Commit-ID: 08261d87f7d1b6253ab3223756625a5c74532293 Gitweb: http://git.kernel.org/tip/08261d87f7d1b6253ab3223756625a5c74532293 Author: Alexander Gordeev <agord...@redhat.com> AuthorDate: Mon, 19 Nov 2012 16:02:10 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 24 Jan 2013 17:25:13 +0100
PCI/MSI: Enable multiple MSIs with pci_enable_msi_block_auto() The new function pci_enable_msi_block_auto() tries to allocate maximum possible number of MSIs up to the number the device supports. It generalizes a pattern when pci_enable_msi_block() is contiguously called until it succeeds or fails. Opposite to pci_enable_msi_block() which takes the number of MSIs to allocate as a input parameter, pci_enable_msi_block_auto() could be used by device drivers to obtain the number of assigned MSIs and the number of MSIs the device supports. Signed-off-by: Alexander Gordeev <agord...@redhat.com> Acked-by: Bjorn Helgaas <bhelg...@google.com> Cc: Suresh Siddha <suresh.b.sid...@intel.com> Cc: Yinghai Lu <ying...@kernel.org> Cc: Matthew Wilcox <wi...@linux.intel.com> Cc: Jeff Garzik <jgar...@pobox.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Peter Zijlstra <a.p.zijls...@chello.nl> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/c3de2419df94a0f95ca1a6f755afc421486455e6.1353324359.git.agord...@redhat.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- Documentation/PCI/MSI-HOWTO.txt | 37 ++++++++++++++++++++++++++++++++----- drivers/pci/msi.c | 26 ++++++++++++++++++++++++++ include/linux/pci.h | 7 +++++++ 3 files changed, 65 insertions(+), 5 deletions(-) diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt index 53e6fca..a091780 100644 --- a/Documentation/PCI/MSI-HOWTO.txt +++ b/Documentation/PCI/MSI-HOWTO.txt @@ -127,15 +127,42 @@ on the number of vectors that can be allocated; pci_enable_msi_block() returns as soon as it finds any constraint that doesn't allow the call to succeed. -4.2.3 pci_disable_msi +4.2.3 pci_enable_msi_block_auto + +int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *count) + +This variation on pci_enable_msi() call allows a device driver to request +the maximum possible number of MSIs. The MSI specification only allows +interrupts to be allocated in powers of two, up to a maximum of 2^5 (32). + +If this function returns a positive number, it indicates that it has +succeeded and the returned value is the number of allocated interrupts. In +this case, the function enables MSI on this device and updates dev->irq to +be the lowest of the new interrupts assigned to it. The other interrupts +assigned to the device are in the range dev->irq to dev->irq + returned +value - 1. + +If this function returns a negative number, it indicates an error and +the driver should not attempt to request any more MSI interrupts for +this device. + +If the device driver needs to know the number of interrupts the device +supports it can pass the pointer count where that number is stored. The +device driver must decide what action to take if pci_enable_msi_block_auto() +succeeds, but returns a value less than the number of interrupts supported. +If the device driver does not need to know the number of interrupts +supported, it can set the pointer count to NULL. + +4.2.4 pci_disable_msi void pci_disable_msi(struct pci_dev *dev) This function should be used to undo the effect of pci_enable_msi() or -pci_enable_msi_block(). Calling it restores dev->irq to the pin-based -interrupt number and frees the previously allocated message signaled -interrupt(s). The interrupt may subsequently be assigned to another -device, so drivers should not cache the value of dev->irq. +pci_enable_msi_block() or pci_enable_msi_block_auto(). Calling it restores +dev->irq to the pin-based interrupt number and frees the previously +allocated message signaled interrupt(s). The interrupt may subsequently be +assigned to another device, so drivers should not cache the value of +dev->irq. Before calling this function, a device driver must always call free_irq() on any interrupt for which it previously called request_irq(). diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index 5099636..00cc78c 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -845,6 +845,32 @@ int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec) } EXPORT_SYMBOL(pci_enable_msi_block); +int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec) +{ + int ret, pos, nvec; + u16 msgctl; + + pos = pci_find_capability(dev, PCI_CAP_ID_MSI); + if (!pos) + return -EINVAL; + + pci_read_config_word(dev, pos + PCI_MSI_FLAGS, &msgctl); + ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + + if (maxvec) + *maxvec = ret; + + do { + nvec = ret; + ret = pci_enable_msi_block(dev, nvec); + } while (ret > 0); + + if (ret < 0) + return ret; + return nvec; +} +EXPORT_SYMBOL(pci_enable_msi_block_auto); + void pci_msi_shutdown(struct pci_dev *dev) { struct msi_desc *desc; diff --git a/include/linux/pci.h b/include/linux/pci.h index 15472d6..6fa4dd2 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1101,6 +1101,12 @@ static inline int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec) return -1; } +static inline int +pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec) +{ + return -1; +} + static inline void pci_msi_shutdown(struct pci_dev *dev) { } static inline void pci_disable_msi(struct pci_dev *dev) @@ -1132,6 +1138,7 @@ static inline int pci_msi_enabled(void) } #else extern int pci_enable_msi_block(struct pci_dev *dev, unsigned int nvec); +extern int pci_enable_msi_block_auto(struct pci_dev *dev, unsigned int *maxvec); extern void pci_msi_shutdown(struct pci_dev *dev); extern void pci_disable_msi(struct pci_dev *dev); extern int pci_msix_table_size(struct pci_dev *dev); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
