irqchip: Add LoongArch CPU interrupt controller support

LoongArch CPUINTC stands for CSR.ECFG/CSR.ESTAT and related interrupt
controller that described in Section 7.4 of "LoongArch Reference Manual,
Vol 1". For more information please refer Documentation/loongarch/irq-
chip-model.rst.

LoongArch CPUINTC has 13 interrupt sources: SWI0~1, HWI0~7, IPI, TI
(Timer) and PCOV (PMC). IRQ mappings of HWI0~7 are configurable (can be
created from DT/ACPI), but IPI, TI (Timer) and PCOV (PMC) are hardcoded
bits, so we expose the fwnode_handle to map them, and get mapped irq
by irq_create_mapping when using them.

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/1658314292-35346-13-git-send-email-lvjianmin@loongson.cn

arch/loongarch/include/asm/irq.h

@@ -35,9 +35,6 @@ static inline bool on_irq_stack(int cpu, unsigned long sp)
 	return (low <= sp && sp <= high);
 }
 
-int get_ipi_irq(void);
-int get_pmc_irq(void);
-int get_timer_irq(void);
 void spurious_interrupt(void);
 
 #define NR_IRQS_LEGACY 16
@@ -94,8 +91,6 @@ struct acpi_madt_bio_pic;
 struct acpi_madt_msi_pic;
 struct acpi_madt_lpc_pic;
 
-struct irq_domain *loongarch_cpu_irq_init(void);
-
 int liointc_acpi_init(struct irq_domain *parent,
 					struct acpi_madt_lio_pic *acpi_liointc);
 int eiointc_acpi_init(struct irq_domain *parent,
@@ -128,7 +123,7 @@ extern struct acpi_madt_lpc_pic *acpi_pchlpc;
 extern struct acpi_madt_msi_pic *acpi_pchmsi[MAX_IO_PICS];
 extern struct acpi_madt_bio_pic *acpi_pchpic[MAX_IO_PICS];
 
-extern struct irq_domain *cpu_domain;
+extern struct fwnode_handle *cpuintc_handle;
 extern struct fwnode_handle *liointc_handle;
 extern struct fwnode_handle *pch_lpc_handle;
 extern struct fwnode_handle *pch_pic_handle[MAX_IO_PICS];

arch/loongarch/kernel/irq.c

@@ -25,8 +25,6 @@ DEFINE_PER_CPU(unsigned long, irq_stack);
 DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
 EXPORT_PER_CPU_SYMBOL(irq_stat);
 
-struct irq_domain *cpu_domain;
-
 struct acpi_vector_group pch_group[MAX_IO_PICS];
 struct acpi_vector_group msi_group[MAX_IO_PICS];
 /*
@@ -89,6 +87,16 @@ static void __init init_vec_parent_group(void)
 	acpi_table_parse(ACPI_SIG_MCFG, early_pci_mcfg_parse);
 }
 
+static int __init get_ipi_irq(void)
+{
+	struct irq_domain *d = irq_find_matching_fwnode(cpuintc_handle, DOMAIN_BUS_ANY);
+
+	if (d)
+		return irq_create_mapping(d, EXCCODE_IPI - EXCCODE_INT_START);
+
+	return -EINVAL;
+}
+
 void __init init_IRQ(void)
 {
 	int i;
@@ -105,7 +113,9 @@ void __init init_IRQ(void)
 	init_vec_parent_group();
 	irqchip_init();
 #ifdef CONFIG_SMP
-	ipi_irq = EXCCODE_IPI - EXCCODE_INT_START;
+	ipi_irq = get_ipi_irq();
+	if (ipi_irq < 0)
+		panic("IPI IRQ mapping failed\n");
 	irq_set_percpu_devid(ipi_irq);
 	r = request_percpu_irq(ipi_irq, loongson3_ipi_interrupt, "IPI", &ipi_dummy_dev);
 	if (r < 0)

arch/loongarch/kernel/time.c

@@ -123,6 +123,16 @@ void sync_counter(void)
 	csr_write64(-init_timeval, LOONGARCH_CSR_CNTC);
 }
 
+static int get_timer_irq(void)
+{
+	struct irq_domain *d = irq_find_matching_fwnode(cpuintc_handle, DOMAIN_BUS_ANY);
+
+	if (d)
+		return irq_create_mapping(d, EXCCODE_TIMER - EXCCODE_INT_START);
+
+	return -EINVAL;
+}
+
 int constant_clockevent_init(void)
 {
 	unsigned int irq;
@@ -132,7 +142,9 @@ int constant_clockevent_init(void)
 	struct clock_event_device *cd;
 	static int timer_irq_installed = 0;
 
-	irq = EXCCODE_TIMER - EXCCODE_INT_START;
+	irq = get_timer_irq();
+	if (irq < 0)
+		pr_err("Failed to map irq %d (timer)\n", irq);
 
 	cd = &per_cpu(constant_clockevent_device, cpu);
 

drivers/irqchip/Kconfig

@@ -546,6 +546,16 @@ config EXYNOS_IRQ_COMBINER
 	  Say yes here to add support for the IRQ combiner devices embedded
 	  in Samsung Exynos chips.
 
+config IRQ_LOONGARCH_CPU
+	bool
+	select GENERIC_IRQ_CHIP
+	select IRQ_DOMAIN
+	select GENERIC_IRQ_EFFECTIVE_AFF_MASK
+	help
+	  Support for the LoongArch CPU Interrupt Controller. For details of
+	  irq chip hierarchy on LoongArch platforms please read the document
+	  Documentation/loongarch/irq-chip-model.rst.
+
 config LOONGSON_LIOINTC
 	bool "Loongson Local I/O Interrupt Controller"
 	depends on MACH_LOONGSON64

drivers/irqchip/Makefile

@@ -103,6 +103,7 @@ obj-$(CONFIG_LS1X_IRQ)			+= irq-ls1x.o
 obj-$(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-$(CONFIG_IRQ_LOONGARCH_CPU)		+= irq-loongarch-cpu.o
 obj-$(CONFIG_LOONGSON_LIOINTC)		+= irq-loongson-liointc.o
 obj-$(CONFIG_LOONGSON_EIOINTC)		+= irq-loongson-eiointc.o
 obj-$(CONFIG_LOONGSON_HTPIC)		+= irq-loongson-htpic.o

drivers/irqchip/irq-loongarch-cpu.c

@@ -0,0 +1,111 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqchip.h>
+#include <linux/irqdomain.h>
+
+#include <asm/loongarch.h>
+#include <asm/setup.h>
+
+static struct irq_domain *irq_domain;
+struct fwnode_handle *cpuintc_handle;
+
+static void mask_loongarch_irq(struct irq_data *d)
+{
+	clear_csr_ecfg(ECFGF(d->hwirq));
+}
+
+static void unmask_loongarch_irq(struct irq_data *d)
+{
+	set_csr_ecfg(ECFGF(d->hwirq));
+}
+
+static struct irq_chip cpu_irq_controller = {
+	.name		= "CPUINTC",
+	.irq_mask	= mask_loongarch_irq,
+	.irq_unmask	= unmask_loongarch_irq,
+};
+
+static void handle_cpu_irq(struct pt_regs *regs)
+{
+	int hwirq;
+	unsigned int estat = read_csr_estat() & CSR_ESTAT_IS;
+
+	while ((hwirq = ffs(estat))) {
+		estat &= ~BIT(hwirq - 1);
+		generic_handle_domain_irq(irq_domain, hwirq - 1);
+	}
+}
+
+static int loongarch_cpu_intc_map(struct irq_domain *d, unsigned int irq,
+			     irq_hw_number_t hwirq)
+{
+	irq_set_noprobe(irq);
+	irq_set_chip_and_handler(irq, &cpu_irq_controller, handle_percpu_irq);
+
+	return 0;
+}
+
+static const struct irq_domain_ops loongarch_cpu_intc_irq_domain_ops = {
+	.map = loongarch_cpu_intc_map,
+	.xlate = irq_domain_xlate_onecell,
+};
+
+static int __init
+liointc_parse_madt(union acpi_subtable_headers *header,
+		       const unsigned long end)
+{
+	struct acpi_madt_lio_pic *liointc_entry = (struct acpi_madt_lio_pic *)header;
+
+	return liointc_acpi_init(irq_domain, liointc_entry);
+}
+
+static int __init
+eiointc_parse_madt(union acpi_subtable_headers *header,
+		       const unsigned long end)
+{
+	struct acpi_madt_eio_pic *eiointc_entry = (struct acpi_madt_eio_pic *)header;
+
+	return eiointc_acpi_init(irq_domain, eiointc_entry);
+}
+
+static int __init acpi_cascade_irqdomain_init(void)
+{
+	acpi_table_parse_madt(ACPI_MADT_TYPE_LIO_PIC,
+			      liointc_parse_madt, 0);
+	acpi_table_parse_madt(ACPI_MADT_TYPE_EIO_PIC,
+			      eiointc_parse_madt, 0);
+	return 0;
+}
+
+static int __init cpuintc_acpi_init(union acpi_subtable_headers *header,
+				   const unsigned long end)
+{
+	if (irq_domain)
+		return 0;
+
+	/* Mask interrupts. */
+	clear_csr_ecfg(ECFG0_IM);
+	clear_csr_estat(ESTATF_IP);
+
+	cpuintc_handle = irq_domain_alloc_fwnode(NULL);
+	irq_domain = irq_domain_create_linear(cpuintc_handle, EXCCODE_INT_NUM,
+					&loongarch_cpu_intc_irq_domain_ops, NULL);
+
+	if (!irq_domain)
+		panic("Failed to add irqdomain for LoongArch CPU");
+
+	set_handle_irq(&handle_cpu_irq);
+	acpi_cascade_irqdomain_init();
+
+	return 0;
+}
+
+IRQCHIP_ACPI_DECLARE(cpuintc_v1, ACPI_MADT_TYPE_CORE_PIC,
+		NULL, ACPI_MADT_CORE_PIC_VERSION_V1, cpuintc_acpi_init);