[PATCH v4] regulator: core: Limit propagation of parent voltage count and list

[Matthias Kaehlcke <mka@chromium.org>]

Commit 26988efe11b1 ("regulator: core: Allow to get voltage count and
list from parent") introduces the propagation of the parent voltage
count and list for regulators that don't provide this information
themselves. The goal is to support simple switch regulators, however as
a side effect normal continuous regulators can leak details of their
supplies and provide consumers with inconsistent information.

Limit the propagation of the voltage count and list to switch
regulators.

Fixes: 26988efe11b1 ("regulator: core: Allow to get voltage count and
  list from parent")
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
Changes in v4:
- Removed redundant check of .get_voltage_sel (implicitly done by .list_voltage check)
- Added 'Fixes' tag to commit message

Changes in v3:
- Removed unused variable ops from regulator_count_voltages()
- Updated commit message to use correct format for referencing commits

Changes in v2:
- Added flag 'is_switch' that indicates if regulator is a switch
- Reworked conditions checking for switch to evaluate the new flag

 drivers/regulator/core.c         | 9 +++++++--
 include/linux/regulator/driver.h | 2 ++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 53d4fc70dbd0..a99a975fb89f 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2486,7 +2486,7 @@ static int _regulator_list_voltage(struct regulator *regulator,
 		ret = ops->list_voltage(rdev, selector);
 		if (lock)
 			mutex_unlock(&rdev->mutex);
-	} else if (rdev->supply) {
+	} else if (rdev->is_switch && rdev->supply) {
 		ret = _regulator_list_voltage(rdev->supply, selector, lock);
 	} else {
 		return -EINVAL;
@@ -2544,7 +2544,7 @@ int regulator_count_voltages(struct regulator *regulator)
 	if (rdev->desc->n_voltages)
 		return rdev->desc->n_voltages;
 
-	if (!rdev->supply)
+	if (!rdev->is_switch || !rdev->supply)
 		return -EINVAL;
 
 	return regulator_count_voltages(rdev->supply);
@@ -4099,6 +4099,11 @@ regulator_register(const struct regulator_desc *regulator_desc,
 		mutex_unlock(&regulator_list_mutex);
 	}
 
+	if (!rdev->desc->ops->get_voltage &&
+	    !rdev->desc->ops->list_voltage &&
+	    !rdev->desc->fixed_uV)
+		rdev->is_switch = true;
+
 	ret = device_register(&rdev->dev);
 	if (ret != 0) {
 		put_device(&rdev->dev);
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index dac8e7b16bc6..4cb1c9be6073 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -429,6 +429,8 @@ struct regulator_dev {
 	struct regulator_enable_gpio *ena_pin;
 	unsigned int ena_gpio_state:1;
 
+	unsigned int is_switch:1;
+
 	/* time when this regulator was disabled last time */
 	unsigned long last_off_jiffy;
 };
-- 
2.12.2.564.g063fe858b8-goog