From cbce0917e2e47d4bf5aa3b5fd6b1247f33e1a126 Mon Sep 17 00:00:00 2001 From: Ian Munsie Date: Thu, 14 Jul 2016 07:17:09 +1000 Subject: cxl: Add preliminary workaround for CX4 interrupt limitation 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 Reviewed-by: Frederic Barrat Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman --- include/misc/cxl.h | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'include/misc') diff --git a/include/misc/cxl.h b/include/misc/cxl.h index fc07ed47c2d8..6c52cbcdfd79 100644 --- a/include/misc/cxl.h +++ b/include/misc/cxl.h @@ -177,6 +177,15 @@ int cxl_process_element(struct cxl_context *ctx); int cxl_set_max_irqs_per_process(struct pci_dev *dev, int irqs); int cxl_get_max_irqs_per_process(struct pci_dev *dev); +/* + * Use to simultaneously iterate over hardware interrupt numbers, contexts and + * afu interrupt numbers allocated for the device via pci_enable_msix_range and + * is a useful convenience function when working with hardware that has + * limitations on the number of interrupts per process. *ctx and *afu_irq + * should be NULL and 0 to start the iteration. + */ +int cxl_next_msi_hwirq(struct pci_dev *pdev, struct cxl_context **ctx, int *afu_irq); + /* * These calls allow drivers to create their own file descriptors and make them * identical to the cxl file descriptor user API. An example use case: -- cgit v1.2.3-59-g8ed1b