Add the new API pci_enable_msi_block() to allow drivers to
request multiple MSI and reimplement pci_enable_msi in terms of
pci_enable_msi_block.  Ensure that the architecture back ends don't
have to know about multiple MSI.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Since most of the callers already know whether they have an MSI or
an MSI-X capability, split msi_set_mask_bits() into msi_mask_irq()
and msix_mask_irq().  The only callers which don't (mask_msi_irq()
and unmask_msi_irq()) can share code in msi_set_mask_bit().  This then
becomes the only caller of msix_flush_writes(), so we can inline it.
The flushing read can be to any address that belongs to the device,
so we can eliminate the calculation too.

We can also get rid of maskbits_mask from struct msi_desc and simply
recalculate it on the rare occasion that we need it.  The single-bit
'masked' element is replaced by a copy of the 32-bit 'masked' register,
so this patch does not affect the size of msi_desc.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

MSI interrupts have a mask_pos where MSI-X have a mask_base.  Use a
transparent union to get rid of some ugly casts.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

By changing from a 5-bit field to a 1-bit field, we free up some bits
that can be used by a later patch.  Also rearrange the fields for better
packing on 64-bit platforms (reducing the size of msi_desc from 72 bytes
to 64 bytes).

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Impact: simplify code

Pass irq_desc and cfg around, instead of raw IRQ numbers - this way
we dont have to look it up again and again.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

[PATCH 1/2] pci/irq: restore mask_bits in msi shutdown -v3

Yinghai found that kexec'ing a RHEL 5.1 kernel with 2.6.25-rc3+ kernels
prevents his NIC from working.  He bisected to

| commit 89d694b9dbe769ca1004e01db0ca43964806a611
| Author: Thomas Gleixner <tglx@linutronix.de>
| Date:   Mon Feb 18 18:25:17 2008 +0100
|
|   genirq: do not leave interupts enabled on free_irq
|
|   The default_disable() function was changed in commit:
|
|    76d2160147f43f982dfe881404cfde9fd0a9da21
|    genirq: do not mask interrupts by default
|

For MSI, default_shutdown will call mask_bit for msi device.  All mask bits
will left disabled after free_irq.  Then in the kexec case, the next kernel
can only use msi_enable bit, so all device's MSI can not be used.

So lets to restore the mask bit to its pci reset defined value (enabled) when
we disable the kernels use of msi to be a little friendlier to kexec'd kernels.

Extend msi_set_mask_bit to msi_set_mask_bits to take mask, so we can fully
restore that to 0x00 instead of 0xfe.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Jesse Barnes <jbarnes@hobbes.lan>

This patch introduces an optional function, arch_teardown_msi_irqs(),
which gives an arch the opportunity to do per-device teardown for
MSI/X. If that's not required, the default version simply calls
arch_teardown_msi_irq() for each msi irq required.

arch_teardown_msi_irqs() is simply passed a pdev, attached to the pdev
is a list of msi_descs, it is up to the arch to free the irq associated
with each of these as appropriate.

For archs that _don't_ implement arch_teardown_msi_irqs(), all msi_descs
with irq == 0 are considered unallocated, and the arch teardown routine
is not called on them.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

This patch introduces an optional function, arch_setup_msi_irqs(),
(note the plural) which gives an arch the opportunity to do per-device
setup for MSI/X and then allocate all the requested MSI/Xs at once.

If that's not required by the arch, the default version simply calls
arch_setup_msi_irq() for each MSI irq required.

arch_setup_msi_irqs() is passed a pdev, attached to the pdev is a list
of msi_descs with irq == 0, it is up to the arch to connect these up to
an irq (via set_irq_msi()) or return an error. For convenience the number
of vectors and the type are passed also.

All msi_descs with irq != 0 are considered allocated, and the arch
teardown routine will be called on them when necessary.

The existing semantics of pci_enable_msix() are that if the requested
number of irqs can not be allocated, the maximum number that _could_ be
allocated is returned. To support that, we define that in case of an
error from arch_setup_msi_irqs(), the number of msi_descs with irq != 0
are considered allocated, and are counted toward the "max that could be
allocated".


Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

The msi descriptors are linked together with what looks a lot like
a linked list, but isn't a struct list_head list. Make it one.

The only complication is that previously we walked a list of irqs, and
got the descriptor for each with get_irq_msi(). Now we have a list of
descriptors and need to get the irq out of it, so it needs to be in the
actual struct msi_desc. We use 0 to indicate no irq is setup.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Add an arch_check_device(), which gives archs a chance to check the input
to pci_enable_msi/x. The arch might be interested in the value of nvec so
pass it in. Propagate the error value returned from the arch routine out
to the caller.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>