[PATCH v2 02/25] ACPI: irq: Add IRQ affinity reporting interface

[Marc Zyngier <maz@kernel.org>]

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   | 19 +++++++++++++++++++
 include/linux/acpi.h |  7 +++++++
 2 files changed, 26 insertions(+)

diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
index 76a856c32c4d0..d1595156c86a4 100644
--- a/drivers/acpi/irq.c
+++ b/drivers/acpi/irq.c
@@ -300,6 +300,25 @@ 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;
+	struct irq_fwspec fwspec;
+	unsigned long flags;
+
+	if (acpi_irq_parse_one(handle, index, &fwspec, &flags))
+		return NULL;
+
+	if (irq_populate_fwspec_info(&fwspec, &info))
+		return NULL;
+
+	if (!(info.flags & IRQ_FWSPEC_INFO_AFFINITY_VALID))
+		return NULL;
+
+	return info.affinity;
+}
+
 /**
  * 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
-- 
2.39.2