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can: peak_usb: export PCAN CAN channel ID as sysfs device attribute 

This patch exports the CAN channel ID as a sysfs attribute. The CAN
channel ID is a user-configurable u8/u32 identifier that can be set
individually for each CAN interface of a PEAK USB device.

Exporting the channel ID as a sysfs attribute allows users to easily read
the ID and to write udev rules that can match against the ID. This is
especially useful for PEAK USB devices that do not export a serial
number at SUB level.

Signed-off-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Lukas Magel <lukas.magel@posteo.net>
Link: https://lore.kernel.org/all/20230116200932.157769-7-lukas.magel@posteo.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Lukas Magel 2023-01-16 20:09:30 +00:00 committed by Marc Kleine-Budde
parent 36d007c6fc
commit 6d02f6daeb
2 changed files with 44 additions and 0 deletions
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19
Documentation/ABI/testing/sysfs-class-net-peak_usb Normal file
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@ -0,0 +1,19 @@
What: /sys/class/net/<iface>/peak_usb/can_channel_id
Date: November 2022
KernelVersion: 6.2
Contact: Stephane Grosjean <s.grosjean@peak-system.com>
Description:
PEAK PCAN-USB devices support user-configurable CAN channel
identifiers. Contrary to a USB serial number, these identifiers
are writable and can be set per CAN interface. This means that
if a USB device exports multiple CAN interfaces, each of them
can be assigned a unique channel ID.
This attribute provides read-only access to the currently
configured value of the channel identifier. Depending on the
device type, the identifier has a length of 8 or 32 bit. The
value read from this attribute is always an 8 digit 32 bit
hexadecimal value in big endian format. If the device only
supports an 8 bit identifier, the upper 24 bit of the value are
set to zero.

25
drivers/net/can/usb/peak_usb/pcan_usb_core.c
View File

@ -15,6 +15,8 @@
#include <linux/netdevice.h>
#include <linux/usb.h>
#include <linux/ethtool.h>
#include <linux/sysfs.h>
#include <linux/device.h>
#include <linux/can.h>
#include <linux/can/dev.h>
@ -53,6 +55,26 @@ static const struct usb_device_id peak_usb_table[] = {
MODULE_DEVICE_TABLE(usb, peak_usb_table);
static ssize_t can_channel_id_show(struct device *dev, struct device_attribute *attr, char *buf)
{
struct net_device *netdev = to_net_dev(dev);
struct peak_usb_device *peak_dev = netdev_priv(netdev);
return sysfs_emit(buf, "%08X\n", peak_dev->can_channel_id);
}
static DEVICE_ATTR_RO(can_channel_id);
/* mutable to avoid cast in attribute_group */
static struct attribute *peak_usb_sysfs_attrs[] = {
&dev_attr_can_channel_id.attr,
NULL,
};
static const struct attribute_group peak_usb_sysfs_group = {
.name = "peak_usb",
.attrs = peak_usb_sysfs_attrs,
};
/*
* dump memory
*/
@ -961,6 +983,9 @@ static int peak_usb_create_dev(const struct peak_usb_adapter *peak_usb_adapter,
/* add ethtool support */
netdev->ethtool_ops = peak_usb_adapter->ethtool_ops;
/* register peak_usb sysfs files */
netdev->sysfs_groups[0] = &peak_usb_sysfs_group;
init_usb_anchor(&dev->rx_submitted);
init_usb_anchor(&dev->tx_submitted);