Add a helper to allocate a range of interrupt vectors, which will
transparently use MSI-X and MSI if available or fallback to legacy
vectors. The interrupts are available in a core managed array
in the pci_dev structure, and can also be released using a similar
helper.
The next patch will also add automatic spreading of MSI / MSI-X
vectors to this function.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
drivers/pci/msi.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/pci.h | 18 +++++++++
2 files changed, 128 insertions(+)
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index a080f44..a33adec 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -4,6 +4,7 @@
*
* Copyright (C) 2003-2004 Intel
* Copyright (C) Tom Long Nguyen (tom.l.nguyen@xxxxxxxxx)
+ * Copyright (c) 2016 Christoph Hellwig.
*/
#include <linux/err.h>
@@ -1120,6 +1121,115 @@ int pci_enable_msix_range(struct pci_dev *dev, struct msix_entry *entries,
}
EXPORT_SYMBOL(pci_enable_msix_range);
+static unsigned int pci_nr_irq_vectors(struct pci_dev *pdev)
+{
+ int nr_entries;
+
+ nr_entries = pci_msix_vec_count(pdev);
+ if (nr_entries <= 0 && pci_msi_supported(pdev, 1))
+ nr_entries = pci_msi_vec_count(pdev);
+ if (nr_entries <= 0)
+ nr_entries = 1;
+ return nr_entries;
+}
+
+static int pci_enable_msix_range_wrapper(struct pci_dev *pdev, u32 *irqs,
+ unsigned int min_vecs, unsigned int max_vecs)
+{
+ struct msix_entry *msix_entries;
+ int vecs, i;
+
+ msix_entries = kcalloc(max_vecs, sizeof(struct msix_entry), GFP_KERNEL);
+ if (!msix_entries)
+ return -ENOMEM;
+
+ for (i = 0; i < max_vecs; i++)
+ msix_entries[i].entry = i;
+
+ vecs = pci_enable_msix_range(pdev, msix_entries, min_vecs, max_vecs);
+ if (vecs > 0) {
+ for (i = 0; i < vecs; i++)
+ irqs[i] = msix_entries[i].vector;
+ }
+
+ kfree(msix_entries);
+ return vecs;
+}
+
+/**
+ * pci_alloc_irq_vectors - allocate multiple IRQs for a device
+ * @dev: PCI device to operate on
+ * @min_vecs: minimum number of vectors required (must be >= 1)
+ * @max_vecs: maximum (desired) number of vectors
+ * @flags: flags or quirks for the allocation
+ *
+ * Allocate up to @max_vecs interrupt vectors for @dev, using MSI-X or MSI
+ * vectors if available, and fall back to a single legacy vector
+ * if neither is available. Return the number of vectors allocated,
+ * (which might be smaller than @max_vecs) if successful, or a negative
+ * error code on error. The Linux irq numbers for the allocated
+ * vectors are stored in pdev->irqs. If less than @min_vecs interrupt
+ * vectors are available for @dev the function will fail with -ENOSPC.
+ */
+int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
+ unsigned int max_vecs, unsigned int flags)
+{
+ unsigned int vecs, i;
+ u32 *irqs;
+
+ max_vecs = min(max_vecs, pci_nr_irq_vectors(dev));
+
+ irqs = kcalloc(max_vecs, sizeof(u32), GFP_KERNEL);
+ if (!irqs)
+ return -ENOMEM;
+
+ if (!(flags & PCI_IRQ_NOMSIX)) {
+ vecs = pci_enable_msix_range_wrapper(dev, irqs, min_vecs,
+ max_vecs);
+ if (vecs > 0)
+ goto done;
+ }
+
+ vecs = pci_enable_msi_range(dev, min_vecs, max_vecs);
+ if (vecs > 0) {
+ for (i = 0; i < vecs; i++)
+ irqs[i] = dev->irq + i;
+ goto done;
+ }
+
+ if (min_vecs > 1)
+ return -ENOSPC;
+
+ /* use legacy irq */
+ kfree(irqs);
+ dev->irqs = &dev->irq;
+ return 1;
+
+done:
+ dev->irqs = irqs;
+ return vecs;
+}
+EXPORT_SYMBOL(pci_alloc_irq_vectors);
+
+/**
+ * pci_free_irq_vectors - free previously allocated IRQs for a device
+ * @dev: PCI device to operate on
+ *
+ * Undoes the allocations and enabling in pci_alloc_irq_vectors().
+ */
+void pci_free_irq_vectors(struct pci_dev *dev)
+{
+ if (dev->msix_enabled)
+ pci_disable_msix(dev);
+ else if (dev->msi_enabled)
+ pci_disable_msi(dev);
+
+ if (dev->irqs != &dev->irq)
+ kfree(dev->irqs);
+}
+EXPORT_SYMBOL(pci_free_irq_vectors);
+
+
struct pci_dev *msi_desc_to_pci_dev(struct msi_desc *desc)
{
return to_pci_dev(desc->dev);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index b67e4df..84a20fc 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -320,6 +320,7 @@ struct pci_dev {
* directly, use the values stored here. They might be different!
*/
unsigned int irq;
+ unsigned int *irqs;
struct resource resource[DEVICE_COUNT_RESOURCE]; /* I/O and memory regions + expansion ROMs */
bool match_driver; /* Skip attaching driver */
@@ -1237,6 +1238,8 @@ resource_size_t pcibios_iov_resource_alignment(struct pci_dev *dev, int resno);
int pci_set_vga_state(struct pci_dev *pdev, bool decode,
unsigned int command_bits, u32 flags);
+#define PCI_IRQ_NOMSIX (1 << 0) /* don't try to use MSI-X interrupts */
+
/* kmem_cache style wrapper around pci_alloc_consistent() */
#include <linux/pci-dma.h>
@@ -1284,6 +1287,9 @@ static inline int pci_enable_msix_exact(struct pci_dev *dev,
return rc;
return 0;
}
+int pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
+ unsigned int max_vecs, unsigned int flags);
+void pci_free_irq_vectors(struct pci_dev *dev);
#else
static inline int pci_msi_vec_count(struct pci_dev *dev) { return -ENOSYS; }
static inline void pci_msi_shutdown(struct pci_dev *dev) { }
@@ -1307,6 +1313,18 @@ static inline int pci_enable_msix_range(struct pci_dev *dev,
static inline int pci_enable_msix_exact(struct pci_dev *dev,
struct msix_entry *entries, int nvec)
{ return -ENOSYS; }
+static inline int pci_alloc_irq_vectors(struct pci_dev *dev,
+ unsigned int min_vecs, unsigned int max_vecs,
+ unsigned int flags)
+{
+ if (min_vecs > 1)
+ return -ENOSPC;
+ dev->irqs = &dev->irq;
+ return 1;
+}
+static inline void pci_free_irq_vectors(struct pci_dev *dev)
+{
+}
#endif
#ifdef CONFIG_PCIEPORTBUS
--
2.1.4
--
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