Re: [PATCH v6 2/5] PCI/TPH: expose enabled requester type and capability helpers

Re: [PATCH v6 2/5] PCI/TPH: expose enabled requester type and capability helpers

[Bjorn Helgaas]

On Mon, Jun 08, 2026 at 11:56:39AM -0700, Zhiping Zhang wrote:
> Add pcie_tph_enabled_req_type() so drivers can query the enabled TPH
> requester mode without reaching into pci_dev internals, and
> pcie_tph_supported() so they can test whether the device exposes the
> PCIe TPH Extended Capability without doing the same.

s/exposes/advertises/

> This keeps pci_dev::tph_req_type and pci_dev::tph_cap inside the
> PCI/TPH code and provides !CONFIG_PCIE_TPH stubs for callers.

Update subject line to match capitalization of history
(use "git log --oneline drivers/pci/tph.c")

s/expose/Add/ in subject.

("Expose" suggests that the interfaces already exist and we're just
exporting them, but these interfaces didn't exist at all before.)

> Signed-off-by: Zhiping Zhang <zhipingz@meta.com>

With the above,

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/pci/tph.c       | 25 +++++++++++++++++++++++++
>  include/linux/pci-tph.h |  7 +++++++
>  2 files changed, 32 insertions(+)
> 
> diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c
> index 91145e8d9d95..aa09113c46d4 100644
> --- a/drivers/pci/tph.c
> +++ b/drivers/pci/tph.c
> @@ -174,6 +174,31 @@ u32 pcie_tph_get_st_table_loc(struct pci_dev *pdev)
>  }
>  EXPORT_SYMBOL(pcie_tph_get_st_table_loc);
>  
> +/**
> + * pcie_tph_enabled_req_type - Return the device's enabled TPH requester type
> + * @pdev: PCI device to query
> + *
> + * Return: PCI_TPH_REQ_DISABLE, PCI_TPH_REQ_TPH_ONLY or PCI_TPH_REQ_EXT_TPH.
> + */
> +u8 pcie_tph_enabled_req_type(struct pci_dev *pdev)
> +{
> +	return pdev->tph_req_type;
> +}
> +EXPORT_SYMBOL(pcie_tph_enabled_req_type);
> +
> +/**
> + * pcie_tph_supported - Whether the device advertises the TPH Extended Cap
> + * @pdev: PCI device to query
> + *
> + * Return: true when the device exposes the PCIe TPH Extended Capability,
> + * false otherwise.
> + */
> +bool pcie_tph_supported(struct pci_dev *pdev)
> +{
> +	return pdev->tph_cap != 0;
> +}
> +EXPORT_SYMBOL(pcie_tph_supported);
> +
>  /*
>   * Return the size of ST table. If ST table is not in TPH Requester Extended
>   * Capability space, return 0. Otherwise return the ST Table Size + 1.
> diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h
> index be68cd17f2f8..2e07bce77038 100644
> --- a/include/linux/pci-tph.h
> +++ b/include/linux/pci-tph.h
> @@ -9,6 +9,8 @@
>  #ifndef LINUX_PCI_TPH_H
>  #define LINUX_PCI_TPH_H
>  
> +#include <linux/pci_regs.h>
> +
>  /*
>   * According to the ECN for PCI Firmware Spec, Steering Tag can be different
>   * depending on the memory type: Volatile Memory or Persistent Memory. When a
> @@ -30,6 +32,8 @@ void pcie_disable_tph(struct pci_dev *pdev);
>  int pcie_enable_tph(struct pci_dev *pdev, int mode);
>  u16 pcie_tph_get_st_table_size(struct pci_dev *pdev);
>  u32 pcie_tph_get_st_table_loc(struct pci_dev *pdev);
> +u8 pcie_tph_enabled_req_type(struct pci_dev *pdev);
> +bool pcie_tph_supported(struct pci_dev *pdev);
>  #else
>  static inline int pcie_tph_set_st_entry(struct pci_dev *pdev,
>  					unsigned int index, u16 tag)
> @@ -41,6 +45,9 @@ static inline int pcie_tph_get_cpu_st(struct pci_dev *dev,
>  static inline void pcie_disable_tph(struct pci_dev *pdev) { }
>  static inline int pcie_enable_tph(struct pci_dev *pdev, int mode)
>  { return -EINVAL; }
> +static inline u8 pcie_tph_enabled_req_type(struct pci_dev *pdev)
> +{ return PCI_TPH_REQ_DISABLE; }
> +static inline bool pcie_tph_supported(struct pci_dev *pdev) { return false; }
>  #endif
>  
>  #endif /* LINUX_PCI_TPH_H */
> -- 
> 2.53.0-Meta
>