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>

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 8eee986..c1ae719 100644 (file)
--- a/drivers/i2c/i2c-mux.c
+++ b/drivers/i2c/i2c-mux.c
@@ -255,6 +255,10 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
        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 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
         * 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);
        }
 
        /*

diff --git a/include/linux/i2c-mux.h b/include/linux/i2c-mux.h
index d4c1d12..bd74d57 100644 (file)
--- a/include/linux/i2c-mux.h
+++ b/include/linux/i2c-mux.h
@@ -32,7 +32,9 @@
 struct i2c_mux_core {
        struct i2c_adapter *parent;
        struct device *dev;
-       bool mux_locked;
+       unsigned int mux_locked:1;
+       unsigned int arbitrator:1;
+       unsigned int gate:1;
 
        void *priv;
 
@@ -51,7 +53,9 @@ struct i2c_mux_core *i2c_mux_alloc(struct i2c_adapter *parent,
                                   int (*deselect)(struct i2c_mux_core *, u32));
 
 /* flags for i2c_mux_alloc */
-#define I2C_MUX_LOCKED BIT(0)
+#define I2C_MUX_LOCKED     BIT(0)
+#define I2C_MUX_ARBITRATOR BIT(1)
+#define I2C_MUX_GATE       BIT(2)
 
 static inline void *i2c_mux_priv(struct i2c_mux_core *muxc)
 {