ACPI: Add new IORT functions to support MSI domain handling

For ITS, MSI functionality consists on building domain stack and
during that process we need to reference to domain stack components
e.g. before we create new DOMAIN_BUS_PCI_MSI domain we need to specify
its DOMAIN_BUS_NEXUS parent domain. In order to manage that process
properly, maintain list which elements contain domain token
(unique for MSI domain stack) and ITS ID: iort_register_domain_token()
and iort_deregister_domain_token(). Then retrieve domain token
any time later with ITS ID being key off: iort_find_domain_token().
With domain token and domain type we are able to find corresponding
IRQ domain.

Since IORT is prepared to describe MSI domain on a per-device basis,
use existing IORT helpers and implement two calls:
1. iort_msi_map_rid() to map MSI RID for a device
2. iort_get_device_domain() to find domain token for a device

Signed-off-by: Tomasz Nowicki <tn@semihalf.com>
Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
index fcacaf7ed64d..0e32dac8fd03 100644
--- a/include/linux/acpi_iort.h
+++ b/include/linux/acpi_iort.h
@@ -20,11 +20,23 @@
 #define __ACPI_IORT_H__
 
 #include <linux/acpi.h>
+#include <linux/fwnode.h>
+#include <linux/irqdomain.h>
 
+int iort_register_domain_token(int trans_id, struct fwnode_handle *fw_node);
+void iort_deregister_domain_token(int trans_id);
+struct fwnode_handle *iort_find_domain_token(int trans_id);
 #ifdef CONFIG_ACPI_IORT
 void acpi_iort_init(void);
+u32 iort_msi_map_rid(struct device *dev, u32 req_id);
+struct irq_domain *iort_get_device_domain(struct device *dev, u32 req_id);
 #else
 static inline void acpi_iort_init(void) { }
+static inline u32 iort_msi_map_rid(struct device *dev, u32 req_id)
+{ return req_id; }
+static inline struct irq_domain *iort_get_device_domain(struct device *dev,
+							u32 req_id)
+{ return NULL; }
 #endif
 
 #endif /* __ACPI_IORT_H__ */