+#ifdef CONFIG_PM
+static int mlx90614_sleep(struct mlx90614_data *data)
+{
+ s32 ret;
+
+ if (!data->wakeup_gpio) {
+ dev_dbg(&data->client->dev, "Sleep disabled");
+ return -ENOSYS;
+ }
+
+ dev_dbg(&data->client->dev, "Requesting sleep");
+
+ mutex_lock(&data->lock);
+ ret = i2c_smbus_xfer(data->client->adapter, data->client->addr,
+ data->client->flags | I2C_CLIENT_PEC,
+ I2C_SMBUS_WRITE, MLX90614_OP_SLEEP,
+ I2C_SMBUS_BYTE, NULL);
+ mutex_unlock(&data->lock);
+
+ return ret;
+}
+
+static int mlx90614_wakeup(struct mlx90614_data *data)
+{
+ if (!data->wakeup_gpio) {
+ dev_dbg(&data->client->dev, "Wake-up disabled");
+ return -ENOSYS;
+ }
+
+ dev_dbg(&data->client->dev, "Requesting wake-up");
+
+ i2c_lock_adapter(data->client->adapter);
+ gpiod_direction_output(data->wakeup_gpio, 0);
+ msleep(MLX90614_TIMING_WAKEUP);
+ gpiod_direction_input(data->wakeup_gpio);
+ i2c_unlock_adapter(data->client->adapter);
+
+ data->ready_timestamp = jiffies +
+ msecs_to_jiffies(MLX90614_TIMING_STARTUP);
+
+ /*
+ * Quirk: the i2c controller may get confused right after the
+ * wake-up signal has been sent. As a workaround, do a dummy read.
+ * If the read fails, the controller will probably be reset so that
+ * further reads will work.
+ */
+ i2c_smbus_read_word_data(data->client, MLX90614_CONFIG);
+
+ return 0;
+}
+
+/* Return wake-up GPIO or NULL if sleep functionality should be disabled. */
+static struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
+{
+ struct gpio_desc *gpio;
+
+ if (!i2c_check_functionality(client->adapter,
+ I2C_FUNC_SMBUS_WRITE_BYTE)) {
+ dev_info(&client->dev,
+ "i2c adapter does not support SMBUS_WRITE_BYTE, sleep disabled");
+ return NULL;
+ }
+
+ gpio = devm_gpiod_get_optional(&client->dev, "wakeup", GPIOD_IN);
+
+ if (IS_ERR(gpio)) {
+ dev_warn(&client->dev,
+ "gpio acquisition failed with error %ld, sleep disabled",
+ PTR_ERR(gpio));
+ return NULL;
+ } else if (!gpio) {
+ dev_info(&client->dev,
+ "wakeup-gpio not found, sleep disabled");
+ }
+
+ return gpio;
+}
+#else
+static inline int mlx90614_sleep(struct mlx90614_data *data)
+{
+ return -ENOSYS;
+}
+static inline int mlx90614_wakeup(struct mlx90614_data *data)
+{
+ return -ENOSYS;
+}
+static inline struct gpio_desc *mlx90614_probe_wakeup(struct i2c_client *client)
+{
+ return NULL;
+}
+#endif
+