iio: accel: bmc150: Check for a second ACPI device for BOSC0200

Some BOSC0200 acpi_device-s describe two accelerometers in a single ACPI
device. Normally we would handle this by letting the special
drivers/platform/x86/i2c-multi-instantiate.c driver handle the BOSC0200
ACPI id and let it instantiate 2 bmc150_accel type i2c_client-s for us.

But doing so changes the modalias for the first accelerometer
(which is already supported and used on many devices) from
acpi:BOSC0200 to i2c:bmc150_accel. The modalias is not only used
to load the driver, but is also used by hwdb matches in
/lib/udev/hwdb.d/60-sensor.hwdb which provide a mountmatrix to
userspace by setting the ACCEL_MOUNT_MATRIX udev property.

Switching the handling of the BOSC0200 over to i2c-multi-instantiate.c
will break the hwdb matches causing the ACCEL_MOUNT_MATRIX udev prop
to no longer be set. So switching over to i2c-multi-instantiate.c is
not an option.

Changes by Hans de Goede:
-Add explanation to the commit message why i2c-multi-instantiate.c
 cannot be used
-Also set the dev_name, fwnode and irq i2c_board_info struct members
 for the 2nd client

Signed-off-by: Jeremy Cline <jeremy@jcline.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20201130141954.339805-2-hdegoede@redhat.com
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=198671
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/bmc150-accel-core.c

@@ -206,6 +206,7 @@ struct bmc150_accel_data {
 	int ev_enable_state;
 	int64_t timestamp, old_timestamp; /* Only used in hw fifo mode. */
 	const struct bmc150_accel_chip_info *chip_info;
+	struct i2c_client *second_device;
 	struct iio_mount_matrix orientation;
 };
 
@@ -1701,6 +1702,26 @@ err_disable_regulators:
 }
 EXPORT_SYMBOL_GPL(bmc150_accel_core_probe);
 
+struct i2c_client *bmc150_get_second_device(struct i2c_client *client)
+{
+	struct bmc150_accel_data *data = i2c_get_clientdata(client);
+
+	if (!data)
+		return NULL;
+
+	return data->second_device;
+}
+EXPORT_SYMBOL_GPL(bmc150_get_second_device);
+
+void bmc150_set_second_device(struct i2c_client *client)
+{
+	struct bmc150_accel_data *data = i2c_get_clientdata(client);
+
+	if (data)
+		data->second_device = client;
+}
+EXPORT_SYMBOL_GPL(bmc150_set_second_device);
+
 int bmc150_accel_core_remove(struct device *dev)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);

drivers/iio/accel/bmc150-accel-i2c.c

@@ -30,6 +30,8 @@ static int bmc150_accel_probe(struct i2c_client *client,
 		i2c_check_functionality(client->adapter, I2C_FUNC_I2C) ||
 		i2c_check_functionality(client->adapter,
 					I2C_FUNC_SMBUS_READ_I2C_BLOCK);
+	struct acpi_device __maybe_unused *adev;
+	int ret;
 
 	regmap = devm_regmap_init_i2c(client, &bmc150_regmap_conf);
 	if (IS_ERR(regmap)) {
@@ -40,12 +42,47 @@ static int bmc150_accel_probe(struct i2c_client *client,
 	if (id)
 		name = id->name;
 
-	return bmc150_accel_core_probe(&client->dev, regmap, client->irq, name,
-				       block_supported);
+	ret = bmc150_accel_core_probe(&client->dev, regmap, client->irq, name, block_supported);
+	if (ret)
+		return ret;
+
+	/*
+	 * Some BOSC0200 acpi_devices describe 2 accelerometers in a single ACPI
+	 * device, try instantiating a second i2c_client for an I2cSerialBusV2
+	 * ACPI resource with index 1. The !id check avoids recursion when
+	 * bmc150_accel_probe() gets called for the second client.
+	 */
+#ifdef CONFIG_ACPI
+	adev = ACPI_COMPANION(&client->dev);
+	if (!id && adev && strcmp(acpi_device_hid(adev), "BOSC0200") == 0) {
+		struct i2c_board_info board_info = {
+			.type = "bmc150_accel",
+			/*
+			 * The 2nd accel sits in the base of 2-in-1s. Note this
+			 * name is static, as there should never be more then 1
+			 * BOSC0200 ACPI node with 2 accelerometers in it.
+			 */
+			.dev_name = "BOSC0200:base",
+			.fwnode = client->dev.fwnode,
+			.irq = -ENOENT,
+		};
+		struct i2c_client *second_dev;
+
+		second_dev = i2c_acpi_new_device(&client->dev, 1, &board_info);
+		if (!IS_ERR(second_dev))
+			bmc150_set_second_device(second_dev);
+	}
+#endif
+
+	return 0;
 }
 
 static int bmc150_accel_remove(struct i2c_client *client)
 {
+	struct i2c_client *second_dev = bmc150_get_second_device(client);
+
+	i2c_unregister_device(second_dev);
+
 	return bmc150_accel_core_remove(&client->dev);
 }
 

drivers/iio/accel/bmc150-accel.h

@@ -17,6 +17,8 @@ enum {
 int bmc150_accel_core_probe(struct device *dev, struct regmap *regmap, int irq,
 			    const char *name, bool block_supported);
 int bmc150_accel_core_remove(struct device *dev);
+struct i2c_client *bmc150_get_second_device(struct i2c_client *second_device);
+void bmc150_set_second_device(struct i2c_client *second_device);
 extern const struct dev_pm_ops bmc150_accel_pm_ops;
 extern const struct regmap_config bmc150_regmap_conf;