irqchip/gic-v3: Rename GICv3 ITS MSI parent

The GICv5 ITS will reuse some GICv3 ITS MSI parent functions therefore
it makes sense to keep the code functionality in a compilation unit
shared by the two drivers.

Rename the GICv3 ITS MSI parent file and update the related
Kconfig/Makefile entries to pave the way for code sharing.

Signed-off-by: Lorenzo Pieralisi <[e-mail]>
Reviewed-by: Marc Zyngier <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Marc Zyngier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Marc Zyngier <[e-mail]>

drivers/irqchip/Kconfig

···
 	select HAVE_ARM_SMCCC_DISCOVERY
 	select IRQ_MSI_IOMMU
 
+config ARM_GIC_ITS_PARENT
+	bool
+
 config ARM_GIC_V3_ITS
 	bool
 	select GENERIC_MSI_IRQ
 	select IRQ_MSI_LIB
+	select ARM_GIC_ITS_PARENT
 	default ARM_GIC_V3
 	select IRQ_MSI_IOMMU
 

drivers/irqchip/Makefile

···
 obj-$(CONFIG_IRQ_MSI_LIB)		+= irq-msi-lib.o
 obj-$(CONFIG_ARM_GIC_V2M)		+= irq-gic-v2m.o
 obj-$(CONFIG_ARM_GIC_V3)		+= irq-gic-v3.o irq-gic-v3-mbi.o irq-gic-common.o
-obj-$(CONFIG_ARM_GIC_V3_ITS)		+= irq-gic-v3-its.o irq-gic-v4.o irq-gic-v3-its-msi-parent.o
+obj-$(CONFIG_ARM_GIC_ITS_PARENT)	+= irq-gic-its-msi-parent.o
+obj-$(CONFIG_ARM_GIC_V3_ITS)		+= irq-gic-v3-its.o irq-gic-v4.o
 obj-$(CONFIG_ARM_GIC_V3_ITS_FSL_MC)	+= irq-gic-v3-its-fsl-mc-msi.o
 obj-$(CONFIG_PARTITION_PERCPU)		+= irq-partition-percpu.o
 obj-$(CONFIG_ARM_GIC_V5)		+= irq-gic-v5.o irq-gic-v5-irs.o

drivers/irqchip/irq-gic-common.h

···
 void gic_enable_of_quirks(const struct device_node *np,
 			  const struct gic_quirk *quirks, void *data);
 
-extern const struct msi_parent_ops gic_v3_its_msi_parent_ops;
-
 #define RDIST_FLAGS_PROPBASE_NEEDS_FLUSHING    (1 << 0)
 #define RDIST_FLAGS_RD_TABLES_PREALLOCATED     (1 << 1)
 #define RDIST_FLAGS_FORCE_NON_SHAREABLE        (1 << 2)

drivers/irqchip/irq-gic-its-msi-parent.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024 ARM Limited, All Rights Reserved.
+ */
+
+#ifndef _IRQ_GIC_ITS_MSI_PARENT_H
+#define _IRQ_GIC_ITS_MSI_PARENT_H
+
+extern const struct msi_parent_ops gic_v3_its_msi_parent_ops;
+
+#endif /* _IRQ_GIC_ITS_MSI_PARENT_H */

drivers/irqchip/irq-gic-v3-its-msi-parent.c drivers/irqchip/irq-gic-its-msi-parent.c

···
 #include <linux/acpi_iort.h>
 #include <linux/pci.h>
 
-#include "irq-gic-common.h"
+#include "irq-gic-its-msi-parent.h"
 #include <linux/irqchip/irq-msi-lib.h>
 
 #define ITS_MSI_FLAGS_REQUIRED  (MSI_FLAG_USE_DEF_DOM_OPS |	\

drivers/irqchip/irq-gic-v3-its.c

···
 #include <asm/exception.h>
 
 #include "irq-gic-common.h"
+#include "irq-gic-its-msi-parent.h"
 #include <linux/irqchip/irq-msi-lib.h>
 
 #define ITS_FLAGS_CMDQ_NEEDS_FLUSHING		(1ULL << 0)