[PATCH v2 4/7] irqchip: Have CONFIG_IRQ_MSI_IOMMU be selected by irqchips that need it

[Nicolin Chen]

From: Jason Gunthorpe <jgg@xxxxxxxxxx>

Currently, IRQ_MSI_IOMMU is selected if DMA_IOMMU is available to provide
an implementation for iommu_dma_prepare/compose_msi_msg(). However, it'll
make more sense for irqchips that call prepare/compose to select it, and
that will trigger all the additional code and data to be compiled into
the kernel.

If IRQ_MSI_IOMMU is selected with no IOMMU side implementation, then the
prepare/compose() will be NOP stubs.

If IRQ_MSI_IOMMU is not selected by an irqchip, then the related code on
the iommu side is compiled out.

Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
 drivers/iommu/Kconfig   | 1 -
 drivers/irqchip/Kconfig | 4 ++++
 kernel/irq/Kconfig      | 1 +
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index ec1b5e32b972..5124e7431fe3 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -154,7 +154,6 @@ config IOMMU_DMA
 	select DMA_OPS_HELPERS
 	select IOMMU_API
 	select IOMMU_IOVA
-	select IRQ_MSI_IOMMU
 	select NEED_SG_DMA_LENGTH
 	select NEED_SG_DMA_FLAGS if SWIOTLB
 
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index c11b9965c4ad..64658a1c3aa1 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -28,6 +28,7 @@ config ARM_GIC_V2M
 	select ARM_GIC
 	select IRQ_MSI_LIB
 	select PCI_MSI
+	select IRQ_MSI_IOMMU
 
 config GIC_NON_BANKED
 	bool
@@ -38,12 +39,14 @@ config ARM_GIC_V3
 	select PARTITION_PERCPU
 	select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
 	select HAVE_ARM_SMCCC_DISCOVERY
+	select IRQ_MSI_IOMMU
 
 config ARM_GIC_V3_ITS
 	bool
 	select GENERIC_MSI_IRQ
 	select IRQ_MSI_LIB
 	default ARM_GIC_V3
+	select IRQ_MSI_IOMMU
 
 config ARM_GIC_V3_ITS_FSL_MC
 	bool
@@ -408,6 +411,7 @@ config LS_EXTIRQ
 
 config LS_SCFG_MSI
 	def_bool y if SOC_LS1021A || ARCH_LAYERSCAPE
+	select IRQ_MSI_IOMMU
 	depends on PCI_MSI
 
 config PARTITION_PERCPU
diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig
index 5432418c0fea..9636aed20401 100644
--- a/kernel/irq/Kconfig
+++ b/kernel/irq/Kconfig
@@ -100,6 +100,7 @@ config GENERIC_MSI_IRQ
 	bool
 	select IRQ_DOMAIN_HIERARCHY
 
+# irqchip drivers should select this if they call iommu_dma_prepare_msi()
 config IRQ_MSI_IOMMU
 	bool
 
-- 
2.43.0