commit b2d57b56047b99f2992fc958d7ac5ead283e9088
author Peter Rosin <peda@axentia.se> Sat Jul 09 21:53:42 2016 +0200
committer Peter Rosin <peda@axentia.se> Thu Aug 25 22:11:02 2016 +0200
tree b5df552ab814d3c1fb852a941b361b767cf14015
parent 8f7720b950cf42d316fe5b625867e163a260a83c

i2c: mux: add support for 'i2c-mux', 'i2c-arb' and 'i2c-gate' DT subnodes

Backwards compatibility is preserved; the subnodes are in practice
optional.

However, the mux core needs to know what subnode it should examine, so add
a couple of new flags for i2c_mux_alloc for this purpose.

The rule is that if the mux core finds a 'reg' property in the appropriate
subnode, e.g. if 'reg' exists in the 'i2c-mux' subnode, then the mux core
will assume that this is an old style entry and not an i2c-mux subnode
(correspondingly for arbitrators and gates with 'i2c-arb' and 'i2c-gate').

Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Peter Rosin <peda@axentia.se>

drivers/i2c/i2c-mux.c

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 8eee986..c1ae719 100644
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -255,6 +255,10 @@
 	muxc->dev = dev;
 	if (flags & I2C_MUX_LOCKED)
 		muxc->mux_locked = true;
+	if (flags & I2C_MUX_ARBITRATOR)
+		muxc->arbitrator = true;
+	if (flags & I2C_MUX_GATE)
+		muxc->gate = true;
 	muxc->select = select;
 	muxc->deselect = deselect;
 	muxc->max_adapters = max_adapters;
@@ -335,18 +339,42 @@
 	 * nothing if !CONFIG_OF.
 	 */
 	if (muxc->dev->of_node) {
-		struct device_node *child;
+		struct device_node *dev_node = muxc->dev->of_node;
+		struct device_node *mux_node, *child = NULL;
 		u32 reg;
 
-		for_each_child_of_node(muxc->dev->of_node, child) {
-			ret = of_property_read_u32(child, "reg", &reg);
-			if (ret)
-				continue;
-			if (chan_id == reg) {
-				priv->adap.dev.of_node = child;
-				break;
+		if (muxc->arbitrator)
+			mux_node = of_get_child_by_name(dev_node, "i2c-arb");
+		else if (muxc->gate)
+			mux_node = of_get_child_by_name(dev_node, "i2c-gate");
+		else
+			mux_node = of_get_child_by_name(dev_node, "i2c-mux");
+
+		if (mux_node) {
+			/* A "reg" property indicates an old-style DT entry */
+			if (!of_property_read_u32(mux_node, "reg", &reg)) {
+				of_node_put(mux_node);
+				mux_node = NULL;
 			}
 		}
+
+		if (!mux_node)
+			mux_node = of_node_get(dev_node);
+		else if (muxc->arbitrator || muxc->gate)
+			child = of_node_get(mux_node);
+
+		if (!child) {
+			for_each_child_of_node(mux_node, child) {
+				ret = of_property_read_u32(child, "reg", &reg);
+				if (ret)
+					continue;
+				if (chan_id == reg)
+					break;
+			}
+		}
+
+		priv->adap.dev.of_node = child;
+		of_node_put(mux_node);
 	}
 
 	/*