[PATCH v2 2/6] iio: light: stk3310: Implement vdd supply and power it off during suspend

[Aren Moynihan <aren@peacevolution.org>]

From: Ondrej Jirman <megi@xff.cz>

VDD power input can be used to completely power off the chip during
system suspend. Do so if available.

Signed-off-by: Ondrej Jirman <megi@xff.cz>
Signed-off-by: Aren Moynihan <aren@peacevolution.org>
---

Notes:
    Changes in v2:
     - always enable / disable regulators and rely on a dummy regulator if
       one isn't specified
     - replace usleep_range with fsleep
     - reorder includes so iio headers are last
     - add missing error handling to resume

 drivers/iio/light/stk3310.c | 49 ++++++++++++++++++++++++++++++++++---
 1 file changed, 46 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/light/stk3310.c b/drivers/iio/light/stk3310.c
index 7b71ad71d78d..a0547eeca3e3 100644
--- a/drivers/iio/light/stk3310.c
+++ b/drivers/iio/light/stk3310.c
@@ -13,6 +13,8 @@
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+
 #include <linux/iio/events.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -117,6 +119,7 @@ struct stk3310_data {
 	struct regmap_field *reg_int_ps;
 	struct regmap_field *reg_flag_psint;
 	struct regmap_field *reg_flag_nf;
+	struct regulator *vdd_reg;
 };
 
 static const struct iio_event_spec stk3310_events[] = {
@@ -607,6 +610,10 @@ static int stk3310_probe(struct i2c_client *client)
 
 	mutex_init(&data->lock);
 
+	data->vdd_reg = devm_regulator_get(&client->dev, "vdd");
+	if (IS_ERR(data->vdd_reg))
+		return dev_err_probe(&client->dev, ret, "get regulator vdd failed\n");
+
 	ret = stk3310_regmap_init(data);
 	if (ret < 0)
 		return ret;
@@ -617,9 +624,17 @@ static int stk3310_probe(struct i2c_client *client)
 	indio_dev->channels = stk3310_channels;
 	indio_dev->num_channels = ARRAY_SIZE(stk3310_channels);
 
+	ret = regulator_enable(data->vdd_reg);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "regulator vdd enable failed\n");
+
+	/* we need a short delay to allow the chip time to power on */
+	fsleep(1000);
+
 	ret = stk3310_init(indio_dev);
 	if (ret < 0)
-		return ret;
+		goto err_vdd_disable;
 
 	if (client->irq > 0) {
 		ret = devm_request_threaded_irq(&client->dev, client->irq,
@@ -645,32 +660,60 @@ static int stk3310_probe(struct i2c_client *client)
 
 err_standby:
 	stk3310_set_state(data, STK3310_STATE_STANDBY);
+err_vdd_disable:
+	regulator_disable(data->vdd_reg);
 	return ret;
 }
 
 static void stk3310_remove(struct i2c_client *client)
 {
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct stk3310_data *data = iio_priv(indio_dev);
 
 	iio_device_unregister(indio_dev);
 	stk3310_set_state(iio_priv(indio_dev), STK3310_STATE_STANDBY);
+	regulator_disable(data->vdd_reg);
 }
 
 static int stk3310_suspend(struct device *dev)
 {
 	struct stk3310_data *data;
+	int ret;
 
 	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
 
-	return stk3310_set_state(data, STK3310_STATE_STANDBY);
+	ret = stk3310_set_state(data, STK3310_STATE_STANDBY);
+	if (ret)
+		return ret;
+
+	regcache_mark_dirty(data->regmap);
+	regulator_disable(data->vdd_reg);
+
+	return 0;
 }
 
 static int stk3310_resume(struct device *dev)
 {
-	u8 state = 0;
 	struct stk3310_data *data;
+	u8 state = 0;
+	int ret;
 
 	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	ret = regulator_enable(data->vdd_reg);
+	if (ret) {
+		dev_err(dev, "Failed to re-enable regulator vdd\n");
+		return ret;
+	}
+
+	fsleep(1000);
+
+	ret = regcache_sync(data->regmap);
+	if (ret) {
+		dev_err(dev, "Failed to restore registers: %d\n", ret);
+		return ret;
+	}
+
 	if (data->ps_enabled)
 		state |= STK3310_STATE_EN_PS;
 	if (data->als_enabled)
-- 
2.44.0