With this series I try to finish the task, started with the series [1],
of completely removing the dependency of the slcan driver from the
userspace slcand/slcan_attach applications.
The series, however, still lacks a patch for sending the bitrate setting
command to the adapter:
slcan_attach -b <btr> <dev>
Without at least this patch the task cannot be considered truly completed.
The idea I got is that this can only happen through the ethtool API.
Among the various operations made available by this interface I would
have used the set_regs (but only the get_regs has been developed), or,
the set_eeprom, even if the setting would not be stored in an eeprom.
IMHO it would take a set_regs operation with a `struct ethtool_wregs'
parameter similar to `struct ethtool_eeprom' without the magic field:
struct ethtool_wregs {
__u32 cmd;
__u32 offset;
__u32 len;
__u8 data[0];
};
But I am not the expert and if there was an alternative solution already
usable, it would be welcome.
The series also contains patches that remove the legacy stuff (slcan_devs,
SLCAN_MAGIC, ...) and do some module cleanup.
The series has been created on top of the patches:
can: slcan: convert comments to network style comments
can: slcan: slcan_init() convert printk(LEVEL ...) to pr_level()
can: slcan: fix whitespace issues
can: slcan: convert comparison to NULL into !val
can: slcan: clean up if/else
can: slcan: use scnprintf() as a hardening measure
can: slcan: do not report txerr and rxerr during bus-off
can: slcan: do not sleep with a spin lock held
applied to linux-next.
[1] https://lore.kernel.org/all/[email protected]/
Changes in v2:
- Re-add headers that export at least one symbol used by the module.
- Update the commit description.
- Drop the old "slcan" name to use the standard canX interface naming.
- Remove comment on listen-only command.
- Update the commit subject and description.
- Add the patch "MAINTAINERS: Add myself as maintainer of the SLCAN driver"
to the series.
Dario Binacchi (6):
can: slcan: remove useless header inclusions
can: slcan: remove legacy infrastructure
can: slcan: change every `slc' occurrence in `slcan'
can: slcan: use the generic can_change_mtu()
can: slcan: add support for listen-only mode
MAINTAINERS: Add maintainer for the slcan driver
MAINTAINERS | 6 +
drivers/net/can/slcan/slcan-core.c | 451 +++++++++--------------------
2 files changed, 139 insertions(+), 318 deletions(-)
--
2.32.0
In the driver there are parts of code where the prefix `slc' is used and
others where the prefix `slcan' is used instead. The patch replaces
every occurrence of `slc' with `slcan', except for the netdev functions
where, to avoid compilation conflicts, it was necessary to replace `slc'
with `slcan_netdev'.
The patch does not make any functional changes.
Signed-off-by: Dario Binacchi <[email protected]>
---
(no changes since v1)
drivers/net/can/slcan/slcan-core.c | 109 +++++++++++++++--------------
1 file changed, 56 insertions(+), 53 deletions(-)
diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index 2c546f4a7981..09d4abbbd9f4 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -63,16 +63,17 @@ MODULE_LICENSE("GPL");
MODULE_AUTHOR("Oliver Hartkopp <[email protected]>");
/* maximum rx buffer len: extended CAN frame with timestamp */
-#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r") + 1)
-
-#define SLC_CMD_LEN 1
-#define SLC_SFF_ID_LEN 3
-#define SLC_EFF_ID_LEN 8
-#define SLC_STATE_LEN 1
-#define SLC_STATE_BE_RXCNT_LEN 3
-#define SLC_STATE_BE_TXCNT_LEN 3
-#define SLC_STATE_FRAME_LEN (1 + SLC_CMD_LEN + SLC_STATE_BE_RXCNT_LEN + \
- SLC_STATE_BE_TXCNT_LEN)
+#define SLCAN_MTU (sizeof("T1111222281122334455667788EA5F\r") + 1)
+
+#define SLCAN_CMD_LEN 1
+#define SLCAN_SFF_ID_LEN 3
+#define SLCAN_EFF_ID_LEN 8
+#define SLCAN_STATE_LEN 1
+#define SLCAN_STATE_BE_RXCNT_LEN 3
+#define SLCAN_STATE_BE_TXCNT_LEN 3
+#define SLCAN_STATE_FRAME_LEN (1 + SLCAN_CMD_LEN + \
+ SLCAN_STATE_BE_RXCNT_LEN + \
+ SLCAN_STATE_BE_TXCNT_LEN)
struct slcan {
struct can_priv can;
@@ -83,9 +84,9 @@ struct slcan {
struct work_struct tx_work; /* Flushes transmit buffer */
/* These are pointers to the malloc()ed frame buffers. */
- unsigned char rbuff[SLC_MTU]; /* receiver buffer */
+ unsigned char rbuff[SLCAN_MTU]; /* receiver buffer */
int rcount; /* received chars counter */
- unsigned char xbuff[SLC_MTU]; /* transmitter buffer */
+ unsigned char xbuff[SLCAN_MTU]; /* transmitter buffer*/
unsigned char *xhead; /* pointer to next XMIT byte */
int xleft; /* bytes left in XMIT queue */
@@ -164,7 +165,7 @@ int slcan_enable_err_rst_on_open(struct net_device *ndev, bool on)
*************************************************************************/
/* Send one completely decapsulated can_frame to the network layer */
-static void slc_bump_frame(struct slcan *sl)
+static void slcan_bump_frame(struct slcan *sl)
{
struct sk_buff *skb;
struct can_frame *cf;
@@ -184,10 +185,10 @@ static void slc_bump_frame(struct slcan *sl)
fallthrough;
case 't':
/* store dlc ASCII value and terminate SFF CAN ID string */
- cf->len = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN];
- sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0;
+ cf->len = sl->rbuff[SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN];
+ sl->rbuff[SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN] = 0;
/* point to payload data behind the dlc */
- cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1;
+ cmd += SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN + 1;
break;
case 'R':
cf->can_id = CAN_RTR_FLAG;
@@ -195,16 +196,16 @@ static void slc_bump_frame(struct slcan *sl)
case 'T':
cf->can_id |= CAN_EFF_FLAG;
/* store dlc ASCII value and terminate EFF CAN ID string */
- cf->len = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN];
- sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0;
+ cf->len = sl->rbuff[SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN];
+ sl->rbuff[SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN] = 0;
/* point to payload data behind the dlc */
- cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1;
+ cmd += SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN + 1;
break;
default:
goto decode_failed;
}
- if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid))
+ if (kstrtou32(sl->rbuff + SLCAN_CMD_LEN, 16, &tmpid))
goto decode_failed;
cf->can_id |= tmpid;
@@ -251,7 +252,7 @@ static void slc_bump_frame(struct slcan *sl)
* sb256256 : state bus-off: rx counter 256, tx counter 256
* sa057033 : state active, rx counter 57, tx counter 33
*/
-static void slc_bump_state(struct slcan *sl)
+static void slcan_bump_state(struct slcan *sl)
{
struct net_device *dev = sl->dev;
struct sk_buff *skb;
@@ -277,16 +278,16 @@ static void slc_bump_state(struct slcan *sl)
return;
}
- if (state == sl->can.state || sl->rcount < SLC_STATE_FRAME_LEN)
+ if (state == sl->can.state || sl->rcount < SLCAN_STATE_FRAME_LEN)
return;
- cmd += SLC_STATE_BE_RXCNT_LEN + SLC_CMD_LEN + 1;
- cmd[SLC_STATE_BE_TXCNT_LEN] = 0;
+ cmd += SLCAN_STATE_BE_RXCNT_LEN + SLCAN_CMD_LEN + 1;
+ cmd[SLCAN_STATE_BE_TXCNT_LEN] = 0;
if (kstrtou32(cmd, 10, &txerr))
return;
*cmd = 0;
- cmd -= SLC_STATE_BE_RXCNT_LEN;
+ cmd -= SLCAN_STATE_BE_RXCNT_LEN;
if (kstrtou32(cmd, 10, &rxerr))
return;
@@ -314,7 +315,7 @@ static void slc_bump_state(struct slcan *sl)
* e1a : len 1, errors: ACK error
* e3bcO: len 3, errors: Bit0 error, CRC error, Tx overrun error
*/
-static void slc_bump_err(struct slcan *sl)
+static void slcan_bump_err(struct slcan *sl)
{
struct net_device *dev = sl->dev;
struct sk_buff *skb;
@@ -330,7 +331,7 @@ static void slc_bump_err(struct slcan *sl)
else
return;
- if ((len + SLC_CMD_LEN + 1) > sl->rcount)
+ if ((len + SLCAN_CMD_LEN + 1) > sl->rcount)
return;
skb = alloc_can_err_skb(dev, &cf);
@@ -338,7 +339,7 @@ static void slc_bump_err(struct slcan *sl)
if (skb)
cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
- cmd += SLC_CMD_LEN + 1;
+ cmd += SLCAN_CMD_LEN + 1;
for (i = 0; i < len; i++, cmd++) {
switch (*cmd) {
case 'a':
@@ -427,7 +428,7 @@ static void slc_bump_err(struct slcan *sl)
netif_rx(skb);
}
-static void slc_bump(struct slcan *sl)
+static void slcan_bump(struct slcan *sl)
{
switch (sl->rbuff[0]) {
case 'r':
@@ -437,11 +438,11 @@ static void slc_bump(struct slcan *sl)
case 'R':
fallthrough;
case 'T':
- return slc_bump_frame(sl);
+ return slcan_bump_frame(sl);
case 'e':
- return slc_bump_err(sl);
+ return slcan_bump_err(sl);
case 's':
- return slc_bump_state(sl);
+ return slcan_bump_state(sl);
default:
return;
}
@@ -453,12 +454,12 @@ static void slcan_unesc(struct slcan *sl, unsigned char s)
if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
sl->rcount > 4)
- slc_bump(sl);
+ slcan_bump(sl);
sl->rcount = 0;
} else {
if (!test_bit(SLF_ERROR, &sl->flags)) {
- if (sl->rcount < SLC_MTU) {
+ if (sl->rcount < SLCAN_MTU) {
sl->rbuff[sl->rcount++] = s;
return;
}
@@ -474,7 +475,7 @@ static void slcan_unesc(struct slcan *sl, unsigned char s)
*************************************************************************/
/* Encapsulate one can_frame and stuff into a TTY queue. */
-static void slc_encaps(struct slcan *sl, struct can_frame *cf)
+static void slcan_encaps(struct slcan *sl, struct can_frame *cf)
{
int actual, i;
unsigned char *pos;
@@ -491,11 +492,11 @@ static void slc_encaps(struct slcan *sl, struct can_frame *cf)
/* determine number of chars for the CAN-identifier */
if (cf->can_id & CAN_EFF_FLAG) {
id &= CAN_EFF_MASK;
- endpos = pos + SLC_EFF_ID_LEN;
+ endpos = pos + SLCAN_EFF_ID_LEN;
} else {
*pos |= 0x20; /* convert R/T to lower case for SFF */
id &= CAN_SFF_MASK;
- endpos = pos + SLC_SFF_ID_LEN;
+ endpos = pos + SLCAN_SFF_ID_LEN;
}
/* build 3 (SFF) or 8 (EFF) digit CAN identifier */
@@ -505,7 +506,8 @@ static void slc_encaps(struct slcan *sl, struct can_frame *cf)
id >>= 4;
}
- pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN;
+ pos += (cf->can_id & CAN_EFF_FLAG) ?
+ SLCAN_EFF_ID_LEN : SLCAN_SFF_ID_LEN;
*pos++ = cf->len + '0';
@@ -583,7 +585,8 @@ static void slcan_write_wakeup(struct tty_struct *tty)
}
/* Send a can_frame to a TTY queue. */
-static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
+static netdev_tx_t slcan_netdev_xmit(struct sk_buff *skb,
+ struct net_device *dev)
{
struct slcan *sl = netdev_priv(dev);
@@ -602,7 +605,7 @@ static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
}
netif_stop_queue(sl->dev);
- slc_encaps(sl, (struct can_frame *)skb->data); /* encaps & send */
+ slcan_encaps(sl, (struct can_frame *)skb->data); /* encaps & send */
spin_unlock(&sl->lock);
out:
@@ -645,7 +648,7 @@ static int slcan_transmit_cmd(struct slcan *sl, const unsigned char *cmd)
}
/* Netdevice UP -> DOWN routine */
-static int slc_close(struct net_device *dev)
+static int slcan_netdev_close(struct net_device *dev)
{
struct slcan *sl = netdev_priv(dev);
int err;
@@ -674,10 +677,10 @@ static int slc_close(struct net_device *dev)
}
/* Netdevice DOWN -> UP routine */
-static int slc_open(struct net_device *dev)
+static int slcan_netdev_open(struct net_device *dev)
{
struct slcan *sl = netdev_priv(dev);
- unsigned char cmd[SLC_MTU];
+ unsigned char cmd[SLCAN_MTU];
int err, s;
/* The baud rate is not set with the command
@@ -737,16 +740,16 @@ static int slc_open(struct net_device *dev)
return err;
}
-static int slcan_change_mtu(struct net_device *dev, int new_mtu)
+static int slcan_netdev_change_mtu(struct net_device *dev, int new_mtu)
{
return -EINVAL;
}
-static const struct net_device_ops slc_netdev_ops = {
- .ndo_open = slc_open,
- .ndo_stop = slc_close,
- .ndo_start_xmit = slc_xmit,
- .ndo_change_mtu = slcan_change_mtu,
+static const struct net_device_ops slcan_netdev_ops = {
+ .ndo_open = slcan_netdev_open,
+ .ndo_stop = slcan_netdev_close,
+ .ndo_start_xmit = slcan_netdev_xmit,
+ .ndo_change_mtu = slcan_netdev_change_mtu,
};
/******************************************
@@ -819,7 +822,7 @@ static int slcan_open(struct tty_struct *tty)
/* Configure netdev interface */
sl->dev = dev;
- dev->netdev_ops = &slc_netdev_ops;
+ dev->netdev_ops = &slcan_netdev_ops;
slcan_set_ethtool_ops(dev);
/* Mark ldisc channel as alive */
@@ -887,7 +890,7 @@ static int slcan_ioctl(struct tty_struct *tty, unsigned int cmd,
}
}
-static struct tty_ldisc_ops slc_ldisc = {
+static struct tty_ldisc_ops slcan_ldisc = {
.owner = THIS_MODULE,
.num = N_SLCAN,
.name = "slcan",
@@ -905,7 +908,7 @@ static int __init slcan_init(void)
pr_info("slcan: serial line CAN interface driver\n");
/* Fill in our line protocol discipline, and register it */
- status = tty_register_ldisc(&slc_ldisc);
+ status = tty_register_ldisc(&slcan_ldisc);
if (status)
pr_err("slcan: can't register line discipline\n");
@@ -917,7 +920,7 @@ static void __exit slcan_exit(void)
/* This will only be called when all channels have been closed by
* userspace - tty_ldisc.c takes care of the module's refcount.
*/
- tty_unregister_ldisc(&slc_ldisc);
+ tty_unregister_ldisc(&slcan_ldisc);
}
module_init(slcan_init);
--
2.32.0
Taking inspiration from the drivers/net/can/can327.c driver and at the
suggestion of its author Max Staudt, I removed legacy stuff like
`SLCAN_MAGIC' and `slcan_devs' resulting in simplification of the code
and its maintainability.
The use of slcan_devs is derived from a very old kernel, since slip.c
is about 30 years old, so today's kernel allows us to remove it.
The .hangup() ldisc function, which only called the ldisc .close(), has
been removed since the ldisc layer calls .close() in a good place
anyway.
The old slcanX name has been dropped in order to use the standard canX
interface naming. It has been assumed that this change does not break
the user space as the slcan driver provides an ioctl to resolve from tty
fd to netdev name.
The `maxdev' module parameter has also been removed.
CC: Max Staudt <[email protected]>
Signed-off-by: Dario Binacchi <[email protected]>
---
Changes in v2:
- Update the commit description.
- Drop the old "slcan" name to use the standard canX interface naming.
drivers/net/can/slcan/slcan-core.c | 318 ++++++-----------------------
1 file changed, 63 insertions(+), 255 deletions(-)
diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index c3dd7468a066..2c546f4a7981 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -1,11 +1,14 @@
/*
* slcan.c - serial line CAN interface driver (using tty line discipline)
*
- * This file is derived from linux/drivers/net/slip/slip.c
+ * This file is derived from linux/drivers/net/slip/slip.c and got
+ * inspiration from linux/drivers/net/can/can327.c for the rework made
+ * on the line discipline code.
*
* slip.c Authors : Laurence Culhane <[email protected]>
* Fred N. van Kempen <[email protected]>
* slcan.c Author : Oliver Hartkopp <[email protected]>
+ * can327.c Author : Max Staudt <[email protected]>
*
* 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
@@ -36,7 +39,6 @@
*/
#include <linux/module.h>
-#include <linux/moduleparam.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
@@ -46,7 +48,6 @@
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
-#include <linux/delay.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/workqueue.h>
@@ -61,15 +62,6 @@ MODULE_DESCRIPTION("serial line CAN interface");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Oliver Hartkopp <[email protected]>");
-#define SLCAN_MAGIC 0x53CA
-
-static int maxdev = 10; /* MAX number of SLCAN channels;
- * This can be overridden with
- * insmod slcan.ko maxdev=nnn
- */
-module_param(maxdev, int, 0);
-MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
-
/* maximum rx buffer len: extended CAN frame with timestamp */
#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r") + 1)
@@ -83,7 +75,6 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
SLC_STATE_BE_TXCNT_LEN)
struct slcan {
struct can_priv can;
- int magic;
/* Various fields. */
struct tty_struct *tty; /* ptr to TTY structure */
@@ -99,17 +90,14 @@ struct slcan {
int xleft; /* bytes left in XMIT queue */
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 */
+#define SLF_ERROR 0 /* Parity, etc. error */
+#define SLF_XCMD 1 /* Command transmission */
unsigned long cmd_flags; /* Command flags */
#define CF_ERR_RST 0 /* Reset errors on open */
wait_queue_head_t xcmd_wait; /* Wait queue for commands */
/* transmission */
};
-static struct net_device **slcan_devs;
-
static const u32 slcan_bitrate_const[] = {
10000, 20000, 50000, 100000, 125000,
250000, 500000, 800000, 1000000
@@ -553,9 +541,8 @@ 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 ||
- (unlikely(!netif_running(sl->dev)) &&
- likely(!test_bit(SLF_XCMD, &sl->flags)))) {
+ if (unlikely(!netif_running(sl->dev)) &&
+ likely(!test_bit(SLF_XCMD, &sl->flags))) {
spin_unlock_bh(&sl->lock);
return;
}
@@ -590,13 +577,9 @@ static void slcan_transmit(struct work_struct *work)
*/
static void slcan_write_wakeup(struct tty_struct *tty)
{
- struct slcan *sl;
+ struct slcan *sl = (struct slcan *)tty->disc_data;
- rcu_read_lock();
- sl = rcu_dereference(tty->disc_data);
- if (sl)
- schedule_work(&sl->tx_work);
- rcu_read_unlock();
+ schedule_work(&sl->tx_work);
}
/* Send a can_frame to a TTY queue. */
@@ -667,25 +650,21 @@ static int slc_close(struct net_device *dev)
struct slcan *sl = netdev_priv(dev);
int err;
- spin_lock_bh(&sl->lock);
- if (sl->tty) {
- if (sl->can.bittiming.bitrate &&
- sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) {
- spin_unlock_bh(&sl->lock);
- err = slcan_transmit_cmd(sl, "C\r");
- spin_lock_bh(&sl->lock);
- if (err)
- netdev_warn(dev,
- "failed to send close command 'C\\r'\n");
- }
-
- /* TTY discipline is running. */
- clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
+ if (sl->can.bittiming.bitrate &&
+ sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) {
+ err = slcan_transmit_cmd(sl, "C\r");
+ if (err)
+ netdev_warn(dev,
+ "failed to send close command 'C\\r'\n");
}
+
+ /* TTY discipline is running. */
+ clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
+ flush_work(&sl->tx_work);
+
netif_stop_queue(dev);
sl->rcount = 0;
sl->xleft = 0;
- spin_unlock_bh(&sl->lock);
close_candev(dev);
sl->can.state = CAN_STATE_STOPPED;
if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN)
@@ -701,9 +680,6 @@ static int slc_open(struct net_device *dev)
unsigned char cmd[SLC_MTU];
int err, s;
- if (!sl->tty)
- return -ENODEV;
-
/* The baud rate is not set with the command
* `ip link set <iface> type can bitrate <baud>' and therefore
* can.bittiming.bitrate is CAN_BITRATE_UNSET (0), causing
@@ -718,8 +694,6 @@ static int slc_open(struct net_device *dev)
return err;
}
- sl->flags &= BIT(SLF_INUSE);
-
if (sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) {
for (s = 0; s < ARRAY_SIZE(slcan_bitrate_const); s++) {
if (sl->can.bittiming.bitrate == slcan_bitrate_const[s])
@@ -763,14 +737,6 @@ static int slc_open(struct net_device *dev)
return err;
}
-static void slc_dealloc(struct slcan *sl)
-{
- int i = sl->dev->base_addr;
-
- free_candev(sl->dev);
- slcan_devs[i] = NULL;
-}
-
static int slcan_change_mtu(struct net_device *dev, int new_mtu)
{
return -EINVAL;
@@ -800,7 +766,7 @@ static void slcan_receive_buf(struct tty_struct *tty,
{
struct slcan *sl = (struct slcan *)tty->disc_data;
- if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
+ if (!netif_running(sl->dev))
return;
/* Read the characters out of the buffer */
@@ -815,80 +781,15 @@ static void slcan_receive_buf(struct tty_struct *tty,
}
}
-/************************************
- * slcan_open helper routines.
- ************************************/
-
-/* Collect hanged up channels */
-static void slc_sync(void)
-{
- int i;
- struct net_device *dev;
- struct slcan *sl;
-
- for (i = 0; i < maxdev; i++) {
- dev = slcan_devs[i];
- if (!dev)
- break;
-
- sl = netdev_priv(dev);
- if (sl->tty)
- continue;
- if (dev->flags & IFF_UP)
- dev_close(dev);
- }
-}
-
-/* Find a free SLCAN channel, and link in this `tty' line. */
-static struct slcan *slc_alloc(void)
-{
- int i;
- struct net_device *dev = NULL;
- struct slcan *sl;
-
- for (i = 0; i < maxdev; i++) {
- dev = slcan_devs[i];
- if (!dev)
- break;
- }
-
- /* Sorry, too many, all slots in use */
- if (i >= maxdev)
- return NULL;
-
- dev = alloc_candev(sizeof(*sl), 1);
- if (!dev)
- return NULL;
-
- snprintf(dev->name, sizeof(dev->name), "slcan%d", i);
- dev->netdev_ops = &slc_netdev_ops;
- dev->base_addr = i;
- slcan_set_ethtool_ops(dev);
- sl = netdev_priv(dev);
-
- /* Initialize channel control data */
- sl->magic = SLCAN_MAGIC;
- sl->dev = dev;
- sl->can.bitrate_const = slcan_bitrate_const;
- sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const);
- spin_lock_init(&sl->lock);
- INIT_WORK(&sl->tx_work, slcan_transmit);
- init_waitqueue_head(&sl->xcmd_wait);
- slcan_devs[i] = dev;
-
- return sl;
-}
-
/* Open the high-level part of the SLCAN channel.
* This function is called by the TTY module when the
- * SLCAN line discipline is called for. Because we are
- * sure the tty line exists, we only have to link it to
- * a free SLCAN channel...
+ * SLCAN line discipline is called for.
*
* Called in process context serialized from other ldisc calls.
*/
static int slcan_open(struct tty_struct *tty)
{
+ struct net_device *dev;
struct slcan *sl;
int err;
@@ -898,72 +799,49 @@ static int slcan_open(struct tty_struct *tty)
if (!tty->ops->write)
return -EOPNOTSUPP;
- /* RTnetlink lock is misused here to serialize concurrent
- * opens of slcan channels. There are better ways, but it is
- * the simplest one.
- */
- rtnl_lock();
+ dev = alloc_candev(sizeof(*sl), 1);
+ if (!dev)
+ return -ENFILE;
- /* Collect hanged up channels. */
- slc_sync();
+ sl = netdev_priv(dev);
- sl = tty->disc_data;
+ /* Configure TTY interface */
+ tty->receive_room = 65536; /* We don't flow control */
+ sl->rcount = 0;
+ sl->xleft = 0;
+ spin_lock_init(&sl->lock);
+ INIT_WORK(&sl->tx_work, slcan_transmit);
+ init_waitqueue_head(&sl->xcmd_wait);
- err = -EEXIST;
- /* First make sure we're not already connected. */
- if (sl && sl->magic == SLCAN_MAGIC)
- goto err_exit;
+ /* Configure CAN metadata */
+ sl->can.bitrate_const = slcan_bitrate_const;
+ sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const);
- /* OK. Find a free SLCAN channel to use. */
- err = -ENFILE;
- sl = slc_alloc();
- if (!sl)
- goto err_exit;
+ /* Configure netdev interface */
+ sl->dev = dev;
+ dev->netdev_ops = &slc_netdev_ops;
+ slcan_set_ethtool_ops(dev);
+ /* Mark ldisc channel as alive */
sl->tty = tty;
tty->disc_data = sl;
- if (!test_bit(SLF_INUSE, &sl->flags)) {
- /* Perform the low-level SLCAN initialization. */
- sl->rcount = 0;
- sl->xleft = 0;
-
- set_bit(SLF_INUSE, &sl->flags);
-
- rtnl_unlock();
- err = register_candev(sl->dev);
- if (err) {
- pr_err("slcan: can't register candev\n");
- goto err_free_chan;
- }
- } else {
- rtnl_unlock();
+ err = register_candev(dev);
+ if (err) {
+ free_candev(dev);
+ pr_err("slcan: can't register candev\n");
+ return err;
}
- tty->receive_room = 65536; /* We don't flow control */
-
+ netdev_info(dev, "slcan on %s.\n", tty->name);
/* TTY layer expects 0 on success */
return 0;
-
-err_free_chan:
- rtnl_lock();
- sl->tty = NULL;
- tty->disc_data = NULL;
- clear_bit(SLF_INUSE, &sl->flags);
- slc_dealloc(sl);
- rtnl_unlock();
- return err;
-
-err_exit:
- rtnl_unlock();
-
- /* Count references from TTY module */
- return err;
}
/* Close down a SLCAN channel.
* This means flushing out any pending queues, and then returning. This
* call is serialized against other ldisc functions.
+ * Once this is called, no other ldisc function of ours is entered.
*
* We also use this method for a hangup event.
*/
@@ -971,28 +849,20 @@ static void slcan_close(struct tty_struct *tty)
{
struct slcan *sl = (struct slcan *)tty->disc_data;
- /* First make sure we're connected. */
- if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
- return;
+ /* unregister_netdev() calls .ndo_stop() so we don't have to.
+ * Our .ndo_stop() also flushes the TTY write wakeup handler,
+ * so we can safely set sl->tty = NULL after this.
+ */
+ unregister_candev(sl->dev);
+ /* Mark channel as dead */
spin_lock_bh(&sl->lock);
- rcu_assign_pointer(tty->disc_data, NULL);
+ tty->disc_data = NULL;
sl->tty = NULL;
spin_unlock_bh(&sl->lock);
- synchronize_rcu();
- flush_work(&sl->tx_work);
-
- slc_close(sl->dev);
- unregister_candev(sl->dev);
- rtnl_lock();
- slc_dealloc(sl);
- rtnl_unlock();
-}
-
-static void slcan_hangup(struct tty_struct *tty)
-{
- slcan_close(tty);
+ netdev_info(sl->dev, "slcan off %s.\n", tty->name);
+ free_candev(sl->dev);
}
/* Perform I/O control on an active SLCAN channel. */
@@ -1002,10 +872,6 @@ static int slcan_ioctl(struct tty_struct *tty, unsigned int cmd,
struct slcan *sl = (struct slcan *)tty->disc_data;
unsigned int tmp;
- /* First make sure we're connected. */
- if (!sl || sl->magic != SLCAN_MAGIC)
- return -EINVAL;
-
switch (cmd) {
case SIOCGIFNAME:
tmp = strlen(sl->dev->name) + 1;
@@ -1027,7 +893,6 @@ static struct tty_ldisc_ops slc_ldisc = {
.name = "slcan",
.open = slcan_open,
.close = slcan_close,
- .hangup = slcan_hangup,
.ioctl = slcan_ioctl,
.receive_buf = slcan_receive_buf,
.write_wakeup = slcan_write_wakeup,
@@ -1037,78 +902,21 @@ static int __init slcan_init(void)
{
int status;
- if (maxdev < 4)
- maxdev = 4; /* Sanity */
-
pr_info("slcan: serial line CAN interface driver\n");
- pr_info("slcan: %d dynamic interface channels.\n", maxdev);
-
- slcan_devs = kcalloc(maxdev, sizeof(struct net_device *), GFP_KERNEL);
- if (!slcan_devs)
- return -ENOMEM;
/* Fill in our line protocol discipline, and register it */
status = tty_register_ldisc(&slc_ldisc);
- if (status) {
+ if (status)
pr_err("slcan: can't register line discipline\n");
- kfree(slcan_devs);
- }
+
return status;
}
static void __exit slcan_exit(void)
{
- int i;
- struct net_device *dev;
- struct slcan *sl;
- unsigned long timeout = jiffies + HZ;
- int busy = 0;
-
- if (!slcan_devs)
- return;
-
- /* First of all: check for active disciplines and hangup them.
- */
- do {
- if (busy)
- msleep_interruptible(100);
-
- busy = 0;
- for (i = 0; i < maxdev; i++) {
- dev = slcan_devs[i];
- if (!dev)
- continue;
- sl = netdev_priv(dev);
- spin_lock_bh(&sl->lock);
- if (sl->tty) {
- busy++;
- tty_hangup(sl->tty);
- }
- spin_unlock_bh(&sl->lock);
- }
- } while (busy && time_before(jiffies, timeout));
-
- /* FIXME: hangup is async so we should wait when doing this second
- * phase
+ /* This will only be called when all channels have been closed by
+ * userspace - tty_ldisc.c takes care of the module's refcount.
*/
-
- for (i = 0; i < maxdev; i++) {
- dev = slcan_devs[i];
- if (!dev)
- continue;
-
- sl = netdev_priv(dev);
- if (sl->tty)
- netdev_err(dev, "tty discipline still running\n");
-
- slc_close(dev);
- unregister_candev(dev);
- slc_dealloc(sl);
- }
-
- kfree(slcan_devs);
- slcan_devs = NULL;
-
tty_unregister_ldisc(&slc_ldisc);
}
--
2.32.0
At the suggestion of its author Oliver Hartkopp ([1]), I take over the
maintainer-ship and add myself to the authors of the driver.
[1] https://marc.info/?l=linux-can&m=165806705927851&w=2
Signed-off-by: Dario Binacchi <[email protected]>
---
Changes in v2:
- Add the patch "MAINTAINERS: Add myself as maintainer of the SLCAN driver"
to the series.
MAINTAINERS | 6 ++++++
drivers/net/can/slcan/slcan-core.c | 1 +
2 files changed, 7 insertions(+)
diff --git a/MAINTAINERS b/MAINTAINERS
index fc7d75c5cdb9..74e42f78e7cb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18448,6 +18448,12 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab.git
F: include/linux/sl?b*.h
F: mm/sl?b*
+SLCAN CAN NETWORK DRIVER
+M: Dario Binacchi <[email protected]>
+L: [email protected]
+S: Maintained
+F: drivers/net/can/slcan/
+
SLEEPABLE READ-COPY UPDATE (SRCU)
M: Lai Jiangshan <[email protected]>
M: "Paul E. McKenney" <[email protected]>
diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
index 76f20dc1aa90..54f16ebd72bc 100644
--- a/drivers/net/can/slcan/slcan-core.c
+++ b/drivers/net/can/slcan/slcan-core.c
@@ -61,6 +61,7 @@ MODULE_ALIAS_LDISC(N_SLCAN);
MODULE_DESCRIPTION("serial line CAN interface");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Oliver Hartkopp <[email protected]>");
+MODULE_AUTHOR("Dario Binacchi <[email protected]>");
/* maximum rx buffer len: extended CAN frame with timestamp */
#define SLCAN_MTU (sizeof("T1111222281122334455667788EA5F\r") + 1)
--
2.32.0
On 25.07.2022 08:54:15, Dario Binacchi wrote:
> Taking inspiration from the drivers/net/can/can327.c driver and at the
> suggestion of its author Max Staudt, I removed legacy stuff like
> `SLCAN_MAGIC' and `slcan_devs' resulting in simplification of the code
> and its maintainability.
>
> The use of slcan_devs is derived from a very old kernel, since slip.c
> is about 30 years old, so today's kernel allows us to remove it.
>
> The .hangup() ldisc function, which only called the ldisc .close(), has
> been removed since the ldisc layer calls .close() in a good place
> anyway.
>
> The old slcanX name has been dropped in order to use the standard canX
> interface naming. It has been assumed that this change does not break
> the user space as the slcan driver provides an ioctl to resolve from tty
> fd to netdev name.
Is there a man page that documents this iotcl? Please add it and/or the
IOCTL name.
> The `maxdev' module parameter has also been removed.
>
> CC: Max Staudt <[email protected]>
> Signed-off-by: Dario Binacchi <[email protected]>
>
> ---
>
> Changes in v2:
Nitpick:
Changes since RFC: https://lore.kernel.org/all/[email protected]
> - Update the commit description.
> - Drop the old "slcan" name to use the standard canX interface naming.
>
> drivers/net/can/slcan/slcan-core.c | 318 ++++++-----------------------
> 1 file changed, 63 insertions(+), 255 deletions(-)
>
> diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
> index c3dd7468a066..2c546f4a7981 100644
> --- a/drivers/net/can/slcan/slcan-core.c
> +++ b/drivers/net/can/slcan/slcan-core.c
[...]
> @@ -898,72 +799,49 @@ static int slcan_open(struct tty_struct *tty)
> if (!tty->ops->write)
> return -EOPNOTSUPP;
>
> - /* RTnetlink lock is misused here to serialize concurrent
> - * opens of slcan channels. There are better ways, but it is
> - * the simplest one.
> - */
> - rtnl_lock();
> + dev = alloc_candev(sizeof(*sl), 1);
> + if (!dev)
> + return -ENFILE;
>
> - /* Collect hanged up channels. */
> - slc_sync();
> + sl = netdev_priv(dev);
>
> - sl = tty->disc_data;
> + /* Configure TTY interface */
> + tty->receive_room = 65536; /* We don't flow control */
> + sl->rcount = 0;
> + sl->xleft = 0;
Nitpick: Please use 1 space in front of the =.
regards,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
On 25.07.2022 08:54:19, Dario Binacchi wrote:
> At the suggestion of its author Oliver Hartkopp ([1]), I take over the
> maintainer-ship and add myself to the authors of the driver.
>
> [1] https://marc.info/?l=linux-can&m=165806705927851&w=2
Please use the lore.k.o link:
https://lore.kernel.org/all/[email protected]
Suggested-by: Oliver Hartkopp <[email protected]>
> Signed-off-by: Dario Binacchi <[email protected]>
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
On 25.07.2022 08:54:13, Dario Binacchi wrote:
> With this series I try to finish the task, started with the series [1],
> of completely removing the dependency of the slcan driver from the
> userspace slcand/slcan_attach applications.
>
> The series, however, still lacks a patch for sending the bitrate setting
> command to the adapter:
>
> slcan_attach -b <btr> <dev>
>
> Without at least this patch the task cannot be considered truly completed.
>
> The idea I got is that this can only happen through the ethtool API.
> Among the various operations made available by this interface I would
> have used the set_regs (but only the get_regs has been developed), or,
> the set_eeprom, even if the setting would not be stored in an eeprom.
> IMHO it would take a set_regs operation with a `struct ethtool_wregs'
> parameter similar to `struct ethtool_eeprom' without the magic field:
This doesn't feel right.
> struct ethtool_wregs {
> __u32 cmd;
> __u32 offset;
> __u32 len;
> __u8 data[0];
> };
>
> But I am not the expert and if there was an alternative solution already
> usable, it would be welcome.
Have a look at the get/set_tunable() callback:
| https://elixir.bootlin.com/linux/latest/source/include/linux/ethtool.h#L575
You probably have to add a new tunable. Here you'll find the people and
commits that changed the tunable:
| https://github.com/torvalds/linux/blame/master/include/uapi/linux/ethtool.h#L229
It's usually worth including them in an RFC patch series where you add a
new tunable and make use of it in the slcan driver.
regards,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
Hello Marc,
On Mon, Jul 25, 2022 at 2:38 PM Marc Kleine-Budde <[email protected]> wrote:
>
> On 25.07.2022 08:54:15, Dario Binacchi wrote:
> > Taking inspiration from the drivers/net/can/can327.c driver and at the
> > suggestion of its author Max Staudt, I removed legacy stuff like
> > `SLCAN_MAGIC' and `slcan_devs' resulting in simplification of the code
> > and its maintainability.
> >
> > The use of slcan_devs is derived from a very old kernel, since slip.c
> > is about 30 years old, so today's kernel allows us to remove it.
> >
> > The .hangup() ldisc function, which only called the ldisc .close(), has
> > been removed since the ldisc layer calls .close() in a good place
> > anyway.
> >
> > The old slcanX name has been dropped in order to use the standard canX
> > interface naming. It has been assumed that this change does not break
> > the user space as the slcan driver provides an ioctl to resolve from tty
> > fd to netdev name.
>
> Is there a man page that documents this iotcl? Please add it and/or the
> IOCTL name.
I have not found documentation of the SIOCGIFNAME ioctl for the line discipline,
but only for netdev (i. e.
https://man7.org/linux/man-pages/man7/netdevice.7.html),
Thanks and regards,
Dario
>
> > The `maxdev' module parameter has also been removed.
> >
> > CC: Max Staudt <[email protected]>
> > Signed-off-by: Dario Binacchi <[email protected]>
> >
> > ---
> >
> > Changes in v2:
>
> Nitpick:
> Changes since RFC: https://lore.kernel.org/all/[email protected]
>
> > - Update the commit description.
> > - Drop the old "slcan" name to use the standard canX interface naming.
> >
> > drivers/net/can/slcan/slcan-core.c | 318 ++++++-----------------------
> > 1 file changed, 63 insertions(+), 255 deletions(-)
> >
> > diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c
> > index c3dd7468a066..2c546f4a7981 100644
> > --- a/drivers/net/can/slcan/slcan-core.c
> > +++ b/drivers/net/can/slcan/slcan-core.c
>
> [...]
>
> > @@ -898,72 +799,49 @@ static int slcan_open(struct tty_struct *tty)
> > if (!tty->ops->write)
> > return -EOPNOTSUPP;
> >
> > - /* RTnetlink lock is misused here to serialize concurrent
> > - * opens of slcan channels. There are better ways, but it is
> > - * the simplest one.
> > - */
> > - rtnl_lock();
> > + dev = alloc_candev(sizeof(*sl), 1);
> > + if (!dev)
> > + return -ENFILE;
> >
> > - /* Collect hanged up channels. */
> > - slc_sync();
> > + sl = netdev_priv(dev);
> >
> > - sl = tty->disc_data;
> > + /* Configure TTY interface */
> > + tty->receive_room = 65536; /* We don't flow control */
> > + sl->rcount = 0;
> > + sl->xleft = 0;
>
> Nitpick: Please use 1 space in front of the =.
>
> regards,
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Embedded Linux | https://www.pengutronix.de |
> Vertretung West/Dortmund | Phone: +49-231-2826-924 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
--
Dario Binacchi
Embedded Linux Developer
[email protected]
__________________________________
Amarula Solutions SRL
Via Le Canevare 30, 31100 Treviso, Veneto, IT
T. +39 042 243 5310
[email protected]
http://www.amarulasolutions.com
On 26.07.2022 12:11:33, Dario Binacchi wrote:
> Hello Marc,
>
> On Mon, Jul 25, 2022 at 2:38 PM Marc Kleine-Budde <[email protected]> wrote:
> >
> > On 25.07.2022 08:54:15, Dario Binacchi wrote:
> > > Taking inspiration from the drivers/net/can/can327.c driver and at the
> > > suggestion of its author Max Staudt, I removed legacy stuff like
> > > `SLCAN_MAGIC' and `slcan_devs' resulting in simplification of the code
> > > and its maintainability.
> > >
> > > The use of slcan_devs is derived from a very old kernel, since slip.c
> > > is about 30 years old, so today's kernel allows us to remove it.
> > >
> > > The .hangup() ldisc function, which only called the ldisc .close(), has
> > > been removed since the ldisc layer calls .close() in a good place
> > > anyway.
> > >
> > > The old slcanX name has been dropped in order to use the standard canX
> > > interface naming. It has been assumed that this change does not break
> > > the user space as the slcan driver provides an ioctl to resolve from tty
> > > fd to netdev name.
> >
> > Is there a man page that documents this iotcl? Please add it and/or the
> > IOCTL name.
>
> I have not found documentation of the SIOCGIFNAME ioctl for the line discipline,
> but only for netdev (i. e.
> https://man7.org/linux/man-pages/man7/netdevice.7.html),
Ok - What about:
The old slcanX name has been dropped in order to use the standard canX
interface naming. The ioctl SIOCGIFNAME can be used to query the name of
the created interface. Further There are several ways to get stable
interfaces names in user space, e.g. udev or systemd-networkd.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
On Tue, Jul 26, 2022 at 1:58 PM Marc Kleine-Budde <[email protected]> wrote:
>
> On 26.07.2022 12:11:33, Dario Binacchi wrote:
> > Hello Marc,
> >
> > On Mon, Jul 25, 2022 at 2:38 PM Marc Kleine-Budde <[email protected]> wrote:
> > >
> > > On 25.07.2022 08:54:15, Dario Binacchi wrote:
> > > > Taking inspiration from the drivers/net/can/can327.c driver and at the
> > > > suggestion of its author Max Staudt, I removed legacy stuff like
> > > > `SLCAN_MAGIC' and `slcan_devs' resulting in simplification of the code
> > > > and its maintainability.
> > > >
> > > > The use of slcan_devs is derived from a very old kernel, since slip.c
> > > > is about 30 years old, so today's kernel allows us to remove it.
> > > >
> > > > The .hangup() ldisc function, which only called the ldisc .close(), has
> > > > been removed since the ldisc layer calls .close() in a good place
> > > > anyway.
> > > >
> > > > The old slcanX name has been dropped in order to use the standard canX
> > > > interface naming. It has been assumed that this change does not break
> > > > the user space as the slcan driver provides an ioctl to resolve from tty
> > > > fd to netdev name.
> > >
> > > Is there a man page that documents this iotcl? Please add it and/or the
> > > IOCTL name.
> >
> > I have not found documentation of the SIOCGIFNAME ioctl for the line discipline,
> > but only for netdev (i. e.
> > https://man7.org/linux/man-pages/man7/netdevice.7.html),
>
> Ok - What about:
>
> The old slcanX name has been dropped in order to use the standard canX
> interface naming. The ioctl SIOCGIFNAME can be used to query the name of
> the created interface. Further There are several ways to get stable
> interfaces names in user space, e.g. udev or systemd-networkd.
Good! I will update the commit message in the next version I will submit.
Thanks and regards,
Dario
>
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Embedded Linux | https://www.pengutronix.de |
> Vertretung West/Dortmund | Phone: +49-231-2826-924 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
--
Dario Binacchi
Embedded Linux Developer
[email protected]
__________________________________
Amarula Solutions SRL
Via Le Canevare 30, 31100 Treviso, Veneto, IT
T. +39 042 243 5310
[email protected]
http://www.amarulasolutions.com
Hello Marc,
On Mon, Jul 25, 2022 at 3:25 PM Marc Kleine-Budde <[email protected]> wrote:
>
> On 25.07.2022 08:54:13, Dario Binacchi wrote:
> > With this series I try to finish the task, started with the series [1],
> > of completely removing the dependency of the slcan driver from the
> > userspace slcand/slcan_attach applications.
> >
> > The series, however, still lacks a patch for sending the bitrate setting
> > command to the adapter:
> >
> > slcan_attach -b <btr> <dev>
> >
> > Without at least this patch the task cannot be considered truly completed.
> >
> > The idea I got is that this can only happen through the ethtool API.
> > Among the various operations made available by this interface I would
> > have used the set_regs (but only the get_regs has been developed), or,
> > the set_eeprom, even if the setting would not be stored in an eeprom.
> > IMHO it would take a set_regs operation with a `struct ethtool_wregs'
> > parameter similar to `struct ethtool_eeprom' without the magic field:
>
> This doesn't feel right.
>
> > struct ethtool_wregs {
> > __u32 cmd;
> > __u32 offset;
> > __u32 len;
> > __u8 data[0];
> > };
> >
> > But I am not the expert and if there was an alternative solution already
> > usable, it would be welcome.
>
> Have a look at the get/set_tunable() callback:
>
> | https://elixir.bootlin.com/linux/latest/source/include/linux/ethtool.h#L575
>
> You probably have to add a new tunable. Here you'll find the people and
> commits that changed the tunable:
>
> | https://github.com/torvalds/linux/blame/master/include/uapi/linux/ethtool.h#L229
>
> It's usually worth including them in an RFC patch series where you add a
> new tunable and make use of it in the slcan driver.
Thank you very much for the suggestions.
Regards,
Dario
>
> regards,
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Embedded Linux | https://www.pengutronix.de |
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--
Dario Binacchi
Embedded Linux Developer
[email protected]
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