There are plans afoot to use pci_restore_msi_state() to restore MSI
state after a device reset. In order for this to work for the RTAS MSI
backend, we need to read back the MSI message from config space after
it has been setup by firmware.
This should be sufficient for restoring the MSI state after a device
reset, however we will need to revisit this for suspend to disk if that
is ever implemented on pseries.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Currently rtas_change_msi() returns either the error code from RTAS, or if
the RTAS call succeeded the number of irqs that were configured by RTAS.
This makes checking the return value more complicated than it needs to be.
Instead, have rtas_change_msi() check that the number of irqs configured by
RTAS is equal to what we requested - and return an error otherwise. This makes
the return semantics match the usual 0 for success, something else for error.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
rtas_setup_msi_irqs() doesn't need to call teardown() itself, the
generic code will do this for us as long as we return a non-zero
value.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Implement MSI support via RTAS (RTAS = run-time firmware on pSeries
machines). For now we assumes that if the required RTAS tokens for
MSI are present, then we want to use the RTAS MSI routines.
When RTAS is managing MSIs for us, it will/may enable MSI on devices that
support it by default. This is contrary to the Linux model where a device
is in LSI mode until the driver requests MSIs.
To remedy this we add a pci_irq_fixup call, which disables MSI if they've
been assigned by firmware and the device also supports LSI. Devices that
don't support LSI at all will be left as is, drivers are still expected
to call pci_enable_msi() before using the device.
At the moment there is no pci_irq_fixup on pSeries, so we can just set it
unconditionally. If other platforms use the RTAS MSI backend they'll need
to check that still holds.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
