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SubjectRe: [PATCH -v2 1/3] PCI: introduce PCIe Device Serial Number Capability support
On 07/11/2013 05:43 AM, Yijing Wang wrote:
> Introduce PCIe Ext Capability Device Serial Number support,
> so we can use the unique device serial number to identify
> the physical device. During system suspend, if the PCIe
> device was removed and inserted a new same device, after
> system resume there is no good way to identify it, maybe
> Device Serial Number is a good choice if device support.
>
> Signed-off-by: Yijing Wang<wangyijing@huawei.com>
> ---
> drivers/pci/pci.c | 27 +++++++++++++++++++++++++++
> drivers/pci/probe.c | 2 ++
> include/linux/pci.h | 3 +++
> 3 files changed, 32 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e37fea6..2e855b5 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2048,6 +2048,33 @@ void pci_free_cap_save_buffers(struct pci_dev *dev)
> }
>
> /**
> + * pci_device_serial_number - get device serial number
> + * @dev: the PCI device
> + *
> + * return the device serial number if device support,
> + * otherwise return 0.
> + */
> +u64 pci_device_serial_number(struct pci_dev *dev)
See comment below:
void pci_device_serial_number(struct pci_dev *dev)

> +{
> + int pos;
> + u64 sn;
> + u32 lo, hi;
> +
> + if (!pci_is_pcie(dev))
> + return 0;
> +
See comment below:
if (!pci_is_pcie(dev)) {
dev->sn = 0;
return;
}
> + pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_DSN);
> + if (!pos)
> + return 0;
> +
> + pci_read_config_dword(dev, pos + 4,&lo);
> + pci_read_config_dword(dev, pos + 8,&hi);
> + sn = ((u64)hi<< 32) | lo;
See comment below:
dev->sn = ((u64)hi<< 32) | lo;
return;
> + return sn;
> +}
> +EXPORT_SYMBOL(pci_device_serial_number);
> +
> +/**
> * pci_configure_ari - enable or disable ARI forwarding
> * @dev: the PCI device
> *
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 46ada5c..c4c1a2b 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1322,6 +1322,8 @@ static void pci_init_capabilities(struct pci_dev *dev)
> /* Power Management */
> pci_pm_init(dev);
>
> + dev->sn = pci_device_serial_number(dev);
> +
Finally, 'the comment below':
I know you were following Bjorn's suggestion, which I thought
was an improvement, but why not do above assignment in pci_device_serial_number() ?
See above....
- Don

> /* Vital Product Data */
> pci_vpd_pci22_init(dev);
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 0fd1f15..10d190b 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -342,6 +342,7 @@ struct pci_dev {
> struct list_head msi_list;
> struct kset *msi_kset;
> #endif
> + u64 sn; /* device serieal number, 0 if not support */
> struct pci_vpd *vpd;
> #ifdef CONFIG_PCI_ATS
> union {
> @@ -995,6 +996,8 @@ ssize_t pci_read_vpd(struct pci_dev *dev, loff_t pos, size_t count, void *buf);
> ssize_t pci_write_vpd(struct pci_dev *dev, loff_t pos, size_t count, const void *buf);
> int pci_vpd_truncate(struct pci_dev *dev, size_t size);
>
> +u64 pci_device_serial_number(struct pci_dev *dev);
> +
> /* Helper functions for low-level code (drivers/pci/setup-[bus,res].c) */
> resource_size_t pcibios_retrieve_fw_addr(struct pci_dev *dev, int idx);
> void pci_bus_assign_resources(const struct pci_bus *bus);



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