iio: adc: mt7622: add support for suspend/resume.

This patch supports auxadc suspend/resume flow.
Disable auxadc clk and power in suspend function.
Enable axuadc clk and power in resume function.
Signed-off-by: Zhiyong Tao <zhiyong.tao@mediatek.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/mt6577_auxadc.c

@@ -184,6 +184,37 @@ static const struct iio_info mt6577_auxadc_info = {
 	.read_raw = &mt6577_auxadc_read_raw,
 };
 
+static int __maybe_unused mt6577_auxadc_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct mt6577_auxadc_device *adc_dev = iio_priv(indio_dev);
+	int ret;
+
+	ret = clk_prepare_enable(adc_dev->adc_clk);
+	if (ret) {
+		pr_err("failed to enable auxadc clock\n");
+		return ret;
+	}
+
+	mt6577_auxadc_mod_reg(adc_dev->reg_base + MT6577_AUXADC_MISC,
+			      MT6577_AUXADC_PDN_EN, 0);
+	mdelay(MT6577_AUXADC_POWER_READY_MS);
+
+	return 0;
+}
+
+static int __maybe_unused mt6577_auxadc_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct mt6577_auxadc_device *adc_dev = iio_priv(indio_dev);
+
+	mt6577_auxadc_mod_reg(adc_dev->reg_base + MT6577_AUXADC_MISC,
+			      0, MT6577_AUXADC_PDN_EN);
+	clk_disable_unprepare(adc_dev->adc_clk);
+
+	return 0;
+}
+
 static int mt6577_auxadc_probe(struct platform_device *pdev)
 {
 	struct mt6577_auxadc_device *adc_dev;
@@ -269,6 +300,10 @@ static int mt6577_auxadc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static SIMPLE_DEV_PM_OPS(mt6577_auxadc_pm_ops,
+			 mt6577_auxadc_suspend,
+			 mt6577_auxadc_resume);
+
 static const struct of_device_id mt6577_auxadc_of_match[] = {
 	{ .compatible = "mediatek,mt2701-auxadc", },
 	{ .compatible = "mediatek,mt8173-auxadc", },
@@ -280,6 +315,7 @@ static struct platform_driver mt6577_auxadc_driver = {
 	.driver = {
 		.name   = "mt6577-auxadc",
 		.of_match_table = mt6577_auxadc_of_match,
+		.pm = &mt6577_auxadc_pm_ops,
 	},
 	.probe	= mt6577_auxadc_probe,
 	.remove	= mt6577_auxadc_remove,