irqchip: Add Loongson Extended I/O interrupt controller support

EIOINTC stands for "Extended I/O Interrupts" that described in Section
11.2 of "Loongson 3A5000 Processor Reference Manual". For more
information please refer Documentation/loongarch/irq-chip-model.rst.

Loongson-3A5000 has 4 cores per NUMA node, and each NUMA node has an
EIOINTC; while Loongson-3C5000 has 16 cores per NUMA node, and each NUMA
node has 4 EIOINTCs. In other words, 16 cores of one NUMA node in
Loongson-3C5000 are organized in 4 groups, each group connects to an
EIOINTC. We call the "group" here as an EIOINTC node, so each EIOINTC
node always includes 4 cores (both in Loongson-3A5000 and Loongson-
3C5000).
Co-developed-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1658314292-35346-12-git-send-email-lvjianmin@loongson.cn

arch/loongarch/include/asm/irq.h

@@ -87,15 +87,6 @@ extern struct acpi_vector_group msi_group[MAX_IO_PICS];
 extern int find_pch_pic(u32 gsi);
 extern int eiointc_get_node(int id);
 
-static inline void eiointc_enable(void)
-{
-	uint64_t misc;
-
-	misc = iocsr_read64(LOONGARCH_IOCSR_MISC_FUNC);
-	misc |= IOCSR_MISC_FUNC_EXT_IOI_EN;
-	iocsr_write64(misc, LOONGARCH_IOCSR_MISC_FUNC);
-}
-
 struct acpi_madt_lio_pic;
 struct acpi_madt_eio_pic;
 struct acpi_madt_ht_pic;
@@ -107,7 +98,7 @@ struct irq_domain *loongarch_cpu_irq_init(void);
 
 int liointc_acpi_init(struct irq_domain *parent,
 					struct acpi_madt_lio_pic *acpi_liointc);
-struct irq_domain *eiointc_acpi_init(struct irq_domain *parent,
+int eiointc_acpi_init(struct irq_domain *parent,
 					struct acpi_madt_eio_pic *acpi_eiointc);
 
 struct irq_domain *htvec_acpi_init(struct irq_domain *parent,

drivers/irqchip/Kconfig

@@ -555,6 +555,16 @@ config LOONGSON_LIOINTC
 	help
 	  Support for the Loongson Local I/O Interrupt Controller.
 
+config LOONGSON_EIOINTC
+	bool "Loongson Extend I/O Interrupt Controller"
+	depends on LOONGARCH
+	depends on MACH_LOONGSON64
+	default MACH_LOONGSON64
+	select IRQ_DOMAIN_HIERARCHY
+	select GENERIC_IRQ_CHIP
+	help
+	  Support for the Loongson3 Extend I/O Interrupt Vector Controller.
+
 config LOONGSON_HTPIC
 	bool "Loongson3 HyperTransport PIC Controller"
 	depends on MACH_LOONGSON64 && MIPS

drivers/irqchip/Makefile

@@ -104,6 +104,7 @@ obj-$(CONFIG_TI_SCI_INTR_IRQCHIP)	+= irq-ti-sci-intr.o
 obj-$(CONFIG_TI_SCI_INTA_IRQCHIP)	+= irq-ti-sci-inta.o
 obj-$(CONFIG_TI_PRUSS_INTC)		+= irq-pruss-intc.o
 obj-$(CONFIG_LOONGSON_LIOINTC)		+= irq-loongson-liointc.o
+obj-$(CONFIG_LOONGSON_EIOINTC)		+= irq-loongson-eiointc.o
 obj-$(CONFIG_LOONGSON_HTPIC)		+= irq-loongson-htpic.o
 obj-$(CONFIG_LOONGSON_HTVEC)		+= irq-loongson-htvec.o
 obj-$(CONFIG_LOONGSON_PCH_PIC)		+= irq-loongson-pch-pic.o

include/linux/cpuhotplug.h

@@ -151,6 +151,7 @@ enum cpuhp_state {
 	CPUHP_AP_IRQ_BCM2836_STARTING,
 	CPUHP_AP_IRQ_MIPS_GIC_STARTING,
 	CPUHP_AP_IRQ_RISCV_STARTING,
+	CPUHP_AP_IRQ_LOONGARCH_STARTING,
 	CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
 	CPUHP_AP_ARM_MVEBU_COHERENCY,
 	CPUHP_AP_MICROCODE_LOADER,