[PATCH 0/6] irqchip/al-fic: shared parent IRQ, FIC v2/v3 and affinity

[PATCH 0/6] irqchip/al-fic: shared parent IRQ, FIC v2/v3 and affinity

[Eliav Farber]

This series extends the Amazon Annapurna Labs Fabric Interrupt Controller
(FIC) driver to support newer hardware revisions and configurations found
on later Annapurna Labs SoCs, plus a couple of smaller fixes.

FIC v2 and later add two interrupt groups alongside the existing legacy
group - an "error" group and a "fatal" group - each described by its own
device tree node and matched by a distinct compatible string. On some
platforms several FIC instances also share a single parent GIC SPI, which
the driver did not previously support.

The series is organised as follows:

  1. Use the full node name in log messages and raise the successful-init
     message to pr_info, so each FIC instance is identifiable at boot.
  2. Request the parent interrupt as shared (IRQF_SHARED) instead of a
     chained handler, so multiple FIC instances can share one GIC SPI.
  3. Extend the binding with the amazon,al-fic-error and amazon,al-fic-fatal
     compatibles for the new groups.
  4. Add FIC v2 support: version detection, the error/fatal groups, and a
     mask_cache workaround for a v2 erratum where the error and fatal mask
     registers always read back as 0.
  5. Add FIC v3 support. v3 shares v2's group layout but fixes the mask
     read-back erratum, so the v2 workaround is deliberately not applied.
  6. Add an irq_set_affinity callback so drivers that call
     irq_set_affinity() (which fails with -EINVAL when the irqchip has no
     such callback) can probe when routed through a FIC instance.

Eliav Farber (6):
  irqchip/al-fic: use full node name and raise init log level
  irqchip/al-fic: switch to shared parent interrupt
  dt-bindings: interrupt-controller: amazon,al-fic: add error/fatal
    groups
  irqchip/al-fic: add support for FIC v2
  irqchip/al-fic: add support for FIC v3
  irqchip/al-fic: add irq_set_affinity callback

 .../interrupt-controller/amazon,al-fic.yaml   |   5 +-
 drivers/irqchip/irq-al-fic.c                  | 176 +++++++++++++++---
 2 files changed, 150 insertions(+), 31 deletions(-)


base-commit: 6828157ab3e96cd1c957b78d995c5e508a2eb2c2
-- 
2.47.3

[PATCH 1/6] irqchip/al-fic: use full node name and raise init log level

[Eliav Farber]

Use node->full_name instead of node->name in the driver's log messages
so that they identify the specific FIC instance, e.g.:

  interrupt-controller@fd803000 initialized successfully in Legacy mode (parent-irq=3)

Raise the successful-initialization message from pr_debug to pr_info, as
this single boot-time printout is useful when dynamic debug is not
enabled at this stage of boot. While here, fix a small typo in the
al_fic_wire_init() comment.

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 drivers/irqchip/irq-al-fic.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/irqchip/irq-al-fic.c b/drivers/irqchip/irq-al-fic.c
index d10ac9b63c99..efa7f2b62d00 100644
--- a/drivers/irqchip/irq-al-fic.c
+++ b/drivers/irqchip/irq-al-fic.c
@@ -180,7 +180,7 @@ static int al_fic_register(struct device_node *node,
  * @name: name of the fic
  * @parent_irq: interrupt of parent
  *
- * This API will configure the fic hardware to to work in wire mode.
+ * This API will configure the fic hardware to work in wire mode.
  * In wire mode, fic hardware is generating a wire ("wired") interrupt.
  * Interrupt can be generated based on positive edge or level - configuration is
  * to be determined based on connected hardware to this fic.
@@ -216,8 +216,8 @@ static struct al_fic *al_fic_wire_init(struct device_node *node,
 		goto err_free;
 	}
 
-	pr_debug("%s initialized successfully in Legacy mode (parent-irq=%u)\n",
-		 fic->name, parent_irq);
+	pr_info("%s initialized successfully in Legacy mode (parent-irq=%u)\n",
+		fic->name, parent_irq);
 
 	return fic;
 
@@ -236,30 +236,30 @@ static int __init al_fic_init_dt(struct device_node *node,
 
 	if (!parent) {
 		pr_err("%s: unsupported - device require a parent\n",
-		       node->name);
+		       node->full_name);
 		return -EINVAL;
 	}
 
 	base = of_iomap(node, 0);
 	if (!base) {
-		pr_err("%s: fail to map memory\n", node->name);
+		pr_err("%s: fail to map memory\n", node->full_name);
 		return -ENOMEM;
 	}
 
 	parent_irq = irq_of_parse_and_map(node, 0);
 	if (!parent_irq) {
-		pr_err("%s: fail to map irq\n", node->name);
+		pr_err("%s: fail to map irq\n", node->full_name);
 		ret = -EINVAL;
 		goto err_unmap;
 	}
 
 	fic = al_fic_wire_init(node,
 			       base,
-			       node->name,
+			       node->full_name,
 			       parent_irq);
 	if (IS_ERR(fic)) {
 		pr_err("%s: fail to initialize irqchip (%lu)\n",
-		       node->name,
+		       node->full_name,
 		       PTR_ERR(fic));
 		ret = PTR_ERR(fic);
 		goto err_irq_dispose;
-- 
2.47.3

[PATCH 2/6] irqchip/al-fic: switch to shared parent interrupt

[Eliav Farber]

Until now the driver requested its parent interrupt using the chained
IRQ API (irq_set_chained_handler_and_data()), which only works when each
parent interrupt is wired to a single FIC instance.

On some platforms several FIC instances share the same parent GIC SPI.
To support that, request the parent interrupt as a shared interrupt
(IRQF_SHARED) instead of installing a chained handler. The handler now
has the standard irqreturn_t prototype and reports whether it handled any
child interrupt, so the shared-IRQ core can dispatch to the correct
instance.

generic_handle_domain_irq() is retained for dispatch; its return value is
used to determine whether a pending child was actually handled so the
handler can return IRQ_HANDLED/IRQ_NONE correctly.

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 drivers/irqchip/irq-al-fic.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/irqchip/irq-al-fic.c b/drivers/irqchip/irq-al-fic.c
index efa7f2b62d00..9cf3eedac97f 100644
--- a/drivers/irqchip/irq-al-fic.c
+++ b/drivers/irqchip/irq-al-fic.c
@@ -4,9 +4,9 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/irqchip.h>
-#include <linux/irqchip/chained_irq.h>
 #include <linux/irqdomain.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -95,24 +95,24 @@ static int al_fic_irq_set_type(struct irq_data *data, unsigned int flow_type)
 	return 0;
 }
 
-static void al_fic_irq_handler(struct irq_desc *desc)
+static irqreturn_t al_fic_irq_handler(int irq, void *data)
 {
-	struct al_fic *fic = irq_desc_get_handler_data(desc);
+	struct al_fic *fic = data;
 	struct irq_domain *domain = fic->domain;
-	struct irq_chip *irqchip = irq_desc_get_chip(desc);
 	struct irq_chip_generic *gc = irq_get_domain_generic_chip(domain, 0);
+	irqreturn_t ret = IRQ_NONE;
 	unsigned long pending;
 	u32 hwirq;
 
-	chained_irq_enter(irqchip, desc);
-
 	pending = readl_relaxed(fic->base + AL_FIC_CAUSE);
 	pending &= ~gc->mask_cache;
 
-	for_each_set_bit(hwirq, &pending, NR_FIC_IRQS)
-		generic_handle_domain_irq(domain, hwirq);
+	for_each_set_bit(hwirq, &pending, NR_FIC_IRQS) {
+		if (!generic_handle_domain_irq(domain, hwirq))
+			ret = IRQ_HANDLED;
+	}
 
-	chained_irq_exit(irqchip, desc);
+	return ret;
 }
 
 static int al_fic_irq_retrigger(struct irq_data *data)
@@ -162,11 +162,17 @@ static int al_fic_register(struct device_node *node,
 	gc->chip_types->chip.flags = IRQCHIP_SKIP_SET_WAKE;
 	gc->private = fic;
 
-	irq_set_chained_handler_and_data(fic->parent_irq,
-					 al_fic_irq_handler,
-					 fic);
+	ret = request_irq(fic->parent_irq, al_fic_irq_handler,
+			  IRQF_NO_THREAD | IRQF_SHARED, fic->name, fic);
+	if (ret) {
+		pr_err("fail to request irq (%d)\n", ret);
+		goto err_free_generic_chip;
+	}
+
 	return 0;
 
+err_free_generic_chip:
+	irq_free_generic_chip(gc);
 err_domain_remove:
 	irq_domain_remove(fic->domain);
 
-- 
2.47.3

[PATCH 3/6] dt-bindings: interrupt-controller: amazon,al-fic: add error/fatal groups

[Eliav Farber]

FIC v2 and later expose two additional interrupt groups alongside the
legacy group - an error group and a fatal group - each described by its
own node and matched by a distinct compatible string. Turn the single
compatible into an enum covering all three:

  amazon,al-fic         - legacy group
  amazon,al-fic-error   - error group
  amazon,al-fic-fatal   - fatal group

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 .../bindings/interrupt-controller/amazon,al-fic.yaml         | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/interrupt-controller/amazon,al-fic.yaml b/Documentation/devicetree/bindings/interrupt-controller/amazon,al-fic.yaml
index 26bc05dee0bc..f43039901bd3 100644
--- a/Documentation/devicetree/bindings/interrupt-controller/amazon,al-fic.yaml
+++ b/Documentation/devicetree/bindings/interrupt-controller/amazon,al-fic.yaml
@@ -11,7 +11,10 @@ maintainers:
 
 properties:
   compatible:
-    const: amazon,al-fic
+    enum:
+      - amazon,al-fic
+      - amazon,al-fic-error
+      - amazon,al-fic-fatal
 
   reg:
     maxItems: 1
-- 
2.47.3

Re: [PATCH 3/6] dt-bindings: interrupt-controller: amazon,al-fic: add error/fatal groups

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 1843 bytes --]

On Thu, Sep 24, 2026 at 06:23:08AM +0000, Eliav Farber wrote:
> FIC v2 and later expose two additional interrupt groups alongside the
> legacy group - an error group and a fatal group - each described by its
> own node and matched by a distinct compatible string. Turn the single
> compatible into an enum covering all three:

Without any explanation relating to hardware, I find this very hard to
understand. Nodes and compatible strings are devicetree concepts, that
portion of the commit message should explain hardware detail.

What this sounds like from your commit message is that you have a new
revision of this block, and instead of adding an al-fic-v2 compatible,
you're using two new compatibles to describe the new features and using
the old compatible to describe the common featureset. Without a dts, I
cannot say for sure.

pw-bot: changes-requested

> 
>   amazon,al-fic         - legacy group
>   amazon,al-fic-error   - error group
>   amazon,al-fic-fatal   - fatal group
> 
> Signed-off-by: Eliav Farber <farbere@amazon.com>
> ---
>  .../bindings/interrupt-controller/amazon,al-fic.yaml         | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/interrupt-controller/amazon,al-fic.yaml b/Documentation/devicetree/bindings/interrupt-controller/amazon,al-fic.yaml
> index 26bc05dee0bc..f43039901bd3 100644
> --- a/Documentation/devicetree/bindings/interrupt-controller/amazon,al-fic.yaml
> +++ b/Documentation/devicetree/bindings/interrupt-controller/amazon,al-fic.yaml
> @@ -11,7 +11,10 @@ maintainers:
>  
>  properties:
>    compatible:
> -    const: amazon,al-fic
> +    enum:
> +      - amazon,al-fic
> +      - amazon,al-fic-error
> +      - amazon,al-fic-fatal
>  
>    reg:
>      maxItems: 1
> -- 
> 2.47.3
> 

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

[PATCH 4/6] irqchip/al-fic: add support for FIC v2

[Eliav Farber]

FIC v2 hardware adds two additional interrupt groups on top of the
legacy group: an "error" group and a "fatal" group, each with its own
mask register (AL_FIC_ERROR_MASK, AL_FIC_FATAL_MASK). A single FIC
instance exposes one of these groups, selected by the compatible string.

Detect the hardware version from the CONTROL register version id field
(bits 28-29) and, on v2, mask out the error and fatal groups during
initialization.

The driver now distinguishes the three groups via enum al_fic_id, wired
up through three IRQCHIP_DECLARE entries:

  amazon,al-fic         - legacy group (existing, unchanged behaviour)
  amazon,al-fic-error   - error group  (v2+)
  amazon,al-fic-fatal   - fatal group  (v2+)

Requesting an error/fatal group on a v1 device is rejected.

On v2 the error and fatal mask registers always read back as 0,
regardless of their actual contents, so IRQ_GC_INIT_MASK_CACHE seeds
mask_cache with 0 and makes every source appear unmasked on the next
access. Since al_fic_wire_init() has already masked all sources, override
mask_cache to match for these two groups and let the driver maintain it.
The legacy mask register is not affected, so the legacy group keeps the
register-seeded mask_cache.

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 drivers/irqchip/irq-al-fic.c | 101 ++++++++++++++++++++++++++++++-----
 1 file changed, 89 insertions(+), 12 deletions(-)

diff --git a/drivers/irqchip/irq-al-fic.c b/drivers/irqchip/irq-al-fic.c
index 9cf3eedac97f..90a64350be63 100644
--- a/drivers/irqchip/irq-al-fic.c
+++ b/drivers/irqchip/irq-al-fic.c
@@ -16,11 +16,14 @@
 /* FIC Registers */
 #define AL_FIC_CAUSE		0x00
 #define AL_FIC_SET_CAUSE	0x08
-#define AL_FIC_MASK		0x10
+#define AL_FIC_LEGACY_MASK	0x10
 #define AL_FIC_CONTROL		0x28
+#define AL_FIC_ERROR_MASK	0x2c
+#define AL_FIC_FATAL_MASK	0x34
 
 #define CONTROL_TRIGGER_RISING	BIT(3)
 #define CONTROL_MASK_MSI_X	BIT(5)
+#define CONTROL_VERSION_ID	GENMASK(29, 28)
 
 #define NR_FIC_IRQS 32
 
@@ -33,12 +36,32 @@ enum al_fic_state {
 	AL_FIC_CONFIGURED_RISING_EDGE,
 };
 
+enum al_fic_version {
+	AL_FIC_VERSION_V1,
+	AL_FIC_VERSION_V2,
+};
+
+enum al_fic_id {
+	AL_FIC_ID_LEGACY,
+	AL_FIC_ID_ERROR,
+	AL_FIC_ID_FATAL,
+	AL_FIC_ID_MAX,		/* keep last */
+};
+
+/* Mask register offset for each interrupt group */
+static const unsigned int al_fic_mask_offset[AL_FIC_ID_MAX] = {
+	[AL_FIC_ID_LEGACY] = AL_FIC_LEGACY_MASK,
+	[AL_FIC_ID_ERROR]  = AL_FIC_ERROR_MASK,
+	[AL_FIC_ID_FATAL]  = AL_FIC_FATAL_MASK,
+};
+
 struct al_fic {
 	void __iomem *base;
 	struct irq_domain *domain;
 	const char *name;
 	unsigned int parent_irq;
 	enum al_fic_state state;
+	enum al_fic_version version;
 };
 
 static void al_fic_set_trigger(struct al_fic *fic,
@@ -126,7 +149,8 @@ static int al_fic_irq_retrigger(struct irq_data *data)
 }
 
 static int al_fic_register(struct device_node *node,
-			   struct al_fic *fic)
+			   struct al_fic *fic,
+			   enum al_fic_id fic_id)
 {
 	struct irq_chip_generic *gc;
 	int ret;
@@ -152,7 +176,7 @@ static int al_fic_register(struct device_node *node,
 
 	gc = irq_get_domain_generic_chip(fic->domain, 0);
 	gc->reg_base = fic->base;
-	gc->chip_types->regs.mask = AL_FIC_MASK;
+	gc->chip_types->regs.mask = al_fic_mask_offset[fic_id];
 	gc->chip_types->regs.ack = AL_FIC_CAUSE;
 	gc->chip_types->chip.irq_mask = irq_gc_mask_set_bit;
 	gc->chip_types->chip.irq_unmask = irq_gc_mask_clr_bit;
@@ -162,6 +186,20 @@ static int al_fic_register(struct device_node *node,
 	gc->chip_types->chip.flags = IRQCHIP_SKIP_SET_WAKE;
 	gc->private = fic;
 
+	/*
+	 * On FIC v2 the error and fatal mask registers always read back as 0,
+	 * regardless of their actual contents, so IRQ_GC_INIT_MASK_CACHE seeds
+	 * mask_cache with 0 and makes every source appear unmasked on the next
+	 * access. al_fic_wire_init() has already masked all sources, so override
+	 * mask_cache to match and let the driver maintain it from here.
+	 *
+	 * The legacy mask register is not affected, and the erratum is fixed
+	 * from v3 onwards, so those paths keep the register-seeded mask_cache.
+	 */
+	if (fic->version == AL_FIC_VERSION_V2 &&
+	    (fic_id == AL_FIC_ID_ERROR || fic_id == AL_FIC_ID_FATAL))
+		gc->mask_cache = 0xFFFFFFFF;
+
 	ret = request_irq(fic->parent_irq, al_fic_irq_handler,
 			  IRQF_NO_THREAD | IRQF_SHARED, fic->name, fic);
 	if (ret) {
@@ -194,11 +232,13 @@ static int al_fic_register(struct device_node *node,
 static struct al_fic *al_fic_wire_init(struct device_node *node,
 				       void __iomem *base,
 				       const char *name,
-				       unsigned int parent_irq)
+				       unsigned int parent_irq,
+				       enum al_fic_id fic_id)
 {
 	struct al_fic *fic;
+	u32 version_id;
+	u32 control;
 	int ret;
-	u32 control = CONTROL_MASK_MSI_X;
 
 	fic = kzalloc_obj(*fic);
 	if (!fic)
@@ -208,22 +248,37 @@ static struct al_fic *al_fic_wire_init(struct device_node *node,
 	fic->parent_irq = parent_irq;
 	fic->name = name;
 
+	control = readl_relaxed(fic->base + AL_FIC_CONTROL);
+	version_id = FIELD_GET(CONTROL_VERSION_ID, control);
+	fic->version = version_id;
+	if (version_id == AL_FIC_VERSION_V1 && fic_id != AL_FIC_ID_LEGACY) {
+		pr_err("%s unexpected fic id (%d)\n", fic->name, fic_id);
+		ret = -EINVAL;
+		goto err_free;
+	}
+
 	/* mask out all interrupts */
-	writel_relaxed(0xFFFFFFFF, fic->base + AL_FIC_MASK);
+	writel_relaxed(0xFFFFFFFF, fic->base + AL_FIC_LEGACY_MASK);
+	if (version_id > AL_FIC_VERSION_V1) {
+		writel_relaxed(0xFFFFFFFF, fic->base + AL_FIC_ERROR_MASK);
+		writel_relaxed(0xFFFFFFFF, fic->base + AL_FIC_FATAL_MASK);
+	}
 
 	/* clear any pending interrupt */
 	writel_relaxed(0, fic->base + AL_FIC_CAUSE);
 
+	/* make sure the controller works in non msi_x mode */
+	control |= CONTROL_MASK_MSI_X;
 	writel_relaxed(control, fic->base + AL_FIC_CONTROL);
 
-	ret = al_fic_register(node, fic);
+	ret = al_fic_register(node, fic, fic_id);
 	if (ret) {
 		pr_err("fail to register irqchip\n");
 		goto err_free;
 	}
 
-	pr_info("%s initialized successfully in Legacy mode (parent-irq=%u)\n",
-		fic->name, parent_irq);
+	pr_info("%s initialized successfully (fic_id=%d parent-irq=%u)\n",
+		fic->name, fic_id, parent_irq);
 
 	return fic;
 
@@ -233,7 +288,8 @@ static struct al_fic *al_fic_wire_init(struct device_node *node,
 }
 
 static int __init al_fic_init_dt(struct device_node *node,
-				 struct device_node *parent)
+				 struct device_node *parent,
+				 enum al_fic_id fic_id)
 {
 	int ret;
 	void __iomem *base;
@@ -262,7 +318,8 @@ static int __init al_fic_init_dt(struct device_node *node,
 	fic = al_fic_wire_init(node,
 			       base,
 			       node->full_name,
-			       parent_irq);
+			       parent_irq,
+			       fic_id);
 	if (IS_ERR(fic)) {
 		pr_err("%s: fail to initialize irqchip (%lu)\n",
 		       node->full_name,
@@ -281,4 +338,24 @@ static int __init al_fic_init_dt(struct device_node *node,
 	return ret;
 }
 
-IRQCHIP_DECLARE(al_fic, "amazon,al-fic", al_fic_init_dt);
+static int __init al_fic_init_dt_legacy(struct device_node *node,
+					struct device_node *parent)
+{
+	return al_fic_init_dt(node, parent, AL_FIC_ID_LEGACY);
+}
+
+static int __init al_fic_init_dt_error(struct device_node *node,
+				       struct device_node *parent)
+{
+	return al_fic_init_dt(node, parent, AL_FIC_ID_ERROR);
+}
+
+static int __init al_fic_init_dt_fatal(struct device_node *node,
+				       struct device_node *parent)
+{
+	return al_fic_init_dt(node, parent, AL_FIC_ID_FATAL);
+}
+
+IRQCHIP_DECLARE(al_fic_legacy, "amazon,al-fic", al_fic_init_dt_legacy);
+IRQCHIP_DECLARE(al_fic_error, "amazon,al-fic-error", al_fic_init_dt_error);
+IRQCHIP_DECLARE(al_fic_fatal, "amazon,al-fic-fatal", al_fic_init_dt_fatal);
-- 
2.47.3

[PATCH 5/6] irqchip/al-fic: add support for FIC v3

[Eliav Farber]

FIC v3 reports version id 2 in the control register version field. It
exposes the same legacy/error/fatal groups as v2, so add the version to
enum al_fic_version; the existing "version_id > V1" handling masks the
error and fatal groups at init as for v2.

Unlike v2, the v3 error and fatal mask registers read back correctly, so
v3 does not need the v2 mask_cache workaround: the workaround is gated on
AL_FIC_VERSION_V2 and v3 keeps the register-seeded mask_cache.

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 drivers/irqchip/irq-al-fic.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/irqchip/irq-al-fic.c b/drivers/irqchip/irq-al-fic.c
index 90a64350be63..d9f5d8d8a4ba 100644
--- a/drivers/irqchip/irq-al-fic.c
+++ b/drivers/irqchip/irq-al-fic.c
@@ -39,6 +39,7 @@ enum al_fic_state {
 enum al_fic_version {
 	AL_FIC_VERSION_V1,
 	AL_FIC_VERSION_V2,
+	AL_FIC_VERSION_V3,
 };
 
 enum al_fic_id {
-- 
2.47.3

[PATCH 6/6] irqchip/al-fic: add irq_set_affinity callback

[Eliav Farber]

The FIC aggregates up to 32 interrupt sources into a single parent GIC
SPI and has no per-child affinity control; affinity is determined by the
parent GIC SPI routing.

irq_set_affinity() fails with -EINVAL when the target irqchip has no
irq_set_affinity callback, which prevents drivers that call it from
probing when their interrupt is routed through a FIC instance. Add an
irq_set_affinity callback that returns IRQ_SET_MASK_OK_DONE
unconditionally.

Affinity requests cannot be forwarded to the parent GIC SPI, because it
may be shared by several FIC instances and changing its affinity for one
child would silently move all the others. A dev_warn_once() is emitted
when the requested affinity differs from the parent's current affinity,
giving visibility without failing the caller.

Signed-off-by: Eliav Farber <farbere@amazon.com>
---
 drivers/irqchip/irq-al-fic.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/irqchip/irq-al-fic.c b/drivers/irqchip/irq-al-fic.c
index d9f5d8d8a4ba..8ad753ef121a 100644
--- a/drivers/irqchip/irq-al-fic.c
+++ b/drivers/irqchip/irq-al-fic.c
@@ -149,6 +149,37 @@ static int al_fic_irq_retrigger(struct irq_data *data)
 	return 1;
 }
 
+/*
+ * The FIC aggregates up to 32 child interrupts into a single parent GIC SPI.
+ * It has no hardware affinity control - all children inherit the parent's
+ * CPU routing. Affinity requests cannot be forwarded to the parent, because
+ * a parent GIC SPI may be shared by multiple FIC instances and changing its
+ * affinity for one child would silently move all the others.
+ *
+ * Return IRQ_SET_MASK_OK_DONE unconditionally so that callers using
+ * irq_set_affinity() do not fail with -EINVAL for lack of this callback.
+ */
+static int al_fic_irq_set_affinity(struct irq_data *data,
+				   const struct cpumask *mask, bool force)
+{
+	struct irq_chip_generic *gc = irq_data_get_irq_chip_data(data);
+	const struct cpumask *parent_affinity;
+	struct al_fic *fic = gc->private;
+	struct irq_data *parent_data;
+
+	parent_data = irq_get_irq_data(fic->parent_irq);
+	if (!parent_data)
+		return -EINVAL;
+
+	parent_affinity = irq_data_get_affinity_mask(parent_data);
+	if (!cpumask_equal(mask, parent_affinity))
+		dev_warn_once(gc->domain->dev,
+			      "affinity change requested but FIC is fixed to parent IRQ %u CPU routing\n",
+			      fic->parent_irq);
+
+	return IRQ_SET_MASK_OK_DONE;
+}
+
 static int al_fic_register(struct device_node *node,
 			   struct al_fic *fic,
 			   enum al_fic_id fic_id)
@@ -184,6 +215,7 @@ static int al_fic_register(struct device_node *node,
 	gc->chip_types->chip.irq_ack = irq_gc_ack_clr_bit;
 	gc->chip_types->chip.irq_set_type = al_fic_irq_set_type;
 	gc->chip_types->chip.irq_retrigger = al_fic_irq_retrigger;
+	gc->chip_types->chip.irq_set_affinity = al_fic_irq_set_affinity;
 	gc->chip_types->chip.flags = IRQCHIP_SKIP_SET_WAKE;
 	gc->private = fic;
 
-- 
2.47.3