From: Priyanka Jain <priyanka.j...@freescale.com>
On some Layerscape boards like LS2085ARDB/LS2080ARDB,
input pull-up resistors on PCA954x Mux device are
missing on board. So, if mux are disabled after powered-on,
input lines will float leading to incorrect functionality.
Hence, PCA954x Mux device should never be turned-off after
power-on.
Add option to skip disabling PCA954x Mux device
if device tree contians "i2c-mux-never-disable" property
for pca954x device node.
Signed-off-by: Zhang Ying-22455 <ying.zhang22...@nxp.com>
---
drivers/i2c/muxes/i2c-mux-pca954x.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c
b/drivers/i2c/muxes/i2c-mux-pca954x.c
index f1751c2..4d18fc0 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -85,6 +85,7 @@ struct pca954x {
struct irq_domain *irq;
unsigned int irq_mask;
raw_spinlock_t lock;
+ u8 disable_mux; /* do not disable mux if val not 0 */
};
/* Provide specs for the PCA954x types we know about */
@@ -221,6 +222,13 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc,
u32 chan)
if (!(data->deselect & (1 << chan)))
return 0;
+#ifdef CONFIG_ARCH_LAYERSCAPE
+ if (data->disable_mux != 0)
+ data->last_chan = data->chip->nchans;
+ else
+ data->last_chan = 0;
+ return pca954x_reg_write(muxc->parent, client, data->disable_mux);
+#endif
/* Deselect active channel */
data->last_chan = 0;
return pca954x_reg_write(muxc->parent, client, data->last_chan);
@@ -361,6 +369,22 @@ static int pca954x_probe(struct i2c_client *client,
return -ENOMEM;
data = i2c_mux_priv(muxc);
+#ifdef CONFIG_ARCH_LAYERSCAPE
+ /* The point here is that you must not disable a mux if there
+ * are no pullups on the input or you mess up the I2C. This
+ * needs to be put into the DTS really as the kernel cannot
+ * know this otherwise.
+ */
+ data->disable_mux = of_node &&
+ of_property_read_bool(of_node, "i2c-mux-never-disable") &&
+ data->chip->muxtype == pca954x_ismux ?
+ data->chip->enable : 0;
+ /* force the first selection */
+ if (data->disable_mux != 0)
+ data->last_chan = data->chip->nchans;
+ else
+ data->last_chan = 0;
+#endif
i2c_set_clientdata(client, muxc);
data->client = client;
@@ -373,7 +397,11 @@ static int pca954x_probe(struct i2c_client *client,
* that the mux is in fact present. This also
* initializes the mux to disconnected state.
*/
+#ifdef CONFIG_ARCH_LAYERSCAPE
+ if (i2c_smbus_write_byte(client, data->disable_mux) < 0) {
+#else
if (i2c_smbus_write_byte(client, 0) < 0) {
+#endif
dev_warn(&client->dev, "probe failed\n");
return -ENODEV;
}
@@ -384,7 +412,9 @@ static int pca954x_probe(struct i2c_client *client,
else
data->chip = &chips[id->driver_data];
+#ifndef CONFIG_ARCH_LAYERSCAPE
data->last_chan = 0; /* force the first selection */
+#endif
idle_disconnect_dt = of_node &&
of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
@@ -454,6 +484,13 @@ static int pca954x_resume(struct device *dev)
struct i2c_mux_core *muxc = i2c_get_clientdata(client);
struct pca954x *data = i2c_mux_priv(muxc);
+#ifdef CONFIG_ARCH_LAYERSCAPE
+ if (data->disable_mux != 0)
+ data->last_chan = data->chip->nchans;
+ else
+ data->last_chan = 0;
+ return i2c_smbus_write_byte(client, data->disable_mux);
+#endif
data->last_chan = 0;
return i2c_smbus_write_byte(client, 0);
}
--
2.1.0.27.g96db324
