Hello!
> This patch adds a function to output the link status of the CXL1.1 device
> when it is connected.
>
> In CXL1.1, the link status of the device is included in the RCRB mapped to
> the memory mapped register area. The value of that register is outputted
> to sysfs, and based on that, displays the link status information.
> diff --git a/lib/access.c b/lib/access.c
> index 7d66123..bc75a84 100644
> --- a/lib/access.c
> +++ b/lib/access.c
[...]
> @@ -268,3 +269,31 @@ pci_get_string_property(struct pci_dev *d, u32 prop)
>
> return NULL;
> }
> +
> +#define OBJNAMELEN 1024
> +#define OBJBUFSIZE 64
> +int
> +get_rcd_sysfs_obj_file(struct pci_dev *d, char *object, char *result)
> +{
> +#ifdef PCI_HAVE_PM_LINUX_SYSFS
> + char namebuf[OBJNAMELEN];
> + int n = snprintf(namebuf, OBJNAMELEN, "%s/devices/%04x:%02x:%02x.%d/%s",
> + pci_get_param(d->access, "sysfs.path"),
> + d->domain, d->bus, d->dev, d->func, object);
> + if (n < 0 || n >= OBJNAMELEN){
> + d->access->error("Failed to get filename");
> + return -1;
> + }
> + int fd = open(namebuf, O_RDONLY);
> + if(fd < 0)
> + return -1;
> + n = read(fd, result, OBJBUFSIZE);
> + if (n < 0 || n >= OBJBUFSIZE){
> + d->access->error("Failed to read the file");
> + return -1;
> + }
> + return 0;
> +#else
> + return -1;
> +#endif
> +}
This really is not the right place to read from sysfs. The libpci should provide
a backend-indepenent interface for reading this information and the sysfs
back-end (lib/sysfs.c) should provide one implementation of this interface.
I think that we can easily extend pci_fill_info() and add another PCI_FILL_xxx
flag for CXL RCD properties, which will be available in struct pci_dev (beware
that new fields have to be added _after_ all public fields to keep ABI compatibility).
> @@ -1445,6 +1515,9 @@ cap_express(struct device *d, int where, int cap)
> cap_express_dev(d, where, type);
> if (link)
> cap_express_link(d, where, type);
> + else if (type == PCI_EXP_TYPE_ROOT_INT_EP)
> + cap_express_link_rcd(d);
> +
> if (slot)
> cap_express_slot(d, where);
> if (type == PCI_EXP_TYPE_ROOT_PORT || type == PCI_EXP_TYPE_ROOT_EC)
Does it make sense to look up CXL RCD information for all PCIe devices of type
PCI_EXP_TYPE_ROOT_INT_EP? Shouldn't it be done only for devices with the CXL
capability?
Have a nice fortnight
--
Martin `MJ' Mareš <mj@xxxxxx> http://mj.ucw.cz/
United Computer Wizards, Prague, Czech Republic, Europe, Earth, Universe
