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Subject[PATCH v2 5/8] i2c: mux: add support for 'i2c-mux', 'i2c-arb' and 'i2c-gate' DT subnodes
Date
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').

Signed-off-by: Peter Rosin <peda@axentia.se>
---
drivers/i2c/i2c-mux.c | 44 ++++++++++++++++++++++++++++++++++++--------
include/linux/i2c-mux.h | 8 ++++++--
2 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
index 8eee98634cda..c1ae719d1a7a 100644
--- 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 d4c1d12f900d..bd74d5706f3b 100644
--- 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)
{
--
2.1.4
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