Subject: [Patch Part2 v4 21/31] PCI/MSI: enhance PCI MSI core to support hierarchy irqdomain

From: [email-masked] (Yijing Wang)
Date: Thu, 6 Nov 2014 09:58:11 +0800

>>  
>> @@ -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.

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
>>
> 
> .
> 

-- 
Thanks!
Yijing