staging:iio:hmc5843: Check initialization and chip identifier

Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/staging/iio/magnetometer/hmc5843.c

@@ -33,6 +33,7 @@
 #define HMC5843_MODE_REG			0x02
 #define HMC5843_DATA_OUT_MSB_REGS		0x03
 #define HMC5843_STATUS_REG			0x09
+#define HMC5843_ID_REG				0x0a
 
 enum hmc5843_ids {
 	HMC5843_ID,
@@ -497,12 +498,30 @@ static const struct hmc5843_chip_info hmc5843_chip_info_tbl[] = {
 	},
 };
 
-static void hmc5843_init(struct hmc5843_data *data)
+static int hmc5843_init(struct hmc5843_data *data)
 {
-	hmc5843_set_meas_conf(data, HMC5843_MEAS_CONF_NORMAL);
-	hmc5843_set_samp_freq(data, HMC5843_RATE_DEFAULT);
-	hmc5843_set_range_gain(data, HMC5843_RANGE_GAIN_DEFAULT);
-	hmc5843_set_mode(data, HMC5843_MODE_CONVERSION_CONTINUOUS);
+	int ret;
+	u8 id[3];
+
+	ret = i2c_smbus_read_i2c_block_data(data->client, HMC5843_ID_REG,
+		sizeof(id), id);
+	if (ret < 0)
+		return ret;
+	if (id[0] != 'H' || id[1] != '4' || id[2] != '3') {
+		dev_err(&data->client->dev, "no HMC5843/5883/5883L sensor\n");
+		return -ENODEV;
+	}
+
+	ret = hmc5843_set_meas_conf(data, HMC5843_MEAS_CONF_NORMAL);
+	if (ret < 0)
+		return ret;
+	ret = hmc5843_set_samp_freq(data, HMC5843_RATE_DEFAULT);
+	if (ret < 0)
+		return ret;
+	ret = hmc5843_set_range_gain(data, HMC5843_RANGE_GAIN_DEFAULT);
+	if (ret < 0)
+		return ret;
+	return hmc5843_set_mode(data, HMC5843_MODE_CONVERSION_CONTINUOUS);
 }
 
 static const struct iio_info hmc5843_info = {
@@ -541,7 +560,9 @@ static int hmc5843_probe(struct i2c_client *client,
 	indio_dev->num_channels = 4;
 	indio_dev->available_scan_masks = hmc5843_scan_masks;
 
-	hmc5843_init(data);
+	ret = hmc5843_init(data);
+	if (ret < 0)
+		return ret;
 
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
 		hmc5843_trigger_handler, NULL);