| Message ID | d0d8cd19befa8757faf7660fd3ae619945b2cde4.1387140921.git.agordeev@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Mon, Dec 16, 2013 at 09:34:59AM +0100, Alexander Gordeev wrote: > Device drivers can use this interface to obtain maximum number > of MSI interrupts the device supports and use that number i.e. > in a following call to pci_enable_msi_block() interface. > > Signed-off-by: Alexander Gordeev <agordeev@redhat.com> > Reviewed-by: Tejun Heo <tj@kernel.org> > --- > Documentation/PCI/MSI-HOWTO.txt | 15 ++++++++++++++ > drivers/pci/msi.c | 41 +++++++++++++++++++++++++++++++------- > include/linux/pci.h | 6 +++++ > 3 files changed, 54 insertions(+), 8 deletions(-) > > diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt > index a4d174e..c03b815 100644 > --- a/Documentation/PCI/MSI-HOWTO.txt > +++ b/Documentation/PCI/MSI-HOWTO.txt > @@ -169,6 +169,21 @@ on any interrupt for which it previously called request_irq(). > Failure to do so results in a BUG_ON(), leaving the device with > MSI enabled and thus leaking its vector. > > +4.2.5 pci_get_msi_vec_count > + > +int pci_get_msi_vec_count(struct pci_dev *dev) What would you think of "pci_msi_vec_count()" or "pci_msi_vector_count()" instead? The "get" doesn't really seem necessary, and we often use "get" to indicate acquiring a reference (though it's obvious that doesn't apply here). Bjorn > +This function could be used to retrieve the number of MSI vectors the > +device requested (via the Multiple Message Capable register). The MSI > +specification only allows the returned value to be a power of two, > +up to a maximum of 2^5 (32). > + > +If this function returns a negative number, it indicates the device is > +not capable of sending MSIs. > + > +If this function returns a positive number, it indicates the maximum > +number of MSI interrupt vectors that could be allocated. > + > 4.3 Using MSI-X > > The MSI-X capability is much more flexible than the MSI capability. > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c > index c0e2259..8915edb 100644 > --- a/drivers/pci/msi.c > +++ b/drivers/pci/msi.c > @@ -834,6 +834,31 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) > } > > /** > + * pci_get_msi_vec_count - Return the number of MSI vectors a device can send > + * @dev: device to report about > + * > + * This function returns the number of MSI vectors a device requested via > + * Multiple Message Capable register. It returns a negative errno if the > + * device is not capable sending MSI interrupts. Otherwise, the call succeeds > + * and returns a power of two, up to a maximum of 2^5 (32), according to the > + * MSI specification. > + **/ > +int pci_get_msi_vec_count(struct pci_dev *dev) > +{ > + int ret; > + u16 msgctl; > + > + if (!dev->msi_cap) > + return -EINVAL; > + > + pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); > + ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); > + > + return ret; > +} > +EXPORT_SYMBOL(pci_get_msi_vec_count); > + > +/** > * pci_enable_msi_block - configure device's MSI capability structure > * @dev: device to configure > * @nvec: number of interrupts to configure > @@ -849,13 +874,13 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) > int pci_enable_msi_block(struct pci_dev *dev, int nvec) > { > int status, maxvec; > - u16 msgctl; > > - if (!dev->msi_cap || dev->current_state != PCI_D0) > + if (dev->current_state != PCI_D0) > return -EINVAL; > > - pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); > - maxvec = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); > + maxvec = pci_get_msi_vec_count(dev); > + if (maxvec < 0) > + return maxvec; > if (nvec > maxvec) > return maxvec; > > @@ -880,13 +905,13 @@ EXPORT_SYMBOL(pci_enable_msi_block); > int pci_enable_msi_block_auto(struct pci_dev *dev, int *maxvec) > { > int ret, nvec; > - u16 msgctl; > > - if (!dev->msi_cap || dev->current_state != PCI_D0) > + if (dev->current_state != PCI_D0) > return -EINVAL; > > - pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); > - ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); > + ret = pci_get_msi_vec_count(dev); > + if (ret < 0) > + return ret; > > if (maxvec) > *maxvec = ret; > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 8cf7b15..997751d 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -1154,6 +1154,11 @@ struct msix_entry { > > > #ifndef CONFIG_PCI_MSI > +static inline int pci_get_msi_vec_count(struct pci_dev *dev) > +{ > + return -ENOSYS; > +} > + > static inline int pci_enable_msi_block(struct pci_dev *dev, int nvec) > { > return -ENOSYS; > @@ -1195,6 +1200,7 @@ static inline int pci_msi_enabled(void) > return 0; > } > #else > +int pci_get_msi_vec_count(struct pci_dev *dev); > int pci_enable_msi_block(struct pci_dev *dev, int nvec); > int pci_enable_msi_block_auto(struct pci_dev *dev, int *maxvec); > void pci_msi_shutdown(struct pci_dev *dev); > -- > 1.7.7.6 > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/PCI/MSI-HOWTO.txt b/Documentation/PCI/MSI-HOWTO.txt index a4d174e..c03b815 100644 --- a/Documentation/PCI/MSI-HOWTO.txt +++ b/Documentation/PCI/MSI-HOWTO.txt @@ -169,6 +169,21 @@ on any interrupt for which it previously called request_irq(). Failure to do so results in a BUG_ON(), leaving the device with MSI enabled and thus leaking its vector. +4.2.5 pci_get_msi_vec_count + +int pci_get_msi_vec_count(struct pci_dev *dev) + +This function could be used to retrieve the number of MSI vectors the +device requested (via the Multiple Message Capable register). The MSI +specification only allows the returned value to be a power of two, +up to a maximum of 2^5 (32). + +If this function returns a negative number, it indicates the device is +not capable of sending MSIs. + +If this function returns a positive number, it indicates the maximum +number of MSI interrupt vectors that could be allocated. + 4.3 Using MSI-X The MSI-X capability is much more flexible than the MSI capability. diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index c0e2259..8915edb 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -834,6 +834,31 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) } /** + * pci_get_msi_vec_count - Return the number of MSI vectors a device can send + * @dev: device to report about + * + * This function returns the number of MSI vectors a device requested via + * Multiple Message Capable register. It returns a negative errno if the + * device is not capable sending MSI interrupts. Otherwise, the call succeeds + * and returns a power of two, up to a maximum of 2^5 (32), according to the + * MSI specification. + **/ +int pci_get_msi_vec_count(struct pci_dev *dev) +{ + int ret; + u16 msgctl; + + if (!dev->msi_cap) + return -EINVAL; + + pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); + ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + + return ret; +} +EXPORT_SYMBOL(pci_get_msi_vec_count); + +/** * pci_enable_msi_block - configure device's MSI capability structure * @dev: device to configure * @nvec: number of interrupts to configure @@ -849,13 +874,13 @@ static int pci_msi_check_device(struct pci_dev *dev, int nvec, int type) int pci_enable_msi_block(struct pci_dev *dev, int nvec) { int status, maxvec; - u16 msgctl; - if (!dev->msi_cap || dev->current_state != PCI_D0) + if (dev->current_state != PCI_D0) return -EINVAL; - pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); - maxvec = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + maxvec = pci_get_msi_vec_count(dev); + if (maxvec < 0) + return maxvec; if (nvec > maxvec) return maxvec; @@ -880,13 +905,13 @@ EXPORT_SYMBOL(pci_enable_msi_block); int pci_enable_msi_block_auto(struct pci_dev *dev, int *maxvec) { int ret, nvec; - u16 msgctl; - if (!dev->msi_cap || dev->current_state != PCI_D0) + if (dev->current_state != PCI_D0) return -EINVAL; - pci_read_config_word(dev, dev->msi_cap + PCI_MSI_FLAGS, &msgctl); - ret = 1 << ((msgctl & PCI_MSI_FLAGS_QMASK) >> 1); + ret = pci_get_msi_vec_count(dev); + if (ret < 0) + return ret; if (maxvec) *maxvec = ret; diff --git a/include/linux/pci.h b/include/linux/pci.h index 8cf7b15..997751d 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1154,6 +1154,11 @@ struct msix_entry { #ifndef CONFIG_PCI_MSI +static inline int pci_get_msi_vec_count(struct pci_dev *dev) +{ + return -ENOSYS; +} + static inline int pci_enable_msi_block(struct pci_dev *dev, int nvec) { return -ENOSYS; @@ -1195,6 +1200,7 @@ static inline int pci_msi_enabled(void) return 0; } #else +int pci_get_msi_vec_count(struct pci_dev *dev); int pci_enable_msi_block(struct pci_dev *dev, int nvec); int pci_enable_msi_block_auto(struct pci_dev *dev, int *maxvec); void pci_msi_shutdown(struct pci_dev *dev);