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

Michael Ellerman
2014-10-02T03:17:04Z

On Tue, 2014-30-09 at 10:34:57 UTC, Michael Neuling wrote:
> From: Ian Munsie <imunsie@au1.ibm.com>
>
> 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