[PATCH v3 1/8] of/irq: Introduce for_each_of_imap_item

Herve Codina (Schneider Electric)
2025-09-18T10:40:30Z

for_each_of_imap_item is an iterator designed to help a driver to parse
an interrupt-map property.

Indeed some drivers need to know details about the interrupt mapping
described in the device-tree in order to set internal registers
accordingly.

Signed-off-by: Herve Codina (Schneider Electric) <herve.codina@bootlin.com>
---
drivers/of/irq.c | 70 ++++++++++++++++++++++++++++++++++++++++++
include/linux/of_irq.h | 41 ++++++++++++++++++++++++-
2 files changed, 110 insertions(+), 1 deletion(-)

diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index 74aaea61de13..0723ae4153a0 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -157,6 +157,76 @@ const __be32 *of_irq_parse_imap_parent(const __be32 *imap, int len, struct of_ph
return imap;
}

+int of_imap_parser_init(struct of_imap_parser *parser, struct device_node *node,
+ struct of_imap_item *item)
+{
+ int imaplen;
+ u32 tmp;
+ int ret;
+
+ /*
+ * parent_offset is the offset where the parent part is starting.
+ * In other words, the offset where the parent interrupt controller
+ * phandle is present.
+ *
+ * Compute this offset (child #interrupt-cells + child #address-cells)
+ */
+ parser->parent_offset = of_bus_n_addr_cells(node);
+
+ ret = of_property_read_u32(node, "#interrupt-cells", &tmp);
+ if (ret)
+ return ret;
+
+ parser->parent_offset += tmp;
+
+ if (WARN(parser->parent_offset > ARRAY_SIZE(item->child_imap),
+ "child part size = %u, cannot fit in array of %zu items",
+ parser->parent_offset, ARRAY_SIZE(item->child_imap)))
+ return -EINVAL;
+
+ parser->imap = of_get_property(node, "interrupt-map", &imaplen);
+ if (!parser->imap)
+ return -ENOENT;
+
+ imaplen /= sizeof(*parser->imap);
+ parser->imap_end = parser->imap + imaplen;
+
+ memset(item, 0, sizeof(*item));
+ item->child_imap_count = parser->parent_offset;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(of_imap_parser_init);
+
+struct of_imap_item *of_imap_parser_one(struct of_imap_parser *parser,
+ struct of_imap_item *item)
+{
+ const __be32 *imap_parent, *imap_next;
+ int i;
+
+ /* Release previously get parent node */
+ of_node_put(item->parent_args.np);
+
+ if (parser->imap + parser->parent_offset + 1 >= parser->imap_end)
+ return NULL;
+
+ imap_parent = parser->imap + parser->parent_offset;
+
+ imap_next = of_irq_parse_imap_parent(imap_parent,
+ parser->imap_end - imap_parent,
+ &item->parent_args);
+ if (!imap_next)
+ return NULL;
+
+ for (i = 0; i < parser->parent_offset; i++)
+ item->child_imap[i] = be32_to_cpu(*(parser->imap + i));
+
+ parser->imap = imap_next;
+
+ return item;
+}
+EXPORT_SYMBOL_GPL(of_imap_parser_one);
+
/**
* of_irq_parse_raw - Low level interrupt tree parsing
* @addr: address specifier (start of "reg" property of the device) in be32 format
diff --git a/include/linux/of_irq.h b/include/linux/of_irq.h
index a480063c9cb1..65f2c97147de 100644
--- a/include/linux/of_irq.h
+++ b/include/linux/of_irq.h
@@ -11,6 +11,30 @@

typedef int (*of_irq_init_cb_t)(struct device_node *, struct device_node *);

+struct of_imap_parser {
+ struct device_node *node;
+ const __be32 *imap;
+ const __be32 *imap_end;
+ u32 parent_offset;
+};
+
+struct of_imap_item {
+ struct of_phandle_args parent_args;
+ u32 child_imap_count;
+ u32 child_imap[16]; /* Arbitrary size.
+ * Should be #address-cells + #interrupt-cells but
+ * avoid using allocation and so, expect that 16
+ * should be enough
+ */
+};
+
+/*
+ * If the iterator is exited prematurely (break, goto, return) of_node_put() has
+ * to be called on item.parent_args.np
+ */
+#define for_each_of_imap_item(parser, item) \
+ for (; of_imap_parser_one(parser, item);)
+
/*
* Workarounds only applied to 32bit powermac machines
*/
@@ -47,6 +71,11 @@ extern int of_irq_get_byname(struct device_node *dev, const char *name);
extern int of_irq_to_resource_table(struct device_node *dev,
struct resource *res, int nr_irqs);
extern struct device_node *of_irq_find_parent(struct device_node *child);
+extern int of_imap_parser_init(struct of_imap_parser *parser,
+ struct device_node *node,
+ struct of_imap_item *item);
+extern struct of_imap_item *of_imap_parser_one(struct of_imap_parser *parser,
+ struct of_imap_item *item);
extern struct irq_domain *of_msi_get_domain(struct device *dev,
const struct device_node *np,
enum irq_domain_bus_token token);
@@ -86,7 +115,17 @@ static inline void *of_irq_find_parent(struct device_node *child)
{
return NULL;
}
-
+static inline int of_imap_parser_init(struct of_imap_parser *parser,
+ struct device_node *node,
+ struct of_imap_item *item)
+{
+ return -ENOSYS;
+}
+static inline struct of_imap_item *of_imap_parser_one(struct of_imap_parser *parser,
+ struct of_imap_item *item)
+{
+ return NULL;
+}
static inline struct irq_domain *of_msi_get_domain(struct device *dev,
struct device_node *np,
enum irq_domain_bus_token token)
--
2.51.0