Date:	Thu, 06 Nov 2014 13:06:36 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Yijing Wang <wangyijing@...wei.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Grant Likely <grant.likely@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Alexander Gordeev <agordeev@...hat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [Patch Part2 v4 21/31] PCI/MSI: enhance PCI MSI core to support
 hierarchy irqdomain

On 2014/11/6 9:58, Yijing Wang wrote:
>>>  
>>> @@ -1098,3 +1099,128 @@ int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
>>>  	return nvec;
>>>  }
>>>  EXPORT_SYMBOL(pci_enable_msix_range);
>>> +
>>> +#ifdef	CONFIG_PCI_MSI_IRQ_DOMAIN
>>
>> Space, not tab.
>>
>>> +static inline irq_hw_number_t
>>> +msi_get_hwirq(struct pci_dev *pdev, struct msi_desc *msidesc)
>>
>> The convention in this file is "struct pci_dev *dev".  And "struct msi_desc
>> *desc" (or maybe "*entry").  Try to converge things, not diverge them.
>>
>>> +{
>>> +	return (irq_hw_number_t)msidesc->msi_attrib.entry_nr |
>>> +		PCI_DEVID(pdev->bus->number, pdev->devfn) << 11 |
>>> +		(pci_domain_nr(pdev->bus) & 0xFFFFFFFF) << 27;
>>
>> Where does this bit layout come from?  Is this defined in the spec
>> somewhere?  A reference would help.
> 
> Currently, more and more Non-PCI device use MSI(or similar MSI mechanism), like DMAR fault irq
> and HPET FSB irq. And we have to add additional code to support the MSI capability.
> So I hope we can decouple MSI code and PCI code, then we can unify all MSI(or Message Based interrupt)
> in one framework.
Hi Yijing,
	I have a following patch to share more code among MSI/DMAR/HPET,
which is one step forward as you suggested. Will send out that patch set
soon.
Regards!
Gerry

> 
> Thanks!
> Yijing.
> 
>>
>>> +}
>>> +
>>> +static int msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
>>> +			    unsigned int nr_irqs, void *arg)
>>> +{
>>> +	int i, ret;
>>> +	irq_hw_number_t hwirq = arch_msi_irq_domain_get_hwirq(arg);
>>> +
>>> +	if (irq_find_mapping(domain, hwirq) > 0)
>>> +		return -EEXIST;
>>> +
>>> +	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
>>> +	if (ret >= 0)
>>
>> 	if (ret < 0)
>> 		return ret;
>>
>> and un-indent the mainline code below.  Then it's obvious that this is the
>> normal case, not the error case.
>>
>>> +		for (i = 0; i < nr_irqs; i++) {
>>> +			irq_domain_set_hwirq_and_chip(domain, virq + i,
>>> +					hwirq + i, &msi_chip, (void *)(long)i);
>>> +			__irq_set_handler(virq + i, handle_edge_irq, 0, "edge");
>>> +		}
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static void msi_domain_free(struct irq_domain *domain, unsigned int virq,
>>> +			    unsigned int nr_irqs)
>>> +{
>>> +	int i;
>>> +
>>> +	for (i = 0; i < nr_irqs; i++) {
>>> +		struct msi_desc *msidesc = irq_get_msi_desc(virq);
>>> +
>>> +		if (msidesc)
>>> +			msidesc->irq = 0;
>>> +	}
>>> +	irq_domain_free_irqs_top(domain, virq, nr_irqs);
>>> +}
>>> +
>>> +static int msi_domain_activate(struct irq_domain *domain,
>>> +			       struct irq_data *irq_data)
>>> +{
>>> +	int ret = 0;
>>> +	struct msi_msg msg;
>>> +
>>> +	/*
>>> +	 * irq_data->chip_data is MSI/MSIx offset.
>>
>> "MSI-X", as you wrote on the next line.
>>
>>> +	 * MSI-X message is written per-IRQ, the offset is always 0.
>>> +	 * MSI message denotes a contiguous group of IRQs, written for 0th IRQ.
>>> +	 */
>>> +	if (!irq_data->chip_data) {
>>
>> 	if (irq_data->chip_data)
>> 		return 0;
>>
>> and un-indent the mainline code below, and drop the "ret = 0" init above.
>>
>>> +		ret = irq_chip_compose_msi_msg(irq_data, &msg);
>>> +		if (ret == 0)
>>
>> 	if (ret)
>> 		return ret;
>>
>>> +			write_msi_msg(irq_data->irq, &msg);
>>> +	}
>>> +
>>> +	return ret;
>> 	return 0;
>>> +}
>>> +
>>> +static int msi_domain_deactivate(struct irq_domain *domain,
>>> +				 struct irq_data *irq_data)
>>> +{
>>> +	struct msi_msg msg;
>>> +
>>> +	if (irq_data->chip_data) {
>>> +		memset(&msg, 0, sizeof(msg));
>>> +		write_msi_msg(irq_data->irq, &msg);
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static struct irq_domain_ops msi_domain_ops = {
>>> +	.alloc = msi_domain_alloc,
>>> +	.free = msi_domain_free,
>>> +	.activate = msi_domain_activate,
>>> +	.deactivate = msi_domain_deactivate,
>>> +};
>>> +
>>> +struct irq_domain *msi_create_irq_domain(struct irq_domain *parent)
>>> +{
>>> +	struct irq_domain *domain;
>>> +
>>> +	domain = irq_domain_add_tree(NULL, &msi_domain_ops, NULL);
>>> +	if (domain)
>>
>> 	if (!domain)
>> 		return NULL;
>>
>> and un-indent this:
>>
>>> +		domain->parent = parent;
>>> +
>>> +	return domain;
>>> +}
>>> +
>>> +int msi_irq_domain_alloc_irqs(struct irq_domain *domain, int type,
>>> +			      struct pci_dev *dev, void *arg)
>>> +{
>>> +	int i, virq;
>>> +	struct msi_desc *msidesc;
>>> +	int node = dev_to_node(&dev->dev);
>>> +
>>> +	list_for_each_entry(msidesc, &dev->msi_list, list) {
>>> +		arch_msi_irq_domain_set_hwirq(arg, msi_get_hwirq(dev, msidesc));
>>> +		virq = irq_domain_alloc_irqs(domain, msidesc->nvec_used,
>>> +					     node, arg);
>>> +		if (virq < 0) {
>>> +			/* Special handling for pci_enable_msi_range(). */
>>> +			return (type == PCI_CAP_ID_MSI &&
>>> +				msidesc->nvec_used > 1) ?  1 : -ENOSPC;	
>>
>> I think "if" would be easier to read than this ternary expression.
>>
>>> +		}
>>> +		for (i = 0; i < msidesc->nvec_used; i++)
>>> +			irq_set_msi_desc_off(virq + i, i, msidesc);
>>> +	}
>>> +
>>> +	list_for_each_entry(msidesc, &dev->msi_list, list)
>>> +		if (msidesc->nvec_used == 1)
>>> +			dev_dbg(&dev->dev, "irq %d for MSI/MSI-X\n", virq);
>>> +		else
>>> +			dev_dbg(&dev->dev, "irq [%d-%d] for MSI/MSI-X\n",
>>> +				virq, virq + msidesc->nvec_used - 1);
>>> +
>>> +	return 0;
>>> +}
>>> +#endif	/* CONFIG_PCI_MSI_IRQ_DOMAIN */
>>> diff --git a/include/linux/msi.h b/include/linux/msi.h
>>> index 44f4746d033b..05dcd425f82b 100644
>>> --- a/include/linux/msi.h
>>> +++ b/include/linux/msi.h
>>> @@ -75,4 +75,15 @@ struct msi_chip {
>>>  	void (*teardown_irq)(struct msi_chip *chip, unsigned int irq);
>>>  };
>>>  
>>> +#ifdef	CONFIG_PCI_MSI_IRQ_DOMAIN
>>
>> Use a space here, not a tab.
>>
>>> +extern struct irq_chip msi_chip;
>>
>> I don't think "msi_chip" is a good name.  "Chip" only hints that it's a
>> semiconductor integrated circuit; it doesn't say anything about what it
>> does.  I've suggested "msi_controller" elsewhere.
>>
>> Why does this need to be exported?  And why should there be only one in a
>> system?
>>
>>> +extern struct irq_domain *msi_create_irq_domain(struct irq_domain *parent);
>>> +extern int msi_irq_domain_alloc_irqs(struct irq_domain *domain, int type,
>>> +				     struct pci_dev *dev, void *arg);
>>> +
>>> +extern irq_hw_number_t arch_msi_irq_domain_get_hwirq(void *arg);
>>> +extern void arch_msi_irq_domain_set_hwirq(void *arg, irq_hw_number_t hwirq);
>>
>> Look at the rest of the file and notice that the existing code does not use
>> "extern" on function declarations.
>>
>>> +#endif	/* CONFIG_PCI_MSI_IRQ_DOMAIN */
>>
>> Use a space here (not a tab), like the #endif just below.
>>
>>>  #endif /* LINUX_MSI_H */
>>> -- 
>>> 1.7.10.4
>>>
>>
>> .
>>
> 
> 
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