i2c: mux: pca954x: support property idle-state
This supports property idle-state,if present, overrides i2c-mux-idle-disconnect. My use cases: - Use the property idle-state to fix an errata on LS2085ARDB and LS2088ARDB. - Errata id: E-00013(board LS2085ARDB and LS2088ARDB revision on Rev.B, Rev.C and Rev.D). - About E-00013: - Description: I2C1 and I2C3 buses are missing pull-up. - Impact: When the PCA954x device is tri-stated, the I2C bus will float. This makes the I2C bus and its associated downstream devices inaccessible. - Hardware fix: Populate resistors R189 and R190 for I2C1 and resistors R228 and R229 for I2C3. - Software fix: Remove the tri-state option from the PCA954x driver(PCA954x always on enable status, specify a channel zero in dts to fix the errata E-00013). Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com> Signed-off-by: Biwen Li <biwen.li@nxp.com> Signed-off-by: Peter Rosin <peda@axentia.se>
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@ -86,7 +86,7 @@ struct pca954x {
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u8 last_chan; /* last register value */
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u8 last_chan; /* last register value */
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/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
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/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
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s8 idle_state;
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s32 idle_state;
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struct i2c_client *client;
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struct i2c_client *client;
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@ -229,20 +229,23 @@ static int pca954x_reg_write(struct i2c_adapter *adap,
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I2C_SMBUS_BYTE, &dummy);
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I2C_SMBUS_BYTE, &dummy);
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}
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}
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static u8 pca954x_regval(struct pca954x *data, u8 chan)
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{
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/* We make switches look like muxes, not sure how to be smarter. */
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if (data->chip->muxtype == pca954x_ismux)
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return chan | data->chip->enable;
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else
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return 1 << chan;
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}
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static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
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static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
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{
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{
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struct pca954x *data = i2c_mux_priv(muxc);
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struct pca954x *data = i2c_mux_priv(muxc);
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struct i2c_client *client = data->client;
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struct i2c_client *client = data->client;
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const struct chip_desc *chip = data->chip;
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u8 regval;
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u8 regval;
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int ret = 0;
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int ret = 0;
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/* we make switches look like muxes, not sure how to be smarter */
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regval = pca954x_regval(data, chan);
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if (chip->muxtype == pca954x_ismux)
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regval = chan | chip->enable;
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else
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regval = 1 << chan;
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/* Only select the channel if its different from the last channel */
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/* Only select the channel if its different from the last channel */
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if (data->last_chan != regval) {
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if (data->last_chan != regval) {
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ret = pca954x_reg_write(muxc->parent, client, regval);
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ret = pca954x_reg_write(muxc->parent, client, regval);
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@ -256,7 +259,7 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
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{
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{
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struct pca954x *data = i2c_mux_priv(muxc);
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struct pca954x *data = i2c_mux_priv(muxc);
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struct i2c_client *client = data->client;
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struct i2c_client *client = data->client;
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s8 idle_state;
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s32 idle_state;
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idle_state = READ_ONCE(data->idle_state);
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idle_state = READ_ONCE(data->idle_state);
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if (idle_state >= 0)
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if (idle_state >= 0)
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@ -402,6 +405,22 @@ static void pca954x_cleanup(struct i2c_mux_core *muxc)
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i2c_mux_del_adapters(muxc);
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i2c_mux_del_adapters(muxc);
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}
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}
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static int pca954x_init(struct i2c_client *client, struct pca954x *data)
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{
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int ret;
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if (data->idle_state >= 0)
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data->last_chan = pca954x_regval(data, data->idle_state);
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else
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data->last_chan = 0; /* Disconnect multiplexer */
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ret = i2c_smbus_write_byte(client, data->last_chan);
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if (ret < 0)
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data->last_chan = 0;
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return ret;
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}
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/*
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/*
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* I2C init/probing/exit functions
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* I2C init/probing/exit functions
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*/
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*/
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@ -411,7 +430,6 @@ static int pca954x_probe(struct i2c_client *client,
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struct i2c_adapter *adap = client->adapter;
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struct i2c_adapter *adap = client->adapter;
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struct device *dev = &client->dev;
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struct device *dev = &client->dev;
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struct device_node *np = dev->of_node;
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struct device_node *np = dev->of_node;
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bool idle_disconnect_dt;
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struct gpio_desc *gpio;
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struct gpio_desc *gpio;
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struct i2c_mux_core *muxc;
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struct i2c_mux_core *muxc;
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struct pca954x *data;
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struct pca954x *data;
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@ -462,23 +480,24 @@ static int pca954x_probe(struct i2c_client *client,
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}
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}
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}
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}
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/* Write the mux register at addr to verify
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data->idle_state = MUX_IDLE_AS_IS;
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if (of_property_read_u32(np, "idle-state", &data->idle_state)) {
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if (np && of_property_read_bool(np, "i2c-mux-idle-disconnect"))
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data->idle_state = MUX_IDLE_DISCONNECT;
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}
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/*
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* Write the mux register at addr to verify
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* that the mux is in fact present. This also
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* that the mux is in fact present. This also
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* initializes the mux to disconnected state.
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* initializes the mux to a channel
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* or disconnected state.
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*/
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*/
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if (i2c_smbus_write_byte(client, 0) < 0) {
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ret = pca954x_init(client, data);
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if (ret < 0) {
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dev_warn(dev, "probe failed\n");
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dev_warn(dev, "probe failed\n");
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return -ENODEV;
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return -ENODEV;
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}
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}
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data->last_chan = 0; /* force the first selection */
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data->idle_state = MUX_IDLE_AS_IS;
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idle_disconnect_dt = np &&
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of_property_read_bool(np, "i2c-mux-idle-disconnect");
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if (idle_disconnect_dt)
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data->idle_state = MUX_IDLE_DISCONNECT;
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ret = pca954x_irq_setup(muxc);
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ret = pca954x_irq_setup(muxc);
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if (ret)
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if (ret)
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goto fail_cleanup;
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goto fail_cleanup;
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@ -530,9 +549,13 @@ static int pca954x_resume(struct device *dev)
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struct i2c_client *client = to_i2c_client(dev);
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struct i2c_client *client = to_i2c_client(dev);
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struct i2c_mux_core *muxc = i2c_get_clientdata(client);
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struct i2c_mux_core *muxc = i2c_get_clientdata(client);
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struct pca954x *data = i2c_mux_priv(muxc);
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struct pca954x *data = i2c_mux_priv(muxc);
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int ret;
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data->last_chan = 0;
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ret = pca954x_init(client, data);
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return i2c_smbus_write_byte(client, 0);
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if (ret < 0)
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dev_err(&client->dev, "failed to verify mux presence\n");
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return ret;
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}
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}
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#endif
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#endif
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