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

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Date:	Wed, 13 Aug 2014 09:16:46 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	Bjorn Helgaas <bhelgaas@...gle.com>,
	<linux-kernel@...r.kernel.org>, Xinwei Hu <huxinwei@...wei.com>,
	Wuyun <wuyun.wu@...wei.com>, <linux-pci@...r.kernel.org>,
	Marc Zyngier <marc.zyngier@....com>,
	<linux-arm-kernel@...ts.infradead.org>,
	Russell King <linux@....linux.org.uk>,
	<arnab.basu@...escale.com>, <x86@...nel.org>,
	"Arnd Bergmann" <arnd@...db.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, <xen-devel@...ts.xenproject.org>,
	Joerg Roedel <joro@...tes.org>,
	<iommu@...ts.linux-foundation.org>, <linux-mips@...ux-mips.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	<linuxppc-dev@...ts.ozlabs.org>, <linux-s390@...r.kernel.org>,
	Sebastian Ott <sebott@...ux.vnet.ibm.com>,
	"Tony Luck" <tony.luck@...el.com>, <linux-ia64@...r.kernel.org>,
	"David S. Miller" <davem@...emloft.net>,
	<sparclinux@...r.kernel.org>, Chris Metcalf <cmetcalf@...era.com>
Subject: Re: [RFC PATCH 07/20] x86/MSI: Use msi_chip instead of arch func
 to configure MSI/MSI-X

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@...wei.com>
>> ---
>>  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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