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Subject[PATCH 3/3] PCI: Extend and export pci_msi_supported() for multivector MSI
Date
Embrace and extend this existing function as an interface to test
for multivector MSI support. Drivers can now call this function
with nvec >1 and type PCI_CAP_ID_MSI to verify whether the platform
is capable of supporting multiple MSI vectors.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---

drivers/pci/msi.c | 15 ++++++++++++---
include/linux/pci.h | 3 +++
2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
index 36b503a..da3c709 100644
--- a/drivers/pci/msi.c
+++ b/drivers/pci/msi.c
@@ -793,12 +793,13 @@ out_free:
* pci_msi_supported - check whether MSI may be enabled on a device
* @dev: pointer to the pci_dev data structure of MSI device function
* @nvec: how many MSIs have been requested ?
+ * @type: PCI_CAP_ID_MSI or PCI_CAP_ID_MSIX
*
* Look at global flags, the device itself, and its parent buses
* 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, int type)
{
struct pci_bus *bus;

@@ -809,6 +810,9 @@ static int pci_msi_supported(struct pci_dev *dev, int nvec)
if (!dev || dev->no_msi || dev->current_state != PCI_D0)
return 0;

+ if (type != PCI_CAP_ID_MSI && type != PCI_CAP_ID_MSIX)
+ return 0;
+
/*
* You can't ask to have 0 or less MSIs configured.
* a) it's stupid ..
@@ -828,8 +832,13 @@ static int pci_msi_supported(struct pci_dev *dev, int nvec)
if (bus->bus_flags & PCI_BUS_FLAGS_NO_MSI)
return 0;

+ if (type == PCI_CAP_ID_MSI && nvec > 1 &&
+ !arch_supports_multivector_msi(dev))
+ return 0;
+
return 1;
}
+EXPORT_SYMBOL(pci_msi_supported);

/**
* pci_msi_vec_count - Return the number of MSI vectors a device can send
@@ -930,7 +939,7 @@ int pci_enable_msix(struct pci_dev *dev, struct msix_entry *entries, int nvec)
int nr_entries;
int i, j;

- if (!pci_msi_supported(dev, nvec))
+ if (!pci_msi_supported(dev, nvec, PCI_CAP_ID_MSIX))
return -EINVAL;

if (!entries)
@@ -1041,7 +1050,7 @@ int pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec)
int nvec;
int rc;

- if (!pci_msi_supported(dev, minvec))
+ if (!pci_msi_supported(dev, minvec, PCI_CAP_ID_MSI))
return -EINVAL;

WARN_ON(!!dev->msi_enabled);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c9a8904..f20605e 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1197,6 +1197,7 @@ struct msix_entry {


#ifdef CONFIG_PCI_MSI
+int pci_msi_supported(struct pci_dev *dev, int nvec, int type);
int pci_msi_vec_count(struct pci_dev *dev);
void pci_msi_shutdown(struct pci_dev *dev);
void pci_disable_msi(struct pci_dev *dev);
@@ -1225,6 +1226,8 @@ static inline int pci_enable_msix_exact(struct pci_dev *dev,
return 0;
}
#else
+static inline int pci_msi_supported(struct pci_dev *dev, int nvec, int type)
+{ return 0; }
static inline int pci_msi_vec_count(struct pci_dev *dev) { return -ENOSYS; }
static inline void pci_msi_shutdown(struct pci_dev *dev) { }
static inline void pci_disable_msi(struct pci_dev *dev) { }


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