irqchip / ACPI: Introduce ACPI_IRQ_MODEL_LPIC for LoongArch

For LoongArch, ACPI_IRQ_MODEL_LPIC is introduced, and then the
callback acpi_get_gsi_domain_id and acpi_gsi_to_irq_fallback are
implemented.

The acpi_get_gsi_domain_id callback returns related fwnode handle
of irqdomain for different GSI range.

The acpi_gsi_to_irq_fallback will create new mapping for gsi when
the mapping of it is not found.
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1658314292-35346-14-git-send-email-lvjianmin@loongson.cn

drivers/acpi/bus.c

@@ -1145,6 +1145,9 @@ static int __init acpi_bus_init_irq(void)
 	case ACPI_IRQ_MODEL_PLATFORM:
 		message = "platform specific model";
 		break;
+	case ACPI_IRQ_MODEL_LPIC:
+		message = "LPIC";
+		break;
 	default:
 		pr_info("Unknown interrupt routing model\n");
 		return -ENODEV;

drivers/irqchip/irq-loongarch-cpu.c

@@ -16,6 +16,41 @@
 static struct irq_domain *irq_domain;
 struct fwnode_handle *cpuintc_handle;
 
+static u32 lpic_gsi_to_irq(u32 gsi)
+{
+	/* Only pch irqdomain transferring is required for LoongArch. */
+	if (gsi >= GSI_MIN_PCH_IRQ && gsi <= GSI_MAX_PCH_IRQ)
+		return acpi_register_gsi(NULL, gsi, ACPI_LEVEL_SENSITIVE, ACPI_ACTIVE_HIGH);
+
+	return 0;
+}
+
+static struct fwnode_handle *lpic_get_gsi_domain_id(u32 gsi)
+{
+	int id;
+	struct fwnode_handle *domain_handle = NULL;
+
+	switch (gsi) {
+	case GSI_MIN_CPU_IRQ ... GSI_MAX_CPU_IRQ:
+		if (liointc_handle)
+			domain_handle = liointc_handle;
+		break;
+
+	case GSI_MIN_LPC_IRQ ... GSI_MAX_LPC_IRQ:
+		if (pch_lpc_handle)
+			domain_handle = pch_lpc_handle;
+		break;
+
+	case GSI_MIN_PCH_IRQ ... GSI_MAX_PCH_IRQ:
+		id = find_pch_pic(gsi);
+		if (id >= 0 && pch_pic_handle[id])
+			domain_handle = pch_pic_handle[id];
+		break;
+	}
+
+	return domain_handle;
+}
+
 static void mask_loongarch_irq(struct irq_data *d)
 {
 	clear_csr_ecfg(ECFGF(d->hwirq));
@@ -102,6 +137,8 @@ static int __init cpuintc_acpi_init(union acpi_subtable_headers *header,
 		panic("Failed to add irqdomain for LoongArch CPU");
 
 	set_handle_irq(&handle_cpu_irq);
+	acpi_set_irq_model(ACPI_IRQ_MODEL_LPIC, lpic_get_gsi_domain_id);
+	acpi_set_gsi_to_irq_fallback(lpic_gsi_to_irq);
 	acpi_cascade_irqdomain_init();
 
 	return 0;

include/linux/acpi.h

@@ -105,6 +105,7 @@ enum acpi_irq_model_id {
 	ACPI_IRQ_MODEL_IOSAPIC,
 	ACPI_IRQ_MODEL_PLATFORM,
 	ACPI_IRQ_MODEL_GIC,
+	ACPI_IRQ_MODEL_LPIC,
 	ACPI_IRQ_MODEL_COUNT
 };