ASoC: stm32: spdifrx: add power management

Add suspend and resume sleep callbacks to STM32 SPDIFRX driver,
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_spdifrx.c

@@ -21,6 +21,7 @@
 #include <linux/delay.h>
 #include <linux/module.h>
 #include <linux/of_platform.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/regmap.h>
 #include <linux/reset.h>
 
@@ -471,6 +472,8 @@ static int stm32_spdifrx_get_ctrl_data(struct stm32_spdifrx_data *spdifrx)
 	memset(spdifrx->cs, 0, SPDIFRX_CS_BYTES_NB);
 	memset(spdifrx->ub, 0, SPDIFRX_UB_BYTES_NB);
 
+	pinctrl_pm_select_default_state(&spdifrx->pdev->dev);
+
 	ret = stm32_spdifrx_dma_ctrl_start(spdifrx);
 	if (ret < 0)
 		return ret;
@@ -502,6 +505,7 @@ static int stm32_spdifrx_get_ctrl_data(struct stm32_spdifrx_data *spdifrx)
 
 end:
 	clk_disable_unprepare(spdifrx->kclk);
+	pinctrl_pm_select_sleep_state(&spdifrx->pdev->dev);
 
 	return ret;
 }
@@ -611,10 +615,15 @@ static bool stm32_spdifrx_readable_reg(struct device *dev, unsigned int reg)
 
 static bool stm32_spdifrx_volatile_reg(struct device *dev, unsigned int reg)
 {
-	if (reg == STM32_SPDIFRX_DR)
+	switch (reg) {
+	case STM32_SPDIFRX_DR:
+	case STM32_SPDIFRX_CSR:
+	case STM32_SPDIFRX_SR:
+	case STM32_SPDIFRX_DIR:
 		return true;
-
-	return false;
+	default:
+		return false;
+	}
 }
 
 static bool stm32_spdifrx_writeable_reg(struct device *dev, unsigned int reg)
@@ -638,6 +647,7 @@ static const struct regmap_config stm32_h7_spdifrx_regmap_conf = {
 	.volatile_reg = stm32_spdifrx_volatile_reg,
 	.writeable_reg = stm32_spdifrx_writeable_reg,
 	.fast_io = true,
+	.cache_type = REGCACHE_FLAT,
 };
 
 static irqreturn_t stm32_spdifrx_isr(int irq, void *devid)
@@ -983,10 +993,36 @@ static int stm32_spdifrx_remove(struct platform_device *pdev)
 
 MODULE_DEVICE_TABLE(of, stm32_spdifrx_ids);
 
+#ifdef CONFIG_PM_SLEEP
+static int stm32_spdifrx_suspend(struct device *dev)
+{
+	struct stm32_spdifrx_data *spdifrx = dev_get_drvdata(dev);
+
+	regcache_cache_only(spdifrx->regmap, true);
+	regcache_mark_dirty(spdifrx->regmap);
+
+	return 0;
+}
+
+static int stm32_spdifrx_resume(struct device *dev)
+{
+	struct stm32_spdifrx_data *spdifrx = dev_get_drvdata(dev);
+
+	regcache_cache_only(spdifrx->regmap, false);
+
+	return regcache_sync(spdifrx->regmap);
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static const struct dev_pm_ops stm32_spdifrx_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(stm32_spdifrx_suspend, stm32_spdifrx_resume)
+};
+
 static struct platform_driver stm32_spdifrx_driver = {
 	.driver = {
 		.name = "st,stm32-spdifrx",
 		.of_match_table = stm32_spdifrx_ids,
+		.pm = &stm32_spdifrx_pm_ops,
 	},
 	.probe = stm32_spdifrx_probe,
 	.remove = stm32_spdifrx_remove,