linux-kernel - [PATCH AUTOSEL 4.19 161/209] mfd: ti_am335x_tscadc: Keep ADC interface on if child is wakeup capable

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Date:   Tue, 12 Nov 2019 20:49:37 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Vignesh R <vigneshr@...com>, Lee Jones <lee.jones@...aro.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.19 161/209] mfd: ti_am335x_tscadc: Keep ADC interface on if child is wakeup capable

From: Vignesh R <vigneshr@...com>

[ Upstream commit c974ac771479327b5424f60d58845e31daddadea ]

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@...com>
Signed-off-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/mfd/ti_am335x_tscadc.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
index fe8d335a4d74d..4660ad90ef556 100644
--- a/drivers/mfd/ti_am335x_tscadc.c
+++ b/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;
-- 
2.20.1