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

[Lorenzo Pieralisi]

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@xxxxxxxxxx>
Cc: Bartosz Golaszewski <brgl@xxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
---
 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];
+
+	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;
+
+	return acpi_register_gsi(NULL, gsi, trigger, polarity);
+}
+
+const struct fwnode_operations acpi_static_fwnode_ops = {
+	.property_read_string_array = acpi_static_fwnode_read_string_array,
+	.irq_get = acpi_static_fwnode_irq_get,
+};
 
 bool is_acpi_device_node(const struct fwnode_handle *fwnode)
 {
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index ddacac812094..749cbbdcad08 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -378,6 +378,10 @@ int acpi_register_gsi (struct device *dev, u32 gsi, int triggering, int polarity
 int acpi_gsi_to_irq (u32 gsi, unsigned int *irq);
 int acpi_isa_irq_to_gsi (unsigned isa_irq, u32 *gsi);
 
+#define ACPI_IRQ_PROP_GSI		"linux,acpi-gsi"
+#define ACPI_IRQ_PROP_GSI_TRIGGER	"linux,acpi-gsi-trigger"
+#define ACPI_IRQ_PROP_GSI_POLARITY	"linux,acpi-gsi-polarity"
+
 typedef struct fwnode_handle *(*acpi_gsi_domain_disp_fn)(u32);
 typedef acpi_handle (*acpi_gsi_handle_disp_fn)(u32);
 

-- 
2.54.0