ACPI: RISC-V: Implement function to add implicit dependencies

RISC-V interrupt controllers for wired interrupts are platform devices
and hence their driver will be probed late. Also, APLIC which is one
such interrupt controller can not be probed early since it needs MSI
services. This needs a probing order between the interrupt controller
driver and the device drivers.

_DEP is typically used to indicate such dependencies. However, the
dependency may be already available like GSI mapping. Hence, instead of
an explicit _DEP, architecture can find the implicit dependencies and
add to the dependency list.

For RISC-V, add the dependencies for below use cases.

1) For devices which has IRQ resource, find out the interrupt controller
   using GSI number map and add the dependency.

2) For PCI host bridges:
        a) If _PRT indicate PCI link devices, add dependency on the link
           device.
        b) If _PRT indicates GSI, find out the interrupt controller
           using GSI number map and add the dependency.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://patch.msgid.link/20240812005929.113499-13-sunilvl@ventanamicro.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/riscv/irq.c

@@ -20,6 +20,12 @@ struct riscv_ext_intc_list {
 	struct list_head	list;
 };
 
+struct acpi_irq_dep_ctx {
+	int		rc;
+	unsigned int	index;
+	acpi_handle	handle;
+};
+
 LIST_HEAD(ext_intc_list);
 
 static int irqchip_cmp_func(const void *in0, const void *in1)
@@ -178,3 +184,152 @@ void __init riscv_acpi_init_gsi_mapping(void)
 	if (acpi_table_parse_madt(ACPI_MADT_TYPE_APLIC, riscv_acpi_aplic_parse_madt, 0) > 0)
 		acpi_get_devices("RSCV0002", riscv_acpi_create_gsi_map, NULL, NULL);
 }
+
+static acpi_handle riscv_acpi_get_gsi_handle(u32 gsi)
+{
+	struct riscv_ext_intc_list *ext_intc_element;
+	struct list_head *i;
+
+	list_for_each(i, &ext_intc_list) {
+		ext_intc_element = list_entry(i, struct riscv_ext_intc_list, list);
+		if (gsi >= ext_intc_element->gsi_base &&
+		    gsi < (ext_intc_element->gsi_base + ext_intc_element->nr_irqs))
+			return ext_intc_element->handle;
+	}
+
+	return NULL;
+}
+
+static acpi_status riscv_acpi_irq_get_parent(struct acpi_resource *ares, void *context)
+{
+	struct acpi_irq_dep_ctx *ctx = context;
+	struct acpi_resource_irq *irq;
+	struct acpi_resource_extended_irq *eirq;
+
+	switch (ares->type) {
+	case ACPI_RESOURCE_TYPE_IRQ:
+		irq = &ares->data.irq;
+		if (ctx->index >= irq->interrupt_count) {
+			ctx->index -= irq->interrupt_count;
+			return AE_OK;
+		}
+		ctx->handle = riscv_acpi_get_gsi_handle(irq->interrupts[ctx->index]);
+		return AE_CTRL_TERMINATE;
+	case ACPI_RESOURCE_TYPE_EXTENDED_IRQ:
+		eirq = &ares->data.extended_irq;
+		if (eirq->producer_consumer == ACPI_PRODUCER)
+			return AE_OK;
+
+		if (ctx->index >= eirq->interrupt_count) {
+			ctx->index -= eirq->interrupt_count;
+			return AE_OK;
+		}
+
+		/* Support GSIs only */
+		if (eirq->resource_source.string_length)
+			return AE_OK;
+
+		ctx->handle = riscv_acpi_get_gsi_handle(eirq->interrupts[ctx->index]);
+		return AE_CTRL_TERMINATE;
+	}
+
+	return AE_OK;
+}
+
+static int riscv_acpi_irq_get_dep(acpi_handle handle, unsigned int index, acpi_handle *gsi_handle)
+{
+	struct acpi_irq_dep_ctx ctx = {-EINVAL, index, NULL};
+
+	if (!gsi_handle)
+		return 0;
+
+	acpi_walk_resources(handle, METHOD_NAME__CRS, riscv_acpi_irq_get_parent, &ctx);
+	*gsi_handle = ctx.handle;
+	if (*gsi_handle)
+		return 1;
+
+	return 0;
+}
+
+static u32 riscv_acpi_add_prt_dep(acpi_handle handle)
+{
+	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_pci_routing_table *entry;
+	struct acpi_handle_list dep_devices;
+	acpi_handle gsi_handle;
+	acpi_handle link_handle;
+	acpi_status status;
+	u32 count = 0;
+
+	status = acpi_get_irq_routing_table(handle, &buffer);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_err(handle, "failed to get IRQ routing table\n");
+		kfree(buffer.pointer);
+		return 0;
+	}
+
+	entry = buffer.pointer;
+	while (entry && (entry->length > 0)) {
+		if (entry->source[0]) {
+			acpi_get_handle(handle, entry->source, &link_handle);
+			dep_devices.count = 1;
+			dep_devices.handles = kcalloc(1, sizeof(*dep_devices.handles), GFP_KERNEL);
+			if (!dep_devices.handles) {
+				acpi_handle_err(handle, "failed to allocate memory\n");
+				continue;
+			}
+
+			dep_devices.handles[0] = link_handle;
+			count += acpi_scan_add_dep(handle, &dep_devices);
+		} else {
+			gsi_handle = riscv_acpi_get_gsi_handle(entry->source_index);
+			dep_devices.count = 1;
+			dep_devices.handles = kcalloc(1, sizeof(*dep_devices.handles), GFP_KERNEL);
+			if (!dep_devices.handles) {
+				acpi_handle_err(handle, "failed to allocate memory\n");
+				continue;
+			}
+
+			dep_devices.handles[0] = gsi_handle;
+			count += acpi_scan_add_dep(handle, &dep_devices);
+		}
+
+		entry = (struct acpi_pci_routing_table *)
+			((unsigned long)entry + entry->length);
+	}
+
+	kfree(buffer.pointer);
+	return count;
+}
+
+static u32 riscv_acpi_add_irq_dep(acpi_handle handle)
+{
+	struct acpi_handle_list dep_devices;
+	acpi_handle gsi_handle;
+	u32 count = 0;
+	int i;
+
+	for (i = 0;
+	     riscv_acpi_irq_get_dep(handle, i, &gsi_handle);
+	     i++) {
+		dep_devices.count = 1;
+		dep_devices.handles = kcalloc(1, sizeof(*dep_devices.handles), GFP_KERNEL);
+		if (!dep_devices.handles) {
+			acpi_handle_err(handle, "failed to allocate memory\n");
+			continue;
+		}
+
+		dep_devices.handles[0] = gsi_handle;
+		count += acpi_scan_add_dep(handle, &dep_devices);
+	}
+
+	return count;
+}
+
+u32 arch_acpi_add_auto_dep(acpi_handle handle)
+{
+	if (acpi_has_method(handle, "_PRT"))
+		return riscv_acpi_add_prt_dep(handle);
+
+	return riscv_acpi_add_irq_dep(handle);
+}