Commit 6ef91fcca8a8 ("i2c: mux: relax locking of the top i2c adapter
during mux-locked muxing") introduced a new locking concept "mux-locked",
so that these muxes lock only the muxes on the parent adapter instead of
the whole i2c bus.
In case the dt property "mux-locked" is present make use of this
concept. This makes interaction between i2c devices behind the mux and
devices directly on the bus possible - at least in simple cases. It
might not work properly for complex i2c topologies.
If the dt property is not present use the parent-locked concept as
before.
Signed-off-by: Bastian Stender <bst@xxxxxxxxxxxxxx>
---
Changes since implicit v1 ("i2c: mux: pca954x: use relaxed locking of
the top i2c adapter during mux-locked muxing"):
- fix unlocked SMBus access
- make mux-locked optional via dt
---
drivers/i2c/muxes/i2c-mux-pca954x.c | 32 +++++++++++++++++++++++------
1 file changed, 26 insertions(+), 6 deletions(-)
diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index 09bafd3e68fa..dfa9e8d350c7 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -219,6 +219,7 @@ MODULE_DEVICE_TABLE(of, pca954x_of_match);
static int pca954x_reg_write(struct i2c_adapter *adap,
struct i2c_client *client, u8 val)
{
+ struct i2c_mux_core *muxc = i2c_get_clientdata(client);
int ret = -ENODEV;
if (adap->algo->master_xfer) {
@@ -230,16 +231,26 @@ static int pca954x_reg_write(struct i2c_adapter *adap,
msg.len = 1;
buf[0] = val;
msg.buf = buf;
- ret = __i2c_transfer(adap, &msg, 1);
+
+ if (muxc->mux_locked)
+ ret = i2c_transfer(adap, &msg, 1);
+ else
+ ret = __i2c_transfer(adap, &msg, 1);
if (ret >= 0 && ret != 1)
ret = -EREMOTEIO;
} else {
union i2c_smbus_data data;
- ret = adap->algo->smbus_xfer(adap, client->addr,
+ if (muxc->mux_locked)
+ ret = i2c_smbus_xfer(adap, client->addr,
client->flags,
I2C_SMBUS_WRITE,
val, I2C_SMBUS_BYTE, &data);
+ else
+ ret = adap->algo->smbus_xfer(adap, client->addr,
+ client->flags,
+ I2C_SMBUS_WRITE, val,
+ I2C_SMBUS_BYTE, &data);
}
return ret;
@@ -371,7 +382,9 @@ static int pca954x_probe(struct i2c_client *client,
bool idle_disconnect_dt;
struct gpio_desc *gpio;
int num, force, class;
+ bool mux_locked;
struct i2c_mux_core *muxc;
+ u32 mux_alloc_flags;
struct pca954x *data;
const struct of_device_id *match;
int ret;
@@ -379,9 +392,13 @@ static int pca954x_probe(struct i2c_client *client,
if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
return -ENODEV;
+ mux_locked = of_property_read_bool(of_node, "mux-locked");
+
+ mux_alloc_flags = mux_locked ? I2C_MUX_LOCKED : 0;
muxc = i2c_mux_alloc(adap, &client->dev,
- PCA954X_MAX_NCHANS, sizeof(*data), 0,
- pca954x_select_chan, pca954x_deselect_mux);
+ PCA954X_MAX_NCHANS, sizeof(*data),
+ mux_alloc_flags, pca954x_select_chan,
+ pca954x_deselect_mux);
if (!muxc)
return -ENOMEM;
data = i2c_mux_priv(muxc);
@@ -389,6 +406,8 @@ static int pca954x_probe(struct i2c_client *client,
i2c_set_clientdata(client, muxc);
data->client = client;
+ muxc->mux_locked = mux_locked;
+
/* Get the mux out of reset if a reset GPIO is specified. */
gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_LOW);
if (IS_ERR(gpio))
@@ -470,8 +489,9 @@ static int pca954x_probe(struct i2c_client *client,
}
dev_info(&client->dev,
- "registered %d multiplexed busses for I2C %s %s\n",
- num, data->chip->muxtype == pca954x_ismux
+ "registered %d multiplexed busses for %s-locked I2C %s %s\n",
+ num, muxc->mux_locked ? "mux" : "parent",
+ data->chip->muxtype == pca954x_ismux
? "mux" : "switch", client->name);
return 0;
--
2.17.0
