Messages in this thread | | | From | Marc Zyngier <> | Subject | [PATCH 0/7] Level-triggered MSI support | Date | Mon, 23 Apr 2018 11:34:33 +0100 |
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This series is a first shot at teaching the kernel about the oxymoron expressed in $SUBJECT. Over the past couple of years, we've seen some SoCs coming up with ways of signalling level interrupts using a new flavor of MSIs, where the MSI controller uses two distinct messages: one that raises a virtual line, and one that lowers it. The target MSI controller is in charge of maintaining the state of the line.
This allows for a much simplified HW signal routing (no need to have hundreds of discrete lines to signal level interrupts if you already have a memory bus), but results in a departure from the current idea the kernel has of MSIs.
This series takes a minimal approach to the problem, which is to allow MSI controllers to use not only one, but up to two messages at a time. This is controlled by a flag exposed at MSI irq domain creation, and is only supported with platform MSI.
The rest of the series repaints the Marvell ICU/GICP drivers which already make use of this feature with a side-channel, and adds support for the same feature in GICv3. A side effect of the last GICv3 patch is that you can also use SPIs to signal PCI MSIs. This is a last resort measure for SoCs where the ITS is unusable for unspeakable reasons.
Marc Zyngier (7): genirq/msi: Allow level-triggered MSIs to be exposed by MSI providers genirq/msi: Limit level-triggered MSI to platform devices irqchip/mvebu-gicp: Use level-triggered MSIs between ICU and GICP dma-iommu: Fix compilation when !CONFIG_IOMMU_DMA irqchip/gic-v3: Add support for Message Based Interrupts as an MSI controller irqchip/gic-v3: Add PCI/MSI support to the GICv3 MBI sub-driver dt-bindings/gic-v3: Add documentation for MBI support
.../bindings/interrupt-controller/arm,gic-v3.txt | 17 + drivers/base/platform-msi.c | 3 + drivers/irqchip/Makefile | 2 +- drivers/irqchip/irq-gic-v3-mbi.c | 343 +++++++++++++++++++++ drivers/irqchip/irq-gic-v3.c | 6 + drivers/irqchip/irq-mvebu-gicp.c | 37 +-- drivers/irqchip/irq-mvebu-gicp.h | 12 - drivers/irqchip/irq-mvebu-icu.c | 33 +- drivers/pci/msi.c | 3 + include/linux/dma-iommu.h | 1 + include/linux/irqchip/arm-gic-v3.h | 1 + include/linux/msi.h | 2 + kernel/irq/msi.c | 32 +- 13 files changed, 427 insertions(+), 65 deletions(-) create mode 100644 drivers/irqchip/irq-gic-v3-mbi.c delete mode 100644 drivers/irqchip/irq-mvebu-gicp.h
-- 2.14.2
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