Re: [PATCH RFC 02/11] ACPI: Introduce irq_get() for static fwnodes

On Mon, Sep 28, 2026 at 04:24:18PM -0700, Ashok Raj wrote:

On Fri, Sep 25, 2026 at 09:48:01AM +0200, Lorenzo Pieralisi wrote:

quoted

To describe and map GSIs for firmware nodes created out of ACPI static
table entries in a uniform way it is required to define some standard
properties and attach them to ACPI static fwnode as secondary nodes.

Define properties names to describe GSIs and their trigger-mode/polarity,
and implement an irq_get() callback for static fwnodes so that core code
can retrieve and map IRQs for ACPI static fwnodes in standard manner.

An empty stub for property_read_string_array() is also added, so that
the fwnode_irq_get_byname() interface falls back (through
fwnode_property_read_string_array()) to the secondary
fwnode to grab the "interrupt-names" property.

Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Bartosz Golaszewski <brgl@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
---
 drivers/acpi/property.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/acpi.h    |  4 +++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 8ee5a1f0eb48..c609100c08db 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c

@@ -1766,7 +1766,74 @@ static int acpi_fwnode_irq_get(const struct fwnode_handle *fwnode,
 
 DECLARE_ACPI_FWNODE_OPS(acpi_device_fwnode_ops);
 DECLARE_ACPI_FWNODE_OPS(acpi_data_fwnode_ops);
-const struct fwnode_operations acpi_static_fwnode_ops;
+
+static int acpi_static_fwnode_read_u32_prop_index(const struct fwnode_handle *fwnode,
+						  const char *propname,
+						  unsigned int index, u32 *value)
+{
+	u32 *values;
+	int ret, count;
+
+	count = fwnode_property_count_u32(fwnode, propname);
+	if (count < 0)
+		return count;
+
+	if (index >= count)
+		return -ENOENT;
+
+	values = kcalloc(count, sizeof(*values), GFP_KERNEL);
+	if (!values)
+		return -ENOMEM;
+
+	ret = fwnode_property_read_u32_array(fwnode, propname, values, count);
+	if (!ret)
+		*value = values[index];
+

You lookup with a propname, and then qualify with and index? is it
possible to have the different index but same propname? 

What is the question :) ? It is to retrieve a property value at a specific
index.

Alternately you can send the list to caller and they can use the ones
they need?

quoted

+	kfree(values);
+	return ret;
+}
+
+static int acpi_static_fwnode_read_string_array(const struct fwnode_handle *fwnode,
+						const char *propname,
+						const char **val, size_t nval)
+{
+	/* Route string handling to secondary software nodes */
+	return -EINVAL;
+}
+
+static int acpi_static_fwnode_irq_get(const struct fwnode_handle *fwnode,
+				      unsigned int index)
+{
+	u32 gsi, trigger, polarity;
+	int ret;
+
+	if (!fwnode->secondary)
+		return -ENODEV;
+
+	fwnode = fwnode->secondary;
+
+	ret = acpi_static_fwnode_read_u32_prop_index(fwnode, ACPI_IRQ_PROP_GSI,
+						index, &gsi);
+	if (ret)
+		return ret == -ENOENT ? -ENXIO : ret;
+
+	ret = acpi_static_fwnode_read_u32_prop_index(fwnode, ACPI_IRQ_PROP_GSI_TRIGGER,
+						index, &trigger);
+	if (ret)
+		return ret == -ENOENT ? -ENXIO : ret;
+
+	ret = acpi_static_fwnode_read_u32_prop_index(fwnode, ACPI_IRQ_PROP_GSI_POLARITY,
+						index, &polarity);
+	if (ret)
+		return ret == -ENOENT ? -ENXIO : ret;

Consolidate return to one place? 

Yes it can (and trigger and polarity can be just one property "flags", FWIW),
if we agree that's what will do, which I doubt.

Thanks,
Lorenzo