irqchip/al-fic: shared parent IRQ, error/fatal outputs and affinity

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

The block the driver calls a FIC is the generic Annapurna Labs interrupt controller, built from groups of up to 32 triggers each. A device tree node describes one group, not a whole controller, and the groups of one controller share that controller's output line toward the parent GIC SPI. Later revisions add two interrupt outputs on top of the original "info" output - an "error" output and a "fatal" output - each with its own mask register. Which output a group drives is fixed when the SoC is wired.

The series is organised as follows:

1. Fix an argument alignment and a repeated word flagged by checkpatch. No functional change.
2. Use %pOF in log messages and raise the successful-init message to pr_info, so each FIC instance is identifiable at boot.
3. Keep the device_node in struct al_fic instead of a cached name string that aliased node storage.
4. Request the parent interrupt as shared (IRQF_SHARED) instead of a chained handler, so the several nodes of one controller can share one GIC SPI.
5. Extend the binding with an optional amazon,al-fic-mask property (info, error or fatal; default info) selecting which output a group drives.
6. Add error/fatal output support and FIC v2: version detection from the control register, the two extra mask registers, and a mask_cache workaround for a v2 erratum where the error and fatal mask registers always read back as 0.
7. 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.
8. 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.

Patches 4 and 8 are co-developed with Talel Shenhar, the al-fic driver maintainer, and carry his Signed-off-by.

Changes in v3 - all from Radu Rendec's review of the v2 series. Patches 1, 2, 5 and 7 are unchanged and carry the tags he and Conor Dooley gave them; patches 3, 4 and 6 changed; patch 8 is unchanged and its open question is still being discussed on the v2 thread.
- patch 3: use of_node_full_name() instead of reaching into node->full_name. The commit message is rewritten to say plainly that this patch does not fix a lifetime bug - of_irq_init() pins the node for the life of the system on a successful init, so node->name was never at risk of dangling. The value is making the dependency explicit.
- patch 4: al_fic_irq_handler() no longer derives its return value from generic_handle_domain_irq(), which only reports whether the hwirq mapping succeeded. It now returns IRQ_HANDLED when the masked CAUSE snapshot is non-zero, which is the correct signal for a shared interrupt.
- patch 4: set IRQ_DOMAIN_FLAG_DESTROY_GC on the domain and let irq_domain_remove() free the generic chips, instead of calling irq_domain_remove_generic_chips() by hand. Both error paths collapse into one label. The invalid-free fix from v2 is unaffected; only the teardown mechanism changed.
- patch 4: use of_node_full_name() in the request_irq() call.
- patch 6: initialise gc_flags to IRQ_GC_INIT_MASK_CACHE at its declaration and only clear it on the v2 error/fatal path, dropping the else branch.
- patch 6: use ~0U instead of 0xFFFFFFFF for the mask_cache seed and the three mask register writes.
- patch 6: the commit message now explains the control register read-modify-write. Every writable bit in that register resets to 0, so preserving the other bits is equivalent to the previous plain write at probe time; it is not a behaviour fix.

v2: https://lore.kernel.org/all/[email protected]/
v1: https://lore.kernel.org/all/[email protected]/

Eliav Farber (8):
irqchip/al-fic: fix argument alignment and a repeated word irqchip/al-fic: use %pOF and raise init log level irqchip/al-fic: keep the device_node instead of a cached name string irqchip/al-fic: switch to shared parent interrupt
dt-bindings: interrupt-controller: amazon,al-fic: add mask selection irqchip/al-fic: support error and fatal outputs and FIC v2 irqchip/al-fic: add support for FIC v3
irqchip/al-fic: add irq_set_affinity callback

 .../interrupt-controller/amazon,al-fic.yaml   |  16 +-
 drivers/irqchip/irq-al-fic.c                  | 228 +++++++++++++++---
 2 files changed, 203 insertions(+), 41 deletions(-)

base-commit: e767a4ea70a3992c37ed604157d32f0dfbf9b1e3

2.47.3

The continuation lines of the irq_domain_create_linear() call sit three columns short of the open parenthesis. They were aligned for irq_domain_add_linear(); commit affdc0d1bdfa ("irqchip: Switch to irq_domain_create_*()") renamed the function to one three characters longer and left the indentation as it was. checkpatch --strict reports "Alignment should match open parenthesis".

al_fic_wire_init()'s kernel-doc reads "the fic hardware to to work in wire mode". checkpatch reports "Possible repeated word: 'to'".

No functional change.

---
v3: no change. Added Reviewed-by: Radu Rendec.

v2: new patch. checkpatch --strict cleanups (argument alignment and a
repeated word) split out ahead of the functional changes; the touched lines also appear as context in patches 3 and 6.

 drivers/irqchip/irq-al-fic.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

index d10ac9b63c99..35581332b40e 100644
@@ -132,9 +132,9 @@ static int al_fic_register(struct device_node *node,
 	int ret;
 
 	fic->domain = irq_domain_create_linear(of_fwnode_handle(node),
-					    NR_FIC_IRQS,
-					    &irq_generic_chip_ops,
-					    fic);
+					       NR_FIC_IRQS,
+					       &irq_generic_chip_ops,
+					       fic);
 	if (!fic->domain) {
 		pr_err("fail to add irq domain\n");
 		return -ENOMEM;

@@ -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.

2.47.3

Use %pOF in the driver's log messages, so that both the success and the error paths identify the specific FIC instance by its full devicetree path rather than by its bare node name, e.g.:

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

A single controller is described by several FIC nodes that share the same bare node name (e.g. "interrupt-controller"), so the bare name cannot tell one instance from another. The full path includes the unit address and keeps the instances distinguishable.

While converting the parent-missing message, fix a grammar typo in it ("device require a parent" -> "device requires a parent").

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.

---
v3: no change. Added Reviewed-by: Radu Rendec.

v2: reworded to explain why %pOF matters (several nodes of one controller
share the same bare node name, so only the full path with the unit address distinguishes them). Also switched from full_name string to %pOF. No functional change from v1's "use full node name" patch beyond the log level and the grammar fix.

 drivers/irqchip/irq-al-fic.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

index 35581332b40e..760bd08dcff4 100644
@@ -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("%pOF initialized successfully in Legacy mode (parent-irq=%u)\n",
+		node, parent_irq);
 
 	return fic;
 

@@ -235,20 +235,19 @@ static int __init al_fic_init_dt(struct device_node *node,
 	struct al_fic *fic;
 
 	if (!parent) {
-		pr_err("%s: unsupported - device require a parent\n",
-		       node->name);
+		pr_err("%pOF: unsupported - device requires a parent\n", node);
 		return -EINVAL;
 	}
 
 	base = of_iomap(node, 0);
 	if (!base) {
-		pr_err("%s: fail to map memory\n", node->name);
+		pr_err("%pOF: fail to map memory\n", node);
 		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("%pOF: fail to map irq\n", node);
 		ret = -EINVAL;
 		goto err_unmap;
 	}

@@ -258,9 +257,8 @@ static int __init al_fic_init_dt(struct device_node *node,
 			       node->name,
 			       parent_irq);
 	if (IS_ERR(fic)) {
-		pr_err("%s: fail to initialize irqchip (%lu)\n",
-		       node->name,
-		       PTR_ERR(fic));
+		pr_err("%pOF: fail to initialize irqchip (%lu)\n",
+		       node, PTR_ERR(fic));
 		ret = PTR_ERR(fic);
 		goto err_irq_dispose;
 	}

2.47.3

struct al_fic cached a "const char *name" that al_fic_wire_init() received as a separate argument and set from node->name. That string aliased storage inside the device_node rather than being owned by the driver, but nothing in the struct expressed that dependency - al_fic just held a bare pointer with no indication of what it pointed into or why it stayed valid.

This is not fixing a lifetime bug - of_irq_init() takes a reference on the node before calling the driver's init callback and never drops it on a successful init, so the node is pinned for the life of the system either way, and node->name was never actually at risk of dangling.

Keeping the device_node in the struct instead of the bare name is about making the dependency explicit rather than closing a real one: it holds the object the name is derived from, and lets each site derive the name on demand instead of carrying a pointer whose validity nothing in the struct asserts.

The irqchip callback that has no device_node in scope now prints the instance with %pOF, which formats the node on demand, and the name argument threaded through al_fic_wire_init() goes away.

irq_alloc_domain_generic_chips() keeps the pointer it is given, so it now uses of_node_full_name(). This changes the generic chip name from the bare node name (e.g. "interrupt-controller") to the full node name including its unit address (e.g. "interrupt-controller@fd8a8500"), which keeps instances that share a bare name distinguishable.

---
v3:
- Use of_node_full_name() instead of reaching into node->full_name directly, as Radu Rendec suggested.
- Rewrite the commit message to say plainly that this patch does not fix a lifetime bug. of_irq_init() takes a reference on the node before calling the driver's init callback and does not drop it on a successful init, so the node, and the storage node->name points into, is pinned for the life of the system either way. The value of keeping the device_node is making that dependency explicit, not closing a real one.

v2: new patch. Keep the device_node in struct al_fic instead of a cached
name string that aliased node storage. Introduced here so the struct holds the node before the next patch requests the parent interrupt by node->full_name, keeping every commit buildable on its own.

 drivers/irqchip/irq-al-fic.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

index 760bd08dcff4..ee06d0123b7a 100644
@@ -36,7 +36,7 @@ enum al_fic_state {
 struct al_fic {
 	void __iomem *base;
 	struct irq_domain *domain;
-	const char *name;
+	struct device_node *node;
 	unsigned int parent_irq;
 	enum al_fic_state state;
 };

@@ -89,7 +89,7 @@ static int al_fic_irq_set_type(struct irq_data *data, unsigned int flow_type)
 	if (fic->state == AL_FIC_UNCONFIGURED) {
 		al_fic_set_trigger(fic, gc, new_state);
 	} else if (fic->state != new_state) {
-		pr_debug("fic %s state already configured to %d\n", fic->name, fic->state);
+		pr_debug("fic %pOF state already configured to %d\n", fic->node, fic->state);
 		return -EINVAL;
 	}
 	return 0;

@@ -142,7 +142,7 @@ static int al_fic_register(struct device_node *node,
 
 	ret = irq_alloc_domain_generic_chips(fic->domain,
 					     NR_FIC_IRQS,
-					     1, fic->name,
+					     1, of_node_full_name(fic->node),
 					     handle_level_irq,
 					     0, 0, IRQ_GC_INIT_MASK_CACHE);
 	if (ret) {

@@ -175,9 +175,8 @@ static int al_fic_register(struct device_node *node,
 
 /*
  * al_fic_wire_init() - initialize and configure fic in wire mode
- * @of_node: optional pointer to interrupt controller's device tree node.
+ * @node: pointer to the interrupt controller's device tree node
  * @base: mmio to fic register
- * @name: name of the fic
  * @parent_irq: interrupt of parent
  *
  * This API will configure the fic hardware to work in wire mode.

@@ -187,7 +186,6 @@ 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)
 {
 	struct al_fic *fic;

@@ -200,7 +198,7 @@ static struct al_fic *al_fic_wire_init(struct device_node *node,
 
 	fic->base = base;
 	fic->parent_irq = parent_irq;
-	fic->name = name;
+	fic->node = node;
 
 	/* mask out all interrupts */
 	writel_relaxed(0xFFFFFFFF, fic->base + AL_FIC_MASK);

@@ -254,7 +252,6 @@ static int __init al_fic_init_dt(struct device_node *node,
 
 	fic = al_fic_wire_init(node,
 			       base,
-			       node->name,
 			       parent_irq);
 	if (IS_ERR(fic)) {
 		pr_err("%pOF: fail to initialize irqchip (%lu)\n",

2.47.3

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.

A FIC controller is built from groups, each described by its own DT node, and the groups of one controller share that controller's output line toward the parent. So a real devicetree has several FIC nodes on one parent GIC SPI, and a chained handler can only be installed once per parent. Cascading compounds this: an aggregating group collects several peripherals' outputs onto the line above it.

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 this instance had anything pending, so the shared-IRQ core can tell which instance on the line raised the interrupt. IRQF_NO_THREAD is set because the handler only demultiplexes to the child domain and must not be forced-threaded; all instances sharing a parent line agree on this flag, as the shared-IRQ core requires.

The handler reads the group's cause register and returns IRQ_HANDLED when any unmasked cause bit is set, IRQ_NONE otherwise. That is the signal the shared-IRQ core needs - "did this instance's hardware raise the line" - rather than the result of dispatching to the child domain, which for a domain sized exactly to the cause register always succeeds.

request_irq() can fail, unlike irq_set_chained_handler_and_data(), so add an error path for it. Set IRQ_DOMAIN_FLAG_DESTROY_GC on the domain after creating it, so irq_domain_remove() tears the generic chips down too and the single call suffices for both the chip-allocation and request_irq() failure paths.

---
v3:
- al_fic_irq_handler() no longer derives IRQ_HANDLED/IRQ_NONE from generic_handle_domain_irq(), whose return value only reports whether the hwirq to virq mapping succeeded - and since the loop iterates exactly NR_FIC_IRQS bits, which is the domain's own size, that mapping always succeeds. Return IRQ_HANDLED when the masked CAUSE snapshot is non-zero instead, which is the correct signal for a shared interrupt.
- Set IRQ_DOMAIN_FLAG_DESTROY_GC on the domain and let irq_domain_remove() free the generic chips, instead of calling irq_domain_remove_generic_chips() by hand. Both error paths now go through one label. The invalid-free fix from v2 is unaffected; only the teardown mechanism changed.
- Use of_node_full_name() in the request_irq() call.

v2:
- Fix the request_irq() error path: v1 called irq_free_generic_chip(gc), which is kfree(gc) on an interior pointer into the single allocation made by irq_domain_alloc_generic_chips() - an invalid free reachable when request_irq() fails at probe. Replace it with irq_domain_remove_generic_chips() before irq_domain_remove(), and add a commit-message paragraph explaining the teardown ordering.
- Add Co-developed-by/Signed-off-by: Talel Shenhar.
- Reworded to state the hardware reason for the shared parent (the groups of one controller share that controller's output line).

 drivers/irqchip/irq-al-fic.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

index ee06d0123b7a..4c60da8558ed 100644
@@ -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 +95,21 @@ 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);
 	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);
 
-	chained_irq_exit(irqchip, desc);
+	return pending ? IRQ_HANDLED : IRQ_NONE;
 }
 
 static int al_fic_irq_retrigger(struct irq_data *data)

@@ -140,6 +137,12 @@ static int al_fic_register(struct device_node *node,
 		return -ENOMEM;
 	}
 
+	/*
+	 * Let irq_domain_remove() free the generic chips on either error path
+	 * below, instead of calling irq_domain_remove_generic_chips() by hand.
+	 */
+	fic->domain->flags |= IRQ_DOMAIN_FLAG_DESTROY_GC;
+
 	ret = irq_alloc_domain_generic_chips(fic->domain,
 					     NR_FIC_IRQS,
 					     1, of_node_full_name(fic->node),

@@ -162,9 +165,14 @@ 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,
+			  of_node_full_name(fic->node), fic);
+	if (ret) {
+		pr_err("fail to request irq (%d)\n", ret);
+		goto err_domain_remove;
+	}
+
 	return 0;
 
 err_domain_remove:

2.47.3

Thanks. I have dropped it from this patch in v4, because the patch has changed since you looked at it.

sashiko-bot flagged the v3 posting: with the parent now requested as a shared interrupt, the handler can report IRQ_HANDLED for a line this instance did not drive. IRQ_GC_INIT_MASK_CACHE seeds gc->mask_cache by reading the mask register, but only on the first child mapping - which is after request_irq(), and never happens at all for a group that has no consumer in the devicetree. Until then the cache reads 0 and every latched cause bit passes the handler's filter.

I checked it against the controller's register specification: the mask registers gate the controller's output, not the cause latch, so a masked source still latches its bit. There are groups in our devicetrees with no consumer sharing a parent with groups that have one, so for those the cache would stay 0 for the lifetime of the system.

So al_fic_register() now seeds the cache from the value al_fic_wire_init() programmed, before the parent is requested, and drops IRQ_GC_INIT_MASK_CACHE - nothing else writes the mask register before the first child is mapped, so the read could only ever have returned that same value.

That is a functional change, so the tag came off rather than being carried over. The fix is in v4, which I will post shortly.

Thanks,
Eliav

The block this driver calls a FIC is the generic Annapurna Labs interrupt controller. It is built from groups of up to 32 triggers each; the number of groups differs from one controller to another, and each group has its own 0x40 register block.

A node in this binding describes one group, not a whole controller. reg points at that group's 0x40 block, and the 32 hwirqs of the domain are that group's triggers. A controller with several groups appears as several nodes, and controllers cascade when a tree needs more triggers than one controller has.

A group has one cause register and three mask registers, which decide which output a set cause bit drives:

  0x10  info mask    gates the info output
  0x2c  error mask   gates the error output
  0x34  fatal mask   gates the fatal output

The three outputs are aggregated into three separate interrupt trees (info, error, fatal); mapping one event to more than one severity is forbidden by the interrupt methodology, so a group belongs to exactly one tree. Which output a group drives is fixed when the SoC is wired and is not discoverable from any register, so it must be described in the devicetree.

The error and fatal outputs, and their mask registers, exist only on controller revisions that implement them; earlier revisions provide the info output only. A controller reports its revision in the group control register (bits 29-28), so the revision itself does not need to appear in the devicetree and no per-revision compatible string is needed.

Describe which output a group drives with a new optional property, amazon,al-fic-mask (info, error or fatal; default info).

---
v3: no change. Added Reviewed-by: Radu Rendec and Acked-by: Conor Dooley.

v2: redesigned in response to Conor Dooley's review of v1.
- Drop the two proposed per-output compatible strings (amazon,al-fic-error / amazon,al-fic-fatal). A node describes one group, and a controller reports its revision in the group control register (bits 29-28), so no per-revision or per-output compatible is needed.
- Instead add an optional amazon,al-fic-mask property (info, error, fatal; default info) selecting which output a group drives. Existing amazon,al-fic nodes keep behaving as before.
- Rewrite the commit message to describe the hardware and the group granularity, and add an example fragment to the YAML, as requested.

 .../interrupt-controller/amazon,al-fic.yaml      | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

index 26bc05dee0bc..1ebf9a427f2f 100644
@@ -24,6 +24,19 @@ properties:
   interrupts:
     maxItems: 1
 
+  amazon,al-fic-mask:
+    $ref: /schemas/types.yaml#/definitions/string
+    description:
+      Selects which of the controller's severity outputs this group drives,
+      and thus which mask register the driver programs. A group has one cause
+      register and three severity outputs - info, error and fatal - each
+      gated by its own mask register. Each output is aggregated into a
+      separate interrupt tree, and a group belongs to exactly one of them.
+      The error and fatal outputs exist only on controller revisions that
+      implement them; earlier revisions provide the info output only.
+    enum: [info, error, fatal]
+    default: info
+
 required:
   - compatible
   - reg

@@ -39,8 +52,9 @@ examples:
 
     interrupt-controller@fd8a8500 {
         compatible = "amazon,al-fic";
-        reg = <0xfd8a8500 0x1000>;
+        reg = <0xfd8a8500 0x40>;
         interrupt-controller;
         #interrupt-cells = <2>;
         interrupts = <GIC_SPI 0x0 IRQ_TYPE_LEVEL_HIGH>;
+        amazon,al-fic-mask = "error";
     };

2.47.3

FIC v2 hardware adds two interrupt outputs on top of the info output: an error output and a fatal output, each with its own mask register (AL_FIC_ERROR_MASK, AL_FIC_FATAL_MASK). A group drives exactly one of the three outputs.

Read which output a group drives from the amazon,al-fic-mask devicetree property (info, error or fatal; absent means info) and program the matching mask register. Detect the hardware revision from the CONTROL register version field (bits 28-29). The revision is not in the devicetree, so requesting the error or fatal output on a v1 device - which has neither - is rejected at probe against the register.

Name the selected output in the probe log line, in place of the "Legacy mode" text it replaces. A booted system then shows which output each group drives.

The "v1" and "v2" names are this driver's labels for the CONTROL version field encoding (0 and 1).

On v2 the error and fatal mask registers always read back as 0, regardless of their actual contents. IRQ_GC_INIT_MASK_CACHE seeds mask_cache from the mask register on the first child mapping, so on those two outputs it would seed 0: every source would appear unmasked, and the first unmask would write that 0 back and clear the whole mask register. Drop the flag for those two outputs and seed mask_cache with the value al_fic_wire_init() programmed instead. The info mask register is not affected, so the info output keeps the register-seeded mask_cache.

Reading CONTROL to get the version field turns the write that follows into a read-modify-write instead of a value built from CONTROL_MASK_MSI_X alone. Every RW bit in this register resets to 0, so the two are equivalent at probe time; the read-modify-write is kept anyway as the better practice; it costs nothing and does not depend on the reset value staying 0.

---
v3:
- Initialise gc_flags to IRQ_GC_INIT_MASK_CACHE at its declaration and only clear it on the FIC v2 error/fatal path, dropping the else branch.
- Use ~0U instead of 0xFFFFFFFF, for the mask_cache seed and for the three mask register writes.
- Explain the control register read-modify-write in the commit message. Every writable bit in that register resets to 0, so preserving the other bits is equivalent to the previous plain write at probe time. It is better practice, not a behaviour fix.

v2:
- Fix the v2 mask_cache workaround, which was dead in v1. mask_cache is not seeded until the first child mapping (irq_map_generic_chip), so the v1 override was overwritten with 0 and the first unmask then cleared the whole mask register, unmasking all 32 sources. Drop IRQ_GC_INIT_MASK_CACHE for the error and fatal outputs and seed mask_cache from the value al_fic_wire_init() programmed. Commit message rewritten to state the real timing and consequence.
- Read the output from the new amazon,al-fic-mask property (was per-output compatible in v1).
- Label the mask in the probe log line (mask=%s).

 drivers/irqchip/irq-al-fic.c | 135 ++++++++++++++++++++++++++++++++---
 1 file changed, 124 insertions(+), 11 deletions(-)

index 4c60da8558ed..68948d5464d4 100644
@@ -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_INFO_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
 

@@ -33,6 +36,37 @@ enum al_fic_state {
 	AL_FIC_CONFIGURED_RISING_EDGE,
 };
 
+/*
+ * FIC hardware revision, as reported by the CONTROL register version field
+ * (CONTROL_VERSION_ID, bits 29-28). These are this driver's names for that
+ * field's encoding.
+ */
+enum al_fic_version {
+	AL_FIC_VERSION_V1,
+	AL_FIC_VERSION_V2,
+};
+
+enum al_fic_id {
+	AL_FIC_ID_INFO,
+	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_INFO]  = AL_FIC_INFO_MASK,
+	[AL_FIC_ID_ERROR] = AL_FIC_ERROR_MASK,
+	[AL_FIC_ID_FATAL] = AL_FIC_FATAL_MASK,
+};
+
+/* amazon,al-fic-mask property value for each interrupt group */
+static const char * const al_fic_mask_name[AL_FIC_ID_MAX] = {
+	[AL_FIC_ID_INFO]  = "info",
+	[AL_FIC_ID_ERROR] = "error",
+	[AL_FIC_ID_FATAL] = "fatal",
+};
+
 struct al_fic {
 	void __iomem *base;
 	struct irq_domain *domain;

@@ -123,11 +157,30 @@ 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,
+			   enum al_fic_version version)
 {
+	enum irq_gc_flags gc_flags = IRQ_GC_INIT_MASK_CACHE;
 	struct irq_chip_generic *gc;
 	int ret;
 
+	/*
+	 * On FIC v2 the error and fatal mask registers always read back as 0,
+	 * regardless of their actual contents. IRQ_GC_INIT_MASK_CACHE seeds
+	 * mask_cache from the mask register on the first child mapping, so on
+	 * those two outputs it would seed 0 and make every source appear
+	 * unmasked - and the first unmask would then clear the whole mask
+	 * register. Suppress the seeding there and set mask_cache below to
+	 * match what al_fic_wire_init() programmed.
+	 *
+	 * The info mask register is not affected, so the info output keeps the
+	 * register-seeded mask_cache.
+	 */
+	if (version == AL_FIC_VERSION_V2 &&
+	    (fic_id == AL_FIC_ID_ERROR || fic_id == AL_FIC_ID_FATAL))
+		gc_flags = 0;
+
 	fic->domain = irq_domain_create_linear(of_fwnode_handle(node),
 					       NR_FIC_IRQS,
 					       &irq_generic_chip_ops,

@@ -147,7 +200,7 @@ static int al_fic_register(struct device_node *node,
 					     NR_FIC_IRQS,
 					     1, of_node_full_name(fic->node),
 					     handle_level_irq,
-					     0, 0, IRQ_GC_INIT_MASK_CACHE);
+					     0, 0, gc_flags);
 	if (ret) {
 		pr_err("fail to allocate generic chip (%d)\n", ret);
 		goto err_domain_remove;

@@ -155,7 +208,7 @@ 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;

@@ -165,6 +218,13 @@ static int al_fic_register(struct device_node *node,
 	gc->chip_types->chip.flags = IRQCHIP_SKIP_SET_WAKE;
 	gc->private = fic;
 
+	/*
+	 * Seed the mask cache the driver maintains itself, matching the mask
+	 * al_fic_wire_init() programmed (see the gc_flags comment above).
+	 */
+	if (!(gc_flags & IRQ_GC_INIT_MASK_CACHE))
+		gc->mask_cache = ~0U;
+
 	ret = request_irq(fic->parent_irq, al_fic_irq_handler,
 			  IRQF_NO_THREAD | IRQF_SHARED,
 			  of_node_full_name(fic->node), fic);

@@ -186,6 +246,8 @@ static int al_fic_register(struct device_node *node,
  * @node: pointer to the interrupt controller's device tree node
  * @base: mmio to fic register
  * @parent_irq: interrupt of parent
+ * @fic_id: which of the controller's outputs (info, error or fatal) this
+ *          group drives
  *
  * This API will configure the fic hardware to work in wire mode.
  * In wire mode, fic hardware is generating a wire ("wired") interrupt.

@@ -194,11 +256,13 @@ static int al_fic_register(struct device_node *node,
  */
 static struct al_fic *al_fic_wire_init(struct device_node *node,
 				       void __iomem *base,
-				       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 +272,37 @@ static struct al_fic *al_fic_wire_init(struct device_node *node,
 	fic->parent_irq = parent_irq;
 	fic->node = node;
 
+	control = readl_relaxed(fic->base + AL_FIC_CONTROL);
+	version_id = FIELD_GET(CONTROL_VERSION_ID, control);
+	if (version_id == AL_FIC_VERSION_V1 && fic_id != AL_FIC_ID_INFO) {
+		pr_err("%pOF: amazon,al-fic-mask = \"%s\" not available on FIC v1\n",
+		       node, al_fic_mask_name[fic_id]);
+		ret = -EINVAL;
+		goto err_free;
+	}
+
 	/* mask out all interrupts */
-	writel_relaxed(0xFFFFFFFF, fic->base + AL_FIC_MASK);
+	writel_relaxed(~0U, fic->base + AL_FIC_INFO_MASK);
+	if (version_id > AL_FIC_VERSION_V1) {
+		writel_relaxed(~0U, fic->base + AL_FIC_ERROR_MASK);
+		writel_relaxed(~0U, 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, version_id);
 	if (ret) {
 		pr_err("fail to register irqchip\n");
 		goto err_free;
 	}
 
-	pr_info("%pOF initialized successfully in Legacy mode (parent-irq=%u)\n",
-		node, parent_irq);
+	pr_info("%pOF initialized successfully (mask=%s parent-irq=%u)\n",
+		node, al_fic_mask_name[fic_id], parent_irq);
 
 	return fic;
 

@@ -232,11 +311,38 @@ static struct al_fic *al_fic_wire_init(struct device_node *node,
 	return ERR_PTR(ret);
 }
 
+/*
+ * Parse the amazon,al-fic-mask property into an enum al_fic_id, selecting
+ * which of the controller's outputs this group drives. The property is
+ * optional; an absent property means the info output.
+ */
+static int al_fic_parse_mask(struct device_node *node, enum al_fic_id *fic_id)
+{
+	const char *mask;
+	int ret;
+
+	ret = of_property_read_string(node, "amazon,al-fic-mask", &mask);
+	if (ret == -EINVAL) {
+		*fic_id = AL_FIC_ID_INFO;
+		return 0;
+	}
+	if (ret)
+		return ret;
+
+	ret = match_string(al_fic_mask_name, AL_FIC_ID_MAX, mask);
+	if (ret < 0)
+		return ret;
+
+	*fic_id = ret;
+	return 0;
+}
+
 static int __init al_fic_init_dt(struct device_node *node,
 				 struct device_node *parent)
 {
 	int ret;
 	void __iomem *base;
+	enum al_fic_id fic_id;
 	unsigned int parent_irq;
 	struct al_fic *fic;
 

@@ -245,6 +351,12 @@ static int __init al_fic_init_dt(struct device_node *node,
 		return -EINVAL;
 	}
 
+	ret = al_fic_parse_mask(node, &fic_id);
+	if (ret) {
+		pr_err("%pOF: invalid amazon,al-fic-mask\n", node);
+		return ret;
+	}
+
 	base = of_iomap(node, 0);
 	if (!base) {
 		pr_err("%pOF: fail to map memory\n", node);

@@ -260,7 +372,8 @@ static int __init al_fic_init_dt(struct device_node *node,
 
 	fic = al_fic_wire_init(node,
 			       base,
-			       parent_irq);
+			       parent_irq,
+			       fic_id);
 	if (IS_ERR(fic)) {
 		pr_err("%pOF: fail to initialize irqchip (%lu)\n",
 		       node, PTR_ERR(fic));

2.47.3

FIC v3 reports version id 2 in the control register version field. It exposes the same info/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.

---
v3: no change. Added Reviewed-by: Radu Rendec.

v2: the "erratum fixed from v3 onwards" code comment moved here (where
AL_FIC_VERSION_V3 is introduced) from the FIC v2 patch, so the claim that v3 keeps the register-seeded mask_cache has its code in the same commit.

 drivers/irqchip/irq-al-fic.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

index 68948d5464d4..84cb14615d56 100644
@@ -44,6 +44,7 @@ enum al_fic_state {
 enum al_fic_version {
 	AL_FIC_VERSION_V1,
 	AL_FIC_VERSION_V2,
+	AL_FIC_VERSION_V3,
 };
 
 enum al_fic_id {

@@ -174,8 +175,8 @@ static int al_fic_register(struct device_node *node,
 	 * register. Suppress the seeding there and set mask_cache below to
 	 * match what al_fic_wire_init() programmed.
 	 *
-	 * The info mask register is not affected, so the info output keeps the
-	 * register-seeded mask_cache.
+	 * The info mask register is not affected, and the erratum is fixed
+	 * from v3 onwards, so those paths keep the register-seeded mask_cache.
 	 */
 	if (version == AL_FIC_VERSION_V2 &&
 	    (fic_id == AL_FIC_ID_ERROR || fic_id == AL_FIC_ID_FATAL))

2.47.3

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 pr_warn_once() is emitted when the requested affinity differs from the parent's current affinity, giving visibility without failing the caller.

---
v3: no change. The question Radu Rendec raised on this patch - whether an
unconditional IRQ_SET_MASK_OK_DONE is the right contract, or whether it should fail with -EINVAL - is still under discussion on the v2 thread and is answered there.

v2: add Co-developed-by/Signed-off-by: Talel Shenhar. No code change from

    v1.

 drivers/irqchip/irq-al-fic.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

index 84cb14615d56..36954ba4f4f2 100644
@@ -157,6 +157,36 @@ 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))
+		pr_warn_once("%pOF: affinity change requested but FIC is fixed to parent IRQ %u CPU routing\n",
+			     fic->node, 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,

@@ -216,6 +246,7 @@ 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