linux-kernel - Re: [Patch V1 6/6] PCI, MSI: Provide mechanism to alloc/free MSI/MSIX interrupt from irqdomain

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Message-ID: <54650A79.1020408@arm.com>
Date:	Thu, 13 Nov 2014 19:46:01 +0000
From:	Marc Zyngier <marc.zyngier@....com>
To:	Jiang Liu <jiang.liu@...ux.intel.com>
CC:	Bjorn Helgaas <bhelgaas@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	Yijing Wang <wangyijing@...wei.com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Alexander Gordeev <agordeev@...hat.com>,
	Tony Luck <tony.luck@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [Patch V1 6/6] PCI, MSI: Provide mechanism to alloc/free MSI/MSIX
 interrupt from irqdomain

Hi Jiang,

On 13/11/14 11:43, Jiang Liu wrote:
> Provide mechanism to directly alloc/free MSI/MSIX interrupt from
> irqdomain, which will be used to replace arch_setup_msi_irq()/
> arch_setup_msi_irqs()/arch_teardown_msi_irq()/arch_teardown_msi_irqs().
> 
> To kill weak functions, this patch introduce a new weak function
> arch_get_pci_msi_domain(), which is to retrieve the MSI irqdomain
> for a PCI device. This weak function could be killed once we get
> a common way to associate MSI domain with PCI device.
> 
> Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
> ---
>  drivers/pci/msi.c   |   60 +++++++++++++++++++++++++++++++++++++++++++++++----
>  include/linux/msi.h |    3 +++
>  2 files changed, 59 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 0319c21dd208..6f8a2f93187a 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -27,8 +27,41 @@ static int pci_msi_enable = 1;
>  
>  #define msix_table_size(flags)	((flags & PCI_MSIX_FLAGS_QSIZE) + 1)
>  
> -/* Arch hooks */
> +#ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
> +static struct irq_domain *pci_msi_default_domain;
> +
> +struct irq_domain * __weak arch_get_pci_msi_domain(struct pci_dev *dev)
> +{
> +	return pci_msi_default_domain;
> +}
> +
> +static int pci_msi_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
> +{
> +	struct irq_domain *domain;
>  
> +	domain = arch_get_pci_msi_domain(dev);
> +	if (domain)
> +		return pci_msi_domain_alloc_irqs(domain, type, dev);
> +
> +	return arch_setup_msi_irqs(dev, nvec, type);
> +}
> +
> +static void pci_msi_teardown_msi_irqs(struct pci_dev *dev)
> +{
> +	struct irq_domain *domain;
> +
> +	domain = arch_get_pci_msi_domain(dev);
> +	if (domain)
> +		pci_msi_domain_free_irqs(domain, dev);
> +	else
> +		arch_teardown_msi_irqs(dev);
> +}
> +#else
> +#define pci_msi_setup_msi_irqs		arch_setup_msi_irqs
> +#define pci_msi_teardown_msi_irqs	arch_teardown_msi_irqs
> +#endif
> +
> +/* Arch hooks */
>  int __weak arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *desc)
>  {
>  	struct msi_chip *chip = dev->bus->msi;
> @@ -329,7 +362,7 @@ static void free_msi_irqs(struct pci_dev *dev)
>  			for (i = 0; i < entry->nvec_used; i++)
>  				BUG_ON(irq_has_action(entry->irq + i));
>  
> -	arch_teardown_msi_irqs(dev);
> +	pci_msi_teardown_msi_irqs(dev);
>  
>  	list_for_each_entry_safe(entry, tmp, &dev->msi_list, list) {
>  		if (entry->msi_attrib.is_msix) {
> @@ -581,7 +614,7 @@ static int msi_capability_init(struct pci_dev *dev, int nvec)
>  	list_add_tail(&entry->list, &dev->msi_list);
>  
>  	/* Configure MSI capability structure */
> -	ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);
> +	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSI);
>  	if (ret) {
>  		msi_mask_irq(entry, mask, ~mask);
>  		free_msi_irqs(dev);
> @@ -696,7 +729,7 @@ static int msix_capability_init(struct pci_dev *dev,
>  	if (ret)
>  		return ret;
>  
> -	ret = arch_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
> +	ret = pci_msi_setup_msi_irqs(dev, nvec, PCI_CAP_ID_MSIX);
>  	if (ret)
>  		goto out_avail;
>  
> @@ -1183,4 +1216,23 @@ void pci_msi_domain_free_irqs(struct irq_domain *domain, struct pci_dev *dev)
>  {
>  	msi_domain_free_irqs(domain, &dev->dev);
>  }
> +
> +struct irq_domain *pci_msi_create_default_irq_domain(struct device_node *node,
> +		 struct msi_domain_info *info, struct irq_domain *parent)
> +{
> +	struct irq_domain *domain;
> +	static DEFINE_MUTEX(pci_msi_domain_lock);
> +
> +	mutex_lock(&pci_msi_domain_lock);
> +	if (pci_msi_default_domain) {
> +		pr_err("PCI: default irq domain for PCI MSI has already been created.\n");
> +		domain = NULL;
> +	} else {
> +		domain = msi_create_irq_domain(node, info, parent);

Surely this needs to be a call to pci_msi_create_irq_domain().
Otherwise, not much is working on the PCI side...

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

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