i2c: muxes: pca954x: Enable features on MAX7357

Enable additional features based on DT settings and unconditionally
release the shared interrupt pin after 1.6 seconds and allow to use
it as reset.

These features aren't enabled by default and it's up to board designer
to validate for proper functioning and detection of devices in secondary
bus as sometimes it can cause secondary bus being disabled.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Naresh Solanki <naresh.solanki@9elements.com>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index 2219062..f5dfc33 100644 (file)
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -57,6 +57,20 @@
 
 #define PCA954X_IRQ_OFFSET 4
 
+/*
+ * MAX7357's configuration register is writeable after POR, but
+ * can be locked by setting the basic mode bit. MAX7358 configuration
+ * register is locked by default and needs to be unlocked first.
+ * The configuration register holds the following settings:
+ */
+#define MAX7357_CONF_INT_ENABLE                        BIT(0)
+#define MAX7357_CONF_FLUSH_OUT                 BIT(1)
+#define MAX7357_CONF_RELEASE_INT               BIT(2)
+#define MAX7357_CONF_DISCON_SINGLE_CHAN                BIT(4)
+#define MAX7357_CONF_PRECONNECT_TEST           BIT(7)
+
+#define MAX7357_POR_DEFAULT_CONF               MAX7357_CONF_INT_ENABLE
+
 enum pca_type {
        max_7356,
        max_7357,
@@ -470,7 +484,34 @@ static int pca954x_init(struct i2c_client *client, struct pca954x *data)
        else
                data->last_chan = 0; /* Disconnect multiplexer */
 
-       ret = i2c_smbus_write_byte(client, data->last_chan);
+       if (device_is_compatible(&client->dev, "maxim,max7357")) {
+               if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
+                       u8 conf = MAX7357_POR_DEFAULT_CONF;
+                       /*
+                        * The interrupt signal is shared with the reset pin. Release the
+                        * interrupt after 1.6 seconds to allow using the pin as reset.
+                        */
+                       conf |= MAX7357_CONF_RELEASE_INT;
+
+                       if (device_property_read_bool(&client->dev, "maxim,isolate-stuck-channel"))
+                               conf |= MAX7357_CONF_DISCON_SINGLE_CHAN;
+                       if (device_property_read_bool(&client->dev,
+                                                     "maxim,send-flush-out-sequence"))
+                               conf |= MAX7357_CONF_FLUSH_OUT;
+                       if (device_property_read_bool(&client->dev,
+                                                     "maxim,preconnection-wiggle-test-enable"))
+                               conf |= MAX7357_CONF_PRECONNECT_TEST;
+
+                       ret = i2c_smbus_write_byte_data(client, data->last_chan, conf);
+               } else {
+                       dev_warn(&client->dev, "Write byte data not supported."
+                                "Cannot enable enhanced mode features\n");
+                       ret = i2c_smbus_write_byte(client, data->last_chan);
+               }
+       } else {
+               ret = i2c_smbus_write_byte(client, data->last_chan);
+       }
+
        if (ret < 0)
                data->last_chan = 0;