Re: [PATCH v6 2/3] PCI: cadence: Add HPA IP debugfs for LTSSM status

[Hans Zhang]

On 5/20/26 15:26, Aksh Garg wrote:
> On 19/05/26 18:06, Hans Zhang wrote:
> > Add debugfs support for HPA-based Cadence PCIe controllers. A new file
> > 'ltssm_status' is created under debugfs, allowing users to read the
> > current LTSSM state as a string and raw value.
> >
> > Signed-off-by: Hans Zhang <18255117159@xxxxxxx>
> > ---
> >   Documentation/ABI/testing/debugfs-cdns-pcie   |   5 +
> >   drivers/pci/controller/cadence/Kconfig        |   9 +
> >   drivers/pci/controller/cadence/Makefile       |   1 +
> >   drivers/pci/controller/cadence/pci-sky1.c     |   4 +
> >   .../controller/cadence/pcie-cadence-debugfs.c | 208 ++++++++++++++++++
> >   .../cadence/pcie-cadence-host-hpa.c           |  19 +-
> >   drivers/pci/controller/cadence/pcie-cadence.h | 153 +++++++++++++
> >   7 files changed, 398 insertions(+), 1 deletion(-)
> >   create mode 100644 Documentation/ABI/testing/debugfs-cdns-pcie
> >   create mode 100644 drivers/pci/controller/cadence/pcie-cadence- 
> > debugfs.c
> >
> > diff --git a/Documentation/ABI/testing/debugfs-cdns-pcie b/ 
> > Documentation/ABI/testing/debugfs-cdns-pcie
> > new file mode 100644
> > index 000000000000..c1104e28e4ee
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/debugfs-cdns-pcie
> > @@ -0,0 +1,5 @@
> > +What:        /sys/kernel/debug/cdns_pcie_<dev>/ltssm_status
> > +Date:        March 2026
> > +Contact:    Hans Zhang <18255117159@xxxxxxx>
> > +Description:    (RO) Read will return the current PCIe LTSSM state in 
> > both
> > +        string and raw value.
> > \ No newline at end of file
> > diff --git a/drivers/pci/controller/cadence/Kconfig b/drivers/pci/ 
> > controller/cadence/Kconfig
> > index 9e651d545973..cb010bc97aad 100644
> > --- a/drivers/pci/controller/cadence/Kconfig
> > +++ b/drivers/pci/controller/cadence/Kconfig
> > @@ -6,6 +6,15 @@ menu "Cadence-based PCIe controllers"
> >   config PCIE_CADENCE
> >       tristate
> > +config PCIE_CADENCE_DEBUGFS
> > +    tristate "Cadence PCIe debugfs entries"
> > +    depends on DEBUG_FS
> > +    depends on PCIE_CADENCE_HOST || PCIE_CADENCE_EP
> > +    help
> > +      Say Y here to enable debugfs entries for the PCIe controller. 
> > These
> > +      entries provide various debug features related to the 
> > controller and
> > +      the LTSSM status of link can be displayed.
> > +
> >   config PCIE_CADENCE_HOST
> >       tristate
> >       depends on OF
>
> Sashiko pointed the compilation issues when this is build as a module.
> The linkage issue needs to be resolved if we want this as a module.
> Also, if we build it as m, it would requires MODULE_LICENSE() and 
> MODULE_DESCRIPTION().

Hi Aksh,

Will add.


> > diff --git a/drivers/pci/controller/cadence/Makefile b/drivers/pci/ 
> > controller/cadence/Makefile
> > index b8ec1cecfaa8..2cdc4617e0c2 100644
> > --- a/drivers/pci/controller/cadence/Makefile
> > +++ b/drivers/pci/controller/cadence/Makefile
> > @@ -4,6 +4,7 @@ pcie-cadence-host-mod-y := pcie-cadence-host-common.o 
> > pcie-cadence-host.o pcie-c
> >   pcie-cadence-ep-mod-y := pcie-cadence-ep.o
> >   obj-$(CONFIG_PCIE_CADENCE) = pcie-cadence-mod.o
> > +obj-$(CONFIG_PCIE_CADENCE_DEBUGFS) += pcie-cadence-debugfs.o
> >   obj-$(CONFIG_PCIE_CADENCE_HOST) += pcie-cadence-host-mod.o
> >   obj-$(CONFIG_PCIE_CADENCE_EP) += pcie-cadence-ep-mod.o
> >   obj-$(CONFIG_PCIE_CADENCE_PLAT) += pcie-cadence-plat.o
> > diff --git a/drivers/pci/controller/cadence/pci-sky1.c b/drivers/pci/ 
> > controller/cadence/pci-sky1.c
> > index e1f4a98e2ab6..b8632f1d3156 100644
> > --- a/drivers/pci/controller/cadence/pci-sky1.c
> > +++ b/drivers/pci/controller/cadence/pci-sky1.c
> > @@ -221,6 +221,10 @@ MODULE_DEVICE_TABLE(of, of_sky1_pcie_match);
>
> [ ... ]
>
> >   /**
> > @@ -447,6 +583,7 @@ void cdns_pcie_host_disable(struct cdns_pcie_rc *rc);
> >   void __iomem *cdns_pci_map_bus(struct pci_bus *bus, unsigned int devfn,
> >                      int where);
> >   int cdns_pcie_hpa_host_setup(struct cdns_pcie_rc *rc);
> > +void cdns_pcie_hpa_host_disable(struct cdns_pcie_rc *rc);
> >   #else
> >   static inline int cdns_pcie_host_link_setup(struct cdns_pcie_rc *rc)
> >   {
> > @@ -472,6 +609,10 @@ static inline void cdns_pcie_host_disable(struct 
> > cdns_pcie_rc *rc)
> >   {
> >   }
> > +static inline void cdns_pcie_hpa_host_disable(struct cdns_pcie_rc *rc)
> > +{
> > +}
> > +
> >   static inline void __iomem *cdns_pci_map_bus(struct pci_bus *bus, 
> > unsigned int devfn,
> >                            int where)
> >   {
> > @@ -535,4 +676,16 @@ bool cdns_pcie_hpa_link_up(struct cdns_pcie *pcie);
> >   extern const struct dev_pm_ops cdns_pcie_pm_ops;
> > +#ifdef CONFIG_PCIE_CADENCE_DEBUGFS
>
> Use "#if IS_ENABLED(CONFIG_PCIE_CADENCE_DEBUGFS)" to resolve the 
> compilation error when building as a module.

Will change.

Best regards,
Hans

> > +void cdns_pcie_debugfs_deinit(struct cdns_pcie *pci);
> > +void cdns_pcie_debugfs_init(struct cdns_pcie *pci);
> > +#else
> > +static inline void cdns_pcie_debugfs_deinit(struct cdns_pcie *pci)
> > +{
> > +}
> > +static inline void cdns_pcie_debugfs_init(struct cdns_pcie *pci)
> > +{
> > +}
> > +#endif
> > +
> >   #endif /* _PCIE_CADENCE_H */