[PATCH RFC 02/10] irqchip: Add LoongArch CPU interrupt controller support

[Jianmin Lv <lvjianmin@loongson.cn>]

We are preparing to add new Loongson (based on LoongArch, not compatible
with old MIPS-based Loongson) support. This patch add the 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 define get_xxx_irq() for them.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
---
 drivers/irqchip/Kconfig                    |  10 +++
 drivers/irqchip/Makefile                   |   1 +
 drivers/irqchip/irq-loongarch-cpu.c        | 134 +++++++++++++++++++++++++++++
 drivers/irqchip/irq-loongarch-pic-common.c |  66 ++++++++++++++
 drivers/irqchip/irq-loongarch-pic-common.h |  22 +++++
 5 files changed, 233 insertions(+)
 create mode 100644 drivers/irqchip/irq-loongarch-cpu.c
 create mode 100644 drivers/irqchip/irq-loongarch-pic-common.c
 create mode 100644 drivers/irqchip/irq-loongarch-pic-common.h

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 39d6be2..a596ee7 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -545,6 +545,16 @@ 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
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 160a1d8..736f030 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -105,6 +105,7 @@ 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-$(CONFIG_IRQ_LOONGARCH_CPU)		+= irq-loongarch-cpu.o irq-loongarch-pic-common.o
 obj-$(CONFIG_LOONGSON_LIOINTC)		+= irq-loongson-liointc.o
 obj-$(CONFIG_LOONGSON_HTPIC)		+= irq-loongson-htpic.o
 obj-$(CONFIG_LOONGSON_HTVEC)		+= irq-loongson-htvec.o
diff --git a/drivers/irqchip/irq-loongarch-cpu.c b/drivers/irqchip/irq-loongarch-cpu.c
new file mode 100644
index 0000000..b1f12f5
--- /dev/null
+++ b/drivers/irqchip/irq-loongarch-cpu.c
@@ -0,0 +1,134 @@
+// 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>
+#include "irq-loongarch-pic-common.h"
+
+static struct irq_domain *irq_domain;
+
+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		= "LoongArch",
+	.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);
+	}
+}
+
+int get_ipi_irq(void)
+{
+	return irq_create_mapping(irq_domain, EXCCODE_IPI - EXCCODE_INT_START);
+}
+
+int get_pmc_irq(void)
+{
+	return irq_create_mapping(irq_domain, EXCCODE_PMC - EXCCODE_INT_START);
+}
+
+int get_timer_irq(void)
+{
+	return irq_create_mapping(irq_domain, EXCCODE_TIMER - EXCCODE_INT_START);
+}
+
+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,
+};
+
+struct irq_domain * __init loongarch_cpu_irq_init(void)
+{
+	struct fwnode_handle *domain_handle;
+
+	/* Mask interrupts. */
+	clear_csr_ecfg(ECFG0_IM);
+	clear_csr_estat(ESTATF_IP);
+
+	domain_handle = irq_domain_alloc_fwnode(NULL);
+	irq_domain = irq_domain_create_linear(domain_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);
+
+	return irq_domain;
+}
+#ifdef CONFIG_ACPI
+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 coreintc_acpi_init_v1(union acpi_subtable_headers *header,
+				   const unsigned long end)
+{
+	if (irq_domain)
+		return 0;
+
+	init_vector_parent_group();
+	loongarch_cpu_irq_init();
+	acpi_cascade_irqdomain_init();
+	return 0;
+}
+IRQCHIP_ACPI_DECLARE(coreintc_v1, ACPI_MADT_TYPE_CORE_PIC,
+		NULL, ACPI_MADT_CORE_PIC_VERSION_V1,
+		coreintc_acpi_init_v1);
+#endif
diff --git a/drivers/irqchip/irq-loongarch-pic-common.c b/drivers/irqchip/irq-loongarch-pic-common.c
new file mode 100644
index 0000000..1be544a
--- /dev/null
+++ b/drivers/irqchip/irq-loongarch-pic-common.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Loongson Limited, All Rights Reserved.
+ */
+
+#include <linux/irq.h>
+#include <linux/acpi.h>
+#include "irq-loongarch-pic-common.h"
+
+static struct acpi_vector_group vector_group[MAX_IO_PICS];
+
+static int pci_mcfg_parse(struct acpi_table_header *header)
+{
+	struct acpi_table_mcfg *mcfg;
+	struct acpi_mcfg_allocation *mptr;
+	int i, n;
+
+	if (header->length < sizeof(struct acpi_table_mcfg))
+		return -EINVAL;
+
+	n = (header->length - sizeof(struct acpi_table_mcfg)) /
+					sizeof(struct acpi_mcfg_allocation);
+	mcfg = (struct acpi_table_mcfg *)header;
+	mptr = (struct acpi_mcfg_allocation *) &mcfg[1];
+
+	for (i = 0; i < n; i++, mptr++)
+		vector_group[mptr->pci_segment].node = (mptr->address >> 44) & 0xf;
+
+	return 0;
+}
+
+void __init init_vector_parent_group(void)
+{
+	acpi_table_parse(ACPI_SIG_MCFG, pci_mcfg_parse);
+}
+
+void acpi_set_vector_parent(int node, struct irq_domain *parent)
+{
+	int i;
+
+	if (cpu_has_flatmode)
+		node = cpu_to_node(node * CORES_PER_EIO_NODE);
+
+	for (i = 0; i < MAX_IO_PICS; i++) {
+		if (node == vector_group[i].node) {
+			vector_group[i].parent = parent;
+			return;
+		}
+	}
+}
+
+struct irq_domain *acpi_get_msi_parent(int index)
+{
+	return vector_group[index].parent;
+}
+
+struct irq_domain *acpi_get_pch_parent(int node)
+{
+	int i;
+
+	for (i = 0; i < MAX_IO_PICS; i++) {
+		if (node == vector_group[i].node)
+			return vector_group[i].parent;
+	}
+	return NULL;
+}
diff --git a/drivers/irqchip/irq-loongarch-pic-common.h b/drivers/irqchip/irq-loongarch-pic-common.h
new file mode 100644
index 0000000..1844776
--- /dev/null
+++ b/drivers/irqchip/irq-loongarch-pic-common.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2022 Loongson Limited, All Rights Reserved.
+ */
+
+#ifndef _IRQ_LOONGARCH_PIC_COMMON_H
+#define _IRQ_LOONGARCH_PIC_COMMON_H
+
+#include <linux/of.h>
+#include <linux/irqdomain.h>
+
+struct acpi_vector_group {
+	int node;
+	struct irq_domain *parent;
+};
+
+void init_vector_parent_group(void);
+void acpi_set_vector_parent(int node, struct irq_domain *parent);
+struct irq_domain *acpi_get_msi_parent(int index);
+struct irq_domain *acpi_get_pch_parent(int node);
+
+#endif /* _IRQ_LOONGARCH_PIC_COMMON_H */
-- 
1.8.3.1