ACPI: RISC-V: Add RPMI System MSI to GSI mapping

The RPMI System MSI device will provide GSIs to downstream devices
(such as GED) so add it to the RISC-V GSI to fwnode mapping.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
Link: https://lore.kernel.org/r/20250818040920.272664-20-apatel@ventanamicro.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>

Author: vlsunil

arch/riscv/include/asm/irq.h

@@ -32,6 +32,7 @@ enum riscv_irqchip_type {
 	ACPI_RISCV_IRQCHIP_IMSIC	= 0x01,
 	ACPI_RISCV_IRQCHIP_PLIC		= 0x02,
 	ACPI_RISCV_IRQCHIP_APLIC	= 0x03,
+	ACPI_RISCV_IRQCHIP_SMSI		= 0x04,
 };
 
 int riscv_acpi_get_gsi_info(struct fwnode_handle *fwnode, u32 *gsi_base,

drivers/acpi/riscv/irq.c

@@ -168,6 +168,33 @@ static int __init riscv_acpi_register_ext_intc(u32 gsi_base, u32 nr_irqs, u32 nr
 	return 0;
 }
 
+static acpi_status __init riscv_acpi_create_gsi_map_smsi(acpi_handle handle, u32 level,
+							 void *context, void **return_value)
+{
+	acpi_status status;
+	u64 gbase;
+
+	if (!acpi_has_method(handle, "_GSB")) {
+		acpi_handle_err(handle, "_GSB method not found\n");
+		return AE_ERROR;
+	}
+
+	status = acpi_evaluate_integer(handle, "_GSB", NULL, &gbase);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_err(handle, "failed to evaluate _GSB method\n");
+		return status;
+	}
+
+	riscv_acpi_register_ext_intc(gbase, 0, 0, 0, ACPI_RISCV_IRQCHIP_SMSI);
+	status = riscv_acpi_update_gsi_handle((u32)gbase, handle);
+	if (ACPI_FAILURE(status)) {
+		acpi_handle_err(handle, "failed to find the GSI mapping entry\n");
+		return status;
+	}
+
+	return AE_OK;
+}
+
 static acpi_status __init riscv_acpi_create_gsi_map(acpi_handle handle, u32 level,
 						    void *context, void **return_value)
 {
@@ -222,6 +249,9 @@ 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);
+
+	/* Unlike PLIC/APLIC, SYSMSI doesn't have MADT */
+	acpi_get_devices("RSCV0006", riscv_acpi_create_gsi_map_smsi, NULL, NULL);
 }
 
 static acpi_handle riscv_acpi_get_gsi_handle(u32 gsi)