Re: [PATCH v2 8/8] PCI/MSI: Allow the MSI domain to be device-specific

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Oct 06, 2015 at 06:04:03PM +0100, Marc Zyngier wrote:
> So far, we've always considered that for a given PCI device, its
> MSI controller was either set by the architecture-specific
> pcibios hook, or simply inherited from the host bridge.
> 
> This doesn't cover things like firmware-defined topologies like
> msi-map (DT) or IORT (ACPI), which can provide information about
> which MSI controller to use on a per-device basis.
> 
> This patch adds the necessary hook into the MSI code to allow this
> feature, and provides the msi-map functionnality as a first
> implementation.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

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

I assume somebody other than me will merge this series.

> ---
>  drivers/pci/msi.c   | 17 +++++++++++++++++
>  drivers/pci/probe.c |  8 ++++++++
>  include/linux/msi.h |  6 ++++++
>  3 files changed, 31 insertions(+)
> 
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 81a2798..3daff31 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -1357,4 +1357,21 @@ u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev)
>  
>  	return rid;
>  }
> +
> +/**
> + * pci_msi_get_device_domain - Get the MSI domain for a given PCI device
> + * @pdev:	The PCI device
> + *
> + * Use the firmware data to find a device-specific MSI domain
> + * (i.e. not one that is ste as a default).
> + *
> + * Returns: The coresponding MSI domain or NULL if none has been found.
> + */
> +struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
> +{
> +	u32 rid = 0;
> +
> +	pci_for_each_dma_alias(pdev, get_msi_id_cb, &rid);
> +	return of_msi_map_get_device_domain(&pdev->dev, rid);
> +}
>  #endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index 7c333f8..f14a970 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -1639,6 +1639,14 @@ static struct irq_domain *pci_dev_msi_domain(struct pci_dev *dev)
>  	if (d)
>  		return d;
>  
> +	/*
> +	 * Let's see if we have a firmware interface able to provide
> +	 * the domain.
> +	 */
> +	d = pci_msi_get_device_domain(dev);
> +	if (d)
> +		return d;
> +
>  	return NULL;
>  }
>  
> diff --git a/include/linux/msi.h b/include/linux/msi.h
> index 56e3b76..375be7c 100644
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -294,6 +294,12 @@ irq_hw_number_t pci_msi_domain_calc_hwirq(struct pci_dev *dev,
>  int pci_msi_domain_check_cap(struct irq_domain *domain,
>  			     struct msi_domain_info *info, struct device *dev);
>  u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev);
> +struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev);
> +#else
> +static inline struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
> +{
> +	return NULL;
> +}
>  #endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */
>  
>  #endif /* LINUX_MSI_H */
> -- 
> 2.1.4
> 
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