Re: [PATCH 4/5] PCI: add pci_irq_type() to query the allocated interrupt type

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Aug 11, 2026 at 12:47:43AM +0200, Danilo Krummrich wrote:
> Add a helper that returns PCI_IRQ_MSIX, PCI_IRQ_MSI, or PCI_IRQ_INTX
> based on the interrupt type the PCI core selected after
> pci_alloc_irq_vectors().
> 
> Several drivers already open-code this check against pdev->msix_enabled
> and pdev->msi_enabled, or even open code this helper [1].
> 
> A common helper avoids the duplication and keeps drivers from accessing
> the bitfield directly (see also [2]).
> 
> Link: https://elixir.bootlin.com/linux/v7.1/source/drivers/net/ethernet/aquantia/atlantic/aq_pci_func.c#L196 [1]
> Inspired-by: John Hubbard <jhubbard@nvidia.com>
> Link: https://lore.kernel.org/all/DKKG2QM3YJYB.Z2H2B2UXJ75N@kernel.org/ [2]
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>

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

In the subject line, to match drivers/pci/ history,

  PCI: Add pci_irq_type() ...

> ---
>  include/linux/pci.h | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 64b308b6e61c..80b8561b5be0 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1783,6 +1783,26 @@ void pci_free_irq_vectors(struct pci_dev *dev);
>  int pci_irq_vector(struct pci_dev *dev, unsigned int nr);
>  const struct cpumask *pci_irq_get_affinity(struct pci_dev *pdev, int vec);
>  
> +/**
> + * pci_irq_type - Get the interrupt type of a PCI device
> + * @pdev: the PCI device to operate on
> + *
> + * Discriminate the interrupt type the PCI core selected for this device
> + * after a successful pci_alloc_irq_vectors() call.
> + *
> + * Return: %PCI_IRQ_MSIX, %PCI_IRQ_MSI, or %PCI_IRQ_INTX.
> + */
> +static inline unsigned int pci_irq_type(struct pci_dev *pdev)
> +{
> +	if (pdev->msix_enabled)
> +		return PCI_IRQ_MSIX;
> +
> +	if (pdev->msi_enabled)
> +		return PCI_IRQ_MSI;
> +
> +	return PCI_IRQ_INTX;
> +}
> +
>  #else
>  static inline int pci_msi_vec_count(struct pci_dev *dev) { return -ENOSYS; }
>  static inline void pci_disable_msi(struct pci_dev *dev) { }
> @@ -1845,6 +1865,11 @@ static inline const struct cpumask *pci_irq_get_affinity(struct pci_dev *pdev,
>  {
>  	return cpu_possible_mask;
>  }
> +
> +static inline unsigned int pci_irq_type(struct pci_dev *pdev)
> +{
> +	return PCI_IRQ_INTX;
> +}
>  #endif
>  
>  /**
> -- 
> 2.55.0
>