From 6ad66e28d1fccc07290b4a4f6976d5e23e9d7b0f Mon Sep 17 00:00:00 2001
From: thorpej <thorpej@NetBSD.org>
Date: Mon, 28 Dec 2020 15:08:06 +0000
Subject: [PATCH] The i2c-mux bindings specify that if the mux device has a
 child node named "i2c-mux", then it is that node that is the parent of the
 i2c bus children. This is to accommodate mux devices that may also have other
 kinds of child nodes in addition to i2c bus child nodes.

---
 sys/dev/fdt/i2cmux_fdt.c | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/sys/dev/fdt/i2cmux_fdt.c b/sys/dev/fdt/i2cmux_fdt.c
index 053a123c8c15..5c9f8c325e82 100644
--- a/sys/dev/fdt/i2cmux_fdt.c
+++ b/sys/dev/fdt/i2cmux_fdt.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: i2cmux_fdt.c,v 1.2 2020/12/23 16:04:42 thorpej Exp $	*/
+/*	$NetBSD: i2cmux_fdt.c,v 1.3 2020/12/28 15:08:06 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 2020 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: i2cmux_fdt.c,v 1.2 2020/12/23 16:04:42 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: i2cmux_fdt.c,v 1.3 2020/12/28 15:08:06 thorpej Exp $");
 
 #include <sys/types.h>
 #include <sys/device.h>
@@ -94,6 +94,7 @@ struct iicmux_bus {
 struct iicmux_softc {
 	device_t			sc_dev;
 	int				sc_phandle;
+	int				sc_i2c_mux_phandle;
 	const struct iicmux_config *	sc_config;
 	i2c_tag_t			sc_i2c_parent;
 	struct iicmux_bus *		sc_busses;
@@ -317,10 +318,24 @@ static const struct of_compat_data compat_data[] = {
 static int
 iicmux_count_children(struct iicmux_softc * const sc)
 {
+	char name[32];
 	int child, count;
 
-	for (child = OF_child(sc->sc_phandle), count = 0; child;
+ restart:
+	for (child = OF_child(sc->sc_i2c_mux_phandle), count = 0; child;
 	     child = OF_peer(child)) {
+		if (OF_getprop(child, "name", name, sizeof(name)) <= 0) {
+			continue;
+		}
+		if (strcmp(name, "i2c-mux") == 0) {
+			/*
+			 * The node we encountered is the acutal parent
+			 * of the i2c bus children.  Stash its phandle
+			 * and restart the enumeration.
+			 */
+			sc->sc_i2c_mux_phandle = child;
+			goto restart;
+		}
 		count++;
 	}
 
@@ -394,6 +409,14 @@ iicmux_fdt_attach(device_t const parent, device_t const self, void * const aux)
 	aprint_naive("\n");
 	aprint_normal(": %s I2C mux\n", sc->sc_config->desc);
 
+	/*
+	 * We start out assuming that the i2c bus nodes are children of
+	 * our own node.  We'll adjust later if we encounter an "i2c-mux"
+	 * node when counting our children.  If we encounter such a node,
+	 * then it's that node that is the parent of the i2c bus children.
+	 */
+	sc->sc_i2c_mux_phandle = sc->sc_phandle;
+
 	sc->sc_i2c_parent = fdtbus_i2c_acquire(sc->sc_phandle, "i2c-parent");
 	if (sc->sc_i2c_parent == NULL) {
 		aprint_error_dev(sc->sc_dev, "unable to acquire i2c-parent\n");
@@ -409,7 +432,7 @@ iicmux_fdt_attach(device_t const parent, device_t const self, void * const aux)
 	    KM_SLEEP);
 
 	int child, idx;
-	for (child = OF_child(sc->sc_phandle), idx = 0; child;
+	for (child = OF_child(sc->sc_i2c_mux_phandle), idx = 0; child;
 	     child = OF_peer(child), idx++) {
 		KASSERT(idx < nchildren);
 		iicmux_attach_bus(sc, child, idx);