+#ifdef CONFIG_PM
+
+/* This suspend/resume implementation can handle both - a simple standby
+ * where the codec remains powered, and a full suspend, where the voltage
+ * domain the codec is connected to is teared down and/or any other hardware
+ * reset condition is asserted.
+ *
+ * The codec's own power saving features are enabled in the suspend callback,
+ * and all registers are written back to the hardware when resuming.
+ */
+
+static int cs4270_soc_suspend(struct platform_device *pdev, pm_message_t mesg)
+{
+ struct snd_soc_codec *codec = cs4270_codec;
+ struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
+ int reg, ret;
+
+ reg = snd_soc_read(codec, CS4270_PWRCTL) | CS4270_PWRCTL_PDN_ALL;
+ if (reg < 0)
+ return reg;
+
+ ret = snd_soc_write(codec, CS4270_PWRCTL, reg);
+ if (ret < 0)
+ return ret;
+
+ regulator_bulk_disable(ARRAY_SIZE(cs4270->supplies),
+ cs4270->supplies);
+
+ return 0;
+}
+
+static int cs4270_soc_resume(struct platform_device *pdev)
+{
+ struct snd_soc_codec *codec = cs4270_codec;
+ struct cs4270_private *cs4270 = snd_soc_codec_get_drvdata(codec);
+ struct i2c_client *i2c_client = codec->control_data;
+ int reg;
+
+ regulator_bulk_enable(ARRAY_SIZE(cs4270->supplies),
+ cs4270->supplies);
+
+ /* In case the device was put to hard reset during sleep, we need to
+ * wait 500ns here before any I2C communication. */
+ ndelay(500);
+
+ /* first restore the entire register cache ... */
+ for (reg = CS4270_FIRSTREG; reg <= CS4270_LASTREG; reg++) {
+ u8 val = snd_soc_read(codec, reg);
+
+ if (i2c_smbus_write_byte_data(i2c_client, reg, val)) {
+ dev_err(codec->dev, "i2c write failed\n");
+ return -EIO;
+ }
+ }
+
+ /* ... then disable the power-down bits */
+ reg = snd_soc_read(codec, CS4270_PWRCTL);
+ reg &= ~CS4270_PWRCTL_PDN_ALL;
+
+ return snd_soc_write(codec, CS4270_PWRCTL, reg);
+}
+#else
+#define cs4270_soc_suspend NULL
+#define cs4270_soc_resume NULL
+#endif /* CONFIG_PM */
+