Introduce pci_enable_msi/msix_range() interfaces

This series is against "next" branch in Bjorn's repo:
git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git

Changes from v4 to v5:
- pci_auto_enable_msi* functions renamed to pci_enable_msi* ones;
- pci_enable_msi_range() and pci_enable_msix_range() are the only

    basic interfaces left to enable MSI/MSI-X operation;
  - pci_enable_msi(), pci_enable_msi_block() and pci_enable_msix() old
    interfaces deprecated in favour of pci_enable_msi/msix_range() ones;
    description of the old interfaces is removed from the documentation;
  - pci_get_msi_vec_count()  renamed to pci_msi_vec_count() and
    pci_get_msix_vec_count() renamed to pci_msix_vec_count();

Changes from v3 to v4:
- pcim_enable_msi* functions renamed to pci_auto_enable_msi* ones;
- PowerPC patches dropped;
- pci_get_msi_cap() renamed to pci_get_msi_vec_count() and

    pci_msix_table_size() renamed to pci_get_msix_vec_count();

Changes from v2 to v3:
- new public interfaces commented in drivers/pci/msi.c;
- patch "Make quota traversing and requesting race-safe" explained;
- pci_enable_msi/msix() 'nvec' arg type changed from 'unsigned int' to 'int';
- pcim_enable_msi*() arg 'nvec' renamed to 'maxvec' when upper limit passed;
- pcim_enable_msi*(..., maxvec, minvec) arg order swapped to minvec, maxvec;
- "PCI: Fail MSI/MSI-X initialization if device is not in PCI_D0" commit 869a161 and "PCI/MSI: Factor out pci_get_msi_cap() interface" patch conflicts resolved;

This update introduces pci_enable_msi_range() function which supersedes pci_enable_msi() and pci_enable_msi_block() interfaces for MSI and pci_enable_msi_range() function which supersedes pci_enable_msix() interface for MSI-X interrupts.

The plan is to convert all drivers to the new interfaces and then remove existing pci_enable_msi(), pci_enable_msi_block() and pci_enable_msix() functions.

The newly introduced functions return either a negative error code or a number of successfully allocated MSI/MSI-X interrupts.

Unlike the old interfaces where the "third" state indicates a possible number of MSI interrupts that could have been allocated, the new interfaces allow device drivers not to deal with tri-state return values and hide fallback logic behind the implementation.

As result, device drivers are expected to have more clearer and straight code.

The tree could be found in "pci-next-msi-v5" branch in repo:
https://github.com/a-gordeev/linux.git

Alexander Gordeev (4):
PCI/MSI: Factor out pci_msi_vec_count() interface PCI/MSI: Get rid of pci_enable_msi_block_auto() interface PCI/MSI: Introduce pci_msix_vec_count() interface PCI/MSI: Introduce pci_enable_msi/msix_range() interfaces

 Documentation/PCI/MSI-HOWTO.txt |  308 ++++++++++++++++++++++++++-------------
 drivers/ata/ahci.c              |   56 +++++---
 drivers/pci/msi.c               |  150 +++++++++++++++-----
 drivers/pci/pcie/portdrv_core.c |    7 +-
 include/linux/pci.h             |   27 +++-
 5 files changed, 385 insertions(+), 163 deletions(-)

1.7.7.6