmd_wait,
!test_bit(SLF_XCMD, &sl->flags),
HZ);
clear_bit(SLF_XCMD, &sl->flags);
if (ret == -ERESTARTSYS)
return ret;
if (ret == 0)
return -ETIMEDOUT;
return 0;
}
/* Netdevice UP -> DOWN routine */
static int slc_close(struct net_device *dev)
{
@ -540,6 +583,7 @@ static struct slcan *slc_alloc(void)
sl->dev = dev;
spin_lock_init(&sl->lock);
INIT_WORK(&sl->tx_work, slcan_transmit);
init_waitqueue_head(&sl->xcmd_wait);
slcan_devs[i] = dev;
return sl;