mfd: ti_am335x_tscadc: Keep ADC interface on if child is wakeup capable

[ Upstream commit c974ac77 ]

If a child device like touchscreen is wakeup capable, then keep ADC
interface on, so that a touching resistive screen will generate wakeup
event to the system.
Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/mfd/ti_am335x_tscadc.c

@@ -295,11 +295,24 @@ static int ti_tscadc_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static int __maybe_unused ti_tscadc_can_wakeup(struct device *dev, void *data)
+{
+	return device_may_wakeup(dev);
+}
+
 static int __maybe_unused tscadc_suspend(struct device *dev)
 {
 	struct ti_tscadc_dev	*tscadc = dev_get_drvdata(dev);
 
 	regmap_write(tscadc->regmap, REG_SE, 0x00);
+	if (device_for_each_child(dev, NULL, ti_tscadc_can_wakeup)) {
+		u32 ctrl;
+
+		regmap_read(tscadc->regmap, REG_CTRL, &ctrl);
+		ctrl &= ~(CNTRLREG_POWERDOWN);
+		ctrl |= CNTRLREG_TSCSSENB;
+		regmap_write(tscadc->regmap, REG_CTRL, ctrl);
+	}
 	pm_runtime_put_sync(dev);
 
 	return 0;