Hi Lukas,
Welcome on the linux-can mailing list!
On Mon. 1 août 2022 at 17:13, Lukas Magel <lukas.magel@xxxxxxxxxx> wrote:
> Peak USB devices support a configurable u8 / u32 device ID. In
> multi-device setups, this device ID can be configured and used to
> identify individual CAN interfaces independent of the order in which
> they are plugged into the system. At the current time, the device ID
> is already queried from the device and stored in the peak_usb_device
> struct.
>
> This patch exports the device ID (called device_number in the struct)
> as a sysfs attribute. The attribute name was chosen to be device_id
> instead of device_number because the latter has been deprecated by Peak
> in their API.
>
> Signed-off-by: Lukas Magel <lukas.magel@xxxxxxxxxx>
> Reviewed-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
For the public record, I did the review in private message.
> ---
> For the moment, the patch only implements read support for the device
> ID. My next goal is to also implement write access. However, this
> will require a more significant modification of the driver since the
> corresponding commands for ID retrieval and configuration are not
> implemented for all device types.
>
> drivers/net/can/usb/peak_usb/pcan_usb_core.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_core.c b/drivers/net/can/usb/peak_usb/pcan_usb_core.c
> index 27b0a72fd885..43df178e9473 100644
> --- a/drivers/net/can/usb/peak_usb/pcan_usb_core.c
> +++ b/drivers/net/can/usb/peak_usb/pcan_usb_core.c
> @@ -15,6 +15,8 @@
> #include <linux/netdevice.h>
> #include <linux/usb.h>
> #include <linux/ethtool.h>
> +#include <linux/device.h>
> +#include <linux/sysfs.h>
>
> #include <linux/can.h>
> #include <linux/can/dev.h>
> @@ -53,6 +55,15 @@ static const struct usb_device_id peak_usb_table[] = {
>
> MODULE_DEVICE_TABLE(usb, peak_usb_table);
>
> +static ssize_t device_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->device_number);
> +}
> +static DEVICE_ATTR_RO(device_id);
> +
> /*
> * dump memory
> */
> @@ -887,6 +898,11 @@ static int peak_usb_create_dev(const struct peak_usb_adapter *peak_usb_adapter,
> netdev_info(netdev, "attached to %s channel %u (device %u)\n",
> peak_usb_adapter->name, ctrl_idx, dev->device_number);
>
> + err = device_create_file(&netdev->dev, &dev_attr_device_id);
> + /* Do not error out since device was configured successfully */
> + if (err)
> + netdev_warn(netdev, "unable to expose device_id via sysfs %d\n", err);
netdev_warn(netdev, "unable to expose device_id via sysfs %pe\n", ERR_PTR(err));
I forgot this point in my first review. The %pe will print the
mnemotechnic instead of the error number. c.f.:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=57f5677e535ba24b8926a7125be2ef8d7f09323c
> +
> return 0;
>
> adap_dev_free:
> @@ -923,6 +939,8 @@ static void peak_usb_disconnect(struct usb_interface *intf)
> dev->state &= ~PCAN_USB_STATE_CONNECTED;
> strlcpy(name, netdev->name, IFNAMSIZ);
>
> + device_remove_file(&netdev->dev, &dev_attr_device_id);
> +
> unregister_netdev(netdev);
>
> kfree(dev->cmd_buf);
> --
> 2.37.1
>
