On Thu, Jan 07, 2021 at 10:26:12AM +0100, Greg KH wrote:
> On Thu, Jan 07, 2021 at 02:07:08PM +0800, Xu Yilun wrote:
> > This driver supports the ethernet retimers (C827) for the Intel PAC
> > (Programmable Acceleration Card) N3000, which is a FPGA based Smart NIC.
> >
> > C827 is an Intel(R) Ethernet serdes transceiver chip that supports
> > up to 100G transfer. On Intel PAC N3000 there are 2 C827 chips
> > managed by the Intel MAX 10 BMC firmware. They are configured in 4 ports
> > 10G/25G retimer mode. Host could query their link states and firmware
> > version information via retimer interfaces (Shared registers) on Intel
> > MAX 10 BMC. The driver creates sysfs interfaces for users to query these
> > information.
>
> Networking people, please look at this sysfs file:
>
> > +What:
> > /sys/bus/platform/devices/n3000bmc-retimer.*.auto/link_statusX
> > +Date: Jan 2021
> > +KernelVersion: 5.12
> > +Contact: Xu Yilun <yilun...@intel.com>
> > +Description: Read only. Returns the status of each line side link.
> > "1" for
> > + link up, "0" for link down.
> > + Format: "%u".
>
> as I need your approval to add it because it is not the "normal" way for
> link status to be exported to userspace.
>
> One code issue:
>
> > +#define to_link_attr(dev_attr) \
> > + container_of(dev_attr, struct link_attr, attr)
> > +
> > +static ssize_t
> > +link_status_show(struct device *dev, struct device_attribute *attr, char
> > *buf)
> > +{
> > + struct m10bmc_retimer *retimer = dev_get_drvdata(dev);
> > + struct link_attr *lattr = to_link_attr(attr);
> > + unsigned int val;
> > + int ret;
> > +
> > + ret = m10bmc_sys_read(retimer->m10bmc, M10BMC_PKVL_LSTATUS, &val);
> > + if (ret)
> > + return ret;
> > +
> > + return sysfs_emit(buf, "%u\n",
> > + !!(val & BIT((retimer->id << 2) + lattr->index)));
> > +}
> > +
> > +#define link_status_attr(_index) \
> > + static struct link_attr link_attr_status##_index = \
> > + { .attr = __ATTR(link_status##_index, 0444, \
> > + link_status_show, NULL), \
> > + .index = (_index) }
>
> Why is this a "raw" attribute and not a device attribute?
It is actually a device_attribute. The device_attribute is embedded in
link_attr, like:
struct link_attr {
struct device_attribute attr;
u32 index;
};
An index for the link is appended along with the device_attribute, so we
could identify which link is being queried on link_status_show(). There
are 4 links and this is to avoid duplicated code like
link_status_1_show(), link_status_2_show() ...
>
> Please just use a normal DEVICE_ATTR_RO() macro to make it simpler and
DEVICE_ATTR_RO() is to define a standalone device_attribute variable, but
here we are initializing a field in struct link_attr.
Thanks,
Yilun
> easier to understand over time, what you are doing here. I can't
> determine what is happening with this code now...
>
> thanks,
>
> greg k-h
