iio: adc: stm32-dfsdm: add PM support

Add PM and runtime PM support to STM32 DFSDM drivers:
- stm32-dfsdm-core: manage clocks.
- stm32-dfsdm-adc: restore channels configuration upon resume. Also stop
  restart everything in case of buffer mode.
Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/stm32-dfsdm-adc.c

@@ -868,24 +868,18 @@ static int stm32_dfsdm_update_scan_mode(struct iio_dev *indio_dev,
 	return 0;
 }
 
-static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
+static int __stm32_dfsdm_postenable(struct iio_dev *indio_dev)
 {
 	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
 	int ret;
 
-	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
-		ret = iio_triggered_buffer_postenable(indio_dev);
-		if (ret < 0)
-			return ret;
-	}
-
 	/* Reset adc buffer index */
 	adc->bufi = 0;
 
 	if (adc->hwc) {
 		ret = iio_hw_consumer_enable(adc->hwc);
 		if (ret < 0)
-			goto err_predisable;
+			return ret;
 	}
 
 	ret = stm32_dfsdm_start_dfsdm(adc->dfsdm);
@@ -913,6 +907,26 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
 err_stop_hwc:
 	if (adc->hwc)
 		iio_hw_consumer_disable(adc->hwc);
+
+	return ret;
+}
+
+static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
+{
+	int ret;
+
+	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
+		ret = iio_triggered_buffer_postenable(indio_dev);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = __stm32_dfsdm_postenable(indio_dev);
+	if (ret < 0)
+		goto err_predisable;
+
+	return 0;
+
 err_predisable:
 	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED)
 		iio_triggered_buffer_predisable(indio_dev);
@@ -920,7 +934,7 @@ static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
 	return ret;
 }
 
-static int stm32_dfsdm_predisable(struct iio_dev *indio_dev)
+static void __stm32_dfsdm_predisable(struct iio_dev *indio_dev)
 {
 	struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
 
@@ -932,6 +946,11 @@ static int stm32_dfsdm_predisable(struct iio_dev *indio_dev)
 
 	if (adc->hwc)
 		iio_hw_consumer_disable(adc->hwc);
+}
+
+static int stm32_dfsdm_predisable(struct iio_dev *indio_dev)
+{
+	__stm32_dfsdm_predisable(indio_dev);
 
 	if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED)
 		iio_triggered_buffer_predisable(indio_dev);
@@ -1496,10 +1515,48 @@ static int stm32_dfsdm_adc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int __maybe_unused stm32_dfsdm_adc_suspend(struct device *dev)
+{
+	struct stm32_dfsdm_adc *adc = dev_get_drvdata(dev);
+	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+
+	if (iio_buffer_enabled(indio_dev))
+		__stm32_dfsdm_predisable(indio_dev);
+
+	return 0;
+}
+
+static int __maybe_unused stm32_dfsdm_adc_resume(struct device *dev)
+{
+	struct stm32_dfsdm_adc *adc = dev_get_drvdata(dev);
+	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	const struct iio_chan_spec *chan;
+	struct stm32_dfsdm_channel *ch;
+	int i, ret;
+
+	/* restore channels configuration */
+	for (i = 0; i < indio_dev->num_channels; i++) {
+		chan = indio_dev->channels + i;
+		ch = &adc->dfsdm->ch_list[chan->channel];
+		ret = stm32_dfsdm_chan_configure(adc->dfsdm, ch);
+		if (ret)
+			return ret;
+	}
+
+	if (iio_buffer_enabled(indio_dev))
+		__stm32_dfsdm_postenable(indio_dev);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(stm32_dfsdm_adc_pm_ops,
+			 stm32_dfsdm_adc_suspend, stm32_dfsdm_adc_resume);
+
 static struct platform_driver stm32_dfsdm_adc_driver = {
 	.driver = {
 		.name = "stm32-dfsdm-adc",
 		.of_match_table = stm32_dfsdm_adc_match,
+		.pm = &stm32_dfsdm_adc_pm_ops,
 	},
 	.probe = stm32_dfsdm_adc_probe,
 	.remove = stm32_dfsdm_adc_remove,

drivers/iio/adc/stm32-dfsdm-core.c

@@ -12,6 +12,8 @@
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 
@@ -90,6 +92,36 @@ struct dfsdm_priv {
 	struct clk *aclk; /* audio clock */
 };
 
+static inline struct dfsdm_priv *to_stm32_dfsdm_priv(struct stm32_dfsdm *dfsdm)
+{
+	return container_of(dfsdm, struct dfsdm_priv, dfsdm);
+}
+
+static int stm32_dfsdm_clk_prepare_enable(struct stm32_dfsdm *dfsdm)
+{
+	struct dfsdm_priv *priv = to_stm32_dfsdm_priv(dfsdm);
+	int ret;
+
+	ret = clk_prepare_enable(priv->clk);
+	if (ret || !priv->aclk)
+		return ret;
+
+	ret = clk_prepare_enable(priv->aclk);
+	if (ret)
+		clk_disable_unprepare(priv->clk);
+
+	return ret;
+}
+
+static void stm32_dfsdm_clk_disable_unprepare(struct stm32_dfsdm *dfsdm)
+{
+	struct dfsdm_priv *priv = to_stm32_dfsdm_priv(dfsdm);
+
+	if (priv->aclk)
+		clk_disable_unprepare(priv->aclk);
+	clk_disable_unprepare(priv->clk);
+}
+
 /**
  * stm32_dfsdm_start_dfsdm - start global dfsdm interface.
  *
@@ -98,24 +130,17 @@ struct dfsdm_priv {
  */
 int stm32_dfsdm_start_dfsdm(struct stm32_dfsdm *dfsdm)
 {
-	struct dfsdm_priv *priv = container_of(dfsdm, struct dfsdm_priv, dfsdm);
+	struct dfsdm_priv *priv = to_stm32_dfsdm_priv(dfsdm);
 	struct device *dev = &priv->pdev->dev;
 	unsigned int clk_div = priv->spi_clk_out_div, clk_src;
 	int ret;
 
 	if (atomic_inc_return(&priv->n_active_ch) == 1) {
-		ret = clk_prepare_enable(priv->clk);
+		ret = pm_runtime_get_sync(dev);
 		if (ret < 0) {
-			dev_err(dev, "Failed to start clock\n");
+			pm_runtime_put_noidle(dev);
 			goto error_ret;
 		}
-		if (priv->aclk) {
-			ret = clk_prepare_enable(priv->aclk);
-			if (ret < 0) {
-				dev_err(dev, "Failed to start audio clock\n");
-				goto disable_clk;
-			}
-		}
 
 		/* select clock source, e.g. 0 for "dfsdm" or 1 for "audio" */
 		clk_src = priv->aclk ? 1 : 0;
@@ -123,21 +148,21 @@ int stm32_dfsdm_start_dfsdm(struct stm32_dfsdm *dfsdm)
 					 DFSDM_CHCFGR1_CKOUTSRC_MASK,
 					 DFSDM_CHCFGR1_CKOUTSRC(clk_src));
 		if (ret < 0)
-			goto disable_aclk;
+			goto pm_put;
 
 		/* Output the SPI CLKOUT (if clk_div == 0 clock if OFF) */
 		ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
 					 DFSDM_CHCFGR1_CKOUTDIV_MASK,
 					 DFSDM_CHCFGR1_CKOUTDIV(clk_div));
 		if (ret < 0)
-			goto disable_aclk;
+			goto pm_put;
 
 		/* Global enable of DFSDM interface */
 		ret = regmap_update_bits(dfsdm->regmap, DFSDM_CHCFGR1(0),
 					 DFSDM_CHCFGR1_DFSDMEN_MASK,
 					 DFSDM_CHCFGR1_DFSDMEN(1));
 		if (ret < 0)
-			goto disable_aclk;
+			goto pm_put;
 	}
 
 	dev_dbg(dev, "%s: n_active_ch %d\n", __func__,
@@ -145,11 +170,8 @@ int stm32_dfsdm_start_dfsdm(struct stm32_dfsdm *dfsdm)
 
 	return 0;
 
-disable_aclk:
-	clk_disable_unprepare(priv->aclk);
-disable_clk:
-	clk_disable_unprepare(priv->clk);
-
+pm_put:
+	pm_runtime_put_sync(dev);
 error_ret:
 	atomic_dec(&priv->n_active_ch);
 
@@ -165,7 +187,7 @@ EXPORT_SYMBOL_GPL(stm32_dfsdm_start_dfsdm);
  */
 int stm32_dfsdm_stop_dfsdm(struct stm32_dfsdm *dfsdm)
 {
-	struct dfsdm_priv *priv = container_of(dfsdm, struct dfsdm_priv, dfsdm);
+	struct dfsdm_priv *priv = to_stm32_dfsdm_priv(dfsdm);
 	int ret;
 
 	if (atomic_dec_and_test(&priv->n_active_ch)) {
@@ -183,9 +205,7 @@ int stm32_dfsdm_stop_dfsdm(struct stm32_dfsdm *dfsdm)
 		if (ret < 0)
 			return ret;
 
-		clk_disable_unprepare(priv->clk);
-		if (priv->aclk)
-			clk_disable_unprepare(priv->aclk);
+		pm_runtime_put_sync(&priv->pdev->dev);
 	}
 	dev_dbg(&priv->pdev->dev, "%s: n_active_ch %d\n", __func__,
 		atomic_read(&priv->n_active_ch));
@@ -325,14 +345,111 @@ static int stm32_dfsdm_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, dfsdm);
 
-	return devm_of_platform_populate(&pdev->dev);
+	ret = stm32_dfsdm_clk_prepare_enable(dfsdm);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to start clock\n");
+		return ret;
+	}
+
+	pm_runtime_get_noresume(&pdev->dev);
+	pm_runtime_set_active(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
+	ret = of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
+	if (ret)
+		goto pm_put;
+
+	pm_runtime_put(&pdev->dev);
+
+	return 0;
+
+pm_put:
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+	stm32_dfsdm_clk_disable_unprepare(dfsdm);
+
+	return ret;
+}
+
+static int stm32_dfsdm_core_remove(struct platform_device *pdev)
+{
+	struct stm32_dfsdm *dfsdm = platform_get_drvdata(pdev);
+
+	pm_runtime_get_sync(&pdev->dev);
+	of_platform_depopulate(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
+	pm_runtime_put_noidle(&pdev->dev);
+	stm32_dfsdm_clk_disable_unprepare(dfsdm);
+
+	return 0;
+}
+
+static int __maybe_unused stm32_dfsdm_core_suspend(struct device *dev)
+{
+	struct stm32_dfsdm *dfsdm = dev_get_drvdata(dev);
+	struct dfsdm_priv *priv = to_stm32_dfsdm_priv(dfsdm);
+	int ret;
+
+	ret = pm_runtime_force_suspend(dev);
+	if (ret)
+		return ret;
+
+	/* Balance devm_regmap_init_mmio_clk() clk_prepare() */
+	clk_unprepare(priv->clk);
+
+	return pinctrl_pm_select_sleep_state(dev);
+}
+
+static int __maybe_unused stm32_dfsdm_core_resume(struct device *dev)
+{
+	struct stm32_dfsdm *dfsdm = dev_get_drvdata(dev);
+	struct dfsdm_priv *priv = to_stm32_dfsdm_priv(dfsdm);
+	int ret;
+
+	ret = pinctrl_pm_select_default_state(dev);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare(priv->clk);
+	if (ret)
+		return ret;
+
+	return pm_runtime_force_resume(dev);
 }
 
+static int __maybe_unused stm32_dfsdm_core_runtime_suspend(struct device *dev)
+{
+	struct stm32_dfsdm *dfsdm = dev_get_drvdata(dev);
+
+	stm32_dfsdm_clk_disable_unprepare(dfsdm);
+
+	return 0;
+}
+
+static int __maybe_unused stm32_dfsdm_core_runtime_resume(struct device *dev)
+{
+	struct stm32_dfsdm *dfsdm = dev_get_drvdata(dev);
+
+	return stm32_dfsdm_clk_prepare_enable(dfsdm);
+}
+
+static const struct dev_pm_ops stm32_dfsdm_core_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(stm32_dfsdm_core_suspend,
+				stm32_dfsdm_core_resume)
+	SET_RUNTIME_PM_OPS(stm32_dfsdm_core_runtime_suspend,
+			   stm32_dfsdm_core_runtime_resume,
+			   NULL)
+};
+
 static struct platform_driver stm32_dfsdm_driver = {
 	.probe = stm32_dfsdm_probe,
+	.remove = stm32_dfsdm_core_remove,
 	.driver = {
 		.name = "stm32-dfsdm",
 		.of_match_table = stm32_dfsdm_of_match,
+		.pm = &stm32_dfsdm_core_pm_ops,
 	},
 };