[PATCH v4] of: property: Add fw_devlink support for interrupt-map property

[Anup Patel]

Some of the PCI host controllers (such as generic PCI host controller)
use "interrupt-map" DT property to describe the mapping between PCI
endpoints and PCI interrupt pins. This is the only case where the
interrupts are not described in DT.

Currently, there is no fw_devlink created based on "interrupt-map"
DT property so interrupt controller is not guaranteed to be probed
before the PCI host controller. This affects every platform 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 at ventanamicro.com>
Reviewed-by: Saravana Kannan <saravanak at google.com>
---
Changes since v3:
- Added a comment about of_irq_parse_raw()
- Removed redundant NULL assignments to sup_args.np
Changes since v2:
- No need for a loop to find #interrupt-cells property value
- Fix node de-reference leak when index is greater than number
  of entries in interrupt-map property
Changes since v1:
- Updated commit description based on Rob's suggestion
- Use of_irq_parse_raw() for parsing interrupt-map DT property
---
 drivers/of/property.c | 52 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/drivers/of/property.c b/drivers/of/property.c
index a6358ee99b74..2d749a18b037 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -1311,6 +1311,57 @@ 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)
+{
+	const __be32 *imap, *imap_end, *addr;
+	struct of_phandle_args sup_args;
+	u32 addrcells, intcells;
+	int i, imaplen;
+
+	if (!IS_ENABLED(CONFIG_OF_IRQ))
+		return NULL;
+
+	if (strcmp(prop_name, "interrupt-map"))
+		return NULL;
+
+	if (of_property_read_u32(np, "#interrupt-cells", &intcells))
+		return NULL;
+	addrcells = of_bus_n_addr_cells(np);
+
+	imap = of_get_property(np, "interrupt-map", &imaplen);
+	if (!imap || imaplen <= (addrcells + intcells))
+		return NULL;
+	imap_end = imap + imaplen;
+
+	while (imap < imap_end) {
+		addr = imap;
+		imap += addrcells;
+
+		sup_args.np = np;
+		sup_args.args_count = intcells;
+		for (i = 0; i < intcells; i++)
+			sup_args.args[i] = be32_to_cpu(imap[i]);
+		imap += intcells;
+
+		/*
+		 * Upon success, the function of_irq_parse_raw() returns
+		 * interrupt controller DT node pointer in sup_args.np.
+		 */
+		if (of_irq_parse_raw(addr, &sup_args))
+			return NULL;
+
+		if (!index)
+			return sup_args.np;
+
+		of_node_put(sup_args.np);
+		imap += sup_args.args_count + 1;
+		index--;
+	}
+
+	return NULL;
+}
+
 static struct device_node *parse_remote_endpoint(struct device_node *np,
 						 const char *prop_name,
 						 int index)
@@ -1359,6 +1410,7 @@ 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