Hi Marc,
On 04/20/2016 11:16 AM, Marc Zyngier wrote:
> On 19/04/16 18:13, 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.
>> The number of doorbells for the whole irqchip is stored in nb_doorbells.
>>
>> A doorbell region is characterized by its physical address base, size and
>> IOMMU protection flag.
>>
>> irq_chip msi_doorbell_info callback enables to retrieve the doorbells of
>> the irqchip.
>>
>> Signed-off-by: Eric Auger <eric.au...@linaro.org>
>>
>> ---
>>
>> v7: creation
>> ---
>> include/linux/irq.h | 26 ++++++++++++++++++++++----
>> 1 file changed, 22 insertions(+), 4 deletions(-)
>>
>> diff --git a/include/linux/irq.h b/include/linux/irq.h
>> index c4de623..fdad8c1 100644
>> --- a/include/linux/irq.h
>> +++ b/include/linux/irq.h
>> @@ -312,9 +312,25 @@ static inline irq_hw_number_t irqd_to_hwirq(struct
>> irq_data *d)
>> return d->hwirq;
>> }
>>
>> -/**
>> - * struct irq_chip - hardware interrupt chip descriptor
>> - *
>> +/* MSI doorbell region */
>> +struct irq_chip_msi_doorbell {
>> + phys_addr_t base;
>> + size_t size;
>> + int prot; /* iommu protection flag */
>
> I find this one a bit scary. "int" is a probably not the right type if
> it is a set of flags (it should describe both the protection and the
> memory attributes - in this case, probably something like Device +
> Writeable). You should probably use the same type the IOMMU code uses
> (and if it is actually an int, then I'll shut up...).
Hum yes iommu also uses an int ;-)
>
>> +};
>> +
>> +/*
>> + * 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 {
>> + struct irq_chip_msi_doorbell __percpu *percpu_doorbells;
>> + int nb_doorbells; /* overall number of doorbells */
>> +};
>
> How can size and prot be different from one CPU to another? It really
> feels like they should be common. Can I suggest something like this?
>
> struct irq_chip_msi_doorbell_info {
> phys_addr_t __percpu *doorbells;
> size_t size;
> u32 prot;
> };
>
> and get rid of struct irq_chip_msi_doorbell altogether?
I'am definitively fine with your proposal.
Thanks
Eric
>
>> +
>> +/** * struct irq_chip - hardware interrupt chip descriptor *
>> * @name: name for /proc/interrupts
>> * @irq_startup: start up the interrupt (defaults to ->enable if NULL)
>> * @irq_shutdown: shut down the interrupt (defaults to ->disable if NULL)
>> @@ -349,6 +365,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct
>> irq_data *d)
>> * @irq_get_irqchip_state: return the internal state of an interrupt
>> * @irq_set_irqchip_state: set the internal state of a interrupt
>> * @irq_set_vcpu_affinity: optional to target a vCPU in a virtual machine
>> + * @msi_doorbell_info: return the MSI doorbell info
>> * @ipi_send_single: send a single IPI to destination cpus
>> * @ipi_send_mask: send an IPI to destination cpus in cpumask
>> * @flags: chip specific flags
>> @@ -394,7 +411,8 @@ struct irq_chip {
>> int (*irq_set_irqchip_state)(struct irq_data *data, enum
>> irqchip_irq_state which, bool state);
>>
>> int (*irq_set_vcpu_affinity)(struct irq_data *data, void
>> *vcpu_info);
>> -
>> + const struct irq_chip_msi_doorbell_info *(*msi_doorbell_info)(
>> + struct irq_data *data);
>> void (*ipi_send_single)(struct irq_data *data, unsigned int
>> cpu);
>> void (*ipi_send_mask)(struct irq_data *data, const struct
>> cpumask *dest);
>>
>>
>
> Thanks,
>
> M.
>
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