Re: [PATCH v5 1/5] acpi: pci: Setup MSI domain for ACPI based pci devices

[Marc Zyngier <marc.zyngier@arm.com>]

On Tue, 8 Dec 2015 17:48:02 -0800
Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com> wrote:

> This patch introduces pci_msi_register_fwnode_provider() for irqchip
> to register a callback, to provide a way to determine appropriate MSI
> domain for a pci device.
> 
> It also introduces pci_host_bridge_acpi_msi_domain(), which returns
> the MSI domain of the specified PCI host bridge with DOMAIN_BUS_PCI_MSI
> bus token. Then, it is assigned to pci device.
> 
> Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
> ---
>  drivers/pci/pci-acpi.c    | 32 ++++++++++++++++++++++++++++++++
>  drivers/pci/probe.c       |  2 ++
>  include/linux/irqdomain.h |  5 +++++
>  include/linux/pci.h       | 10 ++++++++++
>  4 files changed, 49 insertions(+)
> 
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index a32ba75..a555d7e 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -9,7 +9,9 @@
>  
>  #include <linux/delay.h>
>  #include <linux/init.h>
> +#include <linux/irqdomain.h>
>  #include <linux/pci.h>
> +#include <linux/msi.h>
>  #include <linux/pci_hotplug.h>
>  #include <linux/module.h>
>  #include <linux/pci-aspm.h>
> @@ -689,6 +691,36 @@ static struct acpi_bus_type acpi_pci_bus = {
>  	.cleanup = pci_acpi_cleanup,
>  };
>  
> +
> +static struct fwnode_handle *(*pci_msi_get_fwnode_cb)(struct device *dev);
> +
> +/**
> + * pci_msi_register_fwnode_provider - Register callback to retrieve fwnode
> + * @fn:		The interrupt domain to retrieve

This is the wrong description. Maybe something like@

  * @fn: Callback matching a device to a fwnode that identifies a PCI
    MSI domain

Or something along those lines.

> + *
> + * This should be called by irqchip driver, which is the parent of
> + * the MSI domain to provide callback interface to query fwnode.
> + */
> +void
> +pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *))
> +{
> +	pci_msi_get_fwnode_cb = fn;
> +}
> +
> +struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus)
> +{

Documentation?

> +	struct irq_domain *dom = NULL;
> +	struct fwnode_handle *fwnode = NULL;
> +
> +	if (pci_msi_get_fwnode_cb)
> +		fwnode = pci_msi_get_fwnode_cb(&bus->dev);
> +
> +	if (fwnode)
> +		dom = irq_find_matching_fwnode(fwnode,
> +					       DOMAIN_BUS_PCI_MSI);
> +	return dom;
> +}
> +

Suggestion:

	struct fwnode_handle *fwnode;

	if (!pci_msi_get_fwnode_cb)
		return NULL;

	fwnode = pci_msi_get_fwnode_cb(&bus->dev);
	if (!fwnode)
		return NULL;

	return irq_find_matching_fwnode(...);

My own personal taste, though.

>  static int __init acpi_pci_init(void)
>  {
>  	int ret;
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index edb1984..553a029 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -672,6 +672,8 @@ static struct irq_domain *pci_host_bridge_msi_domain(struct pci_bus *bus)
>  	 * should be called from here.
>  	 */
>  	d = pci_host_bridge_of_msi_domain(bus);
> +	if (!d)
> +		d = pci_host_bridge_acpi_msi_domain(bus);
>  
>  	return d;
>  }
> diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
> index d5e5c5b..a06feda 100644
> --- a/include/linux/irqdomain.h
> +++ b/include/linux/irqdomain.h
> @@ -410,6 +410,11 @@ static inline bool irq_domain_is_hierarchy(struct irq_domain *domain)
>  static inline void irq_dispose_mapping(unsigned int virq) { }
>  static inline void irq_domain_activate_irq(struct irq_data *data) { }
>  static inline void irq_domain_deactivate_irq(struct irq_data *data) { }
> +static inline struct irq_domain *irq_find_matching_fwnode(
> +	struct fwnode_handle *fwnode, enum irq_domain_bus_token bus_token)
> +{
> +	return NULL;
> +}
>  #endif /* !CONFIG_IRQ_DOMAIN */
>  
>  #endif /* _LINUX_IRQDOMAIN_H */
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 6ae25aa..d86378c 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1946,6 +1946,16 @@ static inline struct irq_domain *
>  pci_host_bridge_of_msi_domain(struct pci_bus *bus) { return NULL; }
>  #endif  /* CONFIG_OF */
>  
> +#ifdef CONFIG_ACPI
> +struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus);
> +
> +void
> +pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *));
> +#else
> +static inline struct irq_domain *
> +pci_host_bridge_acpi_msi_domain(struct pci_bus *bus) { return NULL; }
> +#endif
> +
>  #ifdef CONFIG_EEH
>  static inline struct eeh_dev *pci_dev_to_eeh_dev(struct pci_dev *pdev)
>  {

Other than the couple of nits above:

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>

	M.
-- 
Without deviation from the norm, progress is not possible.