Commit e65e228e authored by Biwen Li's avatar Biwen Li Committed by Peter Rosin
Browse files

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: default avatarIoana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: default avatarBiwen Li <biwen.li@nxp.com>
Signed-off-by: default avatarPeter Rosin <peda@axentia.se>
parent 0d1569a7

drivers/i2c/muxes/i2c-mux-pca954x.c

+46 −23
Original line number Diff line number Diff line
@@ -86,7 +86,7 @@ struct pca954x { 


	u8 last_chan;		/* last register value */

	/* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */

	s8 idle_state;

	s32 idle_state;



	struct i2c_client *client;
@@ -229,20 +229,23 @@ static int pca954x_reg_write(struct i2c_adapter *adap, 
				I2C_SMBUS_BYTE, &dummy);

}



static u8 pca954x_regval(struct pca954x *data, u8 chan)

{

	/* We make switches look like muxes, not sure how to be smarter. */

	if (data->chip->muxtype == pca954x_ismux)

		return chan | data->chip->enable;

	else

		return 1 << chan;

}



static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)

{

	struct pca954x *data = i2c_mux_priv(muxc);

	struct i2c_client *client = data->client;

	const struct chip_desc *chip = data->chip;

	u8 regval;

	int ret = 0;



	/* we make switches look like muxes, not sure how to be smarter */

	if (chip->muxtype == pca954x_ismux)

		regval = chan | chip->enable;

	else

		regval = 1 << chan;



	regval = pca954x_regval(data, chan);

	/* Only select the channel if its different from the last channel */

	if (data->last_chan != regval) {

		ret = pca954x_reg_write(muxc->parent, client, regval);
@@ -256,7 +259,7 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan) 
{

	struct pca954x *data = i2c_mux_priv(muxc);

	struct i2c_client *client = data->client;

	s8 idle_state;

	s32 idle_state;



	idle_state = READ_ONCE(data->idle_state);

	if (idle_state >= 0)
@@ -402,6 +405,22 @@ static void pca954x_cleanup(struct i2c_mux_core *muxc) 
	i2c_mux_del_adapters(muxc);

}



static int pca954x_init(struct i2c_client *client, struct pca954x *data)

{

	int ret;



	if (data->idle_state >= 0)

		data->last_chan = pca954x_regval(data, data->idle_state);

	else

		data->last_chan = 0; /* Disconnect multiplexer */



	ret = i2c_smbus_write_byte(client, data->last_chan);

	if (ret < 0)

		data->last_chan = 0;



	return ret;

}



/*

 * I2C init/probing/exit functions

 */
@@ -411,7 +430,6 @@ static int pca954x_probe(struct i2c_client *client, 
	struct i2c_adapter *adap = client->adapter;

	struct device *dev = &client->dev;

	struct device_node *np = dev->of_node;

	bool idle_disconnect_dt;

	struct gpio_desc *gpio;

	struct i2c_mux_core *muxc;

	struct pca954x *data;
@@ -462,23 +480,24 @@ static int pca954x_probe(struct i2c_client *client, 
		}

	}



	/* Write the mux register at addr to verify

	data->idle_state = MUX_IDLE_AS_IS;

	if (of_property_read_u32(np, "idle-state", &data->idle_state)) {

		if (np && of_property_read_bool(np, "i2c-mux-idle-disconnect"))

			data->idle_state = MUX_IDLE_DISCONNECT;

	}



	/*

	 * Write the mux register at addr to verify

	 * that the mux is in fact present. This also

	 * initializes the mux to disconnected state.

	 * initializes the mux to a channel

	 * or disconnected state.

	 */

	if (i2c_smbus_write_byte(client, 0) < 0) {

	ret = pca954x_init(client, data);

	if (ret < 0) {

		dev_warn(dev, "probe failed\n");

		return -ENODEV;

	}



	data->last_chan = 0;		   /* force the first selection */

	data->idle_state = MUX_IDLE_AS_IS;



	idle_disconnect_dt = np &&

		of_property_read_bool(np, "i2c-mux-idle-disconnect");

	if (idle_disconnect_dt)

		data->idle_state = MUX_IDLE_DISCONNECT;



	ret = pca954x_irq_setup(muxc);

	if (ret)

		goto fail_cleanup;
@@ -530,9 +549,13 @@ static int pca954x_resume(struct device *dev) 
	struct i2c_client *client = to_i2c_client(dev);

	struct i2c_mux_core *muxc = i2c_get_clientdata(client);

	struct pca954x *data = i2c_mux_priv(muxc);

	int ret;



	data->last_chan = 0;

	return i2c_smbus_write_byte(client, 0);

	ret = pca954x_init(client, data);

	if (ret < 0)

		dev_err(&client->dev, "failed to verify mux presence\n");



	return ret;

}

#endif

CRA Git | Maintained and supported by SUSTech CRA and CCSE