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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>
This commit is contained in:
Biwen Li 2019-12-25 18:36:23 +08:00 committed by Peter Rosin
parent 0d1569a763
commit e65e228eb0
1 changed files with 46 additions and 23 deletions
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69
drivers/i2c/muxes/i2c-mux-pca954x.c
View File

@ -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