Messages in this thread | | | Subject | Re: [PATCH v8 5/8] genirq/irq: introduce msi_doorbell_info | From | Marc Zyngier <> | Date | Wed, 4 May 2016 13:57:30 +0100 |
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On 28/04/16 09:22, Eric Auger wrote: > The purpose is to be able to retrieve the MSI doorbells of an irqchip. > This is now needed since on some platforms those doorbells must be > iommu mapped (in case the MSIs transit through an IOMMU that do not > bypass those transactions). > > The assumption is there is a maximum of one doorbell region per cpu. > > A doorbell region is characterized by its physical address base, size and > IOMMU protection flag. Those 2 last characteristics are shared among all > doorbells. > > irq_chip msi_doorbell_info callback enables to retrieve the doorbells of > the irqchip. > > Signed-off-by: Eric Auger <eric.auger@linaro.org> > > --- > v7 -> v8: > - size and prot now are shared among all doorbells > - doorbells now directly points to a percpu phys_addr_t > > v7: creation > --- > include/linux/irq.h | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > diff --git a/include/linux/irq.h b/include/linux/irq.h > index c4de623..5dbb26d 100644 > --- a/include/linux/irq.h > +++ b/include/linux/irq.h > @@ -312,6 +312,19 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d) > return d->hwirq; > } > > +/* > + * Describe all the MSI doorbell regions for an irqchip. > + * A single doorbell region per cpu is assumed. > + * In case a single doorbell is supported for the whole irqchip, > + * the region is described in as cpu #0's one > + */ > +struct irq_chip_msi_doorbell_info { > + phys_addr_t __percpu *percpu_doorbells; /* per cpu base address */
Here's an idea: you could turn this field into a union:
union { phys_addr_t __percpu *percpu_doorbells; phys_addr_t global_doorbell; };
> + size_t size; /* size of a each doorbell */ > + int prot; /* iommu protection flag */ > + int nb_doorbells;
And this can be turned into a boolean:
bool doorbell_is_percpu;
This allows you to avoid allocating a bunch of percpu doorbells for a MSI controller that only has a global one. And the number of doorbells is always either 1 or the number of CPUs anyway.
Thanks,
M. -- Jazz is not dead. It just smells funny...
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