pwm: pca9685: Disable unused alternative addresses

The PCA9685 supports listening to 1 or more alternative I2C chip addresses
for some special features that this driver does not support.
By default the LED ALLCALL address is active (default 0x70), which causes
this chip to respond to address 0x70 in addition to its main address
(0x41). This is not desireable if there is another device on the same bus
that uses this address (like a TMP103 for example).
Since this feature is not supported by this driver, it is best to disable
these addresses in the chip to avoid unsuspected bus collisions.
Signed-off-by: David Jander <david@protonic.nl>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

drivers/pwm/pwm-pca9685.c

@@ -58,6 +58,10 @@
 #define PCA9685_MAXCHAN		0x10
 
 #define LED_FULL		BIT(4)
+#define MODE1_ALLCALL		BIT(0)
+#define MODE1_SUB3		BIT(1)
+#define MODE1_SUB2		BIT(2)
+#define MODE1_SUB1		BIT(3)
 #define MODE1_SLEEP		BIT(4)
 #define MODE2_INVRT		BIT(4)
 #define MODE2_OUTDRV		BIT(2)
@@ -443,8 +447,8 @@ static int pca9685_pwm_probe(struct i2c_client *client,
 				const struct i2c_device_id *id)
 {
 	struct pca9685 *pca;
+	unsigned int reg;
 	int ret;
-	int mode2;
 
 	pca = devm_kzalloc(&client->dev, sizeof(*pca), GFP_KERNEL);
 	if (!pca)
@@ -461,19 +465,24 @@ static int pca9685_pwm_probe(struct i2c_client *client,
 
 	i2c_set_clientdata(client, pca);
 
-	regmap_read(pca->regmap, PCA9685_MODE2, &mode2);
+	regmap_read(pca->regmap, PCA9685_MODE2, &reg);
 
 	if (device_property_read_bool(&client->dev, "invert"))
-		mode2 |= MODE2_INVRT;
+		reg |= MODE2_INVRT;
 	else
-		mode2 &= ~MODE2_INVRT;
+		reg &= ~MODE2_INVRT;
 
 	if (device_property_read_bool(&client->dev, "open-drain"))
-		mode2 &= ~MODE2_OUTDRV;
+		reg &= ~MODE2_OUTDRV;
 	else
-		mode2 |= MODE2_OUTDRV;
+		reg |= MODE2_OUTDRV;
+
+	regmap_write(pca->regmap, PCA9685_MODE2, reg);
 
-	regmap_write(pca->regmap, PCA9685_MODE2, mode2);
+	/* Disable all LED ALLCALL and SUBx addresses to avoid bus collisions */
+	regmap_read(pca->regmap, PCA9685_MODE1, &reg);
+	reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
+	regmap_write(pca->regmap, PCA9685_MODE1, reg);
 
 	/* Clear all "full off" bits */
 	regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, 0);