Re: [Xen-devel] [RFC PATCH 07/20] x86/MSI: Use msi_chip instead of arch func to configure MSI/MSI-X

[Yijing Wang <wangyijing@xxxxxxxxxx>]

On 2014/8/13 3:09, Konrad Rzeszutek Wilk wrote:
> On Tue, Aug 12, 2014 at 03:26:00PM +0800, Yijing Wang wrote:
>> Introduce a new struct msi_chip apic_msi_chip instead of weak arch
>> functions to configure MSI/MSI-X in x86.
> 
> Why not 'x86_msi_ops' (see  arch/x86/kernel/x86_init.c)

Hi Konrad, I think currently lots of weak arch functions make MSI code
complex, we have following weak arch functions

arch_setup_msi_irqs
arch_setup_msi_irq
arch_msi_check_device
arch_teardown_msi_irqs
arch_teardown_msi_irq
arch_restore_msi_irqs
arch_msi_mask_irq
arch_msix_mask_irq

And Thierry Reding and Thomas Petazzoni introduce a new MSI chip infrastructure 
which
is used in arm platform now. Use msi_chip let us focus on implementing msi_chip 
ops functions(no need to implement all),
but now, we should know much of MSI enable flow, then override the weak 
functions.
I think use the unified MSI framework in all platforms is better.
Also this series is preparation to support Non-PCI MSI device use common MSI 
framework in linux. Non-PCI MSI devices
include hpet, dmar and the coming consolidator(introduced in ARM GICv3 spec, 
which is similar to MSI relay device).


Thanks!
Yijing.

>>
>> Signed-off-by: Yijing Wang <wangyijing@xxxxxxxxxx>
>> ---
>>  arch/x86/include/asm/pci.h     |    1 +
>>  arch/x86/kernel/apic/io_apic.c |   20 ++++++++++++++++----
>>  2 files changed, 17 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
>> index 0892ea0..878a06d 100644
>> --- a/arch/x86/include/asm/pci.h
>> +++ b/arch/x86/include/asm/pci.h
>> @@ -101,6 +101,7 @@ void native_teardown_msi_irq(unsigned int irq);
>>  void native_restore_msi_irqs(struct pci_dev *dev);
>>  int setup_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc,
>>                unsigned int irq_base, unsigned int irq_offset);
>> +extern struct msi_chip *x86_msi_chip;
>>  #else
>>  #define native_setup_msi_irqs               NULL
>>  #define native_teardown_msi_irq             NULL
>> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
>> index 2609dcd..eb8ab7c 100644
>> --- a/arch/x86/kernel/apic/io_apic.c
>> +++ b/arch/x86/kernel/apic/io_apic.c
>> @@ -3077,24 +3077,25 @@ int setup_msi_irq(struct pci_dev *dev, struct 
>> msi_desc *msidesc,
>>      return 0;
>>  }
>>  
>> -int native_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
>> +int native_setup_msi_irqs(struct device *dev, int nvec, int type)
>>  {
>>      struct msi_desc *msidesc;
>>      unsigned int irq;
>>      int node, ret;
>> +    struct pci_dev *pdev = to_pci_dev(dev);
>>  
>>      /* Multiple MSI vectors only supported with interrupt remapping */
>>      if (type == PCI_CAP_ID_MSI && nvec > 1)
>>              return 1;
>>  
>> -    node = dev_to_node(&dev->dev);
>> +    node = dev_to_node(dev);
>>  
>> -    list_for_each_entry(msidesc, &dev->msi_list, list) {
>> +    list_for_each_entry(msidesc, &pdev->msi_list, list) {
>>              irq = irq_alloc_hwirq(node);
>>              if (!irq)
>>                      return -ENOSPC;
>>  
>> -            ret = setup_msi_irq(dev, msidesc, irq, 0);
>> +            ret = setup_msi_irq(pdev, msidesc, irq, 0);
>>              if (ret < 0) {
>>                      irq_free_hwirq(irq);
>>                      return ret;
>> @@ -3214,6 +3215,17 @@ int default_setup_hpet_msi(unsigned int irq, unsigned 
>> int id)
>>  }
>>  #endif
>>  
>> +struct msi_chip apic_msi_chip = {
>> +    .setup_irqs = native_setup_msi_irqs,
>> +    .teardown_irq = native_teardown_msi_irq,
>> +};
>> +
>> +struct msi_chip *arch_get_match_msi_chip(struct device *dev)
>> +{
>> +    return x86_msi_chip;
>> +}
>> +
>> +struct msi_chip *x86_msi_chip = &apic_msi_chip;
>>  #endif /* CONFIG_PCI_MSI */
>>  /*
>>   * Hypertransport interrupt support
>> -- 
>> 1.7.1
>>
> 
> .
> 


-- 
Thanks!
Yijing


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