[PATCH v4 3/6] iio: light: stk3310: Implement vdd and leda supplies

[Aren Moynihan <aren@peacevolution.org>]

The vdd and leda supplies must be powered on for the chip to function
and can be powered off during system suspend.

This was originally based on a patch by Ondrej Jirman[1], but has been
rewritten since.

1: https://codeberg.org/megi/linux/commit/a933aff8b7a0e6e3c9cf1d832dcba07022bbfa82

Signed-off-by: Aren Moynihan <aren@peacevolution.org>
---

Notes:
    Changes in v4:
     - fix variable declaration order in stk3310_resume to match the rest of
       the driver
    
    Changes in v3:
     - use bulk regulators instead of two individual ones
     - handle cleanup using devm callbacks instead of the remove function
    
    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 | 76 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 74 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/light/stk3310.c b/drivers/iio/light/stk3310.c
index 181b7acb3f96..f93689c61f44 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>
@@ -130,6 +132,7 @@ struct stk3310_data {
 	struct regmap_field *reg_int_ps;
 	struct regmap_field *reg_flag_psint;
 	struct regmap_field *reg_flag_nf;
+	struct regulator_bulk_data supplies[2];
 };
 
 static const struct iio_event_spec stk3310_events[] = {
@@ -621,6 +624,31 @@ static irqreturn_t stk3310_irq_event_handler(int irq, void *private)
 	return IRQ_HANDLED;
 }
 
+static int stk3310_regulators_enable(struct stk3310_data *data)
+{
+	int ret;
+
+	ret = regulator_bulk_enable(ARRAY_SIZE(data->supplies), data->supplies);
+	if (ret)
+		return ret;
+
+	/* we need a short delay to allow the chip time to power on */
+	fsleep(1000);
+
+	return 0;
+}
+
+static void stk3310_regulators_disable(void *private)
+{
+	int ret;
+	struct stk3310_data *data = private;
+	struct device *dev = &data->client->dev;
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(data->supplies), data->supplies);
+	if (ret)
+		dev_err(dev, "failed to disable regulators: %d\n", ret);
+}
+
 static int stk3310_probe(struct i2c_client *client)
 {
 	int ret;
@@ -642,6 +670,13 @@ static int stk3310_probe(struct i2c_client *client)
 
 	devm_mutex_init(&client->dev, &data->lock);
 
+	data->supplies[0].supply = "vdd";
+	data->supplies[1].supply = "leda";
+	ret = devm_regulator_bulk_get(&client->dev, ARRAY_SIZE(data->supplies),
+				      data->supplies);
+	if (ret)
+		return dev_err_probe(&client->dev, ret, "get regulators failed\n");
+
 	ret = stk3310_regmap_init(data);
 	if (ret < 0)
 		return ret;
@@ -652,6 +687,16 @@ static int stk3310_probe(struct i2c_client *client)
 	indio_dev->channels = stk3310_channels;
 	indio_dev->num_channels = ARRAY_SIZE(stk3310_channels);
 
+	ret = stk3310_regulators_enable(data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "regulator enable failed\n");
+
+	ret = devm_add_action_or_reset(&client->dev, stk3310_regulators_disable, data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret,
+				     "failed to register regulator cleanup\n");
+
 	ret = stk3310_init(indio_dev);
 	if (ret < 0)
 		return ret;
@@ -682,18 +727,45 @@ static int stk3310_probe(struct i2c_client *client)
 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);
+
+	ret = regulator_bulk_disable(ARRAY_SIZE(data->supplies), data->supplies);
+	if (ret) {
+		dev_err(dev, "failed to disable regulators: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
 }
 
 static int stk3310_resume(struct device *dev)
 {
-	u8 state = 0;
+	int ret;
 	struct stk3310_data *data;
+	u8 state = 0;
 
 	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	ret = stk3310_regulators_enable(data);
+	if (ret) {
+		dev_err(dev, "Failed to re-enable regulators: %d", ret);
+		return ret;
+	}
+
+	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)
-- 
2.47.0