ASoC: stm32: i2s: add power management

Add suspend and resume sleep callbacks,
to support system low power modes.
Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/stm/stm32_i2s.c

@@ -186,8 +186,9 @@ enum i2s_datlen {
 #define STM32_I2S_IS_SLAVE(x)		((x)->ms_flg == I2S_MS_SLAVE)
 
 /**
+ * struct stm32_i2s_data - private data of I2S
  * @regmap_conf: I2S register map configuration pointer
- * @egmap: I2S register map pointer
+ * @regmap: I2S register map pointer
  * @pdev: device data pointer
  * @dai_drv: DAI driver pointer
  * @dma_data_tx: dma configuration data for tx channel
@@ -596,7 +597,7 @@ static int stm32_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
 			return ret;
 		}
 
-		ret = regmap_update_bits(i2s->regmap, STM32_I2S_CR1_REG,
+		ret = regmap_write_bits(i2s->regmap, STM32_I2S_CR1_REG,
 					I2S_CR1_CSTART, I2S_CR1_CSTART);
 		if (ret < 0) {
 			dev_err(cpu_dai->dev, "Error %d starting I2S\n", ret);
@@ -703,6 +704,7 @@ static const struct regmap_config stm32_h7_i2s_regmap_conf = {
 	.volatile_reg = stm32_i2s_volatile_reg,
 	.writeable_reg = stm32_i2s_writeable_reg,
 	.fast_io = true,
+	.cache_type = REGCACHE_FLAT,
 };
 
 static const struct snd_soc_dai_ops stm32_i2s_pcm_dai_ops = {
@@ -929,10 +931,35 @@ static int stm32_i2s_remove(struct platform_device *pdev)
 
 MODULE_DEVICE_TABLE(of, stm32_i2s_ids);
 
+#ifdef CONFIG_PM_SLEEP
+static int stm32_i2s_suspend(struct device *dev)
+{
+	struct stm32_i2s_data *i2s = dev_get_drvdata(dev);
+
+	regcache_cache_only(i2s->regmap, true);
+	regcache_mark_dirty(i2s->regmap);
+
+	return 0;
+}
+
+static int stm32_i2s_resume(struct device *dev)
+{
+	struct stm32_i2s_data *i2s = dev_get_drvdata(dev);
+
+	regcache_cache_only(i2s->regmap, false);
+	return regcache_sync(i2s->regmap);
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct dev_pm_ops stm32_i2s_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(stm32_i2s_suspend, stm32_i2s_resume)
+};
+
 static struct platform_driver stm32_i2s_driver = {
 	.driver = {
 		.name = "st,stm32-i2s",
 		.of_match_table = stm32_i2s_ids,
+		.pm = &stm32_i2s_pm_ops,
 	},
 	.probe = stm32_i2s_probe,
 	.remove = stm32_i2s_remove,