From 7fcdbfc9baf5c5b6ba920df2b0afc1ce1ee4e58f Mon Sep 17 00:00:00 2001
From: Andrew Turner <andrew@FreeBSD.org>
Date: Mon, 21 Jul 2025 12:46:12 +0100
Subject: [PATCH] dev/ofw: Add interrupt-map support

Follow interrupt-map properties until either an interrupt controller or
invalid node is found. In the former case return the translated details
for the interrupt controller driver to decode. In the latter case return
0 as an error.

Tested on the Arm DTS files that use interrupt-maps and with a
userspace test.

Sponsored by:	Arm Ltd
Differential Revision:	https://reviews.freebsd.org/D51257
---
 sys/dev/ofw/ofw_bus_subr.c | 101 ++++++++++++++++++++++++++++++++++---
 1 file changed, 95 insertions(+), 6 deletions(-)

diff --git a/sys/dev/ofw/ofw_bus_subr.c b/sys/dev/ofw/ofw_bus_subr.c
index 4d0479dfb95..b99d784929b 100644
--- a/sys/dev/ofw/ofw_bus_subr.c
+++ b/sys/dev/ofw/ofw_bus_subr.c
@@ -634,11 +634,89 @@ ofw_bus_find_iparent(phandle_t node)
 	return (iparent);
 }
 
+static phandle_t
+ofw_bus_search_iparent(phandle_t node)
+{
+	phandle_t iparent;
+
+	do {
+		if (OF_getencprop(node, "interrupt-parent", &iparent,
+		    sizeof(iparent)) > 0) {
+			node = OF_node_from_xref(iparent);
+		} else {
+			node = OF_parent(node);
+		}
+		if (node == 0)
+			return (0);
+	} while (!OF_hasprop(node, "#interrupt-cells"));
+
+	return (OF_xref_from_node(node));
+}
+
+static int
+ofw_bus_traverse_imap(phandle_t inode, phandle_t node, uint32_t *intr,
+    int intrsz, pcell_t *res, int ressz, phandle_t *iparentp)
+{
+	struct ofw_bus_iinfo ii;
+	void *reg;
+	uint32_t *intrp;
+	phandle_t iparent;
+	int rv = 0;
+
+	/* We already have an interrupt controller */
+	if (OF_hasprop(node, "interrupt-controller"))
+		return (0);
+
+	intrp = malloc(intrsz, M_OFWPROP, M_WAITOK);
+	memcpy(intrp, intr, intrsz);
+
+	while (true) {
+		/* There is no interrupt-map to follow */
+		if (!OF_hasprop(inode, "interrupt-map")) {
+			free(intrp, M_OFWPROP);
+			return (0);
+		}
+
+		memset(&ii, 0, sizeof(ii));
+		ofw_bus_setup_iinfo(inode, &ii, sizeof(cell_t));
+
+		reg = NULL;
+		if (ii.opi_addrc > 0)
+			reg = malloc(ii.opi_addrc, M_OFWPROP, M_WAITOK);
+
+		rv = ofw_bus_lookup_imap(node, &ii, reg, ii.opi_addrc, intrp,
+		    intrsz, res, ressz, &iparent);
+
+		free(reg, M_OFWPROP);
+		free(ii.opi_imap, M_OFWPROP);
+		free(ii.opi_imapmsk, M_OFWPROP);
+		free(intrp, M_OFWPROP);
+
+		if (rv == 0)
+			return (0);
+
+		node = inode;
+		inode = OF_node_from_xref(iparent);
+
+		/* Stop when we have an interrupt controller */
+		if (OF_hasprop(inode, "interrupt-controller")) {
+			*iparentp = iparent;
+			return (rv);
+		}
+
+		intrsz = rv * sizeof(pcell_t);
+		intrp = malloc(intrsz, M_OFWPROP, M_WAITOK);
+		memcpy(intrp, res, intrsz);
+	}
+}
+
 int
 ofw_bus_intr_to_rl(device_t dev, phandle_t node,
     struct resource_list *rl, int *rlen)
 {
-	phandle_t iparent;
+	phandle_t iparent, iparent_node;
+	uint32_t result[16];
+	uint32_t intrpcells, *intrp;
 	uint32_t icells, *intr;
 	int err, i, irqnum, nintr, rid;
 	bool extended;
@@ -646,15 +724,16 @@ ofw_bus_intr_to_rl(device_t dev, phandle_t node,
 	nintr = OF_getencprop_alloc_multi(node, "interrupts",  sizeof(*intr),
 	    (void **)&intr);
 	if (nintr > 0) {
-		iparent = ofw_bus_find_iparent(node);
+		iparent = ofw_bus_search_iparent(node);
 		if (iparent == 0) {
 			device_printf(dev, "No interrupt-parent found, "
 			    "assuming direct parent\n");
 			iparent = OF_parent(node);
 			iparent = OF_xref_from_node(iparent);
 		}
-		if (OF_searchencprop(OF_node_from_xref(iparent), 
-		    "#interrupt-cells", &icells, sizeof(icells)) == -1) {
+		iparent_node = OF_node_from_xref(iparent);
+		if (OF_searchencprop(iparent_node, "#interrupt-cells", &icells,
+		    sizeof(icells)) == -1) {
 			device_printf(dev, "Missing #interrupt-cells "
 			    "property, assuming <1>\n");
 			icells = 1;
@@ -677,7 +756,8 @@ ofw_bus_intr_to_rl(device_t dev, phandle_t node,
 	for (i = 0; i < nintr; i += icells) {
 		if (extended) {
 			iparent = intr[i++];
-			if (OF_searchencprop(OF_node_from_xref(iparent), 
+			iparent_node = OF_node_from_xref(iparent);
+			if (OF_searchencprop(iparent_node,
 			    "#interrupt-cells", &icells, sizeof(icells)) == -1) {
 				device_printf(dev, "Missing #interrupt-cells "
 				    "property\n");
@@ -691,7 +771,16 @@ ofw_bus_intr_to_rl(device_t dev, phandle_t node,
 				break;
 			}
 		}
-		irqnum = ofw_bus_map_intr(dev, iparent, icells, &intr[i]);
+
+		intrp = &intr[i];
+		intrpcells = ofw_bus_traverse_imap(iparent_node, node, intrp,
+		    icells * sizeof(intr[0]), result, sizeof(result), &iparent);
+		if (intrpcells > 0)
+			intrp = result;
+		else
+			intrpcells = icells;
+
+		irqnum = ofw_bus_map_intr(dev, iparent, intrpcells, intrp);
 		resource_list_add(rl, SYS_RES_IRQ, rid++, irqnum, irqnum, 1);
 	}
 	if (rlen != NULL)