[10/15] cxl: Add preliminary workaround for CX4 interrupt limitation

[Michael Ellerman]

On Wed, 2016-13-07 at 21:17:09 UTC, Ian Munsie wrote:
> From: Ian Munsie <imunsie at au1.ibm.com>
> 
> The Mellanox CX4 has a hardware limitation where only 4 bits of the
> AFU interrupt number can be passed to the XSL when sending an interrupt,
> limiting it to only 15 interrupts per context (AFU interrupt number 0 is
> invalid).
> 
> In order to overcome this, we will allocate additional contexts linked
> to the default context as extra address space for the extra interrupts -
> this will be implemented in the next patch.
> 
> This patch adds the preliminary support to allow this, by way of adding
> a linked list in the context structure that we use to keep track of the
> contexts dedicated to interrupts, and an API to simultaneously iterate
> over the related context structures, AFU interrupt numbers and hardware
> interrupt numbers. The point of using a single API to iterate these is
> to hide some of the details of the iteration from external code, and to
> reduce the number of APIs that need to be exported via base.c to allow
> built in code to call.
> 
> Signed-off-by: Ian Munsie <imunsie at au1.ibm.com>
> Reviewed-by: Frederic Barrat <fbarrat at linux.vnet.ibm.com>
> Reviewed-by: Andrew Donnellan <andrew.donnellan at au1.ibm.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/cbce0917e2e47d4bf5aa3b5fd6

cheers