Subject: Re: [PATCH v2 08/17] powerpc/powerpc: Add new PCIe functions for allocating cxl interrupts

From: Michael Ellerman <[email-masked]>
Date: Thu, 2 Oct 2014 13:16:59 +1000 (EST)

On Tue, 2014-30-09 at 10:34:57 UTC, Michael Neuling wrote:
> From: Ian Munsie <[email-masked]>
> 
> This adds a number of functions for allocating IRQs under powernv PCIe for cxl.
> 
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 329164f..b0b96f0 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -503,6 +505,138 @@ static struct pnv_ioda_pe *pnv_ioda_get_pe(struct pci_dev *dev)
>  		return NULL;
>  	return &phb->ioda.pe_array[pdn->pe_number];
>  }
> +
> +struct device_node *pnv_pci_to_phb_node(struct pci_dev *dev)
> +{
> +        struct pci_controller *hose = pci_bus_to_host(dev->bus);
> +
> +        return hose->dn;
> +}
> +EXPORT_SYMBOL(pnv_pci_to_phb_node);
> +
> +#ifdef CONFIG_CXL_BASE
> +int pnv_phb_to_cxl(struct pci_dev *dev)
> +{
> +	struct pci_controller *hose = pci_bus_to_host(dev->bus);
> +	struct pnv_phb *phb = hose->private_data;
> +	struct pnv_ioda_pe *pe;
> +	int rc;
> +
> +	if (!(pe = pnv_ioda_get_pe(dev))) {
> +		rc = -ENODEV;
> +		goto out;
> +	}

That'd be a lot simpler as:

	pe = pnv_ioda_get_pe(dev);
	if (!pe)
		return -ENODEV;

> +	pe_info(pe, "switch PHB to CXL\n");
> +	pe_info(pe, "PHB-ID  : 0x%016llx\n", phb->opal_id);
> +	pe_info(pe, "     pe : %i\n", pe->pe_number);

Spacing is a bit weird but maybe it matches something else?

> +
> +	if ((rc = opal_pci_set_phb_cxl_mode(phb->opal_id, 1, pe->pe_number)))
> +		dev_err(&dev->dev, "opal_pci_set_phb_cxl_mode failed: %i\n", rc);

Again why not:

	rc = opal_pci_set_phb_cxl_mode(phb->opal_id, 1, pe->pe_number);
	if (rc)
		dev_err(&dev->dev, "opal_pci_set_phb_cxl_mode failed: %i\n", rc);

> +out:
> +	return rc;
> +}
> +EXPORT_SYMBOL(pnv_phb_to_cxl);
> +

> +int pnv_cxl_alloc_hwirq_ranges(struct cxl_irq_ranges *irqs,
> +			       struct pci_dev *dev, int num)

This could use some documentation.

It seems to be that it allocates num irqs in some number of ranges, up to
CXL_IRQ_RANGES?

> +{
> +	struct pci_controller *hose = pci_bus_to_host(dev->bus);
> +	struct pnv_phb *phb = hose->private_data;
> +	int range = 0;

You reinitialise to 1 below?

> +	int hwirq;
> +	int try;

So these can be:

	int hwirq, try, range;

> +	memset(irqs, 0, sizeof(struct cxl_irq_ranges));
> +
> +	for (range = 1; range < CXL_IRQ_RANGES && num; range++) {

I think this would be clearer if range was just called "i" as usual.

Why does it start at 1 ?

> +		try = num;
> +		while (try) {
> +			hwirq = msi_bitmap_alloc_hwirqs(&phb->msi_bmp, try);
> +			if (hwirq >= 0)
> +				break;
> +			try /= 2;
> +		}
> +		if (!try)
> +			goto fail;
> +
> +		irqs->offset[range] = phb->msi_base + hwirq;
> +		irqs->range[range] = try;

irqs->range is irq_hw_number_t but looks like it should just be uint.

> +		pr_devel("cxl alloc irq range 0x%x: offset: 0x%lx  limit: %li\n",
> +			 range, irqs->offset[range], irqs->range[range]);
> +		num -= try;
> +	}
> +	if (num)
> +		goto fail;
> +
> +	return 0;
> +fail:
> +	for (range--; range >= 0; range--) {
> +		hwirq = irqs->offset[range] - phb->msi_base;
> +		msi_bitmap_free_hwirqs(&phb->msi_bmp, hwirq,
> +				       irqs->range[range]);
> +		irqs->range[range] = 0;
> +	}

Because you zero ranges at the top I think you can replace all of the fail
logic with a call to pnv_cxl_release_hwirq_ranges().

> +	return -ENOSPC;
> +}
> +EXPORT_SYMBOL(pnv_cxl_alloc_hwirq_ranges);
> +
> +void pnv_cxl_release_hwirq_ranges(struct cxl_irq_ranges *irqs,
> +				  struct pci_dev *dev)
> +{
> +	struct pci_controller *hose = pci_bus_to_host(dev->bus);
> +	struct pnv_phb *phb = hose->private_data;
> +	int range = 0;

Unnecessary init again.

> +	int hwirq;
> +
> +	for (range = 0; range < 4; range++) {

Shouldn't 4 be CXL_IRQ_RANGES ?

> +		hwirq = irqs->offset[range] - phb->msi_base;

That should be inside the if.

Or better do:
		if (!irqs->range[range])
			continue;
		...

> +		if (irqs->range[range]) {
> +			pr_devel("cxl release irq range 0x%x: offset: 0x%lx  limit: %ld\n",
> +				 range, irqs->offset[range],
> +				 irqs->range[range]);
> +			msi_bitmap_free_hwirqs(&phb->msi_bmp, hwirq,
> +					       irqs->range[range]);
> +		}
> +	}
> +}
> +EXPORT_SYMBOL(pnv_cxl_release_hwirq_ranges);
> +
> +int pnv_cxl_get_irq_count(struct pci_dev *dev)
> +{
> +	struct pci_controller *hose = pci_bus_to_host(dev->bus);
> +        struct pnv_phb *phb = hose->private_data;

Indentation is fubar.

> +	return phb->msi_bmp.irq_count;
> +}
> +EXPORT_SYMBOL(pnv_cxl_get_irq_count);
> +
> +#endif /* CONFIG_CXL_BASE */
>  #endif /* CONFIG_PCI_MSI */
>  
>  static int pnv_ioda_configure_pe(struct pnv_phb *phb, struct pnv_ioda_pe *pe)
> @@ -1330,6 +1464,33 @@ static void set_msi_irq_chip(struct pnv_phb *phb, unsigned int virq)
>  	irq_set_chip(virq, &phb->ioda.irq_chip);
>  }
>  
> +#ifdef CONFIG_CXL_BASE

Why is this here and not in the previous #ifdef CONFIG_CXL_BASE block ?

> +int pnv_cxl_ioda_msi_setup(struct pci_dev *dev, unsigned int hwirq,
> +			   unsigned int virq)
> +{
> +	struct pci_controller *hose = pci_bus_to_host(dev->bus);
> +	struct pnv_phb *phb = hose->private_data;
> +	unsigned int xive_num = hwirq - phb->msi_base;
> +	struct pnv_ioda_pe *pe;
> +	int rc;
> +
> +	if (!(pe = pnv_ioda_get_pe(dev)))
> +		return -ENODEV;
> +
> +	/* Assign XIVE to PE */
> +	rc = opal_pci_set_xive_pe(phb->opal_id, pe->pe_number, xive_num);
> +	if (rc) {
> +		pr_warn("%s: OPAL error %d setting msi_base 0x%x hwirq 0x%x XIVE 0x%x PE\n",
> +			pci_name(dev), rc, phb->msi_base, hwirq, xive_num);

dev_warn() ?

cheers