[PATCH] of: property: Add fw_devlink support for interrupt-map property

[Anup Patel <apatel@ventanamicro.com>]

Some of the PCI controllers (such as generic PCI host controller)
use "interrupt-map" DT property to describe the mapping between
PCI endpoints and PCI interrupt pins.

Currently, there is no fw_devlink created based on "interrupt-map"
DT property so interrupt controller is not guaranteed to be probed
before PCI host controller. This mainly affects RISC-V platforms
where both PCI host controller and interrupt controllers are probed
as regular platform devices.

This creates fw_devlink between consumers (PCI host controller) and
supplier (interrupt controller) based on "interrupt-map" DT property.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
---
 drivers/of/property.c | 53 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index a6358ee99b74..ccbbb651a89a 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1311,6 +1311,58 @@ static struct device_node *parse_interrupts(struct device_node *np,
 	return of_irq_parse_one(np, index, &sup_args) ? NULL : sup_args.np;
 }
 
+static struct device_node *parse_interrupt_map(struct device_node *np,
+					       const char *prop_name, int index)
+{
+	struct device_node *tn, *ipar, *supnp = NULL;
+	u32 addrcells, intcells, cells;
+	const __be32 *imap, *imap_end;
+	int i, imaplen;
+
+	if (!IS_ENABLED(CONFIG_OF_IRQ))
+		return NULL;
+
+	if (strcmp(prop_name, "interrupt-map"))
+		return NULL;
+
+	ipar = of_node_get(np);
+	do {
+		if (!of_property_read_u32(ipar, "#interrupt-cells", &intcells))
+			break;
+		tn = ipar;
+		ipar = of_irq_find_parent(ipar);
+		of_node_put(tn);
+	} while (ipar);
+	if (!ipar)
+		return NULL;
+	addrcells = of_bus_n_addr_cells(ipar);
+	of_node_put(ipar);
+
+	imap = of_get_property(np, "interrupt-map", &imaplen);
+	if (!imap || imaplen <= (addrcells + intcells))
+		return NULL;
+	imap_end = imap + imaplen;
+
+	for (i = 0; i <= index && imap < imap_end; i++) {
+		if (supnp)
+			of_node_put(supnp);
+
+		imap += addrcells;
+		imap += intcells;
+
+		supnp = of_find_node_by_phandle(be32_to_cpu(imap[0]));
+		if (!supnp)
+			return NULL;
+		imap += 1;
+
+		if (of_property_read_u32(supnp, "#interrupt-cells", &cells))
+			return NULL;
+		imap += cells;
+	}
+
+	return supnp;
+}
+
 static struct device_node *parse_remote_endpoint(struct device_node *np,
 						 const char *prop_name,
 						 int index)
@@ -1359,6 +1411,7 @@ static const struct supplier_bindings of_supplier_bindings[] = {
 	{ .parse_prop = parse_msi_parent, },
 	{ .parse_prop = parse_gpio_compat, },
 	{ .parse_prop = parse_interrupts, },
+	{ .parse_prop = parse_interrupt_map, },
 	{ .parse_prop = parse_regulators, },
 	{ .parse_prop = parse_gpio, },
 	{ .parse_prop = parse_gpios, },
-- 
2.34.1