Plug the irq_populate_fwspec_info() helper into the ACPI layer
to offer an IRQ affinity reporting function. This is currently
only supported for the CONFIG_ACPI_GENERIC_GSI configurations,
but could later be extended to legacy architectures if necessary.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 drivers/acpi/irq.c   | 15 +++++++++++++++
 include/linux/acpi.h |  7 +++++++
 2 files changed, 22 insertions(+)

diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
index 76a856c32c4d0..22f93fe23ddce 100644
--- a/drivers/acpi/irq.c
+++ b/drivers/acpi/irq.c

@@ -300,6 +300,21 @@ int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res)
 }
 EXPORT_SYMBOL_GPL(acpi_irq_get);

+const struct cpumask *acpi_irq_get_affinity(acpi_handle handle,
+                                           unsigned int index)
+{
+       struct irq_fwspec_info info;
+       unsigned long flags;
+
+       if (!acpi_irq_parse_one(handle, index, &info.fwspec, &flags)) {
+               if (!irq_populate_fwspec_info(&info) &&
+                   info.flags & IRQ_FWSPEC_INFO_AFFINITY_VALID)
+                       return info.affinity;
+       }

+
+       return NULL;
+}
+
 /**
  * acpi_set_irq_model - Setup the GSI irqdomain information
  * @model: the value assigned to acpi_irq_model

diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 1c5bb1e887cd1..c506ae4bacc86 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h

@@ -1509,12 +1509,19 @@ static inline int acpi_parse_spcr(bool enable_earlycon, bool enable_console)

 #if IS_ENABLED(CONFIG_ACPI_GENERIC_GSI)
 int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res);
+const struct cpumask *acpi_irq_get_affinity(acpi_handle handle,
+                                           unsigned int index);
 #else
 static inline
 int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res)
 {
        return -EINVAL;
 }
+static inline const struct cpumask *acpi_irq_get_affinity(acpi_handle handle,
+                                                         unsigned int index)
+{
+       return NULL;
+}
 #endif

 #ifdef CONFIG_ACPI_LPIT
--