[PATCH 6/8] pci: provide sensible irq vector alloc/free routines

Christoph Hellwig
2016-04-16T01:36:07Z

Hide all the MSI-X vs MSI vs legacy bullshit, and provide an array of
interrupt vectors in the pci_dev structure, and ensure we get proper
interrupt affinity by default.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/pci/irq.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
drivers/pci/msi.c | 2 +-
drivers/pci/pci.h | 5 +++
include/linux/pci.h | 5 +++
4 files changed, 99 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/irq.c b/drivers/pci/irq.c
index 6684f15..b683465 100644
--- a/drivers/pci/irq.c
+++ b/drivers/pci/irq.c
@@ -1,7 +1,8 @@
/*
- * PCI IRQ failure handing code
+ * PCI IRQ handing code
*
* Copyright (c) 2008 James Bottomley <James.Bottomley@HansenPartnership.com>
+ * Copyright (c) 2016 Christoph Hellwig.
*/

#include <linux/acpi.h>
@@ -9,6 +10,92 @@
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/pci.h>
+#include <linux/interrupt.h>
+#include "pci.h"
+
+static 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,
+ int nr_vecs)
+{
+ struct msix_entry *msix_entries;
+ int vecs, i;
+
+ msix_entries = kcalloc(nr_vecs, sizeof(struct msix_entry), GFP_KERNEL);
+ if (!msix_entries)
+ return -ENOMEM;
+
+ for (i = 0; i < nr_vecs; i++)
+ msix_entries[i].entry = i;
+
+ vecs = pci_enable_msix_range(pdev, msix_entries, 1, nr_vecs);
+ if (vecs > 0) {
+ for (i = 0; i < vecs; i++)
+ irqs[i] = msix_entries[i].vector;
+ }
+
+ kfree(msix_entries);
+ return vecs;
+}
+
+int pci_alloc_irq_vectors(struct pci_dev *pdev, int nr_vecs)
+{
+ int vecs, ret, i;
+ u32 *irqs;
+
+ nr_vecs = min(nr_vecs, pci_nr_irq_vectors(pdev));
+
+ irqs = kcalloc(nr_vecs, sizeof(u32), GFP_KERNEL);
+ if (!irqs)
+ return -ENOMEM;
+
+ vecs = pci_enable_msix_range_wrapper(pdev, irqs, nr_vecs);
+ if (vecs <= 0) {
+ vecs = pci_enable_msi_range(pdev, 1, min(nr_vecs, 32));
+ if (vecs <= 0) {
+ ret = -EIO;
+ if (!pdev->irq)
+ goto out_free_irqs;
+
+ /* use legacy irq */
+ vecs = 1;
+ }
+
+ for (i = 0; i < vecs; i++)
+ irqs[i] = pdev->irq + i;
+ }
+
+ pdev->irqs = irqs;
+ return vecs;
+
+out_free_irqs:
+ kfree(irqs);
+ return ret;
+}
+EXPORT_SYMBOL(pci_alloc_irq_vectors);
+
+void pci_free_irq_vectors(struct pci_dev *pdev)
+{
+ if (pdev->msi_enabled)
+ pci_disable_msi(pdev);
+ else if (pdev->msix_enabled)
+ pci_disable_msix(pdev);
+
+ kfree(pdev->dev.irq_affinity);
+ pdev->dev.irq_affinity = NULL;
+ kfree(pdev->irqs);
+}
+EXPORT_SYMBOL(pci_free_irq_vectors);

static void pci_note_irq_problem(struct pci_dev *pdev, const char *reason)
{
diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index a080f44..544d306 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -815,7 +815,7 @@ out_free:
* to determine if MSI/-X are supported for the device. If MSI/-X is
* supported return 1, else return 0.
**/
-static int pci_msi_supported(struct pci_dev *dev, int nvec)
+int pci_msi_supported(struct pci_dev *dev, int nvec)
{
struct pci_bus *bus;

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index d0fb934..263422c 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -144,8 +144,13 @@ extern unsigned int pci_pm_d3_delay;

#ifdef CONFIG_PCI_MSI
void pci_no_msi(void);
+int pci_msi_supported(struct pci_dev *dev, int nvec);
#else
static inline void pci_no_msi(void) { }
+static int pci_msi_supported(struct pci_dev *dev, int nvec)
+{
+ return 0;
+}
#endif

static inline void pci_msi_set_enable(struct pci_dev *dev, int enable)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 004b813..4fbc14f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -322,6 +322,7 @@ 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 */
@@ -1235,6 +1236,9 @@ 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);

+int pci_alloc_irq_vectors(struct pci_dev *dev, int nr_vecs);
+void pci_free_irq_vectors(struct pci_dev *pdev);
+
/* kmem_cache style wrapper around pci_alloc_consistent() */

#include <linux/pci-dma.h>
@@ -1282,6 +1286,7 @@ static inline int pci_enable_msix_exact(struct pci_dev *dev,
return rc;
return 0;
}
+
#else
static inline int pci_msi_vec_count(struct pci_dev *dev) { return -ENOSYS; }
static inline void pci_msi_shutdown(struct pci_dev *dev) { }
--
2.1.4